SEPA
United States
Environmental Protection
Agency
Ecological Condition of Coastal Ocean Waters
Along the U.S. Mid-Atlantic Bight: 2006
NOAA Technical Memorandum NOS NCCOS 109
EPA 600/R-09/159 | December 2009 | www.epa.gov/ord
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NOAA Technical Memorandum NOS NCCOS 109
Ecological Condition of Coastal Ocean Waters Along
the U.S. Mid-Atlantic Bight: 2006
December 2009
Office of Research and Development U.S. Department of Commerce
U.S. Environmental Protection Agency National Oceanic and
Washington, DC 20460 Atmospheric Administration
National Ocean Service
Silver Spring, MD 20910
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Ecological Condition of Coastal Ocean Waters
Along the U.S. Mid-Atlantic Bight: 2006
December 2009
Prepared By
W. Leonard Balthis1, Jeffrey L. Hyland1, Michael H. Fulton1, Edward F. Wirth1, John A.
Kiddon2, John Macauley3
Author Affiliations
1 Center for Coastal Environmental Health and Biomolecular Research
National Oceanic and Atmospheric Administration
219 Fort Johnson Road
Charleston, SC 29412-9110
2 U.S. Environmental Protection Agency
ORD/NFffiERL Atlantic Ecology Division
27 Tarzwell Drive
Narragansett, R.I. 02882
3 U.S. Environmental Protection Agency
ORD/NFffiERL Gulf Ecology Division
1 Sabine Island Drive
Gulf Breeze, FL 32561
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Preface
This document presents the results of an assessment of ecological condition and potential
stressor impacts in coastal-ocean waters of the mid-Atlantic Bight (MAB), along the
eastern U.S. continental shelf from Cape Cod, MA to Cape Hatteras, NC, based on
sampling conducted in May 2006. The project was a collaborative effort by the U.S.
Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric
Administration (NOAA). It represents one of a series of studies, similar in protocol and
design to EPA's Environmental Monitoring and Assessment Program (EMAP) and
subsequent National Coastal Assessment (NCA), which extend these prior efforts in
estuaries and inland waters out to the coastal shelf, from navigable depths along the
shoreline seaward to the shelf break (approximate 100 m depth contour).
The appropriate citation for this report is:
Balthis, W.L., J.L. Hyland, M.H. Fulton, E.F. Wirth, J.A. Kiddon, J. Macauley. 2009.
Ecological Condition of Coastal Ocean Waters Along the U.S. Mid-Atlantic Bight: 2006.
NOAA Technical Memorandum NOS NCCOS 109, NOAA National Ocean Service,
Charleston, SC 29412-9110. 63 pp.
Disclaimer
This document has been subjected to review by the National Health and Environmental
Effects Research Laboratory of EPA and the National Ocean Service of NOAA and
approved for publication. Approval does not signify that the contents reflect the official
views of these agencies, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
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Acknowledgments
This study was made possible through the coordination of resources and staff under a
General Collaborative Agreement (MOA 2005-003/6764) between the NOAA National
Ocean Service's (NOS) National Centers for Coastal Ocean Science (NCCOS) and the
EPA Office of Research and Development (ORD)/National Health and Environmental
Effects Research Laboratory (NHEERL). Funding was provided primarily by the
NOAA/NCCOS Center for Coastal Environmental Health and Biomolecular Research
(CCEHBR) to support field work and by EPA/NHEERL-Gulf Ecology Division for the
processing of samples. Field work was conducted on the NOAA Ship Nancy Foster
Cruise NF-06-06-NCCOS by scientists from NOAA/NCCOS/CCEHBR, EPA/NHEERL-
Gulf Ecology Division, U.S. Geological Survey, and EPA/NHEERL-Atlantic Ecology
Division. Several institutions participated in the processing of samples. These included
Barry Vittor and Associates (Mobile, AL) for the analysis of benthic samples; GPL
Laboratories (Frederick, MD) for chemical contaminants in sediments; and B&B
Laboratories (College Station, TX) for nutrients and chlorophyll in water samples, and
sediment grain size and TOC. Fish samples for analysis of chemical contaminants were
provided through coordination with bottom-trawl surveys conducted by the NOAA
Fisheries Service/Northeast Fisheries Science Center (Woods Hole and Narragansett
labs). Analysis of contaminants in fish tissues was performed by
NOAA/NCCOS/CCEHBR in-house staff. Special appreciation is extended to Harry
Buffum (Raytheon, contractor to EPA) for summary and analysis of the EPA 2005-2006
National Coastal Assessment (NCA) estuarine data, used for comparison with the MAB
2006 results presented herein.
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Table of Contents
Preface ii
Acknowledgments iii
List of Figures vi
List of Tables vii
List of Appendices viii
List of Acronyms ix
Executive Summary x
1.0 Introduction 1
2.0 Methods 3
2.1 Sampling Design and Field Collections 3
2.2 Water Quality Analysis 6
2.3 Sediment TOC and Grain Size Analysis 6
2.4 Sediment Contaminant Analysis 6
2.5 Fish Tissue Analysis 7
2.6 Benthic Community Analysis 7
2.7 Quality Assurance 8
2.7.1 Quality Assurance and Quality Control 8
2.7.2 Water Quality Analyses 8
2.7.3 Sediment Contaminant Analyses 8
2.7.4 Benthic Taxonomy 9
2.7.5 Tissue Contaminant Analyses 10
2.8 Data Analysis 10
3.0 Results and Discussion 14
3.1 Depth and Water Quality 14
3.1.1 Depth 14
3.1.2 General Water Characteristics: Temperature, Salinity, Water-Column
Stratification, DO, pH, TSS 16
3.1.3 Nutrients and Chlorophyll 20
3.2 Sediment Quality 22
3.2.1 Grain Size and TOC 22
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3.2.2 Chemical Contaminants in Sediments 23
3.3 Chemical Contaminants in Fish Tissues 29
3.4 Status of Benthic Communities 34
3.4.1 Taxonomic Composition 34
3.4.2 Abundance and Dominant Taxa 37
3.4.3 Diversity 38
3.4.4 Non-indigenous Species 48
3.5 Potential Linkage of Biological Condition to Stressor Impacts 48
4.0 Literature Cited 50
5.0 Appendices 56
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List of Figures
Figure 1. A. Map of study area and station locations. B. Map showing location of 2007
NFS/NEFSC trawl locations used for fish tissue contaminant analysis.
Figure 2. Percent area (and 95% confidence intervals) of MAB shelf waters vs. selected
water-quality characteristics.
Figure 3. Percent area (and 95% confidence intervals) of MAB shelf waters vs. nutrient,
chlorophyll, and TSS concentrations.
Figure 4. Map of study area showing distribution of DIN in bottom water.
Figure 5. (A) Percent area (and 95% CI) represented by varying levels of the % silt-clay
content of sediment, and (B) percent area having silt-clay content within specified ranges.
Figure 6. (A) Percent area (and 95% CI) represented by varying levels of TOC content of
sediment (mg/g), and (B) percent area having TOC content within specified ranges.
Figure 7. Map of study area showing distribution of total DDT in sediments.
Figure 8. Comparison of contamination in MAB shelf sediments (2006, this study) vs.
estuaries of the Virginian Province (NCA 2006).
Figure 9. Distribution of PCB concentrations in fish tissues (fillets) relative to EPA
(2000a) non-cancer human-health guidelines.
Figure 10. Relative percent composition of major taxonomic groups expressed as percent
of total taxa (A) and percent of abundance (B).
Figure 11. Percent area (and 95% C.I.) of MAB shelf waters vs. benthic infaunal
taxonomic richness (A), density (B), and H' diversity (C).
Figure 12. Comparison of (A) benthic taxonomic richness (mean # taxa/0.04 m2), (B)
density (mean # individuals/m2), and (C) diversity (mean HV0.04 m2) among inner,
middle, and outer shelf locations.
Figure 13. Trends in mean densities (#/m2) of dominant taxa collected in sediments from
relatively shallow (< 30 m) inner-shelf waters to deeper mid- (30 - 50 m) and outer- (>
50 m) shelf waters of the MAB.
Figure 14. (A) Spatial distribution of benthic taxonomic richness (mean # taxa/0.04 m2);
(B) Spatial distribution of benthic infaunal density (mean # individuals/m2); and (C)
Spatial distribution of benthic taxonomic diversity (mean H70.04 m2).
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List of Tables
Table 1. Thresholds used for classifying samples relative to various environmental
indicators.
Table 2. ERM and ERL guideline values in sediments (Long et al. 1995a).
Table 3. Risk-based EPA advisory guidelines for recreational fishers (USEPA 2000a).
Table 4. Summary of depth and water-column characteristics for near-bottom (lower 3
m) and near-surface (0.5 - 4 m) waters.
Table 5. Summary of sediment characteristics.
Table 6. Summary of chemical contaminant concentrations in sediments.
Table 7. Summary of contaminant concentrations (wet weight) measured in tissues of
summer flounder, P. dentatus.
Table 8. Summary of major taxonomic groups of benthic infauna and corresponding
numbers of identifiable taxa in samples from shelf waters of the MAB compared to
northeastern estuaries.
Table 9. Mean, range, and selected distributional properties of key benthic variables.
Table 10. Fifty most abundant benthic taxa in the MAB 2006 survey region-wide.
Table 11. Fifty most abundant benthic taxa collected in northeast estuaries.
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List of Appendices
Appendix A. Locations (latitude, longitude), depth, and sediment characteristics of
sampling stations.
Appendix B. Near-bottom water characteristics by station.
Appendix C. Near-surface water characteristics by station.
Appendix D. Summary by station of mean ERM quotients and the number of
contaminants that exceeded corresponding ERL or ERM values (from Long et al. 1995a).
Appendix E. Summary by station of benthic macroinfaunal (>0.5mm) characteristics.
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List of Acronyms
CDF Cumulative Distribution Function
Chi a Chlorophyll-a
CTD Conductivity-Temperature-Depth
CVAA Cold Vapor Atomic Absorption
CWA Clean Water Act
DDE Di chl orodiphenyl di chl oroethyl ene
DDT Di chl orodiphenyltri chl oroethane
DIN Dissolved Inorganic Nitrogen
DIP Dissolved Inorganic Phosphorus
DIN:DIP Ratio of DIN to DIP
DO Dissolved Oxygen
EAM Ecosystem Approach to Management
EMAP Environmental Monitoring and Assessment Program
EPA Environmental Protection Agency
ERL Effects Range Low
ERM Effects Range Median
GC/MS Gas Chromatography/Mass Spectrometry
GED Gulf Ecology Division
GFAA Graphite Furnace Atomic Absorption
GRTS Generalized Random-Tessellation Stratified
IEA Integrated Ecosystem Assessment
ICP-MS Inductively Coupled Plasma-Mass Spectrometry
LME Large Marine Ecosystem
MAB Mid-Atlantic Bight
MIT Massachusetts Institute of Technology
MITIS Marine Invader Tracking Information System
NBI National Benthic Inventory
NAS Nonindigenous Aquatic Species
NCA National Coastal Assessment
NCCOS National Centers for Coastal Ocean Science
NEFSC Northeast Fisheries Science Center
NEMESIS National Exotic Marine and Estuarine Species Information System
NHEERL National Health and Environmental Effects Research Laboratory
NM Nautical Mile
NMFS National Marine Fisheries Service
NOAA National Oceanic and Atmospheric Administration
NOS National Ocean Service
PAH Polycyclic Aromatic Hydrocarbon
PBDE Polybrominated Diphenyl Ether
PCB Polychlorinated Biphenyl
PSU Practical Salinity Units
SAB South Atlantic Bight
SEE Seabird Electronics
SQG Sediment Quality Guideline
TOC Total Organic Carbon
TSS Total Suspended Solids
USGS United States Geological Survey
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Executive Summary
In May 2006, the NOAA National Ocean Service (NOS), in conjunction with the EPA
National Health and Environmental Effects Laboratory (NHEERL), conducted an
assessment of the status of ecological condition of soft-bottom habitat and overlying
waters throughout the mid-Atlantic Bight (MAB) portion of the eastern U.S. continental
shelf. The study area encompassed the region from Cape Cod, MA and Nantucket
Shoals in the northeast to Cape Hatteras in the south, and was defined using a one
nautical mile buffer of the shoreline extended seaward to the shelf break (~100-m depth
contour). A total of 50 stations were targeted for sampling using standard methods and
indicators applied in prior NOAA coastal studies and EPA's Environmental Monitoring
and Assessment Program (EMAP) and National Coastal Assessment (NCA). A key
feature adopted from these studies was the incorporation of a random probabilistic
sampling design. Such a design provides a basis for making unbiased statistical estimates
of the spatial extent of ecological condition relative to various measured indicators and
corresponding thresholds of concern. Indicators included multiple measures of water
quality, sediment quality, and biological condition (benthic fauna). Through
coordination with the NOAA Fisheries Service/Northeast Fisheries Science Center
(NFS/NEFSC), samples of summer flounder (Paralichthys dentatus) also were obtained
from 30 winter 2007 bottom-trawl survey stations in overlapping portions of the study
area and used for analysis of chemical-contaminant body burdens.
Depths ranged from 14 - 98 m throughout the study area. About 92 % of the area had
sediments composed of sands (< 20 % silt-clay), 6 % of the area was composed of
intermediate muddy sands (20 - 80 % silt-clay), and 2 % of the sampled area consisted of
mud (> 80 % silt-clay). About 92 % of the area had sediment TOC concentrations < 5
mg/g and all sites had levels of TOC < 20 mg/g, which is well below the range
potentially harmful to benthic fauna (> 50 mg/g).
Surface salinities ranged from 30 to 35.3 psu, with the majority of the study region
(approximately 80 % of the area) having surface salinities between 31 and 33 psu.
Bottom salinities varied between 30 and 35 psu, with fewer sites (representing about 65
% of the area) having bottom salinities between 31 and 33 psu. A greater number of sites
(about 31 % area) had salinities > 33 psu in near-bottom waters compared to the surface
(10 % area). Surface-water temperatures varied between 7.8 and 17.9 °C, while near-
bottom waters ranged in temperature from 6.5-15.2 °C. The coldest bottom-water
temperatures were recorded in the area of the "cold pool", an area of colder, low-salinity
water originating in the Gulf of Maine and Georges Bank that flows around Cape Cod
and south-westward along the shelf. An index of density stratification (Aot) indicated
that the waters of the MAB shelf were well-mixed at the time of sampling, with no
evidence of strong water-column stratification.
Levels of dissolved oxygen (DO) were confined to a fairly narrow range in surface (7.7 -
9.7 mg/L) and bottom (8.1 - 9.9 mg/L) waters throughout the survey area. These levels
are within the range considered indicative of good water quality (> 5 mg/L) with respect
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to DO. None of these waters had DO at low levels (< 2 mg/L) potentially harmful to
benthic fauna and fish.
Total suspended solids (TSS) in surface waters ranged from 0.9 - 13.5 mg/L, with
slightly higher values observed in bottom waters (1.1- 36.4 mg/L). One site at the
entrance to Delaware Bay had concentrations of bottom-water TSS of 36.4 mg/L, with all
remaining sites having values < 16.3 mg/L.
Dissolved inorganic nitrogen (DIN: nitrogen as nitrate + nitrite + ammonium) in coastal
shelf surface waters of the MAB ranged from 0.01 mg/L to 0.20 mg/L and averaged 0.04
mg/L. Bottom water concentrations of DIN tended to be higher than surface DIN
concentrations, particularly along the outer shelf. This observation is consistent with
other published descriptions of the MAB, which have found nutrient levels to be higher
in bottom waters than in surface waters. In comparison to these offshore waters, estuaries
of the region tend to have higher levels of DIN, with values ranging from 0.01 - 3.0 mg/L
in surface waters and averaging 0.17 mg/L (NCA 2006). Similarly, bottom-water
concentrations of DIN in estuaries ranged from 0.01 - 2.2 mg/L and averaged 0.15 mg/L.
Concentrations of dissolved inorganic phosphorus (DIP) in surface waters of the MAB
ranged between 0.02 mg/L and 0.06 mg/L and averaged 0.04 mg/L. Bottom-water
concentrations of DIP were somewhat higher than those measured in surface waters,
ranging from 0.02 mg/L to 0.12 mg/L and averaging 0.05 mg/L. DIP concentrations in
MAB shelf waters were slightly higher than those observed in estuaries, but these levels
appear to be comparable to results from other studies in offshore areas of the MAB.
DIN:DIP ratios in surface waters ranged from 0.43 to 6.25, which are strongly indicative
of nitrogen limitation (DIN:DIP < 16). Surface-water concentrations of chlorophyll a, an
indicator of phytoplankton biomass and abundance, ranged from 0.01 |ig/L to 3.30 |ig/L
and averaged 0.23 |ig/L. Bottom-water concentrations of chlorophyll a were similar to
concentrations in surface waters, ranging between 0.01 |ig/L and 3.02 |ig/L and
averaging 0.3 |ig/L. Chlorophyll a concentrations in offshore waters were much lower
than in corresponding estuaries.
