Product Citations and Abstracts

The EMAP program has been organized into three primary elements: Multi-Tier Design, Indicator, and Index Sites. The Index Sites program (DISPro - Demonstration Intensive Site Project) is the primary activity within the Index Sites element of EMAP. This project represents an inter-agency effort between EPA/ORD and DOI/NPS to develop a demonstration of an intensive site network of monitoring and research locations throughout the United States, utilizing the Nation's parklands as "outdoor laboratories". Twelve parks were selected to establish this demonstration. These 12 parks were selected because they are readily accessible, have a history of monitoring environmental information, and represent a broad spectrum of ecological communities. EMAP, through DISPro, is examining whether a "network" of sites existing within the parks can be used to address monitoring issues for global-scale environmental stressors (e.g., air pollution) as well as locale-specific stressors (e.g., air deposition, water-borne) and coordinated with cause-effect, issue-based research related to these environmental stressors. As a first activity, EPA will provide each of the sites with the instrumentation to monitor UV-B. The intent of the program is to initiate a consistent air monitoring program at each site to be followed by consistent monitoring within other media. The project will initiate research projects at all the sites (eventually) to examine the effects of environmental stressors of importance at each of the sites.

Summers, Kevin, John Carlton and Steve Heath. 1998. Developing a Multi-Agency 305(b) Monitoring Program for the Coastal Waters of Alabama. In: Proceedings of the NWQMC National Conference: Monitoring: Critical Foundations to Protect Our Waters. U.S. Environmental Protection Agency, Washington, DC. Pp. III-595-III-614. (ERL,GB 1047).

With the ability of many federal agencies to maintain long-term coastal monitoring in jeopardy due to shrinking budgets, many states are beginning to re-examine their coastal and freshwater monitoring programs. This re-examination focuses primarily on the potential to design or re-design programs to attain multiple objectives through multi-agency interactions. This presentation documents the efforts of Alabama resource agencies to incorporate the monitoring activities of several freshwater and coastal state agencies and private industries into a coordinated, comprehensive water quality monitoring program. A key element of the comprehensive monitoring plan includes the use of biological indicators in addition to the traditional physical and chemical variables measured in the past. A key part of this effort involved the interactions between state and federal agencies, their interactions with academic researchers and the public to draw upon as large a knowledge base as possible. The process by which a multi-faceted, multi-objective comprehensive monitoring plan for Alabama waters was developed and implemented is described.

Summers, Kevin, Andrew Robertson and Barbara Levinson. 2000. Development of the Coastal Intensive Site Network (CISNet). Environ. Monit. Assess. 64(1):379-390. (ERL,GB 1076).

The U.S. Environmental Protection Agency (EPA), National Oceanic and Atmospheric Administration (NOAA), and National Aeronautics and Space Administration (NASA) have formed a partnership to establish pilot sites for the development of a network known as the Coastal Intensive Site Network (CISNet). CISNet is composed of intensive, long-term monitoring and research sites around the U.S. marine and Great Lakes coasts. In this partnership, EPA and NOAA are funding research and monitoring programs at pilot sites that utilize ecological indicators and investigate the ecological effects of environmental stressors. NASA is funding research aimed at developing a remote sensing capability that will augment or enhance in situ research and monitoring programs selected by EPA and NOAA. CISNet has three objectives: 1) to develop a sound scientific basis for understanding ecological responses to anthropogenic stresses in coastal environments, including the interaction of exposure, environment/climate, and biological/ecological factors in the response, and the spatial and temporal nature of these interactions, 2) to demonstrate the value of developing data from selected sites intensively monitored to examine the relationships between changes in environmental stressors, including anthropogenic and natural stresses, and ecological response, and 3) to provide intensively monitored sites for development and evaluation of indicators of change in coastal systems.

Summers, J. Kevin, Paul F. Kazyak and Stephen B. Weisberg. 1991. Water Quality Model for a River Receiving Paper Mill Effluents and Conventional Sewage. EPA/600/J-92/207. Ecol. Modell. 58(1-4):25-54. (ERL,GB 706). (Avail. from NTIS, Springfield, VA: PB92-195643)

During low flow periods in summer, portions of the Pigeon River, North Carolina, have experienced depressed dissolved oxygen concentrations. The Pigeon River receives multiple point source effluents from several wastewater treatment facilities and a large kraft paper mill located in Canton, NC which contribute the oxygen-demanding and nutrient loads to the river. A water quality model was constructed, from survey data specifically collected to meet the model's requirements, to examine the processes and sources contributing to the observed oxygen declines and to evaluate the specific management alternatives. The model was validated using two independent data sets. Simulations showed that relatively little of the CBOD materials released by the mill were degraded within the river and were subsequently 'deposited' in the reservoir at the end of the modeled river segment. Reductions in CBOD concentrations could be generally accounted for by tributary dilution. However, nitrogenous oxygen demanding materials released by the mill (e.g., NH3) created a considerable demand for oxygen within the modeled segment of the river. Model results showed this relatively rapid degradation of NBOD could depress oxygen levels to low levels (i.e., < 4 ppm) if artificial oxygenation was not used to supplement existing concentrations. The model also showed the majority of this oxygen supplement was released to the atmosphere and not maintained within the water column. Model analyses showed that the effluents associated with the wastewater treatment facilities had little effect on the water quality of the Pigeon River.

Summers, J. Kevin, Harold T. Wilson and Jingyee Kou. 1993. Method for Quantifying the Prediction Uncertainties Associated with Water Quality Models. EPA/600/J-93/226. Ecol. Modell. 65(3,4):161-176. (ERL,GB 741). (Avail. from NTIS, Springfield, VA: PB93-205094)

Many environmental regulatory agencies depend, to a large extent, upon the use of models to organize, understand, and utilize the information available for regulatory decision making. In light of the extensive use of environmental models, we developed a general analytical protocol to quantify the prediction error associated with commonly used suface water quality models. The methodology is designed in order to compare water quality models configured to represent different levels of spatial, temporal, and mechanistic complexity. This comparison can be accomplished by fitting the models to a benchmark data set. Once the models are successfully fitted to the benchmark data, the prediction errors associated with each application can be quantified using the Monte Carlo simulation techniques. The application of the protocol using these simulation techniques is described in a companion paper in which comparisons among model uncertainty results are made using the Wilcoxon ranked sum test to determine significant differences.

