Jun-25-96
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TTSD - U.S. EPA
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WAQUOITBAY
WATERSHED
Ecological Risk Assessment
Planning and Problem
Formulation
... .-V^.^<»>^>--^>>"-.
RISK ASSESSMENT FORUM
U. S. ENVIRONMENTAL PROTECTION AGENCY
DRAFT, June 13,1996
RAF 021
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ACKNOWLEDGMENTS
This risk assessment was prepared by a diverse team representing organizations and agencies ,
interested in management and protection of the biota of the Waquoit Bay watershed. The risk
assessment was sponsored by the U.S. Environmental Protection Agency's Office of Water and
Office of Research and Development under a Risk Assessment Forum Technical Panel. Esther.
Peters of Tetra Tech, Inc. provided technical assistance to the team. Ivan Valiela and William van
der Schalie critically reviewed the draft document. The conclusions and recommendations
presented herein are those of the Waquoit Bay Watershed Ecological Risk Assessment Team.
TECHNICAL PANEL CHAIR:
Suzanne Marcy, U.S. EPA, Office of Research and Development, Washington, D.C.
t "
TEAM CO-CHAIRS:
Maggie Geist, Waquoit Bay National Estuarine Research Reserve, Waquoit, Massachusetts
Patti Tyler, U.S. Environmental Protection Agency Region I, Lexington, Massachusetts
TEAM MEMBERS:
David Dow, National Marine Fisheries Service, Northeast Fisheries Science Center,
Woods Hole, Massachusetts
Jeroen Gemtsen, Terra Tech, Inc., Owings Mills, Maryland . .
Chuck Spooner, U.S. Environmental Protection Agency, Office of Water, Washington,
D.C.
Cpnchi Rodriguez, U.S. Environmental Protection Agency, Office of Prevention,
Pesticides and Toxic Substances, Washington, D.C.
Vicki Atwell, U.S. Environmental Protection Agency, Office of Research and
Development, Washington, D.C.
DRAFTJune 13, 1996
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Ji Waquoit Bay Watershed Ecological Risk Assessment
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TABLE OF CONTENTS
Acknowledgments ; i
Table of Contents , . . . . . in
List of Tables . '. , . : . . .:................. iv
List of Figures . . iv
Executive Summary . . . . v
Introduction .'. , , . . 1
1.0 Planning the Risk Assessment ..... 3
1.1 Establishing the Management Goal ...... .' . .'.. . .'.. .'..!. 3
1.1.1 The Management Goal. . . .' 3
1.1.2 Interpreting the Management Goal for Risk Assessment ........... 3
1.1.3 Process for Selecting the Management Goal 4
1.2 Management Decisions .5
1.3 Purpose, Scope, and Complexity of the Risk Assessment . . . : . 6
2.0 Waquoit Bay Problem Formulation ....... i ..................... . . . . . . 9
2.1 Assessment of Available Information . ' . ''. 9
2.1.1 Characterization of the Ecosystem at Risk . . . . .'/... ... 9
2.1.2 Ecological Effects . 11
2.1.3 Sources and Stressors ...... . . .....:...... 12
2.2 Assessment Endpoint Selection . ... ...... 14
'2.2.1 The Assessment Endpoints . . 14
2.2.2 Endpoint Description and Rationale : . . . 15
2.2.3 Overlap of Assessment Endpoints and Their Application .
to the Risk Assessment . ...."........ 19
2.3 Conceptual Model Development . ; . . 19
2.3.1 Watershed Conceptual Model , 19
2.3.2 Risk Hypothesis Development 34
2.4 Analysis Plan .....: .. 39
2.4.1 Comparative Risk Analysis 39
2.4.2 Development of a Regional Model of Eelgrass Response
to Nutrient Loading 43
2.4.3 Future Nitrogen Loading to Waquoit Bay 49
2.4,3 Potential Future Analysis for Other Stressors 50
3. Literature Cited ......................... ...._, 53
Appendix A - List of Participants in the Waquoit Bay Watershed Case Study ............ 62
Appendix B - Newspaper Advertisement and Article on Waquoit Bay Watershed Case Study ... 63
Appendix C - Results of the Waquoit Bay Public Meeting 64
Table C-i: Environmental values/concerns that should be protected in the Waquoit Bay
Watershed -
Table C-2:,Types of Stressors affecting the Waquoit Bay Watershed
Table C-3: Waquoit Bay Watershed Stressors and ecological effects
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Appendix D - Risk Management Team Meeting Attendees .70
Appendix E - Assessment of Available Information . . . : 72
* ** (
Appendix F - Land Use in the Waquoit Bay Watershed -..,.,"... Ill
Tables
1. The Waquoit Bay watershed management goal, interpreted as 10 management objectives
that are implied by and needed to achieve the goal 4
\ ,
2. Summary statement of goals and objectives of federal, state, and local organizations with
management jurisdiction in Waquoit Bay 5
3. Nitrogen loading to .water table/chlorophyll concentrations, and mean biomass of
macrophytes in three selected subestuaries of Waquoit Bay 14
4. Relationship of assessment endpoints to management objectives ................. 15
5. Hypothesized effects matrix; each cell represents relative effect of a stressor
or endpoint 40
6. Stressor ranks under three scenarios 41
7. Relative duration of stressors 41
8. Interaction among stressors ;....... 41
, Figures
1. Waquoit Bay watershed and subwatersheds ..-..' 10
2» Waquoit Bay watershed conceptual model . .' 20
3. Eelgrass conceptual submodel . . . .24
4. Finfish community conceptual submodel 26
5. Waquoit Bay stream conceptual model 28
6. Waquoit Bay pond conceptual model '. . : 30
7. Waquoit Bay estuary conceptual model , 32
8. Martha's Vineyard, Nantucket, and south coast of Cape Cod, showing eelgrass beds in
1994 (heavy lines). Eelgrass beds shown only from Woods Hole to Pleasant Bay and on
the north coasts of Martha's Vineyard and Nantucket islands , ... 46
IV
Waquoit Bay Watershed Ecological Risk Assessment
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EXECUTIVE SUMMARY
The Waquoit Bay Watershed ;
Waquoit Bay is a small estuary on the south coast of Cape Cod, Massachusetts, prized by residents
and visitors for its aesthetic beauty and recreational opportunities. The watershed covers more
than 53 square kilometers (about 21 square miles) of freshwater streams and ponds, salt ponds and
marshes, pine and .oak forest, barrier beaches, and open estuarine waters. It provides a home,
spawning ground, and nursery for plant and animal life including piping plovers, least terns
(endangered birds), the sandplain gerardia (an endangered plant), and alewife, winter flounder,
blue crab, scallops and clams, and anadromous and catadromous fish. -
The history of Waquoit Bay illustrates this trend and the struggle between traditional economic
growth and conservation of natural resources. Initially valued for hunting, farming, and fishing,
Waquoit Bay now primarily provides aesthetic and recreational opportunities (WBNERR, 1989),
demands that have generated residential development, and business for local marine-dependent
industries.
The environmental problems facing Waquoit Bay include eutrophicaition, habitat loss, and resource
depletion (WBNERR, 1989). Eelgrass that provides life to many animals in the bay is being '
replaced by thick mats of macroalgae, resulting hi fish kills and the loss of bay scallops. The
underlying aquifer, which provides local communities their sole source of drinking water, is
contaminated by plumes from a Superfund site. Land development is changing the landscape and
contributing nutrients and contaminants to the bay. Several research projects and management
activities are under way to examine the problems hi the watershed and to provide protection for
threatened and endangered aquatic and. terrestrial species and habitats, to reduce or eliminate
pollution, and to restore damaged spawning and nursery sites hi the watershed.
The Waquoit Bay watershed was selected as one of the EPA-sponsored ecological risk assessment
case studies because of interest by local, state, and federal organizations hi the watershed, the type of
watershed (estuarine), the diversity of stressors (e.g., nutrients, sediments, obstructions, ground water
contamination), a substantial existing database, and willingness by the' Waquoit Bay National
Estuarine Research Reserve (WBNERR) and EPA Region I to lead the risk assessment team.
Management Goals
The team charged with designing a risk assessment for the Waquoit was comprised of an
interdisciplinary and interagency team of scientists and managers who began work in 1993. The
management goal was developed through a multistep planning process initiated and completed by
the Team: a public meeting 'to initiate the process, evaluation of goals by interested organizations in
the watershed, and a meeting of members of these organizations to review and approve the
management goal and Team-derived objectives. The overarching goal developed for the Waquoit
Bay watershed risk assessment is:
Reestablish and maintain water quality and habitat conditions in Waquoit Bay and associated
wetlands, freshwater rivers, and ponds to (1) support diverse, self-sustaining commercial,
recreational, and native fish and shellfish populations and (2) reverse ongoing degradation of
ecological resources in the watershed. ' .
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The goal was interpreted as 10 management objectives believed to be required to achieve the goal:
» Reduce or eliminate hypoxic or anoxic events , '
> Prevent toxic levels of contamination in water, sediments, and biota
» Restore and maintain self-sustaining native fish populations and their habitat
> Reestablish viable eelgrass beds and associated aquatic communities in the bay -
> Reestablish a self-sustaining'scallop population in the bay that can support a viable '
sport fishery, .
» Protect shellfish beds from bacterial contamination that results in closures
> Reduce or eliminate nuisance macroalgal growth
* Prevent eutrophication of rivers and ponds
> Maintain diversity of native biotic communities
» Maintain diversity of water-dependent wildlife .
These objectives were intended to state explicitly what kinds of management results were implied in
the general goal statement.
Assessment Endpoints .
Eight assessment endpoints were selected to represent estuarine and freshwater components, of the
ecosystem, and ecological and human health concerns: . .
Estuarine eelgrass habitat abundance and distribution
> Resident and juvenile nursery estuarine finfish species diversity and abundance
> Clam and other benthic invertebrate diversity, abundance, and distribution
> Migratory (sea run) brook trout and alewife herring reproduction
> Freshwater stream benthic invertebrate diversity and abundance
' ' ,
» ' Freshwater pond trophic status . . .
> Water-dependent wildlife species feeding and nesting habitat
*. Bacterial and contaminant content of fish and shellfish
The assessment endpoints are measurable attributes of valued resources identified in the
management goals, and the first six represent ecologically important components of the ecosystems.
vi Waquoit Bay Watershed Ecological Risk Assessment
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The include both an entity (e.g., eelgrass) and a measurable attribute (e.g. distribution), and they
provide direction for the assessment and are the basis for the development of questions, predictions,
models, and analyses. .
Conceptual Model
The conceptual models developed for the Waquoit Bay watershed represent a series of risk
hypotheses about the relationships between particular stressors arid ecological effects expected to be
observed in each assessment endpoint (Figure 2). The general watershed conceptual model is a
broad representation of relationships among human activities in the watershed (sources), the stressors
believed to occur as a result of those sources, and ecological effects likely to occur in each of the
assessment endpoints.
Eelgrass is highly susceptible to water quality conditions and requires clear waters with ample light
penetration for photosynthesis. Shading by algae and sediments directly impacts eelgrass growth.
Excessive growth of macroalgal mats has displaced eelgrass hi Waquoit Bay.
Finfish are susceptible to hyppxic and anoxic conditions and toxic contaminants.- The loss of :
eelgrass habitat encompasses a decrease hi coverage, a decrease in density of stems, the
displacement of eelgrass by macroalgae, or the conversion of eelgrass meadow to open .bottom with
sand or mud sediments. Macroalgal mats are less suitable than eelgrass as a refuge for finfish, and
the bottom of the macroalgal mat may be hypoxic. ..'.' . ;
The benthic community can be adversely affected by .loss of eelgrass, toxic and hypoxic conditions
arid macroalgal mats. Shellfish and other benthos are also sensitive to the degree of sedimentation
in breeding areas, the presence of critical habitats such as eelgrass beds and wetlands, and the.
extent of recreational and commercial harvesting mortality, including catch and by-catch. The
presence of eelgrass beds and sufficient water quality are thought to be the critical elements for
- supporting the appropriate habitat to maintain and promote a diverse and abundant estuarine benthic
faunal community. .--'..'
Spawning trout are susceptible to water quality changes. They depend on swiftly flowing, cold
waters that are high in dissolved oxygen. Alewife herring, which travel to John's Pond to spawn,
rely on sufficient water depth to traverse the bogs near the pond. Drops in the water table or
reduced flow can prevent access to spawning areas.
^ .
Each of the pathways from source to endpoints was created based on assumptions, or risk
hypotheses, about how stressors are affecting or are expected to affect targeted assessment endpoints.
They .were derived from available.information on the watershed from ecological theory on how
systems function, and from relationships established in other watersheds that are expected to be
consistent. The risk hypotheses developed for each assessment endpoint provide the foundation for
evaluating the cumulative and combined risk of more than one stressor.
Each of the stressors identified in the watershed has more than one source contributing to stress in
the watershed. As noted previously, nutrients in the form of nitrogen and phosphorus in groundwater
are chemical stressors implicated as a major cause of nuisance macro algal blooms and eelgrass
decline in the bay and increasing phytoplankton blooms in ponds. Chemicals that might be toxic to
aquatic..organisms are coming from the MMR contaminant plumes, storm drainage ditches, and
nonpoint sources such as road runoff,Emigration of pesticides, septic system leachate, and
DRAFTJune 13, 1996
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atmospheric deposition. Suspended and resuspended organic matter is a physical stressor that
increases turbidity and decreases light penetration to eelgrass beds. Physical alteration of estuarine
habitat includes increased sediment disturbance, bottom disruption, and shading from dock
construction; mechanical disruption from clam, digging, boat propellers, and moorings, and habitat
fragmentation that results from these activities. Hydrologic modification is another physical stressor
that results in altered stream flow patterns and reductions in the flow volume, velocity, and path of
rivers and results in loss of spawning habitat for anadromous fishes. Fishes are being harvested from
the estuary and rivers and ponds, as well as from offshore, affecting population abundances and the
composition of aquatic communities. Another potential biological stressor in the estuary is eelgrass .
wasting disease caused by the slime mold (Labyrinthuld).
Analysis Plan .
A large number of assessment endpoints were identified in this risk assessment. A comparative risk
analysis was conducted by the risk assessment team to help define which stressors, assessment
endpoints, and relationships should be examined further. For the preliminary analysis, stressors
were ranked in terms of potential risk to all resources in the watershed, using a "fuzzy set" decision
analysis method that is based on best professional judgment. The analysis ranks the stressors in
order of greatest overall contribution of risk to the endpoints, based on an ordinal effect of a stressor
on that endpoint, ranging from no effect to severe effect. The results of the comparative analysis -
ranked nutrients first, followed by physical alteration and toxic chemicals, then harvest and flow
alteration, and finally suspended sediments and eelgrass disease.
Based on the comparative risk analysis, and prevailing scientific opinion prior to the analysis, excess
nutrient loading is the principal stressor that prevents most of the management objectives from being
met. Thus, further analysis to be conducted for the ecological risk assessment of the Waquoit Bay
watershed will identify and address critical gaps in the relationship between nutrient loading and
assessment endpoints. The first part of the analysis will develop a predictive model of the response
of the extent and cover of eelgrass (ecological effect) to nutrient loading (exposure) in estuaries of
Cape Cod. The second part of the analysis will predict future nutrient loading to Waquoit Bay under
various scenarios of development..
The approach will be to develop one or more regression models of eelgrass cover in similar estuaries
found on Cape Cod. Eelgrass cover in each estuary, digitized from a series of aerial images, will be
the response variable. The principal predictive variable will be nitrogen loading, estimated for near
and more distant sources in each estuary using extant N loading models. An alternative model will
use watershed land use directly as a predictive variable. The objective is to develop predictive
relationships between estimated nitrogen loadings (from all sources) and eelgrass cover in Cape Cod
estuaries, to be applied to predicting the response of Waquoit Bay to future changes in N loading.
Achieving low nitrogen loading to Waquoit Bay will require nitrogen source control, as well as a
sufficient lag time to allow nitrogen currently in the ground water to be flushed out. The travel times
of ground water vary across the watershed, thus, nitrogen loading to the estuary is not a function of
land use at any one point in time. A second analysis will be conducted to examine the time lag
between contamination of ground water at the point of recharge and discharge to the estuary.
Nitrogen loading rates provided by the model will then be plotted against measures of ecological
effects. The two sets of models and their estimated uncertainties can then be used to predict the
effects of different nutrient management scenarios for Waquoit Bay.
viii Waquoit Bay Watershed Ecological Risk Assessment
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INTRODUCTION
Waquoit Bay is a small estuary on the south coast of Cape Cod, Massachusetts, prized by residents
and visitors for its aesthetic beauty and recreational opportunities. The watershed covers more
than 53 square kilometers (about 21 square miles) of freshwater streams and ponds, salt ponds and
marshes, pine and oak forest, barrier beaches, and open estuarine waters. It provides a home,
spawning ground, and nursery for a diversity of plant and animal life including piping plovers,
least terns ^endangered birds), the sandplain gerardia.(an endangered plant), and alewife, whiter
flounder, blue crab, scallops and clams, and anadromous and catadromous fish. But the bay is
changing. Eelgrass that provides life to many animals in the bay is being replaced by thick mats of
macroalgae. This has resulted in fish kills and the loss of bay scallops. The aquifer underlying the
watershed, which provides the communities of Falmouth, Mashpee, and Sandwich their sole source
of drinking water, is contaminated by plumes from a Superfund site. Land development is
changing the landscape and contributing nutrients and contaminants to the bay. Local communities
are concerned for their health and the value the bay adds to then1, lives. .
Worldwide, other estuaries are experiencing similar water quality problems as a result of increasing
numbers of people moving to coastal areas (Submerged Aquatic Vegetation Workgroup, 1995).
The history of Waquoit Bay in Falmouth and Mashpee illustrates this trend and the struggle
between traditional economic growth and conservation of natural resources. Initially valued for
hunting, farming, and fishing, Waquoit Bay now primarily provides aesthetic and recreational
opportunities (WBNERR, 1989), demands that have generated residential development and business
for local marine-dependent industries. Across Cape Cod more than 65,000 permits for single-
family homes were authorized between 1970 and 1989, a major portion of which were in Falmputh
and Mashpee (Cullitonetal., 1992).
The environmental problems Waquoit Bay faces include eutrophication, habitat loss, and resource
depletion (WBNERR, 1989). These changes led to the designation of Waquoit Bay as an Area of
Critical Environmental Concern (ACEC) in 1979 by the Commonwealth of Massachusetts. In
1988, the federal government and State of Massachusetts formally established the Waquoit Bay
National Estuarine Research Reserve (WBNERR). The estuary is a study site under the Waquoit
Bay Land Margin Ecosystems Research (LMER) project funded by the National Science
Foundation (NSF), the U.S. Environmental Protection Agency (EPA), and the National Oceanic
and Atmospheric Administration (NOAA). This is a multidisciplinary project studying the effects
of changing land use patterns on ecosystem function. LMER scientists, water resource scientists
from the Cape Cod Commission for regional planning, and scientists from the Buzzard's Bay
National Estuary Program are evaluating nutrient loading calculations and management options for
Waquoit Bay. In April 1995, a new U.S. Fish and Wildlife Refuge was established that will provide
a contiguous arc of undeveloped land on the bay. In place also are management plans for federally
endangered and otherwise protected species such as piping plovers, least terns, and roseate terns.
In May of 1994, Waquoit Bay was declared a Federal No-Discharge Zone., offering some
protection against dumping of boat wastes. Increased recreational boating and a proliferation of >
docks led to new regulations on dock construction'in the ACEC management plan. Along with
Waquoit Bay, the trout spawning reach of the Quashnet River has been designated an ACEC and
the,river classified as Class B, to be used for protection and propagation offish, other aquatic life
and wildlife and for primary and secondary-contact recreation (Baevsky, 1991).
EPA Region 1 formally nominated the Waquoit Bay watershed in 1993 for inclusion hi an EPA-
sponsored project to develop watershed-level ecological risk assessment case studies. Waquoit was
DRAFT^-June 13, 1996
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selected as one of five watersheds because of interest by local, state, and federal organizations in
the watershed, the type of watershed (estuarine), the diversity of stressors (e.g., nutrients,
sediments, obstructions, ground water contamination), willingness by the WBNERR and EPA
Region I to lead the risk assessment team, and a substantial existing database. Although significant
research has been completed in the watershed to date, the value added by c nducting a risk
assessment in the Waquoit Bay watershed is based on (1) a focus on multip;. stressors and relative
risk, (2) identification of significant data gaps and design of a research agenda that is more
balanced and broad-based, and (3) an interpretation of risk that is useful for pending management
decisions.
This document describes the work done by an interdisciplinary and inter agency team of scientists
and managers (see Appendix A) to develop the Waquoit Bay watershed ecological risk assessment.
It is organized into two sections. The first, on the management goal for the watershed, presents the
goal and the process used to establish it. The second section is the problem formulation for the risk
assessment. The analysis and risk characterization phases of the risk assessment are under
development.
Waquoit Bay Watershed Ecological Risk Assessment
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1.0 PLANNING THE RISK ASSESSMENT
The Waquoit Bay watershed ecological risk assessment was based on a proposal by managers "in
WBNERR and EPA Region 1 who were concerned about the changing quality of the Bay. Based
on this interest, a risk assessment team was assembled (Appendix A) and planning for the risk
assessment began in 1993. ,
The objectives of the planning were to establish clear and agreed-upon goals for watershed
resources, to determine the purpose for the risk assessment within the context of those goals, and to
agree on the scope and .complexity of the risk assessment (USEPA, 1996). One of the principal
challenges for meeting planning objectives for this risk assessment was to develop a management
goal for watershed resources that diverse members of the community could support. To meet the
requirements of planning, the risk assessment team (the Team) worked with watershed risk
managers (the Managers) to develop and implement a process for ascertaining the interests and
goals of the public; local, state, and federal organizations; and other resource managers in the
watershed. Below is a description of the goal and an explanation of how it was derived and
interpreted. The scope, complexity, and focus of the assessment are. also delineated. ,
' l
1.1 Establishing the Management Goal
The management goal for Waquoit Bay was generated through discussions with risk managers and
risk assessors in the watershed, participation on the Team by local risk managers, and dialogues
with interested parties concerned about watershed resources. .
1.1.1 The Management Goal
Reestablish and maintain water quality and habitat conditions in Waquoit Bay and associated
wetlands, freshwater rivers, and ponds to (1) support diverse, self-sustaining commercial,
recreational, and native fish and shellfish populations and (2) reverse ongoing degradation of
ecological resources in the watershed. '.
1.1.2 Interpreting the Management Goal for Risk Assessment
The management goal is a qualitative statement that captures the essential interests expressed by
different management organizations and the public in the Waquoit Bay watershed (see Section
1.1.3). In order for the management goal to support an ecological risk assessment, the goal was
evaluated by the Team and interpreted as 10 management objectives believe4 to be required to ,
achieve the goal (see Table 1). These objectives were intended to state explicitly what kinds of
management results were implied in the general goal statement. By performing this kind of
evaluation, the Team provided feedback to the managers on the ecological characteristics of the
goal, developed a systematic process for identifying assessment endpoints that could .be'directly
linked to the management goal, and provided a way to measure achievement of the" goal for risk
managers. ;
Table 1 is partitioned into three categories. The "Estuarine and Freshwater" category includes
three objectives that are common to both surface water types. Four objectives under the
"Estuarine" category and three objectives under the "Freshwater" category are unique to those
waters: The 10 objectives are stated as goals for specific aspects of exposure, stressors, and valued
DRAFTJune 13, 1996
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ecological resources. Assessment endpoints were selected and justified based on these objectives
(see Section 2.3). Although the goal was developed by the Managers, the specific management' '.
objectives were generated by the Team based on available information on watershed resources.
The objectives were then-provided to managers for their consideration and approval (see Section
1.1.3). ' .
Table 1. The Waquoit Bay watershed management goal, interpreted as 10 management objectives that
are implied by and needed to achieve the goal.
Affected Area
Estuarinc and
Freshwater
Estuarinc
Freshwater
Number
1
2
3-
4
5
6
7
8
9
10
Component Management Objective
Reduce or eliminate hypoxic or anoxic events
Prevent toxic levels of contamination in water, sediments, and biota
Restore arid maintain self-sustaining native fish populations and their habitat
Reestablish viable eelgrass beds and associated aquatic communities in the bay
Reestablish a self-sustaining scallop population in the bay that can support a viable
sport fishery '
Protect shellfish beds from bacterial contamination that results in closures
Reduce or eliminate nuisance macroalgal growth
Prevent eutrophication of rivers and ponds
Maintain diversity of native btotic communities
Maintain diversity of water-dependent wildlife
1.1.3 Process for Selecting the Management Goal
The management goal was developed through a multistep process initiated and completed by the
Team. Three principal approaches were used: a public meeting, evaluation of written goals by
organizations having jurisdiction over or interest in the ecological resources of the watershed, and a
meeting of members of these organizations to review and approve the management goal and Team-
derived objectives.
Public Meeting. EPA, in conjunction with WBNERR, held a public forum on September 21,
1993. The forum was advertised and reported in local newspapers (Appendix B) to receive input
on what was valuable to the public about the Waquoit Bay watershed and what the public believed.
were the principal stressors placing these values at risk. Each participant was asked to answer two
questions: (1) What do you value in the watershed? (2). What is placing those values at risk?
Participants provided a substantial list of values and an array of chemical, physical, and biological
stressors (Appendix C). This feedback provided a basis for Team generation of a working
management goal, which was used to guide the collection and evaluation of available information
during the initial stages of problem formulation.
Organizational Goals. The written goals established for Waquoit Bay by local, regional, and
national resource management organizations with jurisdiction in the watershed were collected by
the Team and summarized. Based on written documentation published by the organizations, or as
represented by statute, the Team generated short descriptors which are provided in Table 2. These
organizational goals were'used to refine the risk assessment management goal and develop the 10
management objectives.
Waquoif Bay Watershed Ecological Risk Assessment
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Risk Management Team Consensus. To finalize the management goal, members of concerned
organizations (see Appendix D) were invited to a meeting sponsored by WBNERR in Waquoit on
February 24, 1995. The working management goal, the summary of organizational goals, and the
interpretation of the goal as 10 management objectives was presented to meeting participants. The
management goal and objectives for the risk assessment were approved as modified by the
organization representatives at the-meeting. Participants hi this meeting are Considered the risk
management team for the risk assessment. They Will be principally responsible for implementing
management plans in Waquoit Bay.
Table 2. Summary statement of goals and objectives of federal, state, and local organizations with
management jurisdiction in Waquoit Bay.
: Organization .;- : ' ;-:,.:":
Association for the Preservation of Cape
Cod
Atlantic States Marine Fisheries
Commission
Cape ,C6d Commission
* Citizen Action Committee (formed of
representatives from other groups)
Citizens for the Protection of Waquoit , .
Bay
Massachusetts Coastal Zone Management
Massachusetts Department of
Environmental Protection . >
National Marine Fisheries Service
NOAA National Estuarine Research
Reserve System
U. S. Army Corps of Engineers
U. S. Environmental Protection Agency
U. S. Fish and Wildlife Service
Waquoit Bay National Estuarine
Research Reserve ,
Waquoit Bay Watershed Intel-municipal
Committee
,' ';'-. '-:'." ::': .V?':v;:;f/-::-:#«- ";. '- :-ExampIe-Goa1:-:'::;-:;f::v;'.'-;''"'''"-:''- :;. ;'.. ..' "'
"Assist [other organizations] ... to decrease nitrogen loading to Waquoit Bay"
Coordinates marine fisheries management in state waters
"Protect the region's resources .... protect and improve coastal water quality and
shellfish habitat"
Reverse ongoing degradation and protect water quality and habitats of Waquoit
Bay
"Preservation of the environment (physical, aesthetic and otherwise) and the
natural resources of the Waquoit Bay area"
"Protection of natural and cultural resources in the coastal zone"
Non-degradation of coastal waters (Waquoit Bay is class SA, or waters with DO
> 5 mg/L and where shellfish do not require depuration)
Implements Magnuson Act for marine fisheries management in federal waters,
and the Marine Mammal Protection Act (with USFWS)
"Establish and manage a national' network of protected areas .... Mobilize .
federal, state and community resources to mutually define and achieve coastal
protection and management goals and objectives"
Regulation and maintenance of navigational channels in rivers and harbors;
oversight over coastal armoring; issue permits for construction in waters and
. wetlands (Section 404) .
Implementation of national environmental laws, including the Clean Water Act
Implementation of the Endangered Species Act; management of National Wildlife
Refuges '
- "Protect in perpetuity for the purposes of research and education; .... Promote
stewardship and estuarine awareness through outreach activities..."
