EPA/620/R-96/004
September 1996
Assessment of the Ecological Condition of the
Delaware and Maryland Coastal Bays
J.C. Chaillou
S.B. Weisberg
Versar, Inc.
Columbia, MD 21045
RW. Kutz
T.E. DeMoss
U.S. Environmental Protection Agency
Annapolis, MD 21401
L. Mangiaracina
U.S. Environmental Protection Agency
Region III
Philadelphia, PA 19107
R, Magnien
Maryland Department of Natural Resources
Annapolis, MD 21401
R. Eskin
Maryland Department of the Environment
Baltimore, MD 21224
J. Maxted
Delaware Department of Natural Resources and Environmental Control
Dover, DE 19903
K. Price
College of Marine Sciences
University of Delaware
Lewes, DE 19958
J.K, Summers
U.S. Environmental Protection Agency
Gulf Breeze, FL 32561-5299
Printed on Recycled Paper
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FOREWORD
This report, entitled Assessment of the Ecological Condition of the Delaware and Maryland Coastal
Bays, was funded by the U.S. Environmental Protection Agency under Contract No. 68-DO-0093 to
Versar, Inc. . .
Data requests should be submitted to Dr. R. Kutz at the U.S. Environmental Protection Agency, Region
III, Annapolis, MD. •
Phone; (410) 573-6842
CONDITION OF DELAWARE AND MARYLAND BAYS Page ii
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TABLE OF CONTENTS
FOREWORD i
TABLE OF CONTENTS I
EXECUTIVE SUMMARY v
ACKNOWLEDGEMENTS vii
1.0 INTRODUCTION 1
1.1 THE COASTAL BAYS JOINT ASSESSMENT: BACKGROUND AND RATIONALE 1
1.2 OVERVIEW OF CBJA 2
1.3 PURPOSE AND ORGANIZATION OF THIS REPORT 3
2.0 METHODS 5
2.1 SAMPLING DESIGN '. . 5
2.2 SAMPLE COLLECTION .'. 6
2.2.1 Water Column 6
2.2.2 Sediment and Benthic Macroinvertebrates 8
2.3 SAMPLE PROCESSING METHODS 8
2.3.1 Water Chemistry 8
2.3.2 Benthic Macroinvertebrates 9
2.3.3 Silt-Clay Content 10
2.3.4 Benthic Chlorophyll 10
2.3.5 Sediment Chemistry 10
2.4 DATA ANALYSIS 10
3.0 PHYSICAL CHARACTERISTICS 16
3.1 BACKGROUND 16
3.2 MAJOR SUBSYSTEMS 16
3.2.1 Depth 16
3.2.2 Silt-Clay Content 16
3.2.3 Salinity 20
3.2.4 Temperature and pH 20
3.3 TARGET AREAS 20
3.3.1 Depth 20
3.3.2 Silt-Clay Content 20
3.3.3 Salinity 20
3.3.4 Temperature and pH 20
3.4 COMPARISON WITH PREVIOUS STUDIES 24
3.5 COMPARISON TO SURROUNDING SYSTEMS 24
4.0 WATER QUALITY 25
4.1 BACKGROUND 25
4.2 MAJOR SUBSYSTEMS 25
4.2.1 Measures of Algal Productivity 25
CONDITION OF DELAWARE AND MARYLAND BAYS Page in
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4.2.2 Dissolved Oxygen 26
4.2.3 Measures of Water Clarity 26
4.2.4 Nutrients 30
4.2.5 SAV Restoration Goals 30
4.3 TARGET AREAS 37
4.3.1 Measures of Algal Productivity 37
4.3.2 Dissolved Oxygen 37
4.3.3 Measures of Water Clarity . 37
4.3.4 Nutrients 37
4.3.5 SAV Restoration Goals 42
4.4 COMPARISON WITH PREVIOUS STUDIES 42
4.5 COMPARISON TO SURROUNDING SYSTEMS 46
5.0 SEDIMENT CONTAMINANTS . 48
5.1 INTRODUCTION ....48
5.2 CONDITION OF THE COASTAL BAYS .....L..53
5.3 CONDITION OF DEAD-END CANALS 53
5.4 COMPARISON TO PREVIOUS STUDIES 54
5.5 COMPARISON TO SURROUNDING SYSTEMS 54
6.0 BENTHIC MACROINVERTEBRATES , i..56
6.1 BACKGROUND 56
6.2 MAJOR SUBSYSTEMS .....56
6.2.1 Abundance and Biomass 56
6.2.2 Species Richness and Diversity 57
6.2.3 EMAP Benthic Index ; 57
6.3 TARGET AREAS 5.7
6.3.1 Abundance and Biomass .-. 57
6.3.2 Species Richness 62
6.4 COMPARISON WITH PREVIOUS STUDIES ... 62
6.5 COMPARISON TO SURROUNDING SYSTEMS... .....67
7.0 CONCLUSIONS 68
8.0 REFERENCES , 71
APPENDIX A A-l
APPENDIX B B-l
APPENDIX C C-l
APPENDIX D .. ...D-l
APPENDIX E : E-l
CONDITION OF DELAWARE AND MARYLAND BAYS page iv
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EXECUTIVE SUMMARY
The coastal bays of Delaware and Maryland are an important ecological and economic resource whose
physical characteristics and location make them particularly vulnerable to the effects of pollutants. This
project was undertaken as a collaborative effort between state and federal agencies to assess the
ecological condition of this system and fill a data void identified in previous characterization studies. Two
hundred sites were sampled in the summer of 1993 using a probability-based sampling design that was
stratified to allow assessments of the coastal bays as a whole, each of four major subsystems within
coastal bays (Rehoboth Bay, Indian River Bay, Assawoman Bay, and Chincoteague Bay) and four target
areas of special interest to resource managers (upper Indian River, St. Martin River, Trappe Creek, and
dead-end canals). Measures of biological response, sediment contaminants, and eutrophication were
collected at each site using the same sampling methodologies and quality assurance/quality control
procedures used by EPA's Environmental Monitoring and Assessment Program (EMAP). As an additional
part of the study, trends in fish communities structure were assessed by collecting monthly beach seine
and trawl measurements during the summer at about 70 sites where historic measurements of fish
communities have been made.
Major portions of the coastal bays were found to have degraded environmental conditions. Twenty-eight
percent of the area in the coastal bays had degraded benthic communities, as measured by EMAP's
benthic index. More than 75% of the area in the coastal bays failed the Chesapeake Bay Program's
Submerged Aquatic Vegetation (SAV) restoration goals, which are a combination of measures that
integrate nutrient, chlorophyll, and water clarity parameters. Most areas failed numerous SAV goal
attributes. Sixty-eight percent of the area in the coastal bays had at least one sediment contaminant with
concentrations exceeding published guidelines for protection of benthic organisms. Further study is needed
to assess whether the biological effects observed were the direct result of contamination.
Within the coastal bays, Chincoteague Bay was in the best condition of the four major subsystems, while
Indian River was the worst. Only 11% of the area in Chincoteague Bay had degraded benthos compared
to 77% in Indian River. Less than 10% of the area in Indian River met the Chesapeake Bay SAV
Restoration Goals. In comparison, almost 45% of the area in Chincoteague Bay met the Chesapeake Bay
Program's SAV restoration goals, a figure which increased to almost 85% when only the most
controllable components of the goals (nutrient and chlorophyll) were considered.
CONDITION OF DELA WARE AND MARYLAND BAYS Page v
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All of the target areas of special management interest were in poorer condition than the remainder of the
coastal bays, with dead-end canals having the poorest condition. Chemical contaminants exceeded
published guideline values in 91% of the area of the dead-end canals, and 57% of their area had dissolved
oxygen concentrations less than the state standard of 5 ppm. Dead-end canals also were biologically
depauperate, averaging only 4 benthic species per sample compared to 26 species per sample in the
remaining portions of the coastal bays.
The consistency of the sampling design and methodologies between our study and EMAP allows unbiased
comparison of conditions in the coastal bays with that in other major estuarine systems in EPA Region III
that are sampled by EMAP. Based on comparison to EMAP data collected between 1990 and 1993, the
coastal bays were found to have a similar or higher frequency of degraded benthic communities than in
Chesapeake or Delaware Bays. Twenty-eight percent of the area in the coastal bays had degraded
benthic communities as measured by EMAP's benthic index, which was significantly greater than the 16%
EMAP estimated for Delaware Bay using the same methods and same index, and statistically
indistinguishable from the 26% estimated for Chesapeake Bay. The coastal bays also had a prevalence of
chemical contamination in the sediments that was higher than in either Chesapeake Bay or Delaware Bay.
Sixty-eight percent of the area in the coastal bays exceeded published guideline values for at least one
contaminant compared to 46% for Chesapeake Bay and 34% for Delaware Bay. While the percent of
area having these concerns is higher in the coastal bays, the absolute amount of area having these
concerns is greater in the Delaware and Chesapeake Bays because of their larger size.
The fish community structure in Maryland's coastal bays was found to have remained relatively
unchanged during the past twenty years while that of similar systems in Delaware have changed
substantially. Fish communities of the Maryland coastal bays are dominated by Atlantic silversides. bay
anchovy, Atlantic menhaden, and spot, which is similar to the community structure measured in the
Delaware coastal bays 35 years ago. The fish fauna in Delaware's coastal bays has shifted toward species
of the Family Cyprinodontidae (e.g., killifish and sheepshead minnow) which are more tolerant to low
oxygen stress, and salinity and temperature extremes.
CONDITION OF DELAWARE AND MARYLAND BAYS page vi
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ACKNOWLEDGEMENTS
This data summary is the culmination of the efforts of many people from multiple organizations. The
authors would like to acknowledge the efforts of the members of field collection, laboratory analysis, and
data analysis teams whose hard work and dedication made this program a success. . .,. .
The 1993 field sampling effort was a cooperative effort of numerous individuals. We would especially like
to thank Ben Anderson, Ellen Dickey, and John Maxted of Delaware Department of Natural Resources
and Environmental Control; Kelly Cox, Laura Fabian, and Jenny Gillis of the Maryland Department of the
Environment; and Randy Hochberg and Fred Kelley of Versar for their dedication to completing the field
effort We are also grateful to Natalie Wagner of EPA for administrative tracking of field data and sample
shipments. . , : .
Researchers from several institutions contributed significantly to this effort through the laboratory analysis
of samples. We wish to thank Lisa Scott of Versar and Nancy Mountford of Cove Corporation for
processing the benthic invertebrate samples; Pete Sampou, Lois Lane, and Sara Rhodes of Horn Point
Environmental Laboratory for analyzing the water quality samples; Nate Malof of EPA who oversaw the
analysis of sediment contaminants samples; and Richard Geider and Lee Karrh of the University of
Delaware who performed the benthic chlorophyll analysis.
We are grateful to Mike Gaughan, Ananda Ranasinghe, and Jon Volstad for assistance in the data
analysis, Thuzar Myint and Don Strebel for developing GIS maps, and Emily Rzemien and Renee
Conner for providing graphic illustrations. We thank Tom Parham for his significant technical and
logistical support during several phases of the study. We also thank Carol DeLisle for editorial help, and
Gail Lucas and Lois Haseltine for document production.
We would also like to acknowledge the individual members of the Delaware/Maryland Coastal Bays
Joint Assessment Steering Committee, whose dedication and perseverance were crucial to the
implementation and success of this program:
Frederick W. Kutz U.S. Environmental Protection Agency, Region III
Tom DeMoss
Leonard Mangiaracina
Edward Ambrogio
CONDITION OF DELAWARE AND MARYLAND BAYS Page vii
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John Maxted
Bennett Anderson
Richard Eskin
Robert Magnien
Ronald J. Klauda
James R Casey
Cecelia C. Linder
Steven B, Doctor
Kent Price
Delaware Department of Natural Resources and Environmental Control
Maryland Department of the Environment
Maryland Department of Natural Resources
University of Delaware, Delaware Inland Bays Estuary Program
CONDITION OF DELAWARE AND MARYLAND BAYS
Page viii
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1.0 INTRODUCTION
1.1 THE COASTAL BAYS JOINT
ASSESSMENT: BACKGROUND
AND RATIONALE
The coastal bays formed by the barrier islands of
Maryland and Delaware are important ecological
and economic resources. The coastal bays are
spawning and nursery areas for more than 100
species of fish, almost half of which are of
commercial or recreational value. The bays are
surrounded by an extensive network of tidal
wetlands that contributes to and sustains this
nursery and many other functions. The coastal
bays also provide important habitat for migratory
birds; the bays are part of the Atlantic fly way,
one of four major migratory routes in the United
States. For these reasons, both the coastal bays
of Delaware and Maryland are included in the
National Estuary Program.
The coastal bays are also an important economic
resource. More than 10 million people visit the
Delmarva Peninsula annually. The primary
recreational attractions of the region are boating,
swimming, and fishing, with more than a
half-million user-days of recreational fishing
each year (Seagraves 1985). The coastal bays
also support commercial fisheries for hard
clams, blue crabs, sea trout, and several other
species of fish. The total economic return from
recreational and commercial activities associated
with the coastal bays is estimated to exceed 3
billion dollars, and the bays support almost
50,000jobs.
The physical characteristics and location of the
coastal bays make them particularly vulnerable
to the effects of pollutants. The bays are mostly
land-locked and have few outlets to the ocean.
This, combined with a relatively limited volume
of freshwater inflow, results in a low flushing
rate (Pritchard 1960), and makes them
susceptible to concentration of pollutants (Quinn
et al. 1989). Water quality data suggest that
several tidal creeks supplying the coastal bay's
limited freshwater inflow are eutrophied (ANSP
1988), largely as a result of nutrient enrichment
from surrounding agricultural lands (Ritter
1986), thereby enhancing this concern. Steady
population increases in the watershed add to the
future concerns for this resource; an increase of
almost 20% by the year 2000 is expected for the
Maryland portion alone (Andriot 1980).
A first step in developing management strategies
for these systems is to characterize their present
condition and describe how it has changed over
time. Two recent efforts have attempted to
characterize the condition of the coastal bays for
that purpose (Boynton et al. 1993, Weston
1993), but both of these assessments noted that
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 1
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the amount of data available for the system was
limited. The available data were generally
collected more than a decade ago and usually
represented a limited number of collection sites
confined to areas perceived to have pollution
problems. The system-wide information
necessary to characterize the spatial extent of
any problems has never been collected.
An important part of such an assessment is
characterizing biological responses to
environmental problems, since protecting these
resources is the focus of management actions
and biological data are particularly lacking in
the coastal bays. The most comprehensive data
for characterizing benthic invertebrate condition
of the coastal bays comes from a 20-year-old
survey of a single system (Maurer 1977) and
that survey was used almost exclusively to
describe species distributions, not to evaluate the
ecological condition of the bays. Recent fish
surveys are available for Maryland's coastal
bays (Casey et al. 1993), but the last
comprehensive survey of Delaware's coastal
bays was conducted almost a quarter-century
ago (Derickson and Price 1973).
1.2 OVERVIEW OF CBJA
The Coastal Bays Joint Assessment (CBJA) is a
collaborative State and Federal effort to
characterize the condition of the coastal bays of
Delaware and Maryland and to fill the void
identified in the previous characterization
efforts. The CBJA has three major objectives:
(1) to assess the current ecological condition of
the coastal bays of Delaware and Maryland;
(2) to compare the current condition of the bays
with their historical condition; and
(3) to evaluate indicators and sampling design
elements that can be used to direct future
monitoring activities in the system.
The participants in the CBJA are the Delaware
Department of Natural Resources and
Environmental Control (DNREC), the Maryland
Department of the Environment (MDE), the
Maryland Department of Natural Resources
(MDNR), EPA Region HI, the Delaware Inland
Bays Estuary Program (DfflEP), and EPA's
Office of Research and Development. The
CBJA was initiated as a multi-state effort with
the recognition that the stresses on these
systems, and thus the management actions
necessary for their protection, are similar across
state boundaries. The CBJA focuses on
assessing condition of the coastal bays as a
whole, for each of four major subsystems within
the coastal bays (Rehoboth Bay, Indian River
Bay, Assawoman Bay, and Chincoteague Bay)
and four areas of special concern to resource
managers (upper Indian River, St. Martin River,
Trappe Creek, and dead-end canals).
In 1993, the CBJA initiated a comprehensive
field survey of the coastal bays in which data
were collected at 200 sites. The data collection
approaches used in the survey borrowed heavily
from methodologies developed by EPA's
Environmental Monitoring and Assessment
Program (Weisberg et al. 1993) and were
predicated on three general principles. First,
data were collected using a probability-based
sampling design. A probability-based sampling
design ensures .unbiased estimation of condition,
which is not possible when sampling sites are
preselected by the investigator, and ensures that
all areas within the system are potentially
subject to sampling. The probability based
sampling design also allows calculation of
confidence intervals around estimates of
CONDITION OF DELAWARE AND MARYLAND BAYS
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condition. Confidence intervals provide
managers with full knowledge of the strength or
weakness of the data upon which their decisions
will be based. Another advantage of the
probability-based sampling design is that it
allows investigators to estimate the actual area
(i.e., number of acres) throughout the system in
which ecological conditions differ from
reference areas. This emphasis on estimating
areal extent is a departure from traditional'
approaches to environmental monitoring, which
generally estimate the average condition.
Second, the survey collocated measurements of
pollution exposure with measurements of
biological response, enabling examination of
associations between degraded ecological
condition and particular environmental stresses.
Although associations do not conclusively
identify the causes of degradation, associations
are valuable for establishing priorities for more
specific research and could contribute to
developing the most efficient regional strategies
for protecting or improving the environment by
identifying the predominant types of stress on
the system.
Third, a common set of indicators, sampling
methodologies, and QA protocols were used
across state boundaries. The probability-based
sampling design provides a framework for
integrating data into a comprehensive regional
assessment; however, the validity of such an
assessment depends on ensuring that all the data
that contribute to it are comparable.
1.3 PURPOSE AND ORGANIZATION
OFTHIS REPORT
This report addresses the first objective of the
CBJA. It summarizes the data collected during
a 1993 sampling survey and provides a
preliminary assessment of the current ecological
condition of the coastal bays. Intended future
analyses of the CBJA include an examination of
trends in the condition of the bays using historical
data, an effort to associate the ecological
condition of the major bays and areas of special
concern with particular patterns of land use, and
an evaluation of the utility of EMAP approaches
within the coastal bays.
This report includes six chapters: Methods -
Chapter 2, chapters describing each of four
general groups of indicators (i.e., Physical
Characteristics - Chapter 3, Water Quality -
Chapter 4, Sediment Contaminants - Chapter 5,
Benthos - Chapter 6), and Conclusions - Chapter
7. Chapters 3 through 6 include tables of the
average values of the respective indicators in the
four major subsystems and the areas of special
concern, figures showing the percent of area
within the major subsystems and special target
areas that exceeds or falls below a generally
accepted threshold value (i.e., percent
"degraded" area) for selected indicators, and
maps showing the distribution of degraded sites
for selected indicators. These chapters also
compare the preliminary conclusions of the
CBJA with the results of other recent
characterizations of the coastal bays and with
assessments of other estuaries within EPA
Region in. These comparisons help to put the
CBJA results into regional perspective. The
report also includes three appendices: Appendix
A describes the methods and results of a fish
sampling effort that was conducted as an
ancillary part of the present study. The fish data
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 3
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were placed in an appendix because they were
collected using a different sampling design than
what was used for the rest of the project, and
because the purpose of the fish analysis was
different from the rest of the report. Fish
analyses focus on description of trends rather
than an estimation of current status. Appendix
B provides average concentrations for all
sediment contaminants measured in the survey;
Appendix C provides a species list of benthic
macroinvertebrates collected in the coastal bays
during 1993; Appendix D provides the
minimum, maximum, median and quartile
values of all attributes measured in the present
study; Appendix E provides a data summary for
a benthic survey of Turville Creek which was
conducted as an ancillary part of this study.
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2.0 METHODS
2.1 SAMPLING DESIGN
Sampling sites were selected using a stratified
random sampling design in which the coastal
bays were stratified into several subsystems for
which independent estimates of condition were
desired:
• upper Indian River
• Trappe Creek/Newport Bay
• St. Martin River
• dead-end canals throughout the coastal
bays
• all remaining areas within Maryland's
coastal bays
• all remaining areas within Delaware's
coastal bays
The upper Indian River, Trappe Creek, and St.
Martin River were defined as sampling strata
because resource managers expressed particular
concern about these areas. Water quality data
suggest that each of these tidal creeks is subject
to excessive nutrient enrichment, algal blooms,
and low concentrations of dissolved oxygen.
These creeks are also believed to transmit large
nutrient loads (from agricultural runoff)
downstream, contributing to eutrophication
throughout the coastal bays (Boynton et al.
1993).
Dead-end canals were defined as a stratum
because of their high potential for impact based
on their physical characteristics and their
proximity to a variety of contaminant sources
(Brenum 1976). These dredged canal systems
can form the aquatic equivalent of streets in
development parcels; they already encompass
105 linear miles and almost 4% of the surface
area of Delaware's inland bays. In general,
these systems are constructed as dead-end
systems with little or no freshwater inflows for
flushing. They are often dredged to a depth
greater than the surrounding waters, leaving a
ledge that further inhibits exchange with nearby
waters and leads to stagnant water in the canals.
The placement of these systems in relatively
high density residential areas increases the
potential for contaminant input. Much of the
modified land-use in dredged canal systems
extends to the bulkheaded water's edge,
providing a ready source of unfiltered runoff of
lawn-care and structural pest control products.
In many cases, the bulkhead and dock systems
in these canal systems are built from treated
lumber containing chromium, copper, and arsenic,
providing another source of contaminants.
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Page 5
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Two-hundred sites were sampled, 25 in each of
the first 4 sampling strata and 50 in each of the
last 2 (Figure 2-1). Sites for all strata except
canals were selected by using a two stage
process. First, the EMAP hexagonal grid
(Overton et al. 1990) was enhanced for the
coastal bays study area and the appropriate
number of grid cells was selected randomly for
each stratum. In the second stage, a random site
from within these cells was selected. Sites in the
dead-end canals were selected by developing a
list frame (of all existing canals), randomly
selecting 25 canals from that list, and then
randomly selecting a site within each canal.
All sampling was conducted between July 12 and
September 30,1993. Sampling was limited to a
single index period because available resources
were insufficient to sample in all seasons. Late
summer is the time during which environmental
stress on estuarine systems in the mid-Atlantic
region is expected to be greatest owing to high
temperatures and low dilution flows (Holland
1990). The sampling period coincided with the
period during which EMAP samples estuaries of
the mid-Atlantic region; therefore, data collected
in the coastal bays annually for EMAP can be
incorporated into estimates of ecological
condition generated from CBJA data and CBJA
data can contribute to continuing development
and evaluation of EMAP indicators.
2.2 SAMPLE COLLECTION
Samples were collected during daylight hours
from a 21-ft Privateer equipped with an electric
winch with a 12-ft boom. Sampling sites were
located using a Global Positioning System (GPS)
receiver. Dead reckoning was used to locate
sites when signal interference or equipment
malfunction prevented reliable performance of
the GPS receiver. Obvious landmarks, channel
markers, and other fixed structures were noted
to identify the site location whenever dead
reckoning was used.
2.2.1 Water Column
Temperature, dissolved oxygen, pH, conductivity,
and salinity were measured at each site using a
Hydrolab Surveyor II. The number of depths for
which water quality measurements were
collected depended upon the bottom depth (Table
2-1). Water clarity was measured using a 20-cm
Secchi disk. The presence of floating debris
within 50 m of the boat was noted. Debris was
categorized as paper, plastic, cans, bottles,
medical waste, or other.
Water samples were collected for analysis of
nitrogen, phosphorus and carbon species, total
suspended solids (TSS), turbidity; and *
chlorophyll a. A 250-mI sample bottle was
. deployed 0.5 m below the surface, rinsed three
times with ambient water, filled, capped, and
stored at 4° C for total suspended solids analysis.
The procedure was repeated with a 125-ml
bottle for measuring turbidity and a 1-gallon
bottle for nutrients. Three filiations were
performed for each nutrient parameter using
measured aliquots from the same one-gallon
sample. The volume of filtered sample varied
according to the relative turbidity at a site; high
turbidity caused low filtering volumes. A 47-mm
diameter GF/F filter was used for total
paniculate phosphorus analysis; a 25-mm GF/F
filter was used for chlorophyll a analysis; and an
ashed, 25-mm GF/F filter was used for
particulate carbon and nitrogen analysis. Each
filter was removed from the vacuum filtration
apparatus using forceps, wrapped in aluminum
foil, placed in a small zip-lock bag, and frozen on
CONDITION OF DELAWARE AND MARYLAND BAYS
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Dead-end Canals
Other Sampling Sites
Atlantic Ocean
Figure 2-1. Location of sampling sites in the Delaware/Maryland coastal bays.
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Table 2-1. Criteria for in situ water quality
w
M
Bottom Depth (m)
£l
Ito2
2 to 3.3
>3.3
Measured 0.5 m below the surface.
Measured 0.5 m above the bottom.
measurements
Water Quality Measurements
Surf ace (a)
Surface, bottom
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2.3.2 Benthic Macroinvertebrates
Species composition, abundance, and biomass
of benthos, and silt-clay content were
determined using methods outlined in the
EMAP Near Coastal Laboratory Methods
Manual (Klemm et al. 1993) and updated in
Frithsen et al. (1994). The macrobenthos were
identified to the lowest practical taxonomic
category and counted. Identified organisms
were placed into predetermined biomass groups
and formaldehyde dry weight was determined.
Bivalves and gastropods were acidified prior to
weighing to remove inorganic shell material. To
standardize the biomass measurements, all
samples were preserved in a 10% solution of
buffered formaldehyde for at least two months
before measuring biomass.
Table 2-2. Analytical methods for water column chemistry.
Analyte
Method
References
Chlorophyll a Phaeophytin
Nitrate and Nitrite
Ammonium
Total Dissolved Nitrogen
Orthophosphate
Total Dissolved Phosphorous
Total Paniculate Nitrogen
Total Paniculate Phosphorous
Total Paniculate Carbon
Dissolved Organic Carbon
Total Suspended Solids
Turbidity
Spectrophotometric; Trichromatic
Calorimetric; cadmium reduction
Calorimetric; automated phenate
Calorimetric; persulfate oxidation
Calorimetric; automated ascorbic acid
Calorimetric; persulfate digestion and
automated ascorbic acid
/
Oxidative combustion
Calorimetric; persulfate digestion
Oxidative Combustion
Persulfate Digestion
Gravimetric
Nephelometer
APHA (1981)
EPA Method 353.2
EPA Method 350.1
D'Elia et al. (1977)
EPA Method 365.1
EPA Method 365.1
Leeman Labs (1988)
Aspillaetal. (1976)
Leeman Labs (1988)
Menzel and Vaccaro 1964)
APHA (1981)
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2.3.3 Silt-Clay Content
2.4 DATAANALYSIS
Sediment samples were processed to determine
silt-clay content according to EMAP procedures
described in Klemm et al. 1993. Sediment
samples were sieved through a 63-jim mesh
sieve. The filtrate and the fraction remaining on
the sieve were dried at 60°C and weighed to,
calculate the proportion of silts and clays in the
sample.
2.3.4 Benthic Chlorophyll
Sediment samples were processed to determine
benthic chlorophyll concentrations. Sample'-.
aliquots were suspended in 90% acetone, v. *
extracted overnight at -2Q°C, resuspended, arid
the supernatant was collected. Each sample, was
extracted three times and the supernatants were
combined. The benthic chlorophyll concentration
of the supernatant was determined by two
different methods: (1) high-performance liquid
chromatography described by Heukelem et al.
(1992) and (2) the fluoromenic method described
in Parsons et al. (1984). , :
2.3.5 Sediment Chemistry • ..:;•;
Sediments were analyzed for the NOAA "..
National Status and Trends suite of .- ".
contaminants (Table 2-3) using standard : V
analytical methods (Table 2-4). Due to cost
constraints, only a random subset of 11 samples
from the dead-end canals and 10 samples from
the remaining coastal bays were processed in-the
laboratory. Data from non-canal areas were;,-" .,
supplemented with 14 samples recently "" • ,
collected by EMAP using a compatible sampling
design and identical field and laboratory methods.
For reporting purposes, the study area was
post-stratified into the following subpopulations:
, Rehoboth Bay, Indian River (including upper
Indian River), Assawoman Bay (including St.
Martin River), and Chincoteague Bay (Figure •
2-2). Boundaries of the four special target areas
.(i.e., upper Indian River, St. Martin River, Trappe
Creek/Newport Bay, and dead-end canals) were
riot changed. Dead-end canals were evaluated
as a separate subpopulation arid were riot
included in calculations for the remaining study
area.
The condition of each of these areas was
assessed in two ways: the mean condition and
the percent of area exceeding threshold values
for selected parameters. Since the sampling
sites within each stratum (except the dead-end
.canals) were selected with equal inclusion
probabilities, the mean parameter values (eq. 1) •
for a stratum, h, and its variance (eq. 2) were
calculated as:
(EQ.1).
where
yM is the variable of interest (e.g., concentration
of phosphorus), and nH is the number of samples
collected from stratum h.
The stratified mean value for£ strata with
combined area A is given by
(EQ.2)
CONDITION OFDELA WARE AND MARYLAND BA YS
Page 10
-------
Table 2-3. Analytes for CBJA sediment samples.
Polyaromatic Hydrocarbons (PAHs)
Acenaphthene
Fluoranthene
Pyrene
Benzo(e)pyrene
1-methylnaphthalene
Benzo(g,h,i)perylene
2,6-dimethylnaphthalene Perylene
Phenanthrene Benz(a)anthracene
Benzo(a)pyrene Ideno(l,2,3-c,d)pyrene
2-methylnaphthalene Acenaphthylene
Benzo(k)fiuofanthene Chrysene
Dibenz(a,b)anthracene Naphthalene
Anthracene
Fluorene .
Benzo(b)flupranthene
Biphenyl
1 -methylphenanthrene
2,3,5-Trimethylnaphthalene
DDT and its metabolites Chlorinated pesticides other than DDT
o,p'-DDD
p,p'-DDD
o,p'-DDE
Major El
Aluminum
Iron
Manganese
p,p'-DDE AW™
o,p'-DDT Hexachlorobenzene
p.p'-DDT Dieldrin
ements
Heptachlor epoxide Alpha-Chlordane
Trans-Nonachlor Lindane gamma-BHC)
Mirex Heptachlor
. Trace Elements
Antimony Arsenic Cadmium Chromium
Copper Selenium Lead Silver
Mercury Tin
Nickel Zinc
18 PCB Congeners:
No.
8
18
28
44
52
66
101
105
118
128
138
153
170
180
187
195
206
209
Compound Name
2,4'-dichlorobiphenyl
2,2,5- Irichlorobiphenyl
2,4,4'-trichlorobiphenyl
2.2'.3,5'-tetrachlorobiphenyI
2,2',5,5'-tetrachlorobiphenyl
23',4,4'-tctrachlorobiphenyl
2^',4,5,5'-pentachlorobiphenyl
2,3,3',4,4'-pentachlorobiphenyI
2,3',4,4'.5-pentachlorobiphenyl
2,2',3,3',4,4'-hexachlorobiphenyl
2,31.3.4.41,5-hexachk>robiphenyl
2,2',3,4,4',5l-hexachlorobiphenyl
2,2',4,4',S,5'-hexachlorobiphenyl
2,2',3,3',4,4',5-heptachlorobiphenyl
2^'3,4,4'33'-heptachlorobiphenyl
2,2',3,3',4,4',5,6-octachlorobiphenyl
2,2',3,3',4,4',53',6-nonachlorobiphenyl
decachlorobiphenyl
Other measurements
Tributyltln
Acid volatile sulfides Total organic carbon
CONDITION OF DELA WARE AND MARYLAND BA YS
Page 11
-------
1 1
Table 2-4. Analytical methods used for determination of chemical contaminant
concentrations in sediments
Compound(s)
Inorganics:
Ag, Al, Cr, Cu, Fe, Mn, Ni, Pb, Zn
As, Cd, Sb, Se, Sn
Hg
Organics:
Extraction/Cleanup
PAH measurement
PCB/pesticide
Method
Total digestion using HF/HNO3 (open vessel hot
plate) followed by Inductively coupled plasma-
atomic emission spectrometry (ICP-AES) analysis.