Summers, J. Kevin, Stephen B. Weisberg, A. Frederick Holland, Jingyee Kou, Virginia D. Engle, Denise L. Breitberg and Robert J. Diaz. 1997. Characterizing Dissolved Oxygen Conditions in Estuarine Environments. Environ. Monit. Assess. 45(3):319-328. (ERL,GB 743).

Dissolved oxygen concentration, which is often measured in estuaries to quantify the results of and stresses associated with eutrophication, can be highly variable with time of day and tidal stage. To assess how well dissolved oxygen conditions are characterized by typical monitoring programs, we conducted Monte Carlo sampling from 16 semi-continuous, 31-day dissolved oxygen records collected from estuaries along the Atlantic and Gulf coasts to mimic three sampling strategies: (1) systematic point-in-time sampling, (2) random point-in-time sampling, and (3) short-term continuous records. These strategies were evaluated for their accuracy in estimating mean oxygen concentration, minimum oxygen concentration, and percent of time below a threshold value of 2 ppm. Mean dissolved oxygen concentration was most accurately estimated in both estuarine regions by random point-in-time sampling, but this strategy required more than ten samplings per month for the estimate to be within 0.5 ppm on 50% of the simulations. Short-term continuous sampling (24-48h) correctly identified estuaries in the Gulf of Mexico region where dissolved oxygen concentration of less than 2 ppm were experienced greater than 20% of the time. However, large tidal variations in Atlantic coast estuaries showed this measure to be inaccurate in these estuarine environments. None of the sampling strategies correctly identified month-long oxygen minima within 0.5 ppm for more than 50% of the simulations. This inability to characterize correctly dissolved oxygen conditions could add significant uncertainty to risk assessments, waste load allocation models, and other water quality evaluations that are the basis for developing wastewater treatment strategies and requirements. Perhaps more importantly, the inaccuracy with which conventional sampling procedures characterize minimum dissolved oxygen values suggests that the extent of hypoxia in estuarine waters in being substantially underestimated.

Summers, J. Kevin and Virginia D. Engle. 1993. Evaluation of Sampling Strategies to Characterize Dissolved Oxygen Conditions in Northern Gulf of Mexico Estuaries. EPA/600/J-93/071. Environ. Monit. Assess. 24(3):219-229. (ERL,GB 745). (Avail. from NTIS, Springfield, VA: PB93-169050)

Dissolved oxygen was continuously monitored in eight sites of northern Gulf of Mexico estuaries in August, 1990. Monte Carlo analyses on subsamples of the data were used to evaluate several commonly used monitoring strategies. Monitoring strategies which involved single point sampling of dissolved oxygen may often misclassify an estuary as having good water quality. In the case of shallow, often well-mixed estuaries that experience diurnal cycles, such monitoring often does not occur at night, during the time of lowest dissolved oxygen concentration. Our objective was to determine the minimum sampling effort required to correctly classify a site in terms of the observed frequency of hypoxia. Tests concluded that the most successful classification strategy used the minimum dissolved oxygen concentration from a continuously sampled 24-hour period.

Summers, J. Kevin, John F. Paul and Andrew Robertson. 1995. Monitoring the Ecological Condition of Estuaries in the United States. EPA/600/J-96/071. Toxicol. Environ. Chem. 49(1-2):93-108. (ERL,GB 813).

The purpose of the Environmental Monitoring and Assessment Program/Estuaries component (EMAP-E) is to determine the current status, extent, changes, and trends in ecological indicators of the condition of the nation's estuarine resources on a regional and national basis. Monitoring activities in the Virginian (Mid-Atlantic) and Louisianian (Gulf of Mexico) Provinces focus on measurements that describe the benthic community, fish community, water quality, levels of sediment and tissue contamination, sediment toxicity, wetlands extent/condition, and seagrasses extent/condition. Estuarine monitoring is based on an EMAP-E probability-based sampling design conducted over a 60-day period during July-September of each year. Monitoring activities in the Virginian Province began in 1990 and have continued annually while monitoring in the Louisianian Province was initiated in 1991. The results of 1990 monitoring in the Virginian Province show that 20% of the sediments of the Mid-Atlantic region suffered from poor biological conditions while 15% of the area showed undesirable conditions in relation to poor water clarity and the presence of marine debris. In 1991, 31% of Gulf of Mexico estuarine sediments in the Louisianian Province displayed poor biological conditions, as measured by benthic community structure, and 32% of the area was characterized by poor water clarity, the presence of marine debris, and elevated levels of fish tissue contaminants. Efforts are presently underway to begin to assess degradation "causes" using statistical associations among exposure and stressor data for degraded areas in the two provinces. Monitoring will continue in these provinces as well as be initiated in the Great Lakes in 1992 and monitoring in other areas (Carolinian Province, Southeast) is scheduled to begin in 1994.

Summers, Kevin, Leroy Folmar and Miriam Rodon-Naveira. 1997. Development and Testing of Bioindicators for Monitoring the Condition of Estuarine Ecosystems. Environ. Monit. Assess. 47(3):275-301. (ERL,GB 921).

As part of the Environmental Monitoring and Assessment Program in 1991, the field efficacy of six "research" indicators was examined in the estuarine systems of the Gulf of Mexico. The utility of these indicators was tested by examining those responses at both ends of multiple environmental gradients; namely, under minimally impacted conditions (reference) and heavily impacted conditions (by hypoxia, industrial discharges, agricultural runoff). In addition, the geographic effects of location (east and west of the Mississippi River) were examined. Numbers and frequencies of pathologies, abundance of splenic macrophage aggregates, and vertebral abnormalities showed response patterns that suggest wider field testing along full gradients rather than simply the extremes of the gradient are warranted. Selected blood proteins showed some promise but logistical constraints in estuarine environments may limit its utililty. Concentrations of selected organic compounds in bile showed no differences in this study between references and contaminated sites. Molecular bioindicators are discussed with regard to their potential utility as indicators of ecosystem conditions. Of these potential indicators, the use of vitellogenin assays as a measure of reproductive impairment and frequency of shell disease in selected crustaceans as an indicator of immunological aberrations deserve further examination.