"Evaluate possible options to improve water quality in the watershed"
1.2 Management Decisions
The ongoing and easily observed degradation occurring in Waquoit Bay is causing managers in the
watershed to look for better ways to manage valued resources. Key issues requiring decisions
include nutrient control, reducing bacterial contamination in shellfish, and'containment of ground
DRAFT-June 13, 1996
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water contamination. To achieve the goals for the watershed, there might .also be other important
considerations. ' .'
Nutrient inputs to the watershed are recognized as a serious problem. Managers are considering the
feasibility of installing denitrification technology and alternative sewage treatment for homes and
businesses along the bay and hi the surrounding watershed. Treatment of sewage is a critical issue
that must be addressed on technical, financial, and ecological grounds. The risk assessment is to
address the impact of nitrogen in the watershed and predict the effectiveness of nitrogen reduction
. in meeting management goals. Bacterial contamination of shellfish beds is a related concern for
septic system management. .
Managers are evaluating alternative management options for protecting the watershed from ground
water contaminants now reaching the ponds and expected to reach the estuary within 10 years. A
proposed extraction and treatment plan might result in more significant ecological effects than will
occur if exposure to the contaminants is allowed. Alternative options must be considered:
'
Boating and clamming activities are increasing in the Bay and might require more stringent
controls. Location of boating traffic and clamming could be important to reestablishing important
infaunal and epifaunal benthic communities. Better enforcement of speed limits and fishing
activities might be necessary. . . .
Among the more critical considerations for many of these stressors is land development and use..
Recommendations concerning land use that are based on ecological risk are desired.
1.3 Purpose, Scope, and Complexity of the Risk Assessment
The purpose of this risk assessment was to determine what and how human activities are
contributing to ongoing degradation of valued ecological entities in the Waquoit Bay watershed.
Specifically, it was designed to evaluate the relative contributions of dominant stressors to support
management decisions about changing land use, installing new septic system treatment technology,
evaluating management options for cleanup of grouridwater contamination, identifying key research
needs, and providing the framework for predicting what effect possible management actions will
have on key ecological resources at risk. The risk assessment was not legally mandated.. The
WBNERR is particularly interested in the risk assessment as a vehicle for developing a research
agenda. The risk assessment will also serve as a source of information as several governmental
organizations begin management of contaminated ground water. . ,
The intended scope of the assessment was to address individual stressors' effects and the combined
risk of multiple stressors within the last 10 years in comparison with historical records spanning 50
years. Although significant data on the watershed have been collected, most are related to nutrient
inputs and "build-out" (i.e., residential and otiier land development), with additional data on
groundwater contamination. Relatively few data are available on the biological changes associated
with specific levels of these stressors or other stressors identified by the Team, although this is
beginning to change, hi part due to the development of problem formulation. While the problem
formulation is as broad as possible, the scope of the risk assessment was narrowed to reflect data
limitations. Where data are few, the Team identified key.-missing information and made
recommendations on types of data collection for future work to assess the combined impacts of
multiple stressors. .. ,
Waquoit Bay Watershed Ecological Risk Assessment
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During problem formulation, the intent of the Team was to be as complete and comprehensive as
possible about relationships between stressors and ecological values selected as assessment
endpoints within the 21-square-mile area representing the surface watershed. The conceptual'.
models developed include all identified sources "of stress, stressor types, effects, and a selection of
assessment endpoints that best represent the management goal for the fresh and estuarine waters of
the watershed. The terrestrial component is not represented hi the risk assessment aside from one
assessment endpoint on Water-dependent wildlife habitat and recognition that terrestrial impacts
influence what occurs within water. Although the ground water component underlies the
watershed, it is not confined within the 21-square-mile area and therefore represents a scale larger
than that of this risk assessment.
Once conceptual models were developed, it was the intent of the Team to select specific stressor-
assessment endpoint relationships to pursue based on both the importance of the' relationship to
perceived overall risk and the amount of data available to evaluate the relationship. In some cases
assumptions were made to allow analysis, understanding that these assumptions add to the
uncertainty of results. The, Team will attempt to evaluate the combined risk of multiple stressors.
Limitations in the risk assessment reflect significant limitations on available resources. All
members of the risk assessment team are professionals from federal, state, and local organizations,
who provided their expertise and time without grant or contract funds. Limited contract support
was used to provide some assistance to the team. Although efforts were made to foster more
academic participation, this was directly limited by the Team's, inability to provide funding. Key
researchers in the watershed were included as resource people. No new data were collected to
conduct this assessment, but best efforts were made to use available data effectively. .The success
of this risk assessment was based on effective leveraging of available resources. Limitations,
although significant- did not prevent the achievement of important results.
DRAFTJune 13, 1996
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Waquoit Bay Watershed Ecological Risk Assessment
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2.0 WAQUOIT BAY PROBLEM FORMULATION
To develop problem formulation, a formal process was used to generate preliminary hypotheses
about why ecological effects in Waquoit Bay have occurred and to predict changes in ecological
responses both to continuing stressor inputs and to identified management actions that might reduce
stressor inputs. .In the watershed, stressors of long duration were identified, as well as potential
risks from expected future human activities. To complete problem formulation, it was necessary to
evaluate historical records on the ecological characteristics of the bay and the dominant human
activities over comparable time periods, as well as to evaluate current status. This information
provided the basis for predicting ecological responses to management actions and future stressors.
The Waquoit Bay problem formulation is based on an assessment of available information that
provided the foundation for risk hypothesis development. A brief summary of key information is
provided below and supplemented by more detailed information in Appendix E. Based on the
management goal and available information, assessment endpoints were selected by the Team.
These assessment endpoints were used as the focus in the development of conceptual models and
, the analysis plan. The following sections describe the result of these steps in the problem
formulation process. -
2.1 Assessment of Available Information
The initial step hi problem formulation was to identify and assess available information on the
characteristics of the watershed, observed ecological effects, and possible stressors on the system.
This section provides a brief overview of information on the Waquoit Bay watershed. It highlights
the information most pertinent to understanding the risk assessment and is not intended to be
comprehensive. More comprehensive information is provided hi Appendix E.
2.1.1 Characterization of the Ecosystem at Risk
"i .
The Waquoit Bay watershed covers more than 53 square kilometers (about 21 square miles) and
spans parts of the towns of Falmouth, Mashpee, and Sandwich on the south coast of Cape Cod,
Massachusetts (Babione, 1990; Cambareri et al., 1992j 1993). It extends 8 kilometers (5 miles)
from the head of the bay to the regional ground water divide in the vicinity of Snake Pond (Figure
1). The watershed includes estuarine and freshwater systems encompassed in seven subwatersheds
(Childs River, Sage Lot Pond, Quashnet River, Eel Pond, Head of the Bay, Hamblin Pond, and
Jehu Pond) .and four large ponds (Ashumet, Johns, Snake, and Flat). , .
The Waquoit Bay watershed, like all of Cape Cod, is a geologically young landform composed of
glacial materials deposited on top of bedrock toward the end of the Wisconsinian Glacial Stage
about 12,000 years ago (LeBlanc et al., 1986; Oldale, 1992).. The watershed lies entirely within
the Mashpee pitted outwash plain. The term pitted refers to sites where blocks of glacial ice were
buried during glacial retreat. When the blocks melted, depressions formed and filled with water,
creating numerous kettle ponds (e.g., Ashumet and Johns ponds).
DRAFTJune 13, 1996
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Watershed
Map Area
Subwatersheds:
1-Eel Pond
2 - ChUds River
3 -Quashriet River
4-Head of the Bay
5 -HamblinPbnd
6-Jehu Pond
7 - Sage Lot Pond
A - Ashumet Pond
B - John's Pond
C - Snake Pond
D-Flat Pond
Figure 1. Waquoit Bay watershed and subwatersheds (Brawley and Sham, in prep.).
10
.Waquoit Bay Watershed Ecological Risk Assessment
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Waquoit Bay may have originated as a kettle porid whose southern margin was flooded by
subsequent sea level rise. The bay is a shallow estuary approximately 1.2, km (4,000 feet) wide, and
3.4 km (11,000 feet) long with ah average depth of 0.9 m (3 ft). Tidal exchange to Vineyard-
Sound occurs through two dredged channels and a breach caused by Hurricane Bob in 1991. The
action of winds, waves, and currents continually erodes and displaces the loose glacial sand and
gravel forming coastal sarid.dunes, sea cliffs, barrier beaches, and salt marshes.
The watershed's climate is maritime, with warmer winters and cooler summers than more inland
areas of New England, and annual precipitation between 107 and 112 cm (42 and 44 hi). Fifty
percent of fresh water entering the Waquoit Bay estuary is from precipitation-23 percent from
direct precipitation and 27 percent from groundwater recharge (Cambareri et al., 1992). Ground
water recharge is approximately 45 percent of the total precipitation. The remaining 50 percent of
fresh water entering Waquoit Bay conies from the Quashnet and Childs,Rivers. The porous, sandy.
glacial soils promote rapid percolation of rain, nutrients, and contaminants into the subsoil and
ground water. Little surface runoff occurs.
.Cold south-flowing Gulf of Maine waters and warm north-flowing Gulf Stream, waters mix off the
coast of Cape Cod to form a biological transition zone between the Virginian (temperate) and
Acadian (boreal) biogeographic provinces (Ayvaziam et al., 1992), producing more diverse biotic
communities and habitats than occur in either province. The combination of salt, estuarine, and
freshwater systems within the watershed augment this diversity. Critical resources in the Waquoit
Bay watershed include freshwater wetlands on the pond shores; anadromous fish runs in the rivers;
salt marshes, eelgrass beds, and barrier beaches in the estuary; and upland woodlands (VanLuven,
1991). The surface water ecosystems support a variety of food resources for aquatic, terrestrial,'
and avian wildlife and include commercially and recreationally important finfish and shellfish.
2.1.2 Ecological Effects
Water resources in the Waquoit Bay watershed are exhibiting signs of water quality degradation.
Waquoit Bay is becoming eutrophic, as evidenced by excess algal, growth that decreases light
penetration. Light-dependent eelgrass beds have almost disappeared from the bay. Documented
declines in numbers of winter flounder, .tauog, summer flounder, blue crabs, bay scallops, and
other eelgrass- dependent species parallel the loss of eelgrass. The bay scallop, an important
commercial and sport species, has virtually disappeared. When several consecutive cloudy days
occur during summer months, mass deaths of aquatic organisms occur, presumably from respiring
algae that deplete dissolved oxygen. Increasing incidents of shellfish bed closure from bacterial
contamination are also a source of concern in the estuary.
Freshwater components of the watershed also are changed. Stream flow alterations have resulted
in a loss of reproductive habitat for traditional herring runs and migratory fish spawning areas.
Malformations and tumors in fish living in the kettle ponds may be indicative of exposure to
contaminants. Freshwater ponds are showing increasing levels of algal growth, which is likely to
alter the aquatic community. Targeted changes of.concern include:
- . . >. '
> Blooms of phytoplankton and macroalgae.
» Loss of eelgrass habitat and associated species, hi particular, bay scallops.
Changes hi species composition and declining abundances of commercially
important finfish and shellfish.
DRAFTJune 13, 1996
11
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> Mass mortalities of fishes and. invertebrates in the upper bay and ponds.
> Reduced water flows in herring runs and trout streams. . "
2.1.3 Sources and Stressors .
Multiple sources of stress were identified in the watershed. For each of these sources, multiple
Stressors could also be identified. More than one source may produce the same complement of
stressor types, but the exposure pathway and specific characteristics of the Stressors may vary. The
following highlights key sources and key stressor types with minimal discussion of exposure
pathways and characteristics. Refer to Appendix E and the section on conceptual models (Section
2.3) for more information.
Sources. -The main sources of stress identified in the Waquoit Bay watershed include agriculture,
atmospheric deposition, residential development,- industrial uses, and marine activities. Changing
land and water use patterns along the coastal and upland areas in the Waquoit Bay watershed are
largely responsible "for increasing Stressors in the watershed (Appendix F). Some of these affect
local resources but occur outside the watershed, including armoring,of the coast, which shifts
sediment deposition along barrier beaches; offshore fishing, which depletes stocks of commercially .
valuable species; and wet and dry atmospheric deposition from motorized vehicles and industries.
Principal sources of stress in the watershed include the following:
> Cranberry cultivation which results in the use of fertilizers, the application of
pesticides and herbicides, and the construction of flow control structures that alter
surface water flow.
» Atmospheric deposition from local and regional automobiles, lawn mowers, and
motor boats; on a larger spatial scale, .nutrients (in the form of nitrogen oxides,
NOx's) from industrial emissions, and toxic chemicals, including mercury, that
originate outside the watershed.
" > Residential development, which contributes nutrients to the system through
fertilizer use on lawns, golf courses, and gardens, and on-site septic systems;
housing and road construction, which results in habitat loss, sedimentation, and
additional runoff of nutrients, contaminants, and sediments from construction sites,'
and an increase in impervious surfaces; and private and municipal well .
development, which alters ground water flow.
> Industrial discharges to groundwater from the Massachusetts Military Reservation
(MMR), a Superfund site on the upper western portion of Cape Cod that is
contaminating ground water (a sole source aquifer for drinking water) with
chlorinated solvents and fuel constituents; its sewage treatment facilities contribute
in phosphorus to ponds; and the MMR contributes increased runoff of nutrients,
sediments, and contaminants from impervious surfaces.
» Marine activities including construction and operation of marinas; and recreational
boating and dock and pier construction which disturbs sediments, alters habitats,
and contributes nutrients and contaminants; dredging and shoreline modification for
waterway maintenance, which disturbs sediments; shellfishing which disrupts
eelgrass habitat, resuspends sediments, and adds harvest pressure; and recreational
12 Waquoit Bay Watershed Ecological Risk Assessment
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fishing in the estuarine, river, and pond environments, which alsp adds harvest
pressure. .
Stressors. Seven principal stressors were identified-two chemical, three physical, and two
biological. Each stressor has more than one source contributing to stress in the watershed. Each
stressor was characterized on the basis of its type, its mode of action, and the general ecological
effects that might result from exposure to the stressor. In addition, information on the intensity,
frequency, duration, and spatial scale were,reviewed for each stressor where available. Principal
stressors include:
> Nutrients, which are .implicated as a major cause of nuisance macroalgal blooms
and eelgrass decline in the bay (Table 3) and increasing phytoplankton blooms in
ponds in part because of the porous, sandy soils in the watershed, which promote
rapid percolation of nutrients from land deposition, septic systems, and other inputs
into ground water. ; ,
» Chemicals that may be toxic to organisms in the bay, streams, and ponds, primarily
mobilized chlorinated solvents and fuel constituents from MMR contaminant
plumes, open storm drainage ditches, and nonpoint sources such as .road runoff,
migration of pesticides, on-site-septic disposal system leachate and atmospheric
deposition of mercury, lead, and organic contaminants (light fraction polynuclear
aromatic hydrocarbons or PHAs).
» , Suspended and resuspended sediments that increase turbidity and decrease light
penetration to eelgrass beds, and can weigh down eelgrass blades both directly and
by increasing epiphyte weight; and, as a result of loss in eelgrass, a shift in
deposition.
> Physical alteration of estuarine habitat including increased sediment disturbance,
, bottom disruption, and shading from dock construction; mechanical disruption from
clam digging, boat propellers, and moorings, and habitat fragmentation that results
from these activities. . . .
> Altered flow or hydrologic modification where the flow volume, velocity, and path
of rivers results in loss of spawning habitat for anadromous fishes.
* Finfish harvest pressure, which directly affects fish mortality in offshore species .
from commercial fishing activities, and recreational fish in freshwater rivers and
ponds. , .
> Eelgrass wasting disease caused by the slime mold (Labyrinthula), which can act
synergistically with stress on eelgrass from reduced light conditions.
DRAFTJune 13, 1996 - 13
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Table 3. Nitrogen loading to water table, chlorophyll concentrations, and mean (± standard deviation)
biomass of macrophytes in three selected subestuaries of Waquoit Bay (Adapted from Valiela et al.
1992).
Subwatershed
Childs River
Quashnct River
Sage Lot Pond
N" loading to water table
(kgNyr1)
14209
14534
331.5
Chlorophyll
concentrations at mouth
(mgnr3)
' 25.5 ± 7.6
5.9 ± 1.7
3.9 ±1.2
, Total macroalgal
biomass (g m-2)
. ' 335 ± 39.8
150 ± 14.3
90 ± 12.1
Eelgrass biomass
fenr2)
0
o
117±12.6;;
2:2 Assessment Endpoint Selection
The Team's selection of assessment endpoints" was based on societal values expressed in the
management goal and objectives, as-well as an evaluation of available information to ensure that the
endpoints were ecologically relevant in the watershed and were susceptible to the identified
stressors. The assessment endpoints'are measurable attributes of valued resources that include both
an entity (e.g., eelgrass) and a measurable attribute (e.g. areal extent). They provide direction for ,
the assessment and are the basis for the development of questions, predictions, models, and
analyses. The Team's identification of an assessment endpoint does not imply that data currently
exist in Waquoit Bay to quantify attribute changes. Assessment endpoints are only required to
support the ability to collect data for quantification.
2.2.1 The Assessment Endpoints
Eight assessment endpoints were selected to represent estuarine and freshwater components of the
ecosystem and ecological and human health concerns. In some cases overlap among assessment
endpoints was recognized and endpoints were combined or eliminated later in the process. The
assessment endpoints selected for the Waquoit Bay watershed ecological risk assessment include:
> Estuarine eelgrass habitat abundance and distribution
» Resident and juvenile nursery estuarine finfish species diversity and abundance
> Clam and other benthic invertebrate diversity, abundance, and distribution
> Migratory brook trout and alewife herring reproduction
> Freshwater stream benthic invertebrate diversity and abundance
* Freshwater pond trophic status
» Water-dependent wildlife species feeding and nesting habitat
. * Bacterial and contaminant content of fish and shellfish
14
Waquoit Bay Watershed Ecological Risk Assessment
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2.2.2 Endpoint Description and Rationale
Assessment endpoints were selected based on three criteria: how well they represent the ''-.'
management goal (societal value), how well they represent ecological integrity in the ecosystem
(ecological relevance), and how likely they are to be exposed to and adversely affected by known
stressbrs (susceptibility). To judge societal value, each endpoint was evaluated relative to the 10
management objectives identified during planning (Table 1, Section 1.1.2). Table 4 shows which
management objectives each endpoint addresses. Ecological relevance and susceptibility were both
evaluated based on available information on ecosystem structure and function and known and
predicted stressors. In the descriptions below.on the assessment endpoints, the rationale for
selection based on these three selection criteria is provided. ".. '
Table 4. Relationship of assessment endpoints to management objectives.
Assessment Endpoint
Estuarine eelgrass habitat abundance and
distribution
Estuarine Finfish Species diversity and
abundance . .
Benthic invertebrate diversity,
abundance and distribution
Freshwater Migratory fish reproduction
Stream benthic invertebrate diversity
and abundance
Freshwater pond trophic status
Water-dependent wildlife species
feeding & nesting habitat
Bacterial & contaminant content of fish
and shellfish
Management Objective :Number
1
X
X
'2
X
X
X
X
X
X
X
3
X
X
X
X
x
4
X
X
X
-
5
' X
X
6
X
7
X
X -
X
' .
8
X
X
9
X
X
10
X
Considerable overlap and interdependence among objectives and potential endpoints are
recognized. For example, objective 5 (reestablishment of scallops) would require achieving
objective 1 (elimination of hypoxia), objective 2 (prevent toxicity) to prevent scallop death,
objective 4 (re-establishment of eelgrass), and objective 7 (eliminate macroalgae) to provide
suitable habitat. Objective 4 (juvenile scallop habitat) would require achieving objective 7
(eliminate macroalgae) because local hypoxia (objective 1) is caused by decaying algae, at the
bottom of the mats, and macroalgae shade and replace eelgrass. This type of evaluation was used
to identify multiple sources of stress and the variety of possible pathways for loss of an ecological
value. The objective is to identify the complement.of necessary and sufficient conditions for
achieving management goals. ,
DRAFTJune 13, 1996
15.
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Each assessment endpoint is described below to highlight its characteristics as they relate to
ecological relevance, susceptibility to known stressors, and societal value, with specific reference
to the management objectives.
Estuarine eelgrass habitat abundance and distribution. Eelgrass (Zostera marina) is a rooted
vascular .plant that grows subtidally on mud to gravel bottoms in zones of fast-moving or quiet
waters where salinity ranges between 20 and 32 parts per thousand. Eelgrass roots and rhizomes .
decrease erosion and increase sedimentation. Eelgrass blades promote deposition by interrupting
water flow, and trapping suspended sediments and paniculate organic matter, thereby adding to the
available food within the meadow (Short, 1984, 1989).
Eelgrass habitat abundance and distribution was selected as an assessment endpoint. because
eelgrass beds provide prime living, feeding, and nursery habitat for a large and significant aquatic
community including juvenile scallops, invertebrates, and forage fish that sustain larger fish species
(Heck, 1989; Thayer et al., 1989; management objectives 3 and 4). Eelgrass is highly susceptible
to water quality conditions and requires clear waters with ample light penetration for
photosynthesis. Shading by algae and suspended sediments directly impacts eelgrass growth.
Excessive growth of macroalgal mats has displaced eelgrass in Waquoit Bay (objective 7).
Abundance and distribution were selected as measurable attributes of eelgrass to represent estuarine
condition. Existence of eelgrass is one of the best indicators of estuarine quality, and the presence
of a diverse aquatic community (e.g., greater species diversity and abundance was found in
eelgrass beds compared to adjacent unyegetated areas in Waquoit Bay and Nauset Marsh on Cape
Cod (Valiela et al., 1992; Heck et al., 1989)). Measures of quality and density were not chosen
for eelgrass attributes because of the greater difficulty in obtaining information on plant species
composition, shoot density, and blade stature. Although these variables influence physical
structure,, food availability, and physical suitability of these areas for fish, in the absence of
toxicity, the presence of eelgrass beds is the best indicator of the presence of a diverse estuarine
'aquatic community. Both eelgrass and several eelgrass dependent and commercially important
species have declined precipitously since the 1950s.
Resident and juvenile estuarine finfish species diversity and abundance. The estuarine finfish
community contains resident and transient, arid demersal and pelagic species. Fifty-two species
have been collected in Waquoit Bay. Of these, muminichug, striped killifish, tidewater silverside,
fo'urspme stickleback, and rainwater killifish constitute 35 percent of the total taxa, and dominate
the abundance (46 percent) and biomass (41 percent) of the overall finfish community (Ayvazian et
al., 1992). Part-time residents represent a composite of estuarine spawners (e.g., whiter flounder
and tautog); marine species that are estuarine visitors (e.g., sand lance, summer flounder, and
American pollack); nursery species or young-of-the-year (e.g., winter flounder juveniles, mullets,
juvenile* tautogs, menhaden, Atlantic silversides, bluefish, and bay anchovy); and adventitious
species that have a more southern distribution but lack an apparent estuarine dependence (e.g.,
lady fish, halfbeak, and crevalle jack). > _ ;
Resident and nursery finfish were selected for the assessment' endpoint because of their importance
to commercial and recreational values, their significance to the aquatic community, and their
susceptibility to localized impacts on habitat quality. Finfish are susceptible to hypoxic and anoxic
conditions (e.g., summer anoxia or hypoxia may impact winter flounder juveniles and
mummichugs, objective 1) and toxic contaminants (objective 2). The loss of eelgrass habitat
encompasses a decrease in coverage, a decrease in density of stems, the displacement of eelgrass
by macroalgae, or the conversion of eelgrass meadow to open bottom with sand or mud sediments.
16 Waquoit Bay Watershed Ecological Risk Assessment
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Macroalgal mats are less suitable than eelgrass as a refuge for finfish, and the bottom of the
macroalgal mat may be hypoxic (objectives 4 and 7). Diversity and abundance of resident and
nursery finfish were selected as attributes because these measures represent the existence of
conditions^ that support survival, reproduction, and recruitment (objective 3), and some data are
also available. Feeding, hiding, reproduction, and recruitment would be important attributes to
measure in future studies. ' ' .
t
Commercially harvested marine and estuarine adults are not included. They are susceptible to
offshore as well as inshore stressors and therefore reflect more regional impacts resulting from
harvest pressure, coastal eutrophication, and long-term climate change. These groups were not,
selected as part of the assessment endpoint because nursery species and year-round resident finfish
are.better indicators of localized impacts on habitat quality. If resident and nursery species are
protected, it is assumed that marine species will also be protected from habitat degradation.
Clams and other benthic invertebrate diversity, abundance, and distribution. Clams and other
benthic invertebrates in Waquoit Bay provide major food sources for resident and transient finfish
and water-dependent wildlife. Hardshell and softshell clams currently support an important
recreational and commercial fishery. Scallops are ho longer harvestable. The benthic community
can be adversely affected by loss of eelgrass,.toxic and hypoxic conditions and macroalgal mats
.(objectives 1, 2, 4, 5 and 7). Shellfish and other benthos are also sensitive to the degree of
sedimentation hi breeding areas, the presence of critical habitats such as eelgrass beds and wetlands
(objective 4) and the extent of recreational and commercial harvesting mortality, including catch
and by-catch (objective 5). The presence of eelgrass beds and sufficient water quality are thought to
be the. critical elements for supporting the appropriate habitat to maintain and promote a diverse
and abundant estuarine benthic faunal community.
\ . . '
Scallops are principally found hi eelgrass beds and hardshell arid softshell clams inhabit sandy open
areas. Since these species are found in different bottom habitats, their abundance and distribution
are a good reflection of ecosystem function. Although scallops are specified in management
objective 4, they were not explicitly selected as an assessment endpoint because then- numbers
fluctuate widely in nature,, and the absence of scallops cannot be interpreted to mean that the known
environmental requirements for scallops are not being met. Since, epifaunal invertebrates settle on
eelgrass blades and some infaunal invertebrates occur in greater abundance within eelgrass beds,
the eelgrass-associated benthic community is being used to represent the ecological requirements
for scallops which settle on the blades during then-juvenile phase before settling as adults on the
surface of the sediments. .
Migratory brook trout and alewife herring reproduction. Migratory fish, including anadromous
brook trout and alewife herring, use the Waquoit Bay watershed as breeding grounds. Migratory
fish provide for a highly valued recreational fishery that has been in decline. The Quashnet River
was a prized trout'stream, with anadromous or "sea run" brook trout or "salters" in the 1800s. By
1950, industrial and then agricultural demands had destroyed then- breeding habitat. It has taken
years of effort by Trout Unlimited and the Massachusetts Division of Fisheries and Wildlife to
reestablish breeding habitat hi about 1.5 miles of the river. The trout species that rely on this river
for spawning are susceptible to water quality changes. They depend.on swiftly flowing, cold
waters that are high in dissolved oxygen. Alewife herring, which travel to John's Pond to spawn,
rely on .sufficient water depth to traverse the bogs near the pond.. Drops in the water table or
reduced flow can prevent access to spawning areas. The Quashnet River and the ground water that
feeds it might be tapped for drinking water, possible leading to changes in water quantity while
urban development could lead to further water quality problems.
DRAFTJune 13, 1996 " ' . '. 17
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Trout and alewife are sensitive representatives for other migratory finfish:. Protecting the ability of
migratory finfish to reach freshwater rivers and ponds and find habitat and water quality
appropriate for spawning and egg survival meets the management goals for streams and ponds
(objectives 2 and 9). Reproduction of migratory fish was selected as the attribute because the key
function that the freshwater portions of the watershed provide to migratory fish is reproductive
habitat. This attribute is particularly susceptible to the types of stressors likely to impact migratory
fish in this watershed. . , . ..'.'..
Freshwater stream benthic invertebrate diversity and abundance. Stream benthic invertebrates
serve as a needed food source for migratory and resident fish. Like, migratory fish, benthic
invertebrates need swiftly flowing, highly oxygenated, high-quality water for their habitat. Benthic
invertebrates are excellent indicators of water and sediment quality because they spend most of
their life cycle in the stream (often in restricted locations or habitats) and are particularly
susceptible to toxics (objective 2), eutrophication effects (objective 8), and sedimentation. Societal
value is based on the value of native species (objective 9) and the support the benthic aquatic
community provides for fish species (objective 3).
Freshwater pond trophic status. Changes in the tropic status of kettle ponds serve as an indicator
of water quality and directly affect ecosystem function (objectives 2 and 8). The susceptibility of
ponds to increasing nutrient loads makes this assessment endpoint the best indicator of pond shifts
from oligoatrophic to eutrophic status and also addresses community interest in recreational use of
the ponds for swimming, fishing, and aesthetic enjoyment.