Microwave digestion using HNO3/HCI followed by
graphite furnace atomic absorption (GFAA)
analysis.
Cold vapor atomic absorption spectrometry
Soxhlet extraction, extract drying using sodium
sulfate, extract concentration using Kuderna-Danish
apparatus, removal of elemental sulfur with activated
copper, removal of organic interferents with GPC
and/or alumina.
Gas chromatography /electron
spectrometry (GC/MS)
Gas chromatography /electron capture detection (GC/
BCD) with second column confirmation
where the weighting factors, Wh = Ah/A, ensure
that each stratum h is weighted by its fraction of
the combined area for all L strata. An estimator
for the variance of the stratified mean (3) is
(EQ.3)
Strata were combined following Holt and Smith
(1979). Confidence intervals were calculated as
1.64 times the standard error, where the standard
error is the square root of the variance
(estimated by eq. 4). Statistical differences
between populations of interest were defined on
CONDITION OFDELA WARE AND MARYLAND BA YS
Page 12
-------
the basis of non-overlapping confidence
intervals.
where
h--
(EQ.4)
The samples from the dead-end canals were
treated as a cluster sample, in which the canals
formed clusters (areas) of unequal size. Mean
parameter values were calculated as
area-weighted means:
where
(BQJ)
q is the area-weighted mean
Cj is the area of canal i,
C is the combined area of all the canals sampled,
y, is the variable of interest (e.g., concentration
of phosphorus), and
n is the number of canals sampled.
The standard error was calculated using the
jackknife estimator (Cochran 1977, Efron and
Gong 1983):
(EQ.6)
(EQ.7)
is the weighted mean value deleting they'th canal
and
(EQ.8)
is the jackknife estimate of the mean y for the n
canals.
Estimates of percent of area exceeding selected
thresholds (e.g., dissolved oxygen concentration
less than 5 ppm) was calculated as p — Bin,
where B is number of samples exceeding the
threshold and n is the total number of samples in
the stratum. For strata with equal inclusion
probability, the exact confidence intervals for/?
were estimated from the binomial distribution
using the formula of Hollander and Wolfe (1973).
The exact confidence intervals could not be
obtained directly from the binomial distribution
for stratified random sampling or for clustered
sampling (canals). Since these sample sizes are
large, the confidence interval was calculated
using the normal approximation to the binomial.
For a combination of strata, the 90% confidence
interval of stratified estimates of proportions*/^,
was estimated as
ft,
|I«
(EQ.9)
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 13
-------
where
Pa(EQ.10)
(EQ.ll)
The formulas for estimating means and
variances for canals also were used to estimate
the percentage of area in the canals with_y
values that fell into some defined class. An
indicator variable, I,, was assigned the value if
the value of y, fell in a specified class, and 0
otherwise. The sample mean and variance of I;
is an estimate of the proportion of area in the
canals that has y values within the specified
class.
CONDITION OFDELA WARE AND MARYLAND BA YS page 14
-------
Legend
§H Mq|or Subsystem
Target Area
Mantle Ocean
38'3S
38-SWl
38'1S"
Figure 2-2. Boundaries of post-stratified subpopulations which were used in the study.
CONDITION OF DELA WARE AND MARYLAND BA YS
Page 15
-------
3.0 PHYSICAL CHARACTERISTICS
3.1 BACKGROUND
Measurements of physical characteristics
provide basic information about the natural
environment. Knowledge of the physical context
in which biological and chemical data are
collected is important for interpreting results
accurately because physical characteristics of
the environment determine the distribution and
species composition of estuarine communities,
particularly assemblages of benthic
macroinvertebrates. Salinity, sediment type, and
depth are all important influences on benthic
assemblages (Snelgrove and Butman 1994,
Holland et al. 1989). Sediment grain size also
affects the accumulation of contaminants in
sediments. Fine-grained sediments generally are
more susceptible to accumulating contaminates
than sands because of the greater surface area
of fine particles (Rhoads 1974; Plumb 1981).
Depth, silt-clay content of the sediment, bottom
salinity, temperature, and pH were measured to
describe the physical conditions at sites in the
coastal bays. Sediment type was defined
according to silt-clay content (fraction less than
63(i); classifications were the same as those
used for EMAP. Biologically meaningful salinity
classes were defined according to a modified
Venice System (Symposium on the Classification
of Brackish Waters 1958).
3.2 MAJOR SUBSYSTEMS
3.2.1 Depth
The coastal bays of Delaware and Maryland are
shallow systems with an average depth of 1.5 m
(Table 3-1). Depth exceeded 3 m at only 3 of
200 sampling sites. Average depth among the
four major subsystems was not significantly
different The amount of area shallower than
0.6 m may have been underestimated because
this was the minimum depth accessible for
sampling; however, less than 5% of the area in
each major system was unsampleable because of
insufficient depth.
3.2.2 Silt-Clay Content
The coastal bays had a diverse bottom habitat
including broad areas of mud, sand, and mixed
substrates (Figure 3-1). Sand was a more
predominant substrate than mud and accounted
for more than 40% of the study area. Muddy
sediments were less prevalent, accounting for
less than 20% of the area (Figure 3-2). The
distribution of mud, sand, and mixed substrates
was similar among Rehoboth, Assawoman, and
Chincoteague bays. The average silt-clay
content of Indian River Bay was significantly
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 16
-------
I
to
>a
§
Table 3-1. Area-weighted means of physical parameters (90% confidence intervals).
Parameter
Depth
Silt-Cky
Content (%)
Salinity
temperature CC)
pH
Entire
Study
Area
1.5
± 0.1
40
± 5
30.6
± 0.4
25.4
± 0.4
7.8
± <0.1
Major Subsystems
Rehoboth
Bay
1.3
± 0.2
37
± 11
29.7
± 0.8
25.7
± 0.8
7.7
± 0.1
Indian
River
1.5
± 0.2
60
± 11
28.7
± 0.6
24.9
± 1.1
7.7
± 0.1
Assawoman
Bay
1.4
± 0.2
44
± 13
29.7
± 0.5
27.4
± 1.1
8.0
± 0.1
Chincoteague
Bay
1.5
± 0.1
35
± 9
32.2
± 0.7
24.9
± 0.6
7.8
± 0.1
Target Areas
Upper
Indian
River
1.5
± 0.2
71
± 9
24.3
± 1.5
28.0
± 1.0
7.7
± 0.1
St. Martin
River
1.3
± 0.1
58
± 9
28.6
± 0.9
27.4
± 0.6
7.8
± 0.1
Trappe Creek/
Newport Bay
1.6
± 0.1
65
± 9
25.9
± 2.2
25.7
± 0.7
7.8
± 0.1
Artificial
Lagoons
1.8
± 0.4
59
± 13
29.2
± 1.3
26.4
t 1.6
7.6
± 0.3
I
-------
RthofeothBcy
Indian Rhwr
7S"16'
| 20% (Sand)
I 80% (Mud)
5 KM
Maryland State Plane Projection
N
A
7TOO'
38°4S'
38*30*
38"15'
Figure 3-1, Spatial distribution of silt-clay content in non-lagoon sites in die Delaware/
Maryland coastal bays study area. Bar height is directly proportional to the percent of silt*
day. Cross-hatched bars represent sandy sediments, clear bars represent mixed sediments, and
solid bars represent muddy sediments.
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 18
-------
6.
Chlncoteague
f
Figure 3-2. Composition of bottom sediments In the major subsystems of the Delaware/Maryland coastal bays.
-------
higher than in the other three systems, and the
percentage of muddy substrate was twice that of
any other system (Table 3-1).
3.2.3 Salinity
The coastal bays were predominantly polyhaline
(> 25 ppt salinity). Average salinity in
Chincoteague Bay was about 2 ppt greater than
in the other three coastal bays (Table 3-1). No
measured area in Chincoteague Bay had salinity
less than 25 ppt, whereas salinities less than 25
ppt accounted for at least 5% of the area in each
of the other major subsystems (Figure 3-3).
Only Indian River had measured salinities less
than 18 ppt; this salinity class encompassed
approximately 5% of the area. Some unsampled
portions of the coastal bays undoubtedly have
lower salinities but the percentage of area they
represent is small.
3.2.4 Temperature and pH
Average temperature for the coastal bays was
25.5 C and average pH was 7.8 (Table 3-1).
Neither parameter varied appreciably among the
four major subsystems.
3.3 TARGET AREAS
3.3.1 Depth
Average depths in the special target areas were
not significantly different than the average depth
of the entire study area. Average depths of the
four special target areas ranged from 1.3 m to
1.8 m (Table 3-1).
3.3.2 Silt-Clay Content
All of the special target areas were significantly
muddier than the coastal bays as a whole (Table
3-1). The upper Indian River was the muddiest;
almost half of the area had a silt-clay content of
greater than 80% (Figure 3-4). Sandy substrate
covered less than 20% of each of the four
special target areas. Less than 10% of the upper
Indian River had sandy sediments.
3.3.3 Salinity
The special target areas were predominantly
polyhaline, but average salinities in all special
target areas except the dead-end canals were
less than that of the entire study area (Table
3-1). Approximately 40% of upper Indian River
had salinities less than 25 ppt (Figure 3-5). The
closed-ended dead-end canals, which have no
freshwater input, were almost completely
polyhaline. All other systems had sources of
fresh water.
3.3.4 Temperature and pH
All special target areas had higher average
temperatures than the entire study area (Table
3-1). The maximum temperature of 37.4 C was
measured in the discharge canal of a power
generating station in upper Indian River. The
average pH levels of the special target areas
were not significantly different than the average
pH of the entire study area. The highest pH
(9.4) was measured at the uppermost sampling
site in Trappe Creek.
CONDITION OFDELA WARE AND MARYLAND BA YS
Page 20
-------
100%
I
6
0%
• >25ppt
01S-25ppt
• 5-18ppt
• 0.5-5 ppt
• < 0.5 ppt
Entire Area RehobothBay Indian River AssawomanBay Chincoteague
Figure 3-3. Percent of area in three salinity classes in the major subsystems of the Delaware/Maryland coastal bays.
-------
I
6
50
§
5
a.
Upper
Indian
River
Trappe
Creek
Dead-end
Canals
• >80% Silt-Clay
D 20-80% Silt-Clay
• <20%Silt-Clay
Figure 3-4. Composition of bottom sediments in special target areas in the Delaware/Maryland coastal bays.
-------
1
o
3
ts
»
•S
i
is
Dead-end
Canals
Figure 3-5. Percent of area in four salinity classes in special target areas in the Delaware/Maryland coastal bays.
-------
3.4 COMPARISON WITH PREVIOUS
STUDIES
Physical characteristics measured during the
1993 coastal bays study generally agree with .
those reported in previous characterizations of
the Maryland (Boynton et al. 1993) and
Delaware (Weston 1993) coastal bays.
Rehoboth Bay and Indian River are described as
shallow systems with an average depth less than
2 m; the eastern third of Rehoboth averages less
than 1 m deep. Average depths of about 1.2 m
are reported for Maryland bays, including
Chincoteague and Assawoman.
Fang et al. (1977) described the Maryland
coastal bays as a polyhaline environment;
similarly, Rehoboth Bay and lower Indian River
were classified as polyhaline in the Weston
(1993) characterization. The salinity range
measured in upper Indian River during our study
did not vary appreciably from similar data
reported in the Weston (1993) characterization.
Maps of the areal distribution of bottom
sediments, as reported by Bartberger and Biggs
(1970) in Maryland and by Chrzastowski (1986)
in Delaware are generally similar to those from
this study, but a few minor differences can be
noted. The previous characterization described
Rehoboth Bay as predominantly sand (41%),
with equal proportions of mixed and muddy
sediments. In our study, Rehoboth Bay was
sandier (53%) and less muddy (17%). Indian
River was previously described as approximately
equal proportions of muddy and sandy sediments
(Chrzastowski 1986); our study found a higher
proportion of mixed sediments and a lesser
percent of sandy sediments. These minor
differences could result from changes in
conditions over the last decade, but more likely
result from differences in the study design
(previous studies did not use a probability-based
sampling design) or from minor differences in
how mud and sand were defined between
studies.
3.5 COMPARISON TO
SURROUNDING SYSTEMS
One design feature of the coastal bays study is
that it was conducted using the same sampling
design, methodologies, and quality assurance/
quality control procedures as EPA's EMAP,
allowing comparisons between the coastal bays
and other major estuarine systems in EPA
Region HI that are sampled by EMAP, such as
Chesapeake Bay and the Delaware Bay. When
such comparisons are conducted, the coastal
bays are found to be shallower, saltier, and
muddier than either the Chesapeake Bay or
Delaware Bay. Average depths of 8.3 m in
Chesapeake Bay and 7.0 m in Delaware Bay
are approximately 5 m deeper than the coastal
bays. Both of these deeper systems include
areas which exceed 40 m in depth. In contrast,
none of the 200 sample sites in the coastal bays
exceeded 4 m in depth.
The average silt-clay content was higher in the
coastal bays than in the other two systems. The
silt-clay content for the coastal bays was 40%,
compared to 34% for Chesapeake Bay and 24%
for Delaware Bay. Mean bottom salinity in the
coastal bays (30.6 ppt) was substantially higher
than in either Chesapeake Bay (18.5 ppt) or
Delaware Bay (22.5 ppt), reflecting the meager
freshwater input to the coastal bays.
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 24
-------
4,0 W^TER QUALITY
4.1 BACKGROUND
Healthy aquatic ecosystems require clear water,
acceptable concentrations of dissolved oxygen,
limited concentrations of phytoplankton, and
appropriate concentrations of nutrients; Clear
water is a critical requirement for submerged
aquatic vegetation (SAV), which provides
habitat for many other aquatic organisms
(Dennison et al. 1993). As large concentrations
of suspended sediment or algal blooms reduce
water clarity, the amount of sunlight reaching
SAV is diminished and the plants fail to thrive;
consequently, critical habitat for crabs, fish, and
other aquatic organisms is lost (Magnien et al.
1995). Nutrient enrichment causes excessive
algal growth in the water column and on the
surfaces of plants. As bacteria metabolize
senescent excess algae, they deplete dissolved
oxygen in the water column and sediments
causing hypoxia and, in extreme cases, anoxia.
Water quality in the coastal bays of Delaware
and Maryland was evaluated using four classes
of indicators; measures of algal productivity,
dissolved oxygen (DO), water clarity, and
nutrients. Measures of algal biomass included
the concentrations of chlorophyll in the water
column and sediment, and phaeophy tin. Secchi
depth, total suspended solids (TSS), and
turbidity were measured to assess water clarity.
Nutrient measures included dissolved inorganic
nitrogen (DIN; nitrite, nitrate, and ammonium),
dissolved inorganic phosphorus (DIP), total
dissolved nitrogen (TDN), total dissolved
phosphorus (TDP), and particulate nitrogen and
phosphorus.
Estimating the percent of area showing
symptoms of eutriphication in the coastal bays
requires identifying threshold levels for selected
indicators that define eutrophication. While no
such levels have been established for the coastal
bays, the Chesapeake Bay Program has
established thresholds for five water quality
parameters to define critical habitat requirements
for supporting SAV in a polyhaline environment
(Dennison et al. 1993); these thresholds were
used for our assessment (Table 4-1). All but one
of the SAV restoration goal attributes were
measured directly. The light attenuation
coefficient was calculated from secchi depth
measurements.
4.2 MAJOR SUBSYSTEMS
4.2.1 Measures of Algal Productivity
The mean concentration of chlorophyll a in the
water column varied considerably among the
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 25
-------
Table 4-1. Chesapeake Bay submerged aquatic vegetation habitat requirements for a
polyhaline environment (Dennison et al. 1993).
Parameter
Light attenuation coefficient (kd; nr1)
Total suspended solid (mg/1)
Chlorophyll a 0/g/l)
Dissolved inorganic nitrogen (/uM)
Dissolved inorganic phosphorus 0/M)
Critical Value
1.5
15
15
10
0.67
coastal bays. The mean concentration in
Chincoteague Bay was significantly less than the
concentrations in any of the other three major
subsystems (Table 4-2). Indian River had the
largest mean concentration, almost four times
that of Chincoteague Bay. Average phaeophytin
concentrations were distributed similarly.
A significantly smaller portion of Chincoteague
Bay had chlorophyll a concentrations exceeding
the 15 ug/ml SAV restoration goal than any of
the other systems (Figure 4-1). The percentage
of area exceeding the threshold in the other
systems ranged from four to six times that in
Chincoteague Bay, and the differences were
statistically significant (Figure 4-1). Almost
25% of the area in Indian River had chlorophyll
a concentrations exceeding 30 ug/ml.
Average concentrations of chlorophyll in benthic
sediment did not vary appreciably among coastal
bays systems, except for Rehoboth Bay.
Concentrations in Rehoboth Bay were two to
four times greater than concentrations in the
other systems (Table 4-2).
4.2.2 Dissolved Oxygen
Mean concentrations of DO ranged from 5.9
ppm to 6.7 ppm and did not vary appreciably
among the four major subsystems (Table 4-2).
Only Indian River had DO concentrations less
than 5 ppm, (the state standard in both states) in
more than 10% of its area (Figure 4-2). None of
the major subsystems had measured DO
concentrations less than 2 ppm, but the extent of
low dissolved oxygen may be underestimated in
this study because measurements were limited to
daytime hours.
4.2.3 Measures of Water Clarity
Indicators of water clarity were consistently
better in Chincoteague Bay than in the other
systems. Chincoteague Bay had the highest
mean secchi depth, approximately 1 m (Table
4-2). Average secchi depth is underestimated in
our study for all of the major subsystems, except
Assawoman Bay, because it included
measurements when the secchi disk was
readable on the bottom.
CONDITION OFDELA WARE AND MARYLAND BA YS
Page 26
-------
I
s
*
20
10
Entire Ami
ReftobotftBay
Indian River
Assawoman Bay
Chlrvcotoagua
Figure 4-1. Percent of area (90% C.I.) in major subsystems of the Delaware/Maryland coastal bays which exceeded the
SAV restoration.
-------
I
[able 4-2. Area-weighted means of water quillty parameters (90V. confidence Intervals)
Parameters
Entire
Study
Area
Major Subsystems
Rehoboth
Bay
Indian
Paver
Assaworaan
Bay
Chlncoteague
Bay
Measures of Primary Production
Chlorophyll a (pg/1)
Phaeophyt'n (ugA)
Benthic Chlorophyll (ug/g)
Dissolved Oxygen (ppm)
12.17
±1.97
4.39
±0.31
8.06
±1.40
6.3
±0.2
13.31
±2.85
5.45
±0.91
22.10
±7.54
6.7
±0.4
20.68
±4.21
9.94
±1.86
9.71
±2.29
5.9
±0.3
15.78
±1.52
5.60
±0.50
6.22
±1.73
62
±0.4
5.66
±1.31
2.61
±0.37
5.45
±2.02
6.3
±0.3
Nutrients
Nitrites Nitrate (pM)
Ammonium (uM)
Total Dissolved Nitrogen (uM)
Orthophosphate (uM)
Total Dissolved Phosphorus (uM)
Total Paniculate Ntrogen (van)
Total Paniculate Phosphorus (pg/1)
Total Paniculate Carbon (ug/l)
0.79
±0.30
4.81
±1.07
28.73
±1.34
0.40
±0.06
0.93
±0.06
357
±27
47.91
±3.66
2,245
±180
0.64
±0.44
4.19
±1.21
21.19
±1.99
0.60
±0.13
1.17
±0.15
367
±70
51.75
±6.20
2,342
±463
3.38
±Z08
8.47
±2.77
27.57
±323
0.53
±0.08
0.98
±0. 11
421
±60
63.97
±8.45
2,479
±341
0.31
±0.21
6.07
±3.09
33.41
±4.38
0.27
±0.07
0.82
10.04
620
±56
77.10
±5.41
3,968
±412
0.35
±0.12
4.12
±1.74
27.43
±1.72
0.34
±0.07
0.88
±0.07
209
±30
28.72
±4.46
1,277
±203
Water Clarity
Secchi Depth
-------
I
E
5
s
90
SO T
25
20
#
10
5
D2-Sppm
• <2ppm
Entire Area
Rehoboth Bay
Mian River Assawoman Bay Chincoteague
I
Figure 4-2. Percent of area (90% C.I.) in major subsystems of the Delaware/Maryland coastal bays with dissolved oxygen
levels below the State water quality standard (5 ppm) for Maryland and Delaware.
-------
The light attenuation coefficient (Kd) was
calculated as 1.65/secchi depth (m) (Giesen et
al. 1990). More than 55% of the area in each of
the major subsystems exceeded the SAY
restoration goal Kd threshold of 1.5 rnf1 (Figure
4-3). No portion of the area in Assawoman Bay
had a Kd value below the critical threshold.
Consistent with the light attenuation results,
average concentrations for both total suspended
solids and turbidity measurements were lowest
in Chincoteague Bay (Table 4-2). Chincoteague
Bay also had the largest proportion of area with
TSS concentrations below the 15 mg/1 SAV
restoration goal (Figure 4-4). The percentage of
area below this value was significantly smaller in
Chincoteague than in either major system in
Delaware, but was not significantly different
than Assawoman Bay.
4.2.4 Nutrients
Mean concentrations of nitrate/nitrite and
ammonium were highest and total dissolved
nitrogen was second-highest in Indian River
(Table 4-2). For nitrate/nitrite, average
concentration in Indian River was 5 to 10 times
and significantly greater than in any other major
subsystem. Almost 15% of the area in the
coastal bays failed the SAV restoration goal of
10 nM for DIN (Figure 4-5). This percentage
was highest, exceeding 30%, in Indian River.
Mean DIP concentration in the two Delaware
systems was approximately twice as high, and
significantly greater, than the levels in both
Maryland systems (Table 4-2). The difference
between states was also apparent in the percent
of area exceeding the 0.67 \i M SAV restoration
goal for DIP (Figure 4-6). Thirty percent of the
area in each of the Delaware systems exceeded
that goal; in contrast, only 1% of the area in
Assawoman Bay was above the DIP SAV
restoration goal.
Mean concentrations of participate nitrogen,
carbon, and phosphorus were significantly higher
in Assawoman Bay than in the other three major
subsystems (Table 4-2). Levels were lowest in
Chincoteague Bay, where they were about three
times lower than in Assawoman Bay.
4.2.5 SAV Restoration Goals
Less than 25% of the area in the coastal bays
met all of the SAV restoration goals (Figure
4-7). This percentage was significantly higher in
Chincoteague Bay, which is the only major
subsystem with substantial SAV currently
growing (Orth et al. 1994, Orth and Moore
1988), than any of the other coastal bays
systems (Figure 4-8). The percentage was
lowest in Assawoman Bay, where none of the
sampled locations met all of the SAV restoration
goals.
Two of the SAV restoration goal parameters,
TSS and light attenuation coefficient, are
strongly influenced by physical mixing
characteristics of the system and are not easily
controlled by management action. The action of
the wind and waves combined with the average
shallow depth and poor flushing characteristics
of the coastal bays cause the bays to retain and
resuspend fine sediments, making the water
turbid. Because of this, the amount of area in
the system meeting SAV goals was reassessed
considering only the parameters that are most
controllable by management actions: chlorophyll
a, DIN, and DIP. When examined in this
fashion, almost half the area in the coastal bays
still fails to meet the goals; however, the
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 30
-------
I
I
3
6
>3
I
2s
Entire) AIM
Be ho bo Hi Bay
MdtanfflyBr
Araawomn Buy CMncototgua
I
Figure 4-3. Percent of area (90% C.I,) in major subsystems of the Delaware/Maryland coastal bays which exceeded the
SAV restoration goals for light attenuation coefficient (led = 1-5 "'').
-------
I
I
I
fe
I
fe
Entire Area
CMncetugua
Figure 4-4. Percent of area (90% C.I.) in major subsystems of the Delaware/Maryland coastal bays which exceeded the SA V
restoration goals for total suspended solids (IS rag/1).
-------
I
EnUraAm
R*haboUiB*y
bxfviRiMr
CMncolsague
I
13
Figure 4-5. Percent of area (90% C.I.) in major subsystems of the Delaware/Maryland coastal bays which exceeded the
SAV restoration goals for dissolved organic nitrogen
-------
I
§
I
I
B
I
5
3
10
Entire Area
RehobothBay Indian River Assawoman Bay Chlncoteague
*
3K
Figure 4-6. Percent of area (90% C.I.) in major subsystems of the Delaware/Maryland coastal bays which exceeded the
SAV restoration goals for dissolved inorganic phosphorus (0.67 AiM).
-------
I
I
i
Entire Area
I
fc
Figure 4-7. Percent of area (90% C.I.) in major subsystems of the Delaware/Maryland coastal bays which meets SAV
restoration goals attributes.
-------
Rahoboth Bay
Indian Rlvar
a M**t« all SAV habitat mqulremtnts
I Faflaforan
I 1 5 KM
Mirylind Stt* Plm Protection
38°45'
3T301
N
A
[7SMS1
38*1 ff
Figure 4-8. Spatial distribution of non-lagoon sites in the Delaware/Maryland coastal bays study
area which met the SAY restoration goals. Cross-hatched bars represent sites where all goals
attributes were met; clear bars represent sites where a subset of attributes were met, with height of
the bar proportional to the number of attributes failed; and solid bars represent sites where no
attributes were met.
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 36
-------
proportion-of area in Chincoteague Bay which
meets the goals for the three attributes increases
to more than 80% (Figure 4-9).
43 TARGET ARE AS
4.3.1 Measures of Algal Productivity
Mean concentrations of chlorophyll a were
significantly higher in all special target areas
than in thevstudy area as a whole (Table 4-2).
Trappe Creek/Newport Bay had the highest
concentration, four times that of the entire study
area. At least two sites in the upper portion of
Trappe Creek had concentrations of chlorophyll
a exceeding 350 |i g/1 (Figure 4-10); algal
blooms were evident at both sites. Mean
phaeophytin concentration patterns differed,
however, with average concentrations two to
four times higher in the other systems than in
Trappe Creek/Newport Bay.
More than 70% of the area in upper Indian
River, St Martin River, and the dead-end canals
had chlorophyll a concentrations exceeding 15 \i
g/1 (Figure 4-11)). Almost the entire area of
upper Indian River had levels exceeding 15 \i g/1;
more than 50% of the area exceeded 30 \i g/I.
Average measured concentrations of benthie
chlorophyll in most of the special target areas
were similar to the average concentration in the
entire study area (Table 4-2). The dead-end
canals were a large exception to the results;
average concentrations of benthie chlorophyll
were more than five times larger in the canals
than in the remaining study area.
4.3.2 Dissolved Oxygen
Except for the dead-end canals, mean
concentrations of DO in the special target areas
did not vary appreciably from the average DO
concentration in the entire study area (Table
4-2). The canals had a mean dissolved
concentration less than 4 ppm, significantly lower
than the entire study area.
Differences in DO concentrations were more
pronounced when evaluated by proportion of
area. The percentage of area with DO less than
the state standard of 5 ppm was three to seven
times greater in the special target areas than in
the entire study area (Figure 4-12). Dead-end
canals were the most hypoxic systems. More
than 55% of the area in dead-end canals had DO
less than 5 ppm; more than 30% of that area had
concentrations less than 2 ppm.
4.3.3 Measures of Water Clarity
Water clarity and TSS did not differ
significantly between any of the special target
areas and the coastal bays as a whole (Table
4-2). The pattern was similar when looking at
the proportion of area with TSS concentrations
greater than the SAV restoration goal of 15 mg/
I. The percentages for all special target areas,
except dead-end canals, were slightly higher than
for the entire study area, but the differences
were not statistically significant.
4.3.4 Nutrients
Mean concentrations of nitrate/nitrite varied
considerably among special target areas, ranging
from 0.10 to 9.15 \* M (Table 4-2). St. Martin
River had the lowest concentration; upper Indian
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 37
-------
i
Entire Area
Rehoboth Bay
Indian River
Assawoman Bay
Chincoteague
*
Figure 4-9. Percent of area (90% C J.) in major subsystems of the Delaware/Maryland coastal bays which met the SA V
restoration goals for chlorophyll and nutrients.
-------
Rehoboth Bay
Indian River
St Martin River
Trap p« Creek/
Newport Bay
Chlneotragu* Bay
1Stig/I
5KM
\7S'W
N
A
I TS'Off
38*46
38^30'
38*15'
Figure 4-10. Spatial distribution of chlorophyll a concentrations at non-lagoon sites in the
Delaware/Maryland coastal bays study area. Black-shaded bars represent concentrations which
exceeded the SAV restoration goal for chlorophyll a (15 ,ug/L)
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 39
-------
1
1
I
a
6
Entire Study Area Upper Indian River St Martin River
I
Figure 4-11. Percent of area (99% C.I.) in special target areas in the Delaware/Maryland coastal bays which exceeded the
SAV restoration goals for chlorophyll a (IS /
-------
I
.6
100
90
80
70
60
* 40
30 •
20
10
0
Entire Study Area
Upper Indian Rhrtr
St Martin River
Trappe Creek
I
Figure 4-12. Percent of area (90% C.I.) in special target areas in the Delaware/Maryland coastal bays with dissolved
oxygen levels below the state water quality standard (5 ppm) for Maryland and Delaware,
-------
River had the highest concentrations, and both
concentrations were significantly different than
the average for the entire study area. Upper
Indian River also had a significantly higher
average concentration of ammonium than the
entire study area.
Average DIN did not vary appreciably between
three of the four special target areas and the
entire study area, but upper Indian River had
significantly greater levels, more than three
times higher than the entire study area and the
other three systems (Table 4-2). The proportion
of area that failed to meet the SAV restoration
goal for DIN was more than 50% in upper
Indian River, almost three times greater than in
the remaining coastal bays (Figure 4-13).
All special target areas had mean concentrations
of total dissolved nitrogen greater than the
average for the entire study area; however, only
Trappe Creek/Newport Bay and upper Indian
River were significantly higher then the entire
study area (Table 4-2).
Mean concentrations of DIP in the upper Indian
River, St. Martin River, and the dead-end canals.
were similar to the mean for the entire study
area (Table 4-2). The mean concentration in
TJrappe Creek/Newport Bay was twice as high
as the mean for the entire study area, but the
difference was not statistically significant The
pattern was somewhat different when expressed
as areal extent. Both upper Indian River and
Trappe Creek/Newport Bay had-approximately
twice the proportion of area with DIP
concentrations greater than 0.67 |i M, compared
to the entire study area (Figure 4-14).
The mean concentration of participate nitrogen,
phosphorus, and carbon were all significantly
higher in the special target areas than in the
coastal bays as a whole (Table 4-2). No
significant differences among the special target
areas were found for any of the particulate
parameters (Table 4-2).
4.3.5 SAV Restoration Goals
None of the samples collected in the special
target areas met the SAV restoration goals.
Even when considering only the nitrogen,
phosphorus, and chlorophyll goals, less than
20% of the area in three of the systems met the
goals (Figure 4-15).
4.4 COMPARISON WITH PREVIOUS
STUDIES
Consistent with previous characterizations of the
coastal bays (Weston 1993, Boynton et al.
1993), we found moderate eutrophication in the
system with the highest nutrientAchlorophyll
concentrations occurring in the tributaries.
Consistent with Weston (1993), we observed a
significant inverse salinity:nutrient correlation,
suggesting that the tributaries are a significant
nutrient source for the coastal bays. While we
found eutrophication to be widespread in the
coastal bays, we found mat eutrophication has
not translated into a widespread hypoxia
'problem. Oxygen concentrations less than 5 ppm
were observed in only 8% of the area of the
coastal bays, though it was as high as 25% in
upper Indian River and St Martin River. This is
consistent with previous studies in which
concentrations of dissolved oxygen less than 5
ppm were rarely measured and were spatially
limited to known target areas of management
concern.
CONDITION OF DELAWARE AND MARYLAND BAYS
42
-------
I
fc
Entire Study Are* Upptr Indian Rlwr
Figure 4*13. Percent of area (90% C.I.) In special target areas in the Delaware/Maryland coastal bays which exceeded SAV
restoration goals for dissolved inorganic nitrogen (10 /M),
-------
I
I
I
1
Entire Study Area Upper Indian River St. Martin River
Trappe Creek
Dead-end
Canals
I
Figure 4-14. Percent of area (90% C.I.) in special target areas in the Delaware/Maryland coastal bays which exceeded SAV
restoration goals for dissolved inorganic phosphorus (0.67 /*M).