Shelf sediments of the MAB appeared to be relatively uncontaminated. No contaminants
were found in excess of their corresponding Effects-Range Median (ERM) sediment
quality guideline values. The entire survey region was rated in good condition (no
chemicals above corresponding ERM values and < 5 chemicals above corresponding
Effects-Range Low (ERL) values). Arsenic was one of only three chemicals that
exceeded their corresponding ERL guidelines. The ERL exceedances for arsenic
occurred at three sites, representing 6.3 % of the survey area. The overall range of
concentrations for arsenic was within the range typical of uncontaminated near-shore
marine sediments and reflects its natural presence at low to moderate concentrations in
crustal rocks of the region. Similarly, one site, representing 2.1 % of the study area, had
nickel concentrations that just exceeded the ERL value of 20.9 jig/g. Concentrations of
total DDT (sum of 2,4'-DDD, 4,4'-DDD, 2,4'-DDE, 4,4'-DDE, 2,4'-DDT, and 4,4'-DDT)
were detectable in sediment samples at eight sites and exceeded the ERL guideline of
1.58 ng/g at five sites, which represent 10 % of the study area. Total DDT levels were
below the limit of detection at all of the remaining 40 sites where sediment samples were
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collected. Many of the other chemicals measured in this study also were below method
detection limits.
Because none of the species offish targeted for chemical contaminant analysis were
collected on the core May 2006 survey, samples of summer flounder (Paralichthys
dentatus) were obtained from a subsequent winter bottom-trawl survey conducted
February 6 - March 2, 2007 by the NOAA Fisheries Service, Northeast Fisheries Science
Center (NFS/NEFSC) and used for this purpose. Fish samples were taken from 30
bottom-trawl locations in shelf waters between Sandy Hook, NJ and Cape Hatteras, NC.
Concentrations of a suite of metals, pesticides, and PCBs were measured in edible tissues
(fillets) of 30 individual summer flounder, one each from the 30 trawl sites, and
compared to risk-based EPA advisory guidelines for recreational fishers. None of the 30
stations where fish were measured had chemical contaminants in fish tissues above the
corresponding upper human-health endpoints. Thus none of these stations were rated as
"poor" with respect to contaminant body burdens. Three stations had total PCB
concentrations in tissues that were between the corresponding lower and upper endpoints
and thus were rated as "fair." All other stations had concentrations of contaminants that
were below corresponding lower endpoints and thus were rated as "good."
Benthic taxonomic richness was relatively high in MAB shelf assemblages, ranging from
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9-50 per 0.04-m grab and averaging 28 taxa grab" . Diversity (Shannon FT (Iog2))
averaged 3.4 overall, varying between 1.9 and 4.4 throughout the study area, and tended
to be higher among outer shelf sites compared to the inner shelf. A total of 3 81 taxa were
identified (215 to species) in 95 grabs collected during the course of the survey.
Polychaetes, crustaceans, and molluscs were the dominant taxa both by percent
abundance (46 %, 36 %, and 10 %, respectively) and percent of taxa (43 %, 31 %, and 19
%, respectively). Densities ranged from 675 - 29,263 m"2 and averaged 6,067 m"2.
The 10 dominant (most abundant) taxa, in decreasing order of abundance, included the
amphipod Ampelisca agassizi, the polychaetes Polygordius spp. and Acmira catherinae.,
tubuficid oligochaetes (Tubificidae), the amphipod Unciola irrorata, the polychaete
Spiophanes bombyx, the tanaid Tanaissuspsammophilus, the polychaetes Exogone hebes
and Goniadella gracilis., and maldanid polychaetes (Maldanidae). Some of these
dominant taxa (Polygordius spp., Acmira catherinae, Tubificidae, Tanaissus
psammophilus) were more abundant on the inner shelf compared to the middle and outer
shelf, while others (A. agassizi, U. irrorata, S. bombyx) were more abundant on the
middle and outer shelf. The composition of offshore assemblages was markedly different
from estuaries, with six of the ten offshore dominants either under-represented (found in
< 10 % of samples) or completely absent from estuaries. The reverse also was true, with
seven of the ten estuarine dominants being found either in low numbers (occurring in <
10 % of samples) or not at all offshore.
There were no non-indigenous species identified in samples collected in coastal shelf
sediments of the MAB, although some (Harmothoe imbricata, S. bombyx) are considered
to be cryptogenic, or of unknown origin. By comparison, a few cryptogenic
(Boccardiella ligerica, Monocorophium acherusicum) and non-indigenous (Branchiura
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sowerbyi, Corbicula flumined) benthic infaunal species were identified in samples
collected throughout mid-Atlantic estuaries as part of the U.S. EP A's National Coastal
Assessment in 2005-2006. The above estuarine non-indigenous species would not be
expected to occur offshore, however, since the shelf environment would be outside their
normal (lower) salinity ranges.
This study found no evidence of biological impacts linked to measured stressors. In fact,
no indications of poor sediment or water quality relative to published evaluation
thresholds were observed. These results suggest that coastal shelf waters of the MAB are
in good condition, with lower-end values of biological attributes representing parts of a
normal reference range controlled by natural factors. Some influence of depth on
diversity and taxonomic richness was observed, with deeper sites having slightly higher
values for these measures.
Alternatively, it is possible that for some of these sites the lower values of benthic
variables reflect symptoms of disturbance induced by other unmeasured stressors. In
efforts to be consistent with the underlying concepts and protocols of earlier EMAP and
NCA programs, the indicators in this study included measures of stressors, such as
chemical contaminants and symptoms of eutrophication, which are often associated with
adverse biological impacts in shallower estuarine and inland ecosystems. However, there
may be other sources of human-induced stress in these offshore systems, particularly
those causing physical disruption of the seafloor (e.g., commercial bottom trawling, cable
placement, minerals extraction), that pose greater risks to living resources and which
have not been adequately captured. Future monitoring efforts in these offshore areas
should include indicators of such alternative sources of disturbance.
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1.0 Introduction
The National Oceanic and Atmospheric Administration (NOAA) and the Environmental
Protection Agency (EPA) each perform a broad range of research and monitoring
activities designed to assess the status of coastal ecosystems and the potential effects of
natural and human impacts. Authority to conduct such work is given by several
legislative mandates including the Clean Water Act (CWA) of 1977 (33 U.S.C. §§ 1251
et seq.), National Coastal Monitoring Act of 1992 (Title V of the Marine Protection,
Research, and Sanctuaries Act, 33 U.S.C. §§ 2801-2805), and the National Marine
Sanctuary Act of 2000. To the extent possible, the two agencies have sought to
coordinate related activities through partnerships with states and other institutions to
prevent duplication of effort and to bring together complementary resources to fulfill
common research and management goals. Accordingly, in May 2006, NOAA and EPA
combined efforts to conduct a joint survey of ecological conditions throughout coastal
shelf waters of the mid-Atlantic Bight (MAB). The MAB lies between Cape Cod and
Nantucket Shoals to the northeast and Cape Hatteras to the south (Allen 1983) and is a
sub-region of the Northeast U.S. Continental Shelf Large Marine Ecosystem (LME), one
of 10 LMEs of the United States (U.S. Commission on Ocean Policy 2004) (Figure 1).
The present survey is part of a series of studies being conducted by NOAA and EPA to
assess the condition of aquatic resources throughout coastal-ocean waters of the U.S.
using multiple indicators of ecological condition. The protocols and design of these
studies are similar to those used in EPA's Environmental Monitoring and Assessment
Program (EMAP) and subsequent National Coastal Assessment (NCA), both of which
have focused mainly on estuarine and inland waters. The offshore series extends these
prior efforts onto the continental shelf, from approximately one nautical mile of the
shoreline seaward to the shelf break (~100-m depth contour). Where applicable,
sampling has been included in NOAA's National Marine Sanctuaries (NMS) to provide a
basis for comparing conditions in these protected areas to surrounding non-sanctuary
waters. To date such surveys have been conducted throughout the western U.S.
continental shelf, from the Straits of Juan de Fuca, WA to the U.S./Mexican border (see
Nelson et al. 2008 for final report); shelf waters of the South Atlantic Bight (SAB) from
Cape Hatteras, NC to West Palm Beach, FL (see Cooksey 2004 for cruise report); the
continental shelf off southern Florida, from West Palm Beach in the Atlantic Ocean to
Anclote Key in the Gulf of Mexico (see Cooksey and Hyland 2007 for cruise report);
and shelf waters of the mid-Atlantic Bight (MAB) from Cape Hatteras to Cape Cod, MA
(the present assessment). There are plans to continue these surveys throughout the
central and western portions of the Gulf of Mexico in summer 2010 and throughout the
remainder of the North Atlantic coast of the U.S., from Cape Cod to the Canadian border,
in 2011.
The purpose of the present study was to assess the current status of ecological condition
and stressor impacts throughout the MAB region and to provide this information as a
framework for evaluating future changes due to natural or human-induced disturbances.
To address this objective, the study incorporated standard methods and indicators applied
in previous coastal EMAP/NCA projects (U.S. EPA 200la, 2004, 2008) including
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multiple measures of water quality, sediment quality, and biological condition (benthic
community health and fish tissue contamination). Synoptic sampling of the various
indicators provided an integrative weight-of-evidence approach to assessing condition at
each station and a basis for examining potential associations between presence of
stressors and biological responses. Another key feature was the incorporation of a
probabilistic sampling design with stations (49 in total) positioned randomly throughout
the study area. The probabilistic sampling design provided a basis for making unbiased
statistical estimates of the spatial extent of condition relative to the various measured
indicators and corresponding thresholds of concern. Other surveys in the current coastal-
ocean series have applied stratified random sampling designs, with stations stratified by
NMS vs. non-sanctuary status. However, the boundaries of the present MAB study did
not encompass NMSs, thus the assessment of condition relative to these various
indicators did not include sanctuary vs. non-sanctuary comparisons.
Because the protocols and indicators are consistent with those used in previous
EMAP/NCA estuarine surveys, comparisons can be made between conditions in offshore
waters and those observed in neighboring estuarine habitats, thus providing a more
holistic account of ecological conditions and processes throughout the inshore and
offshore resources of the region. Such information should provide valuable input for
future National Coastal Condition Reports, which historically have included limited
coverage in offshore areas (e.g., U.S. EPA 2001a, 2004, 2008).
Results of this study should also provide valuable support to evolving interests within the
U.S. and other parts of the world to move toward an ecosystem approach to management
(EAM) of coastal resources (Murawski 2007; Marine Ecosystems and Management
2007). Integrated Ecosystem Assessments (lEAs) have been identified as an important
component of an EAM strategy (Murawski and Menashes 2007; Levin et al. 2008, 2009).
An LEA is a synthesis and quantitative analysis of information on relevant natural and
socio-economic factors in relation to specified ecosystem management goals (Levin et al.
2008, 2009). Initial steps in the IEA process include the assessment of baseline
conditions defining the status of the system as well as the assessment of stressor impacts
and their links to source drivers and pressures. Results of the present study will be
available to support such initial steps in the development of any future LEA for the
Northeast U.S. Continental Shelf LME. While the focus of the present study is on
indicators of ecological condition, some human-dimension indicators have been included
as well (e.g., fish contaminant levels relative to human-health guidelines, water clarity,
marine debris, foul odors, oil slicks), which can be used to help address common public
concerns such as "Are the fish safe to eat?" or "Is the water clean enough to swim in?"
Humans are considered as both sources and receptors of ecosystem impacts in the IEA
and EAM process.
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2.0 Methods
2.1 Sampling Design and Field Collections
The sampling frame for this study was based on a generalized random-tessellation
stratified (GRTS) design. The GRTS design represents a unified strategy for selecting
spatially balanced probability samples of natural resources, in which sampling sites are
more or less evenly dispersed over the extent of the resource (Stevens & Olsen 2004).
Sampling was conducted from May 13 - 21, 2006 at 49 stations located throughout
coastal shelf waters of the MAB region, from Cape Cod to Cape Hatteras and within
approximately 1 nautical mile (NM) of shore seaward to the 100-m isobath (Figure 1,
Appendix A). The study is one of a series of assessments being conducted in coastal-
ocean waters of the U.S., using consistent methods and indicators to support national
comparisons.
Vertical water-column profiles of conductivity/salinity, temperature, depth, dissolved
oxygen, and pH were conducted at each station using a Sea-Bird Electronics (SEE)
Conductivity-Temperature-Depth (CTD) profiler, equipped with supplemental dissolved
oxygen and pH sensors. The CTD was an SEE 9Plus with an 1 IPlus deck unit that
provided real-time data recording of the vertical profile. The CTD was incorporated into
a frame that included a rosette of 12 Nisken bottles used to collect water samples at
discrete depths (near-surface, mid-depth, and near-bottom). Water samples were
analyzed for nutrients, total suspended solids (TSS), and chlorophyll a.
The CTD was lowered into the water until completely submerged and held just beneath
the surface for three minutes while the water pump was allowed to purge any air from the
system. The unit was then lowered to within one meter of the bottom at a rate of
approximately 1 m s"1. Four Nisken bottles were fired at approximately 1 m below the
surface, four at mid-depth, and the remaining four at near-bottom (approximately 1 m off
the bottom).
r\
Sediment samples were collected using a 0.04-m Young-modified Van Veen grab
sampler. Two replicate grab samples were retained for analysis of benthic infaunal
composition, sieved onboard through a 0.5-mm screen, and preserved in 10% buffered
formalin with rose bengal stain. The upper 2 - 3 cm of sediment from additional grabs
(typically 1 or 2) was combined to yield a sediment composite, which was then
homogenized and sub-sampled for analysis of metals, organic contaminants (pesticides,
PCBs, PAHs), grain size (% silt-clay), and total organic carbon (TOC). Sediment
samples (other than infauna) were kept frozen onboard the ship and later transferred to
the respective analytical laboratories for analysis.
Hook-and-line fishing was attempted at all 49 stations. Targeted species included
members of the families Bothidae (flatfish), Serranidae (seabass), Sparidae (scup), and
Gadiformes (hake). Unfortunately, none of the targeted species were collected during the
May 2006 sampling effort. However, through collaboration with the NOAA Fisheries
Service/Northeast Fisheries Science Center (NFS/NEFSC) winter 2007 bottom-trawl
-------
survey (NFS/NEFSC 2007), specimens of summer flounder (Paralichthys dentatus) were
obtained from 30 of their stations in overlapping portions of the study area (Fig IB).
Edible tissue (fillets) from these specimens was analyzed for metals, pesticides, PAHs,
PCBs, and PBDEs. While these fish were not collected during the May 2006 survey,
they should help to provide an indication of the levels of contaminants in edible fish
tissues likely to be encountered in the MAB region.
-------
70°W
-40°N
•38°N
36"N
4CFN
•38°N
36°N
74°W
72°W
70°W
Figure 1. A. Map of study area and station locations. B. Map showing location of 2007
NFS/NEFSC trawl locations used for fish tissue contaminant analysis.
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2.2 Water Quality Analysis
Readings of temperature, conductivity/salinity, dissolved oxygen, depth, and pH were
recorded directly from the CTD unit during its descent and ascent through the water
column. An index of density stratification (Aot) was calculated as the difference between
the computed bottom and surface density (ot) values, where ot is the density of a parcel of
water with a given salinity and temperature relative to atmospheric pressure (Fofonoff
and Millard 1983). Dissolved inorganic nutrients, including nitrate (NCV), nitrite
orthophosphate (HPO42"), silicate (HSiCV), and ammonium (NH4+); chlorophyll a; and
total suspended solids (TSS) were sampled at discrete water depths (near surface, mid-
water, and near-bottom) and analyzed following standard methods (U.S. EPA 1997; U.S.
EPA 1995). Only surface and bottom values for these various indicators are presented in
this report. Data for all depths are included in the study database and are available on
request to the authors.
2.3 Sediment TOC and Grain Size Analysis
Samples for grain size analysis were homogenized and diluted to a suspended slurry with
the aid of a chemical dispersant and the suspension was passed through a 63|im sieve.
The fine fraction passing through the sieve (< 63|im) and the coarse fraction retained on
the sieve (> 63|im) were separately dried and weighed (see U.S. EPA 1995). Total
organic carbon (TOC) was determined by combusting pre-acidified samples at high
temperature and measuring the volume of carbon dioxide gas produced (U.S. EPA 1995).
2.4 Sediment Contaminant Analysis
Sediments were analyzed for a suite of metals and organic pollutants using analytical
methods from the NOAA NS&T Program (Lauenstein and Cantillo 1993) or described in
the EMAP Laboratory Methods Manual (U.S. EPA 1995). Quality assurance/quality
control principles followed those outlined for the EMAP/NCA (U.S. EPA 2001b).
Sediment samples were extracted and analyzed for the presence of most metals (Ag, Al,
As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Se, Sn, Zn) using hydrofluoric acid digestion and
inductively-coupled plasma mass spectrometry (ICP-MS) using EPA method 6020A
(U.S. EPA 2006). Analysis of sediment samples for Hg was conducted using cold vapor
atomic absorption spectrometry (CVAA) consistent with EPA method 7471 A (U.S. EPA
2006).
Samples for analysis of semi-volatile organic compounds (PAHs) were extracted using
EPA method 3550B (U.S. EPA 2006) and analyzed by gas chromatography/mass
spectrometry (GC/MS) using a modified low-level method 8270C (U.S. EPA 2006).
Samples were extracted and analyzed for pesticides following EPA method 8081 A (U.S.
EPA 2006). The sample extracts underwent florisil cleanup. Sample extraction and
analysis for PCBs used EPA method 8082A (U.S. EPA 2006). The sample extracts
underwent sulfur and acid cleanup procedures.