Water-dependent wildlife species feeding and nesting habitat. Many avian species, including the
piping plover, least tem, and roseate tern, nest or forage along the barrier beaches of Waquoit Bay.
Other important wetlands in the Waquoit Bay watershed include the salt marshes surrounding the
bay and its tributaries, the coastal ponds, and the shorelines of Ashumet and Johns Ponds.
Waterfbwi are the most societally important wildlife'solely dependent on wetlands for breeding,
feeding, and migratory needs. Within the ponds, a high diversity of phytoplankton and abundant
invertebrates provide food for finfish' which, in turn, are prey for osprey. Several avian species
that use the ponds are of special concern or threatened, including the marsh hawk and grasshopper
sparrow. These species have high societal value. They are susceptible to toxic pollutants
originating from MMR, cranberry bogs, and urban development (objective 2). They are also
susceptible to habitat loss, both from direct destruction of habitats, and lexicological and
hydrological changes that may influence habitat type, quality, and quantity. Significant numbers of
bird and mammal species use wetlands and freshwater resources around the ponds and rivers for
feeding and nesting. Maintenance of supporting wetland habitats was considered appropriate for
meeting management objective 10.
Bacterial and contaminant content offish and shellfish. The aquatic community of fish and
shellfish provides significant recreational and commercial benefits to humans and other organisms
in the watershed. Increasing incidents of shellfish bed closures to harvesting because of high
bacteria counts are of considerable concern to commercial and recreational interests in the .
watershed (objective 6). Increasing evidence of malformations in resident freshwater fish hi ponds
now being contaminated by ground water plumes flowing from the MMR Superfund site are cause
for concern, although studies are preliminary and no evidence of chemical contaminants as the
caude has been demonstrated (objective 2). Contamination is expected to increase and might be a
problem now. %
18 " Waquoit Bay Watershed Ecological Risk Assessment
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2.2.3 Overlap of Assessment Endpoints and Their Application to the Risk Assessment
' - . / ' ' '.
These assessment endpoints are used to represent ecological values in the watershed that support
management goals. During their selection considerable discussion occurred to determine whether
this set of endpoints was sufficient, redundant, or excessive. Several endpoints may be considered
redundant but were not eliminated before conceptual model development because of possible
insights their use could provide during hypothesis generation and model construction. The team
recognized some redundancy but felt that the set best covered the diversity of ecological values and
stressors impacting the watershed.
Selection of which assessment endpoints to follow through to analysis occurred during the
development of the conceptual models and in the planning of analyses. In some cases only limited
4ata or information is available on an assessment endpoint so for the purposes of this risk
assessment, that assessment endpoint can only serve as a focal point for conceptual model
development. However, for planning future research the assessment endpoint serves a significant
function in defining what research needs to be done in the watershed.
2.3 Conceptual Model Development
The conceptual models developed for the Waquoit Bay watershed represent a series of risk
hypotheses about the relationships between particular stressors and ecological effects expected to be
observed in each assessment endpoint., Models were developed at several levels of complexity and
were done interactively. The general watershed conceptual model (Figure 2) is a broad
representation of relationships among human activities in the watershed (sburces), the stressors
believed to occur as a result of those sources, and ecological effects likely to occur in each of the
assessment endpoints. Shown within the conceptual model are possible measures to evaluate
response. Second-level models focus on particular assessment endpoints and show multiple
stressors, potential exposure pathways and expected ecological responses, '
2.3.1 Watershed Conceptual Model
The watershed-level conceptual model diagram illustrates connections among sources of stressors,
stressors, effects, and assessment endpoints in the Waquoit Bay watershed. The diagram is
organized around system stressors. Each stressor-has a coded line type that illustrates a pathway
connecting its sources to effects and endpoints. Each of the components of the model is
represented by a different figure to aid interpretation (see key). This is a broad-based model that
provides a framework for the risk assessment and aft overview of ecosystem processes. The
diagram shows only stressors and effects thought to occur in the Waquoit Bay watershed. It does
not show the relative importance or magnitude of the stressors or effects. More detailed conceptual
models were developed to evaluate multiple stressor effects and exposure pathways for specific
assessment endpoints. These were generated as a result of detailed risk hypothesis development
(see Section 2.3.2).
Key to Models:
/
Figure
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Double-line diamond
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Component
Source of Stressor '
Primary ecological effect
Measurement
Figure
Ellipse
Diamond ' « ;
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Assessment endooint
DRAFTJune 13, 1996
19
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20
Waquoit Bay Watershed Ecological Risk Assessment
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sjujodpug
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Figure 2. Waquoit Bay watershed conceptual model (continued).
DRAFTJune 13, 1996
21
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Shown at the top of the model are five major human activities (agriculture, atmospheric deposition,
residential development, industry, and marine activities). Within each of these major activities are'.
one or more specific activities that serve as sources of stress in the watershed. For example,
residential development results in housing and road construction, installation of septic systems,
installation and maintenance of lawns and gardens, and construction of wells.
For each activity or source identified there are potentially one or more stressors that might exist in
the watershed system. For example, nutrients serve as one major system stressor in Waquoit.
However, sources of nutrients in this system are many and include fertilizer application,
automobiles, lawn and garden maintenance, septic systems, impervious surfaces, and sewage
treatment plants. The next level in the diagram shows predicted and observed ecological effects
believed to result from exposure of the ecosystem to stressors. Represented here are several
cascading effects. For example, nutrients can lead to algal growth, which contributes to increased
chlorophyll in ponds and siltation, shading, and low dissolved oxygen hi estuaries. These
responses can lead to loss of eelgrass, suffocation of aquatic communities, habitat loss, and
eutrophication with increased production of organic matter.
The potential adverse effects of one stressor can to affect one or many assessment endpoints.
Nutrients, nitrogen of phosphorus can be traced to six assessment endpoints including freshwater
benthic invertebrates, trophic status of ponds, pond fish community, eelgrass habitat, and estuarine
benthic and finfish communities. In some cases indirect effects might not be represented here, but
would be shown in the specific pathway conceptual models for a single assessment endpoint or a
single stressor (e.g., although water-dependent wildlife are not connected to the nutrient matrix,
nutrients affect the fish and invertebrate communities on which wildlife feed). Assessment
endpoints for which appropriate data could prove difficult to obtain are identified later in the
process but are represented in the conceptual model. . .
''.'
The watershed-level conceptual model diagram features seven stressors:
Toxic chemicals. Sources of toxic chemicals are agricultural pesticides, atmospheric deposition
(metals and organics from automotive and industrial emissions), suburban lawn and garden
chemicals, point sources (solvents and aviation/jet fuel derivatives in the MMR plumes),
impervious surfaces (metals and hydrocarbons in road and roof runoff), and docks and marinas
(metals and hydrocarbons from antifouling substances and boat motors). The toxic chemicals may
affect aquatic animal life: migratory fish, pond fish, freshwater benthic invertebrates, estuarine
benthic invertebrates, and estuarine fish.
Altered flow. Stream flow might be altered by flow control structures built for cranberry bogs, by
groundwater depletion from well pumping, and by runoff from impervious surfaces., Altered flow
can change the timing and magnitude of floods and low flow, as well as the amount of fish and
invertebrate habitat available in streams, and riparian wetland area. Migratory .fish, stream benthic
invertebrates, and wetland-dependent wildlife that depend on these habitats might be adversely
affected.
Resuspended sediments. Several watershed activities might contribute suspended sediment to the
estuary or resuspend sediment in the bay. Activities that might contribute sediment include
construction (all) and impervious surfaces (particulates in impervious runoff); activities that may
resuspend sediment hi the bay include construction of docks, boating, dredging, and shellfishing.
Suspended sediment might contribute to siltation and shading of eelgrass.
22- . . Waquoit Bay Watershed Ecological Risk Assessment
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Nutrients. Sources of nutrients include agricultural and suburban fertilizers, atmospheric ,
deposition of nitrogen oxides, domestic septic systems, and wastewater treatment facilities. The
primary effect of nutrient loading is growth of algae, principally phytoplankton in the ponds and ,
macroalgae and periphyton in the estuary. Increased algal production increases the trophic state of
the ponds and can contribute to hypoxia in both ponds and the estuary, with ultimate effects on
invertebrates and fish, In the estuary, algal growth contributes to shading of eelgrass by
macroalgae and periphyton, and eventual replacement of the eelgrass by algae. Loss of eelgrass
may in turn cause cascading effects on estuarine invertebrate and fish communities. A more
detailed conceptual model of eelgrass loss is shown in Figure 3 and a detailed conceptual model of
the fmfish community changes is shown hi Figure 4. -
Habitat alteration. Several activities in the watershed result in alteration of aquatic habitats.
Construction activities might cause temporary or permanent habitat changes if the construction is in
or near an aquatic habitat. Docks and piers are a permanent alteration of the aquatic habitat.
Boating, dredging, and shellfishing might directly disturb eelgrass habitat and injure plants. Beach
protection (jetties and groins) changes sediment transport and beach dynamics, potentially altering
the barrier beach habitat. These alterations to streams, wetlands, barrier beaches, salt marshes, and
.eelgrass beds might adversely affect the organisms in those habitats.
Disease. Eelgrass. wasting disease (Labyrinthula) is the only stressor hi the conceptual model with
no known anthropogenic source. It has a direct effect on eelgrass cover and hence has indirect
effects on estuarine invertebrates and fish.
t * ' ' -
Harvest pressure. Harvest pressure includes fishing for freshwater fish, estuarine fish, anadromous
fish, and shellfish and affects only those groups.
For the purpose of focusing on specific parts of this watershed, Figure 5 shows these pathways for
the stream component, Figure 6 shows pathways for the pond component, and Figure 7 shows
pathways for the estuarine component. Each of these pathways was created based on assumptions,
or risk hypotheses, about how stressors are affecting or are expected to affect targeted assessment
endpoints. They were derived from available information on the watershed gathered early hi the
problem formulation process and on a continuing basis, from ecological theory on how systems
function, and from relationships established in other watersheds that are expected to be consistent
from one geographic area to another where similar systems exist.
DRAFTJune 13, 1996 23
-------
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Figure 3. Eelgrass conceptual submodel (continued).
DRAFTJune 13, 1996
25
-------
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Figure 4. Finfish community conceptual submodel.
26
Waquoit Bay Watershed Ecological Risk Assessment
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Source*
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Figure 4. Finfish community conceptual sumodel.
DRAFTJune 13, 1996
27
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DRAFTJune 13. 1996
29
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30
. 'Waquoit Bay Watershed Ecological Risk Assessment
-------
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Figure 6. Waquoit Bay pond conceptual model (continued).
DRAFTJune 13, 1996
31
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es
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DRAFTJune 13, 1996
33
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2.3.2 Risk Hypothesis Development
The watershed conceptual model illustrates that each stressor might affect several endpoints and '.
each endpoint might be influenced by several stresstirs. Since assessment endpoints provide the
focus for this risk assessment and the intent of the assessment is to assess the risk of multiple
stressors on a particular assessment endpoint, the following discussion on risk hypotheses is divided
by endpoint. This approach provides the foundation for evaluating the cumulative and combined
risk of more than one stressor. To understand how assessment endpoints are being affected by
these stressors, however, it will be necessary to evaluate alternative exposure pathways of a
stressor from different sources. Stressor pathways are evaluated through additional conceptual
models.
The following risk hypotheses for eelgrass habitat abundance and distribution and finfish diversity ,
and abundance are expressed as narratives about how assessment endpoints might become exposed
and respond to one or more stressors. Background information that supports these hypotheses is
available in Appendix E.
Development of conceptual models and risk hypotheses for the remaining six assessment endpoints
is ongoing, but they are not ready for presentation at this time. The models developed for eelgrass
and finfish provide a basis for determining how best to present information and develop the process.
The conceptual models represent considerable information, but in many cases data are not available
at this time to conduct an evaluation of posed hypotheses and predictions for these two endpoints.
They are presented to allow managers and scientists in the watershed to consider potential research
that will provide the basis for pursuing a more complete risk assessment. Further analyses of
available data will allow the Team to refine hypotheses for the these and the other endpoints.
Eelgrass Habitat Abundance and Distribution: Risk Hypotheses and Conceptual Models.
The conceptual models and risk hypotheses for the eelgrass habitat abundance and distribution
assessment endpoint include sources and stressors, cascading ecological effects, and response
pathways. Eelgrass habitat is the common assessment endpoint for each of the source-to-response
pathways represented in the model. Common measures (eelgrass habitat cover and extent) apply to
each pathway. These measures are depicted outside the direct source-to-assessment endpoint
pathways because they represent the result of ecological response rather than a direct measure of
the response or attributes of the response pathways.
The following discussion is separated into two parts. The first provides predictive hypotheses about.
the effects of primary stressors depicted in the watershed conceptual model (Figure 2). These
hypotheses and predictions are then followed by a descriptive conceptual model and hypotheses on
the multiple pathways for loss of eelgrass from the variety of sources of these stressors and source-
to-response pathways. Each of these pathways is illustrated hi the eelgrass habitat conceptual
submodel (Figure 3).
Stressor Hypotheses
The watershed conceptual model (Figure 2) contains' five primary stressors for eelgrass: nutrients,
sediments, physical alteration of habitat, toxics, and disease. Based on conclusions drawn from
available information, multiple stressor effects have caused eelgrass to decline over the last 40
years. Each stressor has multiple sources. Reduction of one stressor or source is not likely to be
34 Waquoit Bay Watershed Ecological Risk Assessment;
-------
sufficient for reestablishing eelgrass in the bay, although nutrient reduction is a necessary
prerequisite. .
Nutrients. Increased nitrogen loading in estuarine waters causes shading from excess growth of
macroalgae, phytoplankton, and epiphytes. Historical and steady state inputs of nitrogen to ground
water will continue to influence algal growth for up to 100 years. Additional development in the
watershed will add to this nitrogen loading. Light attenuation in shallow estuaries might not be
great enough to eliminate eelgrass altogether, but continuing inputs of nitrogen from current
activities will prevent eelgrass recovery. Sub-bays with the greatest nutrient loads will have more
macroalgae and less eelgrass. Those sub-bays with less nutrient loading will have less macroalgae
and more eelgrass.
Suspended Sediments. Shading from resuspended sediments caused by physical disruption of
bottom sediments results in decreased growth and the death of eelgrass plants.
Physical Alteration of Habitat. Available habitat for eelgrass has changed and will continue to .
change because of (1) loss of appropriate habitat from dock construction; (2) mechanical disruption
from clam digging, boat props, and moorings, which cut eelgrass blades or uproot and kill eelgrass
plants; and (3) subdivision of the meadow as a result of eelgrass death caused by mechanical"
disruption, disrupting community integrity and altering meadow composition.
Toxics. Toxics cause physiological stress on eelgrass plants, leading to slow growth. This could
exacerbate effects from other stressors.
Disease. Slime mold acts synergistically with reduced light to decrease eelgrass growth, and water
currents transport infected eelgrass blades, broken by physical disruption, to new areas.
Predictions: . '','.'
» The replacement of eelgrass beds with fast-growing macroalgae will continue
unless the amount of nitrogen entering the bay is reduced. Reestablishment of
eelgrass will require reduction of nutrients.
> Reestablishment of eelgrass from'reduced nutrient loading will occur only over a
long time period to account for the time travel of nutrient laden ground water to the
Bay, .- - .''.' " ..''' -
* . Reduction of nitrogen is a necessary but not sufficient requirement for eelgrass re-
establishment. Habitat alteration from physical disruption will need to be reduced
or confined to specific areas to allow reestablishment.
> The co-occurrence of wasting disease,, toxics, and reduced water clarity might
result in the complete elimination of eelgrass from the Waquoit Bay system.
Complete elimination means that replanting might be the only means of
reestablishing eelgrass meadows. -
Conceptual Model '
The primary stressors have multiple sources. The opportunity to reduce these sources of stressors
are of primary management concern. The hypotheses below describe the eelgrass specific
DRAFTJune 13, 1996
35
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conceptual model to illustrate the multiple ways eelgrass can be lost from this system and to
provide insights on where management action is most feasible. This discussion provides the basis
for the conceptual model diagram shown hi Figure 3. '
Disease. The marine slime mold, Labyrinthula, causes "wasting disease." It is opportunitistic and
likely to cause infection in stressed populations in more saline waters. The infection of eelgrass
located in higher-salinity areas of Waquoit Bay leads directly to loss of eelgrass by death of infected
individuals. Exposure pathways for the disease are not known; however, salinity influences
infection such that eelgrass hi areas of lower salinity is less likely to be infected. These areas are
important for reestablishment.
Nutrients. Nitrogen is the primary nutrient of concern in the estuary. Nitrogen potentially enters
the bay through multiple pathways including ground water discharge, air deposition, point source
discharges, and impervious surface run-off. Exposure pathway analysis by Valiela et al. (1992)
suggests that the principal pathway is via groundwater from septic system inputs (Appendix E,
Figure E-6). The resulting increase in surface water and sediment nitrogen concentrations leads to
increased growth of epiphytes, macroalgae, and microalgae. Epiphyte growth on eelgrass leaves
decrease light availability by shading and increases leaf effective surface area, causing possible
weighting and burial of eelgrass from increased siltation on leaves. Increased"growth of macroalgal
mats leads to direct shading of eelgrass and decreased light penetration. Phytoplankton growth
increases water turbidity, decreasing light penetration to eelgrass. Algal growth also contributes to
increased organic sediment, which might be resuspended by physical disruption (below) and
contains a reserve of nutrients.
Construction and Recreational Activities. Boat propellers impinging on bottom sediments;
dredging; construction of docks, piers and marinas; clam raking; mooring; and erosion in the
watershed cause increased suspended sediments or resuspension of bottom sediments.
Hydrogfaphic conditions (e.g., wave amplitude, frequency, and direction; current velocity) act as
forcing functions that can increase.water turbidity. Turbidity increases shading and decreases light
penetration. This leads to reduced eelgrass photosynthesis, growth decline, and death of eelgrass.
It also causes siltation onto eelgrass leaves, compounding the effect of epiphyte growth discussed in
the previous pathway. . . .'.',.
Docks and Piers. Docks directly block light and reduce available habitat for eelgrass, leading to
reduced eelgrass photosynthesis and loss of shaded eelgrass. Docks and piers also provide the basis
for increased boat traffic, which leads to disturbance of sediments and increased turbidity hi areas
around the docks and piers. Great River, a tributary in the Waquoit Bay watershed, will show a
loss of eelgrass in correlation with increased dock building.
Lawn Care, Agricultural, and Industrial Activities. Care of residential and commercial property
lawns, agricultural activities (e.g., cranberry bogs), and industrial activities (e.g., MMR) hi the
watershed are a source of a variety of toxic chemicals. These may cause physiological stress hi
eelgrass, leading to reduced growth and.death of eelgrass plants. Exposure pathways and effects
from these sources of potential stress are little known.
Boat Propellers, Clam Rakes, Moorings. Boat propellers, clam rakes, and nwporings directly
disrupt bottom sediments, causing physical alteration of habitat and mechanical destruction of :
eelgrass blades, resulting hi death or stress to the plant. Repeated activities without sufficient
recovery tune will result hi decline hi eelgrass beds because of direct loss, of plants, and from the
creation of small patches, increasing vulnerability to other.stressors (e.g., storm events). Boating
36 Waquoit Bay Watershed Ecological Risk Assessment
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activities that churn up bottom sediments will increase the amount of suspended sediments,
increasing turbidity and decreasing light penetration to eelgrass beds. Epiphytes growing on '.
eelgrass blades provide good depositional surfaces for-suspended solids and can weigh down the
eelgrass blades causing them to sink to the bottom where they die from insufficient light or
suffocation (Short, 1989).
. / - " '
Resident Estuarine Finfish Diversity and Abundance: Risk Hypotheses and Conceptual Model
The conceptual models and risk hypotheses for the resident finfish diversity and abundance
assessment endppuit mclude sources and stressors, cascadhig ecological effects, and response
pathways. Resident finfish is the common assessment endpoint for each of the squrce-to-response
pathways represented in the model. Common measures (diversity and abundance) apply to each
pathway. These measures are depicted outside the direct source-to-assessment endpoint pathways
because they represent the result of ecological response rather than a direct measure of the response
or attributes of the response pathways. , ,
The following discussion describes the principal stressors represented in the watershed conceptual
model (Figure 2) and specific predictions to consider. This is followed by the presentation of the
finfish conceptual model and descriptive hypotheses about relationships depicted hi the model.
Stressor Hypotheses
Multiple stressor effects are resulting in lowered reproductive success of adult resident finfish, as
well as lower survival of eggs and juvenile finfish. Each stressor has multiple sources.
Determining the relative contribution of these stressors will be important for setting management
priorities. .
Nutrients. Increased nitrogen loads alter finfish diversify and abundance through excessive
macroalgal growth, which results hi (1) loss of eelgrass habitat for breeding, feeding, and hiding
and (2) hypoxic and anoxic conditions that result in physiological stress, exposure to predation, and
suffocation.
Suspended Sediments. Increased sediment in the water column alters finfish breeding, feeding,
and hiding habitat by (1) reducing growth of eelgrass, (2) covering available habitat, (3) smothering
eggs and juveniles, and (4) reducing feeding success of visual predators.
Physical Alteration of Habitat. Development of land adjacent to prune finfish nursery habitats
causes a direct loss of available nursery areas and contributes to sediment and nutrient loading hi
the vicinity of nursery areas. Direct physical alteration of nursery areas from dredging, boat prop
disturbance, and changes in flow patterns from inlet changes and armoring of coasts alters quality
or removes habitat from potential use.
Toxic Chemicals. Multiple sources of toxic chemicals from pesticide application, air pollution,
lawn maintenance, point source discharges, nonpoint runoff and chemicals used on docks and boats
combine to alter survival and reproduction of juvenile finfish. Stress from hypoxic and anoxic -
conditions exacerbates the effects of toxicity.
Harvest Pressure. Recreational fishing removes reproductive adults from the population of resident
finfish. Although offshore fishing alters the available adult stock returning to Waquoit Bay, this
reflects, regional impacts and no hypotheses are pursued for this portion of the finfish community.
DRAFTJune 13, 1996 37
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Predictions: .
> Loss of eelgrass habitat (from multiple stressors) will favor species associated with
open-water, nonvegetated habitats such as Atlantic silverside, adult summer
flounder, and winter flounder as well as rock crabs and green crabs, over those
species associated with vegetated habitats such as tidewater silverside, juvenile '
summer flounder, grass shrimp, rainwater killifish, juvenile tautog, fourspine
stickleback, and striped killifish.
> Loss of eelgrass habitat and projected changes in the functional aspects of the
finfish community will result in (1) increase in omnivores; (2) decline in top
carnivores; (3); shift from benthic to pelagic habitats; (4) decline in total number of
species, estuarine spawner species and estuarine resident species; (5) increase in.
disease incidence and morphological abnormalities; (6) decrease hi eelgrass habitat
quality prior to physical habitat loss; (7) increase hi dominance of eutrophic
tolerant species where dominance represents the number of species accounting for
90 percent of the total numbers or biomass; and (8) higher fish density and biomass
(abundance) hi medium-quality compared to low-quality habitats (Deegan et al.,
1993). .
> Increasing contaminant inputs from recreational activities.and future toxicity from
contaminated ground water plumes from MMR will increase abundance of tolerant
species and increase incidence of finfish malformations and disease.
* Anoxia and hypoxia will slow the growth, maturation, and reproduction of sensitive
finfish (e.g., Atlantic silversides, juvenile whiter flounder, and juvenile tautogs
versus mummichogs).
Conceptual Model
The primary stressors have multiple sources. The opportunity to reduce these sources of stressors .
are of primary management concern." The hypotheses below describe the finfish conceptual model-
to illustrate the multiple ways finfish diversity and abundance are likely to change and to provide v
insights on where management action is most feasible. This discussion provides the basis for the
conceptual submodel diagram shown hi Figure 4. .
Recreational and Commercial Fishing. Estuarine and offshore fishing remove reproductive aged
fish from the population. This mortality will exacerbate other losses to adults, juveniles and eggs
from other stressors and can change the dynamics of the finfish community resulting hi shifts,hi
competition, feeding patterns and other behaviors.
Nutrient Loading. Nutrient loading increases algal production hi the estuary. Increased
production leads to increased organic matter loads and increased respirational oxygen demand,
resulting hi periodic oxygen stress and occasional fish kills on warm, cloudy, calm days in summer,
when the bay may stratify. Nutrient loading also might lead to loss of eelgrass (see eelgrass
conceptual submodel Figure 3). Ee.lgrass beds are a nursery area for juvenile finfish; hence, loss of
eelgrass may lead to declines hi fish recruitment and fish populations.
Toxic Chemicals. Toxic chemicals from lawns, agriculture, impervious surfaces and the MMR
plumes might cause direct morbidity and mortality of resident finfish hi ill age classes although
38 Waquoit Bay Watershed Ecological Risk Assessment
-------
some age classes could.be more susceptible. Toxic chemicals also might lead to loss of eelgfass
(see eelgrass conceptual submodel Figure 3). Eelgrass beds are a nursery area for juvenile finfish;
hence, loss of eelgrass might lead to declines in fish recruitment and eelgrass dependent fish
populations.
Sediments, Physical Alteration and Disruption. These stressors all can lead to loss of eelgrass (see
eelgrass conceptual model Figure 3). Eelgrass beds are a nursery area for juvenile finfish; hence,
loss of eelgrass can lead to declines in fish recruitment and fish populations. These stressors might
also lead to loss of salt marshes through direct alteration. Salt marshes are spawning and nursery
areas for several estuarine finfish and forage fish, hence, loss of salt marshes might lead to declines
in fish recruitment and fish populations.
2.4 Analysis Plan
The large number of assessment endpoints identified in this risk assessment required a preliminary '
evaluation of overlap among endpoints. .A comparative risk analysis was used to help define which
stressors, assessment endpoints, and relationships should be examined further. To do. this ".
preliminary analysis, stressors were ranked in terms of potential risk to all resources hi the
watershed. The following comparative risk analysis was conducted by the risk assessment team
and is considered preliminary. It requires additional verification and peer review by scientists in
the watershed. . . ' '
The comparative risk analysis identified nutrient loading as the single most important stressor hi
aquatic habitats of the watershed. Accordingly, the team decided to focus subsequent analysis on
nitrogen loading and eelgrass in the estuarine portion of the system.. This analysis is twofold: 1)
" development of empirical models to predict response of eelgrass habitat to nitrogen loading; and 2)
development of models to predict nitrogen loading (from all sources) hi the future as suburban
development proceeds and as management actions are implemented.
Following discussion of the development of predictive models, the remainder of the analysis plan
discusses potential analyses that might be conducted to examine risks from other stressors that are
not the focus of this initial effort.
2.4.1 Comparative Risk Analysis
To conduct a comparative risk analysis, a process called "fuzzy set," which is based on best
professional judgment (Harris et al., 1994; Wenger and Rong, 1987), was used. This approach .
was applied to each endpoint and stressor. The fuzzy set approach is a decision analysis method for
ranking alternatives according to multiple criteria. Applied to ecological risk assessment (Wenger
and Rong, 1987; Harris et al., 1994), stressors are the alternatives and the assessment endpoints are,
the criteria. The analysis then ranks the stressors in order of greatest overall contribution of risk to
the endpomts. .
A preliminary impact matrix for the Waquoit Bay watershed, derived from the.conceptual model, is
shown in Table 5. Each column represents a single endpoint, and each row a single stressor from
the conceptual model. Every connection in the conceptual model from a stressor to an assessment
endpoint is represented by a non-zero cell in the effect matrix (Table 5). Estuarine and freshwater
elements are combined hi this matrix, as they are in the conceptual model. Each cell contains the
effect of a stressor on an endpoint, on, an ordinal scale from 0 (no effect) to 3 (severe effect)
DRAFTJune 13, 1996 . .. 39
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(Harris et al., 1994). For example, the effect of nutrients on eelgrass habitat is given a 3 (severe,
indirect effect), but the effect of physical alteration on eelgrass habitat is given a 1 (slight effect) '
(Table 5). The effect i :" toxic substances on pond trophic state is given a 0, because toxic
substances in the water: tied are not thought to affect pond trophic state (no pathway in the
conceptual model). Values in Table 5 were obtained by consensus among the team, but are
preliminary and have not yet been reviewed by other scientists. '
Table 5. Hypothesized effects matrix; each cell represents relative effect of a stressor on an endpoint.
Stressors
Toxic chemicals
Altered flow
Suspended sediments
Nutrients
Physical alteration
Harvest Pressure
Disease
Migratory
fish
1
2
0
0
2
1
0
Freshwater ;
inverte-
brates ' . .,
1
2
0 ;
1
, 1
0
0
Water- .
dependent
Wildlife:,
0
2
0
0
1
0
0
Pond
: trophic '
status. .