-------
1
I
1
I
I
10
Entire Study Ana Upper Indian Rlvw
St Martin River
Trappe Creek
Dead-end
Canals
I
Figure 4-15. Percent of area (90% C.I.) in special target areas in the Delaware/Maryland coastal bays which met SAV
restoration goals for dissolved nutrients and chlorophyll.
-------
The amount of hypoxic area in the coastal bays
may be underestimated because our
measurements were limited to daytime hours. A
part of this study, continuously recording
dissolved oxygen meters were deployed for up
to three weeks at 15 sites in the coastal bays.
Detailed analyses of those data will be a future
part of the joint assessment, but initial
observations are that diumal oxygen patterns in
the coastal bays, with the exception of Trappe
Creek are small. This is consistent with historic
diumal measurements in the coastal bays
(Boynton et al. 1993) and suggests that our
spatial estimate of hypoxia in the coastal bays is
not a severe underestimate.
The apparent conflict between widespread
eutrophication, as measured by the SAV
Restoration Goals, and the apparent limited
spatial extent of hypoxia may be explained by
the physical characteristics of the system. The
coastal bays are shallow and well mixed, which
serves to reaerate the system quickly. The
presence of hypoxia under these conditions, as
occurs in 25% of the area in St. Martin River
and upper Indian River, is indicative of
substantial eutrophication concern.
While it was not the goal of this report to assess
historical data for trend analysis, both previous
characterizations of the coastal bays (Weston
1993, Boynton et al. 1993) noted that both
chlorophyll and nutrient concentrations have
declined throughout the coastal bays during the
last two decades. Our data are consistent with
that pattern. Summer chlorophyll
concentrations in the Maryland coastal bays
have declined by more than 50% since 1975
(Figure 4-16) and similar declines have occurred
in the Delaware coastal bays (Lacoutre and
Sellner 1988). Nitrogen concentrations in our
study were approximately one-half of the values
reported by Boynton et al. (1993) and Weston
(1993) for historic studies, consistent with
Weston's suggestion that nitrogen inputs to the
system have declined during the last two
decades. While these temporal patterns are
consistent across a number of studies and
parameters, more extensive examination of these
trends needs to be conducted to ensure that the
concentration differences observed among years
do not result from inconsistencies in sampling
design or measurement methodologies.
45 COMPARISON TO
SURROUNDING SYSTEMS
Nutrient concentrations are not measured
typically as part of the EMAP sampling and
comparisons of these parameters to other
Delaware and Chesapeake data sets is beyond
the scope of mis data summary report. Recent
assessment reports by the Chesapeake Bay
Program (Magnien et al. 1995) have identified
that about 75% of the area in Chesapeake Bay
meets the SAV restoration goals, which is triple
the proportion of area in the coastal bays. In
Chesapeake Bay, 90% of the area meets four of
the five SAV goal attributes, whereas only 32%
of the area in the coastal bays meets the same
goals. The Chesapeake Bay estimate is not
based on probability-based sampling and may
include multiple months of data for each site.
Thus, the estimate may not be directly
comparable to that from this study, but the
magnitude of the difference between estimates
for the systems appears to transcend minor
methodological differences between studies.
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 46
-------
1
I
I
-4
50
46
40
35
30
25
20
15
10
5
0
-St Martin River
- Newport Bay
-Assawoman Bay
- Chincoteague Bay
1975
1980
1985
1990
1995
Figure 4-16, Summer average chlorophyll a concentrations for major subsystems of the Delaware/Maryland coastal bays.
Sources: Fang et al. (1977), Maryland Department of the Environment (1983), National Park Service (1991), and the
present study.
-------
5.0 SEDIMENT CONTAMINANTS
5.1 INTRODUCTION
The scientific and popular presses have identified
the presence of contaminants in estuaries as a
problem contributing to degraded ecological
resources and concerns about the safety of
consuming fish and shellfish (Broutman and
Leonard 1988, NOAA 1990, OTA 1987,
O'Connor 1990). Reducing contaminant inuts
and concentrations, therefore, is often a major
focus of regulatory programs for estuaries.
Contaminants include inorganic (metals) and
organic chemicals originating from many sources
such as atmospheric deposition, freshwater
inputs, land runoff, and point sources. These
sources are poorly characterized except in the
most well-studied estuaries. Most contaminants
that are potentially toxic to biological resources
tend to bind to particles and ultimately are
deposited in the bottom of estuaries (Santschi et
a!. 1980, Santschi 1984). This binding removes
contaminants from the water column.
Consequently, contaminants accumulate in
estuarine sediments (Santschi et al. 1984).
Because of the complex nature of sediment
geochemistry, and possible additive, synergistic,
and antagonistic interactions among multiple
pollutants, the ecological impact of elevated
contaminant levels in bottom sediments is not
well understood. Several strategies for
estimating biological effects from contaminated
sediments include the EPA Sediment Quality
Criteria approach (U.S. EPA 1993a-d), the Long
and Morgan approach (Long and Morgan 1990,'
Long et al. 1995), and the SEM/AVS
(simultaneously extracted metals/acid volatile •'
sulfides) approach (DiToro et al. 1989,1990 and
1992). Because these various techniques result
in different estimates, definitive estimates of
those areas of the coastal bays with contaminant
concentration high enough to cause ecological
impacts cannot be provided with confidence .
(Strobel et al. 1995). For this reason, the
analyses presented in this Section are provided
for screening purposes only.
The guideline values developed by Long and
Morgan (1990) and recently updated by Long et
al. (1995) were used to screen contaminant
levels in coastal bay sediments with respect to
potential biological effects. These values were
selected because they include values for most of
the chemicals we measured, thus allowing us to
provide the most complete evaluation of the data.
Two values were identified for each
contaminant: an effects range-low (ER-L) value
corresponding to contaminant concentrations
below which adverse effects to benthic
organisms "rarely" occur, and an effects range-
CONDIJJON OF DELAWARE AND MARYLAND BAYS
Page 48
-------
Table 5-1. ER-L and ER-M guideline values for trace metals and organic compounds in
sediments. Sources: Long and Morgan (1990), Long et al. (1995).
Chemical
Analyte
Trace Elements (ppm)
Antimony
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Silver
Zinc
PolychJortaated Biphenyb (ppb)
Total PCBs
DDT and Metabolites (ppb)
DDT
ODD
DDE
Total DDT
PPDDE
Other Pesticides (ppb)
Chlordane
Dieldrin
Endrin
Polynuclear Aromatic Hydrocarbons (ppb)
Acenaphthene
Acenaphthylene
PAH (high mol. wt)
PAHdowmol.wt.)
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Chrysene
Dibenz(a,h)anthracene
Fhioranthene
Fluorene
2-methylnaphthalene
Naphthalene
Phenanthrene ,
Pyrene
TotalPAH
ER-L
Concentration
2
8.2
1.2
81
34
46.7
0.15
20.9
1
150
22.7
1
2
2
1.58
22
0.5
0.02
0.02
16
44
1700
552
85.3
261
430
384
63.4
600
19
70
160
240
665
4022
ER-M
Concentration
25 •
70
9.6
370
270
218
0.71
51.6
3.7
410
180
7
20
15
46.1
27
6
8
45
500
640
9600
3160
1100
1600
1600
2800
260
5100
540
670
2100
1500
2600
44792
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 49
-------
Rehoboth Bay
Indian River
Aasawoman Bay
SL Martin River •
• 0 Contaminants
I 10 Contaminant*
* Inekidea one contaminant
greater than ER-M
I 1 5 KM
ttanrfuid Slat* Plan* Projection
38°46
Trappe Creek/
Newport Bay
38'SO1
N
A
|7S°1g
I TS-OO'
Figure 5-1. Spatial distribution of sites (including dead-end canals) for which sediment
contaminants were analyzed. Bar height is directly proportional to number of-sediment
contaminants which exceeded ER-L threshold concentrations. Asterisk indicates sites where a
contaminant exceeded ER-M concentration.
CONDITION OFDELA WARE AND MARYLAND BA YS
Page 50
-------
I
I
.&
I
I
B
I Dead-end Canals
I Coastal Bays
DDT
Arewilc
Chlordane
Dieldrin
Nickel
I
Figure 5*2. Percent of area with concentrations exceeding ER-L values for the five most prevalent contaminants in the
Delaware/Maryland coastal bays.
-------
Table 5-2. Area-weighted mean concentrations (± 90% C.I.) of sediment contaminants in the
Coastal Bays and Dead-End Canals
Metals (ppm)
Silver
Arsenic
Cadmium
Chromium
Copper
Lead
Nickel
Zinc
Pesticides (ppb)
Chlordane
Total DDT
Lindane
Mirex
Endrin
Dieldrin
Total PAHs (ppb)
Total PCBs (ppb)
Coastal Bays
0.05 ± 0.02
7.03 ± 1.91
0.14 ± 0.05
41.98 ± 10.58
9.52 ± 2.81
24.14 ± 5.83
13.93 ± 4.65
64.53 ± 16.35
0.41 ± 0.39
2.15 ± 0.87
0.20 ±0.15
0.12 ± 0.17
0.04 ± 0.02
0.13 ± 0.07
232.33 ± 92.43
2.89 ±1.04
Dead-end Canals
0.1 ± < 0.1
10.6 ± 2
0.2 ± <0.1
.56.1 ± 21.7
40.6 ± 10.3
34.4 ± 6.6
21.1 ± 9.2
107.9 ± 28.9
1.8± 0.7
3.1 ± 2.9
0.9± 0.2
0
0.5± 0.1
1.7± 1.8
2060.9 ± 1099.7
19.8 ± 5.5
median (ER-M) concentration above which
adverse effects "frequently" occur (Long et al.
1995). Adverse effects could be expected to
"occasionally" occur when the measured
concentration falls between the ER-L and ER-M
(Long et al. 1995). According to Long and
Morgan (1990), sites with the greatest number of
ER-L and ER-M exceedences have the highest
potential for cause adverse biological effects. In
those situations where there is a high potential
for adverse effects based upon exceedences of
ER-Ls and ER-Ms, EPA and others have
suggested follow-up testing such as solid phase
toxicity testing to directly measure biological
effects (Adams et al. 1992, Chapman et al. 1992,
EPA 1992). Future activities may include these
additional analyses.
Only a subset of the sediment samples collected
were processed for contaminants because of
cost constraints. Consequently, comparisons
were limited to dead-end canals (10 sites) and
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 52
-------
the coastal bays as a whole (24 sites).
at single, separate sites (Figure 5-1).
5.2 CONDITION OF THE COASTAL
BAYS
At least 1 contaminant exceeded its ER-L
concentration at 70% of the 24 sites in the
coastal bays (excluding sites in the dead-end
canals) where contaminant samples were
processed. This corresponded to 68% (± 23%)
of the total area of the system. Only four sites
(representing 4% of the area in the system) had
at least one contaminant that exceeded its ER-M
concentration.
Many sites had more than one contaminant that
exceeded its ER-L concentration. A dead-end
canal on the east side of Assawoman Bay
contained the most contaminants that exceeded
their ER-L concentrations (20). The number of
contaminants that exceeded ER-L in the coastal
bays increased from south to north. Indian River
had the most sites with multiple contaminants
exceeding ER-L and had one site with a
contaminant exceeding ER-M (Figure 5-1). The
majority of sites in Rehoboth Bay with multiple
contaminants were located in dead-end canals.
Five of the seven sites in Rehoboth Bay were
canal sites containing more then five
contaminants exceeding ER-L concentrations.
The most ubiquitous contaminants (measured as
the estimated area in which the contaminant
exceeded its ER-L concentration), were DDT,
arsenic, and nickel, with each found to exceed
ER-L in more than a quarter of the bottom of the
area of the system (Figure 5-2). DDT and its
principal metabolites were 4 of the top 10
contaminants. The only ER-M concentration
exceedances were for chlordane, dieldrin, DDE,
and benzo(a)anthracene, which were exceeded
In this study, Long et al. (1995) and Long and
Morgan (1990) ER-L and ER-M thresholds were
used as a means of estimating the areal extent of
contaminants in the coastal bays; however, other
authors have suggested alternative approaches
for identifying thresholds of biological concern
(DiToro et al. 1990,1991, 1992; EPA 1993).
Long et al. values were selected because they
included thresholds for most of the chemicals
that we measured, allowing us to provide an
integrated contaminant response, whereas other
approaches for identifying thresholds have been
developed for a relatively small number of
chemicals. These alternative thresholds, when
applied to the coastal bays data set, lead to a
smaller estimate of areal extent (Greene 1995),
suggesting that the ER-L thresholds are more
protective of the environment. Future CBJA
activities may include analyses to relate the
biological responses reported in this chapter with
the sediment contaminant data reported here.
5.3 CONDITION OF DEAD-END
CANALS
Concentrations of contaminants generally were
higher in the sediments of dead-end canals than
in the rest of the coastal bays. Fifteen of the 45
contaminants measured had significantly higher
mean concentrations in the canals. No
contaminants had significantly higher
concentrations in the rest of the coastal bays
than in the canals (Table 5-2). The difference in
concentration between canals and the coastal
bays was greatest for the polynuclear aromatic
hydrocarbons (e.g., chrysene and pyrene); the
concentrations of many of these contaminants
were 10 times higher in the dead-end canals than
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 53
-------
in the rest of the coastal bays (Appendix C).
The difference between the dead-end canals and
the rest of the coastal bays was also apparent in
the spatial extent of contamination. Of the five
most ubiquitous contaminants in the coastal bays,
none exceeded ER-L concentrations for more
than 42% of the total area of the coastal bays;
however, these contaminants each exceeded their
ER-L concentrations in more than 70% of the
area of the dead-end canals (Figure 5-2).
Seventy-five percent of the area of dead-end
canals had more than six contaminants that
exceeded their ER-L concentrations (Figure 5-3).
In contrast, only 10% of the area in the rest of
coastal bays had more than five contaminants
above ER-L, and 30% had no contaminants that
exceeded ER-L concentrations.
5.4 COMPARISON TO PREVIOUS
STUDIES
The Delaware/Maryland coastal bays study
represents to the best of our knowledge the first
substantive assessment of sediment contaminants
in the coastal bays. Although only a subset of the
sediment samples collected for contaminant
analysis were processed, the data presented in
this report represent a ten-fold increase in
available data over the last 15 years. No data
were reported in the Delaware Inland Bays
Estuary Program's characterization report
(Weston 1993) because the data found were
insufficient for a status determination. The
Maryland report (Boynton et al. 1993) contained
three years of data for a single site at
Chincoteague Inlet, VA. Three-year average
concentrations were found to be elevated relative
to detection levels but only dieldrin was measured
at concentrations of biological concern (NOAA
1991).
5.5 COMPARISON TO
SURROUNDING SYSTEMS
Sixty-eight percent of the area in the coastal
bays had at least one sediment contaminant
exceeding the Long et al. (1995) ER-L
concentration, which is a threshold of biological
concern. This was significantly greater than the
spatial extent which was observed for the same
threshold of concern in either Chesapeake Bay
(46%) or Delaware Bay (34%).
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 54
-------
I
I
s
SB
I
5
Dead-end Canals
Coastal Bays
I
IS
Figure 5-3, Area! distribution of number of sediment contaminants which exceeded ER-L values.
-------
6.0 BENTHIC MACROINVERTEBRATES
6.1 BACKGROUND
Benthic assemblages have many attributes that
make them reliable and sensitive indicators of
ecological condition (Bilyard 1987). Benthic
macroinvertebrates live in sediments, where
exposure to contaminants and low concentrations
of dissolved oxygen generally is most severe.
Their relative immobility prevents benthic
organisms from avoiding exposure to pollutants
and other environmental disturbances (Gray
1982). Benthic assemblages are composed of a
diverse array of species that display a wide
range of physiological tolerances and respond to
multiple kinds of stress (Pearson and Rosenberg
1978, Rhoads et al. 1978, Boesch and Rosenberg
1981). The life spans of benthic
macroinvertebrates are long enough (a few
months to several years) to enable researchers
to measure population- and community-level
responses to environmental stress (Wass 1967).
This combination of attributes enables benthic
assemblages to integrate environmental
conditions prevalent during the weeks and
months before a sampling event
Four measures of biological response were used
to evaluate the condition of benthic assemblages
in the coastal bays of Delaware and Maryland:
abundance, biomass, diversity, and the EMAP
benthic index. Abundance and biomass are
measures of total biological activity at a location.
The diversity of benthic organisms supported by
the habitat at a location often is considered a
measure of the relative "health" of the
environment. Diversity was evaluated using the
number of species (i.e., species richness) at a
location and the Shannon-Wiener diversity index,
which incorporates both species richness and
evenness components (Shannon and Weaver
1949). The EMAP benthic index integrates
measures of species richness, species
composition, andbiomass/abundance ratio into a
single value that distinguishes between sites of
good or poor ecological condition (Schimmel et
al. 1994). A value of 0 or less denotes a
degraded site at which the structure of the
benthic community is poor, and the number of
species, abundance of selected indicator species,
and mean biomass are small.
6.2 MAJOR SUBSYSTEMS
6.2.1 Abundance and Biomass
Indian River had significantly more benthic
invertebrates than any of the other three major
subsystems (Table 6-1). Much of this difference
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 56
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was due to a greater number of amphipods.
Amphipods accounted for about 50% of total
abundance in the coastal bays as a whole;
however, in Indian River, amphipods accounted
for more than 75% of total abundance (Figure
6-1). Biomass followed a different pattern than
abundance among the major subsystems.
Biomass was greatest in Chincoteague Bay and
smallest in Indian River (Table 6-1). The very
small ratio of biomass to abundance observed in
Indian River often is associated with degraded
habitat (Wilson and Jeffrey 1994).
6.2.2 Species Richness and Diversity
The average number of species was significantly
higher and about 50% greater in Chincoteague
Bay than in any of the other three major
subsystems (Table 6-1). Species diversity as
measured by the Shannon-Wiener diversity index
was significantly greater in Chincoteague than in
Rehoboth and Indian River, but the difference
between Chincoteague and Assawoman was not
statistically significant The presence of several
rare species that did not contribute significantly
to the Shannon-Wiener index for Chincoteague
Bay was responsible for the smaller difference in
diversity than in number of species between
Chincoteague Bay and the other major
subsystems.
6.2.3 EMAP Benthic Index
Based on mean EMAP benthic index values,
benthic communities in Indian River were
degraded and in significantly worse condition
than in any of the other major subsystems.
Benthic communities in Chincoteague Bay were
nondegraded and in significantly better condition
than in any other system (Table 6-1). The
average index in Rehoboth Bay indicated
significant degradation of benthic communities;
Assawoman Bay was nondegraded.
The estimated proportion of degraded area in the
major subsystems ranged from 77% in Indian
River to 11% in Chincoteague Bay (Figure 6-2).
Indian River had a significantly higher proportion
of degraded area than any of the other systems.
Chincoteague Bay had a significantly smaller
proportion of degraded area than Rehoboth Bay
(Figures 6-2 and 6-3). The difference in
proportion of degraded area between
Chincoteague and Assawoman was not
statistically significant. Although the average
index value indicated that Rehoboth Bay was
degraded, the difference in proportion of
nondegraded area between Rehoboth and
Assawoman was not statistically significant.
6.3 TARGET AREAS
6.3.1 Abundance and Biomass
Abundance and biomass were an order of
magnitude less in dead-end canals than in the
rest of the coastal bays (Table 6-1). The
composition of benthic communities in the dead-
end canals differed substantially from the
composition in the rest of the coastal bays.
Amphipods constituted almost 50% of the
benthos throughout the coastal bays; however,
approximately 85% of the benthos collected in
dead-end canals were polychaetes (Figure 6-4),
of which 90% were Streblespio benedicti
(Appendix C), a pollution-tolerant species
(Ranasinghe et al. 1994). Bivalves, which are
generally less pollution tolerant, constituted 12%
of the benthos in the rest of the coastal bays as
a whole, but less than 5% of that in each of the
special target areas. Differences in species
composition between the dead-end canals and
CONDITION OF DELA WARE AND MARYLAND BA YS
Page 57
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I
fiblc 6>I. Area-weighted mrim of bentbic nucrofaverttbritc parameter! (90% confidence interval!)
Parameters
Abundance prt1)
aiomass (g/nf)
Number of Species
Ptemple)
Shannon-Wiener
Index
EMAP Index
Entire
Study
Area
18,724
±2,551
10.57
±3.03
24.25
±1.19
2.73
±0.10
0.48
±0.25
Major SubiyilcDt
Rehoboth
Bay
17,556
±5,030
10.72
±9.87
18.73
±1.77
2.41
±0.19
•0.20
±0.49
Indian
River
34,889
±8,741
5.05
±1.38
17.30
±2.51
1.79
±0.36
-2.30
±0,88
Assawoman
Bay
13,846
±5,488
5.19
±1.39
20.53
±3.30
2.85
±ft31
0.35
±0.45
Chlncoteague
Bay
15,478
±2,892
13.97
±5.53
27.58
±1.98
3.02
±0.15 .
1.41
40.25
Target Areai
Upper
Indian
River
58,498
* 16,520
6.66
±1.72
18.56
i 1.70
1.96
±0.17
4.80
±1.68
St
Martin
River
30,200
±11,032
6.07
±3.41
19.20
±2.90
Z10
±0.37
-1.68
41.35
Trappe
CreeW
Newport
Bay
16,85i
±4,721
9.08
±3.23
22.76
±259
2.54
±0.22
0.24
±0.47 .
Artificial
Lagoons
1,917
±1,354
0.43
±0.33.
3.6
±2.6
0.59
±0.49
-0.57
±0.25
-------
f
I
6.
"so
'.5.
Entire Study, Behoboth Indian River Assawoman Chlncotsague
*»" . . -. . Bay . Bay
I
Figure 6-1. Composition of benthSc assemblages in the major subsystems of the Delaware/Maryland coastal bays.
-------
j
I
I
Entire Area
Bflhobotii Bay
Indian Rtvar
AssawomsnBay
Chincoteagua Bay
I
Figure 6-2. Percent of degraded area In the major subsystems of the Delaware/Maryland coastal bays, based on the EMAP
henthic index.
-------
• Bars exca«fing mi» height
Indicate degraded sites
I 1 5 KM
Mwylintf Stab Pbna Prelection
38*4?
38*30'
N
A
TBtW
Figure 6-3. Benthic index values at non-lagoon sites in the Delaware/Maryland coastal bays study
area. Bar height is inversely proportional to the index value; black-shaded bars indicate a
degraded condition.
CONDITION OF DELA WARE AND MARYLAND BA YS
Page 61
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the rest of the coastal bays are reflected in the
significantly lower biomass in the dead-end
canals. Approximately 81% of the area in dead-
end canals had a mean biomass less than 0.5 g/
m2 compared to 4% in the rest of the coastal
bays (Figure 6-5).
6.3.2 SPECIES RICHNESS
The upper Indian River, St. Martin River, and the
dead-end canals all had significantly fewer
species per sample than the rest of the coastal
bays CTable 6-1). The difference was
particularly notable in dead-end canals, where
the number of species was nearly seven times
less than in the entire study area and
approximately five or six times less than in any of
the other special target areas. Whereas, 70% of
the area in the coastal bays had at least 20
species per 440 cm2 grab, 78% of the area in the
canals produced less than 5 species per sample
(Figure 6-6).
Similar patterns were observed with the
Shannon-Wiener diversity index; the values for
the upper Indian River, St. Martin River, and the
dead-end canals all were significantly lower than
for the entire study area. The index value for the
dead-end canals was five times lower than for
the entire study area and three to four times
lower than for the other special target areas.
Diversity in Trappe Creek/Newport Bay did not
differ significantly from diversity in the rest of
the coastal bays but was low in the Trappe
Creek portion of this stratum.
of the coastal bays (Table 6-1, Figure 6-3). The
index value for Trappe Creek/ Newport Bay was
not significantly different than the value for the
rest of the coastal bays, but the Trappe Creek
portion of the stratum, where pollution sources
were most prevalent historically, was degraded.
The extent of degradation was greatest in the
dead-end canals and upper Indian River. More
than 80% of the area of these two systems had
degraded benthic communities as measured by
the EMAP benthic index (Figures 6-7 and 6-3);
this proportion was significantly greater than in
the rest of the coastal bays.
6.4 COMPARISON WITH PREVIOUS
STUDIES
Recent characterizations of the coastal bays
(Boynton et al. 1993, Weston 1993) made little
use of benthic macroinvertebrates in their
assessment. The principal limitations they cited
were that most benthic data for these systems
were collected more than 20 years ago and were
spatially limited. Moreover, the sampling efforts
were conducted primarily to characterize species
composition and habitat distribution, and did not
focus on using benthos as indicators of ecological
condition. Thus, this report represents the first
ecological assessment of benthic invertebrate
condition in the Maryland/Delaware coastal
bays.
Comparisons to these historical studies is difficult
because of differences in sampling gear and
because original data are no longer available.
The most comprehensive characterization of the
system was conducted by Maurer (1977), but he
used a 1 mm sieve which is not easily
comparable to our 0.5 mm sieve. DP&L (1976)
CONDITION OFDELA WARE AND MARYLAND BA YS
Page 62
-------
I
I
s
I
§
ss
Entil* Study Am
UpfMc IfKfim Rhw
I
Figure 6-4. Composition of benthic assemblages in special target areas in the Delaware/Maryland coastal bays.
-------
b
^
I
50
I
Dead-End Canals
Coastal Bays
• >10g
D5-10g
D1-5g
• 0.5-1 g
• < 0.5 g
I
Figure 6-5. Percent of area for biomass (g/m2) of benthic macroinvertebrates.
-------
I
I
§
B
Dead-End Canals
Coastal Bays
• > 20 Species
EJ10-20 Species
• 5-10 Species
• < 5 Species
I
Si
Figure 6-6. Percent of area for species richness of bentbic macroin vertebrates.
-------
I
p
I
5
1
ss
Entire Study Area
Upper Indian River
St Martin River
Trappe Creek
Dead-End Canals
Figure 6-7. Percent of degraded area in special target areas in the Delaware/Maryland coastal bays, according to the
EMAP benthic index.
-------
conducted the most comprehensive historic study
in Indian River, one that used the same sieve size
as the coastal bays study. Mean invertebrate
density in their study was almost an order of
magnitude less than in our study for both the
upper Indian River and the entire Indian River.
Average species density did not vary appreciably
between the two studies. The 1993 benthic
community in Indian River was dominated by
amphipods, which accounted for 75% of the total
abundance. In the polyhaline stratum of the
DP&L study, percent abundance was equally
divided among polychaetes, amphipods, and
bivalve molluscs. Together, these differences
suggest that the quality of the benthic community
has changed in the last two decades, but more
substantial analyses based on original, rather than
summarized, historic data are required to better
characterize these changes.
6.5 COMPARISON TO
SURROUNDING SYSTEMS
Benthic invertebrate communities may be in
poorer condition in the coastal bays than in
either Chesapeake or Delaware Bays.
Twenty-eight percent of the area in the coastal
bays had degraded benthic communities as
measured by EMAP's benthic index. Using the
same sampling methods and benthic index, 26%
of the area in Chesapeake Bay and 16% of the
area in Delaware Bay had degraded benthos.
CONDITION OF DELAWARE AND MARYLAND BAYS Page 67
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7.0 CONCLUSIONS
The probability-based sampling design used in
the Delaware/Maryland coastal bays joint
assessment allows for two types of estimates
that were not previously available for these
systems. First, it allows estimation of areal
extent of selected indicators exceeding threshold
levels of concern to managers. Second, it allows
unbiased comparisons among various subsystems
of the coastal bays, since the same sampling
design, sampling methodologies and quality
assurance/quality control procedures were
employed throughout the study area. The results
of the study support the following conclusions:
I. Major portions of the coastal bays have
degraded environmental quality.
Major portions of the coastal bays were found to
have degraded environmental conditions.
Twenty-eight percent of the area in the coastal
bays had degraded benthic communities, as
measured by EMAP's benthic index. More than
75% of the area in the coastal bays failed the
Chesapeake Bay Program's Submersed Aquatic
Vegetation (SAV) restoration goals, which are a
combination of measures that integrate nutrient,
chlorophyll, and water clarity parameters. Most
areas failed numerous SAV goal attributes.
About 40% of the area failed the nutrient and
chlorophyll components of the SAV Restoration
Goals. Sixty-eight percent of the area in the
coastal bays had at least one sediment
contaminant with concentrations exceeding
published guidelines for protection of benthic
organisms (Long and Morgan 1990, Long et al.
1995). Further study is needed to assess
whether the biological effects we observed are
the direct result of contamination.
2. Eutrophication threatens recolonization
of SAV in the coastal bays, but is not severe
enough to cause widespread hypoxia.
Eutrophication, as measured by the SAV
restoration goals, is widespread in the coastal
bays. With the exception of some limited areas
of management concern, eutrophication has not
yet resulted in a severe hypoxia problem that
threatens biota. Oxygen concentrations less than
5 ppm were measured in only 8% of the study
area, though it was as high as 25% of the study
area in Indian River and St. Martin River.
Oxygen concentrations less than 2 ppm were
measured only in dead-end canals. This is
consistent with previous studies, in which
concentrations of dissolved oxygen less than 5
ppm were measured rarely and were spatially
limited to known areas of management concern.
While we measured only 8% of the area as
hypoxic, this amount may be larger during
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 68
-------
nighttime hours and is a significant amount of
area, given the shallow, well-mixed nature of the
system.
3. The sediment contaminants detected in
this study are primarily persistent
chlorinated hydrocarbons and are probably a
remnant of historic inputs.
The sediment contaminants detected in this study
are primarily persistent pesticides, such as DDT,
chlordane, and dieldrin, that are no longer
commercially available orare strongly regulated,
and whose input into the system has undoubtedly
declined. The prevalence of these chemicals in
the sediments probably result, to a large extent,
from the unique physical characteristics of the
coastal bays: (1) land use in the coastal bays is
largely agricultural, and a source of non-point
pollution; (2) the system has a large perimeter to
area ratio, enhancing the potential impact of
non-point source inputs; and (3) the low flushing
rate of the system enhances the likelihood that
chemicals entering the system will be retained in
the system for long periods of time.
4. Chincoteague Bay is in the best condition
of the major subsystems within the coastal
bays Indian River is in the worst condition.
Of the four major subsystems that comprise the
coastal bays, Chincoteague Bay was in the best
condition. Only 11% of the area in
Chincoteague Bay had degraded benthos.
Almost 45% of the area in Chincoteague Bay
met the Chesapeake Bay Program's SAV
restoration goals, a figure which increased to
almost 85% when only the nutrient and
chlorophyll components of the goals were
considered. In comparison, 77% of the area in
Indian River had degraded benthos and less than
10% of its area met the SAV restoration goals.
5. The tributaries to the coastal bays are in
poorer condition than the mainstems of the
major subsystems.
Previous studies have suggested that the major
tributaries to the system: upper Indian River, St.
Martin River, and Trappe Creek are in poorer
condition than the mainstem water bodies. Our
study confirms that finding. The percentage of
area containing degraded benthos was generally
two to three times greater in the tributaries
compared to the other coastal bays. The percent
of area with DO less than the state standard of 5
ppm was three to seven times greater in the
tributaries. More than 70% of the area in upper
Indian River and St Martin River and in the
dead-end canals had chlorophyll a concentrations
exceeding the SAV goal of 15 u.g/1. None of the
samples collected in the tributaries met the SAV
restoration goals.
Among these systems, Trappe Creek contained
the sites in the worst condition. Two sites in the
upper portion of Trappe Creek had
concentrations of chlorophyll a exceeding 350
(j.g/1; algal blooms were evident at each site. In
addition, dissolved oxygen levels exceeding 14
ppm were measured at both sites. It appears,
however, that degraded conditions in the Trappe
Creek system are spatially limited to Trappe
Creek and have not spread to Newport Bay.
Undoubtedly, this results from the low
freshwater flow from this tributary compared to
the other tributaries.
6. Dead-end canals are the most severely
degraded areas in the coastal bays.