Summers, J. Kevin, Terry L. Wade, Virginia D. Engle and Ziad A. Malaeb. 1996. Normalization of Metal Concentrations in Estuarine Sediments from the Gulf of Mexico. Estuaries. 19(3):581-594. (ERL,GB 925).

Metal concentrations have been examined in sediments collected from 497 sites within the estuaries of the Gulf of Mexico by the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP). To isolate natural factors from anthropogenic ones, data were normalized for extant concentrations of aluminum. The normalization was based on the hypothesis that metals are anthropogenic. Strong linear correlations (>75% variation explained) were observed between Al and Cr, Cu, Pb, Ni, and Zn. Moderate correlations (50-75% variation explained) were observed between Al and As or Ag. Weak but significant correlations (30-40% variation explained) were observed between Al and Hg or Cd. Based on these results, the spatial extent of contamination has been examined, and it was found that about 39% of sites with contamination by at least one metal occurred near population centers, industrial discharge sites, or military bases. The remainder of the observed contamination represented a dispersed pattern, including the lower Mississippi River (7%) and numerous agricultural watersheds (54%), suggesting that the contamination might be from nonpoint sources.

Summers, J. Kevin, John M. Macauley and P. Thomas Heitmuller. 1991. Implementation Plan for Monitoring the Estuarine Waters of the Louisianian Province - 1991 Demonstration. EPA/600/5-91-288. U.S. Environmental Protection Agency, Environmental Research Laboratory, Gulf Breeze, FL. 160 p.

This document is an implementation plan for a Gulf Coast monitoring program supported by the U.S. Environmental Protection Agency. FY90-91 planning efforts are described for implementation of the Environmental Monitoring and Assessment Program (EMAP) in the coastal waters and estuaries of the northern Gulf of Mexico. The document details the design for sampling three classes of estuarine resources: (1) large estuaries (e.g., Apalachee Bay, Mobile Bay, Mississippi Sound, Lake Pontchartrain, Galveston Bay); large tidal rivers (i.e., Mississippi River); (3) small estuaries, bays, inlets, tidal creeks, and tidal rivers (e.g., Cedar Bayou, East Bay Bayou, Withlacoochie River, Little Lake Pelican Bay). Design modifications appropriate for representing the condition and trends in the extent and magnitude of ecological problems will be used when the Louisianian Province Program is implemented.

Summers, Kevin, Greg Steyer, Ed Decker, Philip Crocker, Flinda Hill, Gil McRae, Scott Brown, Jeff Thomas, Jim Simmons, David Brock, Carter Miska and Jimmy Johnston. 2000. Framework for an Integrated and Comprehensive Monitoring Plan for the Estuaries of the Gulf of Mexico. EPA/620/R-00/006.

Summers, Kevin, Gerald Pesch, Henry Walker, John Kiddon, James Harvey, Corey Garza, Virginia Engle, Lisa Smith, Linda Harwell, Walter Nelson, Henry Lee, Janet Lambertson, Barry Burgan, Darrell Brown and Jeff Bigler. 2004. National Coastal Condition Report II. EPA/620/R-03/002. U.S. Environmental Protection Agency, Office of Research and Development, Office of Water. Washington, DC 20460. Pp. 285.

Coastal waters in the United States include estuaries, coastal wetlands, coral reefs, mangrove and kelp forests, seagrass meadows, and upwelling areas. Critical coastal habitats provide spawning grounds, nurseries, shelter, and food for finfish, shellfish, birds, and other wildlife. The nation’s coastal resources also provide nesting, resting, feeding, and breeding habitat for 85% of waterfowl and other migratory birds. Estuaries are bodies of water that provide transition zones between the fresh water from rivers and the saline environment of the ocean. This interaction produces a unique environment that supports wildlife and fisheries and contributes substantially to the economy of the United States. Section 305(b) of the Clean Water Act requires that the U.S. Environmental Protection Agency (EPA) report periodically on the condition of the nation’s waters. As part of this process, coastal states provide valuable information about the condition of their coastal resources to EPA. However, because the individual states use a variety of approaches for data collection and evaluation, it is difficult to compare this information between states or on a national basis. To better address questions about national coastal condition, EPA, the National Oceanic and Atmospheric Administration (NOAA), the U.S. Department of the Interior (DOI), and the U.S. Department of Agriculture (USDA) agreed to participate in a multiagency effort to assess the condition of the nation’s coastal resources (U.S. EPA, 1998). The agencies chose to assess condition using nationally consistent monitoring surveys in order to minimize the problems created by compiling data collected using multiple approaches. The results of these assessments are compiled periodically into a National Coastal Condition Report. The first National Coastal Condition Report (NCCR I), published in 2001, reported that the nation’s estuarine resources were in fair condition. The NCCR I used available data from 1990 to 1996 to characterize about 70% of the nation’s estuarine resources. Agencies contributing these data included EPA, NOAA, the U.S. Fish and Wildlife Service (FWS), and USDA. This second National Coastal Condition Report (NCCR II) is based on available data from 1997 to 2000. These data are representative of 100% of estuarine acreage in the conterminous 48 states and Puerto Rico, and they show that the nation’s estuaries continue to be in fair condition. Agencies contributing data to this report include EPA, NOAA, FWS, and the U.S. Geological Survey (USGS). Several state, regional, and local organizations also provided information on the current condition of the nation’s coasts.