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2.5 Fish Tissue Analysis
Fish tissues were analyzed for a suite of metals and organic contaminants using methods
previously described by Cooksey et al. (2008). Fish fillets were homogenized using a
ProScientific homogenizer in SOOmL Teflon containers. The well-homogenized samples
were split into separate aliquots for inorganic and organic contaminant analysis.
Tissue samples for all inorganic analytes except silver and mercury were analyzed using
nitric acid digestion and inductively-coupled plasma mass spectrometry (ICP-MS).
Silver was analyzed using Graphite Furnace Atomic Absorption (GFAA). Analysis of
tissues for mercury was conducted using a Milestone DMA-80 Direct Mercury Analyzer.
Aliquots of tissue homogenates for organic contaminant analysis were mixed with
anhydrous sodium sulfate to form a dry powder and then extracted in methylene chloride
using Accelerated Solvent Extraction (ASE). Following extraction, the residual water
was removed by passing the extract through phase separation paper containing a small
amount of sodium sulfate. After drying, the extracted sample was concentrated to 1000
jiL on an automatic concentrator (TurboVap). Lipid and other high molecular weight
components were then removed by size exclusion chromatography (SEC). Following
SEC, the volume was reduced to about 1000 jiL and the extract was split into two equal
aliquots (-500 jiL each) for subsequent cleanup and analysis.
Following cleanup using silica solid-phase extraction columns, tissue sample extracts
were analyzed for PCBs, PBDEs, and DDTs using an Agilent 6890/5973N GC/MS
operating in the electron impact ionization (El) mode. Additional organochlorine
pesticides (eg. aldrin, dieldrin, heptachlor, mirex) were analyzed using similar
instrumentation in the negative chemical ionization (NCI) mode. Analysis for PAHs was
conducted using a Varian 4000 GC/MS. Spiked blank, reagent blank, and appropriate
standard reference materials were included with each set (18) of samples to ensure the
integrity of the analytical method.
2.6 Benthic Community Analysis
The status of benthic communities was assessed using standard measures of abundance
(density/m2), richness (number of taxa), and diversity (Shannon H'; Shannon 1948,
Hayek and Buzas 1997). H' was calculated using base-2 logarithms. Total faunal
abundance was used to rank dominant taxa. Taxa were grouped according to higher
taxonomic classifications to determine relative percentages (by abundance and number of
taxa) of major groups of organisms (i.e., polychaetes, crustaceans, molluscs,
echinoderms, other taxa). The full list of identified taxa was examined to evaluate the
incidence of non-indigenous species vs. native species or ones with indeterminate status
relative to invasiveness.
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2.7 Quality Assurance
2.7.1 Quality Assurance and Quality Control
The quality assurance/quality control (QA/QC) program followed during the Mid-
Atlantic Bight assessment is described in the "Environmental Monitoring and Assessment
Program (EMAP): National Coastal Assessment Quality Assurance Project Plan 2001-
2004" (U.S. EPA 2001b). A performance-based approach was employed, featuring the
following standard practices: 1) continuous laboratory evaluation through the use of
Certified Reference Materials (CRMs), Laboratory Control Materials (LCMs), or
Standard Reference Material (SRM); 2) laboratory spiked sample matrices; 3) laboratory
reagent blanks; 4) calibration standards; 5) analytical surrogates; and 6) laboratory and
field replicates. The objective of this performance-based approach was to assist the
laboratories in meeting desired Data Quality Objectives (DQOs) as defined in the EMAP
Quality Assurance Project Plan (U.S. EPA 2001b). The subsequent sections provide
details of the QA procedures followed by analytical laboratories conducting analyses in
this report.
2.7.2 Water Quality Analyses
Nutrient analyses were conducted by B&B Laboratories, College Station, Texas. The
QA/QC procedures included the analyses of a method blank, spike/recovery check
sample and every 10 to 15 samples. Method blanks were used to determine that sample
preparation and analyses are free of contaminants. The duplicate sample was used to
determine the precision of the analysis. Spike/recovery samples were used to verify
analytical accuracy. All blanks and spike/recovery samples were subject to the identical
preparation and analysis steps as samples. The QA criterion for duplicate samples was
30% relative percent difference (RPD), and 10% of the true value for spike recovery
check sample. All analyses conducted for this assessment successfully met QA/QC
criteria.
2.7.3 Sediment Contaminant Analyses
Analyses of marine sediment samples were performed by GPL Laboratories of Frederick,
MD and CRG Laboratories of Torrance, CA. Both laboratories have well-defined
QA/QC guidelines described in their respective Quality Assurance Program Plan
documents. The QA program plans met or exceeded EPA recommended guidelines with
quality control samples accounting for at least 20% of the total number of samples
analyzed. The Quality Assurance Manager ensured that facilities, equipment, personnel
methods, records, and Quality Control procedures were in conformance with Standard
Operating Procedures (SOPs) as well as with applicable EPA QC guidelines.
Laboratories applied the following QA/QC procedures during the analyses:
BATCH: Quality Assurance Program Documents defined a batch as a group of 20 or
fewer samples of similar matrix, processed together under the same conditions and with
-------
the same reagents. Quality control samples were associated with each batch and were
used to assess the validity of the sample analyses. Batch sizes of 10-15 samples were
typically used.
PROCEDURAL BLANKS: Laboratory contamination was controlled through the
analysis of procedural blanks on a minimum frequency of 1 per batch. Quality Assurance
Program Plan documents required that all procedural blanks be below 10 times the MDL
and all detectable constituents in the blanks be flagged in the sample results.
ACCURACY: Accuracy of the project data was indicated by analysis of matrix spikes,
surrogate spikes, certified reference materials, and/or laboratory control materials on a
minimum frequency of 1 per batch. Quality Assurance Program Plan documents required
that 95% of the target compounds greater than 10 times the MDL be within the specified
acceptance limits. The requirements for PAHs, PCBs, and pesticides are that the "Lab's
value should be within ± 30% of true value on average for all analytes, not to exceed ±
35% of true value for more than 30% of individual analytes" (U.S. EPA 2001b). For
metals and other inorganic compounds, the laboratory's value for each analyte should be
within ± 20% of the true value of the CRM, LCM, or SRM.
PRECISION: Precision of the project data was determined by analysis of duplicate
matrix spikes, blank spikes, and/or duplicate test sample analysis on a minimum
frequency of 1 per batch. Quality Assurance Program Plan documents required that for
95% of the compounds > 10 times the MDL, the Relative Percent Difference (RPD)
should be within the specified acceptance range: RPD or CV should be <30%. The RPD
for the duplicate test sample analysis can be affected significantly by the homogeneity of
the sample matrix within the sample container itself, causing additional variability in the
analytical results. In these cases, the QA/QC Acceptance Limits may be exceeded.
In all cases of QA reports for batches, procedural blanks and certified reference materials
passed the stated accuracy and reproducibility criteria. However, failures of two types
were commonly reported: 1) The Relative Percent Difference (RPD) of unspiked
duplicate samples was out of control because the concentrations of PAHs, PCBs, or
pesticides in the sample were too small for reliable analysis (less than 10 times the MDL,
which is comparable to the Reporting Limit commonly used to evaluate precision in
samples with complex matrix effects); 2) Often for Al and Fe, spike recovery and RPD
control limits did not apply because the concentration in the sample exceeded the spike
concentration (i.e., the metals were not truly trace elements). The Quality Control
Manager determined that neither of these failures affected the goals of the program and
the batch data were accepted.
2.7.4 Benthic Taxonomy
Identification and enumeration of benthic fauna was performed by Barry A. Vittor &
Associates, Inc., Mobile, Alabama. Only skilled taxonomists conducted organism
identification. A minimum of 10% of samples were rechecked by other qualified
taxonomists for accuracy in identification and enumeration. Species lists from different
-------
labs were cross-checked, with external experts consulted for difficult identifications.
Judged accuracy rates were well above standard levels for sorting and taxonomy (quality
control reworks all > 95 %).
2.7.5 Tissue Contaminant Analyses
QA/QC procedures for tissue contaminant analyses were similar to those described above
for sediment contaminants. Spiked blank, reagent blank, and appropriate standard
reference materials were included with each set of samples to ensure the integrity of the
analytical method.
2.8 Data Analysis
The probabilistic sampling design used in this study allows calculation of estimates of the
percent area of the resource that corresponds to specified values of a given parameter
under consideration. Estimated cumulative distribution functions (CDFs), point
estimates, and 95% confidence intervals were developed for water quality, sediment, and
biological parameters measured in this study using formulas described in the EMAP
statistical methods manual (Diaz-Ramos 1996). Calculation of CDFs was facilitated
using algorithms (spsurvey package; Kincaid 2008) developed for R, a language and
environment for statistical computing and graphics (R Development Core Team 2008).
Measured parameters were compared to established thresholds of concern, where
available (Tables 1-3), and the corresponding percentiles of the estimated CDFs were
reported. Where no such recommended levels of concern exist (e.g., benthic metrics),
common distributional properties are reported (e.g., lower or upper percentiles).
Results of this study are compared, where appropriate, to results for estuaries from the
U.S. Environmental Protection Agency's National Coastal Assessment 2005-2006
database (NCA 2006). Many of the same parameters measured in the current study also
were measured as part of the NCA in estuaries of the Virginian Province, which includes
the coastal region of the northeast United States from Cape Cod, MA to the mouth of
Chesapeake Bay. The Virginian Province includes Chesapeake Bay which, in terms of
area, represents 62 % of the Province (NCA 2006). The Chesapeake Bay system also
experiences conditions which are distinctly different from other estuaries in the Province
(U.S. EPA 2008). Hence, some comparisons with the NCA 2005-2006 data are further
subdivided into Chesapeake Bay and non-Chesapeake Bay portions of the Province.
10
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Table 1. Thresholds used for classifying samples relative to various environmental indicators.
Indicator
Threshold
Reference
Water Quality
Salinity (psu)
Aot
DO (mg/L)
DIN/DIP
Sediment Quality
Silt-Clay Content (%;
TOC Content (mg/g)
Overall chemical
contamination of
sediments
Individual chemical
contaminant
concentrations in
sediments
< 5 = Oligohaline
5 - 18 = Mesohaline
>18 - 30 = Polyhaline
> 30 = Euhaline
> 2 = strong vertical stratification
< 2 = Low (Poor)
2 - 5 = Moderate (Fair)
> 5 = High (Good)
> 16 = phosphorus limited
< 16 = nitrogen limited
> 80 = Mud
20 - 80 = Muddy Sand
< 20 = Sand
> 50 = High (Poor)
20 - 50 = Moderate (Fair)
< 20 = Low (Good)
> 36 = High (Poor)
> 1 ERM value exceeded = High (Poor);
> 5 ERL values exceeded = Moderate (Fair);
No ERMs exceeded and < 5 ERLs exceeded = Low
(Good)
> ERM High probability of bioeffects
< ERL = Low probability of bioeffects
Carriker 1967
Nelson et al. 2008
USEPA 2008;
Diaz and Rosenberg
1995
Geider and La Roche
2002
USEPA 2008
USEPA 2008
Hyland et al. 2005
USEPA 2008
Longetal. 1995a; Table
2 herein
11
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Table 1 (continued).
Indicator Threshold Reference
Biological Condition
Reduced benthic < lower 10th percentile of all values for corresponding Nelson et al. 2008
taxonomic richness, variable
diversity, or abundance
Chemical Contaminants in > 1 chemical exceeded Human Health upper limit = USEPA 2008
Fish Tissues High (Poor)
> 1 chemical within Human Health risk range =
Moderate (Fair)
All chemicals below Human Health lower risk limit =
Low (Good)
Individual chemical Non-cancer (chronic systemic effects) endpoints USEPA 2000; Table 3
contaminants in fish based on consumption of four 8-ounce meals per herein
tissues month (general adult population).
Cancer risk endpoints (1 in 100,000 risk level) based
on consumption of four 8-ounce meals per month
(general adult population).
12
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Table 2. ERM and ERL guideline values in sediments (Long et al. 1995a).
Chemical
Metals (ng/g)
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Silver
Zinc
Organics (ng/g)
Acenaphthene
Acenaphthylene
Anthracene
Fluorene
2-Methylnaphthalene
Naphthalene
Phenanthrene
Benzo[a]anthracene
Benzo[a]pyrene
Chrysene
Dibenz [a,h] Anthracene
Fluoranthene
Pyrene
Low molecular weight PAHs
High molecular weight PAHS
Total PAHs
4,4-DDE
Total DDT
Total PCBs
ERL
8.2
1.2
81
34
46.7
0.15
20.9
1
150
16
44
85.3
19
70
160
240
261
430
384
63.4
600
665
552
1700
4020
2.2
1.58
22.7
ERM
70
9.6
370
270
218
0.71
51.6
3.7
410
500
640
1100
540
670
2100
1500
1600
1600
2800
260
5100
2600
3160
9600
44800
27
46.1
180
13
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Table 3. Risk-based EPA advisory guidelines for recreational fishers (USEPA 2000a).
EPA Advisory Guidelines
Concentration Range3
Metals (ug/g)
Arsenic (inorganic)b
Cadmium
Mercury (methylmercury)0
Selenium
Organics (ng/g)
Chlordane
DDT (total)
Dieldrin
Endosulfan
Endrin
Heptachlor epoxide
Hexachlorobenzene
Lindane
Mirex
Toxaphene
PAHs (benzo[a]pyrene)
PCB (total)
0.35-
0.35-
0.12-
5.9-
590-
59-
59-
7000-
350-
15-
940-
350-
230-
290-
1.6-
23-
0.70
0.70
0.23
12.0
1200
120
120
14000
700
31
1900
700
470
590
3.2
47
Health
Endpoint
non-cancer
non-cancer
non-cancer
non-cancer
non-cancer
non-cancer
non-cancer
non-cancer
non-cancer
non-cancer
non-cancer
non-cancer
non-cancer
non-cancer
cancerd
non-cancer
a Range of concentrations associated with non-cancer and cancer health endpoint risk for consumption of four 8-oz
meals per month.
b Inorganic arsenic, the form considered toxic, estimated as 2% of total arsenic.
0 Because most mercury present in fish and shellfish tissue is present primarily as methylmercury and because of the
relatively high cost of analyzing for methylmercury, the conservative assumption was made that all mercury is
present as methylmercury (U.S. EPA, 2000a).
d A non-cancer concentration range for PAHs does not exist.
3.0 Results and Discussion
Not all of the originally targeted 50 stations could be sampled for all parameters. Two
stations (16 and 46) off of Cape Cod were located in waters that were hazardous to
navigation, and were replaced with alternate stations 90 and 98, respectively. Station 98
was over rocky, hard-bottom habitat and only water samples were collected at the site.
The last station to be sampled during the survey cruise was station 30, but due to vessel
problems which used up the remaining cruise time, this station could not be sampled. In
all, sediment samples were collected at 48 of the original 50 sites; water quality samples
were collected at 49 sites.
3.1 Depth and Water Quality
3.1.1 Depth
Bottom depths for the 49 stations sampled in coastal shelf waters of the MAB ranged
from 13.6 m to 98.3 m (Table 4, Figure 2). The shallowest sites were located in near-
coastal waters off of Delaware and New Jersey (stations 27, 43, 47, and 49), while the
deepest sites were seaward of Nantucket Shoals near the 100 m depth contour. The mean
depth of all sites sampled was 45 m.
14
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Table 4. Summary of depth and water-column characteristics for near-bottom (lower 3 m) and near-surface (0.5 -4m) waters.
Near-bottom water
Depth (m)
Aot
Temperature (°C)
Salinity (psu)
DO (mg/L)
pH
DIN (mg/L)
DIP (mg/L)
DIN/DIP
Chi a (ng/L)
TSS (mg/L)
Mean
44.9
0.66
10.2
32.8
9.1
8.3
0.13
0.05
3.83
0.30
6.9
Range
13.6
0.00
6.5
30.0
8.4
8.0
0.01
0.02
0.68
0.01
1.1
-98.3
-1.81
-13.9
-35.0
-9.9
-8.6
-0.54
-0.12
- 10.88
-3.02
-36.4
CDF
10th pctl
18.9
0.06
7.3
31.5
8.5
8.1
0.02
0.03
0.84
0.02
2.0
CDF
50th pctl
40.3
0.65
10.0
32.5
9.0
8.3
0.04
0.05
2.26
0.08
5.6
CDF
90th pctl
75.2
1.21
13.5
34.4
9.7
8.6
0.29
0.08
8.50
0.77
12.0
Mean
—
—
11.6
32.2
8.9
8.4
0.04
0.04
1.91
0.23
5.6
Near-surface water
Range
7.8-
30.0-
7.7-
8.1-
0.01-
0.02-
0.43-
0.01-
0.9-
17.9
35.3
9.7
8.6
0.20
0.06
6.25
3.30
13.5
CDF
10th pctl
—
—
9.3
31.1
8.4
8.1
0.01
0.03
0.80
0.02
2.2
CDF
50th pctl
—
—
11.1
32.2
8.9
8.4
0.03
0.04
1.52
0.09
4.9
CDF
90th pctl
—
—
14.4
33.0
9.3
8.6
0.06
0.05
3.55
0.57
10.1
15
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3.1.2 General Water Characteristics: Temperature, Salinity, Water-Column
Stratification, DO, pH, TSS
Temperatures of surface water (0.5 to 4 m) ranged from 7.8 °C to 17.9 °C (Table 4). Fifty
percent of the area sampled had surface temperatures < 11.1 °C, and only 10 % of the
area had temperatures greater than 14.4 °C (CDF 90th percentile, Table 4). Bottom-water
temperatures (lower 3 m of the water column) were slightly cooler, ranging from 6.5 °C
to 13.9 °C, with 50 % of the area being < 10 °C and 10 % exceeding 13.5 °C. The coldest
bottom-water temperatures were observed in association with the "cold pool", an area of
cold, low-salinity water supplied by the Gulf of Maine and Georges Bank (Beardsley et
al. 1976). The "cold pool" occupies a region of the middle shelf along the southern flank
of Georges Bank and Nantucket Shoals, flowing westward and then south, roughly
parallel to the shoreline. It is bounded by an area of warmer, more saline slope water
along the shelf break.