CONDITION OF DELAWARE AND MARYLAND BAYS
Page 69
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Ninety-one percent of the area in dead-end
canals had sediment contaminant concentrations
exceeding published guideline values. Fifty-six
percent of their area had dissolved oxygen
concentrations less than state standards of 5
ppm. Canals were the only locations from all the
coastal bays sites where concentrations less than
2 ppm were measured. These stresses appear
to have biological consequences: more than 85%
of the area in the dead-end canals had degraded
benthic communities. Dead-end canals averaged
fewer than 4 benthic species per sample
compared to 26 species per sample in the
remaining portions of the coastal bays.
7. Based on percent areal extent, the
coastal bays are in as poor or worse
condition than either Chesapeake Bay or
Delaware Bay with respect to sediment
contaminant levels, water quality, and
benthic macroinvertebrate community
condition.
The consistency of the sampling design and
methodologies between our study and EMAP
allows unbiased comparison of conditions in the
coastal bays with that in other major estuarine
systems in EPA Region III that are sampled by
EMAP. Based on comparison to EMAP data
collected between 1990 and 1993, the coastal
bays were found to have a similar or higher
frequency of degraded benthic communities than
surrounding systems. Twenty-eight percent of
the area in the coastal bays had degraded
benthic communities as measured by EMAP's
benthic index, which was significantly greater
than the 16% EMAP estimated for Delaware
Bay using the same methods and same index,
and was statistically indistinguishable from the
26% estimated for Chesapeake Bay. The
coastal bays also had a prevalence of chemical
contamination in the sediments that was higher
than in either Chesapeake Bay or Delaware
Bay. Sixty-eight percent of the area in the
coastal bays exceeded published guideline values
for at least one contaminant, compared to 46%
for Chesapeake Bay and 34% for Delaware Bay
(Long and Morgan 1990, Long et al. 1995).
While the percent of area having poor benthic
and sediment conditions is higher in the coastal
bays, the absolute amount of area having these
conditions is greater in the Delaware and
Chesapeake Bays, because of their larger size.
Nutrients were not measured by EMAP and
statistically unbiased estimates of average
concentrations are unavailable for. either
Chesapeake or Delaware Bays. The
Chesapeake Bay Program, though, recently
estimated that about 75% of the area in
Chesapeake Bay meets SAY Restoration Goals.
This is more than three times the percent of area
meeting SAY Restoration Goals in the coastal
bays. Even when the turbidity and TSS
components of the SAY Restoration Goals,
which are naturally high in shallow systems, are
ignored, almost half of the area in the coastal
bays, or twice that in Chesapeake Bay, still fails
the SAY Restoration Goal estimates for nutrients
and chlorophyll.
8. The fish assemblages in Maryland's
coastal bays have remained relatively
unchanged during the past twenty years,
while those of similar systems in Delaware
have changed substantially.
Fish assemblages of the Maryland coastal bays,
as sampled by shallow-water seines, are
dominated by Atlantic silversides, bay anchovy,
Atlantic menhaden, and spot. This assemblage is
similar to that of the Delaware coastal bays 35
CONDITION OFDELAWAREANDMARYLAND BAYS
.Page 70
-------
years ago. The fish fauna in Delaware's coastal
bays has shifted toward species of the Family
Cyprinodontidae (e.g., killifish and sheepshead
minnow) which are more tolerant to low oxygen
stress, and salinity and temperature extremes.
CONDITION OF DELAWARE AND MARYLAND BAYS Page 71
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Cochran, W. G. 1977. Sampling Techniques. 3rd ed. New York: John Wiley and Sons.
D'EIia, C.F., PA. Steudler, and N. Corwing. 1977, Determination of total nitrogen in aqueous samples
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Delmarva Power and Light Company. 1976. Ecological studies in the vicinity of the Indian River power
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CONDITION OF DELAWARE AND MARYLAND BAYS page 78
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APPENDIX A
1993 Delaware Fish Seine Study and Comparison
to Delaware and Maryland Historical Studies
Contributing Authors:
Kent S. Price and Maryellen Timmons
University of Delaware, College of Marine Studies
Cecelia C. Linder, James F. Casey,
Steve Doctor, and Alan Wesche
Maryland Department of Natural Resources
Janis C. Chaillou
Versar, Inc.
A-1
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DELAWARE COASTAL BAYS
SHORE ZONE FISH COMMUNITY TRENDS
Kent S. Price1, Maryellen Timmons1, and Janis C. Chaillou2
January 1996
INTRODUCTION
The general purpose of this study was to examine historical and current shore-zone fish community data to
determine whether perceived changes in the fish community could be related to spatial or temporal trends in water
quality in Delaware and Maryland's coastal inland bays. Generally, studies in fresh water have shown that
moderate eutrophication increases fish biomass, but may shift the composition of the fish community from
desirable colder water fish to rough fish such as carp (Lee, et al., 1991). The mechanism underlying the shift in
community structure is poorly understood, but Lee, et al. (1991) suggests that it is related to such factors as
reduced grazing ability of predatory fish brought about by increased turbidity from increased amounts of
phytoplankton. Almost no studies of this type have been conducted for estuarine fish. Price, et al. (1985)
suggested that the depression of striped bass stocks in the Chesapeake Bay may be related to eutrophication
through (1) loss of habitat for adult fish through reductions in dissolved oxygen in deeper waters and (2) loss of
habitat for juvenile fish through eutrophication mediated reductions in submerged aquatic vegetation. Price (U.S.
EPA, 1983} also proposed that nutrient and toxic enrichment of low-salinity spawning and nursery areas may be
related to declines in anadromous (fresh water) spawning estuarine species such as striped bass, white perch,
yellow perch, herring, and others.
1 University of Delaware, College of Marine Studies, Lewes, DE
2 Versar, Inc., Columbia, MD
A-2
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THE SETTING IN DELAWARE
Delaware's inland bays (Fig. 1) consist of three
interconnected water bodies—Rehoboth, Indian
River, and Little Assawoman bays. The inland
bays have a drainage area of about 300 square
miles, a water surface area of 32 square miles, a
marsh area of 9 square miles, a mean-low-water
volume of 4 billion cubic feet, and a freshwater
discharge of 300 cubic feet per second. Almost
30 square miles of the inland bays are classified as
shellfish waters, of which 19 square miles
presently are approved for shellfishing. There are
about 126 people per square mile of the inland
bays watershed, and the land is about 10 percent
urban, 44 percent forested, and 46 percent
agriculture. The inland bays are tidally flushed,
with estimates typically converging on 90-100
days for Indian River Bay and 80 days for
Rehoboth Bay. No flushing estimates are
available for Little Assawoman Bay (Weston,
1993).
The inland bays are suffering from plant nutrient
enrichment (eutrophication) that causes unwanted
phytoplankton blooms with resulting declines in
light penetration and oxygen levels. These
changes in environmental quality have led to
eradication of submerged aquatic vegetation (sea
grasses) and to declines in desirable finfish and
shellfish. Major sources of these nutrients are
land runoff from intensive agribusiness
operations, intrusion of nutrient-contaminated
groundwater from agricultural and domestic
sources, and sewage treatment plant effluents.
Overall, the inland bays are highly nutrient
enriched (eutrophic), especially in the tidal creeks.
Characterization efforts in the Chesapeake Bay
yielded a classification system for bay waters
based upon total nitrogen and total phosphorous
concentrations. Under that classification system,
the inland bays' combination of ambient total
nitrogen concentrations, generally in excess of
1 part per million (ppm), and total phosphorous
concentrations, generally in the range of 0.1 to
0.2 ppm, would rank the inland bays among the
most enriched of the 32 sub-estuarine systems of
the Chesapeake Bay. Based upon the Chesapeake
classification system, the middle and upper
segments of the Indian River estuary are more
enriched than any segment of the Chesapeake Bay.
Significant increases in tidal flushing rates over
the past 20 years may have mediated the
progression of advancing eutrophic conditions,
especially in the lower, higher salinity reaches of
the system (Weston, 1993).
For Rehoboth Bay, agriculture is the principal
source of nitrogen, but point sources are the major
source of phosphorus, almost all of which
originates from the Rehoboth wastewater
treatment plant (Cerco, et al., 1994). For Indian
River and Assawoman bays, the principal source
of both nitrogen and phosphorus is agriculture,
through the application of inorganic fertilizers and
manures. These practices, applied to the sandy,
permeable soils of the watershed, have resulted in
widespread contamination of the groundwater by
nitrates (Andres, 1994)!
Groundwater is a highly significant component of
freshwater flow into the bays. About 70 to
80 percent of total freshwater stream flow is
composed of groundwater discharge.
Groundwater also flows under the bay shores and
discharges directly into the bays. Nearly all of this
groundwater originates as precipitation in the
inland bays watershed (Andres, 1992).
A-3
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Historical Juvenile
Fish Survey Sites
in Delaware
Rehoboth Bay
Derickson and Price (1973)
Timmons (1995)
Jensen (1974)
D EA (1974)
3.4 6 7 10
Indian River 1
1
White Creek
Figure 1. Historical juvenile fish survey sites which were revisited during the CBJA. Site 8,17, and
23 could not be sampled due to lack of beach. .
A-4
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METHODOLOGY
Field Collection
During the CBJA, a beach seine survey of juvenile
fish in the Delaware coastal bays was conducted
monthly from July to September 1993 at 26 of 29
sites corresponding to those sampled in historical
studies. Three sites could not be sampled due to
lack of beach (Fig. 1), Two kinds of sampling
gear were used to be consistent with the historical
studies. Sites corresponding to those sampled by
Edmunds and Jensen (1974) or Ecological
Analysts (1976) were sampled with a 50-ft., nylon
haul seine of 0.25-in mesh with a 6-ft. by 6-ft.
center bag. Sites corresponding to those sampled
by Derickson and Price (1973) were sampled with
a 60-ft., nylon haul seine of 1-in stretch mesh with
a 6-ft. by 6-ft. center bag. Two sites that were
common to the stucjies by Derickson and Price
(1973) and Ecological Analysts (1976) were
sampled with the 60-ft gear only. At all sites,
seines were deployed by holding one end on shore,
towing the other end perpendicularly away from
shore, walking parallel to shore for 50 yards, then
sweeping the seine in a semicircular path towards
the shore. All fish collected were identified, and
up to 25 individuals of each species were
measured to the nearest millimeter.
bays, percent abundances for each species were
calculated based on the two summer months'
collections that most closely approximated the
CBJA 1993 collecting times and the Maryland
coastal bays' finfish investigations (Casey, et al.,
1994) in either June/July or August/September.
Because of possible differences in sampling gear
and intensity, no special attempt was made to
analyze differences in total abundance. Fish
species were ranked by percent abundance for the
summer season by aggregating two sampling
periods (June/My or August/September) for each
body of water sampled.
Data Analysis
Data sets for shore-zone fish were assembled from
original data sets where possible. Otherwise, data
summaries from reports, technical papers, and the
Delaware inland bays characterization document
(Weston, 1993) were utilized in the analysis. The
principal studies used in this analysis are shown in
Table 1. Original data sets were available only for
the Coastal Bays Joint Assessment (CBJA) for
1993 and Edmunds and Jensen for 1971.
In an effort to determine how shore-zone fish
community structure may have changed with time
and allow comparisons to Maryland's coastal
A-5
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RESULTS
Indian River Bay and Rehoboth Bay
Results from Derickson and Price (1973) are
shown in Figure 2 and indicate that for the
summer of 1968 the five most dominant fish
species in order of percent abundance were
Menidia menidia (30.6%), Fundulus majalis
(29,2%), Fundulus heteroclitus (20.2%),
Pseudopleuronectes americanus (7.6%), and
Anchoa mitchilti (4.6%) representing a total of
92.2% of the total shore-zone fish community.
The same authors (Derickson and Price, 1973)
report for the summer of 1969 (Fig. 3) that the
most dominant fish species were Fundulus
majalis (35.8%), Menidia menidia (22.0%),
Fundulus heteroclitus (21.3%),Bairdielta
chrysoura (9.1%), and Pseudopleuronectes
americanus (3.5%) for a total of 91.7% of the
shore-zone fish community. In 1992, Timmons
(1995) captured shore-zone fishes reporting
Menidia menidia (34.8%), Fundulus heteroclitus
(16,4%), Fundulus majalis (16.3%),
Pseudopleuronectes americanus (5.2%), and
Anchoa mitchilli (4.6%) for a total of 77.3% of
the shore-zone fish community (Fig. 4). In 1993,
the CBJA duplicated the Derickson and Price
(1973) and Timmons (1995) studies and reported
dominance in order of percent abundance to be
Fundulus majalis (49.4%), Fundulus heteroclitus
(31.2%), Cyprtnodon variegatus (3.1%), Mugil
curema (2.9%), and Leiostomus xanthurus
(1.9%) for a total of 88.5% of the shore-zone fish
community. In this case, the two Fundulus sp.
accounted for over 80% of the total (Fig. 5).
A-6
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CBJA
1993
Rehoboth-7 Stations
Lower Indian River~8
stations
60' x 6' Haul
Seine; 0.5" Square
Mesh
Indian River—7 Stations
50' x 6' Beach
Seine; 0.25"
Square Mesh
-150'
July, August,
September
Timmons&
Price
1992
Rehoboth--8 Stations
Indian River--
7 Stations
20' x 3'; 0.25" Str.
Mesh
•100'
June, August
Price &
Schneider
1991
Little Assawoman Bay-5
Stations
33' x 4' Seine;
0.25" Str. Mesh
-100'
Single Event-
June
DNREC
Rehoboth--8 Stations
1986-
1988
Indian River--
7 Stations
50' x 6' Beach
Seine; 0.25"
Square Mesh
-150'
Monthly
May-November
22DP&L
1974-
1976
Indian River—Millsboro
to the Inlet-7 Stations
50'x 6'Beach
Seine; 0.25"
Square Mesh
-150'
Semi-Monthly-
1974-1975;
Monthly-1975-
1976
Campbell
& Price
1973
White Creek-
8 Stations
25' Beach Seine;
0.25" Square
Mesh
-ISO-
Weekly
Edmunds &
Jensen
1970-
1971
Upper Indian River~9
Stations
50' x 6' Beach
Seine; 0.25"
Square Mesh
-220'
Monthly
Derickson
& Price
1968-
1970
Rehoboth~8 Stations
Indian River—
9 Stations
60' x 6' Haul
Seine; 0.50"
Square Mesh
-150'
Monthly
Pacheco &
Grant
1957
White Creek-
8 Stations
25' x 6' Beach
Seine; 0.25"
Square Mesh
-150'
Semi-Weekly
The rank and relative abundance of the top ten
shore-zone fish collected by seine in the above
studies are shown in Table 2. The average rank of
the five most abundant shore-zone fish in order
areFundulus majolis (1), Fundulus heteroditus
(2), Menidia menidia (3), Pseudopleuronectes
americanus (4), and Cyprinodon variegatus (5)
which allows members of the Cyprinodon family
to comprise
A-7
-------
Fundulus majalis
29.24
>
00
Fundulus heteroclitus
20.19
Pseudopleuronectes
americanus
7.57
Anchoa mitchilli
4.58
Other
7.07
Bairdiella
chrysoura
0.73
Menidia menidia
30.62
Brevoortia tyrannus (0.00)
Cynoscion regalis (0.02)
Anchoa hepsetus (0.00)
/4/osa spp. (0.00)
Figure 2. 1968 percentages of total fish captured in the inland bays.
-------
Fundutus heteroclitus
21.34
Anchoa mitchilli
0.33
Menidia menldia
21.97
Fundulus majalis
35.75
Pseudopleuronectes
americanus
3.51
Other
7.06
Bairdiella chrysoura
9.14
Cynoscion regalls (0.26)
Anchoa hepsetus (0.00)
>4/osa spp. (0.00)
Brevoortia tyrannus (0.00)
Figure 3. 1969 percentages of total fish captured in the inland bays.
-------
Fundulus majalis
16.26
Pseudopleuronectes americanus
_^^^^_ .17
Fundulus heteroclitus dBBi^^^J ^ Anchoa mitchilli
16.4 J&WS^^F .A 4.56
Other
18.39
„ . .. ... ,^^^^^^_^ Brevoortia tyrannus
Menidia menidia ^
34.76
Bairdiella chrysoura (2.75)
Cynoscion regalis (1.53)
Anchoa hepsetus (2.28)
X\/osaspp. (3.21)
Figure 4. 1992 percentages of total fish captured in the inland bays, DE.
-------
Cyprinodon variegatus
3.12
Other
9.71
Micropogonias
undulatus
1.84
Fundulus heteroclitus
31.24
Mugll curema
2.88
Leiostomus xanthurus
1.85
Fundulus majalis
49.36
Menticirrhus saxatilis (0.61)
M. men/d/a(0.81)
P. americanus (0.81)
Mt/flf// cephalus (1.15)
Figure 5. 1993 percentages of total fish captured in the inland bays, DE.
-------
three of the top five rankings for Rehoboth Bay
and Indian River Bay. . :
Upper Indian River
Edmunds and Jensen (1974) collected shore-zone
fish at 9 stations from the base of the Millsboro
dam on upper Indian River to the mouth of Island
Creek near the DP&L Indian River power, plant
In 1971, they found the dominant fish species to
beBrevoortfa tyrannus (69.6%), Fundulus
heteroclitus (8,5%), Pomoxis nigromaculatus
(6.8%), Menidia menidia (4.7%), and Leiostomus
xanthurus (3.3%) for a total of 92.9% of the fish
community (Fig. 6). In 1993, the CBJA :
duplicated this study and reported dominance in
abundance by percent to be Menidia menidia
(60.9%), Fundulus heteroclitus (21.7%), :
Fundulus majalis (8.9%), Morone saxatilis
(2.2%), and Leiostomus xanthurus (1.4%) fora
total of 95.1% of the shore-zone fish community
(Fig, 7). The 1971 study reported a number of
primarily freshwater species including
Notemigonus crysoleucas, Fundulus diapkanus,
Pomoxis nigromaculatus, and Esox nigger.
Lepomis macrochirus and Lepomis gibbosus
were reported both in 1971 and 1993, but in larger
numbers in 1971.
shore-zone fish population (Fig. 9). In 1971,
three of the top five species were freshwater fish
with Fundulus sp. comprising only 10.7%, while
in 1993 all were brackish/estuarine forms with the
two Fundulus sp. comprising a total of 61.6% of
the total assemblage.
White Creek
In 1957, Pacheco and Grant (1965) conducted a
shore-zone fish survey of White Creek (Fig. 10)
and reported that the dominant species in order of
percent abundance v/ereBrevoortia tyrannus ..
(32.5%), Menidia beryllina (19.5%), Menidia
menidia (18.2%), Fundulus heteroclitus (13.5%),
mdAnchoa mitchilli (5.9%) for a total of 89.6% ••
of the shore-zone fish community (Fig. 11).
Campbell (1975) duplicated the study 16 years i
later and showed that the dominant species
captured in WWte Creek included Menidia
menidia (39.7%), Fundulus heteroclitus (13.6%),
Leiostomus xanthurus (13.0%), Menidia
beryllina (11.6%), and Fundulus majalis (8.8%)
for a total of 86.7% of the shore-zone fish
community (Fig. 12). In 1957, the two Fundulus
sp. comprised 15.6% of the total assemblage, By
1973, that had increased to 22.4% of the total
assemblage. :
Base of the Millsboro Dam
Station 1 from the 1971 study by Edmunds and
Jensen (1974) was the most up-river station in
Indian River and, therefore, should experience the
lowest salinities. In 1971, the most dominant
species by percent abundance were Pomoxis
nigromaculatus (45.2%), Menidia beryllina
(19.2%), Fundulus diaphanus (10.7%),
Notemigonus crysoleucas (9.5%), and
Leiostomus xanthurus (7.4%) for a total of 92.0%
of the shore-zone fish community (Fig. 8). In
1993 (Versar, 1995), the dominant species at that
station were Fundulus heteroclitus (48.1%),
Morone saxatilis (16.9%), Fundulus majalis
(13.5%), Menidia menidia (9.9%), and Menidia
beryllina (5.2%) for a total of 93,6% of the total
A-12
-------
Sheepshead
Minnow
6 i 2.5
3.1
Spot
1.6
5 !
1.9
Silver Perch
0.7
9.1
2.8
6*
Atlantic Croaker
1.8
White Mullet
10
0.6
10
0.5
4 !
2.9
10
Rainwater Fish
1.2
Striped Mullet
0.8
7JL
1.6
Weakfish
10
1.5
Northern Puffer
7 ! 1.5
Indian River Bav
The only additional data for Indian River Bay are
from a study conducted by Ecological Analysts for
Delmarva Power and Light (Ecological Analysts,
1976). The study included seven shore-zone
stations spaced approximately equidistantly from
Millsboro Dam to Indian River Inlet (Fig. 1).
Original data were not available for this study.
The semi-monthly (74-75) data or monthly (76)
data were aggregated by year (74-75,75-76, 76)
and, therefore, are not directly comparable to the
two monthly summer collections selected from the
other studies. However, these data do provide
some insight into the shore-zone fish community
and are included in Table 3 for completeness. The
rankings of dominant species for White Creek
(1957 and 1973) and Indian River (1974-1976)
are strikingly similar (Table 3) and show that the
dominant species in order are Menidia menidia
(1), Fundulus heteroclitus (2),Brevoortia
tyrannus (3), Menidia beryllina (4), and
Leiostomus xanthurus (5).
A-13
-------
Brevoortia tyrannus
69.60 ^^^^^^^^^^KHH^ Menidia beryllina 2.1 B
Pomoxis nigromaculatus
6.77
Other 4.82
Menidia menidia 4.74
Fundulus heteroclitus 8.54
Pomatomus saltatrix (0.34)
Fundulus majalis (1.12)
Notemigonus crysoleucas (1.42)
Fundulus diaphanus (1.64)
Figure 6. 1971 percentages offish captured In upper Indian River, DE.
-------
Menldia menldia
60.91
Leiostomus xanthurus
1.36
Fundulus majalis
8,88
Mug// spp.
4.01
Other
0.35
Fundulus heteroclitu$
21.73
Morone saxatllis
2.18
Perco f/ovescens (0,04)
Goblosomo bosc (0.09)
Lepomis macrochirus (0.09)
Fundulus dlaphanus (0.09)
Figure 7. 1993 percentages offish captured in upper Indian River Bay, DE.
-------
Pomoxls nigromaculatus
45.17
Lelostomus xanthurus
7.36
Fundulus diaphanus
10.68
Notemlgonos
crysoleucas
9.52
Other
6.20
Fundulus heieroclitus
2.02
Menidia berylllna
19.19
Trlnectes maoulatus (0.40)
Morone'amerlcana (1.29)
Pomatomus sattatrlx (1.30)
Lepomls glbbosus (1.73)
Figure 8. 1971 percentages of total fish captured in the base of Millsboro Dam, Indian River, DE.
-------
Menldla beryff/no
5.19
Menidia menldla
9-87 Mqfcrra spp.
1.82
Fundulus heteroclitus
48.05
Fundulus majalis
13.51
Morone saxatllis
16,88
Other
4.68
Perca f/cvescens (0.52)
Lepomls macrochlrus (1.03)
Lelostomus xanthurus (1.03)
Fundulus dtaphanus (1.03)
Figure 9. 1993 percentages of total fish captured in the base of Millsboro Dam, Indian River, DE.
-------
Indian River Bay
KILOMETERS
0 .2 .4 .6 .8 1.0 _
Figure 10. White Creek, Delaware, with the eight sampling stations indicated. Inserts shows location
of White Creek relative to the Atlantic coast.
A-18
-------
Brevoortia tyrannus
32.
Menldla men/d/o
18.23
Lucania pan/a
.30
Anchoa mitchnii
.5.94
Other
7.08
Fundulus heteroclitus
13,49
Menidia berylllna
19.47
Mug// curema (1.04)
Cyprlnodon varlegatus (1.10)
Fundulus majalls (2.10)
Bo/rcfe/to chrysoura (2.54)
Figure 11. 195? percentages of total fish captured in White Creek, Indian River, DE.
-------
ro
o
Menidia menldia
39.7Q
Menldia
Mug// cephalls
8.01
11.58
Lelostomus xanthurus
12.79
Fundulus majalis
8.82
Other
5.47
Fundulus heteroclitus
13.63
Gambusia afflnls (0.26)
Fundulus dlaphanus (0.40}
Anchoa mltchllil (1.57)
Cyrplnodon variegatus (2.02)
Figure 12. 1973 percentages of ftsh captured in White Creek, Indian River, DE.
-------
?ir- '-Y^^,. -;.'.••*&**"• ... • j.T-Tgr,-',.,,'.,. • 7
.Rank
Atlantic Silversides
18.2
39.7
2 j 14.8
26.0
6.5
Striped Killifish
2.1
8.8
1.3
4.4
0.7
Mummichog
13.5
13.6
i 12.2
1 j 27.6
6.5
Menhaden
32.5
58.6
3.3
70.9
Bay Anchovy
5.9
1.6
2.9
2.3
1.3
Sheepshead
Minnow
1.1
2.0
10
0.6
Spot
12.8
6 j 2.6
25.6
10.3
Silver Perch
2.5
Bluefish
9 j 0.7
Golden Shiner
8 !
1.4
Gizzard Shad
1.2
White Perch
A-21
-------
DISCUSSION
One way of attempting to examine trends in fish
populations over time in the Delaware's inland
coastal bays is to compare the composition for the
earliest records in the area with current
compositions. For White Creek, the earliest
record (1957) and three representative studies
conducted in 1968,1973, and 1993, there seems
to be a significant shift in the fish fauna!
dominance as shown in Tables 2 and 3. These
shifts are summarized below:
Rank
1
2
3
4
5
6
7
8
9
10
1957 -
Menhaden
Tidewater Silversides
Atlantic Silver-sides
Mummichog
Bay Anchovy
Rainwater Fish
Silver Perch
Striped Killifish
Sheepshead Minnow
White Mullet
'. •' "' . 1968 •••'.>•
Atlantic Silversides
Striped Killifish
Mummichog
Winter Flounder
Bay Anchovy
Sheepshead Minnow
Northern Puffer
Rainwater Fish
Silver Perch
' White Mullet
.•-•••'^•.•^•.-•-iMvt.^-.:
Atlantic Silversides
Mummichog
Spot
Tidewater Silversides
Striped KitUfish
Striped Mullet
Sheepshead Minnow
Bay Anchovy
Banded Killifish
Top Minnow
^^^Ow^^'^-^r-;
Striped Killifish
Mummichog
Sheepshead Minnow
White Mullet
Spotfi
Atlantic Croaker
Striped Mullet
Atlantic Silversides
Winter Flounder
Kingfish
During the past 36 years, it appears that
dominance has shifted from juvenile menhaden,
tidewater silversides, and bay anchovy to
Fundulus sp. and Sheepshead minnow. Basically,
the general impression is that the Family
Cyprinodontidae, which includes the killifish and
Sheepshead minnow, are becoming progressively
more dominant with time, while menhaden, bay
anchovy, and tidewater silversides are declining in
dominance. Of these, the ktllifishes and
silversides are year-round residents, while the
anchovy and menhaden are warm-water migrants
(Weston, 1993). Thornton (1975) reported that
the kUlifish and sheepshead minnow have strong
tolerances to low oxygen while menhaden and bay
anchovy are quite sensitive to low oxygen. Based
on the literature and his own research, Thornton
(1975) constructed a classification of estuarine
fish based on their sensitivity to low oxygen. For
the dominant fishes encountered in this study, they
are listed below in order of sensitivity:
A-22
-------
W^P^^i^^^P^^^^
Most Sensitive
'
Least Sensitive
^••'*£^jffifti?':^£?s tf^v-'-v
Brevoortia tyrannus
Menidia menidia
Anchoa mitchilli
Mugil cephalus
Bairdiella chrysoura
Leiostomus xanthurus
Cyprinodon variegatus
Fundulus heteroclitus
Fundulus majalis
»>&*.*: •.f+^'^^ .:.<^-^t
Atlantic Menhaden
Atlantic Silversides
Bay Anchovy
Striped Mullet
Silver Perch
Spot
Sheepshead Minnow
Mummichog
Striped Killifish
Although Anchoa mitchilli, the bay anchovy, was
not included in the original list by Thornton
(1975), he mentions that it is extremely sensitive
to being held in captivity and dies within a few
minutes in tanks or buckets, suggesting a very low
tolerance to hypoxic stress; i.e., it would probably
rank with the Atlantic menhaden and Atlantic
silversides as being very sensitive. Thornton
updated the ranking to include the bay anchovy as
shown above and as reported in Daiber, et al.
(1976).
Water Quality Considerations
The nutrient inputs to the inland bays affect the
abundance and distribution of bay life. The
microscopic floating plants (phytoplankton) are
most prolific (as measured by chlorophyll
concentrations) in the portions of the estuary
closest to nutrient sources (e.g., in the upper and
middle portions of Indian River Bay), while
Rehoboth Bay generally represents an inter-
mediate level of ambient nutrients and chlorophyll
concentration, while the area nearest Indian River
Inlet has the lowest concentrations of both. The
same relationship is seen in the clarity (turbidity)
of the water, with the upper portions of the
tributaries having the most turbid water and the
areas flushed near Indian River Inlet having the
least turbid water. Turbidity also changes
seasonally, with clarity of the water generally
improving after Labor Day and lasting until about
Memorial Day. The most turbid water in all three
bays is seen during the summer season and
probably results from a combination of biological
effects (increased phytoplankton and microbial
growth) and physical effects (boat traffic)
(Ullman, et al., 1993).
Secchi depths in upper Indian River now average
about 50 cm year-round, but may be as low as
10 cm during summer months when extremely
high chlorophyll concentrations (in excess of
lOOug/L'1) occur in the mesohaline and tidal creek
portions of the river (Ullman, et al., 1993). Based
upon the EPA Chesapeake Bay classification
system, the middle and upper segments of Indian
River estuary are more enriched than any segment
of the Chesapeake Bay (Weston, 1993) and very
likely any portion of the Maryland coastal bays.
Submerged Aquatic Vegetation
A major worldwide decline of seagrass beds
occurred in the 1930s and affected the Chesapeake
Bay and the Delmarva Peninsula (Delaware,
A-23
-------
Maryland, and Virginia). While many areas
revived from the decline, the inland bays of
Delaware never recovered. Eelgrass, Zostera
marina, once present in the inland bays in the
1920s has been seen sporadically in small
quantities, but has not been verified since 1970.
Transplanting of seagrasses has been unsuccessful
in Delaware, probably due to high levels of
suspended chlorophyll, increased turbidity, and
high levels of nutrients (Orth and Moore, 1988).
The combination of excessive nutrient levels and
high turbidity appears to eliminate the growth of
submerged aquatic vegetation (SAV) such as eel
grass (Zostera marina) in the inland bays. This
probably has significant ecological effects,
because SAV is desirable habitat for a variety of
finfish and shellfish and is food for certain types
of waterfowl, although the habitat function may be
provided, to some extent, by attached benthic
algae (seaweeds) (Timmons, 1995). The
seaweeds probably also play a role in sequestering
excess nutrients during the summer, but we have
evidence that extremely high levels of nutrients
and turbidity have a degrading effect on the
seaweeds as well, especially in the upper portion
of Indian River Bay (Timmons, 1995).
Orth and Heck (1980) found that the dominant
fish species in Chesapeake Bay eelgrass meadows
v/emLeiostomusxanthurus (1), Sygnathus fiiscus
(2),Anchoa mitchilli (3), Bairdiella chrysoura
(4), and Menidia menidia (5). By contrast,
Fundulus heteroclitus andF. majalis ranked 9th
and 43rd in eelgrass meadows, respectively.
Habitat Loss through Salinity Changes
The aquatic habitats of the inland bays have been
significantly modified during the last few
hundreds years. The most significant impacts
have occurred as a result of the stabilization and
deepening of Indian River Inlet, which resulted in
a dramatic change in the bays' complexion. Since
the early 1930s, the bays have progressed from an
almost totally freshwater, landlocked system to a
marine-dominated estuary—all within 60 years.
The most dramatic change has occurred since the
early 1970s when the inlet depth eroded from
20 feet to depths in excess of 90 feet. The
resulting increase in the volume of highly saline
ocean that was allowed to pass with each tidal
cycle and the accompanying increase in tidal range
have had a profound'impact on the habitats and
living resources of the inland bays (Weston,
1993).