0
0 .
0
3
0
0
0
Contami-
nation
2
0
0
2
0
0
0
Eelgrass
, habitat
0
'0
2
3
1
0
2
Estuarine
inverts- :
brates -.;_ /
'1
0
1
2
1
1
1
Estuarine
fish
1
0
1
2
1
2
1
Rankings were obtained by the difference method, as explained in Wenger and Rong (1987) and
Harris et al. (1994). The effects of each stressor y on endpoint k are subtracted from the effects
of stressor i:
Dkfi>j) ~ xik~xjk (Harris et al. 1994). .
The matrix R = (,/) is an m x m matrix of the sums of the above differences for all endpoints k:
ry = SDk(i,j), i,j = 1,2, ..., m (Harrisetal., 1994).
See Wenger and Rong (1987) for further formulas. The row sums of matrix R were used for
ranking the stressors; the largest row sum was the dominant stressor (Table 5, Base Case). Using
the impacts of Table 5, nutrients were ranked first, followed by physical alteration, altered flow
toxic chemicals, and finally harvest pressure, suspended sediments and disease (Table 6).
Stressors can be weighted by the persistence of the stressors if their input is removed. Persistence
of stressors was ranked on a scale of 1 to 5, where 1 represents almost no persistence, and 5 is an
effect that lasts indefinitely (Table 7). .Altered flow and physical alteration received a persistence
score of 5 because they are permanent changes that do not reverse themselves. Toxic chemicals
and nutrients received a persistence score of 3 because of the time delay in ground water'travel to
reach water bodies. Thus, if sources of either toxics or nutrients were stopped, substances
remaining in the ground water would still affect water bodies for some time. Suspended sediments,
harvest pressure, and disease received a score of 1 because they are all relatively nonpersistent; i.e,
if fishing is stopped, there is no "residual" harvest pressure. Results of the weighting are also in
Table 6 (weighted column). When weighted, the stressors tied previously for third place (altered
flow-, toxics) differentiated into third and fourth place (Table 6).
40
Waquoit Bay Watershed Ecological Risk Assessment
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Table 6. Stressor ranks under three scenarios.
Stressors
Nutrients
Physical alteration
Altered flow
Toxic chemicals
Harvest pressure
Suspended sediments
Disease
Base Case
1
2
3'
3 ' ,
4
4
4
Weighted Stressors
1
2
3 ' -.''.-
4
5''
5
5
Weighted with
Stressor interaction ;
1 -
2
3
4
5
5 .
5
Stressors may interact with one another by exacerbating other Stressors (Harris, et al., 1994).
Interactions among the Stressors'are shown in Table 8. Both members of an interacting pair of .
Stressors receive a score because both must be present for the interaction to work. Interaction
scores were set at 1 because they are plausible, hypothesized relationships, with no information on
their relative strength or actual existence. Nutrients can enhance the effects of both suspended
sediments and disease by causing excess organic floe that can be resuspended, and shaded eelgrass
may be more susceptible to disease. Excess organic floe contributes to sedimentation. Toxic
chemicals may stress eelgrass plants so .that they are more susceptible to-disease. The resultant
rankings reflecting both weighting and interaction (Table 6, rightmost column) were me same as
the weighted scenario only. .
Table 7. Relative persistence of Stressors.
TableS. Interaction among Stressors.
Stressor
Nutrients
Physical alteration
Altered flow
Toxic chemicals
Harvest pressure
Suspended sediments
Disease _
Duration
' 3
5
5
3
1
1
1
Stressor
Nutrients
Physical alteration
Altered flow
Toxic chemicals . .
Harvest pressure
Suspended sediments
Disease
Interaction
1
0
0
1
0
1
1
Ranks were very similar among the three models, showing that the hypothesized effects matrix
(Table 5) was robust to changes in persistence and interaction. Nutrients were always ranked first;
physical habitat alteration was always ranked second. Suspended sediments and disease were
always ranked last. Altered riverine flow, and toxic chemicals, were tied in the middle in the
.unweighted scenario, but when weights were applied they differentiated from each other. The
robustness of the rankings was due primarily to the number of endpoints affected by each stressor:
DRAFTJune 13, 1996
41
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Nutrients and physical alteration each affected six endpoints, and nutrients had two strong effects
on two assessment endpoints (eelgrass'habitat and pond trophic status). The comparative risk
analysis presented here must be regarded as preliminary because the effects matrix (Table,5) has
not at this writing been reviewed and agreed .to by experts and knowledgeable persons on
ecological effects hi estuaries. lathe absence of quantitative data on the relative magnitudes of
effects of the different stressors, expert consensus is required.
2.4.2 Development of a Regional Model of Eelgrass Response to Nutrient Loading
The comparative risk analysis, as well as prevailing scientific opinion prior to the comparative
analysis, indicated that excess nutrient loading,-particularly nitrogen, is the principal stressor
affecting Waquoit Bay estuary, which prevents most of the management objectives-from being met.
More detailed analysis will identify and address critical gaps in the relationship between nutrient
loading and assessment endpoints. This analysis will consist of two parts: determination of the
predictive relationship between nutrient loading and eelgrass cover in estuaries of Cape Cod; and
prediction of future nutrient loading to Waquoit Bay under various scenarios of construction and
buildout.
Although it has been'known for some time that nitrogen loading contributes to estuarine
eutrophication and loss of SAV hi Waquoit Bay and other estuaries of Gape Cod (e.g., Costa 1988;
Valiela et al. 1992; D'Avanzo and Kremer, 1994), predictive relationships between nitrogen
loading or nitrogen sources on the one hand, and the biological response of the estuary on the other
have not been developed for estuaries such as Waquoit. The objective of this analysis will be to
develop the link between estimates of modeled nitrogen loading and predicted ecological effects in
the estuary. . .
The relationship has been examined within Waquoit Bay over tune and among its subestuaries, but
in each case sample size was too small for statistical inference and for estimation of uncertainty
(n=5; Valiela et al., 1992). There is a clear correlation between populatipn growth hi the Waquoit
Bay watershed,' the-decline of eelgrass, and the decline of scallops (Valiela et al., 1992). However,
observations within the Bay and its subestuaries are a form of pseudoreplication because the .
observations, being from a single place, are'not independent (Hurlbert, 1984). Extending the
sample space to include similar embayments of Cape Cod would alleviate the pseudoreplication
problem and would increase sample size to allow estimation of uncertainty. '
Objectives
* Quantify the extent and cover of eelgrass historically and presently hi Waquoit Bay
and in other similar estuaries.
> Estimate nitrogen loading hi Waquoit Bay and in other similar estuaries in the
region.
> Develop an empirical model of the response of eelgrass cover (assessment
endpoint) to estimated nitrogen loading (stressor) hi Waquoit Bay and hi other
similar estuaries.
Submerged, aquatic vegetation (SAV) is a sensitive indicator of eutrophication in estuaries.
(Dennisoh et al., 1993) and is easily monitored with aerial photography. As described hi Section
2.2, eelgrass beds are preferred habitat of juvenile scallops, and are a nursery and feeding area for
42 Waquoit Bay Watershed Ecological fiisk Assessment
-------
estuarine fish. Eelgrass beds can be identified and quantified from aerial images and can be
distinguished from other SAV (e.g., Ruppia, Codiuni) and. from macroalgae and bare sediment.. '
For these reasons, eelgrass cover was selected as a measurement endpoint for eelgrass habitat',-
estuarine fmfish habitat, and estuarine benthic invertebrate (including scallop) habitat.
Justification and approach. The analysis approach for the nutrient hypothesis will be to examine
relationships between eelgrass cover and predicted nitrogen loading using a larger and more
independent sample of similar estuaries throughout Cape Cod, Martha's Vineyard, and Nantucket.
A similar approach was used to develop a predictive model for the estuaries of Buzzard's Bay
(Costa, 1992). The Buzzard's Bay estuaries are open and well-flushed, unlike Waquoit Bay, which
is isolated by a barrier beach and has only a narrow outlet to 'the sea. There are several other
estuaries on Cape Cod, similar to Waquoit Bay, with limited tidal flushing, varying degrees of
residential development, narrow inlets restricting water exchange with open water, and substantial
ground water input from the sandy glacial moraines and till of the region.
The approach will be to develop one or more regression models of eelgrass cover in estuaries of
Cape Cod and the islands. Eelgrass cover in each estuary, digitized from a series of aerial images,
will be the response variable. The principal predictive variable will be nitrogen loading, estimated
for each estuary from one of three extant N loading models (reviewed by Cadmus, 1995), An
alternative model will use watershed, land use directly as a predictive -variable. Sources of nitrogen'
(residential septic systems, lawns, discharges) nearest an estuary are expected to have a
proportionately greater effect on eutrophication and eelgrass cover than distant sources, due to
attenuation of N in groundwater (Valiela et al., 1996) and due to greater travel time from the
distant sources (Sham et al., 1995). This will be modeled by separating near sources from distant
sources as predictive variables in a multiple regression model (see below).
The objective of this exercise is to develop predictive relationships between estimated nitrogen
loadings arid eelgrass cover in Cape Cod estuaries. The central assumption is that the estuaries
behave similarly and that by altering nitrogen loading of a given estuary (i.e., .Waquoit Bay)
eelgrass will respond as predicted by the empirical model. This approach has been successful in
management of eutrophication in lakes arid has been successfully applied to the small estuaries of
Buzzard's Bay, and to larger estuaries such as Tampa Bay (Tampa Bay NEP, 1995). Therefore, it
should also be successful for the estuaries of the South Shore of Cape Cod.
Models for estimating nitrogen loading. There are currently three models (CCC, WBLMER, and
BBNEP) of nitrogen loading for Cape Cod estuaries. Each predicts the total N loading from
measured variables, including the amount and distribution of residential septic systems, .impervious
surfaces, lawns, natural vegetation, atmospheric deposition and other sources. The models differ in
assumptions on N transformations in ground water and the fate of atmospheric N deposition on
land, but all three result in substantially similar estimates of total N loading to the estuary (Cadmus,
1995). A fourth model (Sham et al., 1995) takes into account the time required for nutrient-laden
groundwater to travel to surface waters, where it can contribute to eutrophication. Newly
constructed septic systems and discharges may not, contribute to nutrient loading for several.
decades, depending on the hydraulic travel time from the source to a surface water body (Sham et
al., .1995). By analyzing construction dates of discharges and travel times, Sham and colleagues
estimated that current loading to Waquoit Bay is approximately 70 percent of the ultimate loading
from existing structures, and that 90 percent of the ultimate loading is reached in approximately 10
years (Sham etal., 1995). ,
DRAFTJune 13, 1996 43
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The analysis here will take into account ground water travel time, as elucidated by Sham etal. The
analysis used the CCC model as its base and also required a complete land parcel database for the .
Waquoit watershed, with date of construction for each parcel, as well as estimation of ground water
flow velocities from the extensive well data in the Waquoit watershed. A similar analysis at the
same level of detail for all watersheds in the model would be prohibitive. Such a level of detail is
probably unnecessary because the three base models jfor N loading have an estimated uncertainty of
25 to 40 percent (M. Geist, personal communication). Given the uncertainty of the base models, it
should be possible to develop coarser estimates of travel time and construction date and still be
within the uncertainty limits of the base model. .
Given the prediction that 90 percent of ultimate nitrogen loading is reached in 10 years (Sham et -
al., 1995), travel time can be approximated by estimating areas representing travel, times of 0 to 5
years, 5 to 10 years, and greater than 10 years. On a map, these would appear as concentric bands .
around an estuary or parallel to a stream. A first-order approximation would be to estimate the
distance traveled by ground water in 5 years (approximately 1 km in Sham et al., 1995) and apply
that distance to all watersheds in the analysis. Land use and dates of construction can be estimated
for each of the three travel bands from a GIS database, and one of the N loading models can then
be applied to estimate total N from each of the three source areas.
Cape Cod Estuary characterization. Approximately 90 semi-enclosed estuaries and subestuaries
are on the south shore of Cape Cod and the islands with a relatively narrow outlet to the sea or to
another estuary. Some will prove to be inappropriate for a regional model (e.g., too small, too
isolated, too open), but approximately .50 estuaries, might be sufficient for development of a
regional model. Eelgrass cover has been digitized from the Massachusetts DEP aerial images and
integrated into the GIS database for all of these estuaries (Figure 8).
Characterization of each estuary and subestuary will require assembly of a GIS database for Cape
Cod and the islands. The existing Mass GIS database will provide boundaries, coastlines, streams,
place names, land use, and census data. The Cape Cod Commission, has delineated ground water
watersheds for the Cape. The principal activities here will be digitization of bathymetry from the
NOAA charts and characterization of each estuary and subestuary using GIS. Each estuary and
subestuary will be characterized as follows:
Biological (from Mass DEP aerial images):
Eelgrass cover (percent of total area, .percent of area < 4m deep)
> Observations of Ruppia, Codium, and algae in the estuary
Physical (from Mass GIS and NOAA charts bathymetry):
> area
* maximum depth
« > mean depth
44 Waquoit Boy Watershed Ecological Risk Assessment
-------
* inlet width
> inlet length ,
'''* inlet maximum depth ,
> inlet mean depth . ,
'> water body type outside of inlet (sound, 1° estuary, 2° estuary)
* Total channel length from estuary or subestuary to sound
Watershed and Land.Use:
> Watershed area (ground water). Ground water watersheds have been delineated for
Cape Cod estuaries by the Cape God Commission.
> Land use (total area hi each land use class)
> Population
* , Area, land use, and population within 5-year ground water travel time to tidal
waters
»' . Area, land use, and population within 5-to-10 year ground water travel tune to tidal
waters .
* Area, land use, and population greater than 10 year ground water travel time to
tidal waters ; . ' ,
>' Distribution of new construction (< 5 yr old, < 10 yrold) in a watershed
Eelgrass response model for Cape Cod Estuaries. Following characterization of each estuary, data
will be plotted to determine whether relationships can be detected from scatterplots. The
scatterplots will help determine the most appropriate model: linear, curvilinear, or categorical
approaches such as logistic or loglinear models. At least four alternative models will be examined:
models using land use directly as a predictive variable, models using estimated nitrogen loading as
the predictive variable, and models with and without an estuarine retention time parameter.
Model 1 (simple land use)
y = a + bx, + -cx2 + 'dx3 + e , where
y = eelgrass cover .
x, = dwellings per unit estuarine surface area in the 0-5 yr travel band
x2 = dwellings hi the 5-10 yr travel.band .
. x3 = dwellings in the > 10 yr travel band.
DRAFTJune 13, 1996
45
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46
Waquoit Bay. Watershed Ecological Risk Assessment
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Model 2 (estimated N loading)
y = a + bx + e , where . .
x = areal nitrogen loading estimated from one of the N loading, models, taking into account
the three ground water travel bands and estimated proportion of new construction in each.
Models 3 and 4
Models 1 and 2 might be improved with an estuarine retention time parameter, the
Vollenweider parameter (Reynolds, 1984; Costa et al., 1995), but this requires more study:
-
V = twz-' (1 + ^J-', where ' ..
tw = average hydraulic retention time
z ' mean depth
so: y = V(a + bx + e) . .
y = v(a + bx, .+ Cxz + dx3 + e)
Retention time is difficult to estimate in estuaries because of highly variable .wind-induced and tidal
mixing during a tidal cycle (Geyer and Signell, 1994). Retention time can be bounded at the upper
limit by freshwater inflow assuming no tidal exchange (treating the estuary as a lake), and at the
lower limit by freshwater inflow, plus tidal inflow assuming complete mixing every tidal cycle.
Actual mean retention time will be somewhere between these two extremes. A first-order
approximation for these small estuaries will be to assume 50 percent mixing every tidal cycle, and.
calculate retention time accordingly. Alternatively, it has been suggested that macroalgae, because
they are held fast to one spot, intercept nutrients that are carried past them in water currents and
hence are not affected by- estuarine retention time. If retention time is unimportant, then the
retention time models will perform poorly relative to models 1 and 2.
Uncertainties associated with the eelgrass response model. An objective of risk assessment is to
characterize uncertainty and its sources that may play a role in prediction of risk. Sources of
uncertainty in the ecological risk assessment include:
* Alternative hypotheses. Other explanations or interactions operating that were not
addressed or that might impede attainment of management goals might be
operating.
* Model uncertainty. In the case of. the estuarine analysis, there are three
competing nitrogen loading models, each of which will be examined for a "best fit"
to the eelgrass response data. The resultant "best fit" model is empirical and does
not necessarily reflect underlying mechanisms; it seeks only the best fit to the data.
However, as long as the predictions of the best fit model hold, it is sufficient for
management.
r Data uncertainty. Data uncertainty includes data collection methods, adequacy of
sample size, random sampling error, and measurement error. Random error
(including natural variability) is part of the data distribution and can be analyzed
with empirical or Monte Carlo methods.
DRAFTJune 13, 1996 '. 47
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Uncertainties associated with factors affecting eelgrass. Predictions from the estuarine portion of
the risk assessment will include risk of 'continued eelgrass habitat loss, or, conversely, probability ' .
of eelgrass habitat recovery for given nutrient management scenarios. These predictions and
probabilities will derive from the empirical models developed hi the analysis phase on eelgrass
response to predicted nutrient loading. The response model will not cover several alternative and
interacting hypotheses that may also contribute to eelgrass loss or may prevent eelgrass habitat
recovery,. Thus, the models are intended to predict necessary., but not necessarily sufficient,
conditions for eelgrass recovery.
Eelgrass requires relatively clear water (Secchi depth = 1-2 m); it will grow in salinities greater
than 10-15 ppt, and sediments composed of fine sands or muddy sands (Batiuk et.al. 1992).
Necessary and sufficient conditions for eelgrass growth and recovery hi Waquoit Bay are:
* Low nitrogen concentrations that are not toxic to eelgrass ( < 1 ^M; Burkholder,
1992) and that permit eelgrass growth while limiting rapid growth of Cladophora
and Gracilaria. Cladophora is characteristic of eutrophic habitats. In Sage Lot
Pond, a subestuary of Waquoit Bay, Cladophora and Gracilaria were limited when
nitrate concentration was less than 1 yuM hi the water column and when sediment
interstitial ammonia was less than 1.5 fjM (Peckol et al., 1994). Similarly, Batiuk
et al. (1992) recommended nitrogen concentrations less than 0.15 mg/L DIN (<2.4
to limit phytoplankton growth in eelgrass habitat of the Chesapeake Bay.
Achieving low nitrogen loading to Waquoit Bay will require some sort of nitrogen
source control, as well as a sufficient lag time to allow nitrogen currently hi the
ground water to be flushed out. Groundwater travel times, in the watershed might
be several tens of years, depending on distance from a source to a water body
(Sham et al., 1995). Management scenarios to be analyzed will include an estimate
of the lag tune necessary for changes hi nutrient supply to take effect in the estuary.
A secondary tune lag is the pool of nitrogen hi the decomposing organic matter,
which is thought to be approximately 3 years' supply (Tampa Bay NEP, 1995).
The organic nitrogen pool may therefore require 3 to 5 years to equilibrate to a
lower level, but this appears to be negligible compared to the time lag hi the supply
rate. .
Absence of macroalgal and epiphytic growth capable of overgrowing and shading
eelgrass. Eutrophication and excess algal production are reversible if nutrient
availability is reduced. . Achievement of low nitrogen loading and a reduced
nitrogen pool hi the estuary will result hi reduced algal growth.
Low turbidity and low resuspension of fine organic matter. Because of the sandy ,
soils of Cape Cod, mineral turbidity (silt and clay) is not a problem hi Cape Cod
waters. In Waquoit Bay, fine organic matter from decomposing algae is
resuspended by wind, tide, and boat wakes. This organic matter can settle, on
eelgrass leaves, enhanced by the surface roughness of epiphytic algae. The
epiphytes and the organic sediment shade the leaves and can inhibit eelgrass
growth. Although this mechanism of sediment entrapment by epiphytes has been
proposed to contribute to SAV loss (e.g., Kemp et al., 1983; Short 1993), it has
never been demonstrated to operate hi the field or hi the laboratory.
48 Waquoit Bay Watershed Ecological Risk Assessment
-------
Excess organic matter is a consequence of excess production due to nutrient '
enrichment. If the supply of organic matter is reduced, by reducing nutrient -
loading and primary production, then,the organic matter pool would eventually
. * decline due to decomposition, burial in the sediment, or export from the system.
Thus, as long as nutrient loading is reduced, organic matter will decline with it,
perhaps delayed by a time lag of 3 to 5 years (Tampa Bay NEP 1995).
> Appropriate sediment for eelgrass growth. Eelgrass can grow in a variety of
sediments, including mixtures of sand and mud, fine sands, and other particle sizes
(Orth and Montfrans, 1984; Batiuk et al., 1992; Burkholder et al., 1992). The
sediment has previously been appropriate for eelgrass growth.
Appropriate salinity for eelgrass growth (> 10-15 ppt). Available information
indicates that Waquoit Bay has not freshened.
'."'»> Eelgrass propagules. Existing eelgrass- root stocks and seed banks might' have been
exhausted in the years of decline." Natural recolonization is a random event and
depends on nearby seed sources. The remnant eelgrass populations in the
subestuaries Hamblin and Jehu Ponds, as well as offshore populations, may provide
seeds to Waquoit Bay, but there is no way of knowing When such colqnization
might occur. Aerial images (1994) show large and extensive eelgrass beds hi
Vineyard Sound just outside the Waquoit Bay inlet (Figure 8). Alternatively,
eelgrass may be planted to restore meadows, if habitat requirements have been met.
. . Restoration (planting) of habitat that meets eelgrass ecological requirements (light,
, salinity, substrate) has met with mixed success (up to 80 percent survival but
variable; Batiuk etal., 1992). ,
Model uncertainty. The exposure-response models result in an empirical uncertainty, expressed as
the confidence intervals of the models. Another type of uncertainty is model uncertainty, or
indeterminacy, because it is not known which loading models are correct, or even which one gives
the best estimates of nitrogen loading and its sources. In the risk assessment framework, the
confidence intervals of the eelgrass response models represent uncertainty of ecological effects, and
the indeterminacy of the loadings models represent uncertainty of exposure.
Data Uncertainty. The standard error of predicted values is the uncertainty of the
exposure-response model. The exposure model, in turn, has uncertainty due to uncertainty of its
input variables. The output uncertainty can be simulated with a Monte Carlo approach and yields a
distribution of the output variable, N loading. The Nrloading distribution is then combined with
distributions of other input variables to the exposure-response model and the uncertainty of the
prediction to yield an overall uncertainty of the combined model. The uncertainty can be expressed
as a confidence interval or a cumulative distribution. .
The final models and then- estimated uncertainties can be used to predict the probable consequences
of specific management scenarios (e.g., effects of complete planned buildout; effects of sewer
installation hi selected portions of the watershed, effects of improved septic systems, effects of lawn
fertilizer ban). They can also be used to estimate the probability that a management action will fail
to achieve its target, and thus, how much effort is necessary to obtain, for example, 90 percent
probability of achieving the objective. , :
2.4.3 Future Nitrogen Loading to Waquoit Bay
DRAFTJune 13, 1996 49
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The CCC, BBP, and LMR models are steady-state models; however, Sham et al. (1995)
demonstrated that nutrient loading to the estuary is not in equilibrium with land use. Nutrient
loading and associated ecological effects can lag many years behind changes in land use as a result
of the time it takes for ground water to travel from the point of recharge to the estuary;
furthermore, the duration of the time lag varies across the watershed. Ground water travel times
from some parts of the watershed to the estuary may approach 100 years (Sham et al., 1995). For
, these reasons, nitrogen loading to the estuary is not a function of land use at any one point in time.
Empirical assessment of the relationship between land use and nutrient loading in Waquoit Bay
must take into account the time lag between contamination of ground water at the point of recharge
and discharge to the estuary. This can be most effectively accomplished by combining the major
elements of the LMER model at the Sham et al. model. A hybrid model should include the variety
of sources and loss terms incorporated into the LMER model, as well as the spatio-temporal aspects
of the Sham et' al. model. Indicators of nitrogen sources will need to be carefully chosen based on
availability of historical data. A critical factor to include from, the LMER model is attenuation of
nitrogen in ground water. ,
The goal of the hybrid modeling effort will be to produce a time-series of hindcasted and forecasted
nitrogen loading rates to Waquoit Bay that incorporates all of the significant sources for which
reliable data can be obtained. The form of the model output will be similar to that from Sham et al.
(1995). Nitrogen loading rates can then be plotted against measures of ecological effects. These
data can be used to aid interpretation of the ongoing, empirical, cross-sectional analysis of current
land use and eelgrass extent in Cape'Cod estuaries.
The predicted time series of nitrogen loading to Waquoit and observed eelgrass cover can be used
to test the regional model developed above. Following testing, the models can be used to predict
the effects of different nutrient management scenarios for Waquoit bay.
2.4.4 Potential Future Analysis for Other Stressors
The preliminary comparative risk analysis identified nutrient loading as the dominant stressor in the
watershed. This risk assessment will explicitly analyze estuarine nutrient loading, leaving
freshwater nutrient loading, habitat alteration, and other stressors for future, more comprehensive
analysis. Directions this future analysis could take are discussed below.
Pond Nutrient Loading. Ashumet and Johns Ponds are subject to nutrient enrichment (primarily
phosphorus) from ground water and nonpoint runoff.
Objectives
> Characterize expected trophic state of Cape Cod ponds not subject to discharges,
residential septic seepage, and suburban lawn and road runoff.
> Characterize current trophic state of Ashumet and Johns ponds from ongoing MMR
studies.
> Estimate risk of further eutrophication of the ponds based on projected increases in
P loading, using a Vollenweider eutrophication model.
50 Waquoit Bay Watershed Ecological Risk Assessment
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Physical Habitat Alteration. Physical habitat alteration has the greatest, potential effects on
freshwater stream components and on water dependent wildlife. Effects are well-known: removal
of a habitat results in removal of species dependent on that habitat. It is generally not reversible
unless the original habitat is restored. Physical habitat alteration in the Waquoit watershed includes
beach protection, which changes the dynamics of barrier beaches; road and subdivision
construction in nontidal wetlands; and road and development alterations of streams. Except for
beach protection, the continuing extent of habitat alteration in the Waquoit watershed is poorly
known. Salt marsh is currently protected from further encroachment by development; freshwater
wetlands, less so. Habitat of the Quashnet River has been restored, but not in the Childs River. It
is not known whether further habitat alteration will take place in these rivers.
A second component is temporary habitat disruption, with no permanent habitat loss. If the
disruption is more frequent and more severe than the ability of the system to recover, it can become
a permanent loss. Disruption is often a question of overuse, such as by mountain bikes, off-road
vehicles, or boats. The principal concern in Waquoit has been boat propellers clipping eelgrass and
preventing its recovery. ,
Objectives
> Measure the present and historical extent of suitable habitat for beach and dune
nesting birds.
» Quantify the abundance of plovers and terns in the watershed.
* . Correlate habitat and bird abundance data.
Development of habitat loss-response relationship between avion habitat and species abundances.
Habitat loss is well known to cause irreversible loss of species dependent on the habitat for a key
part of their life cycle. Birds are particularly vulnerable to loss of nesting areas, and fish are
vulnerable to loss or degradation of spawning areas. The U.S. Fish and Wildlife Service, the
National Biological Service, and the Massachusetts Audubon Society might have information on
suitable habitat for beach and dune nesting birds, estimates of past habitat extent, and bird counts or
nest counts in the area. If the information is available, it may be possible to determine trends in
available habitat and nesting activity over time and in relation to land use and population
measurement ehdpoints. ,
Eelgrass Disruption. A stress-response relationship between eelgrass and boating activity is more
difficult to develop because data are more difficult to obtain and because boating activity and
nutrient loading are likely to be collinear in the Cape Cod region. Information from sites with high
boating activity but low nutrient loading, and sites with high nutrient loading but low boating
activity will be needed. Sargent et ai. (1995) documents seagrass scarring from propellers at sites
around the coast of Florida. .
Alternatively, what information would be required to answer this hi the future? A simple
experiment would be to cordon off several areas from boat traffic after nitrogen management is
implemented. Eelgrass regeneration within the fenced areas but not outside would indicate that
boat traffic is significant in inhibiting eelgrass regrbwth.
Other Stressors. All other stressors identified in this risk assessment ranked lower in priority in the
comparative risk analysis. The MMR toxics assessment will analyze human health risks due to
, DRAFTJune 13, 1996. . " 51
-------
toxic substances in the ponds, and an ecological risk analysis is still needed. For the other
stressors, too few data exist for further analysis at this time. Possible hypotheses that would be
addressed in later phases of this risk assessment include:
» Altered riverine flow. Altered flow in the streams from ground water removal,
cranberry cultivation, and storm water runoff decrease stream base flow and
increases stormflow, and increase the risk of habitat degradation for anadromous
fish and invertebrates in the streams of the watershed.