Summers, J. Kevin, John M. Macauley, P. Thomas Heitmuller, Virginia D. Engle, A. Matt Adams and Gary T. Brooks. 1993. Statistical Summary: EMAP-Estuaries Louisianian Province - 1991. EPA/620/R-93/007. U.S. Environmental Protection Agency, Environmental Research Laboratory, Gulf Breeze, FL. 101 p. (Avail. from NTIS, Springfield, VA: PB94-117488)

The Environmental Monitoring and Assessment Program (EMAP) is a joint effort of the Office of Modeling, Monitoring Systems, and Quality Assurance and the Office of Environmental Processess and Effects Research with the Office of Research and Development. EMAP is a long-term interagency commitment to monitor the ecological condition of the nation's ecological resources. An important step in implementing EMAP involves conducting regional demonstrations projects. This document, the 1991 Statistical Summary of the Louisianian Province, was the first statistical summary of a year's EMAP-Estuaries monitoring data. The 1991 project involved 202 sampling locations throughout the estuaries of the Gulf of Mexico. The preliminary assessment of estuarine conditions in the Louisianian Province identified differences in the degree of degradation among estuarine types throughout the province.

Summers, J. Kevin, John M. Macauley, Virginia D. Engle, Gary T. Brooks, P. Thomas Heitmuller and A. Matt Adams. 1993. Louisianian Province Demonstration Report EMAP-Estuaries: 1991. EPA/620/R-94/001. U.S. Environmental Protection Agency, Environmental Research Laboratory, Gulf Breeze, FL. 161 p.

This report summarizes the Louisianian Demonstration Project conducted by the Estuaries Resource Group of the Environmental Monitoring and Assessment Program (EMAP), a national program initiated by EPA to integrate efforts of governmental agencies in evaluations of status and trends of ecological resources of the U.S. The Louisianian Province represents a single biogeographic area corresponding to the Gulf of Mexico. The demonstration project was conducted during July and August 1991, using a probability-based sampling design to evaluate the condition of Gulf of Mexico estuarine resources. The assessment is preliminary and its findings should be confirmed by subsequent years of sampling in the Louisianian Province, which extends from Rio Grande, Texas, to Anclote Anchorage, Florida.

Summers, Kevin. 2004. Pollution and Ecosystem Health - Assessing Ecological Condition of Coastal Ecosystems. Presented at the White Water to Blue Water (WW2BW) Miami Conference, 21-26 March 2004, Miami, FL. 1 p. (ERL,GB R973).

Throughout the coastal regions and Large Marine Ecosystems (LMEs) of the United States, Mexico, Central America and the Greater Caribbean, pollution continues to be a major cause of the degradation of the condition of our coastal resources. While some methods and approaches exist to evaluate the "health" of a specific location, few of these methods can be adapted to examine "health" or condition at larger scales such as regions or nations. The development of survey designs, credible indicators, and analytical methods that provide an ability to evaluate coastal condition at the state, regional and national level, simultaneously, are needed to address legislative mandates, assess the success of environmental policies and protect coastal ecosystems. Coupling inshore assessments of condition with offshore assessment of fisheries resources addresses an overall objective of sustainable health rather than addressing site-specific local environmental problems without examining the effect of the change on adjacent ecosystems. To provides these large-scale assessments, indicators and indices must be developed to represent the condition of biota (plankton, benthos, fish) and their relationships with human-induced stresses (contamination, eutrophication, habitat destruction, overfishing). The development of a flexible, yet comprehensive and consistent, evaluative approach to condition assessment that could be applied throughout the coastal ecosystem of the US, Mexico, Central America and the Greater Caribbean would provide the tools necessary to determine the causes of degradation and assist in the protection of vital coastal ecosystems.

Summers, J. Kevin, William A. Richkus, C. Foster Stroup and Louis J. Rugolo. 1990. Influence of Natural and Anthropogenic Environmental Change on White Perch Stock Status in the Choptank River, Maryland. Fish. Res. 9(3):255-268. (ERL,GB X752).

A categorical time series regression model was developed to evaluate the importance of natural and anthropogenic environmental changes to the determination of white perch stock abundance in the Choptank River, Maryland. Ninety-one percent of the variability in historical stock size for the period 1929-1985 could be explained by a combination of April and May freshwater discharge level, parental stock size, and sewage loadings lagged 2-3 and 9-10 years. Clearly most of the annual variablity was associated with changes in natural environmental factors, but a significant, albeit, small portion of the variability in stock size was attributable to sewage loadings in the Choptank River.

Summers, J. Kevin. 1989. Simulating the Indirect Effects of Power Plant Entrainment Losses on an Estuarine Ecosystem. Ecol. Modell. 49:31-47. (ERL,GB X755).

Entrainment caused by the operation of the Chalk Point Steam Electric Station has been shown to be a major source of mortality to the early life stages of forage fish populations in the Patuxent River, MD, USA. While direct losses to these populations are important as a source of reduction for population abundance, these losses also represent decreases in estuarine forage supplies and potential reductions in the abundances of estuarine predators. A simple estuarine trophic dynamics model was constructed to determine the magnitude of the potential losses to major estuarine consumers in the Patuxent River ecosytem due to the power plant-related losses of forage fish. Simulations were completed using two sets of feeding assumptions: feeding proportional to forage abundance, and feeding based on dietary preferences. The model demonstrates that striped bass, bluefish, and weakfish could experience significant losses (greater than 25%) to overall population production levels if they prefer to prey upon bay anchovy and silversides and entrainment losses to these forage populations is greater than or equal to 70% of juvenile recruitment. The model also shows that indirect predator losses would be expected to be low (less than 5) if the majority of their diets consisted of forage other than bay anchovy and silversides.

Summers, J.K., C.F. Stroup and W.A. Richkus. 1990. Relationships Between Historical Hydrographic Conditions, Pollutant Loadings, and Fish Stocks in the Choptank and Rappahannock Estuaries. Maryland Department of Natural Resources, Annapolis, MD. 181 p. (ERL,GB X756).