Of particular importance is the reduction (almost
total loss) of the tidal freshwater portion of the
inland bays. The establishment of dammed mill
ponds and the dredging of the upper portions of
tidal tributaries, thus allowing the extended
upstream progression of the saline tidal wedge,
coupled with the increased salinity of the bays, has
virtually eliminated breeding and nursery habitat
for anadrbmous fish once common to the inland .
bays. Striped bass, shad, and various herring, to
name a few, were once common to the bays and
have now virtually disappeared due to major
losses of mis high-value habitat Many of those
few upper tributary areas that could still function
as spawning and nursery fisheries habitat have
been channeled through coarse, woody habitat for
the purpose of water drainage and small-boat
navigation, yielding streams sterile of habitat
structure necessary for protective cover (Weston,
1993). "••"
Table 4 shows the increases in salinities that have
occurred since the late 60s and early 70s at the
uppermost stations in Indian River based on
Edmunds and Jensen's 1971 data compared to the
1993 CBJA. A comparison of the dominant fish
captured in 1971 in upper Indian River (Fig. 6)
and at the base of the Millsboro dam, (Fig. 8) with
fish captured in 1993 at the same locations (Figs.
7 and 9) shows a distinct shift from a
predominantly freshwater assemblage in 1971 to a
more brackish fauna in 1993 dominated primarily
by two Fundulus sp. ,
A-24
-------
7.5
7.8
10.7
14.1
12.5
11
7.5
12
11.2
8.0
17.0
7.5
17
13.5
12
16
19
15.4
21.7
10
21
17.5
17.5
19
18.8
21.2
21.9
11
23.5
22.5
20
23.5
20.2
23.6
24.0
10
11
24
25
21.5
24
22.8
26.0
24.8
11
13.5
25
25.5
24
25
24.5
26.3
26.3
Data taken from line graphs in Jensen report for EPRI (Edmunds and Jensen, 1974).
MD.64
..34'
54
30-31
10
49
11
40
Markers are mid-channel.
Of special note is the appearance in 1993 of a
strong year class of young-of-the-year striped bass
(Morone saxatilis) not reported in these bays in
significant numbers in any previous study
(Pacheco and Grant, 1965; Derickson and Price,
1973; Edmunds and Jensen, 1974; Campbell,
1975). The only interpretation that is offered is
that the great recent success of the striped bass
population in the Chesapeake Bay is allowing an
expansion of the spawning stock into Delaware's
inland coastal bays. As evidence for a one-time
recent occurrence of striped bass, Timmons
(1995) surveyed the shore-zone fish of Indian
River and Rehoboth Bay in 1992 duplicating the
1969-70 study of Derickson and Price (1973) and
found no striped bass (Morone saxatilis).
A-25
-------
MARYLAISfD*S COASTAL BAYS
SHQRB ZONE FISH COMMUNITIES
Cecelia C, Linger, James F. Casey, Steve Doctor, Alan Wesche
.Marylattd Department of Natural Resources
.. .'January 1996
INTRODUCTION
The shallow waters of Maryland's coastal bays have Historically supported large populations of juvenile
finfish and shellfish; adults of many species, of fish are also seasonally common. Atlantic croaker, bluefish,
spot, summer flounder, weakfish, shark, blue crab and hard clam are important bom recreational and
commercial species which use habitats of the coastal bays. Over 115 species of finfish, 17 species of
mollusks, 23 species of crustaceans and countless foraging/grazing organisms frequent these bays (Casey et
ah, 1991,1992,1993). Since 1972, Maryland's Department of Natural Resources has sampled the coastal
bays, supplying data for environmental reviews and resource, management Current data on fishery stocks in
Maryland's coastal bays are important for several reasons: (1) Many species which use this habitat (bluefish,
butterfish, croaker, spot, American eel, summer flounder, scup, sea bass, weakfish, spotted sea trout, red and
black drum, white perch, blue crab and horseshoe crab) are the subjects of interstate and/or state management
plans, (2) development is increasing, and (3) important fisheries are dependent on production from this area.
Human population growth and watershed development are encroaching on the coastal bay system. Over the
next 20 years, local human population levels are expected to increase by 28%, and most of the development
will be along the shoreline. Survey data can be used in evaluating impacts of specific developments and
tracking ecosystem health over the long term (Citizen's Agenda, 1990). The value of the local commercial
and recreational fisheries is quite significant In 1992,15.8 million pounds of finfish and shellfish worth 7,7
million dollars were landed in Ocean City, This catch represented 28% of the weight and 21% of the value of
Maryland landings. Most of the region's commercial and recreational fishery landings were composed of
estuarine-dependent species (Citizen's Agenda 1990) such as summer flounder, weakfish, croaker, and sea
bass. During 1985, the last survey year where coastal recreational catch data could be separated from total
state recreational catch data, approximately 378,000 recreational fishing trips caught 1.1 million fish in
Maryland's coastal waters (NOAA/NMFS, 1986). Trip related expenditures of these fishing trips was $19.1
million (O.S.F.&W.S..1989).
Information from annual catch data and analysis have been of considerable value to a number of
organizations and agencies. Among those requesting data are the ASMFC Spot and Atlantic Croaker
Workshop, ASMFC Weakfish Technical Committee, ASMFC Summer Flounder Technical Committee, Mid-
Atlantic Fisheries Management Council, MDNR.Water Resources, Tidal Wetlands Division, U.S. Fish and
Wildlife Service, Environmental Protection Agency, National Park Service, U.S. Corps of Engineers, Versar
Inc., Virginia Institute of Marine Sciences, University of Maryland CEES, Delaware DNREC, offices of
Maryland state delegates, U.S. Congressmen and Baltimore Sun and Washington Post newspapers.
Educational seminars were also conducted with University and Elementary school students.
-A-26
-------
THE SETTING IN MARYLAND
Maryland's coastal bays (Fig. 13) are contained
within a single Maryland county and consist of six
interconnected water bodies- St. Martin River and
Assawoman, Isle of Wight, Sinepuxerit, Newport,
and Chincoteague Bays- as well as a number of
smaller tributaries. Combined they have a total
water surf ace area of 140.6 square miles. The
watershed however, is only about 205 square
miles in size, primarily due to the proximity of the
Pocomoke River to the west The total length of
the bays and watershed between the Virginia and
Delaware lines is about 35 miles. The land is low,
sandy, and generally poorly drained. Extensive
Type 17 wetlands (Spartina) border much of the
coastal bays. The coastal bays have been
estimated to contain 92% of the state's inventory
of this wetland type.
Geomorphology
The coastal bays and watershed are underlain by
three distinct geologic formations:
1. Sinepuxent formation- dark, poorly
sorted, silty, fine to medium sand with
thin beds of peaty sand and black clay.
2. Ironshire formation- pale yellow to white
sand and gravelly sand.
3. Beaverdam formation- pale coarse
gravelly sand with thin local beds of dark
gray clay containing peaty material.
Soils of the watershed are predominately of the
Fallsington-Woodstown-Sassafras association.
These are level to steep and poorly drained to well
drained with a dominant sandy clay-loam subsoil.
Smaller regions of other soil types exist here,
characterized by poor drainage and a silty clay-
loam subsoil. There are ten known aquifers that
may impact the watershed with the Quaternary
aquifer being the most important source of fresh
water. It is recharged by precipitation over a
broad area. Some of these aquifers contain salt
water. Contamination of existing aquifers with
salt water has taken place in limited areas due to
dredging or excessive fresh water withdrawal.
The water table is generally within 25 feet of the
surface with basement rock formations found in
excess of 7,500 feet deep.
Hydrography
Seven notable streams are tributaries to the
coastal bays, with the St Martin River, accounting
for 62% of the total drainage area for the upper
two bays, being the primary one. The coastal bays
are connected to the Atlantic Ocean by an inlet at
Ocean City and an inlet at the southern terminus
of Chincoteague Bay in Virginia. The bays are
shallow, generally less than six feet in depth, with
the greatest depths in the marked navigation
channels. Shoaling is common in many areas of
the bays, reducing depths to only one to three feet
Mean salinities for the areas sampled by Maryland
DNR vary from 25 ppt to 30 ppt during the
summer. However, in Chincoteague Bay, the slow
water exchange rate can cause evaporation to
increase salinity to as much as 35 ppt. Circulation
patterns and tidal ranges are dependent on wind
conditions and proximity to the inlet. Currents
near the inlet can reach five knots with tidal
amplitudes of three to four feet The currents
rapidly drop off with distance from the inlet.
Historically, the barrier island is susceptible to
interdiction by severe storms. Since the 17th
century, more than fifty hurricanes and heavy
storms have hit Maryland's coast leaving more
than eleven inlets in their wakes.
A-27
-------
Assawoman Bay
Isle of Wight Bay
Atlantic Ocean
Figure 13. Historical finfish seine sites for Maryland's inland bays.
A-28
-------
Sediments
Coastal bay sediments consist primarily of clay-
silts along the western edge, grading through
sand-silts in mid-bay to sand along the eastern
edge. Numerous lenses of varying size of the clay-
silts occur within the east side sands. In most
upper coastal bay sediments, carbon, nitrogen and
sulfur are generally within expected ranges for
marine sediments. Metals are also generally within
expected ranges although copper and zinc levels
are slightly elevated.
The area is biologically diverse. Many of the
marshes are classified as Type 17 wetlands with
additional species dominating the drier ecotones.
Over 11,000 acres of low and high salt marsh
have been estimated for the coastal bays.
Submerged aquatic vegetation (SAV) is common
and gradually increasing along the eastern sides of
the lower two bays but somewhat uncommon and
static in the upper two bays. The lack of SAV's in
the upper bays can be due in part to over 25 years
of dredge-and-fill activity and resultant changes
along the bayside of Ocean City. In 1981, over
157 species of benthic invertebrates representing
five phyla were sampled in the bay sediments
(Casey and Wesche, 1982). Species richness and
abundance varied both temporally and spatially.
Diversity and density declined towards late
summer and with proximity to the inlet. Generally,
diversity and density were higher along the
western edges of the bays with clay-silts being the
preferred substrate. However, stressed habitat
severely limited or eliminated these benthics.
Over 115 species of finfish have been identified.
Most of these are estuarine-dependent,
particularly juvenile game fish such as flounder,
sea trout, spot, croaker, bluefish, striped bass, eel
and sea bass (Casey et al., 1991, 1992, 1993).
The coastal bays are recognized as a valuable
breeding and nursery habitat for game species as
well as the forager/grazers (Figs. 14 and 15).
The bays are an important area for more than 200
species of birds. More than 11 species actively
feed on emergent shoals while many more use the
area for breeding, feeding, staging and wintering.
Several are listed as threatened or endangered
(Citizen's Agenda, 1990). Diamondback terrapin,
which have never fully recovered from excessive
harvest in the early 1900's, use small, protected
sandy beaches within the wetlands to deposit eggs,
spending the balance of the year foraging around
the more isolated wetlands. Protected turtles such
as the Atlantic Loggerhead and Leatherback have
been observed in the upper two bays. A variety of
mammals including raccoon, muskrat, otter and
harbor seals use the bays for feeding and/or
breeding.
Land Use in the Watershed
The western side of the bays are primarily rural
but with rapidly accelerating housing and strip
development on the upper two bays. The eastern
side represents extremes, with 25 miles of
Assateague Island maintained in its natural state
by the National and Maryland statepark systems
and to the north, ten miles of Fenwick Island as
Ocean City, a heavily developed resort, holding as
many as 240,000 visitors on a summer weekend.
In 1990, it was estimated that 43 developments of
various kinds were under construction or
completed (Citizen's Agenda, 1990). Currently, at
least eight more are in the planning stages or
under construction. Much of this development and
construction is taking place on land recognized
since 1977 as a flood hazard area. The rural areas
of the watershed are devoted to lumber
production, agriculture, and the chicken industry.
Two wildlife management areas are within the
watershed as are six sewage treatment plants of
varying capacity; five of which empty into the
coastal bays.
A-29
-------
Boy Anchovies (3*]
Anchoa mltehllll
Holfboak (71)
Mpetfiamaftus untfasclatvs
Atlantic Needlefish (9")
Strongyturo marina
Striped KJIHfish (to 8')
Fundulus majalls
Minnow (to 4*]
Cyprinodon vcrifegaftf
Banded KllllRsh (to A'/f]
Fundulus dlaphanus
Ralnwalw (Qtimifi (1^
Lucanla parva
Mummlchog (to 5")
fundulus heteroclltus
Figure 14. Common shallow water species present in the Delaware and Maryland inland bays
(Lippson and Lippson, 1984).
A-30
-------
a
Figure 15. Common benthic species in Maryland's inland bays: a) oyster toadfish, Opsanus tau; b)
skiUetflsh, Gobiesox strumosus; c) striped blenny, Chasmodes bosqulanus; d) naked goby, Gobiasoma
bosci\ e) northern puffer, Sphoeroides maculatus', f) northern searobin, PrinoCus carolinus; g) summer
flounder, Paralichthys dentatus; h) hogchoker, Tinectes maculatu (White, 1989).
A-31
-------
Perceived Stressors on the System
Rapid growth of housing and strip developments
and the resultant associated problems of sewage,
stormwater runoff, boat traffic and dockage
demands, and service and solid waste demands are
the primary stresses on much of the coastal
waters. Bulkheading eliminates wetlands and
shallow water habitats and creates unstable
bottom conditions. Dredging and dead-end canal
developments create unusable or detrimental
habitat Discharge of untreated and treated sewage
from five sewage treatment systems, landfill
leachate, poultry plant and agricultural runoff, and
aging septic systems add to the problem.
Currently, Turville/Herring Creeks and the St.
Martin River have been closed to shellf ishing
from coliform contamination since 1975 and
Johnson Bay since 1966. Generally, it is
acknowledged that seasonal patterns for dissolved
nutrients, chlorophyll-a and dissolved oxygen are
similar to other healthy high saline coastal bays.
However, current water quality data is distinctly
inadequate at detecting short and long term trends
in toxic contaminants and water degradation.
Commercial and recreational fishing contribute
considerably to the local economy, bringing in an
estimated total of 427 million dollars annually to
their respective industries. Currently however,
over 18 species of finfish and shellfish are
undergoing state and/or federally mandated
management measures because their populations
are near, at, or below sustainable harvest levels.
Contributing to this problem have been the
alteration, degradation, and/or elimination of
quality habitat.
six-minute trawls were made at 20 fixed sites each
month between April and October, 1989-1994.
Single quarter-circle seine hauls were made at 19
fixed sites around the perimeter of the coastal
bays in tributaries in June and September, 1989-
1994. Between 1972 and 1988, both seine and
trawl were made at the same sites in various
degrees of frequency in this time period (Table 5).
Finfish data collected at each site included species,
number, total length (TL, mm), salinity,
temperature, wind and weather conditions and tide
state. .
METHODOLOGY
FjeldCollection
Fishes were sampled with a 4.9 m (16 ft.) semi-.
balloon otter trawl in areas over 1.0 m deep and a
30.5 m X 1.8 m X 6.4 cm (100 ft X 6 ft X .25 in)
bag seine in areas less than 1.0 m in depth. Single
A-32
-------
Table 5. Sampling frequency for the Maryland inland bay finfish survey by year (top row) and month (subsequent rows) for each site (left-most column).
SITE
2
3
14
13
18
IS
16
17
7
1
4
5
6
11
12
9
8
10
m$
ki/J*
8
6; 8
6; 8
6; 8
7
9
6
6; 8
8
PSIP
fiilfSik*
6
6; 8
8
7
8
7
7; 8
6;7;8
6
6; 8
6
7
6
7; 9
6
^SHsffc^.
7; 8
7
8
7
8
7
7; 8
7; 8
7
7
6
'£>*!&>'
^7* l
saSK»
6; 8
5; 8
8
8
6
6
7
7
7
6
5; 8
7
7
tn
l>t'VT'f'~r
7
7
7
6; 8
7
7
7
7
7
6
6
6
7
7
-$m
i£*?*!
6; 8
6; 8
6
6; 8
6
7
7
7
6
6; 8
6; 8
7
7
^5*#<»
i*!fe»
7
7
6; 8
8
6; 8
7
/'
7
7
7
7
6
6; 8
8
8
8
(s:*;*
S^m
6
7
6; 7
6
6; 8
6; 8
6;8
7
7
7
7
7
7
7
7
7
iis
8
6; 10
8
9
9
9
9
8
8
9
9
^srersss
&$%&
7
7
7; 10
7; 9
7
7
7
7
7
7
?fP
'"flB
7
7
7
7
8
8
8
8
7
7
7
7
7
7
7
7
7
m
8
7; 8
8
8
7
«
10
10
10
10
;'|P
&8?«ii
7
7
8
7; 8
7; 8
8
8
7; 9
7
7
7
7
7
8
8
8
8
8
* "-V^i?;
»
7; 9
7:9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7:9
7; 9
7
7
7; 9
7; 9
7; 9
7:9
7; 9
7; 9
»-3V**
***S.
8; 9
8; 9
8; 9
8; 9
8; 9
8; 9
8; 9
8; 9
8; 9
8; 9
8; 9
8; 9
8; 9
8; 9
8; 9
8:9
8; 9
8; 9
,'S!7*-!i*.
«;9Cfe,
ii,:--- •. ••*•-.
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
to
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
Ste
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
7;9
7; 9
7; 9
7; 9
7; 9
7; 9
7; 9
lip
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
9
6; 9
6; 9
m
6; 9
6; 9
6; 9
6;9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
6; 9
A-33
-------
Total effort and number of species collected
annually were tested for linear or curvilinear
(quadratic) relationships with regression analysis.
Residuals of regression of number of species and
effort were tested against time for trends. Effect of
sampling effort on number of species collected
was allowed for by using the residuals of the
linear regression of sampling effort against
number of species. Studentized residuals and
Cook's D were examined to diagnose outliers or
highly influential observations. Plots of residuals
against predicted values and residuals against year
were examined for the need for additional terms or
sequential trends, respectively.
In order to make comparisons with the fish
community structure of Delaware, the data from
the Maryland trawl effort was dropped from
analysis. Also, seine site 19, which is located in
Ayers Creek, a tributary of Newport Bay, was
dropped from analysis due to the great difference
in salinity at this station (0 ppt) compared to the
rest of the sampling sites (25-35 ppt). From the
resultant 18 seine sites (Figure 13), percent
abundances for each species were calculated for
each year over the entire system and ranks were
assigned. Mean rank and mean percent abundance
were also calculated for each species for five-year
increments aggregated over the Assawoman/Isle
of Wight/St Martin River complex (seine sites 1-
7) and Chincoteague Bay (seine sites 13-18) in
order to compare the fish community structure
within these two subsystems.
RESULTS
From within the coastal bays, a total of 101,291
individuals representing 107 species of fish and
invertebrates was collected in trawl and seine
samples between April and October, 1993
(Attachment). Some of the important shallow
water and benthic species are illustrated in Figures
14 and 15, respectively. Sampling effort was the
same in both 1992 and 1993; however, there was
a significant increase of 93% in numbers caught
and a 21% increase in the number of species from
1992 to 1993. Abundance of the 14 majpr species
of foragers and grazers (Table 6) showed a 63%
increase over 1991 levels and comprised 90% of
the total 1993 finfish catch. Virtually all major
game fish were below 1991 levels.
The linear regression of total number of species
collected against sampling effort was significant
(r2 = 0.60, p=< 0.001). The time trend of the
residuals of the previous regression was
significant (r2 = 0.32, p =< 0.006), indicating that
the number of species has been increasing slightly
in the coastal bays during 1972-1993.
Northern bays versus Chincoteague Bay
The fish community structure for the northern
bays (represented as mean rank and mean percent
abundance) for Assawoman/Isle of Wight/St.
Martin River complex (seine sites 1-7) and for
Chincoteague Bay (seine sites 13-18) are shown in
Table?. For the years 1972 to 1976, the five
species with the highest mean ranks (with mean
percent abundance over the same time frame to
give an impression of the strength of their
presence) for the northern bays were (1)
Leiostomus xanthurus (25%), (2) Menidia
menidia (35%), (3) Brevoortia tyrannus (26%),
(4) Fundulus heteroclitus (1.7%), and (5)
Fundulus majalis (3.6%). By the 1989 to 1993
time frame, the picture changed such that the
ranking was (1) Menidia menidia (32%), (2)
Anchoa mitchilli (11%), (3) Bairdiella chrysoura
(8%), (4) Mugilcurema (11%), and (5)
Leiostomus xanthurus (11%). Over the same two
time frames, the Chincoteague Bay went from a
species ranking of (1) Brevoortia tyrannus
(33%), (2) Menidia menidia (33%), (3) Anchoa
mitchilli (15%), (4) Leiostomus xanthurus (9%),
and (5) Strongylura marina (0.6%) to (1)
Menidia menidia (25%), (2) Anchoa mitchilli
(20%), (3) Brevoortia tyrannus (33%), (4)
Bairdiella chrysoura (6.5%), (5) Leiostomus
xanthurus (5.1%). Over the entire twenty years,
the four most dominant species were Menidia
menidia, Anchoa mitchilli, Leiostomus
xanthurus, and Brevoortia tyrannus with the fifth
most dominant species being F. heteroclitus in
A-34
-------
Chincoteague Bay and F. majalis in the northern
bays. The mean number of species and the mean
total catch over the five year increments were
always significantly larger for the northern bays
than the Chincoteague Bay although the effort is
comparable.
A-35
-------
Table 6. Species of foragers and grazers comprising 90% of the total 1993 finfish catch.
SPECIES
BAY ANCHOVY
ATLANTIC
SILVERSIDE
SPOT
ATLANTIC
MENHADEN
ATLANTIC
HERRING
WHITE MULLET
SILVER PERCH
STRIPED
KILLIFISH
MUMMICHOG
NORTHERN
PIPEFISH
SMALLMOUTH
FLOUNDER
RAINWATER
KILLIFISH
NAKED GOBY
STRIPED
ANCHOVY
SUBTOTAL
SEINE CATCH
4,331
10^947
1,155
894
1
2,132
1,056
380
693
: 88
10 '
378 . ,
109
69
22,343
•• ^^jmiiiiiK
.-..•, -'>>•>/:— o - - A- «*•"£•; .••/ft:*"'- *•.•;**;•
20,249
27 •
1,118
23
1,893
1
184
o
.8
141 . .
20
55
60
15
23,794
24580
10974
2273
917
1894
2133
1240
380
.701
229
30
433
169
.84
46137
A-36
-------
Table 7. Mean rank and abundance for the top ten species of each year for the Assawoman/Isle of
Wight/St. Martin River complex (seine sites 1-7) and Chincoteague Bay (seine sites 13-18).
Species
1976-1981
MEAN RANK
<%OF TOTAL)
A/IW/S
CHINC
1989-1993
ME AN RANK
(%OF TOTAL)
A/IW/S
CHINC
Iff'3
Atlantic silverside
1(41)
4(10)
1(32)
1(25)
Atlantic menhaden
5(28)
1(43)
6(16)
3(33)
Spot
2(16)
3(12)
5(11)
5 (5.1)
Bay anchovy
3 (7.5)
2(31)
2(11)
2(20)
^w^^r-i,--
Striped killifish
8 (0.2)
9(1.1)
7 (1.0)
Mummichog
7 (1.5)
7 (1.4)
Striped mullet
4(1.8)
Atlantic needlefish
9 (1.3)
5 (0.2)
6 (0.8)
Summer flounder
7 (0.4)
6 (0.3)
10 (0.3)
Bluefish
9 (0.1)
Oyster toadfish
Northern pipefish
8 (0.6)
American eel
10 (0.1)
10 (0.1)
Sliver perch
3(8)
4 (6.5)
Inshore lizardfish
White mullet
10(1)
9 (0.6)
4(11)
Atlantic croaker
Striped anchovy
8 (1.0)
Weakfish
Sheepshead minnow
Southern stingray
8 (0.1)
A-37
-------
Species
Winter flounder
Mean # of Species
Mean Total Catch
1972-1976
.MEANRANK';
V:(?6OFTOTAU
A/IW7S
22
8635
CHINC .
13
2941
1976-1981
MEANRANK
(%OF TOTAL)
A/IW/S
6 (1.4)
18
18173
CHINC
16
3794
' riifewsl-^;
" MBANRANKijr
<%OFfC*A^ ^v
A/IW/S
, .'. -.(';" ^ ' •..
J'- 3*: ;;
: 11027
efflNc a
'- ^-'"- • ',- '>'.*•"
, .*, .-,.. .,....• ;,i
1 |?^1;"
: -MM?
1989-1993
MEANRANK
(%OF TOTAL)
A/IW/S
44
6370
CHINC
32
5376
^^^i^fl
>^;p*§^;RAWi«''£i[)i
?Bl*1^.ttWAt*j;"3
^4^:*4:^^
£ • . vi ":,.' -S-r i" ).<•-- ,^V.*:~y -v^ > uv
^-vVyW^;.^'^.
si'A/WfeS'^
r-!^*??^*
:^W
«.'?tK!'-1>"';V-i
Ifslfi
•.-&/••• 4 .«•
^Wtl
-:..:$•"••:.'.#&:&;
i, .* riisj;-*
£'T;>'ff:iS{.«l
:4.*4§*^l
-^:..-."\;-,-*WfrV
^*;|fe^
C-T:;.f-SrJKji:
;liii
Entire Maryland Coastal Bays
In 1972, the predominant species collected were
Brevoortia tyrannus (39.0%),Menidia menidia
(28.2%), Leiostomus xanthurus (25.3%),
Fundulus heteroclitus (4.6%), and Paralichthys
dentatus (1.4%) for a total of 98.5 percent of the
fish community (Fig. 16). By 1977, the dominant
species were Brevoortia tyrannus (35.7%),
Menidia menidia (30.2%), Leiostomus xanthurus
(\%.Wo),Anchoa mitchilli (l2.Z%),Mugil
cephalus (1.4%) for a total of 97.6 percent of the
fish community (Fig. 17). In 1982, the dominants
were the same except that F. majalis was the fifth
most dominant species replacing Mugil cephalus
at 1.2 percent of the total fish community (Fig.
18). By 1987, the dominant species were Menidia
menidia (87.5%), Anchoa mitchilli (3.6%), Mugil
cephalus (2.4%), Brevoortia tyrannus (2.3%),
and Bairdiella chrysoura (1.0%) for a total of
96.8 percent of the fish community (Fig. 19). In
1992, the dominant species were Brevoortia
tyrannus (37.4%), Menidia menidia (34.2%),
Bairdiella chrysoura (13.5%), Anchoa mitchilli
(2.9%), and Mugil curema (2.4%) for a total of
90.4 percent of the fish community (Fig. 20). In
1993, the dominant species were Menidia
menidia (48.5%), Anchoa mitchilli (19.1%),
Mugil curema (9.5%), Leiostomus xanthurus
(5.0%), znA Bairdiella chrysoura (4.3%) for a
total of 86.4 percent of the shore-zone fish
population (Fig. 21). Since 1989, the average
.rank of the top five dominant species is Menidia
menidia (1), Anchoa mitchilli (2), Brevoortia
tyrannus (3), Leiostomus xanthurus (4), and
Fundulus majalis (5). The ranking of the top five
dominants has essentially included the same five
species for the past 20 years.
Using five year means of ranks of species
determined by percent abundance, the same six
species are ranked in the top seven for the four
time periods calculated. In descending order of
their twenty year mean rank, these six species are
Atlantic silverside (Menidia menidia), Atlantic
menhaden (Brevoortia tyrannus), spot
(Leiostomus xanthurus), bay anchovy (Anchoa
mitchilli), striped killifish (Fundulus majalis),
and mummichog (Fundulus heteroclitus) (Tables
8-11). Striped mullet (Mugil cephalus), whose
average rank from 1972 to 1988 was between 6
and 7, dropped in average rank to 12 in the 1989
to 1993 time period. For the same time periods,
atlantic menhaden dropped from an average rank
of 1 to 3, summer flounder (Paralichthys
dentatus) dropped from 7.5 to 11, and northern
pipefish (JSygnathus fuscus) rose from 12 to 9
(Table 8-11).
A-38
-------
12 Others 0.51
Strongylura marina 0.0
Anguilla rostrata 0.11
Anchoa mitchilll 0.23
Fundulus majalls 0.25
Pomatomus saltatrix 0.35
Paralichlhys dentatus 1.37 -
Fundulus heteroclttus
4.60
co
CD
L xanthurus
25.28
Brevoortla tyrannus
39.0
Menidia menidla
28.20
Figure 16. Percent abundance of total catch for the top ten species caught in the Maryland seine effort for 1972.
-------
Mug// cephalus
1.42.
Menldia menldia
30.20
L xanthurus
18.14
Pleuronectes americanus
0.91
Strongylura marina
0.15
F. heteroclttut
0.35
11 Others
0.38
Brewoortia tyrannus
35.70
Anchoa mltchilli
12.23
Funduius majalls
0.18
Parallchthys dentatus
0.35
Figure 17. Percent abundance of total catch for the top ten species caught in the Maryland seine effort for 1977.
-------
Brevoortia fyrannus
22.23
21 Others 1.7'
P/euronectes amertcanus 0.31
Parallchihys denfcrfus 0.39
Cynosclon regalls 0,9:
Balrdlella chiysoura 1.03
Mugll cephalus 1. "T
Fundulus majails 1,21
Menldia menidla
11.85
Leiostomus xanthums
39.21
Anchoa mltchllll
19.89
Figure 18. Percent abundance of total catch for the top ten species caught in the Maryland seine effort for 1982.
-------
25 Others 0.75
Parallchlhys dentatus 0,2
Sfrongx/ura marina 0.4*
Fundulus majalls 0.50
Lelostomus xanlhurus 0.55
F. heteroclttus 0.68
Bairdlella chrysoura 1.01
Brevoortla fyrannus 2.32
Mug// cephalus 2,36
•Ancrtoo mltchllli 3.61
Menldla menidla
87.49
Figure 19. Percent abundance of total catch for the top ten species caught In the Maryland seine effort for 1987.
-------
43 Others 6.30.
Cyprlnodon variegatus 0.5
Anchoa hepsetus 0.56
Lelostomus xanthurus 0,57
Lucanla pan/a 0.77
Fundulus heterociltus 0.8
Mug// curema 2.3?
Aicftocf mttchlUi 2.94
Bairdiella chrysoura
13.51
Brevoorfla tyrannus
37.44
Menidia menldla
34.15
Figure 20. Percent abundance of total catch for the top ten species caught in the Maryland seine effort for 1992.
-------
Mug// curemo
9.45
Anchoa mltchllli
19.08
L xanthurus 5.03
Balrdlella c/i/ysoura 4.26
Fundulus heterocltfus 3.07
Fundulus majalis 1.69
lucan/q pa/veil.68
Membras martlnlca 1.60
49 Others 5.61
Menidia menldla
48.55
Figure 21. Percent abundance of total catch Tor the top ten species caught in toe Maryland seine effort for 1993.
-------
Table 8. Rank and relative abundance of the top thirteen shore zone fish collected by seine from the Maryland coastal bays 1972 - 1976.
Atlantic menhaden
39.0
5.5
28.8
43.8
46.2
1.6=1
Spot
25.3
18.7
27.5
10.7
27.2
2.6 = 3
Bay anchovy
0.22
4.8
6.8
22.9
4.8
4.8 = 4
Striped kffliflsh
0.24
3.6
5
5.3
10
0.43
5.7
6.4 = 6
Mummichog
4.6
14.4
3.1
1.4
2.1
5 = 5
Striped mullet
16
0.04
10
0.22
11
0.29
, 1.3
0.99
10 = 7.5
Atlantic needlefish
10.5
0.09
13
0.06
.20
0.03
7.
0.62
10
0.26
12.1 = 10
Summer flounder
1.4
11
0.19
0.61
11
0.34
15
0.06
10 = 7.5
Bluefish
0.35
19.5
0.03
10
0.30^
8
0.60
12
0.17
11.1 =9
Oyster toadflsh
17.5
0.04
16.5
0.04
24.5
0.02
18
0.04
23.5
0.01
20 = 13
Northern pipefish
13
0;07
16.5
0.04
24.5
0.02
14
0.09
23.5
0.01
18.3=12
American eel
0.11
19.5 0.03
14 0.11
15 0.07
15 0.06
14.5=11
Number of Species
22
33
28
31
26
28
Total catch
11359
30081
11395
10429
15532
15759
Table 9. Rank and relative abundance of the top thirteen shore zone fish collected by seine from the Maryland coastal bays 1977 -1981.