> Toxic chemicals. Toxic chemicals in ground water plumes and from lawn and
suburban stormwater runoff increase the risk of loss of freshwater and estuarine
fish and invertebrates. ,
> Harvest pressure. Excessive harvest pressure increases the risk of loss of
commercial and recreational fish and shellfish in the estuarine and freshwater
systems of the Waquoit Bay'watershed.
> Suspended sediments. Suspended sediments, primarily from resuspension of
organic floe by boat wakes hi the estuary, increases the risk of loss of eelgrass due
to sedimentation of the floe on the eelgrass blades and increased light attenuation;
and therefore also increases the risk of loss of estuarine fish and invertebrate
habitat. .
A future analysis approach would be to assess the extent and magnitude of each of the stressors, to
address the question of exposure of the system to the stressors. For example, analysis of altered
flow might include determining the stormflow hydrography of the most altered stream (Child's
River), and" comparing it to less altered streams such as the Quashnet or other rivers. Alteration of
base flow could be addressed by analysis of USGS gauge readings. USGS might have determined
stormflow hydrographs for streams with a gauging station. If flow alteration is minor, even in the
most heavily altered stream, flow alteration is a negligible problem overall. ,
52
Waquoit Bay Watershed Ecological Risk Assessment
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Waquoit Bay Watershed Citizen Action Committee, Waquoit, MA.
WBNERR. 1989. Management plan. Waquoit Bay National Estuarine Research Reserve,
National Oceanic and Atmospheric Administration and Massachusetts Department of
Environmental Management, Waquoit, MA.
WBNERR. 1993. Waquoit Bay research report 1992-1993. Waquoit Bay National Estuarine.
Research Reserve, National Oceanic and Atmospheric Administration and Massachusetts
Department of Environmental Management, Waquoit, MA.
WBNERR. 1995. Waquoit Bay research report 1994-1995. Waquoit Bay National Estuarine
Research Reserve, National Oceanic and Atmospheric Administration and Massachusetts
Department of Environmental Management, Waquoit, MA. .
Weiner, J.G. 1995. Bioaccumulation of mercury in fish. In National Forum on Mercury in fish:
Proceedings, pp. 41-47. EPA 823-R-95-002. U.S. Environmental Protection Agency, Office of
Water, Washington, DC.
Welsh, B.L., J,P. Herring, and L.M. Read. 1978. The effects of reduced wetlands arid storage
basins on the stability of a small Connecticut estuary. In Estuarine interactions, ed. M.L. Wiley,
pp. 381-401. Academic Press, New York,
Wright, S.B. 1987. An assessment of the biological and physical changes in the Quashnet River
caused by a stream rehabilitation project. Master's Thesis, Northeastern University, Boston, MA.
DRAFT-June-13, 1996 61
-------
Yingst, J.Y., and D.C. Rhoads. 197.8. Seafloor stability in Long Island Sound: Part II. Biological
interactions and their potential importance for seafloor credibility. In Estuarine interactions, ed.%
M.L. Wiley, pp. 245-260. Academic Press, New York.
Zimmerman, R. C., J. L. Reguzzoni,- S. Wyllie-Echeverria, M. Josselyn, and R. S. Alberte.
1991. Assessment of environmental suitability for growth oiZostera marina L. (eelgrass) in San
Francisco Bay. Aquat. Bot. 39:353-366.
APPENDIX A:
LIST OF PARTICIPANTS IN THE
WAQUOIT BAY WATERSHED CASE
STUDY
Waquoit Bay Risk Assessment Team
Suzanne Marcy
Parti Tyler
Maggie Geist
David Dow
Jeroen Gerritsen
Chuck Spooner
Conchi Rodriguez
Vicki Atwell
Technical Panel Chair, U.S. Environmental Protection Agency, Office of
Water
U.S. Environmental Protection Agency, Region 1
Waquoit Bay National Estuarine Research Reserve
National Marine Fisheries Service, Northeast Fisheries Science Center
Tetra Tech, Inc.
U.S; Environmental Protection Agency, Office of Water
U.S. Environmental Protection Agency, Office of Prevention, Pesticides
and Toxic Substances , ' _
U:S. Environmental Protection Agency, Office of Research and
Development
Waquoit Bay Risk Assessment Contributors
Edward Eichner Cape Cod Commission .
Joe Costa Buzzards Bay National Estuary Program
Ivan Valiela Boston University
Charles Costello Massachusetts Department of Environmental Protection
62
Waquoit Bay Watershed Ecological Risk Assessment
-------
Heidi Clarke Yale University
/ ' " - '
Tom Cambareri. Cape Cod Commission
Lynn Feldpausch U.S. Environmental Protection Agency, Region 1,
Jack Gentile U.S. Environmental Protection Agency, Office of Research and
Development
Chi-Ho Sham The Cadmus Group, Inc.
(. ' ' ' . .
APPENDIX B: NEWSPAPER ADVERTISEMENT AND
ARTICLE ON WAQUOIT BAY
WATERSHED CASE STUDY
DRAFTJune 13, 1996 .'. 63
-------
REVIEW.ORAFT - 10 May 1996 - DO" NOT CITE OR QUOTE
APPENDIX B
NEWSPAPER ADVERTISEMENT AND ARTICLE
ON WAQUOIT BAY WATERSHEDCASE STUDY
The US Environmental Protection Agency (EPA), » conjunction with the
Waquoit Bay National Estuarine Research Reserve (WBNERR)
ii prowl to announce thtt the Waquoit Bay Bftuaxy watershed if one of five lelected nationwide
for participation in an ecological risk assessment oue study beginning this fall.
The framework developed for ecological riik assessment is bated on fhe Human Health Risk
Assessment format employed successfully by the EPA for the last tea yean. ThJi prooew it
designed to identify and evaluate human health "stressors" in a variety of settings and provide
this information to those ptraons effected. A human health strHsor is defined as any physical,
chemical, or biological entity that can induce an adverse effect on the human organism.
Examples of such stressors range from highly toxic substances such as plutonium to less harmful
considerations such as ultraviolet solar radiation.
A similar approach is now being applied to whole watersheds. Here, the "ecological health" of
the watershed ecosystems is the prime consideration rather than the physical health of human
individual. The Waquoit Bay watershed hat been selected as the representative of marine
coastal embeyments in the case study which begins this fall. Other watersheds which have also
been selected include: the Clinch-Powell River in Tennessee, the North Plane River in Nebraska,
the Snake River in Idaho and the dig Darby Craft in Ohio.
To initiate resident involvement in this project EPA and WBNBRR are holding a:
Public Forum » September 21st - 7 PM
Waquoit Bay Yacht Club.
The purpose of this meeting is to receive input from all on what ahould be considered a* en
"ecosystem stressor" in this watershed. An example of one ecological sveisor already under
scientific investigation at Waquoit Bay is nutrient nitrogen (nitrate). This substance is not a
significant human health stressor but, because of its effect on the growth and spread of certain
marine algas, it has had a major effect on the structure of the Bay's benthic ecosystem.
We invite all persons to attend with their concerns and ideas. This meeting is expressly for fhe
purpose of receiving public input befort prioritizing and evaluating the ecologie risk factors at
Waquoit Bay. Waquoit Bay watershed residents are those with the historical perspective and
your input ii a highly-valued pan of the process, Be assured that all input will be recorded and
carefully considered by the project personnel. ,
The Wsquoit Bay Yacht Club is located on Seapit Readjust off Rtc. 28 near the Child* River
crowing/This is just across the river from Edward's Boatyard. If you have any questions about
this mooting or, if you have input but are unable to attend, please contact Dr. R. Jude
Wilbcr, Educational Coordinator at WBNERR, 508-457-0495.
-------
Serving The Upper Cape Since 1895
Tuesday, September 28,1993
, Page Three
Risk Sludy Will Be Used To Develop
Guidelines To Protect Waquoit Bay
VI* *r. i K^n A B_ : !w j m . ' *^
By {CATHERINE M. LUSSIER
The Environmental Protection
Agency is performing a risk as-
sessment-rate -ifaufrrnm friB It
quoit Bay Estuary that will iden-
tify human activities that cause
adverse biological, chemical
and/or physical effects and will
develop guidelines on how-to pro-
tect the watershed.
About 20 residents met at the
Waquoit Bay Yacht Club Tuesday
night with officials from the EPA
and the Waquoit Bay National Es-
tuarine Research Reserve to offer
suggestions on what activities neg-
atively affect the watershed and
what resources and values resi-
dents want to preserve. The as-
sessment team will also meet with
researchers from the research re-
serve for input.
"We have the experience in do-
ing risk assessments," Pattl Tyler,
chairman of the Waquoit Bay w»
has used th^ process success-
filly lor the past »io years for the Hu-
.W&SSiSkZatok Assessment but has
not used It to study ecological risks.
tenbed risk assessment work
-group said, "-but we do not have
knowledge of the watershed."
She added that the group was
seeking comment from the public
because it knows what activities
are happening in Waquoit Bay
and what resources have been
damaged.
Resident! identified about 50
stressors activities that nega
tiveJy affect an ecosystem that
they wanted the work group to in-
vestigate. Some of these stresson
included nutrient loading, shell-
fishing by raking or plunging.
building and development, boat
speeding, acid rain, and paint and
oil on boat bottoms.
In addition, they listed about 23
resources and values they would
like to see preserved at Waquoit
Bay, including wildlife, habitat,
shellfish, finflsh, clean water
open space, visual beauty and '
recreational atmosphere.
Suzanne Larcey. chairman of
the technical committee oversee-
ing the five Ecological Risk As-
sessment case studies that will be
conducted in the nation, said that
this study will be the first that ex-
amines the combined effects of a
chemical; physical and biological
stresson on an ecological system.
"A process is needed to assess
multiple stresson," Dr. Lercey
While many researches have
conducted studies on Waquoit
Bay, the director. Christine Oault
said, they have focused on one is-
sue or one stressor. "
' "One of the benefits of toili pro-
ject Is that it's going to pull to-
gether all of the results'6f these'
projects." she saidV-T'.'r,
The study will- test .a risk :as-
sessment process-that evaluates
and ranks the potential threat of
activities on ecological resources
nd determines how people can
protect .resources from those
threats. The EPA has used the
i prows successfully for the past
m £?iWVor- ftVSuWfn Health
I Risk Assessment, but has not used
it to study ecologfoataUks. -u
"We need to find a way of pull-
ing r all a of 'that v information-'to-
getherin a cohesive manner." Or
--
River in Tennessee, the MlddU
Platte Wetlands in Nebraska, the
Snake River in Idaho, and the Big
Darby Creek in Ohio.
A Unique Watershed
In June, the .EPA selected Wa-
quoit Bay as a case study because
the estuary is a unique watershed
with discrete and identifiable
stressors and a large amount local
and scientific interest The work
group conducting the study will
not gather new data, but will use
existing data from former pro-
jects.
The work group comprises five
officials from the EPA and R.
Jude Wilbur, educational coordi-
nator at the reserve.
. By November, the group plans
to complete the first phase of the
process, which is to identify the
problems it will examine and
what impacts it expects to see,
"This tells us where we need to
go," Dr. Larcey said.
The group will then gather and
analyse available information on
Waquolt Bay. Ma. Tyler said that
members have already talked
with scientists from the Woods
Hole Oceanographic Institution
Boston University and Smith Col-
lege, who have conducted re-
search on Waquoit Bay.
The last stage of the process is
to characterize the risks. Dr
Larcey expects that the group will
complete the draft of the risk as-
sessment by next September.
In addition, the group will use
the case studies to develop guide-
lines that will advise residents
and researchers on how they can
use the study's information effec-
tively and can protect the estu-
ary's resources. Dr. Larcey said
hat the guidelines will not only
be developed for the specific case
studies, but can be used for any
watershed.
Two offices of the EPA are
sponsoring the study. The Risk As-
essment Forum wants to test the
risk assessment framework for an
icoiogical study and wants to use
he information to develop risk as-
easment guidelines. The Office of
Water wants to use the informa-
on for watershed planning.
In addition to Waouoit RJIU
-------
-------
APPENDIX C:
RESULTS OF THE WAQUOIT BAY
PUBLIC MEETING
A public forum was held September 21, 1993 at the Waqouit Bay Yacht Club. Participants
contributed to the identification of what was valuable in the watershed (Table C-l.) and to the
identification of the principal stressors that might be placing those valuable resources at risk (Tables
C-2 and C-3). .
Table C-l. Environmental values/concerns that should be protected in the Waquoit Bay watershed.
Environmental Values/Concerns That Should Be Protected
Open Space
Non-Economic Values . - ' -
Historical/Political Perspective
Traditional Lifestyles
Scenic Views
Education
Indigenous Wildlife
Flyway Integrity
(migrating waterfowl)
Recreation ,
(swimming)
Food Resource Safety
Tourists .;".'
"Historical" Bay Ecosystem Structure ,
"Quality of Life"
(pleasant sensual experiences, natural noise,
smells, sights, night sky/darkness, freedom
to enjoy, visual beauty, access to natural
beauty, wildlife, vegetation, pheasants,
skunks, clean water, clean air)
Shellfishery
Shellfishing
"Clean" Water
Shoreline
Human Serenity
Marshland
Upland-Marsh Ecotone
"Habitat"
Recreational "Atmosphere"
Water Quality
Flushing Rates
Air Quality .
Questions on General "Health" of Existing
Ecosystem(s)-Health AS Measured, (re: only
identified "active" stressor)
Washburn Island
Human Health and Domestic Animals Health
(re: lyme disease)
Habitat .
Striped Bass
Navigation
Ground Water Quality
Eel Grass
Wildlife
Marine Organisms
Finfishery .
Finfishing
Herring
Aquifer Integrity
(flow rates) . ' . '
64
Waquoit Bay Watershed Ecological Risk Assessment
-------
Table C-2. Tj-pes of stressors affecting the Waquoit Bay watershed.
,, Stressor
Dredging
Commercial Overfishing Outside of the Bay '
Commercial Trawling
Water Withdrawal & Effect of Groundwater/Surface Water Relationship
Non-Native Species
Bacterial Population
Acid Rain
Ignorance, Lack of Education
Nutrient Loading
Fertilizers for Lawn, Golf Courses and Agriculture; Sewage Treatment
Plants; Acid Rain; Road Runoff; Boats; Livestock & Pets; Wildlife
(Waterfowl)
Boat Prop Disturbance
Shellfishing
Raking; Plunging
Waterfowl
Boat Wake Disturbance '
Overpopluation
Uncontrolled Growth, Uncontrolled Access
Habitat Loss
Loss of Ecotone Between Marsh and Upland; Trampling of Marsh by
Boats and People; Unmonitored Campling; Upland Development
Resulting in Sedimentation and Hydrologic Changes
Lack of Values
Non-Nutrient Runoff
Man-Made Noise
Historic Fuel Dumping ' .
Residual Contamination within the Atmosphere
Wet Deposition
Dry Deposition
Regional Air Transport and Patterns
Ignorant Tourists .
Apathy
Fertilizers
Insecticides, Pesticides
Global Warming
Chemical
X
X
X
X
X
X
X
X
X
X
Physical
X
X
X
X
X
X
X
X
X
X
/ »
X
X
'
X
Biological
X
X
X
X
X
X
X
X
X
, x
'
X
X
DRAFTJune 13, 1996
65
-------
Table C-2. Types of stressors affecting the Waquoit Bay watershed (continued).
' ' :.'. Stressor "."' '"".'. ':, -.' ' ':"- ...
Sea Level Rise ^
Catastrophic Storms
Nor 'Easter, Hurricanes
Boating Impacts from Shade and Anchorage
Docks and Piers ,
Boat Bottom Paint, .Oil and Fuel .
Boat Speeding .
Shoaling > Loss of Flushing within Bay
Building/Development
Careless Disposal of Chemicals
Uncontrolled Drainage
Road Runoff, Agricultural
Lead Shot
Cresote on Pilings
Copper Arsemate on Pilings
Underground Storage Tanks ' .
Lyme Disease ' " ,
Ticks, Deer, White-Footed Mouse (Vectors)
Lack of Management
Short-Term Economic Values
Otis Air Force Base
.Willful Destruction of Natural Resources '.' .
Lack of Enforcement
Chemical
X
X
x
X
x
X
X
X
X
X
X
Physical ,
X
X
X
X
X
X
X
X
X
X
X
X
Biological
X
X
X
. 'X ''<
X .
X
X
x ,
66
Waquoit Bay Watershed Ecological Risk Assessment
-------
Table C-3. Waquoit Bay watershed stressors and ecological effects.
Source
Septic systems,
fertilizers,
atmospheric deposition
Septic systems
Septic systems
Nutrient input
Nutrient input
Nutrient input
Nutrient input
Macroalgal growth
MacroaJgal growth
Macroalgal growth
Unleashed dogs, gulls,
crows, red fox, and
eastern coyote
Mute swan
Fertilizers and septic
systems
Stressor .
Nitrogen
Pathogens
Fecal coliforms
Shading by
macroalgae
Shading by
macroalgae
Increase in macroalgal
growth
Increase in macroalgal
growth
Increased respiration
of macroalgae
Increased respiration
of macroalgae .
Competition by
macroalgae
Wild predators
Introduction of exotic
species
Phosphorus
Type. .
Chemical
Biological
Biological
Physical
Biological *
Biological
Physical
Chemical
Biological '
Biological
Physical and
biological
Biological
Chemical
Ecological Effects
Increase in macroalgae and
phytoplankton growth
Introduction of pathogens and fecal
coliforms to surface water
Shellfish bed closures
Alteration of substrate and decrease in
light attenuation
Major faunal alterations in benthic and
fish communities
Alteration of macroalgal species
composition
Loss of habitat for submerged aquatic
vegetation
Loss of spawning sites for fish
Loss of hiding places and protection of
fish
Loss of scallop larvae settling habitat
Change in water coloration
Decrease of dissolved oxygen within the
water, column.
An increase in respiration rates in
combination with a temperature and
cloud cover increase =anoxic events
Mortality within benthic invertebrate
and fish populations
Loss of eelgrass habitat
Disturbing nesting areas for two
endangered species piping plover and
least tern and the threatened roseate tern
Displacing native waterfowl species
DRAFT-June 13, 1996
67
-------
Table C-3. Waquoit Bay watershed stressors and ecological effects (continued).
1 . ' ' ' 'Source';: -.-, ;;':> .
Marinas and piers
Gasoline, motor oil,
Automobile and boat
engines
Massachusetts' Military
Reservation
(Otis Air Force Base)
Massachusetts Military
Reservation
(Otis Air Force Base)
Lawns, golf courses,
cranberry bogs
Road deicing salt .
Landfill leachates
?
e.
;:\-H;;stressor.;.-.;,.. -':/
Antifouling chemical
leachate
Organic compounds
acetone, benzene,
naphthalene,
petroleum
hydrocarbons,
polychlorinated
biphenyls and creosote
*Methylene chloride,
cis 1,2 dichlorbethy-
lene, 1,1,1-
trichloroethane, ,
trichloroethy-lene,
perchloro-
ethane, 1,2-DBA,
toluene, ethylbenzene,
xylene in Sergou
Phase I Field GC
Screening Data
DCE, ICE, PCE, in
Ashumet Valley
Groundwater Plume
Need information
Need information
Unrecorded dump
sites (need more
information)
Metals-
arsenic, cadmium,
chromium, copper,
lead, mercury,
molybdenum, nickel,
silver, zinc
Hurricanes or severe
storms
.:.', '...Type-. .
Chemical
Chemical
Chemical
Chemical
Chemical
Chemical
Chemical
Chemical
Physical
' Ecological Effects. .'....'.'
Negative biological effects on organisms
in contact with it
?
?
?N
?
Phytotoxicity, leaf fell
? '
Looking into obtainitag information
from the EMAP program "
Flooding of upper estuary
Shoreline erosion
Altered tidal regime
Increase volume of water input
Sediment resuspension
68
Waquoit Bay Watershed Ecological Risk Assessment
-------
Table C-3. Waquoit Bay watershed stressors and ecological effects (continued).
Source
"*
Commercial shellfishing
Construction development
Otis Air Force Base
Global climate change
Stressor
Seawalls and jetties
Boat propellers
Polar outbreaks .
Raking and plunging
for scallops
Filling wetlands
Thermonuclear
explosion
Sea level rise and
increase in turbidity
and sediment loading
Dredging channels.
. Type
Physical
Physical
Physical
Physical
Physical
Physical
Physical
Physical
. , Ecological Effects
Major alteration of shoreline dynamics
Sediment resuspension
Coastal erosion
Sediment buildup
Change in flushing rates
Rip-up vegetation
Sediment resuspension
Increased turbulence and mixing in
water column
Freezing of bay
Disturbing sediment
Resuspending nutrients
Increasing turbidity
Loss of marsh-uplands ecotone
Increase surface water runoff (activities
such as paving to lead to an increase in
. surface water runoff temperature)
Increase sediment loading
Alter groundwater flow
Intense heat and the end of life as we
know it
Flooding
Alteration on coastline
Increase in turbidity and sediment*
loading
Sediment disturbance and increase in
turbidity
DRAFTJune 13, 1996
69
-------
APPENDIX D:
WAQUOIT BAY MANAGEMENT
GOALS MEETING
Attendees
, Tom Cambareri
Bruce Carlisle
Joe Costa
David Dow
Perry Ellis
TomFudala ,
Jeroen Gerritseh
Steve Hurley
Chuck Lawrence
Sandy McLean
CarlMelberg
Jo Ann Muramoto
MarkPatton
Pam Polloni
Bob Sherman
Jan Smith
Patti Tyler
Mary Varteresian
Brooks Wood
Rick York
Cape Cod Commission
Massachusetts Coastal Zone Management
Buzzards Bay National Estuary Program
National Marine Fisheries Service, Northeast Fisheries Science Center
Mashpee Harbor Master .
Mashpee Planning Department
Tetra Tech, Inc.
Massachusetts Division of Fisheries and Wildlife ,
Cape Cod Commission -
Citizens for the Protection of Waquoit Bay
U.S. Fish and Wildlife Service
Fahnouth Conservation Commission
Otis Installation Restoration Program
League of Women Voters, Falmouth
Mashpee Conservation Commission
Massachusetts Coastal Zone Management .
U.S. Environmental Protection Agency, Region 1
U.S. Fish and Wildlife Service
Monomoscoy Improvement Trust
Mashpee Shellfish Department
70
. 'Waquoit Bay Watershed Ecological Risk Assessment
-------
Waquoit Bay Concerned Organizations
Ashumet - John's Pond Association
Ashumet Valley Property Owner's Association, Inc.
Association for the Preservation of Cape Cod
Atlantic States Marine Fisheries Commission
Barnstable County Department of Health and
Environment
Cape and Islands Coastal Waters Steering Committee
Cape and Islands Self Reliance Corporation
Cape Cod Beagle Club
Cape Cod Commission (CCC)
Cape God Cooperative Extension Service
Citizens for the Protection of Waquoit Bay
Davisville Association
F. A. C. E. S.
Falmouth Rod and Gun Club
Falmoum Condo Trust
Green Briar Nature Center
Mashpee Briarwood Association, Inc.
Massachusetts Audubon Society
Massachusetts Coastal Zone Management (CZM)
Massachusetts Department of Environmental
Management (MADEM)
Massachusetts Department of Environmental
Protection (MADEP)
Massachusetts Department of Fisheries, Wildlife,
and Environmental Law Enforcement
Massachusetts Heritage Society
Massachusetts Military Reservation (MMR)
Menauhant Harbor Association
I
National Oceanographic and Atmospheric
Administration (NOAA) National Estuarine Research
Reserve System (NERRS)
NOAA National Marine Fisheries Service. (NMFS)
National Science Foundation (NSF) Land Margin
Ecosystems Research (LMER)
The Nature Conservancy
Seacoast Shores Owners Association
Shorewood Beach,Owners
Sierra Club - Cape Code Group
South Cape Beach Advocates
The 300 Committee, Inc.. ,
Town of Falmouth
Town of Mashpee
Town of Sandwich
Trout Unlimited
U.S. Army Corps of Engineers (COE)
U,S. Department of Agriculture (USDA) Soil
Conservation Service (SCS)
U.S. Fish and Wildlife Service (USFWS)
U.S. Geological Survey
Wampanoag Tribal Council
*
Waquoit Bay National Estuarine Research Reserve
(WBNERR)
Waquoit Bay Watershed Citizens Action Committee
(formed of representatives of other groups)
Waquoit Bay Watershed Intermunicipal Committee
Waquoit Bay Yacht Club
DRAFTJune 13, 1996
71
-------
APPENDIX E: ASSESSMENT OF AVAILABLE
INFORMATION
A summary of the assessment of available information was provided in Section 2.1 of the Waquoit
Bay Problem Formulation. The following material describes in more detail the ecosystems at risk,
reviews ecological effects that have been observed in the watershed, and provides a preliminary
characterization of stressors in the Waquoit Bay watershed based on studies conducted in the
watershed and elsewhere.
E.I Characterization of the Ecosystems at Risk
The Waquoit Bay watershed covers approximately 53 square kilometers (21 square miles) and
spans parts of the towns of Falmouth,>Mashpee, and Sandwich on the south coast of Cape Cod,
Massachusetts. The watershed was first delineated by Babione (1990) and further refined by
Cambareri et al. (1992). Recent work by Brawley and Sham (in prep.) reinterpreted the watershed
delineation of Cambareri et al. (1992) to develop a three-dimensional model of the drainage basin.
The watershed covers 8 km (5 mi) from the head of the Bay to the regional ground water divide in
the vicinity of Snake Pond (Figure E-l). The Bay and its tributaries encompass a total surface
water area of 3.9 km2/389 ha (1.5 mi2). The major surface water components of the watershed
include the Waquoit estuary, two major rivers and several smaller streams, freshwater ponds, and
freshwater wetlands. Within the Waquoit Bay watershed are seven subwatersheds (Childs River,
Sage Lot Pond, Quashnet River, Eel Pond, Head of the Bay, Hamblin Pond, and Jehu Pond) and
four ponds (Ashumet, Johns, Snake, and Flat). .These subwatersheds provide diverse habitats that
support a variety of ecological communities, including barrier beaches along the Atlantic Ocean,
eelgrass beds, saltwater and freshwater marshes, erosion and accretion areas, coastal sand dunes,
brackish water ponds, fish spawning and nursery areas, and wildlife habitat.
E.I.I Watershed-wide Characteristics
The Waquoit Bay watershed lies entirely within the Mashpee pitted outwash plain (LeBlanc et al.,
1986), a geologically young landform composed of glacial materials deposited on top Of bedrock
toward the end of the Wisconsinian Glacial Stage, about 12,OOiO years before present (Oldale,
1992). Outwash plains were created by broad meltwater streams which size-sorted the drift
materials depositing the heavier, boulders and pebbles near the glacial margin and gravel and sands -
further away. Because Cape Cod is so young geologically, the glacial materials have not been
significantly altered, resulting in a generally sandy, porous soil throughout the area. In addition to
gravel and sand, there are clay and silt lenses; this finer grained material generally is found in
deeper sediments to the south.
' , f
The term "pitted "refers to the numerous kettle ponds dotting the landscape. Kettle ponds mark the
sites where blocks of ice were buried by sediment-laden meltwater streams beyond the glacial
margin. Johns Pond and Ashumet Pond .are two examples of kettle ponds in the watershed
(HAZWRAP, 1995). Waquoit Bay, itself, may have originated as a kettle pond. The southern
margin of the bay was flooded by sea-level rise at the close of the Wisconsinah Glacial Stage, when
the ice sheet retreated, inundating low lying coastal areas and raising the water table inland due tp
hydrostatic pressure at the saltwater-freshwater interface. The action of winds, waves and currents
continually, eroded and displaced the loose glacial sand and gravel contributing to the formation of
72 Waquoit Bay Watershed Ecological Risk Assessment
-------
coastal sand dunes, sea cliffs, barrier beaches and salt marshes. These processes continue to alter
the dynamic shore (Oldale, 1992). .
Waquoit Bay's geology controls the region's hydrology, which is typical of a glacial outwash plain.
The Bay, 1.2 km (4,000 ft) wide and 3.4 km (11,000 ft) long, is a shallow estuary, average depth
of 0.9 m (3 ft), fed by freshwater streams and ground water with tidal exchange to Vineyard Sound
through two dredged and maintained channels, and a recent breach caused by overwash. during
Hurricane Bob in August 1991 (Valiela et al., 1996). Fifty percent of the water entering Waquoit
Bay comes from the Quashnet and Childs Rivers, 23 percent from direct precipitation, and 27
percent from ground water recharge in the watershed. Ground water in the Cape Cod region is
generally formed by .precipitation. Ground water recharges the area, upgrade from the ponds and
discharges from the downgradient portions of the ponds (Cambareri et al., 1992). The rivers.
derive most of their water from ground water discharge, draining the shallow surface aquifer.