Surface salinities varied between 30 psu and 35.3 psu. The mean and 50* percentile
(based on area) were 32.2 psu, with 10 % of the area having surface salinities between 33
psu and 35.3 psu. The majority of sites (representing approximately 80 % of the area)
had surface salinities between 31 and 33 psu. Bottom salinities varied between 30 and 35
psu, with fewer sites (representing about 65 % of the area) having bottom salinities
between 31 and 33 psu. A greater number of sites (about 31 % area) had salinities > 33
psu in near-bottom waters compared to the surface (10 % area). Ten percent of the study
area had bottom salinities > 34.4 psu, compared to only 4.1 % of area for surface waters.
Little evidence of density stratification was observed among the stations sampled in this
study. Computed values of Aot indicate that coastal shelf waters of the MAB at the time
of this sampling were well-mixed, with 83.7 % of the survey area having values of |Aot| <
1. Values of Aot ranged from 0 to 1.81, which are below the range considered to be
indicative of strong vertical stratification (Aot > 2; Nelson et al. 2008).
Consistent with the previous observations that the coastal shelf waters of the MAB were
well-mixed vertically, DO levels indicated that the waters also were well-oxygenated.
Measured DO concentrations occupied a fairly narrow range for both surface and bottom
waters, with surface DO concentrations ranging between 7.7 mg/L and 9.7 mg/L and
bottom water concentrations between 8.4 mg/L and 9.9 mg/L. None of these waters had
DO at low levels (< 2 mg/L) potentially harmful to benthic fauna and fish (Table 4,
Figure 2). DO levels in coastal shelf waters were relatively uniform compared to
estuarine waters of the mid-Atlantic region, which have been shown to be highly
variable, ranging from 0.4 - 12.7 mg/L in estuarine surface waters and 0.2 - 11.4 mg/L in
bottom waters (NCA 2006).
Due to technical problems with the CTD, pH was measured at less than half (n = 23) of
the 49 stations sampled during this survey. At the stations where pH was measured, the
range of values was 8.1- 8.6 for surface waters, and 8.0 - 8.6 for bottom waters, which
falls approximately within the normal range for seawater of 7.5 - 8.5 (Pinet 2006).
16
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Total suspended solids (TSS) ranged between 0.9 mg/L to 13.5 mg/L in surface waters.
Fifty percent of the area had TSS values < 4.9 mg/L, and 90 % of the area had surface
TSS values < 10.1 mg/L. With few exceptions, TSS concentrations in bottom waters
were similar to those of surface waters. The area-weighted 50* and 90* percentiles were
5.6 mg/L and 12.0 mg/L, respectively. One station at the entrance to Delaware Bay
(station 47) had a bottom-water TSS concentration of 36.4 mg/L. All other stations had
TSS concentrations < 16.3 mg/L. In comparison, suspended solids in estuaries were
considerably higher than offshore, and more variable. TSS values for surface waters in
estuaries ranged from 0.1 - 240 mg/L (mean of 17.2 mg/L) and bottom-water TSS
averaged 20.9 and ranged from 0.1-314 mg/L (NCA 2006).
The full range of values across all stations, summarized above, is depicted as CDF plots
in Figs. 2 and 3. The mean values by station (average of multiple CTD measurements for
near-surface and near-bottom waters for each station) appear in Appendices B and C.
17
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T(°C): Surface
20
100 -
3 80 ~
g40 -
5 20-
0 -
I I I I
30 31 32 33 34
Salinity (psu): Bottom
35
30 31 32 33 34
Salinity (psu): Surface
35
100 -
|8Q-
I60-
g40 -
^ 20 -
0 -I
!
7.5 8.0 8.5 9.0 9.5
DO (mg/L): Bottom
10.0
100 -
3 80 -
s«-
= 40 -
J 20 -
0 -
7.5 8.0 8.5 9.0 9.5
DO (mg/L): Surface
10.0
100 -
« 80 -
< 60 -
(ft
g 40 -
<3 20 -
0 -
: i : i : i
8.0 8.1 8.2 8.3 8.4 8.5 8.6
pH: Bottom
100 -
S80-
<60-
*
g 40 -
<3 20 -
0 -
I I : i i
8.0 8.1 8.2 8.3 8.4 8.5 8.6
pH (mg/L): Surface
Figure 2. Percent area (and 95% confidence intervals) of MAB shelf waters vs. selected water-
quality characteristics.
18
-------
100 -
g
60 -
!
: 40 -
j
0 -
: ! : : i :
0.0 0.1 0.2 0.3 0.4 0.5 0.6
DIN (mg/L): Bottom
100 -
| 80 -
| 40 -
y 20 -
0 -
0.05 0.10 0.15
DIN (mg/L): Surface
0.20
100 -
g 40 -
0 -I
100 -
i i i i
0.02 0.04 0.06 0.08 0.10 0.12
DIP (mg/L): Bottom
0.02 0.03 0.04 0.05
DIP (mg/L): Surface
0.06
100 -
3 80 ~
g40 -
5 20-
0 -
I I
4 6
DIN/DIP: Bottom
I
10
100 -
a 80 -
I60'
S 40 -
^ 20 -
0 -I
I I
12345
DIN/DIP: Surface
100 -
3 80 -
g40 -
^20 -
0 -J
!
0.0 0.5 1.0 1.5 2.0 2.5
Chi <; (Ug/L): Bottom
3.0
100 -
a 80 -
< 60 -
g 40 -
^20-
0 -
; . ! I '
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Chi a (Ug/L): Surface
100 -
« 80 -
I60'
g 40 -
0 -
10 15 20 25 30 35
TSS (mg/L): Bottom
100 -
« 80 -
g 40 -
a
'J 20 -
0 -
Figure 3. Percent area (and 95% confidence intervals) of MAB shelf waters vs. nutrient,
chlorophyll, and TSS concentrations.
4 6 8 10 12 14
TSS (mg/L): Surface
19
-------
3.1.3 Nutrients and Chlorophyll
The concentration of dissolved inorganic nitrogen (DIN: nitrogen as nitrate + nitrite +
ammonium) in surface waters ranged from 0.01 mg/L to 0.20 mg/L and averaged 0.04
mg/L (Table 4, Figure 3). Ninety percent of the study area surface waters had DIN
concentrations < 0.06 mg/L. Bottom water concentrations of DIN tended to be higher
than surface concentrations. For example, only about 50% of bottom waters had DIN <
0.06 mg/L and the average concentration was 0.13 mg/L (range of 0.01 - 0.54 mg/L).
While there are no published water-quality guidelines for DIN in offshore waters, Figure
4 shows the spatial distribution of DIN in bottom waters relative to evaluation cutpoints
established for neighboring estuaries (USEPA 2008). The figure depicts a clear pattern
of higher bottom-water DIN levels along the outer shelf in comparison to inner-shelf
sites. This observation is consistent with other published descriptions of the MAB, which
have found nutrient levels to be higher in bottom waters than in surface waters,
particularly along the outer shelf. Matte and Waldhauer (1984) found that concentrations
of nutrients, particularly nitrate, in bottom waters of the shelf exhibit a general increase
seaward and tend to remain high year-round. They suggest that slope waters rich in
nutrients represent a reservoir of nitrogen that can replace nitrogen utilized from inshore
waters. In comparison to these offshore waters, estuaries of the region tend to have
higher levels of DIN, with values ranging from 0.01 - 3.0 mg/L in surface waters and
averaging 0.17 mg/L (NCA 2006, results not shown). Similarly, bottom-water
concentrations of DIN in estuaries ranged from 0.01 - 2.2 mg/L and averaged 0.15 mg/L.
Concentrations of dissolved inorganic phosphorus (DIP) in surface waters ranged
between 0.02 mg/L and 0.06 mg/L and averaged 0.04 mg/L (Table 4). Ninety percent of
the study area surface waters had DIP concentrations < 0.05 mg/L. Bottom-water
concentrations of DIP were slightly higher than those measured in surface waters,
ranging from 0.02 mg/L to 0.12 mg/L and averaging 0.05 mg/L (Table 4). A much
smaller portion of the study area (about 50 %) had bottom-water concentrations of DIP <
0.05 mg/L. These DIP concentrations in bottom waters of the MAB coastal shelf are
higher than those observed in estuaries of the region (e.g., 82 % of estuarine area with <
0.05 mg/L of DIP; NCA 2006). While levels of DIP above 0.05 mg/L are considered
high for estuaries and an indication of poor water quality (USEPA 2008), a similar
interpretation may be inappropriate for offshore waters. There are no published water-
quality guidelines for DIP in offshore waters, thus DIP > 0.05 mg/L in 50% of the study
area is not necessarily an indication of abnormally high phosphate levels and
deteriorating water quality.
Other studies of nutrient and chlorophyll distributions in offshore waters of the MAB
region have found levels similar to those presented here. In their description of
chlorophyll enhancement at the shelf break of the MAB, Ryan et al. (1999) noted that
upwelling or vertical mixing to near-surface waters was required for the chlorophyll
enhancement that they detected by remote sensing, since their study (May/June) occurred
after the period of nutrient depletion and onset of stratified conditions that follow the
well-mixed and nutrient-rich winter water-column conditions. Matte and Waldhauer
(1984) reported that upwelling can be expected to occur during periods of southwesterly
20
-------
winds; the mean wind direction for the period of May 13-21, 2006 (this study) was 207
degrees (calculated from NOAA National Buoy Data Center data). Cross-frontal mixing
events between slope and shelf waters also are important in nutrient fluxes in the MAB
(Townsend et al. 2005). Hence, nutrient levels observed during the present study appear
to be comparable to results from other studies in the MAB region.
The ratio of DIN to DIP was calculated as an index of nutrient limitation. A DIN:DIP
ratio > 16 is considered to be indicative of phosphorus limitation, while values of
DIN:DIP < 16 suggest that nitrogen is the limiting factor for primary production (Geider
and La Roche 2002). DIN:DIP ratios (Table 4) ranged from 0.43 to 6.25 (mean of 1.91)
in surface waters, and from 0.68 to 10.88 (mean of 3.83) in bottom waters, which are
strongly indicative of nitrogen limitation. In comparison, estuaries of the region tend to
be less nitrogen-limited, or in some cases phosphorus-limited, with DIN:DIP ratios
ranging from 0.12 - 24.1 (mean of 4.5) in bottom waters and from 0.01 - 112 (mean of
7.0) in surface waters (NCA 2006).
Surface-water concentrations of chlorophyll a, an indicator of phytoplankton biomass and
abundance, ranged from 0.01 jig/L to 3.30 jig/L and averaged 0.23 jig/L (Table 4).
Bottom-water concentrations of chlorophyll a were similar to concentrations in surface
waters, ranging between 0.01 |ig/L and 3.02 |ig/L and averaging 0.3 |ig/L. These levels
tended to be lower than those observed in estuaries of the region, with surface-water
concentrations in estuaries ranging from 0.1 - 302 |ig/L (mean of 11.8 |ig/L) and bottom-
water concentrations ranging from 0.1 - 87.2 |ig/L and averaging 5.9 |ig/L.
21
-------
?65W
72° W
70"W
40°N-
Dissolved Inorganic Nitrogen (DIN)
• <0.1 mg/L (Low)
0.1 - 0.5 mg/L (Moderate)
• >0.5 mg/L (High)
74°W 72°W 70°W
Figure 4. Map of study area showing distribution of DIN in bottom water.
3.2 Sediment Quality
3.2.1 Grain Size and TOC
The majority of the survey area (92 % area) consisted of bottom sediments composed of
sands (< 20 % silt-clay content). Three sites had sediments composed of intermediate
muddy sands (20 - 80 % silt-clay), and only one site had sediments classified as muds (>
80 % silt-clay). This is consistent with other studies (e.g., Rabalais and Boesch 1987)
that have found shelf surface sediments to be composed of sands (> 75 % and mostly >
90 %) or gravelly sands to water depths of at least 200 m. Results from the present study
are summarized in Table 5 and Figure 5.
TOC content of sediments was low, ranging from 0.27 - 16.04 mg/g and averaging 1.92
mg/g throughout the region (Table 5). Most of the study area (92 %) had sediment TOC
concentrations < 5 mg/g and all sites (100% of the area) had concentrations < 20 mg/g,
below levels associated with a moderate to high incidence of effects on benthic fauna
(Figure 6).
22
-------
Table 5. Summary of sediment characteristics.
Parameter
Mean
Range
CDF
10th pctl
CDF
50%ctl
CDF
90th pctl
TOC (mg/g)
% silt-clay
Mean ERM-Q
1.92
6.6
0.007
0.27-16.04
0.2-86.9
0.001-0.031
0.33
0.3
0.001
0.72
0.9
0.005
4.77
19.3
0.011
A.
B.
100
I 80
?«H
>
! 40-
0
0
80
% Area with Silt-Clay:
D < 20% (Sand)
D 20-80% (Muddy Sand)
• >80%(Mud)
20 40 60
% Silt-Clay
Figure 5. (A) Percent area (and 95% CI) represented by varying levels of the % silt-clay content
of sediment, and (B) percent area having silt-clay content within specified ranges.
A.
B.
100
80
« 60
>
J 40
|20
0
TOC (mg/g)
• > 50 (High)
D 20-50 (Moderate)
D < 20 (Low)
0
15
5 10
TOC (mg/g)
Figure 6. (A) Percent area (and 95% CI) represented by varying levels of TOC content of
sediment (mg/g), and (B) percent area having TOC content within specified ranges.
3.2.2 Chemical Contaminants in Sediments
23
-------
The biological significance of chemical contamination of sediments was evaluated by
comparing measured contaminant concentrations to sediment quality guidelines (SQGs)
developed by Long et al. (1995a). Effects-Range Low (ERL) values represent lower
bioeffect limits, below which adverse effects of contaminants on sediment-dwelling
organisms are not likely to occur (the ERL corresponds to an expected incidence of
toxicity of about 10%). Effects-Range Median (ERM) values are mid-range
concentrations above which adverse biological effects are more likely to occur (the ERM
is the concentration corresponding to an expected incidence of toxicity of about 50%).
Any site having one or more chemicals in excess of their corresponding ERM values (see
Table 2) was rated as having poor sediment quality; any site with five or more chemicals
between the corresponding ERL and ERM values was rated as fair; any site with no
ERMs exceeded and < 5 ERLs exceeded was rated as having good sediment quality
(sensu U.S. EPA 2008). Overall sediment contamination from multiple chemicals also
was expressed through the use of mean ERM quotients (sensu Long et al. 1998; Hyland
et al. 1999, 2003). The mean ERM quotient (mean ERM-Q) is the mean of the ratios of
individual chemical concentrations in a sample relative to corresponding published ERM
values (using all chemicals in Table 2 except nickel, low- and high-molecular-weight
PAHs, and total PAHs). A useful feature of this method is that overall contamination in a
sample from mixtures of multiple chemicals present at varying concentrations can be
expressed as a single number that can be compared to values calculated the same way for
other samples (either from other locations or sampling occasions).
The overall mean, range, and area-weighted percentiles of mean ERM-Qs are shown in
Table 5. These values are nearly an order of magnitude lower than values calculated for
northeast estuaries (area-weighted 10th, 50th, and 90th percentiles of 0.01, 0.04, and 0.12,
respectively; NCA 2006), suggesting that concentrations of chemical contaminants in
shelf sediments of the MAB are at relatively low background levels. None of the stations
had mean ERM-Qs high enough to suggest significant risks of adverse effects on benthic
fauna. Hyland et al. (2003) reported the highest incidence of impaired benthic
assemblages (85% of samples) in mid-Atlantic (Virginian Province) estuaries at mean
ERM-Qs above a critical point of 0.473 and a low incidence of effects (9% of samples) at
mean ERM-Qs < 0.022. Although in the present study we are dealing with offshore
benthic fauna, none of the stations had mean ERM-Qs in this upper bioeffect range
(which are the most applicable data known to us for comparison). Except for one station
with a mean ERM-Q of 0.031 (Table 5), the majority of stations (97.9 % of the study
area) had values that were well within the reported low-risk range.
No contaminants were found in excess of their corresponding ERMs (Table 6). Only
three chemicals, arsenic, nickel, and total DDT, exceeded their corresponding ERL
guidelines. The ERL exceedances for arsenic occurred at three sites: Stations 12, 13, and
17 with concentrations of 8.2, 11, and 8.5 |ig/g, respectively. These three sites
represented only 6.3 % of the survey area. The overall range of concentrations for
arsenic (0-11 |ig/g dry mass) was within the range typical of uncontaminated near-shore
marine sediments (5-15 |ig/g dry weight total arsenic) reported by Neff (1997) and
reflects its natural presence at low to moderate concentrations in crustal rocks of the
region. Similarly, concentrations of nickel at one site (21 |ig/g dry mass, station 29),
24
-------
representing 2.1 % of the study area, barely exceeded the ERL guideline of 20.9 |ig/g.