-------
•. • fay it- '
.-•' ' ':'.•*• .' r..* . n-» ...
• Species JS -*"• • T"-1 '•£.£
•„." '•.$&$,,%>:! :..-«$$
Atlantic silverside
Atlantk menhaden
Spot
Bay anchovy
Striped klllifish
Mummichog
Striped muUet
Atlantic needlefish
Summer flounder
Bluefish
Oyster toadfish
Northern pipefish
American eel
Number of Species
Total catch
«• W
1^4:
2
1
3
4
9
7.5
5
10
7.5
12
22
13
19
-'*.'% ''
30.2
35.7
18.1
12.2
0.18
0.35
1.42
0.15
0.35
0.08
NP
0.06
0.01
21
9257
1978
RAN
2
1
4
3
5
11
6
12
14
23
10
20
9
% .
3.94
91.4
1.0
3.2
0.15
0.02
0.05
0.02
0.01
0.00
0.02
0.00
0.03
24
101651
1979
RANK
1
4
3
2
7
5
9
11.5
6
14.5
16
13
11.5
%
36.8
10.3
12.8
29.1
0.26
9.4
0.15
0.10
0.32
0.06
0.05
0.07
0.10
26
18571
1980,;
RANK
2
1
3
5
4
9
7
6
10
26.5
13.5
11.5
13.5
• %
38.1
38.9
8.7
3.4
3.7
0.33
1.8
2.7
0.26
0.02
0.11
0.12
0.11
31
5453
1981
RAN
3
1
2
4
6
8
7
15
9
15
12
18
15
%
24.7
30.3
30.0
9.6
0.85
0.59
0.66
0.05
0.56
0.05
0.06
0.04
0.05
25
11434
1977-1981
AVG.RANK
2 = 2
1.6 = 1
3 = 3
3.6 = 4
6.2 = 5
8.1=7
6.8 = 6
10.9 = 9
9.3 = 8
18.2=13
14.7=11
15.1 = 12
13.6=10
25
29273
-------
Table 10. Rank and relative abundance of the top thirteen shore zone fish collected by seine from the Maryland coastal bays 1982 -1988.
Atlantic silverside
11.8
87.5
12.0
3 = 3.5
Atlantic menhaden
22.2
2.3
16.5
2.7 = 1.5
Spot
39.2
0.55
38.8
3 = 3.5
Bay anchovy
19.9
3.6
12.8
2.1 = 1.5
Striped killifish
1.2
0.50
3.7
6.3 = 5
Mumraichog
11
0.26
0.68
4.1
7.3 = 7
Striped mullet
1.2
2.4
11
0.40
6.7 = 6
Atlantic needlefish
13.5
0.20
0.49
12
0.36
11.5 = 8
Summer flounder
0.39
10
0.25
32.5
0.03
17.2=10
Bluefish
13.5
0.20
11
0.17
18
0.14
14.2 = 9
Oyster toadfish
19
0.09
15.5
0.05
20
0.10
18.2=11
Northern pipefish
18
0.10
12
0.10
25.5
0.07
18.5=12
American eel
22.5
0.04
21
0.02
36
0.02
26.5=13
Number of Species
31
35
53
40
Total catch
9700
18888
39108
22565
-------
Table 11. Rank and relative abundance of the top thirteen shore zone fish collected by seine from the Maryland coastal bays 1989 -1993.
Vi,--; T : : i ' ' '"-it :«':
.: -..,;•<;«£ -i'i-v.- '•! ! -3iJ!4ff».
$S^;*|v^'i$Sj
Atlantic silverside
Atlantic menhaden
Spot
Bay anchovy
Striped killiflsh
Mummichog
Striped mullet
Atlantic needlefish
Slimmer flounder
Bluefish
Oyster toadfish
Northern pipefish
American eel
Number of Species
Total catch
** J*B***ta~» ** ' ' •
T XtlPj'V - -
^:$W89 r •
.,£S3s
I
5
3
2
8
10
34.5
16
17
12
14.5
19
30.5
V%
30.4
4.77
16.0
29.8
1.0
0.69
0.06
0.40
0.35
0.59
0.41
0.27
0.07
51
7007
t ' 1990
': RAN
2
1
4
3
6
21
9
13
8
16
12
17
37
. :%'/|
16.7
53.0
6.3
14.7
1.0
0.10
0.45
0.31
0.50
0.16
0.33
0.16
0.01
44
18559
< ' 1991.
RANK
1
2
5
3
7
13
14
9
20
15
17.5
17.5
45
:%
27.6
21.3
7.2
12.5
1.9
0.96
0.69
1.7
0.22
0.53
0.24
0.24
0.02
57
10095
1992
RAN
2
1
8
4
22
6
42
13
15
32
24.5
27
45
%'.
34.1
37.4
0.57
2.9
0.31
0.89
0.02
0.43
0.39
0.07
0.17
0.11
0.02
53
20715
1993
RAN
1
10
4
2
7
6
22
17.5
22
24
13
15
11
% '
48.5
0.74
5.0
19.1
1.7
3.1
NP
0.31
0.13
0.12
0.43
0.39
0.53
58
22549
1989-1993
AVG.RANK
1.4=1
3.8 = 3
4.8 = 4
2.8 = 2
10 = 5
11.2 = 6
24.3 = 12
13.7 = 7
23.2=11
19.8 = 10
16.3 = 8
19.1=9
33.7=13
53
15785
-------
DISCUSSION
In general, the fish community structure of the
Maryland inland bays is quite stable over the
years. The Maryland inland bays might be seen as
an example of what type of structure there might
have been in Delaware's system before more
intensive development and nutrient enrichment
took place. In fact there is evidence of a slight
increase in species richness in the Maryland inland
bays over the past 20 years as proven by three
different investigators using three different
techniques (Casey et al., 1992,1994; Linder, pers.
comm.). Moderate disturbances in some systems
have actually promoted species diversity; and
hypothetically, the increase in species richness for
the Maryland bays might be attributable to
changing physical conditions such as increases in
land development, bottom currents, and nutrient
enrichment. As with the Delaware data, the shifts
in the community composition of the entire
Maryland system are summarized below:
Menhaden
Menhaden
Atlantic Silversides
Atlantic Silversides
Atlantic Silversides
Atlantic Silversides
Bay anchovy
Bay Anchovy
Spot
Spot
Striped mullet
White mullet
Mummichog
Bay anchovy
Menhaden
Spot
Summer flounder
Striped mullet
Silver perch
Silyer perch
Bluefish
Winter flounder
Mummichog
Mummichog
Striped killifish
Mummichog
Spot
Striped killifish
Bay anchovy
Summer flounder
Striped killifish
Rainwater killifish
American eel
Atlantic needlefish
Atlantic needlefish
Rough silverside
10
Atlantic needlefish
Striped Killifish
Summer flounder
Menhaden
During the past 20 years, the dominance has
shifted from Atlantic menhaden, Atlantic
Silversides, and spot to Atlantic Silversides, bay
anchovy, and Mugil spp. Unlike the Delaware
coastal bays system, Maryland has not seen the
degree of increase in cyprinodontids to a position
A-49
-------
within the top four ranks. However, in 1993 three
cyprinodontids are representing ranks 6 to 8,
which might indicate an early warning sign for the
future. The 1994 data (not shown in this report])
also represent a higher abundance of combined
Fundulus spp. than the average amount for this
sytem. However, attempting to make a conclusion
might be premature without more sampling.
Important game species, such as summer flounder,
bluefish, Atlantic croaker, and American eel, have
dropped from ranking in the top ten to record low
levels in the past 23 years of data collection. It
appears at this time that more planktivorous
species such as Mugil spp. and bottom feeders
such as silver perch have replaced them in the
rankings. In attempting to glean an idea of what is
happening within the system, it is important to
take into account the scope of the effort and the
natural variability in fish populations, as well as
the positive effects that nutrients might be playing
on the living resources. One might expect the
Chincoteague Bay, in its pristine state with an
abundance of wetlands, to have a more diverse
and abundant assemblage of fish. This hypothesis
does not hold true. In fact, it is the northern bays
and Newport Bay, both of which are affected by a
greater nutrient load, that have the more diverse
sites with large complements of fish species
(Table 8-11). In general, the Maryland system
does not appear to be under the degree the stress
as the Delaware system, which might indicate why
the Fundulus spp are not as dominant in the
Maryland system.
One of the more detrimental forces acting upon
the fish community in Maryland is the degree of
over-utilization of fisheries resources. The
population of summer flounder crashed in the
early 1990s and is showing some signs of a come-
back since restrictions have been placed on the
amount and size of their catch. Bluefish have
crashed all over the Atlantic Coast fishery and the
impacts of that can be seen in the Maryland
coastal bays data. Weakfish have declined over
the years as well, as have American eel which
itself is in jeopardy from encroaching development
in the northern bays in areas of elver concentration
up the smaller creeks.
Habitat loss is a concern in the upper bays of
.Maryland with the degree of development planned
for this area. It appears that the fish communities
of this system tend to aggregate at spots that
provide a good three dimensional structure and
have marsh areas within a close distance (<50
feet). With development comes a loss in the
surface area of healthy shallow water habitat with
dredge operations and canalization. Moderate
levels of nutrients might have a positive impact on
the faunal assemblage, but loss of habitat and
refuge has no positive effect.
CONCLUSIONS
Therefore, one can conclude that generally
speaking the Maryland coastal bays are dominated
primarily by Atlantic silverside, bay anchovy,
Atlantic menhaden, and spot, and not by Fundulus
majalis and Fundulus heteroclitus which is the
case in the Delaware coastal bays today. Indeed,
if one compares the earliest available Delaware
record for shore-zone fishes in Delaware Bay
(1959) with the Maryland coastal bays fish fauna,
they are strikingly similar. deSylva et al. (1962)
reported that the dominant shore-zone fish species
for the Delaware Bay were Menidia menidia
(53.0%), Bairdiella chrysoura (17.9%), Anchoa
mitchilli (15.1%),Brevoortia tyrannus (2.3%),
and Fundulus majalis (2.2%) for a tofal of
90.5 percent of the shore-zone fish community
(Fig. 22). Likewise, in 1957, the dominant
species in White Creek, a tributary of Indian River
Bay v/ereBrevoortia tyrannus (32.5%), Menidia
beryllina (19.5%), Menidia menidia (18.2%),
Fundulus heteroclitus (13.5%), and Anchoa
mitchilli (5.9%) for a total of 89.6% of
A-50
-------
Balrdlella chrysoura
17.94
Fundulus majalis
2.24
Cynosclon regalis 1.79
Menidla menidia
52.97
Aneftoo mltchilli
15.09
Bra/oorf/o tyrannus 2.31
Other 7.66
Angullla rosfrofo 1.40
Fundulus heteroclitus 0.97
'Morone americanus
8.40
'Mentlclrrhus saxatilis
0.64
Figure 22. Percent abundance of total catch for the top ten species caught in the share zone of the Delaware Bay.
-------
the shore-zone fish community (Table 3; Paeheeo
and Grant, 1965), Therefore, if one goes back in
history some 35 years, at least in Delaware's bays,
the shore-zone fish community strongly resembles
that of the less impacted Maryland coastal bays of
today.
The fish community dominance in Delaware's
coastal bays has shifted toward those species that
are more tolerant to low oxygen stress [Thornton
(1975) in Daiber, et al. (1976)] and which are also
more tolerant to salinity and temperature
extremes. There is also a strong possibility that
Fundulus sp. and Cyprinodon sp. are more
adaptable to eutrophication mediated shifts in the
food chain with its attendant increase in turbidity;
i.e., under eutrophied conditions there would be a
selective advantage for species that are
omnivorous (Bigelow and Schroeder, 1953) and
which do not feed primarily by sight Grecay
(1990) showed that weakflsh juveniles (which are
sight-feeding predators) were more successful at
obtaining prey when light was not severely limited
by turbidity. Vaas and Jordan (1991) also noticed
a steady increase in Fundulus spp. in the
Chesapeake Bay over the last 32 years, which they
attributed to the effects of eutrophication. There
might be some slight indication of an increase in
Fundulus spp. in the Maryland system as well, but
it might be too early to judge if this is truly
representing an impact of eutrophication. It is
important to recall the great difference in
watershed area and resulting nutrient impact on
the two systems. The Delaware inland bays have
a watershed to water ratio of 10 to 1, while the
ratio for the Maryland bays are close to 1 to 1;
which might go a long way in explaining the
differences in species dominance.
Therefore, we are reporting here for the first time
that dominance of shore-zone fish communities by
species from the Family Cyprinodontidae is an
apparent indicator of eutrophication in certain
estuarine systems.
A-52
-------
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A-53
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Weakfish (Cynoscion regalis) in Delaware Bay: Field and Laboratory Assessment Ph.D.
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Grant, G. C. 1962. Predation of the bluefish on young Atlantic menhaden in Indian River, Delaware. Ches.
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A-56
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ATTACHMENT
A-57.
-------
Table 1. List of species collected in Maryland's coastal bays between April and October, 1993. Fish, crustaceans, and other
species are listed separately. Total trawl sites = 140, total seine sites = 38.
Species
A. Fish
Bay Anchovy
(Anchoa mitchilli)
Atlantic silverside
(flfenidia menidia)
Spot
(Leiostomus xanthurus)
Atlantic menhaden
(JBrevoortia tyrannus)
White mullet
(JMugil curenw)
Golden shiner
(Wotemigonus crysoleucas)
Atlantic croaker
(Micropogon undulatus)
Silver perch
yUairdiella chrysoura)
Weakflsh
(Cynoscion regalis)
Summer flounder
(Paralichthys dentatus)
Inshore lizardfish
(Synodus foetens)
Hogchoker
(Trinectes maculatus)
Striped killifish
(Fundulus majalis]
Northern puffer
(jSphoeroldes maculatus)
Total
Trawl
n=140
20,249
27
1,118
23
1
0
894
184
217
222
148
81
0
78
Number
Seine
n=38
4,331
10,947
1,155
894
2132
959
3
1,056
1
30
90
6
380
72
Collected
Total
24,580
10,974
2,273
917
2133
959
897
1,240
218
252
238
87
380
150
Mean
Trawl
144.6
0.2
8.0
0.2
0.01
0.0
6.4
1.3
1.6
1.6
1.1
0.6
0.0
0.6
CPUE
Seine
114.0
288.1
30.4
23.5
56.11
25.2
0.1
27.8
0.03
0.8
2.4
0.2
10.0
1.9
A-58
-------
Species
Striped anchovy
(Anchoa hepsetus)
Atlantic needlefish "
(Strongylura marina)
Black sea bass
(Centropristis striata)
Northern pipefish
(Syngnaihus fuscus)
Bluefish
(jPomafomus saltatrix)
Blackcheek tonguefish
(Symphurus plagiusa)
Oyster toadfish
(Opsanus tow)
Spotted hake
(Urophycis regius)
Northern searobin
(frionotus carolinus)
Butterfish
(feprilus triacahthus)
Rough silverside
(Membras martinica)
Northern kingf ish
{Menticirrhus saxatilis)
Smallmouth flounder
yStropus mtcrostomus)
Spotfin mojarra
(jEucinostomus argenteus)
Gag
Total
Trawl
n=140
15
0
10
141
3
4
7
20
16
.13
0
7
20
0
0
Number Collected
Seine Total
n=38
69
69
1
88
28
6
97
0
2
0
361
17
10
17
1
84
69
11
229
31
10
104
20
18
13
361
24
30
17
1
Mean CPUE
Trawl
0.1
0.0
0.1
1.0
0.02
0.03
0.1
0.1
0.1
0.1
0.0
0.1
0.1
q.o
0.0
Seine
1.8
1.8
'0.03
2.32
0.7
0.2
2.6
0.0
0.1
0.0
9.5
0.5
0.3
0.4
0.03
(fifycteroperca microlepis)
A-59
-------
Species
Rainwater killifish
(Luciana parva)
Fourspine stickleback
(Ap<es quadnacus)
American eel
(Anguilla rostrata)
Spotted seatrout
(Cynoscion nebulosus)
Winter flounder
(Pseudopleuronectes americanus)
Windowpane flounder
(Scophthalmus aquosus)
Blueback herring
(Alosa aestivalis)
Atlantic herring
(Clupea harengus)
Lookdown
(Selene vomer)
Brown bullhead
(Ameiurus nebulosus)
Striped cusk eel
(Ophidian marginatum)
Crevallejack
(Caranx hippos)
Feather blenny
tffypsoblennius hentzi)
Tautog
(Tautoga onitis)
Naked goby
Total Number Collected MeanCPUE
Trawl . Seine Total . Trawl Seine
n=140 n=38
55
74
. 31
6
15
6
1
1,893 •
2
0
• " 16
10
1.1
3
60
378
39
119
10
26
1
0 -
1
0
2
1
29
15
3
109
433
;
113
150
16
41
7
1
1,894 .
2
2
17
39
26
6
169
0.4
0.5
0.2
0.04
0.1
0,04
0.01
13.5
0.01
'
0.0
0.1
0.1
0.1
0.02
0.4
10.0
.1,0
3.1
0.3
0.7
. ; -0.03
0.0
0.03
0.0
0.1
. - 0.1
0.8
0.4
0.1
2:9
(Gobiosoma bosci)
A-60
-------
Species
Lined seahorse
(JHyppocampus erectus)
Red snapper
(Lutjanus campechanus)
Sheepshead minnow
(Cyprinodon variegatus)
Scup
(Stenotomus chrysops)
Striped burrf ish
(Chilomycterus schoepfi)
Banded killifish
(Fundulus diaphanus)
Black Crappie
(Pomoxis nigromaculatus)
Halfbeak
(Hyporhamphus unifasciatus)
Pumpkinseed
(Lepomis gibbosus)
Bluegill
(Lepomis macrochirus)
Gizzard shad
(Dorosoma cepedianum)
Striped searobin
(Prionotus evolans)
Conger eel
(Conger oceanicus)
Spotf in butterflyfish
(Chaetodon ocellatus)
Red drum
(Sciaenops ocellata)
Skilletfish
(Gobiesox strumiosus)
Total
Trawl
n=140.
0
4
1
13
5
0
0
0
0
0
2
9
1
1
2
1
Number Collected
Seine Total
n=38
1
9
34
3
6
131
2
1
53
8
12
8
0
0
0
3
1
13
35
13
11
131
2
1
53
8
14
17
1
1
2
4
Mean
Trawl
0.0
0,03
0.01
0.1
0.04
0.0
0.0
0.0
0.0
0.0
0.01
0.1
0.01
0.01
0.01
0.01
CPUE
Seine
0.03
0.2
0.9
0.1
0.2
3.4
0.1
0.03
1.4
0.2
0.3
0.2
0.0
0.0
0.0
0.1
A-61
-------
Species
Tidewater silverside
(Menidia beryllina)
Mosquitofish
(Gambusia holbrooki)
Common trunkfish
(Lactophrys trigonus)
Crabeater
(Rachycentron canadus)
Bluespotted sunfish
(Enneacanthus gloriosus)
Bluenose ray
(Myliobatis freminvillei)
Pigfish
(Orthopristis chrysoptera)
Alewife
(Alosa pseudoharengus)
White perch
(Morone americana)
Smooth butterfly ray
(Gymnura micrura)
Green goby
(Microgobius thallassinus)
Atlantic spadefish
(Chaetodipterus faber)
Spanish mackerel
(Scomberomoms cavalla)
Rough scad
(Trachurus trachurus)
Dwarf Goarfish
(Upenus parvus)
Total
Trawl
n=140
0
0
0
0
0
0
0
0
0
1
24
2
1
1
Number Collected
Seine Total
n=38
15
2
1
4
2
4
1
15
44
0
10
0
0
1
1
15
2
1
4
2
4
1
15
44
1
34
2
1
2
1
Mean
Trawl
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.01
0.2
0.01
0.01
0.01
0.0
CPUE
Seine
0.4
0.1
0.03
0.1
0.1
0.1
0.03
0.4
1.2
0.0
0.3
0.0
0.0
0.03
0.02
A-62
-------
Species
Blue crab
(Callinectes sapidus)
Sand shrimp
(Crangon septemspinosa)
Grass shrimp
(Palaemonetes sp.)
Brown shrimp
(jPenaeus aztecus)
Lady crab
(Ovalipes ocellatus)
Mud crab
(ffeopanope texana sayi)
Hermit crab
(Pagurus longicarpus)
Mantis shrimp
(Squilla empusa)
Spider crab
(Libinia emarginata)
Mud crab
(Panopeus sp.)
Hermit crab
(Pagurus poUicaris)
Rock crab
(Cancer irroratus)
Mud shrimp
(Callianassa atlantica)
Total
Trawl
n=140
7,640
9,801
3,136
104
106
35
55
36
36
10
6
58
7
Number Collected
Seine Total
n=38
5,064
123
17,776
22
146
1
30
0
0
0
1
0
1
12,704
9,924
20,912
126
252
36
85
36
36
10
7
58
8
Mean
Trawl
54.6
70.0
22.4
0.7
0.8
0.2
0.4
0.3
0,3
0.1
0.04
0.4
0.05
CPUE
Seine
133.3
3.2
467.8
0.6
3.8
0.03
0.8
0.0
0.0
0.0
0.03
0.0
0.03
A-63
-------
Species
Long-finned squid
(Loligo pealei)
Forbes asterias star
(Asterias forbesi)
Oyster drill
(Urosalpinx cinereus)
Horseshoe crab
(Limulus polyphemus)
Diamondback terrapin
(flfalaclemys centrata concentrica)
Mud snail
Wassarius vibex)
snail
(tfassariidae)
Hard shell clam
(Mercenaria mercenaria)
Lobed moon snail
(JPolinices duplicatus)
Mulinia lateralis
Haminoea solitaria
Tellina agilis
Ensis sp.
Solen sp.
Eupleura caudata
CATEGORY
A. Fish
B. Crustaceans
C. Other
Total Number Collected
Trawl
n=140
39
21
2
16
55
43
8
98
1
8
5,310
4
3
5
7
Seine Total
n=38
0
0
0
1
_ • • j
12
1
1,014
2
0
0
0
0
0
2
1
39
21
2
17
67
44
1,022
100
1
8
5,310
4
3
7
8
TOTAL NUMBERS
50,444
44,194
6.653
101,291
Mean CPUE
Trawl
0.3
0.2
0.01
0.1
0.4
0.3
0.1
0.7
0.01
0.1
37.9
0.03
0.02
0.04
0.1
Seine
0.0
0.0
0.0
0.03
0.3
0.03
26.7
0.1
0.0
0.0
0.0
0.0
0.0
0.1
0.03
TOTAL SPECIES
79
13
15
107
A-64
-------
APPENDIX B
Area-weighted Mean Concentrations
for all Measured Sediment Contaminant
B-1
-------
Appendix Table B-1 . Mean concentrations (90% confidence intervals) of sediment contaminants in
the Delaware/Maryland Coastal Bays and Artificial Lagoons
,
Metals (ppm)
Aluminum
Antimony
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Tin
Zinc
SEM-Cadmium
SEM-Copper
SEM-Nickel
SEM-Lead
SEM-Zinc
Pesticides (ppb)
DDT and its metabolites
Total DDD
Total DDE
Total DDT parent
Total DDT
o,p'-DDD
p.p'-DDD
o,p'-DDE
p,p'-DDE
o.p'-DDT
p.p'-DDT
Total OPDDT
Total PPDDT
Coastal Bays
44,1 03 ±7,421
0.23 ± 0.09
7.03 ±1.91
0.14 ± 0.05
41 .98 ±10.58
9.52 ± 2.81
20,588 ±4,61 9
24.14 + 5.83
283 ± 40
0.04 ± 0.01
13.93 ±4.65
0.33 + 0.17
0.05 + 0.02
1.82 + 0.41
64.53 ±16.35
' 0.18±0.13
1.39 + 1.12
. 1.71+1.03
7.69 + 4.66
26.50 ±13.58
0.64 ± 0.42
1.31 ±0.72
0.20 ±0.1 5
2.15 ±1.09
0.09 ±0.09
0.55 ± 0.35
0.19 ±0.14
1.1 2 ±0.60
0.02 ±0.02
0.18 ±0.15
0.31 + 0.20
1.85 + 0.93
Artificial Lagoons
49,605 ± 15,371
0.29 + 0.07
10.64 + 2.09
0.20 + 0.05
56.11 ±20.71
40.64 ±10.38
24, 146 ±7,826
34.35 + 6.60
217 + 54.68
0
21.11 ±9.26
0.42 + 0.10
0.12 ±0.03
2.44+1.30
107.9 ±28.94
0.1 3 ±0.31
3.27 + 2.29
3.16±1.15
7.79 + 1.45
27.68 ± 5.41
1.71+2.17
1.06 ±0.28
0.37 ± 0.92
3.1 4 ±2.91
0.82 ± 0.99
0.89 ±1.20
1.06 + 0.28
0
0.18 ±0.44
0.19 ±0.49
2.06 ±1.27
1.08 + 1.68
B-2
-------
Appendix Table B-1 . Continued
Chlorinated Pesticides
other than DDT
Aldrin
Alpha-Chlordane
Dieldrin
Endosulfan I
Endosulfan II :
Endosulfan Sulfate
Endrin .
Endrin Aldehyde
Endrin Ketone
Heptachlor
Heptachlor Epoxide
Hexachlorobenzene
Lindane
Mirex :
Total Chlordane
Trans-Nonachlor
PCB Cogeners (ppb)
No. 8
No. 18
No. 28
No. 44
No. 52
No. 66
NO. 101
No. 105
No. 118
No. 128
No. 138
No. 153
No. 170
No. 180
No. 187
No. 195
No. 206
No. 209
Total PCBs
Coastal Bays
0.15 ±0.17
0.15 ±0.18
0.1 3 ±0.07
0.40 ± 0.37
0.17 + 0.14
0.54 ± 0.09
0.04 ± 0.02
0.01 ± 0.02
0.14 ±0.17
0.13 ±0.12
0.04 ± 0.05
0.05 ± 0.04
0.20 ±0.1 5
0.12 + 0.17
0.41 ± 0.39
0.12 ±0.11
0.21 ±0.18
0.23 + 0.18
0.37 ± 0.20
0.07 ± 0.05
0.13 ±0.09
0.23 + 0.13
0.23 ±0.1 4
0.10 ±0.05
. 0.24 ±0.1 2
0.01 ± 0.01
0.21 ±0.13
0.32 ±0.13
0.12 ±0.12
0.07 + 0.06
0.13 + 0.07
0.07 + 0.07
0.05 ±0.04
0.10 ±0.07
2.89 ±1.04
Artificial Lagoons
0.03 ± 0.08
1.21 ±0.39
1.66 + 1.83
0.57 ±0.1 3
0.06 + 0.16
5.17 + 1.12
0.65 ±0.16
0.01 + 0.03
0.55 + 0.16
0.03 ± 0.07
0
0.63 ±0.41
0.94 ± 0.20
0.01 ± 0.03
1.85 ±0.74
0.61 ± 0.33
0.03 ±0.10
0.54 ± 0.38
7.32 ±5.1 5
2.06 ± 2.96
4.23 + 1.48
0.28 + 0.69
0.1 8 ±0.46
1.12 ±0.84
0.1 9 ±0.46
0.27 ± 0.72
0.46 + 0.28
0.68 ± 0.89
0.55 ± 0.25
0.1 4 ±0.36
0.95 + 0.59
0.81+0.99
0.01 +0.16
0
19.81 ± 5.51
B-3
-------
Appendix Table B-1 . Continued
Polycyclic Aromatic Hydrocarbons
(ppb)
Acenapthene
Acenapthylene
Anthracene
BenzoManthracene
Benzcfeipyrene
Benzo[e]pyrene
BenzoBj,k]fiuoranthene
Benzdg,h,i]perylene
Biphenyl
Chrysene
Dibenz[a,h,]anthracene
2,6-Dimethyinaphthalene
Flouranthene
Fluorene
Inden[1,2»3-cd]pyrene
1 -methylnaphthaiene
2-methyInaphthaIene
1 -methylphenanthrene
Naphthalene
Perylene
Phenanthrene
Pyrene
Total 2-Ring PAHs
Total 3-Ring PAHs
Total 4-Ring PAHs
Total 5-Ring PAHs
Total 6-Ring PAHs
1 ,6,7-trimethylnaphthaIene
Total High Moi. Wt PAHs
Total Low Moi. Wt. PAHs
Total PAHs
Other Measurements
Acid Volatile Sulfide (ppm)
Dibutyltin (ppb)
Monobutyltin (ppb)
Tributyltin (ppb)
Total Butyl Tins (ppb)
Total Organic Carbon (ppm)
Coastal Bays
1.38 ±1,06
0.27 ± 0.23
3.87 ± 2.34
8.82 ± 4.38
6.60 ± 4.23
8.27 ± 4.26
25.31 ± 12.30
10.14 ±5.17
2.11 ±1.51
11. 12, ±5.06
0.65 + 6.69
^6.33 ±3.10. ,
•31.0Q± 12.69 ;'•' ."
4.20 ±2.61' ' ' '
9.73 ± 5.77
4.23 ± 2.46
11.51 ±5.27
0.57 ± 0.74
13.49 ±5.66
26.01 ± 13.87
24.80 ±11. 82
20.48 ± 8.50
40.74 ±17.1 3
33.45 ± 15.52
60.30 ± 24.98
87.70 ± 43.90
10.14 ±5.17
1.42 ±0.94
158 ± 71
74 ±30
232 ± 92
231 ± 137
5.56 ±5.15
4.38 ± 4.09
15.48 ± 14.23
25.42 ± 18.25
14,415 ± 3,844
Artificial Lagoons
2.1 3 ±5.35
0.72 ± 2.07
59.92 ± 63.81
210 ±292
79.46 ±31 .60
94.32 ± 752.49
268.8 ± 90.39
60.00 ±21 .15
0.1 9 ±0.54
385.04±213.14
17.96 ±10.1 8
16.11 ±3.09
31 5.50 ±265.59
19.28 ±13.77
74.1 9 ±26.86
2,02 ± 5.18
19.05 + 4.19
6.72 ±18.87
18.36 ±5.46
73.83 ± 33.82
85.57 ± 33.84
250.87 ± 157.48
59.65 ±17.47
171.50 + 129.03
776.20 ±71 3.85
993.59 ± 352.82
59.97 ±21. 16
1.07 ±2.80
1,829± 964
231 ± 143
2,061 + 1,103
1,271 ±753
0
0
0
0
21 ,083 ±3,726
B-4
-------
APPENDIX C
Area-weighted Mean Abundances of
Benthic Macroinvertebrate Species
C-1
-------
o
rb
Group
Anthozoa
Turbellaria
Nemertinea
Slpuncula
ffivalvia
Name
Anlhozoa
Cerianlheopsis americanus
Turbellaria
Nemertinea
Sipuncula
Aligena elevata
Anadara transversa
Anomlidae
Bamea Iruncata
BivaMa: Other - Suspension
Feeders
Chione spp.
Ensis directus
Gemma gemma
Lyonsia spp.
Macoma balthica
Macoma tenta
Mercenaria mercenaria
Mulinia lateralis
Mya arenarla
Mysella planulata
MytiSdae
Mytilus eduBs
Nucula annulata
Entire
Study
Area
144.36
2.61
11.32
123.11
0.70
1.08
9.68
10.47
2.09
33.10
0.57
7.78
1184.23
1.40
0.70
38.23
54.04
445.93
0.70
1.40
0.54
2.98
12.19
Rehoboth
Bay
277.72
3.78
79.35
0.94
2.83
35.90
12.28
3703.86
4.72
72.74
43.45
17.00
3.78
Indian
River
124.48
1.35
26.07
32.98
42.02
2.71
13.53
878.18
26.36
30.13
0.65
0.33
12.83
Assa-
woman
Bay
10.85
13.68
135.63
0.61
0.61
7.77
3.28
237.38
7.47
1.51
478.99
0.30
12.22
Chlnco-
teague
Bay
281.52
6.78
6.78
257.77
3.39
3.39
44.09
50.88
10.18
71.23
1404.19
6.78
3.39
169.59
71.23
1414.37
3.39
6.78
30.53
Upper
Indian
River
180.22
26.57
20.78
52.18
1299.71
0.97
12.56
0.97
0.48
0.97
SL
Martin
River
11.44
0.42
28.82
0.85
0.85
3.39
0.85
197.48
2.97
2.12
284.78
0.42
2.12
Trappe
Creek/
Newport
Bay
47.85
1.45
2.17
34.80
0.72
.2.90
5.07
7.25
133.40
0.72
Artificial
Lagoons
1.27
1.11
0.11
12.78
0.03
0.16
0,03
-------
o
CO
Group
Gastropoda
Name
Periploma margaritaceum
Petricola pholadiformis
P'rtar morrtiuanus
Sotemya velum
Spisula solidissima
Tagelus divisus
Tagelus spp.