Ground water is forced to the surface as the permeable aquifer thins from north to south hi the
watershed. ' . ,'
The unconsolidated sediments of Cape Cod make ideal aquifers-underground areas that contain
enough water to supply significant amounts of water for community use. The permeable aquifer
ranges from about 46 m (150 feet) thick near Snake Pond, thinning to 9 m (30 feet) near Waquoit
Bay (Garabedian et al., 1991; Cambareri et al., 1992). The porous soils support rapid percolation
of rain, nutrients, and contaminants into the subsoil and eventually to the ground water. In
recognition of the unique ground water characteristics of Cape Cod, the U.S. Environmental
Protection Agency declared this region a Sole-Source Aquifer in 1982i a designation designed to
facilitate protection of the water supply. In actuality, the Cape Cod aquifer can be subdivided into
six ground water "lenses" or areas of elevated ground water; surface features, such as rivers,
separate the lenses and generally ground water does not flow between lenses. The Waquoit Bay
watershed lies within the Sagamore or western Cape lens of the Cape Cod Aquifer (Guswa and
LeBlanc, 1981). -
The watershed's hydrology and habitats are influenced by its climate, which is similar to that of
other areas in the northeastern United States but typically has milder winters and cooler summers
due to surrounding ocean waters. January and February are the coldest months and July and
August are the warmest months. Fog may be common in the spring and summer and humidity is
typically high in the summer. Annual precipitation is between 107 and 112 cm (42 and 44 inches),
ground water recharge is approximately 45 percent of the total precipitation.. Snowfall is variable
from one year to the next but is close to 76 cm (30 inches) per year. Between October and April
the prevailing winds are northwest whereas from May to September winds come from the
southwest. Hurricanes are most common in the late summer and early fall and "northeasters" may
occur in whiter and early spring.
The surface water ecosystems in the lowlands and uplands of the Waquoit Bay watershed contain
several critical habitats identified by the Association for the Preservation of Cape Cod (VanLuven,
1991), including coastal plain pond shores, anadromous fish runs, salt marshes, eelgrass, barrier
beaches, and woodlands. Habitats in the watershed are also affected by the southward-flowing cold
Gulf of Maine waters and the northward-flowing warm Gulf Stream, which mix off the coast of
Cape Cod to form a biological transition zone between the Virginian (temperate) and Acadian
(boreal) biogeographic provinces (Ayvazian et al., 1992). This overlap produces more diverse
communities than occur in either province. The Waquoit Bay watershed also,lies near the Atlantic
coast flyway, an important migratory corridor for many coastal and arctic-nesting birds,
particularly shorebirds, as well as .state and federally protected species. The flora of the watershed
DRAFTJune 13, 1996 , ' . 73
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include scrub oak and pitch pine forests (Bailey, 1995); forests covered 2650 ha (6548 acres) of the
watershed in 1990 (Appendix F). Among the state protected plant species found in the watershed-
are the sandplain gerardia, Agaliriis acuta (endangered); the bushy rockrose, Helianthuetnum
dumosum (threatened); the knotroot foxtail, Setaria geniculata(of special concern); and the
butterfly-weed, Asclepias tuherosa, little ladies' tresses, Spiranthes tuberosa, eastern lilaeopsis,
Lilaeopsis chinensis,New England blazing star, Liatris borealis, thread-leaved sundew, Drosera
filiformis, vetchling, Lathyrus palustris, and wild rice, Zizania aquatica, (on the watch list)
(WBNERR, 1993). The following subsections describe in more detail the physical characteristics
and biota of each of the four major surface water components of the watershed.
E.1.2 Waquoit Estuary
Waquoit Bay is located at the southern margin of the watershed, protected from Vineyard Sound by
a barrier beach east of the main inlet to the Bay, South Cape Beach, and Washburn Island, a barrier
island to the west of the inlet (WBNERR, 1989). Water from the Sound enters the Bay through
. two channels and the overwash breach mentioned above. Several brackish water ponds (Sage Lot,
Jehu, Hamblin, and Eel) connect to the Bay. Waquoit Bay is relatively shallow and salt marshes
occur in some areas along the margins of the coastal ponds and tributaries (according to aerial
interpretations of land use); saltwater wetlands covered 129 ha (319 acres) in 1990 (Cape Cod
Commission, unpublished; Appendix F). Bottom habitats include areas of open sand and mud, as
well as patches of eelgrass. , .
Eelgrass (Zostera marina) is a rooted vascular plant that grows subtidally on mud to gravel bottoms
in zones of fast moving or quiet waters where salinity ranges between 20 and 32 parts per
thousand. Eelgrass roots and rhizomes are believed to decrease erosion and increase
sedimentation, and eelgrass blades may act to promote deposition by interrupting water flow and
trapping suspended sediments, thus, adding to the available food within the meadow (Short, 1984;
1989). Eelgrass is highly susceptible to adverse changes in-water quality conditions and requires
clear waters with ample light penetration for photosynthesis and suitable levels of nitrogen and
phosphorus nutrients (reviewed in Dennison, 1987; Zimmerman et al., 1991; Murray et'al., 1992;
Dennison et al.,. 1993; Submerged Aquatic Vegetation Work Group, 1995). Eelgrass provides
optimum physical and chemical environmental conditions in a protective habitat for many fishes
and invertebrates (Valiela et al., 1992; Heck et al., 1989; Thayer et al., 1989). A variety of
bryozoans, sponges, and hydroids attach to eelgrass blades; numerous juvenile finfish, crustaceans,
and shellfish inhabit eelgrass meadows. Decaying eelgrass leaves provide food for the detritivores
in .the benthic community as well. Greater species richness and abundance has been found in
eelgrass beds than hi adjacent unvegetated areas in Waquoit Bay and Nauset Marsh on Cape Cod
(Valiela et al., 1992; Heck et al., 1989).
The overlapping biogeographic ranges are evident hi the waters of the estuary, with both year-
round residents and seasonal migrants in the finfish communities of Waquoit Bay. A 1968 survey
reported that Waquoit Bay had the greatest diversity of finfish species in comparison to nine other
Massachusetts estuaries (Curley et al., 1971). The resident species include such species as
mummichug (Fundulus heteroditus), striped killifish (Furidulus majalis), tidewater silverside
(Menidia beryllina), fourspine stickleback (Apeltes quadracus), and rainwater killifish (Lucania
parva), Of the 52 species collected in Waquoit Bay, these resident species comprise 35 percent of
the total, with these species dominating the abundance (46 percent) and biomass (41 percent) of the
overall finfish community (Ayvazian et al., 1992). Table E-l contains a list of fishes found in the
Waquoit Bay watershed., .
74 Waquoit Bay Watershed Ecological Risk Assessment
-------
The part-time residents represent a composite of estuarine spawners such as winter flounder
(Pleuronectes americanus), longhqrn sculpin (Myoxocephalus octodecemspinosus), scup
(Stenotomus chrysops), and tautog (Tautoga onitis); marine species which are estuarine visitors,
such as the sand lance (Amodytes americanus), summer flounder (Paralichthys dentatus), and
American pollack (Pollachius virens); nursery species or young-of-the-year, such as winter
flounder juveniles, mullets (Mugil cephalus), juvenile tautogs, menhaden (Brevoortia tyrannys),
Atlantic silversides (Menidia menidia), bluefish (Pomatomus saltatrix), and bay anchovy (Anchoa
mitchilli); and adventitious species which have a more southern distributions but which lack an .
apparent estuarine dependence, such as ladyfish (Elops saurus), halfbeak (ffemiramphus
brasiliensis), and crevalle jack (Caranx hippos). Alewives (Alosa pseudoharengus) and blueback
herring (Alosa aesivalis) cross Waquoit Bay on their annual spawning migrations to fresh water,'
and larger fish such as bluefish and striped bass (Morone saxitalis) enter in pursuit of smaller prey
fish. Many primarily marine fishes use the estuary in the winter as a spawning and nursery
ground. Bluefish, tomcod (Microgadus tomcod), white hake (Urophycis tenuis), and pollock
inhabit the bay as juveniles but are rarely present as adults (Boesch and Turner, 1984).
Shellfish species harvested in the estuary include bay scallops (Argopecten irradians irradians),,
found in the eelgrass habitat, and hardshell (Mercenaria mercenaria) and softshell (Mya arenaria)
clams, generally found in the sand and mud habitats, respectively. The biota of the estuary also ,
includes a variety of temperate and boreal species of planktonic and benthic algae and
invertebrates,.providing food resources for the finfish and shellfish, as well as terrestrial and avian
wildlife hi the watershed.
Numerous shorebirds use the barrier beach and coastal saltmarsh as an important stopover on their
spring journeys north to breeding grounds in Canada and on their fall journeys south to the
southern United States, Central and South America. Shorebirds appearing in abundance in the
spring and fall on Waquoit Bay's barrier beaches include black-bellied (Squatarola squatarola) and
semipalmated (Charadrius semipalmatus) plovers; sanderlings (Crocethia alba); dunlin (Calidris
alpina); semipalmated (Ereunetes pusillus), least (Pisobiafitsicollis), and western sandpipers
(Pisobia minutilla); ruddy turnstones (Arenaria interpres); willets (Catoptrophorus semipalmatus);
lesser (Totanus flavipes) and greater (Totanus melanoleucus) yellowlegs; and short-billed
dowitchers (Limnodromus griseus). Sharp-tailed sparrows (Ammodramus cudacutus), black-
crowned night-herons (Nycticorax nycticorax), snowy egrets (Leucophcyx thula), and mute swans
(Cygnus olor) are found in the saltmarshes. Several species of birds that use the waters -as nesting
or feeding grounds are state and federally protected species.
The piping plover (Charadrius melodus), listed as threatened,.and the least tern (Sterna antillarum),
listed as being of special concern, nest on South Cape Beach and Washburn Island. The roseate
tern (Sterna dougalli), a species listed as endangered, forages in the water and rests on the beach
proper (WBNERR, 1993; 1995).,
DRAFT-June 13, 1996 ' . .75
-------
Table E-l. Fishes of the Waquoit Bay Watershed. ,
Sources: A = Ayvazian et al. (1992); C .'= Curley et al. (1971);
= Hurley (1990, 1992).
Genus/ Species x ."'
Common Name -;
Opsanus tail
Fundulus heteroclitus
Fundulus majalis
Cyprinodon variegatus
Lucania parva
Menidia beryllina
Menidia peninsulae
Pungitius pungitius
Apeltes quadracus .
oyster toadfish
mummichog
striped killifish
sheepshead minnow
rainwater killifish
inland silverside
tidewater silverside
ninespine stickleback
fourspine tickleback
Reference
Genus/Species v . '..';
Estuarine Residents
A,C
A.C.H
A,C
A,C
A,C
A
C
A,C
A,C,H
Gasterosteus aculeatus
Gasterosteus
wheatlandi
Syngnathus Jiiscus
Mentidrrhus saxatilis
Gobiosoma bosci
Pholis gunnellus
Myoxocephalus
aenaeus
Trinectes masculatus
Sphoeroides maculatus
:Commpn Name :
Reference
threespine stickleback
blackspotted
stickleback .
northern pipefish (in
eelgrass)
northern kingfish
naked goby
rock gunnel
gruby
hogchoker
northern puffer
A,C
A,C -
. A,C
A,C
A
A,C
A,C
A,C
A,C
'- . . Estuarine Nursery
Clupea harengus
Brevoortia tyranntts
Anchoa mitchelli
Microgadus tomcod
Strongylura marina
Menidia menidia
Atlantic herring
Atlantic menhaden
bay anchovy
Atlantic tomcod
Atlantic needlefish
Atlantic silverside
A
A,C ,
A
A,C
A,C
A,C
Pomatomus saltatrix
Tautoga onitis
Tautogolabrus
adspersus
Mugil cephalus
Pleuronectes
americanus
Urophycis tends
bluefish
tautog
cunner
striped mullet
winter flounder
white hake
A,C
A.C
A,C
A,C
A,C
C
Diadromous (anadromoiis and catadromus) .
Anguilla rostrata
Alosa aestivalis
Alosa pseudoharengus
American eel
blueback herring
alewife
A.G.H
A,C
A,C
Alosa sapidissima
Asmerus moraax
American shad
rainbow smelt
\ .
A
C
Waquoit Bay Watershed Ecological Risk Assessment
-------
Table E-l. Fishes of the Waquoit Bay Watershed (continued).
Sources: A = Ayvazian et al. (1992); C = Curley et al. (1971); H = Hurley (1990, 1992).
Genus/ Species
Commori Naine -
Reference
Genus/Species .
Marine, Seasonal Visitors as Adults
Anchoa hepsetus
Pollachius virens
Morone saxatilis
Centropris'tls striata
Stenotomus chrysops
Mugil curema
Ammodytes'
americanus
striped anchovy
pollock
striped bass
black sea bass
scup
white mullet
American sandlance
A
A,C
A, C
A, C
A,C
A
A,C
Prionotus carotinus
Prionotus evolans
Myoxocephalus
octodecemspinosus
Paralichthys dentatus
Scopkthalmus aquosus
Limandaferruginea
'Common Name :
Reference
northern searobin
striped searobin
longhorn sculpin
summer flounder
windowpane
yellowtail flounder
A, C
A,C
C
A,C ,
A
A
Freshwater, Sometimes in Brackish Water
Fundulus diaphanus
Fundultts confluentus
Morone amcricana
Notemigoniu
crysoleucas
Notropis bifrenatus
Nottopis heterolepis
Catostomus
commersoni
banded killifish
marsh killifish
white perch
golden shiner '
bridle shiner
blacknose shiner
white sucker
A,C
A
A,C
C,H
A
A
C,H .
Etheostoma olmstedi "
Salvelinus fontinalis
Salmotrutta
S. fontinalis x S. trurra
Ameiurus nebulosus
Lepoms gibbosus
Micropterus salmoides
tessetated darter
"sea run" eastern
brook trout
brown trout
tiger trout (hybrid)
brown bullhead
pumpkinseed
largemouth bass
Adventitious Visitors
Slops saurus
Caranx hippos
Hemiramphus
brasiliensis-
lady fish
crevallejack
ballyhoo
A ;
A
A
Hyperogtyphe
perciformis
Gadusmorhua
Cyclopterus lumpus
ban-elfish
Atlantic cod
lumpfish
H
C,H
H
H
H
H
H
A
C
C
DRAFTJune 13, 1996
77
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E.1.3 Coastal Plain Rivers i
. ' -''. \ ' , .'.'
Coastal plain rivers also provide an important source of water for upland species and are prime
habitat for fishes, turtles, ducks, and geese. Forests of scrub oak and pitch pine are frequently
encountered in the surrounding soils, which are mostly consolidated sand dunes. The largest and
cleanest contributor of fresh water to Waquoit Bay is the Quashnet River (also called the Moonalds
River in Falmouth), which had an average streamflow of 391 L/sec (13.8 cubic ft/sec) or 8.9
million gallons per day from 1988 to 1991 (Barlow and Hess, 1993). The Quashnet originates in a
spring-fed cedar swamp at the top of John's Pond. Outflow from Johns Pond to the Quashnet can
be regulated by a gate-controlled spillway. From the pond, the river enters cranberry bogs, flows
east for 0.6 km (0.4 mi) then flows south for 5.6 km (3.5 miles) (Baevsky, 1991), finally emptying
into Waquoit Bay. ,
Besides providing a source of fresh water to Waquoit Bay, the Childs and Quashnet Rivers provide
a relatively rare and shrinking habitat for several anadromous and catadromous finfish species
(Baevsky, 1991). Brown trout (Salmo trutta), brook trout (Salyelinusfontinalis), alewife (Alosd
aestivalis), white perch (Morone americana) use these rivers as a conduit for spawning grounds
either within the rivers themselves or within John's Pond (McLarney, 1988; S.T. Hurley, 1994,
Massachusetts Divsion of Fisheries and Wildlife, pers. comm.). American eels (Anguilla rostrata)
use these rivers as a conduit for spawning grounds in the open sea. These species require very
specific ranges of certain water quality parameters (temperature, pH, dissolved oxygen, salinity)
which may vary over the stages of egg, larval and juvenile development (Hunter, 1991). Under the
care of the Northeast Chapter of Trout Unlimited, ecological integrity and stability in the Quashnet
have recently improved significantly. The river now hosts a 1.6 km- (1 mi-) long trout spawning
reach 3.5 to 5.3 km (2.2 to 3.3 mi) downstream from the spillway. The upper Quashnet River
receives constant temperature groundwater discharge through the sand and gravel bottom (USGS,
1991), which keeps river temperatures moderate, from 10 °C to 17.9 °C (50 °F to 64 °F) in the
spawning reach (Baevsky, 1991). Blueback herring, striped bass, and white sucker (Catastomus
are also commonly found in this stream. .
The characteristics of the high volume of ground water inputs into the Quashnet River significantly.
influence the water quality parameters of the river. At present, the waters seeping into the
Quashnet are fairly pristine, with a dissolved oxygen content of 9.3 to 12.6 mg/L, (well above the
minimum requirements for the most sensitive brook trout), pH between 6.0 and 6.4 (too low for the
Class B requirements), and a nearly constant temperature of 14 °C (57 °F) resulting from
groundwater seepage (Baevsky, 1991). For example, the temperature remained between 10 °C and
17.9 °C (50 °F and 64 ?F) hi the spawning reach during 1988 (Baevsky, 1991). In that same year,
the temperature entering the river from John's Pond was 26.3 °C (79 °F). the inputs from ground
water are also crucial to maintaining sufficient volume to the river for fish to move upstream.
The good water quality of the Quashnet River also provides habitat for a variety of
macroinvertebrates which serve as a food source for the finfish communities (Pennak, 1989). As
part of Trout Unlimited' s restoration project, macroinvertebrate species were reintroduced to the
Quashnet from other freshwater streams. A survey done in 1982-1983 found species representing
the Trichoptera (caddisfly), Diptera (true flies), Lepidoptera (butterflies and moths),
Ephemeroptera (mayflies), and Plecoptera (stoneflies) orders (Wright, 1987). Stoneflies, and to
some extent mayflies and caddisflies, are good indicators of healthy water quality as they require
fairly high levels of dissolved oxygen.
78 Waquoit Bay Watershed Ecological Risk Assessment
-------
E.1.4 Freshwater Ponds .
*'
Ashumet Pond and Johns Pond are coastal plain kettle hole ponds located within the WaquSit Bay
watershed, north of the bay itself. There are no surface outlets discharging from Ashumet Pond.
Ground water recharge occurs in the upgradient area and the pond recharges the ground water on
the downgradilnt side of the aquifer. Johns Pond connects to the Quashnet River by a. surface
outlet at a gate-controlled spillway. This spillway can draw down the level of Johns Pond to 1.2 m
(4 ft) below it average elevation. Ashumet Pond covers 82 ha (203 acres), with an average depth
of 7 m (23 ft) and maximum of depth of 20 m (66 ft); Johns Pond covers 131 ha (324 acres), with
an average depth of 5.9 m (19 ft) and maximum depth of 19 m (62 ft) (Duerring and Rojko, ,1984a;
1984b). . .
Fish populations including largemouth (Micropterus salmoides) and smallmouth (Micropterus
dolomeiui) bass, trout, and brown bullhead catfish (Ameiurus nebulosus) reside within Ashumet
Pond and similar fishes have been recorded in Johns Pond. Freshwater mussels are also abundant
in the ponds. A high diversity of phytoplankton is present in the photic zone, but limited vegetative
growth on the shorelines has been documented (HAZWRAP, 1994, 1995). Within the vicinity of
the ponds, several species have been designated as having special concern or threatened status,
including the sandplain flax, the marsh hawk, and the grasshopper sparrow . The upland sandpiper
is listed as a state endangered species.
E.1.5 Freshwater Wetlands
The freshwater wetlands of the Waquoit Bay watershed covered approximately 83 hectares in 1990
(Appendix F) and support many wetland plant and animal species. Important freshwater wetlands
include the Ashumet and Johns Ponds shorelines. Waterfowl are dependent upon these wetlands
for breeding, foraging and migratory needs. These habitats provide a valuable refuge for many
types of wildlife, including the osprey (Pandion haliaetus) which forages for fish hi freshwater
" areas. Many upland wildlife species are seasonally dependent on wetlands, including song and
game birds, opossum (Didelphis virginiand), raccoon (Procyon lotor lotof), and white-tailed deer
(Odocoilens virginianus).
E.2 Ecological Effects
The waters of Waquoit Bay and associated freshwater ponds are exhibiting signs of water quality
degradation and the diversity and abundances of key aquatic species have changed, notably during
the last 30 years. In the Bay, increased phytoplankton populations have decreased water clarity and
the amount of light penetrating the water. Extensive mats of macroalgae consisting mainly of the
species Cladophora vagdbunda and Gracilaria tikvahiae, which was unknown in the bay in 1969
(Curley et al., 1971), cover most of the bay (Valiela et al., 1992). The extent of eelgrass habitat
has declined, from approximately 81 ha (200 acres) in 1950 to only 16 ha (40 acres) hi 1987 (Costa
et al., 1992). Eelgrass is now restricted to fragmented beds near the mouth of the bay and the tidal
inlet near the mouth of the Eel River adjacent to Washburn Island, to the small salt pond and salt
marshes of Washburn Island, and to small patches in Hamblin Pond, Jehu Pond, and Sage Lot Pond
(Figure E-l). Physical destruction of eelgrass and saltmarsh has also occurred.
DRAFTJune 13, 1996
79
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80
Waauoit Bay Watershed Ecological Risk Assessment
-------
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DRAFTJune 13, 1996
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Water clarity has also been reduced by increased sediment participates released' into the Bay,
rivers, and ponds. Settling of unconsolidated participates has adversely affected nursery and
spawning habitats for fishes, as well as benthic invertebrate communities.
''''.
Alterations in the composition of species dependent on the eelgrass for nursery or adult habitat have
occurred, with declining abundance of commercially important finfish, such as flounder, pollack,
and hake, and shellfish, particularly the scallops. In July 1987, 1988, and 1990, fish kills occurred
in Waquoit Bay and the northern beach was covered with thousands of dead winter flounder,
shrimp, blue crabs, and other estuarine species (Sloan, 1992; D'Avanzo and Kremer, 1994).
Anoxic conditions in the Quashnet could constitute a barrier to sea-run brook trout (McLarney,
1988). Phytoplankton blooms in Ashumet and Johns Ponds have changed the color of the water
and depleted oxygen levels in the hypolimnion of the pond; fish kills occurred in Ashumet Pond hi
July 1985 and May 1986 (HAZWRAP, 1995).
Recent changes and reductions hi stream flow .have affected herring runs and trout streams (Barlow
and Hess, 1993). These species require certain quantities and depths of water; for example,
alewives that must travel to Johns Pond to spawn need sufficient water
depth to traverse the bogs near the pond and years of low water table levels or reduced flow have
limited their success. , .
E.3 Sourc.es and Stressors
Seven physical, chemical, and biological Stressors in the Waquoit Bay watershed were identified
during discussions with the risk management team and the public. The sources of Stressors include
human activities within and outside of the watershed. Each stressor was characterized on the basis
of its type, mode of action, and general ecological effects that might result from exposure to the
stressor. In addition, information on the intensity, frequency, duration, timing, and spatial
heterogeneity and extent (scale) were reviewed for each stressor in the watershed, if available. The
susceptibility of the ecosystems to the Stressors was also examined.
E.3.1: Sources of Stressors ,.
Anthropogenic Stressors in the Waquoit Bay watershed are the result of changing land use patterns
along the coastal and upland areas (Appendix F). Land use maps produced by the Cape Cod
Commission and by the LMER group identify land use with respect to commercial, cleared land
and recreation, residential, agricultural, forest, wetland, mining, waste disposal and transportation.
These maps also depict changing land use patterns with time. For example, in 1950 2% of the
watershed was residential; in 1990 20% was considered residential (Sham et al., 1995). Land use
hi the watershed is primarily residential, particularly along the Childs River (McDonnell et al.,
1994). In 1938, 785 houses had been built hi the watershed, but more than 8000 residences were
counted in the watershed by 1984. Around Waquoit Bay alone the human population has increased
approximately fifteen-fold hi the past 50 years, from 400 houses hi 1950 to over 4000 houses hi
1990 (Sham et al., 1995). More thari 3000 additional single-family homes could be constructed hi
the watershed (Waquoit Bay Watershed Citizen Action Committee, 1992).
Cranberry bogs, the major agricultural land use, have declined over the past century; today there
are less than 350 acres of bogs. Cranberry bogs, golf courses and cropland comprise 1.2 percent,
1.2 percent, and 2.0 percent of land use, respectively, in the watershed (Appendix F). The
Massachusetts Military Reservation (MMR) in the northern portion of the watershed (Figure E-3) is
82
Waquoit Bay Watershed Ecological Risk Assessment
-------
of special concern due to the contaminant plumes emanating from ten separate point sources; this
installation is the closest to an industrial or commercial land use classification in the watershed'
(HAZWRAP, 1995).
Although the Quashnet River has been recognized by some as an extremely valuable resource,
development pressure continues to build hi the surrounding towns of Mashpee and Falmouth and
with it the search for additional sources of drinking water. To restrict one proposed housing
development, the Commonwealth of Massachusetts purchased 146 ha (361 acres) of land along
the river, thereby limiting this housing development to 185 units without river frontage (Baevsky,
1991). Ashumet and Johns Ponds also face potential susceptibility to development pressure. The
watershed is particularly susceptible to buildup of nutrients and chemical pollutants because of the
porous soils of the watershed and the limited flushing of waters from the ponds-and the Bay (from a
few months to over 30 years). Development in the watershed has also increased human activities in
and on the surface waters, particularly in the ponds and bay. Stressors associated with atmospheric
deposition might also contribute to those already present from the various land and marine uses.
Residential Development. Activities hi the watershed associated with residential land use that
'might add to nutrient-loading within the ecosystem include bn-site septic systems; fertilizer use on
lawns, golf courses, and gardens; and housing and road construction with the attendant increase of
impervious surfaces (Valiela and Costa, 1988). Each of the 8000 homes in the watershed has an
on-site wastewater disposal (septic) system that contributes nitrogen to ground water which travels
to Waquoit Bay. Wastewater is a larger contributor of nitrogen to the estuary than is atmospheric
deposition or fertilizers (Valiela et al., 1996). Fertilizer inputs to Waquoit Bay are primarily from
residential lawn applications. Shellfish beds are frequently closed at the mouth of the Quashnet
River to protect consumers from potential exposure to human pathogens that are not trapped by
septic systems or soil and reach the bay. Pesticide applications on golf courses, cranberry bogs,
and lawns add toxic chemicals. Private and municipal well development alters ground water flow
regimes. Housing and road construction also are sources of sediments as construction uproots
vegetation and roads and driveways increase impervious surface cover. Oil hydrocarbons and
other chemicals can accumulate on impervious surfaces like parking lots and roads and be washed
off by rain to enter ground and surface waters.
Industrial Uses. MMR, composed of Camp Edwards and Otis Air Base, is located on the upper
western portion of Cape Cod and covers 8903 ha (22,000 acres). Past industrial and military
activities at MMR have mobilized chlorinated solvents and fuel constituents forming plumes of
contaminated ground water. MMR was added to' the National Priorities List (NPL) on November
21, 1989 (HAZWRAP, 1995). Sewage treatment facilities at MMR and increased runoff from
impervious surfaces add nutrients; well development might have altered ground water flow (Barlow
and Hess, 1993). Ashumet Pond is receiving its greatest input of phosphorous from the MMR
sewage treatment plant (STP). If phosphorous levels continue to remain as predicted over the next
ten years, Ashumet Pond will become eutrophic. Freshwater ponds could also be affected by other
contaminants associated with MMR (HAZWRAP, 1995).
Agricultural Activities. Agricultural practices are sources of nutrients via fertilizer application and
runoff from animal wastes. Other agricultural activities that affect .the ecosystem are the addition
of pesticides or herbicides, which can be toxic to aquatic life and water-dependent wildlife, and the
construction and use of flow control structures at Johns Pond for irrigating the cranberry bogs
along the Quashnet River, which can alter flow patterns, change the quantities of surface water hi
the ponds and streams, and add to sediment-loading. Migration of pesticide and other chemical
DRAFTJune 13, 1996 . 83
-------
constituents from an abandoned cranberry bog in the watershed could also contribute chemicals to
surface and ground waters (HAZWRAP, 1995). -,
MASSACHUSETTS
.v MILITARY
RESERVATION
^$x^
MUNICIPAL BOUNDARY H+H4fHi USCG .