Concentrations of total DDT (sum of 2,4'-DDD, 4,4'-DDD, 2,4'-DDE, 4,4'-DDE, 2,4'-
DDT, and 4,4'-DDT) were detectable in sediment samples at eight sites and exceeded the
ERL guideline of 1.58 ng/g at five sites (Figure 7), which represent 10 % of the study
area. Exceedances for total DDT were driven by 4,4'-DDT (four sites) and 2,4'-DDE
(one site). DDT and its metabolites have been detected in major estuaries of the region,
including Chesapeake Bay (Hartwell and Hameedi 2007), Delaware Bay (Hartwell et al.
2001), the Hudson-Raritan Estuary (Long et al. 1995b), and Long Island Sound (Wolfe et
al. 1994). While some of these contaminants have been able to make their way onto the
shelf, currently they appear to be present at low concentrations in the sediment. Total
DDT levels were below the limit of detection at all of the remaining 40 sites where
sediment samples were collected. Many of the other chemicals measured in this study
also were below method detection limits.
Compared to overall sediment contaminant concentrations in estuaries of the region, shelf
sediments have much lower levels (Figure 8). For example, contaminant levels measured
in sediments of the Virginian Province, analyzed as part of the U.S. EPA National
Coastal Assessment (NCA 2006), indicated that 5 % of estuarine sediments in the region
were in poor condition (> 1 ERM exceeded), 15 % were rated as fair (> 5 ERLs
exceeded), and 80 % were in good condition (no ERMs exceeded and fewer than 5 ERLs
exceeded). Similarly, using the above criteria, the third National Coastal Condition
Report (U.S. EPA 2008) concluded that 9 % of coastal and estuarine sediments in the
northeast region of the U.S., inclusive of the MAB states, were in poor condition with
respect to sediment contaminant concentrations and 12 % were fair. The remaining 79 %
of area was rated as good. In contrast, all of the sites sampled in this study (100 % of the
study area) were rated as good.
25
-------
Table 6. Summary of chemical contaminant concentrations in sediments ('N.D.' = not detected;'-' = no corresponding ERL or ERM available).
Concentration > ERL, < ERM
Analyte
Metals (% dry)
Aluminum
Iron
Trace Metals (ng/g dry mass)
Antimony
Arsenic
Cadmium
Chromium
Copper
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Tin
Zinc
PAHs (ng/g dry)
Acenaphthene
Acenaphthylene
Anthracene
Benz [a] anthracene
Benzo[a]pyrene
Benzo [b]fluoranthene
Benzo [g,h,i]perylene
Benzo [kjfluoranthene
Biphenyl
Chrysene
Dibenz[a,h]anthracene
Dibenzothiophene
Fluoranthene
Fluorene
Indeno [1,2,3 -c,d]pyrene
Naphthalene
1 -Methylnaphthalene
Mean (Std. Dev.)
1.374 (0.680)
0.936 (0.633)
0.138 (0.219)
3.479 (2.198)
0.130 (0.2)
12.921 (12.329)
1.719 (2.178)
9.348 (5.858)
214.760 (134.235)
0.006 (0.015)
4.285 (4.412)
0.128 (0.345)
0.031 (0.045)
3.558 (0.745)
19.148 (14.639)
N.D.
N.D.
N.D.
0.469 (1.895)
0.125 (0.866)
0.323 (1.586)
N.D.
N.D.
N.D.
0.677 (2.769)
N.D.
N.D.
1.552 (4.083)
N.D.
N.D.
N.D.
N.D.
Range
0.186-3.650
0.121-2.840
0-0.83
0.75-11
0-0.7
1-57
0 - 10.5
2.6-30.6
30.7-643
0-0.085
0.66-21
0-1.3
0-0.15
2.8-6.4
4.2-66.3
N.D.
N.D.
N.D.
0-10
0-6
0-9
N.D.
N.D.
N.D.
0-14
N.D.
N.D.
0-18
N.D.
N.D.
N.D.
N.D.
# Stations
-
-
-
3
0
0
0
0
-
0
1
-
0
-
0
0
0
0
0
0
-
-
-
-
0
0
-
0
0
-
0
-
% Area
-
-
-
6.3
0
0
0
0
-
0
2.1
-
0
-
0
0
0
0
0
0
-
-
-
-
0
0
-
0
0
-
0
-
Concentration > ERM
# Stations
-
-
-
0
0
0
0
0
-
0
0
-
0
-
0
0
0
0
0
0
-
-
-
-
0
0
-
0
0
-
0
-
% Area
-
-
-
0
0
0
0
0
-
0
0
-
0
-
0
0
0
0
0
0
-
-
-
-
0
0
-
0
0
-
0
-
26
-------
Table 6 (continued).
Concentration > ERL, < ERM
Analyte
2-Methylnaphthalene
2,6-Dimethylnaphthalene
2,3,5-Trimethylnaphthalene
Phenanthrene
1 -Methylphenanthrene
Pyrene
Low Molecular Weight PAHs
High Molecular Weight PAHs
Total PAHs3
PCBs (ng/g dry)
Total PCBsb
Pesticides (ng/g dry)
2,4'-DDD (o,p'-DDD)
2,4'-DDE (o,p'-DDE)
2,4'-DDT (o,p'-DDT)
4,4'-DDD (p,p'-DDD)
4,4'-DDE (p,p'-DDE)
4,4'-DDT (p,p'-DDT)
Aldrin
alpha-Chlordane
Dieldrin
Endosulfan I
Endosulfan II (beta-Endosulfan)
Endosulfan sulfate
Endrin
gamma-HCH (g-BHC, lindane)
Heptachlor
Heptachlor epoxide
Hexachlorobenzene (HCB)
Mirex
Total DDTsc
trans-Nonachlor
Mean (Std. Dev.)
N.D.
N.D.
N.D.
0.156 (1.083)
N.D.
0.604 (2.083)
0.156 (1.083)
3.750 (11.330)
3.906 (12.026)
0.714 (1.68)
N.D.
0.038 (0.26)
N.D.
0.009 (0.061)
0.023 (0.096)
0.270 (0.719)
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.013 (0.092)
N.D.
0.340 (0.836)
N.D.
Range
N.D.
N.D.
N.D.
0-7.5
N.D.
0-10
0-7.5
0-51
0-58.5
0 - 7.24
N.D.
0-1.8
N.D.
0 - 0.42
0-0.55
0-3.1
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0 - 0.64
N.D.
0-3.1
N.D.
# Stations
0
-
-
0
-
0
0
0
0
0
-
-
-
-
0
-
-
-
-
-
-
-
-
-
-
-
-
-
5
-
% Area
0
-
-
0
-
0
0
0
0
0
-
-
-
-
0
-
-
-
-
-
-
-
-
-
-
-
-
-
10.4
-
Concentration > ERM
# Stations
0
-
-
0
-
0
0
0
0
0
-
-
-
-
0
-
-
-
-
-
-
-
-
-
-
-
-
-
0
-
% Area
0
-
-
0
-
0
0
0
0
0
-
-
-
-
0
-
-
-
-
-
-
-
-
-
-
-
-
-
0
-
a Sum of 23 measured PAHs.
b Sum of 21 measured PCB congeners.
; Sum of 2,4'-DDD, 4,4'-DDD, 2,4'-DDE, 4,4'-DDE, 2,4'-DDT, and 4,4'-DDT.
27
-------
76°W
74°W
72°W
70°W
40°N-
Total DDT in Sediment
• Not detected
Detected, but below CRL
ERL exceeded
36°N-
'36°N
70°W
Figure 7. Map of study area showing distribution of total DDT in sediments. Red symbol:
concentration exceeded the ERL value of 1.58 ng/g but was below the ERM value of 46.1 ng/g
(from Long et al. 1995a).
28
-------
5 ±4.5%
(64)
A. MAB shelf sediments B. Virginian Province estuaries
(2006, this study) (NCA 2006)
D Good: No KRM exceeded and <5 KRLs exceeded
D Fair : > 5 KRLs exceeded
• Poor : > I KRM exceeded
Figure 8. Comparison of contamination in MAB shelf sediments (2006, this study) vs. estuaries
of the Virginian Province (NCA 2006).
3.3 Chemical Contaminants in Fish Tissues
Because none of the species offish targeted for chemical contaminant analysis were
collected on the core May 2006 survey, samples of summer flounder (Paralichthys
dentatus) were obtained from a subsequent winter bottom-trawl survey conducted
February 6 - March 2, 2007 by the NOAA Fisheries Service, Northeast Fisheries Science
Center (NFS/NEFSC) and used for this purpose. Fish samples were taken from 30
bottom-trawl locations in shelf waters between Sandy Hook, NJ and Cape Hatteras, NC
(Figure IB). Although these samples were not part of the core probabilistic sampling
design and thus should not be used for CDF calculations and spatial estimates of
condition, they provide a good indication of the range of chemical contaminant levels
likely to be encountered in edible tissues from bottom fish in the MAB study area.
Concentrations of a suite of metals, pesticides, and PCBs were measured in edible tissues
(fillets) of 30 individual summer flounder, one each from the 30 trawl sites, and
compared to risk-based EPA advisory guidelines for recreational fishers (Table 3). The
guidelines selected for this analysis were endpoints associated with an average
consumption rate of four 8-oz fish meals per month (from USEPA 2000a), which is
consistent with the comparison basis used currently in the National Coastal Condition
Report (USEPA 2008) and by States for setting fish advisories. A station was rated as
"good" if all chemical contaminants listed in Table 3 had concentrations below the
corresponding lower endpoints, "fair" if at least one contaminant fell within the
29
-------
corresponding lower and upper endpoints, and "poor" if at least one contaminant
occurred at a concentration above the upper endpoint (USEPA 2008).
None of the 30 stations where fish were measured had chemical contaminants in fish
tissues above the corresponding upper human-health endpoints (Table 7, Figure 9). Thus
none of these stations were rated as "poor" with respect to contaminant body burdens.
Three stations - NFS/NEFSC 14, 21, and 53 - had total PCB concentrations in tissues
(26.6, 42.4, and 38.6 ng/g respectively) that were between the corresponding lower and
upper endpoints and thus were rated as "fair." One of the above stations (21) and an
additional station (59) had total mercury concentrations (assumed to be all
methylmercury, sensu U.S. EPA 2000a) between the corresponding lower and upper
endpoints for methylmercury. All other stations had concentrations of contaminants
listed in Table 3 that were below corresponding lower endpoints and thus were rated as
"good."
As a side note, total PCBs and inorganic arsenic were both present in fish tissues at
slightly elevated levels, though below the (non-cancer) human-health risk endpoints,
consistently at 16 of the remaining 27 stations in the case of total PCBs and across all 30
stations in the case of inorganic arsenic. To be consistent with methods used in the
National Coastal Condition Report III (USEPA 2008), non-cancer human-health risk
endpoints were used in this report as the basis for comparisons with observed fish tissue
contaminant levels (with the exception of benzo(a)pyrene, for which only cancer risk
endpoints exist). However, USEPA (2000a) also provides risk-based cancer endpoints
for nine of the remaining 15 contaminants listed in Table 3. For example, based on an
average consumption of four 8-oz fish meals per month and an acceptable risk level of 1
in 100,000, the lower to upper cancer-risk endpoints would be 5.9 - 12.0 ng/g for total
PCBs and 0.0078 - 0.016 ng/g for inorganic arsenic (USEPA 2000a). Though below
even the lower non-cancer endpoint, inorganic arsenic concentrations exceeded both of
these cancer-risk endpoints at all 30 stations where fish were measured (data not reflected
in tables). Concentration of total PCBs exceeded its corresponding upper cancer
endpoint at eight stations and was between the lower and upper endpoints at an additional
11 stations.
30
-------
Table 7. Summary of contaminant concentrations (wet weight) measured in tissues of summer
flounder, P. dentatus. A total of 30 fish (one each from 30 stations) were analyzed. All measured
contaminants are included. Concentrations are compared to human-health guidelines where
available (from US EPA 2000a, also see Table 3 herein). (TSf.D.1 = Not detected; TSf.M.' = Not
measured;'-' = no corresponding guideline available).
Analyte
Mean
No. of fish exceeding
health endpoints
Metals (ng/g wet weight)
Aluminum
Antimony
Arsenic
Arsenic (Inorganic)3
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Methylmercury (estimated)13
Iron
Lead
Lithium
Manganese
Nickel
Selenium
Silver
Thallium
Tin
Uranium
Vanadium
Zinc
PAHs (ng/g wet weight)
Acenaphthene
Acenaphthylene
Anthracene
Benz [a] anthracene
Benzo[a]pyrene
Benzo [b]fluoranthene
Benzo [e]pyrene
Benzo [g,h,i]perylene
Benzo [j ,k]fluoranthene
Biphenyl
Chrysene+Triphenylene
Dibenz[a,h]anthracene
Dibenzothiophene
Flouranthene
Flourene
Indeno [1,2,3 -c,d]pyrene
Napthalene
1 -Methylnaphthalene
2-Methylnaphthalene
2,6-Dimethylnaphthalene
1.628
0.049
3.194
0.064
0.013
N.D.
0.001
0.293
0.000
0.211
0.075
8.101
0.094
0.010
0.174
0.003
0.653
N.D.
N.D.
0.000
N.D.
0.086
4.893
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
^-j _ —
0.000-4.330
0.000 - 0.092
0.942-7.890
0.019-0.158
0.000-0.032
N.D.
0.000-0.001
0.198-0.442
0.000-0.012
0.177-0.256
0.015-0.152
6.720 - 10.000
0.000-0.891
0.000-0.019
0.104-0.292
0.000 - 0.020
0.556-0.858
N.D.
N.D.
0.000 - 0.007
N.D.
0.030-0.139
3.500-7.000
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
> Lower
&
< Upper
-
-
-
0
-
-
0
-
-
-
2
-
-
-
-
-
0
-
-
-
-
-
-
-
-
-
-
0
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
> Upper
-
-
-
0
-
-
0
-
-
-
0
-
-
-
-
-
0
-
-
-
-
-
-
-
-
-
-
0
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
31
-------
Table 7 (continued).
Analyte
1 ,6,7-Trimethylnaphthalene
Perylene
Phenanthrene
1 -Methylphenanthrene
Pyrene
Total PAH
PBDEs (ng/g wet weight)
PBDE 100
PBDE 138
PBDE 153
PBDE 154
PBDE 17
PBDE 183
PBDE 190
PBDE 28
PBDE 47
PBDE 66
PBDE 71
PBDE 85
PBDE 99
PCBs (ng/g wet weight)
Total PCBsc
Pesticides (ng/g wet weight)
2,4' - ODD (o,p' - ODD)
2,4' - DDE (o,p' - DDE)
2,4' - DDT (o,p' - DDT)
4,4' - ODD (p,p' - ODD)
4,4' - DDE (p,p' - DDE)
4,4' - DDT (p,p' - DDT)
Aldrin
Chlorpyrifos
cis-Chlordane (alpha-
Chlordane)
Dieldrin
Endosulfan
Endosulfan I
Endosulfan II
Endosulfan sulfate
Endrin
Heptachlor
Heptachlor epoxide
Hexachlorobenzene
Lindane
Mirex
Total DDT
Total Chlordane
Toxaphene
trans-Nonachlor
Mean
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
1.033
N.D.
N.D.
N.D.
0.074
11.133
N.D.
0.021
0.251
0.209
1.925
N.D.
N.D.
N.D.
N.D.
0.034
N.D.
N.D.
N.D.
N.D.
N.M.
N.D.
N.D.
N.D.
N.D.
2.406
N.D.
N.D.
N.M.
N.D.
Range
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.000 - 5.320
N.D.
N.D.
N.D.
0.000-1.160
1.300-42.400
N.D.
0.000-0.348
0.000-2.136
0.000 - 1.461
0.000 - 5.974
N.D.
N.D.
N.D.
N.D.
0.000-0.271
N.D.
N.D.
N.D.
N.D.
N.M.
N.D.
N.D.
N.D.
N.D.
0.000 - 9.920
N.D.
N.D.
N.M.
N.D.
No. of fish exceeding
health endpoints
> Lower
&
< Upper
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
o
J
-
-
-
-
-
-
-
-
-
0
0
-
-
-
-
-
0
0
0
0
0
0
-
-
> Upper
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0
-
-
-
-
-
-
-
-
-
0
0
-
-
-
-
-
0
0
0
0
0
0
-
-
1 Estimated as 2% of the measured total arsenic.
5 Measured as total mercury and assumed to be all methylmercury.
: Sum of 79 measured PCB congeners.
32
-------
74°W
72°W
70°W
40°N-
38°N-
36°N-
Tolal PCBs in fish (issue
< 23 ng/g (Good)
o 23 - 47 ng/g (Fair)
• > 47 ng/g (Poor)
36°N
74C'W
72°W
70°W
Figure 9. Distribution of PCB concentrations in fish tissues (fillets) relative to EPA (2000a) non-
cancer human-health guidelines.