Tellina apilis
Tellinidae
Veneridae
Yokfialimatula
Acteocina canaliculata
Astyris lunata
Brttium altematum
Boonea seminuda
Cratera pilata
Crepidula spp.
Doridella obscura
Eupleura caudata
Gastropoda: Other
Haminoea solitaria
llyanassa obsdeta
Nassarius spp.
Nassarius trivittatus
Entire
Study
Area
11.16
0.16
11.16
25.33
2.93
2092.92
3.45
450.51
31.79
0.57
131.31
2.79
212.11
4.88
2.33
8.19
0.16
1.07
85.24
31.71
0.70
0.69
0.07
Rehoboth
Bay
0.94
1.89
10.39
51.01
14.17
300.39
37.78
4.72
3.78
10.39
0.94
0.94
6.61
30.23
Indian
River
5.41
76.07
4.24
1359.49
50.00
2.71
10.36
0.98
6.06
14.93
13.81
3.26
0.33
Assa-
woman
Bay
5.35
11.10
0.61
74.19
45.27
19.64
3.03
1.21
28.57
8.33
Chinco-
teague
Bay
54.27
54.27
98.36
9381.62
47.48
13.67
549.47
13.57
1031.10
23.74
3.39
23.74
3.39
362.92
16.96
3.39
Upper
Indian
River
112.58
6.28
73.92
71.99
5.31
1.45
0.97
12.08
16.43
4.83
0.48
St
Martin
River
8.05
0.85
36.45
29.66
1.27
4.24
1.70
2.54
0.42
Trappe
Creek/
Newport
Bay
0.72
154.42
23.20
15.22
39.15
1.45
2.90
Artificial
Lagoons
1.03
0.29
0.03
0.09
0.02
0.02
0.39
0.02
-------
o
Group
Oligochaeta
Potvctiaeta
Name
Nassarius vibex
Odostornia engonia
Odostomia spp.
Pyramided crenulata
Pyramidella spp.
Pyramktelfidae
Rictaxis punctostriatus
Turbonilla interrupta
Aulodrius p'flueti
Umnodrilus claparedianus
LJmnodrilus hoffmeisteri
OHoochaeta: Heads
Tubificidae with capJiform
ctiaetae
Tubffiddae without capiliform
ctiaetae
Amastigos caperatus
Ampharetidae
Amphitrtle omata
Apoprionospto pygmaea
Arabella iricolor-muttidentata
complex
Arlcidea catherinae
Ariddea fragilis
Asabellides oculata
Entire
Study
Area
4.16
8.08
5.05
0.70
2.88
0.72
82.06
157.23
0.21
0.21
1.45
932.09
4.35
0.21
6.69
23.22
2.79
0.16
3.88
11.86
0.10
0.49
Rehobolh
Bay
1.89
1.89
47.23
51.95
1345.14
34.01
1.89
0.94
2.83
Indian
River
2.29
4.29
8.16
151.76
4.71
1166.75
4.06
Assa-
woman
Bay
0.91
0.30
146.74
83.12
86.61
0.30
0.91
Chlnco-
teague
Bay
13.57
23.74
6.78
3.39
33.92
579.99
1370.27
108.54
13.57
16.96
57.66
Upper
Indian
River
3.38
4.35
12.08
198.58
0.97
267.19
St
Martin
River
1.27
0.42
14.41
37.72
31.36
0.42
1.27
Trappe
Creek/
Newport
Bay
1.45
13.77
13.05
5.07
6.52
79.75
1.45
1.45
10.15
56.55
30.45
1.45
1.45
0.72
Artificial
Lagoons
1.73
' 0.12
22.82
0.29
-------
Group
Name
Boccardiella hamata
Brania davata
Brania spp.
Brania wefflteetensis
Cabira incerta
Capitela spp.
Capteidae
Capitellktes jonesi
Carazziella hobsonae
Ceratonereis irritabis
Cirriformia grandis
Ctymenella torquata
Cossura longocirrata
Demonax microphthalmus
Diopatra cuprea
Docviltea rudolphi
Dowilea social Is
Drilonereis longa
Eumida sanguinea
Eunicidae
Exoqone dispar
Glycera americana
Glycera dibranchiata
Glvcera SPD.
Entire
Study
Area
12.56
20.90
2.16
7.57
4.39
286.74
0.34
0.64
453.14
69.88
0.70
92.33
27.19
17.12
140.67
12.32
7.68
1.27
29.46
26.51
556.40
63.58
3.13
15.70
Rehoboth
Bay
18.89
14.17
1193.06
0.94
6.61
0.94
24.56
0.94
5.67
51.01
15.11
9.45
Indian
River
9.51
315.54
0.33
3.03
1.35
2.01
4.24
1.68
1.35
0.33
1.68
10.12
6.76
Assa-
woman
Bay
34.02
10.75
0.30
35.74
115.98
131.44
22.46
38.16
9.29
12.41
29.48
5.35
Chinco-
teague
Bay
61.05
33.92
20.35
61.05
2048.63
339.18
3.39
234.03
3.39
50.88
593.56
57.66
37.31
3.39
125.50
128.89
2367.45
193.33
13.57
54.27
Upper
Indian
River
12.08
0.48
0.48
0.48
0.97
6.28
0.48
0.48
0.48
0.97
SL
Martin
River
10.17
3.81
0.42
5.09
50.01
26.70
12.71
8.48
5.51
17.38
3.81
Trappe
Creek/
Newport
Bay
13.05
0.72
1.45
4.35
1.45
47.85
0.72
39.15
1.45
6.52
28.27
2.17
213.14
21.75
2.90
Artificial
Lagoons
9.97
1.44
0.12
0.29
0.25
-------
Group
Name
Glyclnde soDtan'a
GoniadWae
Harmothoe extenuata
Heteromastusfiformis
Hobsonia florida
Hvdroides dianthus
Hydroides spp.
Hypereteone fofiosa
Hypereteone heteropoda
Laeonereis cutveri
Leftoscdoplos robustus
Leitosooloplos spp.
Lepidonotus sqjamatus
Loimia medusa
Lumbrineridae
Macroclymene zonalis
Magelona spp.
Maldanidae
Marphysa sanguinea
Mediomastus ambtseta
Mediomastus califomiensis
Mediomastus spp.
Melinna maculata
Melinna spp.
Entire
Study
Area
410.41
3.99
1.34
168.50
280.87
0.54
1.63
15.61
19.28
31.99
65.11
2.79
0.21
102.37
92.70
0.29
148.72
4.42
3230.09
49.84
4923.19
179.39
10.47
Rehoboth
Bay
113.35
12.28
4.72
236.16
1.89
34.95
76.51
15.11
56.68
238.04
1.89
7.56
1138.27
1335.69
4.72
Indian
River
136.38
0.65
169.70
0.65
26.54
2.71
89.56
164.94
29.81
8.12
1.35
7.74
823.67
0.65
756.60
2.99
Assa-
woman
Bay
254.30
0.91
2.68
58.10
0.30
2.68
0.91
8.12
1.21
13.73
6.91
28.92
47.05
78.53
0.30
436.08
0.30
519.52
235.32
Chlnco-
teague
Bay
1305.83
6.78
339.18
1363.49
3.39
3.39
20.35
30.53
88.19
13.57
203.51
271.34
539.29
20.35
10880.78
240.82
18264.65
501.98
50.88
Upper
Indian
River
121.76
0.97
72.96
0.97
21.26
30.44
45.90
12.08
1.45
398.13
0.97
583.18
2.42
St
Martin
River
56.36
1.27
10.17
0.42
1.27
7.63
1.70
4.24
5.93
6.78
5.93
50.01
0.42
44.92
0.42
60.60
37.29
Trappe
Creek/
Newport
Bay
143.55
2.90
0.72
4.35
5.80
1.45
0.72
1.45
2.90
36.97
44.22
657.56
0.72
2406.21
104.40
Artificial
Lagoons
2.53
0.01
6.60
0.04
0.11
2.68
8.88
1.82
1.44
8.80
3.46
3.95
1.74
0.86
-------
Group
Name
Microphthalmus sczelkowli
Neanthes arenaceodentata
Neanthes succinea
Nephtyidae
Nephtys incisa
Nephtys picta
Nephtys spp.
NereidMae
Notomastus sp. A Ewing
Notomastus spp.
Odontosyllis fulgurans
OnuphkJae
Orbiniidae
Owenia (usiformis
Parahesione luteola
Paranaitis spsciosa
Paraonis fulgens
Parapionosyllis lortgicirrata
Paraprionospio pinnata
Pecdnaria gouWii
Pherusa afflnis
Phytlodoce arenas
Pista palmata
Platvnereis dumerilii
Entire
Study
Area
4.16
7.29
54.62
0.29
1.11
1.26
0.17
20.24
248.54
0.06
84.25
17.12
0.70
11.07
15.23
4.29
2.97
26.58
195.84
7.75
0.82
7.95
241.83
3.49
Rehoboth
Bay
1.89
17.00
24.56
5.67
46.29
99.19
1.89
9.45
5.67
77.46
61.40
11.34
1.89
Indian
River
14.83
5.97
51.49
1.35
2.71
1.35
1.96
233.36
1.31
29.43
9.47
33.49
10.82
1.35
9.80
Assa-
woman
Bay
163.54
2.68
1.82
177.87
0.30
1.82
48.16
11.96
129.17
6.26
2.68
2.72
Chinco-
teague
Bay
3.39
10.18
6.78
50.88
508.76
407.01
71.23
3.39
6.78
20.35
57.66
603.73
10.18
20.35
1173.55
16.96
Upper
Indian
River
1.93
4.83
52.18
2.90
153.16
1.93
41.55
27.54
0.48
SL
Martin
River
49.16
2.54
54.24
0.42
2.54
5.51
12.29
1.27
3.81
Trappe
Creek/
Newport
Bay
13.05
112.37
3.62
0.72
0.72
172.55
0.72
2.90
Artificial
Lagoons
2.00
0.25
0.58
-------
Group
Name
Podarke obscura
Podarkeopsis teviluscina
Polychaeta: Other
Polydrrus spp.
Polydora cbmuta
Polydorasocialls
Polydora spp.
Polynoidae
Prionospio heterobranchia .
Prionospfo perklnsi •
Pygospio etegans
Sabaco elongatus
Sabellariavulflaris
Sabellidae
Scotetepis bousfiekS
Scotelepis spp.
Scotetepislexana
Sooletoma tenuis
Scotoplos rubra
Scoloplos spp.
Serpulidae
Sigambra tentaculata
Sphaerosyllls taylori
Scio setosa
Entire
Study
Area
192.70
58.12
0.07
11.85
125.05
2.63
7.55
0.70
--•121.54.
2.95
17.99
115.71
7.14
118.77
8.68
1.56
41.90
58.51
1.56
0.70
5.58
1.07
15.53
0.32
Rehoboth
Bay
58.57
0.00
5.67
179.48
1.89
0.94
98.24
12.28
0.94
0.94
68.96
64.23
0.94
2.83
1.89
Indian
River
25.33
0.33
83.44'
2.01
8.12
5.41
15.11
- 1.31
16.33
Assa-
woman
Bay
0.61
47.79
0.00
1.21
85.91
2.68
32.11
2.68
5.35
122.80
5.65
10.70
52.40
5.35
23.57
Chlnco-
teague
Bay
936.13
125.50
0.00
50.88
267.95
10.18
3.39
556.25
332.39
33.92
559.64
40.70
6.78
122.10
98.36
6.78
3.39
27.13
40.70
Upper
Indian
River
29.47
0.48
101.46
0.97
4.35
1.93
10.15
SL
Martin
River
0.85
40.68
0.00
1.70
22.88
48.31
0.42
5.93
6.78
Trappe
Creek/
Newport
Bay
18.85
0.00
13.77
1.45
0.72
97.15
10.15
2.17
6.52
• 10.15
Artificial
Lagoons
0.29
0.00
0.53
0.04
0.12
1.38
5.03
0.04
0.02
-------
o
CD
Group
Amphipoda
Name
Spiochaetopterus costaaim
Spiophanes bombyx
Spirofbidae
Soirorfais spp.
Sthenelais boa
Streblospio benedicti
Streptosyflis pettiboneae
SylHdae
Syl tides spp.
Terebellidae
Tharyx sp. A Morris
Ampefisca abdita
Ampelisca abdHa-vadorum
complex
Ampelisca vadorum
AmpeSsca verrilli
Ampilhoe longimanna
Ampithoe spp.
Ampithoidae
Balea catharinensis
Caprella penantis
Caprella spp.
Caprellidae
Ceraous lubularis
Entire
Study
Area
91.80
7.08
1.40
6.28
3.49
1811.87
6.14
4.35
0.29
12.87
102.09
8774.03
9010.89
49.49
695.93
3.56
2.73
20.71
78.32
27.51
2.16
0.86
15.14
Rehoboth
Bay
47.23
18.89
3283.50
25.50
1.89
312.67
3587.67
2563.70
11.34
444.92
20.78
30.23
144.53
103.91
0.94
Indian
River
3.03
5.41
2178.77
1.35
1.35
102.12
14763.49
12843.25
8.44
2.71
66.29
5.74
6.67
Assa-
woman
Bay
51.18
2.68
929.59
8.33
2.68
2.68
8053.75
6294.69
6.56
164.46
0.30
0.61
14.89
6.56
0.30
Chihco-
teague
Bay
298.48
6.78
30.53
16.96
1027.70
16.96
57.66
50.88
7794.28
9011.92
183.16
2570.96
10.18
6.78
223.86
33.92
3.39
37.31
Upper
Indian
River
0.48
485.58
0.97
12019.18
14198.73
0.48
0.48
3.87
St
Martin
River
26.70
1207.78
0.42
5038.77
6168.14
1.70
5.51
0.42
0.85
2.12
1.70
0.42
Trappe
Creek/
Newport
Bay
30.45
819.23
0.72
2.17
3740.91
3812.68
19.57
40.60
13.05
1.45
Artificial
Lagoons
217.37
0.11
1.92
1.67
0.51
0.03
-------
Group
Name
Corophium acherustcum
Corophium acutum
Corophium simile
Corophium spp.
Corophium tuberculatum
Cymadusa compta
Dufchiella appentSculala
Basmopus laevis
Eobrolgus spinosus
Erlcthonius brasiliefisis
Gammaridae
Lembos smith!
Leptocheirus plumulosus
Listriella bamardi
LJstriella ctymenellae
Lysianopsis alba
MelitanHida
Microdeutopus gryllotalpa
Microdeutopus spp.
Microprotopus raneyi
Monoculodes sp. 1 Walling
Mucrogammarus mucronatus
Paracaprella tenuis
Parametopella cvpris
Entire
Study
Area
352.13
0.16
0.10
281.26
166.59
60.10
192.02
662.92
47.49
34.19
0.16
30.70
1.73
285.04
0.72
99.81
2.63
224.51
1.60
180.60
59.70
26.20
125.16
0.46
Rehoboth
Bay
17.00
0.94
14.17
98.24
39.67
102.96
473.26
0.94
105.80
0.94
43.45
78.40
187.04
3.78
221.99
9.45
17.00
19.84
1.89
Indian
River
1519.18
1208.64
169.99
13.39
24.81
246.18
1.35
10.82
8.16
144.69
8.12
9.14
525.41
0.33
135.74
0.65
23.51
3.31
0.65
Assa-
woman
Bay
0.30
0.61
37.05
2.72
147.93
5.35
374.56
3.58
49.34
74.74
0.91
5.65
113.88
68.64
11.15
Chlnco-
teague
Bay
128.89
78.01
295.08
196.72
786.89
2275.87
213.68
57.66
149.24
576.60
359.53
3.39
318.83
3.39
498.59
156.02
6.78
444.32
Upper
Indian
River
586.56
32.86
5.31
5.80
36.72
196.16
12.08
114.03
13.53
285.07
0.48
36.72
0.97
34.79
2.90
0.97
st
Martin
River
0.42
0.85
14.41
3.81
61.02
138.58
1.27
69.08
55.94
1.27
0.42
2.12
21.19
11.87
Trappe
Creek/
Newport
Bay
0.72
24.65
239.24
0.72
50.75
70.32
1.45
5.80
112.37
0.72
0.72
12.32
0.72
2.17
82.65
Artificial
Lagoons
0.03
0.02
0.03
0.01
-------
o
Group
Chiro-
nomidae
Cjrripedla
Cumacea
Decapoda
Name
Pseudohaustorius spp.
Rhepoxynius hudsoni
Stenothoe spp.
Synchelidium americanum
Unciola dissimilis
Unciola serrate
Unciola spp.
Chironomus spp.
Paradadopelma spp.
Tanypus spp.
Tanytarsus spp.
Balanus ebumeus
Balanus spp.
Cyclaspis varans
Leucon americanus
Oxyurostylis smith!
Callinectes sapidus
Crangon septemspinosa
Dyspanopeus sayi
Hippolytidae
Libinia spp.
Ogyrides alphaerostris
Ovalipesocellatus
Entire
Study
Area
0.49
35.58
2.42
56.54
2.36
4.00
12.08
1.55
0.10
1.35
0.10
27.79
174.51
56.87
6.85
2.43
0.16
0.70
0.57
10.21
0.29
Rehoboth
Bay
2.83
2.83
3.78
45.34
25.50
4.72
3.78
0.94
0.94
Indian
River
1.35
2.71
4.06
37.22
176.59
8.72
6.67
1.63
2.71
5.36
1.35
Assa-
woman
Bay
5.35
13.38
1.82
0.91
196.21
45.23
3.89
11.31
Chinco-
teague
Bay
172.98
3.39
271.34
44.09
81.40
257.77
189.94
13.57
3.39
30.53
Upper
Indian
River
55.08
123.21
2.90
3.87
2.42
1.93
St
Martin
River
2.54
1.27
139.85
3.39
1.70
0.85
Trappe
Creek/
Newport
Bay
5.07
2.17
4.35
10.87
0.72
9.42
0.72
2.17
79.02
2.90
1.45
Artificial
Lagoons
0.02
0.02
0.64
0.03
0.03
-------
9
ro
Group
Diptera
Isopoda
Mero-
stomata
Mysidacea
Pycnogonida
Tanaidacea
Name
Pagurus spp.
Pinnixa spp.
Upogebia affinis
Ceratopogonidae
Cvathura burbancki
CyathurapoUta
Cvathura spp.
Edotea triloba
ErichsoneDa attenuata
Erichsonella filiformis
Erichsonella spp.
Idolea baHhica
Isoooda: Other
Paracerceis caudata
Umulus poryphemus
Heteromysis formosa
Mysklae
Mysidopsis almyra
Mysidopsis bigelowi
Anoplodactylus petiolatus
Callipallene brevirostris
Tanystylum orbiculare
Haraeria raoax
Entire
Study
Area
0.29
2.51
0.70
0.10
75.62
5.37
140.93
4.19
2.33
2.49
0.29
0.70
18.14
0.12
3.93
0.60
0.29
56.58
5.78
21.96
0.16
110.40
Rehoboth
Bay
34.95
8.50
56.68
13.22
0.94
17.95
51.95
7.56
0.94
Indian
River
1.35
5.27
9.14
170.23
1.35
4.06
0.33
1.35
12.64
9.47
Assa-
woman
Bay
5.35
5.35
176.05
0.30
4.54
0.61
2.68
8.93
12.52
13.78
1.21
Chlnco-
teague
Bay
3.39
250.99
3.39
186.55
20.35
3.39
3.39
88.19
200.11
10.18
54.27
532.51
Upper
Indian
River
5.80
13.53
231.92
0.48
8.70
14.01
St
Martin
River
167.82
0.42
6.36
0.85
1.27
2.54
8.05
1.70
Trappe
Creek/
Newport
Bay
0.72
17.40
1.45
35.52
3.62
13.05
0.72
Artificial
Lagoons
0.04
0.46
0.01
0.40
0.12
0.25
-------
Group
Phoronida
Biyozoa
AsterokJea
Hoto-
thuroidea
Hemt-
ctordata
Asddiacea
Name
Leptochelia dubia
Phoronis spp.
Amathia convoluta
Anguinella palmata
Asterias forbesi
Asterias spp.
Asteroidea
Havekxkia scabra
Hotothuroidea
Leptosynapta tenuis
Pentamera pulcherrima
Saccogtossus kowatevskS
Motaula manhattensis
Perophora viridte
Entire
Study
Area
0.70
272.92
0.00
0.00
0.32
1.07
5.31
1.54
2.91
31.50
16.85
2.43
0.65
0.00
Rehoboth
Bay
0.94
1.89
17.95
2.83
9.45
3.78
Indian
River
1.35
2.71
Assa-
woman
Bay
6.86
0.00
0.00
5.35
8.33
0.61
0.61
17.06
1.51
Chinco-
teague
Bay
3.39
1207.47
0.00
0.00
3.39
13.57
115.32
81.40
0.00
Upper
Indian
River
St
Martin
River
2.12
0.00
0.00
0.42
0.85
0.85
8.90
2.12
Trappe
Creek/
Newport
Bay
117.45
0.00
5.80
0.72
Artificial
Lagoons
9
CO
-------
-------
APPENDIX D
Minimum, Maximum, Median and Quartile Values
for All Measured Attributes
D-1
-------
Dalautra/tfacylaad Coastal 1*7 » - Mif»le»i characteristic*
xiKUK, 75th r*rcaatll«, n*di*», 25th Mrcratil*, «o4 Kialawa
Mtll**
MXIHM
fCT 7Sn
MCOIJUi
»CT ISMt
HMUIUN
0«**tll*s
Mxunm
tear 19m
•nTM
re* ISTH
NXtjfltm
(WMkil**
•kximm
tC* 7JT»
KM »*•
tMutll*!
MUIIIIM
tCI 7Sf»
MUHM
»Cf 2*n
•I11HUH
Topulatlon
IS.**
11,10
27]**
1.1*
lotir.
11.4*0
27.14*
14.*20
latir»
.«S7*
.12**
.124*
.*»S
.10*4
Intir*
7,*2S*0
7. 7 J 588
T.*****
4S
2*. 7
!«.*
IS. 4
24.1
1.4
ladlan
17.40
2*.7S
27.14
2C.IS
J4.ll
•i**r
.C57<
.*21*
!ll«2
.7(10
1.100
7.14S
7.710
7.J7*
7.1}*
St. iurtitt
«iv«r
11. f
10.*
2*. 4
2f .1
21.7
St. Hcrtia
*l»«r
11.70
21.4*
27.20
2C.12
24.*<
St. Mmrtim
Tcippt Craak
••opart *«y
10.*
2*.*
27. C
2*. 9
2.1
»• "t*my*c*t»e* |
Trapp* Cratk
••Mp«ct lay
2*. 14
27. 1( •
2t.*i
24.12
21.4*
•ttoai dapth (•!
Tc«pp< Cf**k
l«vport lay
1,12*1 2.1114
1.S24* i.uii
1.21*2 l.*240
1.1*4* 1.524*
«.«*** 0.7*20
— »«ti«bla-lotto» p* {pNI -
St. n«rtia Trapp* Crack
ti«*c •••yact lay
1.24
7.1*
7.77
7.71
7.S*
1.4»7S
7. HOI
7.77«
Artificial
12. S
10.7
2*.l
2*.0
21.*
Artificial .
2*.*2
3*.*)*
27.0*
24. *2
Artificial
.*2*t
.5140
-»144
.7(20
ftrtlticial
*.*7
7.K
7,14
1.00
laaaiain^
0*t«««r*
12.**
11.40
10.15
2*. 4*
21.**
"::;;:£
2t.(0*
21.100
2t.01S
24.110
•2£S!
1.132*
l.Ull
1.21*1 •
O.»144
*.*0**
xssa
1.11
1.**
7.41
7.S4
7.1*
•ESS
19.****
ll.t*«l
11.7«2S
1*.10*«
It.fOaO
Marylaad
11.7*00
Jt.HOO
21,1*9*
21.722S
11.10*0
•••Mining
, turylaiii
.41*4
- • .Ull •
.924*
.21*2
*Wr1Uad
1 4201
1.0***
7. 7* IS
^ 7.*1*«
7.2***
-------
a*i»v*t*/n*rri«ia cantn i«yt - rnystoi ca«r*cc«rntici
M»im», 75th r«rc«ntil«, HidUn, 25th Mrc«ntil», and Hinl«u«
V«ti«bl.-silt-Cl«T Cont.ot
Upp.i
Utlr> Indian St. Martin Tr«pp* cr««k ArtiCiclil ••••iatag (•••inln^
apulctioft Blv*t Hv«c Mvpcct »»T Ufoan* D*l>»>c* H*iyl«a4
mxnnm t*.t7ii ft.nai 11.1721 »».««j« to.ia«« »
Kt 1ST! l«.*i«] *J.t411 77,111* . *S.f22f tl.2111 74.131I «l.J57l
WDlM ««.41«* 7f.dll Cl.llll 74. tlJt 7*. 171* 12.1117 J*.«101
tn 2SM 1S.1C27 «».«2J1 1S.1IS4 41.7*11 17.««J7 S.JI70 «.S«7*
iaaf«im i.j*** j,s««i 4.71*2 2. sat* 2.42*4 J.tuo 1.1*01
-------
0*l*tt«K*/H«rfl*Bd Ceiatil My* - W«t«r Quality Vtr«B«t*c«
15th f»ce*«til*. H«di«n, 2Sth T«»c»mtll«, «od Mill*
tati» Indian St. H«ttin Tr*pp« Cc*«k Artificlml •••cluing (Miiaioq
guixtilo ropulitltn Ilr»r »l»«r import g«y Ltgoont o«l»*r* furyitnd
*2.4«0 42.« 17.1* 22.70 JO.lfl 2*.l* 2f.4*
fCT TSI« 5.*29 12.40 4.42 l.*4 4.11 «.41 5.77
ntDIIJI J.ISS 9.19 2.It 2.11 2.43 3.10 l.»l
•Of 1911 ».»50 3.29 1.01 O.tl 0.73 1.1* 0.77
HiBimm *.*oo o.io 4.23 o.oo a.is o.»o o.»o
• T»rl«bl*-i«ntblc cH_« B li»«r Riv*c IWvpact *»f t«f»«at
•AZIKUM 115.7* 34.1 52.tt 19.70 CO.OO 119.70 11.2
tCT 79n 17.lt 14.3 10.>0 4.*9 49.99 24.7* «.»
moijUl 7.45 0.5 4.»5 l.*5 14.49 12.09 1.0
tCt »«• 1.49 4.S 1.5* 1.49 19.99 *.** 1.7
•nUMN 0.90 1.1 1.00 1.10 (.2* l.*0 0.9
to« Dloalvtd OSfflCB (pp*l —
Iidi«o »t. HirtlB TK*W« Cr««k Mtiticitl
•i*«t ll««c •••port »tj Ufaaa*
17.tOO !.«•
tCT lit* «.«45 1.2*
HIOTA* C.O*S «.01
tcr 25tB 5.40* 4.9t
HMIlim 0.2*0 l.OC
.13 17.11 4.fl 10.900 0.1*
.1* 4,*7 4.1* C.«0« «.««
.41 4.11 5.00 4.115 t.iO
.1* 9.71 1.10 9.594 9,77
.00 4.11 *.20 1.00* |.t*
-------
Haiiaua. 75th rareaatil*. Median, 25th ••rcaatll*. «od Hioiaia
lorophyll a («a/l)
g«aatil«a
HAZIHVH
•CT 75T»
MO?AI
wet 2 STB
Batira
PopulatiaB
171.25
14il*
7.1*
Upp*r
ladlaa
•ivar
15.55
41.54
11.»«
10. *•
St. Hicttn
12.10
21.27
II.40
15.47
11.17
Trappa Craak
B*op«rt lay
171.25
22.21
11.55
*.*•
2.41
Artificial
tafooa*
11*.01
11. «2
21.11
IS.14
2.22
IXlavaca
It.22
11.50
7.15
l.fi
•••aiaiao.
•aryland
21.<••
sisiS
1.000
0.11*
—— »ariabla-MO2+IO) (aHoll
lutic*
KAIIlfBH
rCT 7ST«
»CT 2ST«
0.415
• .170
• ••(9
• .ooo
»pp«r
ladiaa
liver
IS.M
2.41
o!oi
St. BlttlB
.42
.!«
.t4
.00
Trappa Craak
••opart lay
52.20
• .2*
• .14
• .0*
o.oo
Artificial
11.20
0.2«
0.14
0.«4
• ••0
Dalaoar*
7.§40
• .410
0.225
• .12*
0.000
(Urylaad
.It
.52
.10
.00
TarUbla-OrtBopaaaphata K>4 <«Hal)
Qaaatila*
KAIIHim
»CT 75«
MOTJUI
•CT 2Sra
•IBIIIBII
Entire
12.70
0.55
0.2f
• .19
• .04
ladlaa
.17
.2*
.15
.11
St. Nartia
lirar
.24
.14
.21
.11
fraap* Craak
••oport ••*
12.7*
• .47
0.11
0.1*
artificial
Latooaa
.57
.19
.24
.19
Oclaoat*
0.91
0.04
•••aiaiaf
•arrlaad
O.*40
0.4(0
0.245
0.15*
• ••70
Ovaatil**
•AXIHim
HTt 75T»
BioTu
»CT 25t«
ni«Tmm
latir*
Populatioa
44.07
f.ll
5.40
1.22
-1.20
Iidiaa
44.17
JO.Ji
14.25
«'«5
St. Nartia
21.27
7i7»
1.17
Trapp* Cr««k
•••port lay
12. »1
t.*(
S.40
1.4*
-1.20
Artificial
Lao,«oaa
1«.44
10.70
s!s5
1.14
Dalavar*
17.91
7.14
5.19
••••iaiaf
lUrylaad
«.940
1.070
2.555
l.*70
0.520
-------
Dalavara/Haryl'Bd Ceaital »«r» - Watar Quality faraaatari
Htxiama, T5th rareantila, Haitian, IStB f«rc«ntlU, nod t
gttaatilai
lotir.
rc*_7S*«
MUHM
rc* 25T«
Himratt
.(7
.1*
,51
.11
«?pac
Indian
•ivar
.71
.SI
.SO
.10
St. Martin
«l»at
1.12
«.«2
a. si
0.50
0.14
Tr»»p« Ct**k
1.07
0.7*
t.ta
0.41
0.21
Artificial
La^ooni
0.75
O.f7
0.54
0.40
Dalaxar*
0.11
0.5«
0,11
Maryland
l.tf
1.10
e.if
0*4t
Qaantil*!
M1INON
re* 7ST«
HlofjM
ror" is*«
nmfMim
lotlra
•opalatioa
10J.OO
21 !f*
21. It
(.01
Wapa
ladla
»l»a
If.
IS*.
11.
11.
(tlltoM
. Hartin Trappa Craak Artificial
Uvar lawaart Bay
Baaainiaf Baaalaiaoj
41.f 1*1.0
17,5 ,17.»
10.« 14.C
l«.l 11.1
22.2 28.•
7». 2
J7.7
11.4
2S.2
57.40
11.10
22. S*
1C.10
• 4.0*
11.
27.
21.
t.