MMR BOUNDARY I'.'tV.. J VETERANS AOMIN
CAMP EDWARDS - ARNG Wf/M USAF
OTIS - ANG
SCALE: NTS
DATE: ' 12-9-94
FI.PMAUP; .MURH377.0GN
Figure E-3. Location of the Massachusetts Military Reservation, North of Johns and Ashumet Ponds
(HAZWRAP., 1995).
84
Waquoit Bay Watershed Ecological Risk Assessment
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_ Aquatic Activities. Water-based activities also are sources of stressors to the estuarine and
* freshwater ecosystems (Waquoit Bay Watershed Citizen Action Committee, 1992; HAZWRAP;
1995; WBNERR, 1995). These activities include recreational boating, which is a source of
nutrients and human pathogens from on-board septic systems and toxic chemicals from leaching of
antifouling paint chemicals from boat hulls and spills of fuel and other discharges from marinas;
construction of docks and piers using lumber treated with heavy metals and other wood
preservatives or antifouling compounds, which can introduce toxic chemicals to the estuary (Figure
E-4); waterway maintenance, including dredging and shoreline modification, which adds
resuspended sediments; shellfishing in the estuary, which damages eelgrass habitat, resuspends
sediments, and contributes to harvest pressure; recreational fishing in the estuarine, riverine and
pond environments, which contributes to harvest pressure; and swimming in the Bay and Ashumet
and Johns Ponds, which can disrupt benthic communities and resuspend sediments. More than
2100 boats greater than 6.1 m (20 ft) in length are estimated to use the Bay and rivers (Waquoit
Bay Watershed Citizen Action Committee, 1992), with,an unknown number of smaller vessels
using the estuary and Ashumet and Johns Ponds.
Activities Outside of the Watershed. Several land and water use activities are not local or can
interact with local sources of stress. Armoring of the coast outside of the watershed changes
sediment deposition patterns along the barrier beaches of Waquoit Bay. Offshore fishing depletes
the stocks of commercially valuable species such as whiter and summer flounder, pollack, striped
bass and bluefish. Wet-and dry atmospheric deposition of nutrients and toxics can have sources
within and outside of the boundaries of the watershed. Automobiles, lawn mowers, and motor
boats generate NOx's locally. These atmospheric gases also originate hi coal-fired plants hundreds
of miles from the watershed. Nitrogen-containing atmospheric deposition adds nutrients to the
watershed (Valiela and Costa, 1988). Other toxic chemicals and metals can be adsorbed to
particulates from coal-fired plants, incinerators, and automobile exhaust fumes, settling in the
watershed. Mercury is a toxic chemical that also originates outside the watershed but is deposited
in the watershed where it can be methylated and accumulate in tissues of fishes and piscivorous
* wildlife (reviewed in Facemire, 1995; Fitzgerald, 1995; Hurley, 1995; and Weiner, 1995;
HAZWRAP, 1995).
E.3.2 Stressor Characteristics
Altered flow, sediment, physical destruction, nutrients, toxic chemicals, eelgrass disease, and
fisheries harvesting were identified as the major stressors affecting the ecological resources of
Waquoit Bay watershed. - ' . . -
Altered Flow (Riverine). Hydrologic modification is a physical stressor that results hi altered
stream flow patterns and reductions in the quantity of fresh water hi surface waters. Anadromous
and catadromous finfishes need sufficient water depth to traverse the shallow Waquoit estuary and
streams; sufficient fresh water is needed to sustain certain estuarine species that require reduced
salinities and prevent saltwater incursions in the ground water (Day et al., 1989; Milham and
Howes, 1994). Changes in the hydrology of the Waquoit Bay watershed can be sporadic,
depending on precipitation patterns, especially the number and intensity of hurricanes or
northeasters versus periods of drought, as well as seasonal requirements for.irrigation of cultivated
crops'. Long-term reductions in ground water occur from municipal wells that supply drinking
water to the residents from the western lens of the Cape Cod'Aquifer.
DRAFTJune. 13, 1996
85
-------
Dock counts
1993
Figure £-4. Dock Counts in Waquoit Estuary in 1993 (Data from R. Crawford, WBNERR).
Around the turn of the century, cranberry bogs were developed along the upper Quashnet River
and water flowing put of Johns Pond was controlled to provide water to the bogs as needed,
particularly in the fall for harvesting the cranberries. This land use altered the flow volume,
velocity, and path of the river resulting in loss of spawning habitat for anadromous fish species.
Cranberry bogs are often flooded in winter to prevent freezing and the water is then released in the
spring. While the spring release might counteract the effect of groundwater withdrawals, the
harvest flood waters are often released during the time of autumn spawning for trout (USGS,
1991). An extensive effort by Trout Unlimited and the Massachusetts Department of Fisheries and
Wildlife has restored major sections of the trout habitat, although some species have not been
restored. Alewives and blueback herring that swim to Johns Pond to spawn also need sufficient
water depth to traverse the bogs near the pond. Cranberry cultivation could be increasing at the
headwaters of the Quashnet in the near future.
In addition, the Quashnet and the ground water that feeds it are currently under pressure from
urban development (Barlow and Hess, 1993). Plans to develop a community drinking water well
could further alter flows and affect the ground water system (Barlow and Hess, 1993), including
thermoregulation of the temperature of spawning beds in the rivers, which protect the eggs of some
fish species. Longitudinal, lateral, and vertical changes in salinity patterns in the upper bay could
have affected the distribution of some estuarine fauna and flora (e.g., Schroeder, 1978; Welsh et
al., 1978; Day et al.,- 1989). Dredging activity in the channels leading into Waquoit Bay changes
water flow patterns and flushing rates between Waquoit Bay and Eel Pond, as well as the smaller
ponds (Aubrey et al., 1993). Changes in current patterns can lead to shoaling near the inlets to the
bay, primarily from flood deltas and secondarily from ebb deltas, that in turn affect current patterns
(Geyer and Signell, 1992; Fitzgerald, 1993).
86
Waquoit Bay Watershed Ecological Risk Assessment
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Sediment. Terrigenous and biogenic particles accumulating in aquatic ecosystems from lanid
runoff, erosion, and biological productivity are another physical stressor. Sediment can be easily
disturbed by currents, wave action, or organism movements, suspending particles in the water
column. The particle load is referred to as turbidity, which decreases light penetration through the
water, and the fine particulates can interfere with feeding and respiration in benthic and pelagic
aquatic organisms and feeding in visual predators. Particles can remain hi suspension as long as
the velocity of the water is sufficient to counteract gravitational forces. As water velocity
decreases, sediment particles settle, with heavier particles settling first; for example, swift flowing
streams can carry a higher sediment load that is then deposited when the stream empties into a
slower-flowing river or bay. Thus, fine-grained sediments are more likely to remain in suspension
longer, resulting hi increased turbidity. When the particles settle to the bottom, deposition on
surfaces of sedentary plants and animals, as well as the bottom, can cover organisms that might
have a difficult time removing the particles and alter habitat features, for example, changing gravel
bottom to mud (NRC, 1992).
Changes in sediment loading and deposition in the watershed occur frequently, in concert with
changes in precipitation, surface water volumes, wind- or water-driven current patterns, and
construction or other human activities. Acute changes in sedimentation can occur after catastrophic
natural storms such as hurricanes (Hayes, 1978) and after dredging or construction activities;
chronic increases hi sedimentation result as sediments are resuspended by currents in shallow areas.
Swimming and burrowing activities of aquatic organisms can also influence sediment deposition
and resuspension (e.g., Yingst and Rhoads, 1978). Resuspended sediments can reintroduce
adsorbed nutrients and toxics to the water column.
The quantity of sediment entering the surface waters of Waquoit Bay watershed from runoff and
rivers is unknown. Runoff is not thought to be a problem, since water readily percolates through
the sandy soil. Reductions hi streambed permeability might occur if fine-grained sediments deposit
in spawning areas of the rivers (Baevsky, 1991), limiting gas exchange from the eggs with the
surrounding water. Increased turbidity from suspended and resuspended sediments has reduced
light levels needed for photosynthesis by eelgrass hi Waquoit Bay, although eelgrass could grow,
slowly, at 10 percent of surface light intensity (Short et al., 1989; Giesen et al., 1990). Sediment
particles also increase the potential stress on eelgrass because epiphytes growing on eelgrass blades
are good depositional surfaces for suspended sediments (Home et al., 1994). Suspended sediments
might also weight down the eelgrass blades causing them to sink to the bottom where they can die
from insufficient light or suffocation (Kemp et al., 1993; Short, 1989).
Protecting the coast from erosion by building of jetties and groins has several effects on estuarine
habitats. Jetties and groins alter regional.sand and other sediment transport and sedimentation
patterns (WBNERR, 1995). These alterations can have a negative impact on barrier beaches, salt
marshes, and eelgrass beds,, all habitats for estuarine or water-dependent wildlife. Shoaling near
inlets to the bay has occurred from dredging, also changing sedimentation patterns (Fitzgerald,
1993). These activities might also adversely affect eelgrass beds in lower Waquoit Bay.
Loss of eelgrass, hi turn, also can change sediment depositional patterns since eelgrass beds
enhance sediment deposition (Short, 1984; 1989). The distribution and abundance of many benthic
organisms can be adversely affected by sediment deposition. For example, softshells or steamers .
grow best hi fine muddy sediments, but they are more susceptible to predation hi these habitats
(Funderburk et al., 1991). Siphon-clogging problems might occur hi mud substrata which can
offset rapid growth rates hi these sediments (Emerson et al., 1988). Hard clams or quahogs grow
best hi sandy sediments, since higher water currents provide more food to these suspension feeding
DRAFTJune 13, 1996
87
-------
organisms (Rice and Pechenik, 1992).. Juvenile quahogs lack extensible siphons and attach to sand
grains with byssal threads to permit them to feed at the sediment surface. Despite this affinity for;
sandy to muddy sand sediments, adult quahogs are found in a variety of sediment types, with
grayely sediments providing protection from predators. The thick shell, lack of shell gaping, and
benthic burrowing limit the predation on these clams. It is not known whether changes in the
composition of the substratum have altered community structure to increase shellfish predation.
Physical Destruction. Direct and indirect alteration of habitat structure is a physical stressor that
results in changes to me physical, chemical, and biological conditions that support the survival,
growth, and reproduction of different species of plants and animals in a community. In addition to
hydrologic modification, changes in current and flow patterns, and increased sedimentation, several
other mechanisms can alter the estuarine habitat'in the Waquoit Bay watershed, with subsequent .
effects on the organisms (Day et al., 1989). These activities occur sporadically; the changes in
conditions brought about by physical destruction can be short- or long-term, but restoration of the
habitat to its structure and function prior to destruction might be impossible (NRC, 1992).
Shading by docks built from shore into the estuary, particularly in Great River, a tributary of
Waquoit Bay, decreases light penetration, adversely affecting eelgrass (Biirdick and Short, 1995).
This is not considered a major stressor on eelgrass or other aquatic life in.Waquoit Bay, however,
since the area covered by docks is small-less than 1 percent of the surface water area in Waquoit
Bay, its tributaries, and ponds (WBNERR, 1995). Mechanical disruption from clam digging, boat
props, and moorings can cut eelgrass blades or uproot eelgrass plants resulting in death of eelgrass
itself Habitat fragmentation from these activities affects organisms that reside in eelgrass
meadows. On land, construction of roads near the estuary can stop the landward progression of
salt marshes with deleterious effects on inhabitants.
Nutrients. Nearshore waters worldwide are receiving increased .releases of nutrients, particularly
nitrogen, from coastal watersheds (e.g., Nixon et al., 1986; Valiela et al., 1990; USEPA, 1994).
Eutrophication, especially nitrogen enrichment in estuarine ecosystems and phosphorus enrichment
in freshwater ecosystems, has been implicated as a major cause of phytoplankton and nuisance
macroalgal blooms (Day et al., 1989; Batiuk et al., 1992; NALMS, 1992). Inorganic nitrogen and
phosphorus, primarily in the form of nitrate and phosphate, are essential for the growth of
photosynthetic algae and plants, in addition to inorganic carbon, silicon, and other compounds
(reviewed in Goldman, 1974, and Day et al., 1989). In the aquatic environment, nitrogen is
converted to various forms through complex biogeochemical cycles that reduce or oxidize the
elements or transform organic compounds to inorganic states, including decomposition and
excretion (of organic forms, ammonium, and phosphate), bacterially-mediated nitrogen fixation
(reduction of inorganic nitrogen to ammonium), nitrification (oxidation of ammonium to nitrate),
and denitrification (conversion of nitrate to nitrogen gas by anaerobic processes). Phosphorus is
cycled through dissolved inorganic phosphorus, particulate organic phosphorus, and dissolved
organic phosphorus states involving plants and complexation with metals in sediments. Plants
assimilate nutrients and produce biomass by various biochemical reactions during photosynthesis ,
and, these reactions are driven by the quantities of nutrients available until they are saturated;
usually the concentration of one or more nutritional substances is less than its saturation level,
limiting photosynthesis and plant growth. Day et al. (1989) rioted that aquatic plants have adapted
to the average nutrient concentrations to which they have been exposed.
As noted above, the sources, pathways, and fate of anthropogenic nitrogen are related to land use
patterns and hi part to local and regional geology. Much of the nitrogen is believed to be
attenuated during passage through the Waquoit Bay watershed via volatilization, uptake by flora
88
Waquoit Bay Watershed Ecological Risk Assessment
-------
and fauna, adsorption, and denitrification (see Rhodes et al., 1985; Nixon and Lee, 1986;
Seitzinger, 1988; Reddy et al., 1989; WBNERR, 1993). The porous, sandy soils of this watershed
promote rapid percolation of precipitation with the result that there is little run-off from surface
sediments (Strahler, 1968; Valiela et al., 1990; Oldale, 1992). Thus, nitrogen, added either by
precipitation or dry deposition, rapidly enters the ground water and can. travel to Waquoit Bay
(Figure E-5). In a like manner, septic system and fertilizer additions of nitrogen and phosphorus
also penetrate the soil and make their way to the ground water and to Waquoit Bay (Valiela et al.,
1996). Microbial decomposition of biogenic material and direct excretion by animals into the
ponds, rivers, and estuary are biological sources of nutrients. These processes interact with
chemical processes occurring in the water column and sedimetns related to oxidation and reduction
of the nutrients to increase or decrease the quantities and forms of nutrients available in the
Waquoit Bay watershed (HAZWRAP, 1995). ' .
Ground water concentrations of nitrogen are higher in more developed areas on Cape Cod than in
less developed areas (Figure E-6) (Persky, 1986). In the Waquoit Bay complex, subwatersheds can
be identified which have experienced different rates of nutrient loading due to different patterns of
land use. Ground water concentrations of nitrogen are higher hi the more developed than in the
less developed subwatersheds (Table E-2) (Valiela et al., 1992; Rudy et al., 1994). Different ratios
of dissolved organic nitrogen (DON) to dissolved inorganic nitrogen (DIN) were found in the
ground water of the Waquoit Bay watershed, with the most urbanized subwatershed, the Chflds
River, having a ratio of 1:2, and the least urbanized, Sage Lot Pond, having a ratio of 7:1 (Rudy et
al., 1994). DON also appears to.be influenced by the presence of salt marsh, creating anoxic
ground water and increasing the accumulation of DON. Ground water travels at the rate of 13 feet
per day in the watershed. Houses built very close to the shore have the greatest impact on nitrogen
loading to the bay. Year-built data and proximity to shore data show that nearshore areas were "
developed first and are the most densely developed (Sham et al., 1995).
Table E-2. Nitrogen Levels in Groundwater of the Childs River Subwatershed Compared to that of
Sage Lot Pond.
* >.>' 1 . , ,
Nitrate Concentration in Jim
Measurement
Maximum
Average
' Minimum
Chflds River
736.38
440.85
162.81
Sage Lot Pond .
29.24
13.15
2.6 -.
DRAFTJune 13, 1996 . 89
-------
**
-------
c
0)
o
c
o
o
10
o
-2
.s
-------
Residential septic tanks could also be responsible for the additional input of naturally occurring
nutrients such as phosphorus and nitrogen into both of the freshwater ponds. TheMMRSTP .
plume has been identified as the primary source responsible for increased levels of phosphorous to'
the ground water discharging into Ashumet Pond (HAZWRAP, 1995). Since 1936, the disposal of
treated sewage from MMR has been accomplished through infiltration beds to a sand and gravel
aquifer, creating a plume of contaminants 914 m (3,000 ft) wide, 23 m (75 ft) deep, and more than
3353 m (11,000 ft) long, including high levels of sodium, chloride, nitrogen, detergents, and other
sewage-related compounds (LeBlanc, 1984; LeBlanc et al., 1991). Fate and transport of
contaminants in these plumes has proven very difficult to evaluate due to the influence of the two
large kettle hole ponds, Ashumet and Johns Ponds, on ground water flow. Contaminants appear to
be both discharging to the ponds and migrating under the ponds. The USGS is currently evaluating
the current and future impacts of phosphorus on Ashumet Pond; the concentrations'of phosphorus
hi the hypolimnion are higher in Ashumet Pond than Johns Pond, but preliminary studies suggest
that phosphorus might not be limiting here (Table E-3) (HAZWRAP, 1995). The Quashnet River
and Waquoit Bay are potential future locations for ground water discharge of MMR plume
contaminants in the absence of remediation.
Atmospheric NO3 and SOX deposition are either directly deposited to surface waters or are .
transported in terrestrial runoff and drainage into ground water. The latter transport pathways
threaten to lower pH levels in the Quashnet River and other surface water- or ground water-fed
streams in the watershed because there is very little natural buffering capacity in the glacial soils.
The pH of the Quashnet is in the range of 6.0 to 6.4, which is not in the optimum range for brown
and brook trout and does not meet the Massachusetts Surface-Water Quality standards of 6.5 to 8.0
for Class B streams (Baevsky, 1991). The major limitation for assessing the potential ecological
effects of nutrients on the Quashnet River is the paucity of available data.
Conversely, ecological effects of nutrients in the ponds and the bay have beensextensively studied.
Phytoplarikton blooms have appeared in these ecosystems (HAZWRAP, 1995; WBNERR, 1995).
Increased phytoplankton productivity decreases light penetration, altering the-light regime for
submerged aquatic vegetation (Batiuket al., 1992). Macroalgal mats, consisting of the fast-
growing species Cladophord vagabunda and Gracilaria tikvahiae are present in the shallow bay
bottom adjacent to highly developed land areas, particularly the lower Childs and Quashnet Rivers
(Table E-4). Epiphytes have grown on eelgrass blades (Valiela et al., 1992; Peckol et al.; 1994),
leading to reductions in the size of eelgrass patches in the bay (Orth and Van Monffrans, 1984;
Costa, 1988; Burkholder et al., 1992; Short et al., 1992; Valiela et al., 1992; Boxhill et al., 1994;
Hurlburtetal., 1994). Nutrients might not be the only factors influencing phytoplankton and
macroalgal growth in the ponds'and bay, since altered/low ground and surface water flow, changes
in the distribution and abundance of herbivores, and light penetration (which changes daily and
seasonally) could also affect the abundance and distribution of key aquatic flora (reviewed in
Cambridge and McComb, 1984; Cambridge et al., 1986; Day et al., 1989; Neckles et al., 1993;
Boxhill etal., 1994). ,
92
Waquoit Bay Watershed Ecolqgical Risk Assessment
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Table 3. Nutrient loading from the Massachusetts Military Reservation. N + P data extracted from
Figures 7.26 through 7.29, Volume H (UAZWRAP, 1995). Biology data extracted from pages 79-.80,
Volume I, and Figures 7.24 and 7.41m volume n (HAZWRAP, 1995).
Site
November 1992
Johns Pond
Ashumet Pond
April 1993
Johns Pond
Ashumet Pond
.; '"''"' Nutrients
Total
DIN ,
Mg-N/L
-60
-40
<:~67
-750
NH, .
^g-N/L
-10
-3-
<5-57
<5
NO^l;:;.
>g-N/L;
-50
-38
,v;' : :
14209
14534
331.5
"' Chlorophyll --;.:..
concentrations at mouth
x:;''.;':v(mg' iff?)::-':,,' '
25.5 ± 7.6
5.9 ± 1.7
3.9 ± 1.2
; : Total ntacroalgal ;
biomass (g m-*)
335 ± 39.8
150 ± 14.3
90 ± 12.1
Eelgrass biomass
-------
.Finfish and shellfish are at indirect risk from effects of nitrogen loading. Macroalgal mats provide
poorer quality finfish habitat than eelgrass beds for many resident finfish and for young-of-the-yeaf
part-time resident finfish (WBNERR, 1995). Small fish can become trapped in the tangle of algal
filaments (Sloan, 1992). Although photosynthesis by the algae on sunny days replenishes the.
oxygen, continuous cloud cover for several days can produce hypoxic or anoxic conditions under ;
the algal mats and send fishes into shallows where dissolved oxygen levels are higher (Valiela et
al., 1992). Johns Pond is classified as oligotrophic/borderline mesotrophic; Ashumet Pond is
classified as mesotrophic and the hypolimnion becomes oxygen deficient as a result of increased
decomposition during summer stratification (Ashument Pond Trophic State and Eutrophication .
Control Assessment Report, 1987, cited in HAZWRAP, 1995). Fish kills occurred in Ashumet
Pond in July 1985 and May 1986. Mass mortalities of finfish and shellfish occurred in the upper
reaches of Waquoit Bay during July 1987, 1988, and 1990. Valiela et al. (1992) also noted that
reduced photosynthetic activity by the macroalgal mats resulted in higher nutrient concentrations in
the water column followed by a bloom of phytoplankton during a July 1988 prolonged overcast
period. Preliminary measured rates of gross phytoplankton production and gross ecosystem
production in the lower Quashnet River varied with time and decreased hi response to a complex
suite of physical factors (Harrison et al., 1994).
The benthic faunal community is affected by nutrient enrichment hi two ways. First, hypoxic and
anoxic bottom water resulting from increased algal and microbial respiration, particularly during
cloudy days and nights in summer months, can produce physiological stress and cause mortalities hi
benthic community organisms (D'Avanzo and Kremer, 1994). All life stages of hardshell clams
appear to be susceptible to low dissolved oxygen levels hi the water, with growth rates of larvae
being reduced below 4 mg/L dissolved oxygen (Funderburk et al., 1991). Adult clams can tightly
close thek shells and respire anaerobically in anoxic bottom sediments hi order to withstand these
episodic events, but they generally fare better when dissolved oxygen levels in the overlying water
exceed 5 mg/L (Funderburk et al., 1991). Second, although hard and soft clam growth rates from
cleared bottom areas can increase hi response to higher nutrient inputs and increased phytoplankton
production (Chalfoun et al., 1994; Harrison et al, 1994), loss of eelgrass beds creates a loss of
habitat that provided shelter, refuge and a food source for many fishes and invertebrates (Valiela et
al., 1992). Other changes hi estuarine benthic communities have also resulted from eutrophication,
(Frithsen, 1991). Invertebrate species abundance and diversity is lower in areas without eelgrass hi
Waquoit Bay (Valiela et al., 1992).
The loss of eelgrass appears to be directly related to the success of scallop larvae. The bay scallop
larvae attach by byssal threads to eelgrass blades and the small juvenile scallops tend to move up
the eelgrass blade to escape benthic predation by crabs, starfish, oyster drills and whelks (Pohle et
al., 1991; Garcia-Esquiyel and Bricelj, 1993). Byssal thread attachment by juveniles is reversible
and dynamic, allowing the young scallops to keep pace with the growth of the eelgrass blades,
which turn over rapidly during the summer. Rapid growth of juvenile scallops occurs during this
attached phase that can last a couple of months (Pohle et al., 1991). This stage is followed by
descent to the sediments at the base of the blades, at which tune an epibenthic existence without
byssal thread attachment occurs. Adult bay scallops can occur hi eelgrass beds or over bare sandy
substrate (Garcia-Esquivel and Bricelj, 1993). Heavy predation by mud crabs (Dispanopeus sayii),
green crabs (Carcinus maenas), spider crabs (Libinia sp.), and mobile predators (northern puffer
Sphaeroides rnaculatus) and brachyuran crab (Ovalipes ocellatus) occurs on the small, epibenthic
scallops which have shells and are incapable of complete or provalve closure (Garcia-Esquivel and
Bricelj, 1993). Thus, scallop populations tend to be limited by predation on the attached
larvae/small benthic juveniles and water quality affects the pelagic larvae (MacKenzie, 1989).
94
Waquoit Bay Watershed Ecological Risk Assessment
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Toxic Chemicals. The biota of the watershed could be exposed to potentially toxic and
bioaccumulative chemical contaminants. Toxic substances are materials that are capable of
producing an adverse response in a biological system, altering or impairing its structure or function
or producing death (Rand, 1995). Toxics can affect the induction or inhibition of enzymes and/or
enzyme systems within the cell, hi turn altering the functions of these enzymes. Enzyme
dysfunction leads to disruption of metabolic processes including, but not limited to,
phosphorylation, uptake, or detoxification reactions, which is reflected in reduced/increased.
production of cellular constituents, changes hi cell cycling and replication, and degeneration of
celiular and nuclear membranes. Effects produced by toxic chemicals are dependent on the
concentration of the chemical and duration of exposure, as well as the type of chemical, its fate and
transport in the environment, and other factors. Sublethal effects of toxics include changes hi
behavior, growth, development, and reproduction of individuals, that ultimately affect the relative
distribution, abundance, and physiological condition of populations within aquatic communities.
Genotypic and phenotypic-factors operating withb individuals affect their susceptibility to different
toxicants and ability to metabolize the chemical to produce other compounds of reduced or greater
toxicity. Some compounds, particularly the more hydrophobic/lipophilic ones, are not readily
broken down hi the environment or by organisms and accumulate in the fatty tissues. Toxic effects
then occur when the concentrations of compounds are relatively high or the chemicals are released
when fats are metabolized, as during starvation.
The majority of the information concerning toxic chemicals hi the Waquoit Bay watershed is
focused on the contribution of contaminated ground water emanating from the MMR (HAZWRAP,
1995). Johns Pond and Ashumet Pond are located south of MMR and are subject to potential
contaminated ground water flow from the mam industrialized portions of the base including
flightline and fueling areas, and open storm drainage ditches. Water moving down through soil
contaminated by past industrial and military activities at MMR has mobilized chlorinated solvents
and fuel constituents forming plumes of contaminated ground water. Several of these plumes are
migrating within the Waquoit Bay watershed (Figures E-8 and E-9). Several study sites or areas of
concern (AOC) are under investigation north of the ponds and the plumes could potentially affect
both human and ecological receptors: These sites include: Fire Training Area 2/Landfill-2 (FTA-
2/LF-2), the Petroleum Fuel Storage Area (PFSA), and Storm Drain-5 (SD-5) (HAZWRAP, 1995).
For purposes of this investigation.all of the above described plumes within the Waquoit Bay
watershed have been grouped together as the Southeast Regional Ground Water Operable Unit
(SERGOU). SERGOU plumes originate from FTA-2/LF-2, PFSA and SD-5 and for discussion of
the conceptual model, SD-5 will be combined with runoff from cranberry bogs because of the
similar stressors, response pathways and resulting ecological effects. Areas of concern FTA-2 and
LF-2 occupy 20 acres of land used for fire-training exercises that were conducted on the top of a
former industrial/municipal landfill. Compounds disposed of hi the landfill or burned on the fire-
training area consist of fuel, waste oils, waste petroleum distillate solvents and domestic refuse.
The PSFA is an active facility that is involved in the delivery of various types of fuel and was the
site of a 2,000 gallon fuel spill hi the 1960s (ABB, 1991).
The contaminants from these plumes would affect the northern boundaries of the ponds'. Primary
ground water contaminants of concern within SERGOU include chlorinated solvents and volatile
organic compounds such as methanol (Table E-5). Preliminary studies, however, indicated that
levels' of volatile and semivolatile organics hi surface water and sediments at these locations hi the
ponds were not elevated compared to other sites hi the ponds hi 1993. Further, it appeared that
some of the detected compounds were introduced as contaminants during laboratory processing of
the samples, e.g., di-n-butylphthalate and bis(2-ethylhexyl)phthalate detected hi Ashumet Pond in
April 1993; methylene chloride, zinc, and chloroform detected hi Johns Pond hi April 1993): The
DRAFTJune -13, 1996 95
-------
greater number of samples collected in August 1993 in Ashumet and Johns Ponds did not greatly
increase the number of contaminants detected in the surface water. Neither trichloroethylene nor its
metabolite, tetrachloroethylene, nor the common fuel constitutents of the plumes (e.g., benzene,
toluene, and xylene), were detected in fish tissue or freshwater mussel tissue collected from the
pond (HAZWRAP, 1995). The Quashnet River and Waquoit Bay are potential future sites for
MMR ground water discharge effects in the absence of remediation and therefore the contaminants
in the plumes pose a threat to estuarine receptors. . . .