33
-------
3.4 Status of Benthic Communities
Macrobenthic infauna (those retained on a 0.5-mm sieve) were sampled at a total of 48
stations throughout the study region. Two grabs (0.04 m2 each) were collected at every
station except station 14, where a single grab was collected, resulting in a total of 95
grabs. Measures of taxonomic diversity and abundance were calculated separately for
each of the 95 grabs and averaged by station where indicated (e.g., mean # taxa/0.04 m2,
mean H70.04 m ). The resulting data here are used to assess the status of benthic
community characteristics (taxonomic composition, diversity, abundance, and dominant
taxa), the incidence of non-indigenous species, and potential linkages to ecosystem
stressors throughout the coastal shelf waters of the MAB from Cape Cod, MA to Cape
Hatteras, NC.
The status of benthic communities in shelf sediments of the MAB is also compared to
estuaries of the Virginian Province, sampled in 2005-2006 as part of the U.S. EPA
National Coastal Assessment (NCA 2006). The NCA benthic data represent 353 stations,
with a single 0.04-m grab sample collected at each site (with the exception of 20 sites in
Delaware Bay, which were sampled using a 0.1-m2 grab). Of the 353 NCA estuarine
benthic samples, 205 were analyzed by Barry Vittor & Associates, who also analyzed the
samples from the MAB (this study). Maryland estuarine benthic samples (n=48) were
analyzed for the NCA by Versar, Inc. Virginia NCA benthic samples (n=100) were
analyzed by the benthic ecology laboratory at Old Dominion University in Norfolk, VA.
While some differences in the level of taxonomic identification may exist among benthic
laboratories, all samples were processed in accordance with methods outlined in the
EMAP Laboratory Methods Manual (U.S. EPA 1995).
3.4.1 Taxonomic Composition
A total of 381 taxa were identified throughout the study area, of which 215 were
identified to the species level. Polychaetes were the dominant taxa (Figure 10, Table 8),
both by percent of taxa (43 %) and percent abundance (46 %). Crustaceans and molluscs
were the second and third dominant taxa, respectively, both by percent of taxa (31 %
crustaceans, 19 % mollusks) and percent abundance (36 % crustaceans, 10 % mollusks).
Collectively, these three groups represented 92 % of total taxa and 93 % of total faunal
abundance. Crustaceans were represented primarily by amphipods (66 identifiable taxa,
17.3 % of the total number of taxa), followed by cumaceans (19 taxa, 5 % of total taxa),
ostracods (15 taxa, 3.9 % of total taxa), and isopods (10 taxa, 2.6 % of total taxa; Table
8). Molluscs were represented mainly by bivalves (51 taxa, 13.4 % of total taxa),
followed by gastropods (19 taxa, 5 % of total taxa).
Macrobenthic composition also was examined in relation to bathymetric zones by
dividing the survey area into inner (-14 - 30 m), middle (30 - 50 m), and outer (50 - 100
m) shelf (sensu Boesch 1979). Numbers of taxa (as percent of total) for the major
taxonomic groups identified in Figure 10A remained fairly constant across inner, middle,
and outer shelf habitats. However, the relative abundance of major taxonomic groups
varied (Figure 10B), with the inner shelf dominated by polychaetes (53% versus 40% and
34
-------
44% for middle and outer shelf, respectively). Crustaceans (primarily amphipods) were
most abundant (44%) on the outer shelf relative to the inner (24%) and middle (38%)
shelf habitats. Molluscs represented a much smaller percentage of total taxonomic
abundance on the outer shelf (5%) relative to middle (17%) and inner (11%) shelf
habitats. Echinoderms also were more abundant on the outer shelf (3%) relative to the
middle (0.5%) and inner (0.4%) shelf.
Also shown in Figure 10 are the relative percentages (by numbers of taxa and abundance)
of taxonomic groups in estuaries of the Virginian Province. While the relative
percentages of most taxonomic groups (as percent of taxa) were similar, estuaries had
fewer polychaete taxa (34% vs. 43% in shelf waters) and higher numbers of 'Other' taxa,
mainly due to Oligochaetes and insect larvae found in low salinity estuarine habitats
(Table 8). In terms of percent of abundance, the relative percentage of polychaetes was
similar for estuaries and shelf waters (49% vs. 46%, respectively). However, relative
abundance (m~2) of crustaceans was much lower for estuaries (22% vs. 36% for shelf
waters), while molluscs were more abundant in estuaries (18% vs. 11%). While the
relative percent abundance of taxonomic groups varied among inner, mid, and outer shelf
waters, the taxonomic composition of estuaries, in terms of relative percent of abundance,
most resembled that of inner shelf waters.
D Other
D Echinodennata
• Mollusca
• Crustacea
• Polychaeta
MAB
Shelf Waters
B. Percent of Abundance
100
NCA
Estuaries
Inner Mid Outer
MAB Shelf Waters
MAB NCA Inner Mid Outer
Shelf Waters Estuaries MAB Shelf Waters
Figure 10. Relative percent composition of major taxonomic groups expressed as percent of total
taxa (A) and percent of abundance (B). Bar charts compare taxonomic composition throughout
MAB shelf waters with estuaries of the Virginian Province, sampled in 2005-2006 as part of the
U.S. EPA's National Coastal Assessment (NCA 2006). Additionally, MAB shelf waters are
further subdivided by depth into inner (-14-30 m), mid (30-50 m), and outer (50-100 m) shelf,
illustrating the transition from estuaries to outer shelf.
35
-------
Table 8. Summary of major taxonomic groups of benthic infauna and corresponding numbers of
identifiable taxa in samples (95 0.04-m2 grabs) from shelf waters of the MAB compared to
northeastern estuaries (353 0.04-m2 grabsT; NCA 2006).
Taxonomic Group
Phylum Annelida
Class Polychaeta
Class Clitellata
Subclass Oligochaeta*
Phylum Arthropoda
Subphylum Chelicerata*
Subphylum Crustacea
Class Malacostraca
Order Amphipoda
Order Cumacea
Order Decapoda
Order Isopoda
Order Lophogastrida
Order Mysida
Order Tanaidacea
Class Ostracoda
Class Thoracica*
Subphylum Hexapoda
Class Insecta*
Phylum Chordata*
Phylum Cnidaria
Class Anthozoa*
Class Hydrozoa*
Phylum Echinodermata
Class Asteroidea
Class Echinoidea
Class Holothuroidea
Class Ophiuroidea
Phylum Ectoprocta*
Phylum Hemichordata*
Phylum Mollusca
Class Aplacophora
Class Bivalvia
Class Gastropoda
Class Polyplacophora
Class Scaphopoda
Phylum Nemertea*
Phylum Phoronida*
Phylum Platyhelminthes*
Phylum Sipuncula*
Total
MAB
No. of
identifiable
taxa
162
2
2
66
19
4
10
0
0
3
15
0
0
2
2
0
4
3
3
3
1
1
1
51
19
0
0
3
1
1
3
381
2006
% of total
identifiable
taxa
42.5
0.5
0.5
17.3
5.0
1.0
2.6
0
0
0.8
3.9
0
0
0.5
0.5
0
1.0
0.8
0.8
0.8
0.3
0.3
0.3
13.4
5.0
0
0
0.8
0.3
0.3
0.8
100
NCA
No. of
identifiable
taxa
207
16
5
98
9
39
23
1
6
3
12
1
31
3
3
1
5
1
7
0
0
2
0
59
47
1
1
6
1
3
2
593
2005-2006
% of total
identifiable
taxa
34.9
2.7
0.9
16.5
1.5
6.6
3.9
0.2
1.0
0.5
2.0
0.2
5.2
0.5
0.5
0.2
0.8
0.2
1.2
0
0
0.4
0
9.9
7.9
0.2
0.2
1.0
0.2
0.5
0.3
100
' With the exception of 20 sites in Delaware Bay, sampled with a 0.1-m grab.
* Taxonomic groups followed by an asterisk were assigned to the group 'Other'
in Figure 1 1 .
36
-------
3.4.2 Abundance and Dominant Taxa
A total of 23,044 individuals were collected across the 48 stations (95, 0.04 m2 grabs)
sampled for benthos. Densities ranged from 675 - 29,263 m" and averaged 6,067 m"
(Table 9, Appendix E). On an area-weighted basis, 50 % of the survey area had mean
densities > 4,438 m"2 and 10 % of the area (upper 10th percentile) had mean densities >
11,843 m"2 (Table 9, Figure 11). The mean density of benthic macrofauna was fairly
consistent across the three depth zones (Figure 12B), although slightly higher (6,301 m"2)
for outer-shelf stations relative to middle- and inner-shelf stations (5,506 m" and 6,295
m"2, respectively). While the mean infaunal density in MAB coastal shelf waters (6,067
m"2) was similar to the mean density observed in northeast estuaries (6,052 m"2; NCA
2006), shelf densities were less variable (675 - 29,263 m" compared to 0 - 185,885 m"
for estuaries).
The 50 most abundant taxa collected throughout shelf waters in the MAB are listed in
Table 10. The top 10 dominants, in decreasing order of abundance, included the
amphipod Ampelisca agassizi, the polychaetes Polygordius spp. and Acmira catherinae,
tubuficid oligochaetes (Tubificidae), the amphipod Unciola irrorata, the polychaete
Spiophanes bombyx, the tanaid Tanaissuspsammophilus, the polychaetes Exogone hebes
and Goniadella gracilis, and maldanid polychaetes (Maldanidae).
Some cross-shelf trends in benthic dominance were noted (Figure 13). For example, the
overall top dominant, A. agassizi, did not appear in samples collected from the inner
shelf, but was the most abundant species in deeper mid- to outer-shelf waters. Mean
density of A agassizi increased from 565 m"2 to 1,551 m"2 in mid- and outer-shelf
sediments, respectively. The second dominant taxon overall (Polygordius spp.) was the
top dominant on the inner shelf, second dominant mid-shelf, and 29th on the outer shelf
999
(mean densities of 855 m" , 430 m" , and 41 m" , respectively). Acmira catherinae, the
third dominant overall, decreased in abundance from inner- (second dominant) to mid-
(21st) to outer- (22nd) shelf sediments, with mean densities of 718 m"2, 64 m"2, and 61 m"2,
respectively. Tubificid oligochaetes and the tanaid Tanaissuspsammophilus decreased
monotonically from the inner to outer shelf, while Unciola irrorata and Spiophanes
bombyx showed the reverse trend.
Patterns of dominance were markedly different for these offshore assemblages in
comparison to estuaries (Table 11). The top two offshore dominants (the amphipod
Ampelisca agassizi and the polychaete Polygordius spp.) were not found in estuaries.
Similarly, several of the remaining offshore dominants were found either in lower
densities in estuaries (Spiophanes bombyx: < 15 % of stations; Unciola irrorata, Exogone
hebes: < 10 % of stations) or rarely at all (Tanaissuspsammophilus, Goniadella gracilis:
< 1 % of stations). Conversely, the top two dominants in estuaries (the bivalve Gemma
gemma and the polychaete Streblospio benedictf) were not found at any sites in shelf
waters of the MAB. The amphipod Ampelisca abdita was rare at MAB sites, found at
only one site in very low densities (outer shelf, 3 specimens in one 0.04 m grab).
Mediomastus ambiseta and unidentified Mediomastus spp. were ranked as fourth and
fifth most abundant in estuaries, while the genus was much less common in offshore
37
-------
sediments (e.g., not among the 50 most abundant taxa). Tubificid oligochaetes as a group
were common to both offshore and estuarine sites, as was the bivalve Nuculaproximo,.
The remaining members of the ten highest ranked estuarine dominants were found either
in lower densities offshore (Tharyx acutus: 20 % of stations) or rarely if at all (Ampelisca
vadorum, Parasteropepollex: < 5 % of stations).
3.4.3 Diversity
A total of 381 taxa were identified (215 to species) in 95 grabs collected throughout the
study area. Taxonomic richness, expressed as the mean number of taxa present in
replicate 0.04 m2 grabs at a station, ranged from 9 to 50 taxa grab"1, with an overall mean
and median of 28 and 27 taxa grab"1, respectively (Table 9). Area-weighted percentiles
also are given in Table 9, and the full distribution of area-weighted estimates is illustrated
in Figure 11. Numbers of taxa in estuaries of the region typically were lower than
offshore waters, but varied by estuarine sub-region. For example, the number of taxa in
samples collected throughout estuaries of the Virginian Province averaged 18 taxa grab"1
and ranged from 0-62 taxa grab"1 (NCA 2006). However, the mean number of taxa at
sites exclusive of Chesapeake Bay was equal to 23 taxa grab"1, compared to only 12 taxa
grab"1 for Chesapeake Bay sites only (Table 9). This pattern also is reflected in the other
parameters presented in Table 9. Because of the large area of Chesapeake Bay in relation
to the rest of the Virginian Province (it represents 62 % of the area of the Province), it
tends to have a strong influence on calculated parameters (NCA 2006). Hence, benthic
parameters are presented in Table 9 for the estuaries of the region overall, for estuaries
exclusive of Chesapeake Bay, and for Chesapeake Bay only.
Numbers of taxa in coastal shelf sediments of the MAB were similar for inner (26 taxa
grab"1) and middle (25 taxa grab"1) shelf habitats, and highest among outer shelf sites (33
taxa grab"1). Diversity (H) generally increased seaward from inner (3.1) to middle (3.3)
to outer (3.6) shelf (Figure 12). Except for the similar numbers of taxa between inner-
and mid-shelf locations, these observations are consistent with those of Boesch (1979),
who found that both taxonomic richness and Shannon diversity increased across the shelf,
with the highest diversity occurring on the outer shelf.
The spatial distribution of values for taxonomic richness, density, and H' diversity in
relation to frequency-based percentiles (lower, mid, and upper quartiles) are shown in
Figs. 14 A, B, and C. Though there is some degree of variability in the data, most of the
low to intermediate values for taxonomic richness occurred along the middle and inner
shelf, with the majority of high values (above the upper quartile) occurring along the
outer shelf, as previously illustrated by the mean values shown in Figure 12A. Though
on average infaunal densities were slightly lower along the middle shelf, a clear density
pattern fails to emerge due to the large amount of variability that exists, as seen in the
overlapping confidence limits in Figure 12B. Most of the lowest values of H' diversity
(within the lower 10th percentile) occurred along the inner shelf, with higher diversity
along the outer shelf.
38
-------
Table 9. Mean, range, and selected distributional properties of key benthic variables. The MAB benthic measures represent 95 0.04-m2 grabs
collected at 48 sites (2 replicate grabs at every station except for station 14). The NCA benthic metrics represent 353 sites (one 0.04-m2 grab1^
collected at each station).
MAB (this study) c
Mean # Taxa/0.04 m2
Total # Taxa/0.08 m2
Mean Density (#/m2)
MeanHV0.04m2
Mid-Atlantic Estuaries
(NCA 2006)
# Taxa/0.04 m2
Density (#/m2)
H' 70.04 m2
Mid-Atlantic Estuaries,
Excluding Chesapeake
Bay (NCA 2006)
# Taxa/0.04 m2
Density (#/m2)
H' 70.04 m2
Mid-Atlantic Estuaries,
Chesapeake Bay Only
(NCA 2006)
# Taxa/0.04 m2
Density (#/m2)
H' 70.04 m2
Overall
Mean
28
42
6,067
3.4
18
6,052
2.6
23
8,842
2.87
12
2,300
2.32
Overall
Range
9-50
15 - 77
675 - 29,263
1.9 - 4.4
0 - 62
0 - 185,885
0 - 4.7
0 - 62
0 - 185,885
0.46- 4.7
0 - 36
0 - 12,261
0 - 4.25
Area-based Percentiles3
CDF CDF CDF
10th pctl 50th pctl 90th pctl
16
24
1,091
2.5
1
45
0.8
7
773
1.74
1
23
0.31
27
41
4,438
3.5
13
1,932
2.6
24
4,546
3.04
10
1,157
2.37
43
66
11,843
4.1
33
8,660
3.8
40
15,547
4.18
19
5,398
3.41
Frequency -based percentilesb
10th 25th 50th 75th
13
19
1,050
2.5
4
300
1.3
7
659
1.52
2
68
0.92
21
32
2,006
3.0
8
864
2.0
13
1,682
2.23
6
523
1.84
27 36
40 54
4,438 7,850
3.4 3.8
16 27
2,637 6,501
2.7 3.3
24 32
4,251 10,001
2.95 3.54
10 16
1,454 2,932
2.43 3.04
90th
44
67
12,938
4.1
36
14,047
3.9
40
21,866
4.03
24
6,205
3.53
f With the exception of 20 sites in Delaware Bay, sampled with a 0.1-m2 grab.
a Value of benthic variable corresponding to the designated cumulative % area of the estimated CDF.
b Corresponding lower 10th percentile, lower quartile, median, upper quartile, and upper 10th percentile of all values for each benthic variable.
0 Mean # taxa, mean density, and mean H' represent the average of each of those measures calculated separately for the two grabs at sites where replicates were taken. Total # taxa
is the total number of taxa in both replicate grabs combined (0.08 m2), except for station 14.
39
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Table 10. Fifty most abundant benthic taxa in the MAB 2006 survey region-wide. Mean density
(m~2), and percent frequency of occurrence are based on 95 0.04-m2 grabs. Classification: Native
= native species; Crypto = cryptogenic species (of uncertain origin); Indeter = indeterminate
taxon (not identified to a level that would allow determination of origin).