Categorical time series regression models were developed to evaluate the importance of natural and anthropogenic environmental changes to the determination of fish stock status in the Choptank and Rappahannock estuaries. Time series from 1929-1988 for the commercial landings of six species and associated fishing effort were reconstructed for the two river basins. Relative catch-per-unit effort (CPUE) was determined and used as an indicator of stock size. Hydrographic data concerning freshwater discharge, temperature, precipitation, and wind speed and direction were collected, and time series were constructed to establish relationships between the variability in stock abundance and climatic variation. Time series for the same period were developed for indices representing pollutant loadings, developmental activities, and habitat alterations for the two targeted river basins. These indices included representations of demography, sewage and industrial loadings, habitat factors, and nutrient, carbon, and suspended sediment inputs. The compilation of these data is the result of intensive data collection efforts using county, state, and federal records to ascertain activities along individual water basins through time. Direct measures of loadings were used when available, and indirect indicators of loadings using materials-balance approaches were utilized where appropriate. Results of model regressions indicate that variation in the natural environment explains most of the variation in relative stock levels for most of the target species in the two Chesapeake Bay tributaries. The inclusion of significant natural variables in the models is generally consistent with existing knowledge on species biology. Pollutant variables such as pesticides, two heavy metals, PCBs, and nitrogen also contributed significantly to explaining observed variation in relative stock abundance of several species in both river systems. Further investigation is required to establish whether cause and effect relationships between pollutant loadings and stock levels may exist.

The U.S. Environmental Protection Agency (EPA) Environmental Monitoring and Assessment Program-Estuaries and the National Oceanic and Atmospheric Administration Bioeffects Surveys provide large datasets with which to test proposed relationships between sediment chemistry and toxicity. We conclude that guidelines based on bulk chemistry can provide useful triggers to further analysis but should not be used alone as indicators of toxicity. The sediment quality criteria for nonionic organic compounds proposed by the EPA are exceeded in so few samples that they may be of limited practical value. Toxicity was present in many cases when acid- volatile sulfide (AVS) concentrations exceeded the sum of concentrations of sulfide- insoluble metals. However, there is no way to test whether that toxicity was due to those trace elements. The AVS criterion is much more sensitive to AVS concentration than to trace metal contamination.

Rakocinski, Chet F., Steven S. Brown, Gary R. Gaston, Richard W. Heard, William W. Walker and J. Kevin Summers. 2000. Species-Abundance-Biomass Responses by Estuarine Macrobenthos to Sediment Chemical Contamination. J. Aquat. Ecosyst. Stress Recovery. 7(3):201-214. (ERL,GB 1053).

Macrobenthic community responses can be measured through concerted changes in univariate metrics, including species richness, total abundance, and total biomass. The classic model of pollution effects on marine macroinvertebrate communities recognizes that species/abundance/biomass (SAB) curves vary distinctively in a nonlinear manner with the magnitude of organic enrichment. For example, at moderate levels of organic enrichment, small-bodied opportunistic species boost the abundance curve, while species richness falls. Ratios among the metrics form useful indicators of how the community changes with organic enrichment. However, the classic SAB model is based on organic enrichment effects over small spatial and temporal scales, and the applicability of the SAB model to sediment chemical contamination and across broad natural estuarine gradients is largely unknown. Here, SAB responses were examined with respect to primary gradients in metals and organic chemicals based on an extensive dataset comprising 319 estuarine sites from throughout the northern Gulf of Mexico. Each SAB metric was first adjusted with respect to the three primary natural estuarine gradients, salinity, depth, and sediment silt/clay content. Adjusted SAB relationships varied in their details with respect to different classes of sediment contamination, but all types of SAB stress responses appear to exhibit similar basic characteristics. As in the SAB model, all three SAB metrics were notably low at the highest concentrations of both metal and organic-chemical contaminants. Moreover, rapid decreases in the B/A ratio with increasing contamination supported the concept that relatively long-lived, large-bodied, equilibrium taxa decline markedly at high concentrations of toxicants.

Engle, Virginia D. and J. Kevin Summers. 2000. Biogeography of Benthic Macroinvertebrates in Estuaries Along the Gulf of Mexico and Western Atlantic Coasts. EPA/600/J-00/4000. Hydrobiologia. 436(1-3):17-33. (ERL,GB 1067).

The community composition of benthic macroinvertebrates from 870 estuarine sites was examimed in order to either confirm or challenge established boundaries of biogeographical provinces along the Gulf of Mexico and western Atlantic coasts of the United States. The objective was two-fold: 1) to demarcate boundaries that separate dissimilar fauna in the Gulf of Mexico, and 2) to compare the Gulf of Mexico biogeographically with other well-known provinces. We segmented the coastline into grid cells with dimensions of 1° latitude and 2 to 4° longitude. Using the descriptive techniques of cluster analysis and nonmetric multidimensional scaling, we determined the similarities in benthic community composition between sites within grid cells in the Gulf of Mexico and compared the biotic ordinations to natural habitat characteristics such as salinity, sediment type, and depth. We then evaluated the overall community composition within each grid cell in the Gulf of Mexico and established whether or not similarities existed between adjacent grid cells. In this manner, we confirmed that an east-west gradient existed in estuarine benthic community composition along the Gulf of Mexico coast. This information was combined with our previous work in the western Atlantic coast to discern biogeographical provinces. Based on cluster analyses and an analysis of endemic benthic species the following provinces are proposed: (1) the Virginian province, from Cape Cod, Massachusetts to Wilmington, North Carolina, (2) the Gulf of Mexico, from Rio Grande, Texas to Cape Romano, Florida, and (3) south Florida, south of latitude 26°N. The region encompassing South Carolina, Georgia, and northern Florida represents a transitional area between temperate and tropical provinces.

Strobel, Charles J., John F. Paul, Melissa M. Hughes, Henry W. Buffum, Barbara S. Brown and J. Kevin Summers. 2000. Using Information on Spatial Variability of Small Estuaries in Designing Large-Scale Estuarine Monitoring Programs. Environ. Monit. Assess. 63(1):223-236. (ERL,GB 1075).

In the early 1990s, EPA's Environmental Monitoring and Assessment Program (EMAP) documented the ecological condition of the overall population of small estuaries along the Mid-Atlantic coast of the United States. However, the Program did not provide information on the condition of individual estuaries less than 260 km2 in surface area, a group of estuaries of concern to environmental managers. To address the needs of environmental managers, when EMAP returned to the region in summer 1997, it included a study of the spatial variability of ecology indicators within individual small estuaries. At 127 probability-based sites in 10 estuaries, EMAP measured a variety of parameters of water quality and sediments, including dissolved oxygen (DO), nutrients, grain size of sediments, contaminants in sediments, and community structures of benthic macroinvertebrates. From this information the ecological condition (e.g., percent area with DO concentrations below 5 mg L-1 for each estuary, along with 90% confidence interval, was determined. The width of the confidence intervals were then recalculated for sample sizes ranging from two stations to the total number of stations sampled in that estuary. Confidence interval widths were then plotted against sample size. These plots can be useful in designing future regional monitoring programs with a goal of describing conditions in individual systems as well as broad geographic regions. They illustrate that beyond five stations per estuary, the reduction in the width of the confidence interval with increasing sampling intensity is relatively small; however, individual program managers need to determine "how small is small enough".