Little data are available on the quantities and effects of pesticides, polynuclear aromatic
hydrocarbons, polychlorinated compounds, and heavy metals suspected of being present in the
water, sediments, and biota in the ponds, rivers and streams, wetlands, and estuary. The water
released from the cranberry bogs has contained pesticides and other contaminants that are toxic to:
trout and other fish species and the macroinvertebrates oil which they feed (MBL Science, 1985).
Pesticides from the.MMR SD-5 area are primarily insecticides, rodenticides, and herbicides.
Pesticides within the water column can bioconcentrate in aquatic organisms and accumulate in
sediments, bioaccumulate in fish, mussel, or other invertebrate tissues and affect terrestrial wildlife
that prey on these organisms, such as racoons and osprey. Concentrations of PCBs and the
chlorinated pesticides ODD and DDE were.higher in fish from Ashumet Pond than those from
Johns Pond, but all pesticide residues were within the range for comparable reference sites
(HAZWRAP, 1995). Analyses of fish enzymes and freshwater mussel lipids did not indicate
exposure to high concentrations of chemicals; catfish from both ponds exhibited a high incidence of
papillomas on their jaws and around their mouths and adenocarcinomas were found in the livers of
two catfish from Johns Pond (Table E-7). The causes of these lesions could be contaminants,
viruses, and/or genetic factors (Harshbarger and Clark, 1990; Baumann, 1992). Heavy rainfall can
result in short-term increases and transport of elevated concentrations of chemical contaminants.
These types of episodic events could cause lethal effects to biota.
Another toxic of concern in the watershed is the bioaccumulative and neurptoxic metal mercury. A
concentration of 1.2 mg/kg was detected in one largemouth bass fillet during a study of the
chemical contaminants hi Ashumet and Johns Ponds (HAZWRAP, 1995). This concentration
exceeded the U.S. Food and Drug Administration action limit of 1.0 mg/kg to protect human
health. Deposition of mercury into surface waters and accumulation hi sediments might produce
sublethal effects hi pelagic and benthic aquatic organisms, as well as piscivorous wildlife.
96
Waqupit Bay Watershed Ecological Risk Assessment
-------
Massachusetts
Military
Reservation
Groundwater Phune
Watershed Boundary
-, I
AshumetPpnd
Figure E-7. Groundwater plumes in the Waquoit Bay watershed.
DRAFTJune 13, 1996
97
-------
, SOUTHEASTERN
"~ PLUME
JOHNS ?QND
ASHliMETi ?CND
FUEL GROUNDXATER PLUft
SOLVENT GROUNDWATER PLUliC
GREATER' THAN 5 ug/L
GREATER THAN 20 ug/L
GREATER THAN 100 ug/L
GREATER THAN 1000 ug/L
GREATER THAN 5 ug/L
NTS
12-15-94
GREATER THAN 20 ug/L
GREATER THAN 100 ug/L
FILENAME: HMRH333.0GN
GREATER THAN 1000 ug/L
Figure E-8. Groundwater plumes as in Figure E-8, showing the plumes from the SERGOU hi the
vicinity of Ashumet and Johns Ponds (HAZWRAP, 1995).
98.
Woquoit Boy Watershed Ecological Risk Assessment
-------
Table E-5-1. Chemical contaminants in ground water from the Massachusetts Military Reservation,
Data from Monitoring Well Fence 4, Figures 7.1 through 7.6, Volume H, HAZWRAP (1995). NJ> -
Not detected. -
.' ('.. '."^ .weiis-' : __;./ .- '.,;.; '.'...;" ' . ;. .
': .MW-528; "MW-S22-:::.' -MW-519--- . ' MW-51S ' MW-523 .'
VOC G"g/L)
Tetrachloroethene
cis-l,2^DicWoroethene
1 ,2-Dichloroethane
Trichloroethane
Chloroform
Total Xylenes
Benzene
Ethylbenzene
1,2-Dichloroethene (total)
SVOC O^g/L)
Di-n-butyiphthalate
Naphthalene
2-MethyInaphthalene
TPH^g^)
ND
*
ND
ND
3
ND
ND
1-2
8
0.6
16
1
0.6
ND
1
0.6
0.7
*
0.3
3
2-43
2
11 >
0.3
-
5
11
ND
Dissolved inorganics' (ug/L) '
Ca .-
As
Fe
Mn
11200
33000
11
7050
1250
7.9-19.8
1050-28,200
400
Total inorganics1 (pgfL)
Cu
K
Fe
As
Mn
Cd .
Pb
46
.
1630-2230
178-788
*'
75.4-8600
13
1450
7560-27,200
5.4-19.8
214-380
3.3
3.4
DRAFTJune 13, 1996
99
-------
Table £-5-1. Chemical contaminants in ground water from the Massachusetts Military Reservation.
Data from Monitoring Well Fence 4, Figures 7.1 through 7.6,-Volume n, HAZWRAP (1995). ND =
Not detected (continued).
Wells
MW-528 MW-522 MW-519 MW-518 MW-S23
Mg
'5630
Nutrients (Mg/L)
SRP2
TSP2
NH43
NO33
26.23-26.39
25.07-29.87
0.19-0.63
572.1-1397
4.19-22.64
6.13-1387 .
0.14-0.68
396-1615
23.62-43.21
21.07-35.73
0.09-0.10
1931-2085
6.15-21.33
8.8-19.73
0.05-19181
2.82-2014
1 Values exceeding background levels
2 As P - '
3 As N
Table E-5-2: Monitoring Well Fence 2 (Figures 7.7 through 7.12, Volume n, HAZWRAP, 1995).
." , ' Wetts
MW-540 MW-53» MW-543 MW-544
VOCfcg/t)
Chloroform
Trichloroethene
Methylene Chloride :
Tetrachloroethene -
Trichloroethene
SVOC (Mg/L)
TPH Ut&flL)
2
0.8
2
ND
ND
.
2 *'
ND
ND
0.6
0.9
ND
ND
1
3
ND
0.7-0.9
Dissolved inorganics1 (Mg/L) ,
Fe
Mn . '
K '"'-.' ' . ' :
Mg ' .
Al '
72.6
500
1680
4830
.
(
103
,,
606
. Total inorganics1 (Mg/L) .
Fe ' . ....'
145
315
100
Waquoit Bay Watershed Ecological Risk Assessment
-------
Table E-5-3. Monitoring Well Fence S (Figures 7.T2tfci»H!P
[continued).
MW-540
Mn
K
Pb
Zn
A!
456
1910
MW-539 MW-543 ;
1600
5:2-5.8
105
802
'MW-S44- '
,
Nutrients (A*g/L) ' .
SRP1
TSP1
NH<3
N033
5.17-25.58 .
8.27-26.67
0.41-6.68
40.64-3521
3.05-23.29
6.67-23.47
0.25-1.96
1551-3260
8.76
10.67 ,
1.55
1032
1.25-28.19' .
5.07-31.2
0.36-39.26
14.74-1977
1 Values exceeding background levels
2AsP
JAsN
Table E-5-3. Monitoring Well Fence 5 (Figures 7.13 through 7.18, Volume n, HAZWRAP, 1995).
. - ' W*Hs
MW-52S MW-S41 MW^ZI MW-52« MW-524
VOC (vgTL)
Trichloroethene
Chloroform
1 ,2-Dichloroe thane
SVOC Ozg/L)
Di-n-butyphthate
TPH(Azg^L)
Dissolved (ngTL)
inorganics
K
Fe
Mn
Ca
Ba
As
11
1
0.4-0.6
0.7
ND
ND
1640
'
605
413
18300
ND
~
ND
',
0.4
25
0.5
2
0.4-0.6
10-59
0.5
ND
0.3
2310
276
72
4.2
1770-3040
28,500-39,500
DRAFTJune 13, 1996
101
-------
Table E-5-3. Monitoring Well Fence 5 (Figures 7.13 through 7.18, Volume n, HAZWRAP, 1995)
(continued)
. .,.';;>;-: .' Weils
MW-S25 MW-541 MW-521 MW-526 MW-S24
Mg
Mn
Total inorganics' (^g/L)
K ;':~ ' -'
Mn
Fe
Ga . ,
Ba ',
As
Mg
Al
Be
Cr
V
Nutrients
SRP2
TSP2
NHi3
NO,3
1600
1.9-33.58
18.67-35.47
0.83-2.59
158.8-1939
< '
368
90.7
16700
2.88-35.37
0.05-33.6
0.94-51.15
240.7-1404
51.37-71.29
48.27-60.27
0.32-0.69
13.25-111.6
2260
137-514
68.7
6.5
2.56-15.62
9.87-20
2.027-15.09
662-4248
5030:5740
250-443
5480
254-597
158-14,500
28,600-37,100
8.4
4950-8260
11000
1.4
24.4
26.5
24.44-73.90
29.33-65.87
0.04-24.78
889.4-1622-
1 Values exceeding background levels
2AsP
'3AsN '
102
Waquoit Bay Watershed Ecological Risk Assessment
-------
Table E-6-1. Chemical contaminants in Ashuraet and Johns Ponds (Volume n, HAZWRAP, 1995,
Figures 7-33). ' , .
Ashumet Pond April 1993 i
. ., ':' APSW-1 .;';':- .'-^-APSW^^Xr^ ''APSWO'rV'';-::'''ii-.'.;>APSW-4' ''':.;.'"..
Water concentrations in /ug/1
VOGs
SVOCs
Di-n-butylphthalate
Butylbenzylphthalate
PEST/PCBs
ND
1
ND
ND
1
-
ND
ND
ND
ND
ND
1
ND
Metals
Mn
NA
34
8660
35.7
8780
34.6
8630
29.9
8860
Ashumet Pond August 1993'
APSW-1 APSW-2 APSW-3 APSW-4
Water concentrations in pgll
VOCs
Acetone
SVOCs
Pentachlorophenol
PEST/PCBs
ND
1
ND
ND
16
ND
ND
ND
ND
ND
ND
ND
ND
Metals ....'.
Ba
Ca
Fe
Pb .
Mg
Mn
K
Na
Zn '
2.9-2.1
1920-2900
60.5-1250
2.5
2170-2230
29.6-1770
1170-2060
8560-8920
5.7-12.1
2.8-4.3
1930-2540
44
2130-2170
36.3-344
1170-1230
8370-8770
6.1
3
.1885
2195
45.1
1270
9025
2.6,
1850
2200
46
1256
8767
'Vol. H, HAZWRAP, Fig. 7-34.
DRAFTJune 13, 1996
103
-------
Table E-6-2. Ashumet Pond sediments, 3rd quarter results. (Volume H, HAZWRAP, 1995, Table 7-
4). ' ., . ' . '/ .
Ashumet Pond Sediments August 1993
APSD-1 APSD-2 APSD-3 APSD-4 APCB-1 APCB-2
Compounds
VOCs Otg/kg)
Tetra-chloroethane, '
1,1,2,2, Tetra-chloroethane
1,1,1, Trichloro-ethane
Toluene
Chlorobenzene
Acetone
2-Butanone (MEK)
Methylene Chloride
Carbon Disulfide
Ethylbenzene
7
*
280J
20J
100
22 ;
1J
'
ND
-
'
2J
2J
2J
ND
95000J/59000
' ; .
16000J/100000J
920J/1400J
15000/22000
870/ND
SVOCs Cug/kg)
Di-n-butylphthalate
B is-2-eithylhexylphthalate
Di-ethylphthalate
TIC (Benzoic Acid)
Pentachloro-phenol
Phenanthrene
Carbozole
Fluoranthene
Pyrene
Benzo(b)fluoranthene
Benzo(a)pyrene
. Indeno(l,2,3cd)Pyrene
Benzo(g,h)perylene
220J
170
570J
88J/ND
51J/75
54.
160J
820
51J
310J
53J
270J
55J
390
380
170J
150J
110J
88J
74J
493
<- -
!
860
57J
76J
290J
400
470
170J
150J
104
Wdquoit Bay Watershed Ecological Risk Assessment
-------
Table E-6-2. Ashumet Pond sediments, 3rd quarter results. (Volume n, HAZWRAP, 1995, Table 7-4)
(continued). ' '
Ashumet Pond Sediments August 1993
APSD-1 APSD-2 APSD-3 APSD-4 APCB-1 APCB-2
Pesticide/PCBs C"g/kg)
4,4'-DDT
ND
ND
Metals (rag/kg)
AI
As
Ba
Ca
Cu
Cr
Fe
Pfa
Mg
Mn
K
Na
V
Zn
1610
2.2
13
333
1660
19.4J
321
66
223
129
43.7
914/793
9.5/8.2
266/198
1250/117
2
12.8/8.7
213/223
72.8/68
115/76,
56.3/73
3.6/3.0
15.4/19
ND
ND
ND
-
8.6
1110
9.5
118
2.3
2.3 '
1860
2.7J
258
176
174
43.8
4.5
10.2
VOCs - Volatile Organic Compounds
SVOCs - Semivolatile Organic Compounds
PCBs - Polychlorinated Biphenyls
TIC - Tentatively Identified Compound
548
7.9
128
592
6J
109
56.9
69.4
60.7
12.4
397
1.8
67.4
732
139.
57
43.5
45.5
1680
1.1 ' .
13.9,
1170
12
7.4
4850
22.4J
773
58.2
369
85.5
12.9
'
.
ND - Non Detect
J - Estimated Value
DRAFTJune -13, 1996
105
-------
Table E-6-3. Chemical contaminants in Ashumet and Johns Ponds (Volume O, HAZWRAP, 1995,
Figure 7-36).
Johns Pond April 1993
JPSW-I JPSW-2 JPSW-3 JPSW-4
Water concentrations in /«g/l
voc
Methylene chloride
Carbon disulfide
SVOCs
Di-n-butylphthalate '
bis(2-chloroethyl) ether
Diethylphalate
PEST/PCBs
Metals
Fe v
Mn
Na
Zn
ND
ND
ND
'
48.9 ,
15.2
8910
4.3
ND
9 ,
2
ND
73.3 :
22.4
8780
5.5
ND
2 ' .
2
2
ND
48.9
13.5
8810
4.8
0.5
ND
ND
14.1
8840
4.3
Johns Pond August 1993 . .
JPSW-1 JPSW-2 JPSW-3 JPSW-4
Water concentrations in ngl\
yocs
SVOCs
Tributyl phosphate
PEST/PCBs
Metals
Al "
As
Ba
Ca ,
Fe
Mg
Mn . , .
K
Na
Zn
ND
16
ND
6.9-24.7
2840-3350
54.6-1240
2130-2160
36.5-1320
951-1100
8300-8630
38.9
ND
ND
ND
6.7-8
2840-3270
2150-2160
25.6
969-998
8440-8800
ND
ND
ND
6.9-11.5
2770-2800
24.5-159
2150-2200
29.2-631
995-1100
8410-8880
ND
ND '
ND
20.1
2.1
7
2874
2148
14.75
955
8924
106
Waquoit Bay Watershed Ecological Risk Assessment
-------
Table E-6-4. Johns Pond sediments 3rd quarter results. (Volume n, HAZWRAP, 1995,'Table 7-5).
.Johns Pond Sediments, August 1993 ''.."
. .. v ,-:>' -,,-.: . ,.-..;. :>. : :<-. -'..,;' ,.: . r . .
JPSD-l JPSD-2 JPSD-3 JPSD-* JPCB-1 JPCB-2
Compounds . .
VOCs fcg/kg)NDND
2-Butanone (MEK)
Toluene
Acetone
Carbon Bisulfide
Methylene Chloride
SVOCs fag/kg) '
JDi-n-butylphthalate
Bis-2-
TIC (Benzoic Acid)
PESTICIDE/PCBS
METALS mg/kg
Al
As
Ba
Ca
Cu
Cr
Fe
Pb
Mg
Mn
K
Na
V
Z
25J
5
490J
5J
130
160J
ND
5630J
32.9
925
10.1
3850J
24.2
989
147
520
315
11.3
34
3J
ND
ND
741J
3.8
167
1270J
5.2
318
17.2 .
112'
47.1
3.3 .
9.4
11J
470J
31J
110
130J
.130J
ND
7050J
1.9J
40.1
1120
7.1
10.9
5640J
26.6 .
1250
126
599
192
15.9
39
7J
50J
52J
ND
1630J
7.7
182
17.3
1540J
3.9
355
64.2
142
59.7
5.5
11.1
ND/ND
62J/46J
45J/ND
ND
409J/-347J
2.2/1.4
44.87-64.3
671J/530J
ND/0.46
162/127 .
11.4/7.1
147/39.8
59.9/37.4
7.6/4.1
38J
44
60J
54J -
ND
2070J
0.46J
10.3
328
3.8
2.5
1280J
7.5
192
30.2
104
84.6
3.9
21.1
Key;
VOCs - Volatile Organic Compounds
SVOCs - Semivolatile Organic Compounds
PCBs - Ploychlorinated Biphenyls
TIC - Tentatively Identified Compound
ND - Non Detect
J - Estimated Value
DRAFTJune 13, 1996
107
-------
Table E-7. Summary of histopathological examinations for brown bullhead catfish from Ash'umet and
Johns Ponds, Cape Cod, MA (Volume H, HAZWRAP, 1995, Table 7.17)
Pathology
Exterior Sores/Growths
Liver Cancer
Macrophage, Aggregates
Functional Liver Tissue
Ashumet Pond.
(frequency of occurrence).
47%
0.00
80% moderate/severe
81%
^^Pond':';-;^^:;'^';:;.:.,
(frequency of occurrence) xi
67%
2 individuals
90% moderate/severe
0.81
Eelgrass Disease, Pathogens include infectious agents of disease such as viruses; bacteria, fungi,
and protozoa. Disease is any impairment of the vital functions of an organism; it can be caused by
other organisms known as pathogens (biological stressors) or by abiotic factors (physical and
chemical stressors discussed above). Pathogens can be endemic or introduced. The severity, of a ,
disease is influenced by the susceptibility of the host, virulence of the pathogen, and environmental
factors that can affect the ability of the host to resist infection as well as the proliferation, of the
pathogen in the environment or in the host, Diseases caused by pathogens affect commercially
important finfish and shellfish species in freshwater and estuarine ecosystems, as well as the
organisms on which they depend for food, shelter, and other resources (Sindermann,, 1990; Couch
and Fournie, 1993). Outbreaks of disease can occur sporadically, although chronic infections can
produce sublethal adverse effects in some individuals of a population at all times. Biotic diseases
can also affect behavior, development, growth, reproduction, or survival of the population infected
by a particular pathogen, .as well as indirectly affecting dependent populations and producing a
cascade of effects hi an ecosystem.
Although some pathogen-induced diseases of finfishes, shellfishes, and other aquatic organisms
have been reported elsewhere in the Northeast and probably occur in Waquoit Bay watershed, and .
black-crowned night-herons that feed in the bay have been found with abdominal lesions of
unknown origin (WBNERR, 1993), the most significant biological stressor recognized in the
watershed is a disease affecting eelgrass. Eelgrass was at one time the dominant submerged aquatic
vegetation in coastal areas of the North Atlantic. In the 1930s the wasting disease, caused by a
slime mold (Labyrinthula) eradicated about 90 percent of the eelgrass meadows on both sides of the
Atlantic. The eelgrass recovered, but then declined again. In the 1980s, another outbreak of the
disease affected eelgrass beds in the United States (Short et al., 1988). After the 1930s outbreak,
many species characteristic of the eelgrass meadows disappeared, including the gastropod snails
Bittiuni alternatun and Miterella, the Atlantic brant (Branta bemical hrota), and the bay scallop
(Short et al., .1988; Short et al., 1992). Bay scallop larvae and juveniles attach to eelgrass blades to
effectively avoid predators (Pohleetal., 1991). '
The eelgrass wasting disease has been found in a 1989 survey only in the Hamblin Pond area of the
Waquoit Bay complex (Short et al., 1992). The marine slime mold is adapted to the more saline
waters of the lower reaches of coastal ponds. In the aftermath of the wasting disease, some
eelgrass survived in the less saline parts of estuaries. Today, these eelgrass beds are threatened by
their proximity to the coasts with their collateral load of nitrogen and suspended sediments (Short,
1988). The wasting disease might also act synergistically with stress from reduced light resulting in
decreased4 eelgrass growth.
108
Waquoit Bay, Watershed Ecological Risk Assessment
-------
Fisheries Harvesting. Harvesting of finfish and shellfish species by humans is another biological
stressor identified in the Waquoit Bay watershed. Removal of aquatic resources at rates faster than
the organisms can reproduce and replenish the populations results in reduced abundances and
limitations in distribution, as well as adverse effects on the species that prey on these commefcially-
or recreationally-important species. Overharvesting has been recognized as serious threat to the
stability of freshwater, estuarine, and marine ecosystems (reviewed hi Gulland, 1983).
Commercial fisheries can deplete stocks year-round, although fishing pressure is greatest hi
summer when weather conditions are best.
In the Waquoit Bay watershed, most of the finfish harvesting effort occurs offshore, focusing on
whiter flounder, summer flounder, tautogs, and Atlantic pollack. Adult whiter flounder can be
restricted in their offshore distribution range from certain estuaries, so that it is not clear that the
Southern New England, (SNE) stock is indeed-a distinct subpopulation of fish (biological stock as
opposed to economic stock). The same.situation might apply to adult tautogs. Summer flounder
are at the northern extension of their range hi the SNE area, so that this species has a lesser impact
in the offshore region from Waquoit Bay. Quantitative assessments provide evidence of regional
impacts resulting from fishing mortality and natural mortality (resulting from habitat degradation,
pollution effects, eutrophication, meteorological events, and long-term changes hi climate)..
Whiter flounder and summer flounder are part-tune estuarine residents mat are important
commercial species hi southern New England. Fishing mortality resulted hi a 55 percent decrease
hi annual survival for summer flounder and a 38 to 42 percent decrease for whiter flounder hi 1992
(NMFS/NEFSC/CUD, 1992). As a consequence of combined fishing and natural mortality, the
annual survival for summer flounder, is 27 percent and that for whiter flounder is 24 to 28 percent,
which implies that both species suffer from excess harvesting. Thus, regional commercial and
recreational fishing activities play an important role in their distribution and abundance hi Waquoit
Bay. The SNE stock biomass levels for summer flounder decreased dramatically from 1985 to
1991, and was dominated hi 1991 by fish aged two years and younger (adults are viewed as two
and older). The whiter flounder stock hi SNE decreased to record low levels between 1989-1991,
with a 1991 commercial catch of 4700 metric tons and a recreational catch of 1100 metric tons
(NMFS/NEFSC/CUD, 1992).
For the tautog, hi Southern New England state waters the maximum estimated fishing mortality
ranges from 0.15 to 0.33 (14 to 28 percent decrease hi annual.survival). The Massachusetts state
bottom trawl survey for Re'gion 1 (Buzzards Bay and Vineyard Sound) and Region 2 (Nantucket
Sound) has shown a decreased index of abundance from J982-1986 through 1992, even though a
common indicator of overfishing, reduction hi the average size of the adult tautog caught hi
Region 1, has not been detected (Caruso, 1993).
* ,
Recreational fishing of rainbow trout, brook trout, yellow perch and smallmouth bass within the
freshwater ponds systems is creating a demand on these resources and an increase hi local fishing
efforts could reduce these resident finfish populations.
Shellfishing (commercial and recreational) hi Waquoit Bay is regulated by the shellfish wardens hi
Falmouth and Mashpee; commercial harvest records extend back to 1965 hi Falmouth, and from
1976.through 1987 hi Mashpee (Table E-8). Town shellfish landings depend on shellfish seed set
or availability and fishing effort related inversely to shoreside employment opportunities
(MacKenzie, 1989). The quahog landings have been relatively stable during this period. jSoftshell
DRAFT-June 13, 1996 109
-------
landings increased, probably as a consequence of more effort directed toward this shellfishery.
Scallop landings, however, have been mixed due to the short-lived (two years) nature of this
species and variable recruitment. Adult quahogs are susceptible to overfishing because of their
slow growth and variable recruitment; the population in the bay is dominated by commercially
undersized clams (Funderburk et al., 1991). The slow growth rates might also contribute to
increased susceptibility to predation. It takes approximately two years for juvenile quahogs to
reach a minimum length of two inches in southern Massachusetts.
Table E-8. Shellfish Harvest by Year in Waquoit Bay, From Falmouth Commercial Harvest Records.
" v*v "). ^&& ""* " ff f '
" vs " . J&$$', V f A;
1976
1977
1978 '
1979
1980 .
1981
1982
1983
1986
1987
^^^tf*^'?5?
3274
3930
3292
3590
3985
3540
4650
4410
2750
3045
^Qj^^s^^i
2074
570
41477
7200
244
596
985
550
3150
2600
201
232
300 ,
950-
1625
1730
1680
1938
1275
'. 1819
sv&b-wS1 ''*,rt*>«*
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APPENDIX F: LAND USE MAPS FOR WAQUOIT BAY
WATERSHED
DRAFTJune 13, 1996 111
-------
-------
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g
I
g,
00
g
1
tvH
^1( ,
u
^
oo -
_
'I
53
cd
U
8
p
o
J-
o
g
ti
£
IM
o o "S "£
"3 _ '&
-------
-------
-------
-------
-------
-------
-------
-------
-------
-------
-------
-------
e laieg;or l
Crop Land
Pasture
..Forestland; ' ^ .
Fresh.later -let land
Mining
Open Land
'Par.tiqi.pation Recreation
Spectator.Recreation
later Based Recreation
Multi-Family Residential
High Density Residential;
Medium Dens i ty Res ident i al
Low Density Residential
Salt let land '....;
Coimierciai '
Industrial
Urban, Open and Public
Transportation .
faste Disposal
later
foody Perennial
Cranberry Bog.-
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-------
Land Use Change over Time (ha).
Land Use .
'1951
1971
1980
1985
1990
Agricultural Land - ."
Pasture ' ^
Forest .
Fresh Water .Wetlands
Mining .-
Open Lands
Outdoor RecreationParticipation
Outdoor RecreationSpectator
Outdoor RecreationWater. Based
Multi-Family Residential
Dense Residential
Medium Residential
Light - Residential,
.Salt' Water Wetlands ' . '
Commercial '_'.'
Industrial '
Open arid Public Urban Land ..
Urban Transportation
Waste Disposal
Open Water ..
Woody Perennials
Cranberry Bog1'
Golf Course
Marina
Total ;'
Total minus open water
358
140
3717
: 31
185
90
110
425
321
111
5493
5171
.38
.53
.88
.19
.97
.76
.21
,64
.71
.11
.39
.68
175
28
3421
74
' 20
177
0
39
1
122
261
118
4
2
17
580
0
324
25
68
24
0
5493
5168
.33
.86 '
.26
.80
.09
.94
.65
.70
.52
.23
.83 '
.55
.87
.54,
.94
.43
.92
.42
.30
.91
.92
.S3
.01
.59,
162
12
,3201
49
18
191
0
27
286
' 371
143
.1
12
591
324
21
' 51
25
5493
5169
.07
'.89
.53
.56
.79
.77
.22
-.14
.19
.56
.06
.46
,58
.98
,34
.58
.63
.18
.53
.19
117
28
3059
'so
23
171
' 6
. 3
29
, -10
. ' 34
343
398
J 129
: 11
1
203
437
2
354
' .!34
31
26
5539
5185
.27
.62
.65
.87
.50
.26
.38
.18
.43
,55
.2-6
.30
.36
. 47 : -
.84
.96
.03
.01
.42;
.48
.18
.71
.85
.58
-10
114
36
2'649
83
27
179
. 5
3
28
29
43
480
574
129
17'
3
224'
' 440
4
3 7.1
14
,4'1
46
2
5549
5178
.18
.96
.91
,05
.89
.52
.15
.18
.05
.64
.83
.40
.77
.10"
.22
.73
.34'
.40
.07
,67
.83.
.77
.21
.78
.86
.19
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Cape Cod,
Massachusetts
Pond Recharge Areas
A Snake Pond
B Ashurnet Pond
C Johns Pond
Drainage Sub-basins
1 Eel Pond
2 Childs River
3 Head of the Bay
4 Quashnet River
5 HamblinPond
6 Jehu Pond
7 Sage Lot Pond
Vineyard Sound
5 Kilometers
Scale 1:100.000 ,
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