Taxon Name
Ampelisca agassizi
Polygordius spp.
Acmira catherinae
Tubificidae
Unciola irrorata
Spiophanes bombyx
Tanaissus psammophilus
Exogone hebes
Goniadella gracilis
Maldanidae
Cirratulidae
Protohaustorius wigleyi
Rhepoxynius hudsoni
Ampeliscidae
Leptocheims pinguis
Tellina agilis
Nucula proximo
Prionospio pygmaea
Chone spp.
Lumbrinerides acuta
Aricidea spp.
Unciola spp.
Scalibregma inflatum
Bivalvia
Ericthonius brasiliensis
Asabellides oculata
Nemertea
Nucula aegeensis
Amphiuridae
Cirrophorus spp.
Tellina spp.
Nephtyidae
Ampelisca spp.
Solemya velum
Levinsenia gracilis
Byblis serrata
Ninoe nigripes
Acanthohaustorius millsi
Aricidea wassi
Ophiuroidea
Spionidae
Caulleriella spp.
Ampharetidae
Protohaustorius spp.
Aricidea cerrutii
Parapionosyllis longicirrata
Astarte spp.
Crassicorophium crassicorne
Euchone incolor
Enchytraeidae
Group
Amphipod
Polychaete
Polychaete
Oligochaete
Amphipod
Polychaete
Tanaid
Polychaete
Polychaete
Polychaete
Polychaete
Amphipod
Amphipod
Amphipod
Amphipod
Bivalve
Bivalve
Polychaete
Polychaete
Polychaete
Polychaete
Amphipod
Polychaete
Bivalve
Amphipod
Polychaete
Nermertean
Bivalve
Echinoderm
Polychaete
Bivalve
Polychaete
Amphipod
Bivalve
Polychaete
Amphipod
Polychaete
Amphipod
Polychaete
Echinoderm
Polychaete
Polychaete
Polychaete
Amphipod
Polychaete
Polychaete
Bivalve
Amphipod
Polychaete
Oligochaete
Classification
Native
Indeter
Native
Indeter
Native
Crypto
Native
Native
Native
Indeter
Indeter
Native
Native
Indeter
Native
Native
Native
Native
Indeter
Native
Indeter
Indeter
Native
Indeter
Native
Native
Indeter
Native
Indeter
Indeter
Indeter
Indeter
Indeter
Native
Native
Native
Native
Native
Native
Indeter
Indeter
Indeter
Indeter
Indeter
Native
Native
Indeter
Native
Native
Indeter
Mean Density
754.2
422.1
276.3
241.3
212.4
210.3
178.9
168.2
164.5
143.2
103.9
98.4
97.1
92.1
91.6
89.2
86.3
85.0
85.0
79.7
72.9
67.6
63.4
63.4
62.4
58.7
53.2
50.8
46.6
46.1
46.1
43.2
39.2
38.9
36.6
34.5
33.9
33.2
32.6
32.6
28.9
27.6
27.1
27.1
26.6
26.3
25.8
25.3
25.3
24.7
Frequency (%)
21.1
68.4
44.2
60.0
47.4
44.2
44.2
41.1
35.8
58.9
64.2
22.1
46.3
10.5
14.7
4.2
12.6
9.5
26.3
23.2
52.6
17.9
43.2
57.9
13.7
8.4
50.5
5.3
5.3
26.3
15.8
50.5
13.7
3.2
15.8
28.4
17.9
9.5
18.9
9.5
26.3
28.4
36.8
1.1
15.8
26.3
5.3
7.4
11.6
24.2
40
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Table 11. Fifty most abundant benthic taxa collected in northeast estuaries in 2005-2006 (NCA
2006). Mean density (m~2), and percent frequency of occurrence are based on 353 0.04-m grabsT
Classification: Native = native species; Crypto = cryptogenic species (of uncertain origin);
Indeter = indeterminate taxon (not identified to a level that would allow determination of origin).
Taxon Name
Gemma gemma
Streblospio benedicti
Ampelisca abdita
Mediomastus ambiseta
Mediomastus spp.
Tubificidae
Nucula proximo
Tharyx acutus
Ampelisca vadorum
Parasterope pollex
Crepidula fornicata
Heteromastus filiformis
Schizobranchia insignis
Acmira catherinae
Ampelisca verrilli
Ennucula tennis
Ampelisca spp.
Spiochaetopterus oculatus
Glycinde solitaria
Polydora cornuta
Levinsenia gracilis
Bivalvia
Acteocina canaliculata
Nephtys incisa
Crepidula spp.
Neanthes succinea
Leitoscoloplos spp.
Tubificoides spp.
Leptocheims plumulosus
Scoloplos robustus
Sabellaria vulgaris
Corophium lacustre
Lumbrineris tennis
Paraprionospio pinnata
Maldanidae
Capitella capitata
Cirratulidae
Mulinia lateralis
Cerapus tubularis
Limnodrilus spp.
Tellina agilis
Mytilus edulis
Microdeutopus gryllotalpa
Pygospio elegans
Elasmopus laevis
Nephtys spp.
Leptocheims pinguis
Eusarsiella zostericola
Cyathura polita
Polydora socialis
Group
Bivalve
Polychaete
Amphipod
Polychaete
Polychaete
Oligochaeta
Bivalve
Polychaete
Amphipod
Ostracod
Gastropod
Polychaete
Polychaete
Polychaete
Amphipod
Bivalve
Amphipod
Polychaete
Polychaete
Polychaete
Polychaete
Bivalve
Gastropod
Polychaete
Gastropod
Polychaete
Polychaete
Oligochaete
Amphipod
Polychaete
Polychaete
Amphipod
Polychaete
Polychaete
Polychaete
Polychaete
Polychaete
Bivalve
Amphipod
Oligochaeta
Bivalve
Bivalve
Amphipod
Polychaete
Amphipod
Polychaete
Amphipod
Ostracod
Isopod
Polychaete
Classification
Native
Native
Native
Native
Indeter
Indeter
Native
Native
Native
Native
Native
Native
Native
Native
Native
Native
Indeter
Native
Native
Native
Native
Indeter
Native
Native
Indeter
Native
Indeter
Indeter
Native
Native
Native
Native
Native
Native
Indeter
Native
Indeter
Native
Native
Indeter
Native
Native
Native
Native
Native
Indeter
Native
Native
Native
Native
Mean Density
578.8
478.6
456.5
434.5
327.4
311.4
189.8
183.9
136.8
119.5
108.8
100.3
84.7
81.7
77.5
71.1
68.8
65.7
62.9
62.7
62.6
53.8
52.9
52.0
48.6
47.5
44.0
43.9
40.3
39.2
39.1
36.0
35.9
35.3
34.9
33.9
31.6
31.3
31.1
29.3
28.9
27.0
26.6
25.9
25.8
25.5
23.6
21.2
20.4
19.9
Frequency (%)
9.5
40.3
17.9
45.5
39.8
42.7
17.0
23.6
11.2
14.4
7.5
35.2
4.6
13.5
13.3
1.7
18.2
16.7
37.8
17.9
10.1
28.0
24.2
17.3
7.8
24.8
28.0
9.5
8.6
20.2
7.5
2.0
12.7
21.9
20.5
8.4
17.0
11.8
4.3
2.9
17.0
2.3
4.0
2.0
8.4
13.0
4.3
17.3
14.7
5.5
With the exception of 20 sites in Delaware Bay, sampled with a 0.1-m2 grab.
41
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A.
100-
80-
C3
i
< 60-
E 40-
CJ
20-
0-1
10
20 30 40
Mean # taxa/0.04 nr
SO
B.
100-
80-
a
< 60-
E 40-
0
20-
o-l
IxlO4
2xl04
3x104
c.
Mean Density (#/m2)
100-
80-
< 60-
E 40-
20-
0-
I
2.0
I
3.0
4.0
Mean HV0.04 nr
Figure 11. Percent area (and 95% C.I.) of MAB shelf waters vs. benthic infaunal taxonomic
richness (A), density (B), and FT diversity (C).
42
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A.
40-
3 30-
1
2 20-
10-
B.
10000
c.
H
1
Innoi'
Mid
Outer
Inner
Mid
Outer
Inner
Mid
Outer
Figure 12. Comparison of A) benthic taxonomic richness (mean # taxa/0.04 m2), B) density
(mean # individuals/m2), and C) diversity (mean H70.04 m2) among inner, middle, and outer shelf
locations. Whiskers represent upper 95% confidence limits for the sample mean.
43
-------
1500-
£
*
CJ
5
CJ
1000-
5 500-
0-
o
D
O
A
D
Inner
Shelf
Antpelisca agassizi
Polygardius spp.
Acmira catlierinae
Tubificidae
Unciola irroruta
Spiophanes bombyx
Tanaissus psammophilus
Mid
Shelf
Outer
Shelf
Figure 13. Trends in mean densities (#/m2) of dominant taxa collected in sediments from
relatively shallow (< 30 m) inner-shelf waters to deeper mid- (30 - 50 m) and outer- (> 50 m)
shelf waters of the MAB.
44
-------
76°W
74°W
72°W
70°W
Mean # taxa/grab
21 (lower quartile)
- 27 {lower-mid quartile)
- 36 (mid-upper quarlile)
(upper quarlile)
L36°N
74=\\
72°W
70°W
Figure 14. A. Spatial distribution of benthic taxonomic richness (mean # taxa/0.04 m2). Values
within the lower 10th percentile of all values are also flagged with an asterisk (*).
45
-------
36°N
76°W
74°W
72°W
70°W
o
Mean Density (# md/sq m)
• <= 2006 (lower quartile)
O >2006 - 4438 (lower-mid quanile)
O >4438 - 7850 (mid-upper quanile)
* >7850 (upper quanile)
-40°N
•38°N
-36°N
74°W
72"W
70°\V
Figure 14. B. Spatial distribution of benthic infaunal density (mean # individuals/m2). Values
within the lower 10th percentile of all values are also flagged with an asterisk (*).
46
-------
36°N
76°W
74°W
72°W
70°W
Mean H/grab
• <=3.0 (lower quart i Ic)
O >3.0 - 3.4 (lower - mid quartile)
O >3,4 - 3.8 (mid - upper quartile)
• >3.81 upper quartile)
•40°N
•38°N
•36°N
74°W
72°W
70°W
Figure 14. C. Spatial distribution of benthic taxonomic diversity (mean H70.04 m2). Values
within the lower 10th percentile of all values are also flagged with an asterisk (*).
47
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3.4.4 Non-indigenous Species
The list of taxa collected in coastal shelf waters of the MAB was examined for the
occurrence of non-native and exotic species by searching NISbase, a distributed database
on non-indigenous species that queries a number of different information systems.
Databases that are part of NISbase include the U.S. Geological Survey (USGS) National
Aquatic Species Database (NAS, U.S. Geological Survey 2004), the Smithsonian
National Exotic Marine and Estuarine Species Information System (NEMESIS, Fofonoff
et al. 2003), the Massachusetts Institute of Technology Sea Grant Program Marine
Invader Tracking Information System (MITIS, MIT 2008), and the NOAA National
Benthic Inventory (NBI 2004), among others. While a small number of species collected
as part of the 2006 MAB survey (Harmothoe imbricata, Spiophanes bombyx, and
possibly Leptochelia dubia, but not identified to species) are considered to be cryptogenic
(Ruiz et al. 2000), none were found unequivocally to be non-indigenous to the area.
By comparison, a few cryptogenic (Boccardiella ligerica, Corophium acherusicuni) and
non-indigenous (Branchiura sowerbyi, Corbicula flumined) benthic infaunal species were
identified in mid-Atlantic estuaries (NCA 2006). These estuarine non-indigenous species
would not be expected to occur offshore since the shelf environment would be outside of
their normal (lower) salinity ranges.
3.5 Potential Linkage of Biological Condition to Stressor Impacts
Multi-metric benthic indices are commonly used to summarize and classify benthic
habitat conditions along the continuum from non-degraded to degraded (see review by
Diaz et al. 2004) and have been developed for a variety of estuarine applications (Engle
et al. 1994, Weisberg et al. 1997, Van Dolah et al. 1999, Llanso et al. 2002a, 2002b, Hale
and Heltshe 2008). A desired characteristic of these indices is the ability to discriminate
between impaired versus unimpaired benthic condition, based on key biological attributes
(e.g., numbers of species, diversity, abundance, biomass, relative proportion of pollution-
sensitive or pollution-tolerant species), while taking into account natural controlling
factors. Such indices have been developed for estuaries of the mid-Atlantic states and
Chesapeake Bay (Weisberg et al. 1997, Llanso et al. 2002a, 2002b). An index is being
developed for near-coastal NJ (to 3 km; Strobel et al. 2008), but no such index exists for
coastal shelf waters of the mid-Atlantic region.
In the absence of a benthic index, we attempted to assess potential stressor impacts in the
present study by evaluating linkages between reduced values of biological attributes
(numbers of taxa, diversity, and abundance) and synoptically measured indicators of poor
sediment or water quality. Using the lower 10* percentile as a basis for defining 'low'
values, we looked for co-occurrences of low values of biological attributes with
indications of poor sediment or water quality defined as follows (sensu U.S. EPA 2000b
for dissolved oxygen, U.S. EPA 2004 for other indicators): > 1 chemical in excess of
ERMs (from Long et al. 1995a), TOC > 50 mg/g, and DO in near-bottom water < 2.0
mg/L.
48
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The analysis found no association of low values of biological attributes (as defined
above) with indicators of poor sediment or water quality. In fact, no indications of poor
sediment or water quality were observed based on these criteria. The highest observed
TOC concentration was 16 mg/g (Appendix A), well below 50 mg/g as well as the more
conservative bioeffect threshold of 35 mg/g TOC published in Hyland et al. (2005). DO
concentrations in bottom waters were at least 8.1 mg/L (Appendix B) and no ERM
exceedances were observed (Appendix D). These results suggest that coastal shelf waters
of the MAB are in good condition, with lower-end values of biological attributes
(Appendix E) representing parts of a normal reference range controlled by natural factors.
Multiple linear regression was used to assess the relationship of each of the benthic
variables to various abiotic environmental factors (depth, latitude, percent fines).
Appropriate data transformations were applied where needed (i.e., logic for density) to
meet analysis assumptions. While none of the relationships were significant for either
density or taxonomic richness, all three abiotic factors showed a significant effect on H'
diversity (at a = 0.05 level of significance). Benthic diversity was higher among deeper
sites (p = 0.0001), lower latitudes (p = 0.0164), and lower percent fines (p = 0.0010).
Alternatively, it is possible that for some of these sites the lower values of benthic
variables reflect symptoms of disturbance induced by other unmeasured stressors. In
efforts to be consistent with the underlying concepts and protocols of earlier EMAP and
NCA programs, the indicators in this study included measures of stressors, such as
chemical contaminants and symptoms of eutrophication, which are often associated with
adverse biological impacts in shallower estuarine and inland ecosystems. However, there
may be other sources of human-induced stress in these offshore systems, particularly
those causing physical disruption of the seafloor (e.g., commercial bottom trawling, cable
placement, minerals extraction), that pose greater risks to living resources and which
have not been adequately captured. Future monitoring efforts in these offshore areas
should include indicators of such alternative sources of disturbance.
49
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55
-------
5.0 Appendices
56
-------
Appendix A. Locations (latitude, longitude), depth, and sediment characteristics of sampling
stations.
Station
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
17
18
19
20
21
22
23
24
25
26
27
28
29
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
47
48
49
50
90
98
Latitude
39.77623
38.19041
40.62198
40.16709
39.84345
37.35055
38.71867
40.60671
39.57371
37.39598
39.21100
40.48423
40.42264
36.22157
39.27211
39.32492
37.96872
38.31449
41.23268
40.47603
36.02088
38.98426
40.86574
40.23471
37.01197
38.66862
40.78832
40.52200
37.76414
40.43062
39.70231
38.00765
40.38298
41.19415
40.20558
36.54718
38.75957
41.18448
40.26110
37.08104
38.97416
40.53967
40.89256
38.69160
40.28228
39.41574
36.74786
40.93569
41.10785
Longitude
-73.85195
-74.48682
-72.01708
-69.84248
-72.38011
-74.92469
-73.71866
-69.04485
-72.93307
-75.20685
-74.12418
-70.43420
-73.47158
-75.59648
-72.94964
-74.07539
-74.38807
-74.29424
-71.08608
-72.86645
-75.49837
-73.72332
-69.59671
-73.44134
-75.05770
-74.77945
-70.61688
-71.54149
-75.23725
-68.69903
-73.45761
-74.92921
-72.34644
-71.13901
-71.77030
-75.28401
-73.56624
-70.22600
-72.39044
-75.21376
-74.74604
-71.01903
-71.87329
-74.94115
-69.21308
-74.25471
-75.69260
-69.55392
-69.62802
Depth
(m)
26.0
42.0
55.4
98.3
75.0
39.6
48.8
71.0
62.0
28.1
24.0
70.0
24.8
26.3
70.0
24.0
56.0
51.6
42.0
42.0
26.0
43.0
37.0
35.3
41.0
14.3
57.0
76.6
20.5
88.0
33.2
26.0
55.0
38.0
80.0
25.0
60.0
26.0
58.0
35.0
13.6
75.0
38.7
17.6
92.2
16.0
20.5
42.0
31.2
TOC
mg/g
0.46
0.38
0.62
3.42
1.96
0.76
0.94
0.52
0.60
0.80
0.41
9.63
0.93
1.32
1.21
1.23
1.59
1.54
4.91
0.95
0.70
0.91
0.56
0.72
0.63
0.40
5.86
11.07
0.39
2.12
0.31
0.36
0.33
0.63
4.74
0.27
1.72
0.42
0.69
1.34
0.33
16.04
0.41
2.92
3.23
0.34
0.44
0.28
-
%
Sand
99.5
99.5
98.8
79.3
93.0
99.7
98.4
99.0
98.6
99.1
49.8
99.5
99.4
96.1
98.7
99.6
97.9
97.4
82.4
99.0
99.2
99.1
99.6
99.2
99.8
99.6
68.8
80.8
99.1
95.6
99.5
99.4
99.1
99.4
80.5
99.6
96.8
99.1
98.4
98.9
99.8
13.2
99.7
86.1
92.0
99.7
99.4
99.8
-
%
Silt-clay
0.5
0.6
1.2
20.7
7.0
0.3
1.6
1.1
1.4
0.9
50.2
0.5
0.6
3.9
1.4
0.4
2.1
2.6
17.6
1.0
0.8
0.9
0.4
0.8
0.2
0.4
31.2
19.2
0.9
4.4
0.5
0.6
0.9
0.6
19.6
0.5
3.2
0.9
1.6
1.2
0.3
86.9
0.3
13.9
8.0
0.3
0.7
0.3
-
57
-------
Appendix B. Near-bottom water characteristics by station.