Fournie, John W., J. Kevin Summers, Lee A. Courtney, Virginia D. Engle and Vicki S. Blazer. 2001. Utility of Splenic Macrophage Aggregates as an Indicator of Fish Exposure to Degraded Environments. J. Aquat. Anim. Health. 13(2):105-116. (ERL,GB 1105).

The utility of splenic macrophage aggregates (MAs) as an indicator of fish exposure to degraded environments was evaluated in several species of estuarine fishes as part of the Environmental Protection Agency's Environmental Monitoring and Assessment Program - Estuaries (EMAP-E). Using image analysis, the number and mean size of MAs/mm2 were measured on tissue sections of spleen from a total of 983 fishes representing 7 species from 266 stations scattered across the Gulf of Mexico coastal estuaries. These samples were analyzed for MAs and at 16 stations at least one fish exhibited high densities (>40 MAs/mm2 ). Densities of MAs that exceeded 40/mm2 correlated with exposure to either hypoxic conditions or sediment contamination. Fisher's exact test showed observed frequencies of joint occurrence between high numbers of MAs and both high sediment contaminants and low dissolved oxygen were higher than the expected background frequencies. For all 16 sites where MAs >40/mm2, sediments displayed at least one contaminant at a concentration in the highest 5% of those observed for all Gulf of Mexico stations. This study demonstrates that splenic MAs are effective biotic indicators that can be used to discriminate between fish exposed to degraded and non-degraded environments.

Steevens, Jeffery A., J. Kevin Summers and William H. Benson. 2001. Assessing Stressors in Coastal Ecosystems: An Approach to the Patient. Hum. Ecol. Risk Assess. 7(5):1447-1455. (ERL,GB 1116).

Medicine employs an approach to diagnose, give a prognosis, and develop a treatment for human patients. Specific signs and symptoms determined from medical examinations, laboratory tests, and patient history are utilized to predict the outcome of a potential pathological disorder. Utilizing a strategy similar to the medical examination, the status of ecosystems can be examined. To demonstrate this concept a "patient" case study of the Gulf of Mexico is described. The diagnosis of potential abnormalities within the Gulf of Mexico was conducted by examining field indicators including sediment chemistry and tissue chemistry (field examinations), sediment toxicity (laboratory testing), and a benthic index (patient history and existing symptoms). Based on the diagnosis (ecological assessment), a prognosis for the Gulf of Mexico was determined and specific areas that are impacted by stressors were identified for more detailed assessments. Pensacola Bay was identified as such an area impacted by stressors. The case study example demonstrates that a medical approach of "diagnosis and prognosis" can be utilized as a strategy to help identify stressors, develop a successful treatment plan, and prevent future ecosystem degradation.

Santavy, Deborah L., J. Kevin Summers, Virginia D. Engle and Linda C. Harwell. 2005. Condition of Coral Reefs in South Florida (2000) Using Coral Disease and Bleaching as Indicators. Environ. Monit. Assess. 100(1-3):129-152. (ERL,GB 1148).

The destruction of coral reef habitats has occurred at unprecedented levels during the last three decades. Coral disease and bleaching in the Caribbean and South Florida have caused extensive coral mortality with limited recovery, often coral reefs are being replaced with turf algae. Acroporids were once dominant corals and have diminished to the state where they are being considered as endangered species. Our survey assessed the condition of reef corals throughout South Florida. A probability-based design produced unbiased estimates of the spatial extent of ecological condition, measured as the absence or presence and frequency or prevalence of coral diseases and bleaching intensity over large geographic regions. This approach allowed us to calculate a quantifiable level of uncertainty. Coral condition was estimated for 4100 hectares (ha) (or 41.0 km2) of coral reefs in South Florida, including reefs in the Florida Keys National Marine Sanctuary (FKNMS), New Grounds, Dry Tortugas National Park (DTNP), and Biscayne National Park (BNP). The absence or presence of coral disease, "causal" coral bleaching, partial bleaching and coral paling were not good indicators of overall coral condition. It was more useful to report the prevalence of anomalies that indicated a comprised condition at both the population and community levels. For example, 79% of the area in South Florida had less than 6% of the coral colonies diseased, whereas only 2.2% (97.15 ha) of the sampled area had a maximum prevalence of 13% diseased coral colonies at any single location. The usefulness of "causal bleaching" might be more important when considering the prevalence of each of the three different states at a single location. For example, paling was observed over the entire area, whereas bleaching and partial bleaching occurred at 19 and 41% of the area, respectively. An index for coral reef condition might integrate the prevalence and species affected by each bleaching state at individual locations. By establishing these baselines, future surveys can examine changes and trends in the spatial distribution of coral conditions in South Florida and able to score the reefs as to their health status.

DiDonato, Guy T., J. Kevin Summers and Thomas H. Roush. 2003. Assessing the Ecological Condition of a Coastal Plain Watershed Using a Probabilistic Survey Design. Environ. Monit. Assess. 85(1):1-21. (ERL,GB 1157).

Using a probabilistic survey design, we assessed the ecological condition of the Florida (U.S.A.) portion of the Escambia Riverwatershed using selected environmental and benthic macroinvertebrate data. Macroinvertebrates were sampled at 28 sites during July-August 1996, and 3414 individuals were identified. Taxonomic data were distilled into the 8 m of the Stream Condition Index (SCI), developed specifically for Florida waterways, and sites were classified on an ordinal scale as very good, good, poor, and very poor. The weighted cumulative distribution function of the SCI showed that 8% (± 7) of the stream and river miles in this landscape were in very good condition, while 25% (± 7), 51% (± 16), and 16%(±15) were in good, poor, and very poor condition, respectively.The only environmental parameter significantly correlated with SCI was dissolved oxygen (DO), and two sites classified as very poor had oxygen levels around or below 2 mg L-1. However, other sites exhibited similarly low SCI values without the attendant low DO, implying that factors determining site condition were complex and multivariate. The results of this survey corroborate Federal and state assessments demonstrating that many locations within this watershed exhibit significant degradation.