•Total -iliaacrivad .pitaasherua
9aa*til*a
HAXIMIH
ft* 7StB
NUIM
Kt 2STM
Hi«imm
(Btir*
11.1(0
1.140
0.903
0.74*
0.470
Oppar
Indian
*l»ar
.*»
.22
.to
.S*
St. Martin
•ir»r
1.21
l.OJ
4.41
4.47
frapp* Ccaak
••Hyatt lay
11.00
1.01
0.12
0.7C
O.S1
Artificial nanainiai
Lafoani Dalavac*
.7S
.14
.17
.75-
.47
.SI
.21
.•*
.74
.92
Maryland
.Si
l»i/n
latir*
1*41 •
Mutimm
ic* 7Sn
MoTui
rer isw
nmlioiM
44S4.4
2*74.4
lS41.f
421.1
4*01
1421.1
24«» I
11*4.7
St. Hartla
•Ivar
IOS«».
S*ll.
4101.
1JS7.
29S«.
Tiappa Craak
•avport lay
J«47*.7
21(1.«
1147.2
72(.l
artificial
Lafooaa
7*40.2
SOU.4
4114.0
2*44.1
411.*
•anainin?
Oaltvara
fOOl.OO
Ifll.tS
net. 10
11*4.40
414.10
Maryland
4112.10
1412.24
*<•. 10"
444.40
-------
••lima. 19th »«rc«atil», Median, 21th ••rontlle, »ai
HUIMM
»CT 7S*«
MStfM
»Cf_lH«
Bi.Taipi
Entire
fafiiUtloa
4SM.M
111.44
444.14
IK. 11
11.11
latlr*
r*t«Utl«a
.Mil
.•Ml
.MM
.•341
.•••1
Itdlta
•!»•»
1817.
III.
lit.
441.
•B&«wxa«a& r*x«
St. Martin
•Ivar
1471.
•If.
Ml.
S44
mcm^e^* •««s«^«
Trappe Creak
Menport lay
4514.00
4U.17
44f.4«
105 . SO
krtldcial
La«o«aa
114 J. 30
•74.lt
M7.M
41C >••
111. 41*. 105. »7 «4.15
Vati-ifela^Totai VBrticttlBt* ViitfvBBeKBC (•f>'ll
_UIM
eelawara
141*. 11
Sit. 41
IJf.ll
117. »4
11.11
Harylaad
7Sf.4«0
4«1.4M
111.1M
llf .100
1< . 1C7
XavlaB •
.4447
.Mil
•i»«r
.1M4 •
.1110
.Oil
.•llf
.••SI
• Hewport lay
.Mil
.0444
.•111
.•If 1
.•!!•
j j , ,, _ ---.,„.. — — j _*.« ^_— _.._ « «— ^ — ..*_.« •_ *i.*~
' • '. . Quaatllel
- ' BfcllKUtf '•
»CT Itm
- . - ~im7jM'
»cr im
- • mnmM -
9UBtil«*
MAXIMUM
fCT 71WI
H(OT*M
ret lira
MlflilM
. • entire .
••f»l«ti»i
114.44
!•••!
' . !•'.•!' ' '
11.1*
2.M
latir.
lopelatloa
41.
If.
11.
i.
l.
lB«i«* »t. Hart la
'.,. Bi**C '
1M.4
11.1
14.1
U.4
7. a
•*••!
iBalu
U**c
U.4
17.4
It.l
tl.l
*.7
• : «i»«r
111.
17.
... . al.
17.
Tr«O|ie) Cc*afc
•effort lay
111.
11.
• • '!•. '
14.
- n - ._ vaElallle*TttfBldltY fntfl
It. Martia .Trappe Creak
»i««f
4J.»
17.1
14.)
11.7
i.J •' '.
••vport ••r
44.5
11.2
11. •
11. •
1.4
Leaooaa
4.144*
4.«M4
•.••!•
• .Mil
•.•141
4 mm/I. 1 -.——*-.
1 *TW * * -•——""»—
' «*••«»» •
•«.
13.
11.
11.
J.
Artificial
&••*•••
10.90
11.13
1Q.I5
7.50
1.7»
Delavere
.1114
.0755
.05f5
.•!•!
• / -0«»7 .
- leaalaini
Belawara
104.74
41. ••
24.41 •
14.14
1.44
m^taiM
Delawara
J1.40
14.74
1«.«5
• •••
l.*t
Harylaad
.•4544
.45510
.•If 45
.•!•!•
.41104 .
..B-iBlB,
•trrlauM ; - -
• »1. •• • •
!••
- jf.
14.
- 4. '
Natrlu*
40. J
13.7
f.l
!.«
1.1
-------
O»lawar*/Naryl(iid Coaital lays — s«U«l>u», 7Sth f*rc*atU«, Median, 2Stk f««atiU,
V«ciabl*»
•ad Itiaiaa*
Variable
tUIIMtM
*Cf 7SM
NIOUW
PCI isn
HI ix mm
Intir*
21.lt
4.12
0.04
0.40
0.0*
lodlia
mi»«r
21.1
O.t
0.4
0.0
St. lUrtia
Artificial *«••!
17.1
11.4
*.«
o'.s
14.10
o.to
a!oo
.03
.40
.00
.0*
.49
Qamtil*!
nuimm
pet isn
•»!*•
»cr isn
MiBunm
Iltici
45.7
10.»
*.«
Bpp»*
ladiaii
Mvu
4S.70
14.10
11.«4
2.11
4.08
at. Httia
«lv«r
(ppb)
Artlflciil
IS;
10,
4
4
4
It.
4.
0.
0.
0.
••••iaiaf
lUrylcnd
11.1
10.S
0.0
0.0
••.a
Quutilo
•juctmm
ret TSTH
KTT IStl
M»?HON
latin
alati
101
Ofpai
»!«•[
.11
.00
.00
.00
. Mrti«
»!»•!
Artificial
Mfaom
1*2
.00
.M
••tie*
par Tsra
MBit!
pcr_isi«
Miltmiil
II.
12.
I.
Yariahl*-],*-
»»»•*
ladia*
•l*«r
12.M
4.IS
(ppbl —
St. Martin
Mvaf
Artifiolal
lafaaai
3$.
24.
II.
11,
17.
11.
4.
4.
4.
14.
11,
«.
•
I
-------
•axiwm, /sen r.rcantll., Ktdiaa, Uth t*rcan«il«, and Ninimti*
gmatilaa
KU1HUH
fet ism
N*D?M
ret am
•uTum
MMtlla*
NAXIMtnt
vet 7»ti
Matfjlllj
tet am
«.i*»i
o r ™"" " '-
•o
ftvaatUaa
•AX rant
tet 75T»
KKDlu
»et 2sw
mxiTmni
««««*«•«
•ftXIMM
»ct 7sn
UOlAJI
»cr 2m
•HIHUH
latira
•«B«lati.B
St.
21.
14.
0.
0.
I>tll*
r«|Hilatiaa
11.20
4. ft
0.00
o.oo
.0.
(•tir*
•apulatioa
11.
0.
0.
0.
0.
toi>«Uti«*
410*.
1110.
III.
•t.
1.
variaDi*
•l»-f
S*.M
11.10
12. 10
11.40
t.Ol
Indian
•i»or
10.1
0.0
0.0
0.0
0.0
M V*ci*b
indiaa
tt**f
?*f i*bl#«
op»ar
ladiaa
•l*«c
1210. «
70$ .9
2S(!i
111.0
70.0
St. Martin
• Irar
e
^
0
0
0
St. Hartla
*i**r
« .
0
0
0
0
St. Marti*
•!»•«
St. Karti*
«l»»f
101
Itl
lit
12*
121
a«k«n* \rwml mumm
Artificial
Lafooaa
17.00
12.40
It. 00
(.10
0.00
Artificial
M««OM
11. a
12.4
0.0
0.0
0.0
Artificial
Laieoaa
It.
0.
0.
0.
0.
Artificial
La •,•<>••
4100
1*20
1S40
147
(0
Dalawar*
11.
22.
t.
0.
0.
Ka»ai«ia7
Dwlanra
13.50
l.*4
0.00
0.00
0.00
••••InlHf
a*I*mt*
,42
,00
.00
•ft9
.00
MMialag
Otlaitaca
2S(*.
1140.
S24.
1S4.
74.
.— M
Nary laid
20.0
17.1
li.t
0.9
0.0
"•«!»•»<•
.as
.14
.00
.10
...
•a.ai.U,
•aiylaad
.05
.01
.00
.00
.00
iwl(IIM
•airlaad
127.000
93 . 700
4«.t*S
4.000
4.000
-------
D*l*n*c«/Maryl*ad Caaatal lays - 3.di««nt C6««litty 7»rl«bl«»
Muiaira. 7Sth P.rc.»til». Ptidiaa, 15th f>tcaBtila, Bad
a
t-i
o
gunatilax
KUUMWI
rcr 79*1
mntrn
rct_29n
a«aatil«a
ret 79f«
MOlABl
rex i9t8 -
aawtila.
MM MM
FCt 75T»
•colu
fC* JST»
nuxMm
f Of_T9t«
»C* 19M
MaTum
Katlr*
Tabulation
• ••0
a. «o
0.00
lotica
.41
.IS
.00
.00
.00
•attir*
t«palatian
OS404
S4400
SUM
12* ••
•atir*
4*1. •
«. i
' 4.4
ladiaa
tivar
t.174
4.241
1.900
1.004
4.000
ladiaa
•i**I
1.4*4
4. Ill
0.4*4
4. IN
0.400
Oppar
ladiaa
«i»ar
S7400
30409
JSS04
Oppar
15.44
1*.9I
7.43
4.40
0.44
St. lUrtia
»i**r
*
1
1
•
«t. Martia
1
•
1
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11.9
9.1
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-------
Ct*«iBB*. 73th Mrcantila, Median, 29tb ffarcantil*, and
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Kaxl««B, 75th f*rc>RtU«, Kadiaa, 2St» rarcaatil
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-------
Dalawara/Harylaad Coaxfc*! Bafa - Sadiaaat Ch«ai«try
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tabulation
2130.00
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15.70
14.50
10.10
2.07
0.00
-------
C»**t*l
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, isth r*xc«i>tii*,
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itasiaraa, 75th fareaatiia, Hadiaa, 25th r>ccti*bl*»M<>oc*ath«B* (ppb)
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-------
NVximiB, 75th >«te*Bfcil*, K«dlan. 29th r«rc*Bttl*. *•* Hiaimi*
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rcr
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Varlabla-Laad Ippn)
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-------
Dclavara/Harylaao' Coaatal Bayi - s«di»ant Chaaittcf Variable*
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gnaatilaa
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fadiaa »t. Martia Artificial
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-------
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.0*0
-------
0»l*w*r*/K»tyl*ed Cental 9tja - Stdlwal c_«»titry v.ri.bl**
IStb f«rc«»til«, K*diM, 2Stb r«rc»til«, >n
Intlr*
St. Kattia
NASIIKM
fCT TIT*
Mimfu
»cr isn
1.110
0.2S4
0.000
*.((0
4.0t4
.112
.(!(
• w l?y**f " ix in.,.,..,,,, _«_
krtlfieinl _**._iaiB9 ••••iaiBf
Ufoom D«l(H.ro __ryl«ni
1.111
«!ooo
(.000
(.000
.110
.000
.000
.000
V*Ti«bl«-rci Co«f*««t 107
Q*«ltil*(
MAXIMUM
re* ist«
HINM
Kf ZSTC
(•tit*
I-.i«a St. N-ctiB
111ft _i**f
.110
.1(2
.111
.080
.010
D
fe
tetir*
1.0(0
0.102
O.S21
0.400
o.eoo
«pp*c
lndi»a
ti»«t
St. Hattla
.11
.SO
.Oi
.00
.00
ippbi —
_rti(ici«l
0.1(20
O.(010
0.111S
0.0000
o.oooo
0.213
0.2S2
0.000
0.000
e.oeo
MUIMWI
tc*
f CT 2>T»
Minium
.(f
.10
.00
.00
.00
l.*fO
!.«»»
0.04S
0.040
0.000
1.210
0.(22
(.440
0.000
(.000
C.Bf«-*r
(ppb)
tadiu it. lUrtin *rti
-------
tuxiau, 7Jth r*rc*atil», lUdiaB, ZStk ••ccaatila, and Mialaua
N)
OJ
Qnaatiltt
HAZUWM
ret 7sn
MM?**
rcr an
MM?mm
«««Btil«.
•AIIHOH
.ret 7Sn
• HI&TABI
ret 1ST* . •
•xaTmrn
Quaatil**
•AinOM
ret 7sr»
MtoTlMi
ret_isn
"*"
guaatlUa
HAItnDH
ret 7SM
NIOTMI
ret ZST»
MI 11 HUH
Batica
rooolatloa
• .Ml
0.000
0.000
o.too
o.too
Batir*
rop«latl«a
u.ioo
0.<77
o.too
o.too
• .too
la t Ira
roaalatlM
.ito
.114
.too
.too
.000
fatlra
r«palati«a
is. too
1.4)0
t.zss
o.too
• .000
app.r
»l»«r
t.174
t.140
t.OOO
o.oot
0.000 ,
V«pl«klA
•^•*- «anaBA4
»l»ar
rCB COB9«B9K J
St. Hartia
•ivar
St. Hartia
»!»•>
» V«iri &•**!.•• PCS CoB*ivB*ir
tadiaa St. Hart la
»l»«r
•i»ar
.124
.114
-K1
.000
.000
ladiaa St. Hartia
Il»ar
.110
.4*1
.2SS
.too
.000
»i»«r
.SI
.St
.Jt
.to
.to
•» \rv*i —
Artificial
La.o.aa
>• i
Artificial
U««oa*
IS. 400
4.170
l.fCO
o.tos
.000
•••alaiao; 1
ixlavar*
t.SiJ
0.1*0
o.oot
0.000
o.oot
••aaiaiaf
IXlaoara
1.2700
1.94tO
0.1S7S
o.ooto
o.ooto
....iBi.,
IMlavar*
1.S70
0.417
0 .IOC
0.000
o.oot .
•aaaiaia
a«la«ara
.4SO
.441
.000
.000
.000
(••aloin?
Haifiaad
.200
.20C
.too
.••0
.••0
M«i.iB,
Harylaad
0.177
O.C41
0.000
t.ooo
t.too
•••aialaf
Harylaad
•••alaiaf
Haryla.d
0.1J1
0.000
o.too
o.ooo
0.000
-------
O»l«w«E»/M«iyl»nd Ctilttl l«r> - Sal>nrl*B* (PP»
muaum
nrr im
fct 2sn
•a tic*
121.
«.
3S.
0.
•l**r
121.
11».
22.
1*.
0.
St. lUrti*
•l*«c
11
11
0
0.
0,
Jtctificinl
121.0
is.i
0.9
Ml«i»c*
111.00
S4.10
13.39
0.00
0.00
OS.
•1.
f.
0.
*.
gocntilo
atii*
fC*_7SW
fCt 25tl.
32*.
7*.
It.
11.
»§»»*
SB41*B
•lv*r
11.5*
<«.so
lo.ta
13.1*
2.*1
St. Hart ill Artificial MMlalaf
12*.
tl*.
11.
21.
It.S
lt.5
17.1
11.1
17.1
12.*
2l!s
13.7
0.0
•••alai*f .
•Utylaad
70.
11.
20.
0.
0.
-------
D«la«aca/ltaryl*ad Coastal Bays - s*aia*nc ca*Bincy yafi«O4«>
Haiiaua, 75th r*re«ntil«, Madina. ISth t*cc*Btll*, and Mini«u»
guatilt*
vet 7ii»
tCT 2STI
MlBfmm
tatif*
reputation
1211.0
IS1.0
11.1
12.*
I.I
«pp-r
Indian
*lv*r
121.
19.
$1.
12.
Vati*bla»Pfr*a*
.1*1
.000
.400
Dclavaca
1.11
1.10
1.13
I. II
0.10
•••ainlng
Nacylaad
3
9
t
9
Ul
guantilai
tCT 7STB
MIDful
utilrnm
•ntir*
ropulation
14.184
l.«41
I.MS
I. Ml
0.000
Upp.r
M41«H
7.111
lillf
*1*
1.
1.
I.
I.
tin
Attifielal
D*lavarg
11.11
4.11
2.M
0.00
4.10
Harrland
1.4*00
3.31*0
1.54*5
0.4»»»
4.4440
••til*
HUIHOH
tcr ...
MtlTjUl
• VCt lit!
21.700
10.100
*.OIS
2.714
• .Oil
Xadl*B
Bl»ar
u.sao
S.1«S
1.040
at. Martin
li»ar
.170
.170
.1*1
.010
.000
Artificial B*B*i
11.10
11.71
I.M
D«lavar*
21.7
21.7
11.7
1.0
1.0
**aaiaiB|
Maryland
11.4000
11.7000
1.4701
I.4701
4.0440
-------
D«l«««r«/K»ryl«»d Ca«»t*l
HiiiIUK, 15th »4rc«atll«, HtdiaD, JSth »«tc«otll«
»tciibl«.JZH - Mlcktl tpp«(
guintilti
ICl 7Sf»
MDIMI
tC« 3STH
NIHIHUH
KBtir*
apvlctio
11.2*0
t.1«0
0.809
»iv«r
.790
.1*5
. 19S
.140
St. Hirtia
Bi«*c
2.24
2.24
2.0*
l.fl
1.12
ActiCici.l
11.2*
f .42
l.K
2.30
0.00
D*l*v*r«
4.t2
o.oo
0.0*
•••titling
-ISO
.t*0
.its
.000
.000
— V>ri«bl*-5CH - line l;;m)
Ou«etil«i
luunmrn
»CT ISM
rcr
NIBIHUH
D
Knttr*
ropulttlo*
114.100
2t.700
4.195
Iatlr«
Indian
»lv»r
4*.00
41.1*
12.IS
1.14
St. ««ctio
«tv»c
14.10*
10.41S
«.SJO
«.530
92.00
40.10
11.20
2f.40
4.1*
••••iaiaq
114.00
114.00
t.SI
O.S7
Mfflciid
31.700
JI.I50
14.170
4.145
l.SSO
WXIHM
tCI 7SM
tec isw
*ninnt
.ISM
-35J5
.!*•*
.3778
.J47S
Jt»5
.IMS
.8099
.»30
.«>!
.4*2
.100
.40*
D*l***c*
1.154
t.Sll
t.tia
a.no
0.0*0
.(44
.«S7
.144
.000
.00*
latlr*
,„.,
St. Hactin Attifial*!
itAximn
rex ivn
BtOJA*
fCT JSTI
Ht»Tmm
.2710
•.!>.?•
-<14S
.«J1«
. otao
0.2t««
«.1»*0
a. tut
.OS4S
.OI4S
.*44S
.014S
.0345
0.2710
0.11SO
t.UJO
ft. 01 14
-t'OMO'
.0*12
.07)2
.0404
.0*00
.0000
0.1120
4.4141
O.OKS
0.020)
"0.0000
-------
Dclavira/Marylind Caaital iay» - Sa4i»a«t c»«»ntrj Ta
Haniaua, llta farcMtil*. Hadian, 25ta raicaatila, ««d
feiaatilca
RAZIHOa
ici 1MB
usafM
ret ist«
airfMim
ftattttlla*
•mum
»et IStB
Miefjui
ret »«•
•irfnini
Ouaatilaa
Mutunm
ret isn
MIDtAI
ret 2 STB
nmfwm
g«aatil*a
HAXIHVH
ret 1st*
MBf**
»CT JSl*
NtBliMMt
fotir*
Population
l.M
J.S1
t.tl
1.11
...
(•tit*
roaalatloH
4 11. JO
*i.l*
SI.**
2.*4
ladian
«ivar
J.JfO
2.110
l.<0f
1 .*tl
• .111
*^^ Taclab]
ladiae
•i»*r
4i«: 2*
121.4*
114.**
1*. »«
*•( i< mo mW*Hf 4 1* 1|
St. (urtia
•i**r
.lit*
.11**
.*1H
.I4S*
.14*0
St. Martin
• i*ar
*.**' 12. M
Intlra
Population
1*11. ««
11 I.JO
ll! 10
0.00
In lira
Poaalatiaa
4710.
411.
19*.
12.
•
~~-~~ V«» »«W»W~» Wfc»* «^«*H^
ladiaa St. Hartia
li»ar
135.10
ill.l*
11.1*
11.1*
12.14
ladiaa
*i**c
114.1
21f .1
111.1
S1.S
42.1
«i»ar
11.9
11.1
11.1
11.1
11.1
St. Hartia
•Ivor
ts.s
*S.9
74.1
Sl-1
SJ.i
p>,
Artificial
I*«a«B(
.»«
.il
.It
.21
.*•
*&Ka laaal «-
rmmrn lira'0!
Artificial
Laaooaa
1J4.19
11*!**
27!it
0.**
Artificial
«•»*>»»•
1001.00
211. f*
114.1*
SS.7I
!*.««
fuim faabl
Artificial
Mf«aa*
414*. «
1*91.*
S34.C
111.4
in. 2
•••aiaiaf
••lanaxa
LSI*
j.ua
l.tIO
«.12*
t.sii
••••iaiaf
D*lav«r<
**.«•*
14. S**
1*.*49
2.*4*
*.***
•••aialn9
Balavaca
111.2*0
11.10*
11.149
11.19*
*.***
.«.i.ia,
txlavara
4*1.*
1SI.S
f 1 . 1
*.*
1.0
**Mialaf
Mairlaad
.III
.
-------
— 3«k)
Oaantllai
•UUBM
pet 7in
HtDljUl
KI l»»«
•nftBM
••tic*
aa It. Martin Artificial
li**r I^foaaa
1*7.40
1J.49
f.M
••naiaiaf
D*lanar«
147.44
01.1*
14.**
0.44
• .00
••aataiai
7J.
17.
0.
0.
0.
gvaatilai
Huimm
9& 7SYV
NtDfM
HTT ISt*
Hiifjom
latita
ragnlation
11.110
1.414
(.411
0.000
(.0(0
~~"^ 'W*cai
«t>*'
Indian
•ivar
a. cio
1.444
1.101
O.OS2
(.IT*
Varithlc-Tatal Cnloritaaa
St. lUrtlB
.4»4t
.4tO«
.447*
.low
.MM
artificial
Lafa«a«
S.S7S
3.411
2.411
1.540
4.444
0*l«ara
11.120
0.410
4.404
o.ooo
•anaiaiaf
Hatylaad
0.4*1
0.000
0.000
0.000
4.404
-------
• , 7St.li P*rc«Btll*, H*di*B, 35th r>«rc»atil», and Miaina
Variabl«»*»tal BDO
Intif*
Qaaatilo
HUIHOH
VO IS**
MIDIA*
ret 2STC
11.110
2.***
4.S7*
0.404
*.*«*
I«di«a
»40
.**4
.112
.4*2
.««*
St. Hurtilt
artificial
10 . 740
4.SW
I.ltt
i. ail
*.1T*
Dolavac*
ll.lt*
1.011
«.*«*
0.00«
•••aiaiaf
.SSI
,4**
.!*•
-•*•
tatit*
— »«riattl«-Tatal DDI (ppk)
Artificial
(*!»•«
lBdi»B
luximm
re* isn
HXOIM
ret Mia
mrfmm
IT.It
1.S1
1.14
0.00
o.«o
l.it*
1.117
St. H*rtin
llv*c
l.«40
t.lll
1.149
t.T«4
1.01*
D*l«M«r«
11.110*
J.4S44
1.ITSS
4.0000
4.40*0
1.170
1.149
I.S4T
O.MI
o.ooo
iBtlt*
W«ria»l«^Iot«l OUT (ppfc)
«ta*c
•i
-------
Balauart/naryland Coattal lays - Sadiaaat chaaittry Tariaklaa
•aslaua, 7Stb tarcaatil*, Hadian, 25tb Farcaatila, aid niaiava
Quaatila*
MAXIMUM
»CT 7St»
BfOTA"
ret 2STK
NXMXNON
• • ' • TBH
Cati ca
repulatioa
**(!.
1*7.
110.
74.
•DAavroca* •
Uppar
Indiao
»i»ar
1(7.00
(7* .*0
1*0.00
10*. 45
0. 74.10
m a .k« •-* . t
Uppar
latira Indian
Qnaatllaa
MAXIMUM .
ret 7ST«
HCOTJUI
tCT 25TH
MuTmm
ropulatloa
1115.*
107.5
111.1
10.*
0.0
•i»«r
552.
24(.
1*1.
04.
44.
iign noAwcvAac
St. Hactia
«i**r
1*1.7
1*1.7
147.1
112.5
112.5
Low Holacular
St. Martla
»lT«r
11.5
ll.S
17. (
17.1
17.1
n»Lv • I.TI } .i._-.. njiui r U__.-I.IL U.._L-.I__ Variabla*Total OFD
Upper
quaatllaa
MAXIMUM
»Ct 7Sn
HCBIAB
tcr 2sn
NintNm
Quaatllaa
MAXIMUM
ret 7Sn
HKDiA*
rcT tvn
NlflTHOM
latira
•«pulntlea
.(00
.0*0
.417
.000
Indian
»l»ar
.070
.741
.2*0
.7(7
*t. Hart In
tl*ar
.000 .000
_____•_______ "• — *-•-• — •_»._«
-------
Haiiaua, 75tb Parcantila. Madiaa. 25th Parcaatlla, aad Nioiaoa
Vatiabla»Tetal PABa (ppb)
Uppar
tntlr*
gvaatllai
MAtXMM
Per 7STC
HIOtA*
per 25TC
MlnTMOH
107S.10
402.20
154.15
0.00
1115.40
•51.10
0«0. SO
15*.70
154.15
*t. Martin
•ivar
100.
100.
1*4.
14*.
14*.
Artificial
La«ooa«
101*«.«0
114*.00
110«.S4
01S.20
«00.00
Oalavara
1204.00
574.1«
11*.11
i*.10
1.04
Maryland
402.20
101.it
105.70
0.00
0.00
pc»a (Sua| Ippb)
gaaatllaa
MAIIMm
PCT ittn
HIOfAl
per 25TH
Hiilmm
liitlra
Popolatlon
47.257
5.001
0.040
0.000
Oppar
India* *t. Martin Artificial
«l»«r «i»«r lafaea*
15.151
1J.J7*
*.oii
0.140
1.114
1.114
1.71*
0.124
0.124
47.2S7
21.171
14.100
*.2S1
0.72*
Dalavara
11.ISO
*.!!«
S.<14
0.000
0.000
Harylaad
.001
.*«7
.414
.000
.000
O —
KMIIHail
PCf 75TC
MMt?M
»« "«
HialHim
Papalatloa
20.400
1.020
i.oos
0.402
— Varlabla»Tatal
St. Martin
•Ivar
Ippb)
.002
.170
.040
.774
Artificial
Lagoaaa
.170
.010
.0(4
*«02
Dalanara
20.400
0.220
1.1*1
• •••0
0.900
namalala*
Maryland
.0(0
.015
.000
.000
IPPb)
gnantllaa
MAXIMUM
PCT 7STM
HIotAal
PCT 1ST*
matmm
fatic*
Papalatiaa
.110
.040
.205
.000
.000
tfppar
adiaa it. Martia
«i»ar Ei»ar
.140
.152
.721
,000
.000
O.f*00
0.1*00
0.4475
0.1050
0.1050
Artificial
Lafaeaa
l.«5«
1.1*0
0.041
O.«ll
o.ooo
Oalawar*
l.li
0.41
0.00
0.00
0.00
lanalaliifj
Maryland
-------
D*ia«ar*/Kicyland Coastal oaya - 4a4i««it Cnaniatcy Variablat
Maciamn, 15th rarctatlla, Hadian, ISth farcantlla. and Minlun
gnantilaa population
Dpp.r
Indian
St. Martin
»i»ar
Artificial
Lifvonl
MAXXMOM
FCT 7STB
MBQlM
ffCT 2SWI
MIMMOM
1S3.000
4.I4S
0.000
0.000
0.080
1S1.00
15.00
e.«a
•••ainin;
Maryland
SC.
It.
0.
0.
0.
— 9ariaBlanZine (pp»)
latiri
Quant11aa
HAXIMOH
FCT 7St»
MCD¥MI
HHUWN
140.00
K.30
32.10
(.If
Indian
•ivar
140.
13*.
12(.
S2.
2t.
St. Martin
kl**r
13.00
11.00
11. SS
12.10
32.10
Artificial
145.
131,
114,
41,
12,
•anaiainf
Oalavara
U(.00
(9. (5
11. TO
!.((
Kanaininf
Maryland
11.30
It. 10 .
22.00
(.1*
o
gviatilai
HA2IMDH
FCT 7»TB
KMIAM
FCT IStB
MIIIHUH
In* in
4.11
1.12
0.00
«.oo
0.00
Indian
1.41
1.22
1.12
0.00
0.00
mo,p, BOD (Mb) —
St. Martin
*i**t
0
0
0
a
o
Artificial
4.170
3.200
1.010
0.(24
0.009
BaMining
Oaiawara
2.SIC
0.1(0
0.000
0.000
0.000
•waiainf
Maryland
0
0
o
0
— v«ri«bU-o,p. OBI (ppb) —
Quant ilaa
MAXIMUM
•CT
»cr «*•
NIllMttM
tatica
tefulatlon
.(f(
.Iff
.127
.00*
.00*
Indian
•l*ar
l.(l
1.1*
l.M
0.08
0.00
St. Martin Artificial
»i»«r bafoona
2. (40
1.S10
l.l«0
0.1(4
0.000
•aaiaiainf
D*la»ara
.MO
.1(7
.000
.000
••naininf
Maryland
.000
.000
.OOO
.000
-------
gttaatilea
MAXIMUM
per 7SW
•BD-AV
per 2Sn
•Miami
Oneatilea
MAXIMO*
per 7ST>
MCBIAM
PCT_21T«
•nunM
Oaaatilaa
MAXIMDH
rCT 71TB
HtoTAM
rcr 2 IN
nxailmm
Quant lie*
MAXIHim
rcr 75ti
HIDIAJI
ret 2 STB
Haiiaaa, 75th
let ire
reputation
2.970
0.131
(.400
(.(((
(.(((
Batire
Pepalatlea
.(((
!»7(
.114
.(((
.,.,
Satire
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APPENDIX E
Benthic Macroinvertebrate Survey
of Turville Creek, Maryland
E-1
-------
One of the benefits of the coastal bays project was
the identification of baseline conditions which
were established using consistent methods across
the entire system. This baseline allows for a
rigorous, statistically-based evaluation of local
issues, based upon comparison to a broader
reference condition than can be achieved with the
resources typically allocated to evaluation of local
issues.
EPA Region HI recently availed itself of that
benefit to evaluate current benthic
macroinvertebrate conditions in Turville Creek, a
small tributary to Assawoman Bay. Residential
development, including construction of artificial
lagoons, has been proposed for that area. On 14
September 1994, 25 benthic invertebrate samples
were collected in Turville Creek by W. Muir of
EPA Region III using the same sampling design,
field methods, and laboratory methods that were
used in the coastal bays joint assessment. A
summary of those sample results are presented
here.
Turville Creek was found to be in poorer condition
than the coastal bays as a whole, but in better
condition than artificial lagoons that have already
been constructed in the coastal bays. The average
number of species collected per grab in Turville
Creek was almost two-thirds less than in the
remaining coastal bays, but was more than twice
that in artificial lagoons (Table E-l). Invertebrate
abundance was about one-sixth that in the
remaining coastal bays, but twice that of artificial
lagoons. Biomass was 50 times lower than in the
coastal bays, but not significantly different from
the artificial lagoons (Table E-l).
Based on EMAP's benthic index (Schimmel et al.
1994), 60% (± 9) of the area in Turville Creek
was estimated to have degraded benthic
invertebrate communities. This was twice the
percent of area containing degraded benthos in the
rest of the coastal bays (28% ± 8), but
significantly less than that for artificial lagoons
(85% ±16).
E-2
-------
CO
Appendix Table E-l. Area-weighted means of benthic macroinvertebrates parameters (90% confidence intervals)
Abundance (#/m2)
Biomass (g/m2)
Number of Species (^/sample)
Shannon-Wiener Index
EMAP Index
Entire Population
18.724 ± 2,551
10.57 ± 3.03
24.25 ± 1.19
2.73 ± 0.10
0.48 ± 0.25
Artificial Lagoons
1,917 ± 1,354
0.43 ± 0.33
3.6 ± 2.6
0.59 ± 0.49
-0.57 ± 0.25
TurviUe Creek
3,111 ± 627
0.29 ± 0.09
8.76 ± 1.39
1.68 ± 0.31
-0.10 ± 0.14
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