Station
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
17
18
19
20
21
22
23
24
25
26
27
28
29
31
32
Temp.
(°C)
10.4
9.8
7.4
13.2
12.3
9.5
11.0
7.3
7.9
11.0
10.8
7.7
10.1
11.7
12.9
11.2
13.6
11.0
8.3
8.5
12.0
8O
.3
8.3
9.2
9.7
13.1
6.9
6.9
12.7
8.2
Salinity
(psu)
31.9
32.9
32.5
35.0
34.3
33.5
34.1
32.6
33.2
32.5
32.3
33.0
31.2
32.5
34.7
32.4
35.0
34.1
32.3
32.1
32.4
32.8
32.3
32.1
33.2
31.5
32.7
33.3
31.9
33.4
DO
(mg/L)
9.1
9.2
9.7
8.4
8.6
9.2
8.9
9.7
9.6
9.0
9.0
9.6
9.2
8.9
8.5
8.9
8.4
8.9
8.4
9.5
8.8
9.5
9.5
9.4
9.2
8.7
9.8
9.8
8.7
9.5
pH
8.1
-
8.4
8.5
8.3
-
-
8.5
-
-
-
8.5
8.2
-
-
-
-
-
8.0
8.2
-
-
8.6
8.2
-
-
8.4
8.3
-
8.5
DIP
(mg/L)
0.036
0.046
0.055
0.069
0.064
0.056
0.065
0.067
0.083
0.037
0.039
0.067
0.046
0.039
0.060
0.042
0.049
0.064
0.056
0.054
0.047
0.062
0.048
0.048
0.055
0.028
0.074
0.120
0.037
0.077
DIN
(mg/L)
0.032
0.027
0.054
0.412
0.234
0.101
0.222
0.187
0.230
0.024
0.025
0.159
0.037
0.027
0.221
0.019
0.142
0.184
0.042
0.044
0.034
0.079
0.062
0.030
0.114
0.014
0.178
0.539
0.016
0.349
Nitrate+
Nitrite
(Hg/L)
22.6
27.0
51.1
405.9
231.2
98.4
218.7
160.4
200.7
20.8
24.3
116.0
26.6
26.7
210.9
18.2
131.7
179.1
31.5
40.0
28.8
69.8
51.2
28.9
106.7
9.1
134.0
464.6
11.6
310.7
Ammonium
(Hg/L)
9.2
0.4
2.5
5.8
2.5
2.5
3.8
27.0
29.3
3.1
0.7
43.4
10.9
0.8
10.2
0.4
10.6
5.0
10.4
3.9
5.3
8.9
10.4
0.6
7.1
4.6
43.9
74.0
4.6
37.9
N/P
2.35
0.97
1.70
9.82
6.00
3.04
5.69
5.93
5.74
1.35
1.10
6.15
2.18
1.18
6.60
0.73
5.48
4.91
1.87
1.56
1.57
2.59
2.82
1.01
3.75
1.44
5.97
9.37
1.17
8.99
Silicate
(fig/L)
294.8
354.5
454.7
631.1
592.9
388.2
562.1
469.6
714.8
261.2
228.6
446.2
468.6
394.8
588.3
164.9
414.4
481.7
495.4
393.2
209.0
359.3
300.4
326.6
358.1
210.3
662.1
1239.4
254.9
578.6
Chlorophyll a
(fig/L)
0.216
0.075
0.018
0.041
0.051
0.732
-
0.896
0.238
0.412
0.147
0.827
0.164
0.886
0.081
0.104
0.196
0.028
0.050
0.034
0.058
0.043
0.037
0.034
0.267
0.038
0.008
0.051
0.053
0.065
TSS
(mg/L)
6.0
8.2
4.3
6.5
1.8
5.6
-
3.0
3.6
7.0
6.8
9.6
3.9
5.7
3.8
5.0
3.0
9.4
4.1
5.1
8.0
3.6
1.1
11.4
5.6
10.6
12.8
4.8
14.5
2.0
58
-------
Appendix B (continued).
Station
33
34
35
36
37
38
39
40
41
42
43
44
45
47
48
49
50
90
98
Temp.
(°C)
8.9
12.5
6.6
8.3
12.6
11.1
13.5
9.8
6.5
11.1
13.6
12.1
8.8
13.9
8.3
13.6
12.4
7.7
8.8
Salinity
(psu)
32.2
32.1
32.6
32.3
34.9
32.9
34.9
32.1
32.5
32.7
30.6
34.4
32.2
31.2
33.5
30.0
32.1
32.3
32.2
DO
(mg/L)
9.4
8.7
9.9
8.6
8.6
8.9
8.4
8.9
9.9
9.0
8.6
8.7
9.4
8.5
9.5
8.6
8.7
9.7
9.5
pH
-
-
8.2
8.0
8.3
-
-
8.1
8.2
-
-
8.5
-
-
8.6
-
-
8.6
8.6
DIP
(mg/L)
0.054
0.031
0.084
0.037
0.079
0.040
0.051
0.038
0.088
0.041
0.021
0.062
0.045
0.034
0.078
0.017
0.037
0.059
0.042
DIN
(mg/L)
0.035
0.021
0.262
0.018
0.542
0.019
0.199
0.013
0.278
0.021
0.008
0.261
0.030
0.040
0.366
0.014
0.022
0.200
0.034
Nitrate+
Nitrite
(Hg/L)
28.1
13.3
231.8
16.0
539.9
18.3
181.7
11.1
241.4
20.6
6.9
232.7
17.3
12.6
329.1
13.6
14.5
181.7
32.7
Ammonium
(Hg/L)
7.3
7.4
30.5
2.1
2.5
0.6
17.3
1.5
36.3
0.3
1.1
28.4
13.0
27.9
36.6
0.5
7.4
18.6
0.9
N/P
1.55
1.98
6.28
0.98
10.88
0.80
7.43
0.68
6.51
0.84
0.83
8.45
2.18
4.95
9.18
1.45
1.70
6.46
1.38
Silicate
(ug/L)
305.1
241.0
664.9
171.3
766.3
485.7
466.9
252.2
759.7
392.5
123.0
482.8
270.8
240.2
614.5
118.1
223.3
384.2
252.3
Chlorophyll a
(ug/L)
0.450
0.761
0.144
0.019
0.359
0.085
0.049
0.046
0.022
0.009
0.422
0.043
0.036
3.023
0.540
0.129
1.829
0.150
0.195
TSS
(mg/L)
5.0
5.4
5.0
4.3
1.6
6.2
6.1
11.8
2.9
5.1
12.7
1.8
6.4
36.4
16.3
10.4
6.5
4.6
6.6
59
-------
Appendix C. Near-surface water characteristics by station.
Station
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
17
18
19
20
21
22
23
24
25
26
27
28
29
31
32
Temp.
(°C)
11.8
11.0
10.0
17.9
10.9
11.2
11.1
8.7
10.9
12.8
11.6
9.8
10.7
14.3
14.7
12.2
12.2
11.2
11.0
10.7
12.9
10.9
8.3
10.8
12.4
13.6
10.2
9.8
14.3
9.5
Salinity
(psu)
31.6
32.8
32.4
35.3
32.3
32.9
32.8
32.4
32.1
32.3
32.0
32.4
31.2
31.2
34.1
31.6
33.7
32.8
31.9
31.4
31.8
32.6
32.3
31.9
32.6
31.5
32.5
32.5
31.8
32.7
DO
(mg/L)
8.9
9.0
9.2
7.7
9.0
8.9
8.9
9.4
9.0
8.6
8.9
9.2
9.1
8.4
8.2
8.8
8.7
8.9
8.8
9.1
8.7
9.0
9.5
9.0
8.7
8.6
9.1
9.2
8.4
9.3
pH
8.2
-
8.4
8.6
8.3
-
-
8.6
-
-
-
8.5
8.2
-
-
-
-
-
8.1
8.2
-
-
8.6
8.2
-
-
8.6
8.4
-
8.6
DIP
(mg/L)
0.034
0.042
0.033
0.024
0.038
0.043
0.040
0.055
0.040
0.034
0.036
0.038
0.044
0.033
0.033
0.042
0.038
0.044
0.042
0.042
0.039
0.043
0.050
0.042
0.037
0.031
0.034
0.042
0.033
0.050
DIN
(mg/L)
0.026
0.037
0.027
0.053
0.026
0.032
0.039
0.096
0.036
0.034
0.025
0.030
0.022
0.033
0.024
0.035
0.022
0.031
0.028
0.019
0.054
0.024
0.071
0.027
0.019
0.014
0.010
0.021
0.033
0.110
Nitrate+
Nitrite
(Hg/L)
21.6
27.5
26.0
43.1
22.6
23.2
36.2
95.1
25.6
33.6
24.7
23.4
22.4
30.7
21.7
30.4
17.8
30.0
25.7
18.3
49.8
20.6
54.6
26.1
17.9
12.2
9.2
20.3
15.1
102.6
Ammonium
(Hg/L)
4.1
9.0
1.1
9.7
3.1
9.1
3.1
0.7
10.0
0.5
0.1
6.4
0.1
1.8
2.6
4.8
4.2
0.6
2.0
0.8
4.0
3.4
16.8
1.3
1.0
2.2
0.9
0.9
18.1
7.1
N/P
1.65
2.17
1.44
5.23
1.39
2.01
1.85
2.84
2.34
1.67
1.12
1.91
0.85
1.75
1.48
1.77
1.35
1.17
1.25
0.81
2.53
1.18
3.53
1.17
0.91
1.04
0.61
0.98
3.73
3.97
Silicate
(fig/L)
417.0
277.3
617.4
312.6
149.8
239.6
497.6
349.8
187.2
755.6
259.3
113.5
741.1
396.7
660.2
250.9
248.1
413.5
228.4
787.3
167.7
206.9
315.2
299.5
214.6
634.2
165.7
505.9
650.9
377.6
Chlorophyll a
(fig/L)
0.342
0.043
0.146
0.187
0.195
0.044
-
0.387
0.177
0.085
0.562
0.094
0.047
0.033
0.185
0.070
0.018
0.068
0.091
0.032
0.049
0.039
0.022
0.163
0.076
0.660
0.708
0.012
0.112
0.118
TSS
(mg/L)
4.9
5.4
5.1
4.6
3.4
4.2
-
0.9
6.9
6.8
3.3
6.6
11.3
6.3
4.7
3.8
2.5
4.2
3.4
6.3
11.6
4.3
0.9
3.2
8.1
13.5
8.6
3.9
7.7
1.3
60
-------
Appendix C (continued).
Station
33
34
35
36
37
38
39
40
41
42
43
44
45
47
48
49
50
90
98
Temp.
(°C)
11.4
12.8
9.9
11.2
9.9
12.2
14.7
10.1
9.9
12.8
13.6
11.0
11.1
14.7
9.3
13.7
15.2
7.8
8.8
Salinity
(psu)
31.8
32.0
32.2
31.9
32.4
32.8
34.4
31.9
32.1
32.6
30.6
33.3
31.2
30.5
32.7
30.0
30.4
32.3
32.2
DO
(mg/L)
8.9
8.7
9.2
8.7
9.2
8.7
8.2
8.9
9.2
8.6
8.6
8.9
9.0
8.4
9.3
8.6
8.3
9.7
9.4
pH
8.3
8.1
8.4
8.1
8.3
8.5
8.5
8.6
8.6
DIP
(mg/L)
0.040
0.029
0.052
0.050
0.056
0.041
0.034
0.045
0.037
0.039
0.020
0.032
0.045
0.031
0.050
0.015
0.026
0.060
0.041
DIN
(mg/L)
0.021
0.022
0.014
0.024
0.051
0.027
0.019
0.022
0.011
0.014
0.014
0.017
0.024
0.028
0.132
0.014
0.011
0.199
0.051
Nitrate+
Nitrite
(Hg/L)
14.5
12.0
13.8
19.8
29.1
17.4
17.5
14.2
11.4
12.1
11.7
10.6
17.9
21.3
124.1
12.8
9.7
181.3
39.1
Ammonium
(Hg/L)
6.0
10.4
0.1
3.9
21.8
9.9
1.0
7.6
0.1
2.1
2.2
6.7
6.2
6.9
7.6
1.6
1.2
17.3
12.0
N/P
1.37
2.55
0.43
1.05
2.90
1.96
1.01
1.41
0.50
0.78
1.56
1.65
1.44
2.28
4.74
1.93
0.84
6.25
3.14
Silicate
(|Ag/L)
227.1
260.5
224.7
285.6
461.3
494.8
514.3
338.6
221.5
199.2
626.8
108.1
830.4
409.5
378.7
94.5
157.8
374.5
437.7
Chlorophyll a
(fig/L)
0.066
0.049
0.181
0.115
0.129
0.012
0.086
0.024
0.028
0.025
0.150
0.042
0.017
3.303
0.116
0.325
0.767
0.610
0.074
TSS
(mg/L)
2.1
4.0
4.3
2.2
3.0
5.9
5.6
4.8
4.8
12.2
10.1
2.2
8.5
6.9
10.2
6.5
6.9
6.7
6.2
61
-------
Appendix D. Summary by station of mean ERM quotients and the number of contaminants that
exceeded corresponding ERL or ERM values (from Long et al. 1995a).
Station
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
17
18
19
20
21
22
23
24
25
26
27
28
29
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
47
48
49
50
90
#ofERLs
Exceeded
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
#ofERMs
Exceeded
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Mean
ERM-Q
0.002
0.002
0.009
0.009
0.007
0.001
0.004
0.001
0.008
0.005
0.003
0.018
0.010
0.011
0.004
0.009
0.006
0.005
0.008
0.002
0.001
0.002
0.001
0.008
0.001
0.003
0.008
0.019
0.006
0.004
0.007
0.005
0.003
0.002
0.007
0.003
0.006
0.001
0.003
0.006
0.001
0.026
0.002
0.017
0.007
0.001
0.003
0.001
62
-------
Appendix E. Summary by station of benthic macroinfaunal (>0.5mm) characteristics. Two
replicate benthic grabs (0.04m2 each) were processed from each station, except for station 14 (see
text). H' derived using base 2 logarithms. (*Values within lower 25th percentile of all values of a
specific benthic variable; **values within lower 10th percentile.)
Station
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
17
18
19
20
21
22
23
24
25
26
27
28
29
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
47
48
49
50
90
Mean # Taxa
per Grab
27
24
44
25
50
35
27
22
33
21
11**
27
23
32
20*
30
43
37
43
20*
38
15*
11**
30
24
9**
50
11**
36
44
18*
37
36
28
24
21*
38
31
28
31
23
17*
26
33
50
20*
28
13**
Total # Taxa
38
36
56
38
77
54
42
33
51
34
16**
44
36
32*
31*
44
63
61
69
32*
61
24*
17**
47
36
15**
71
19**
53
67
25*
59
52
39
42
34
56
45
40
31*
34
31*
40
47
77
29*
41
17**
Mean Density
(# / m2)
9288
1188*
8138
4275
9000
4125
4788
1650*
2900
4363
1513*
2788
3638
6350
825**
5075
9063
8413
29263
1250*
5988
750**
1050**
7450
2363
675**
22388
1488*
4900
7638
938**
7463
4463
6438
2600
2525
8063
23238
4413
9088
3588
1263*
7013
12938
14063
2563
6613
1388*
MeanH'
per Grab
2.4**
4.1
4.2
3.1
4.0
4.1
2.7*
4.1
4.4
3.2
1 9**
4.1
o o
J.J
3.1
4.1
3.8
3.7
3.4
3.2
3.6
3.9
3.5
2.7*
2.4**
3.9
2.5*
2.8*
2.4**
3.9
3.6
3.7
3.5
4.1
o o
J.J
3.7
3.6
2.8*
2.5*
3.7
3.6
3.1
3.2
2.9*
3.2
3.0
2.7*
3.1
3.1
63
-------
64
-------
\
v^"'/
0?
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