Smith, Lisa M., Virginia D. Engle and J. Kevin Summers. 2006. Assessing Water Clarity as a Component of Water Quality in Gulf of Mexico Estuaries. Environ. Monit. Assess. 115(1-3):291-305. (ERL,GB 1216).

The U.S. Environmental Protection Agency Environmental Monitoring and Assessment Program (EMAP) uses water clarity as a water quality indicator for integrated assessments. After the publication of the first National Coastal Condition Report, the national water clarity reference value of 10% of ambient surface light at 1 meter depth was reevaluated and modified to reflect expected differences in regional light conditions. These regional differences range from naturally turbid estuaries like those found in Mississippi and Louisiana areas to clear water estuaries expected to support extensive beds of submerged aquatic vegetation in, for example, Florida and Tampa Bays. For the second National Coastal Condition Report, water clarity was assessed based on regional reference values. Not all states collected light meter data at 1 m; however, all states reported secchi depth. Different regional water clarity reference values and data collection methods necessitated the development of a water clarity index based on light attenuation coefficients (k). This index incorporates regional reference conditions and is interchangeable with secchi depth and percent light transmission calculated from light meter measurements. Evaluation of the water clarity index shows that k values based on transmissivity at 1 m can be estimated from secchi depth measurements and successfully used as a surrogate for transmissivity calculated from light meter data. An approach for assessing water clarity in Gulf of Mexico estuaries using light meter data and secchi depth is presented.

Smith, Lisa M., Eva M. Didonato, Linda C. Harwell, Janet A. Nestlerode and J. Kevin Summers. 2007. The Ecological Condition of Gulf of Mexico Resources from Perdido Key to Port St. Joe, Florida, USA: Part I Coastal Beach Resources. Environ. Monit. Assess. 128(1-3):511-524. (ERL,GB 1248).

Using the approach established by EPA’s Environmental Monitoring and Assessment Program (EMAP), a shoreline monitoring survey was conducted in August and September 1999, encompassing the Florida Panhandle from Perdido Key, Florida to Port St. Joe, Florida. The objective of this multi-tiered survey was to evaluate the use of a probabilistic survey for monitoring and estimating the condition of swimmable beach areas. Thirty stations were sampled using a probablistic sampling design. Hydrographic data were collected in addition to samples for water chemistry. Bacterial indicators, enterococci and fecal coliforms, were enumerated from the water according to the EPA Beaches Environmental Assessment Closure and Health (BEACH) Program and Florida state guidelines. Additional criteria for site condition included the presence or absence of primary and secondary dunes, anthropogenic debris and vegetation. Based on EMAP evaluation guidelines and Florida state criteria, a baseline assessment of the condition of the Gulf of Mexico beach resources surveyed is presented.

Smith, Lisa M., James E. Harvey, Linda C. Harwell and J. Kevin Summers. 2007. The Ecological Condition of Gulf of Mexico Resources from Perdido Key to Port St. Joe, Florida: Part II Near-Shelf Coastal Resources. Environ. Monit. Assess. 127(1-3):189-207. (ERL,GB 1255).

In 1999, the United States Environmental Protection Agency Gulf Ecology Division initiated a pilot study to assess the condition of nearshore coastal resources. Near-shelf areas associated with coastal beaches are susceptible to land based activities, but are not consistently monitored. Additionally, few or no marine water quality criteria exist for evaluating these waters. The goal of this pilot study was to evaluate a probability based sampling design for assessing the Gulf of Mexico near-shelf resources using indicators for water quality, sediment quality, and biological condition. Baseline data can be used to assess coastal nearshore areas and provide a comparative tool for evaluating future trends in condition. Water quality, sediment quality and benthic diversity data can provide a baseline assessment for managers to evaluate the potential for future problems such as nutrient over-enrichment, sediment contamination and biological condition. We present the use of a probability based survey design to assess near-shelf resources along the Florida Panhandle.

Harvey, James, Linda Harwell and J. Kevin Summers. 2008. Contaminant Concentrations in Whole-Body Fish and Shellfish from U.S. Estuaries. Env. Monit. Assess. 137(1-3):403-412. (ERL,GB 1274).

Persistent bioaccumulative and toxic (PBT) pollutants are chemical contaminants that pose risks to ecosystems and human health. For these reasons, available tissue contaminant data from the US EPA Environmental Monitoring and Assessment Program’s National Coastal Assessment were examined to estimate to what areal extent PBTs are found in US estuarine resources. The data document composite, whole-body tissue chemical concentrations for 736 sampling sites across Northeast, Southeast, Gulf of Mexico, and West Coast estuaries. Tissue chemical concentrations were compared to US EPA non-cancer risk guidelines for recreational fishers, because of a lack of ecological guidelines for these chemical concentrations. Samples were analyzed for 23 PAR compounds, 21 PCB congeners, 6 DDT derivatives and metabolites, 14 chlorinated pesticides (other than DDT) and 13 metals, including mercury. Total PCBs were found to exceed recreational fisher guidelines most frequently (31% of samples evaluated), followed by mercury (29%), total PAHs (2 1%), and DDT and its metabolites, DDD and DDE (11%). Toxaphene, cadmium and dieldrin were found but in fewer than 1% of the samples.

DiDonato, Eva M., Guy T. DiDonato, Lisa M. Smith, Linda C. Harwell, Virginia D. Engle and J. Kevin Summers. Accepted. Using the National Coastal Assessment Methodology to Evaluate the Water, Sediment, and Fish Tissue Quality of American Samoa's Near-Shore Marine Resources. National Park Service. 22p. (ERL,GB 1303). (technical report series)

DiDonato, Guy T., Eva M. DiDonato, Lisa M. Smith, Linda C. Harwell and J. Kevin Summers. 2009. Assessing Coastal Waters of American Samoa: Territory-Wide Water Quality Data Provide a Critical "Big-Picture View" for this Tropical Archipelago. Environ. Monit. Assess. 150(1-4):157-165. (ERL,GB 1311).

The coastal waters of American Samoa’s 5 high islands (Tutuila, Aunu’u, Ofli, Olosega, and Ta’u) were surveyed in 2004 using a probabilistic design. Water quality data were collected from the near-shore coastal habitat, defined as all near-shore coastal waters including embayments, extending out to 1/4 mile off-shore. Hydrography and water column nutrient samples were collected, and water quality data were compared to the 2005 Territorial water quality standards for PH, dissolved oxygen (DO), Enterococcus chlorophyll a, water clarity, total nitrogen, and total phosphorus. All station measurements for pH, DO, and Enterococcus satisfied the local water quality standards, although some fraction of the Territory could not be assessed for either DO or Enterococcus. With respect to the chlorophyll a standard, 66 ± 18% of the Territory complied with the standard, while 34± 18% failed to comply with the standard. For water clarity, 54 ± 18% of the Territorial waters complied with the standard while 42 ± 7% failed to comply. Territorial waters satisfied the standards for total nitrogen and phosphorus 72 ± 17% and 92 ± 10%, respectively. These data provide the first “big picture” view of water quality in the near shore region around the high islands of American Samoa. While the picture is encouraging, especially in light of the rapidly growing population and increasing development on Tutuila, these data suggest emerging water quality issues.

Lores, Emile M., James M. Patrick and J. Kevin Summers. 1993. Humic Acid Effects on Uptake of Hexachlorobenzene and Hexachlorobiphenyl by Sheepshead Minnows in Static Sediment/Water Systems. EPA/600/J-93/215. Environ. Toxicol. Chem. 12(3):541-550. (ERL,GB 746). (Avail. from NTIS, Springfield, VA: PB93-204980)

The effect of humic acid on accumulation of hexachlorobenzene (HCB) and hexachlorobiphenyl (HCBP) by sheepshead minnows (Cyprinodon variegatus) from two separate experiments is presented. In the first experiment, static sediment/water exposure chambers were used to determine the effect of dissolved organic carbon (DOC), in the form of terrestrial humic acid (HA), on partitioning of HCB among sediment, water, and sheepshead minnows. Sediments from three geographically different locations were used to test the effect of added HA (0, 3, and 30 mg/L) on accumulation in fish of sediment-bound HCB. Total organic carbon levels in sediment and water and residues of HCB (14 C-labeled and unlabeled) in sediment, water, and whole-body tissue were measured. Fish/sediment ratios or accumulation relative to sediment (ARS) indicated that addition of HA did not reduce accumulation of sediment-bound toxicants. ARS ranged from 7.5 + or - 4 without added HA to 9.3 + or - 4 with 30 mg/L added HA, but were not statistically different. In a second experiment using HCBP with 0 and 30 mg/L HA and sediment from one location, HCBP concentration in water averaged 0.29 µg/L in non-HA tanks and 0.91 µg/L in the HA tanks, but both ARS ratios averaged 5.4. In conclusion, we believe that these tests indicate that HA does not significantly alter bioavailability of toxicants that are in equilibrium with sediment and water.

Rose, Kenneth A. and J. Kevin Summers. 1992. Relationships Among Long-Term Fisheries Abundances, Hydrographic Variables, and Gross Pollution Indicators in Northeastern U.S. Estuaries. Fish. Oceanogr. 1(4):281-293. (ERL,GB 781).

Categorical time series regression was applied to 55 fish stocks in the Potomac, Hudson, Narragansett, Delaware, and Connecticut estuaries for the period 1929-1975. Interannual variability in catch per unit effort (CPUE) was related to CPUE, hydrographic variables, and pollution variables, lagged back in time to represent the conditions contributing to the multiple ages comprising each fishery. Hydrographic variables included water temperature and flow in the estuary--and, for offshore spawning stocks, wind direction and magnitude--during the months of spawning and early life stage development. Pollution variables included measures of dissolved oxygen conditions int he estuaries, volume of material dredged, and sewage loading (or human population). Lagged CPUE, hydrographic variables, and pollution variables all played important roles in explaining historical variability in CPUE. Lagged CPUE was significant in 45 of 55 stocks generally accounting for 5-35% of the variability. Lagged hydrographic variables were significant in 53 of 55 stocks, explaining an additional 5-40% of the variability unaccounted for by lagged CPUE. Lagged pollution variables were significant in 35-55 stocks, generally accounting for an additional 5-30% of the variability not explained by lagged CPUE and hydrographic variables. Results did not exhibit expected patterns of consistency in the importance of lagged CPUE for a species across estuaries or consistency in the importance of pollution variables across estuaries. Results did exhibit the expected north-to-south longitudinal pattern in the importance of timing of the hydrographic variables, the months of importance being none or two months later in more northerly estuaries. Higher-order interaction effects were important in almost all stocks that were well-modeled by categorical time series regression. Of the 30 stocks with final regression models having R2 > 0.55, 26 stocks involved significant interaction effects, five had only significant interaction effects (no significant main effects), and 20 stocks had significant interactions involving variables not significant as main effects. The difficulties involved in analyzing long-term trends in fish populations and partitioning variability between natural and anthropogenic sources are discussed.

Engle, Virginia D., J. Kevin Summers and Gary R. Gaston. 1994. Benthic Index of Environmental Condition of Gulf of Mexico Estuaries. Estuaries. 17(2):372-384. (ERL,GB 823).

An index was developed for estuarine macrobenthos in the Gulf of Mexico that discriminated between areas with degraded environmental conditions and areas with undegraded or reference conditions. Test sites were identified as degraded or reference based on criteria for dissolved oxygen levels, sediment toxicity tests, and sediment contamination. Discriminant analysis was used to identify a suite of measures of benthic community composition and diversity that would most successfully distinguish degraded from undegraded sites. The resultant benthic index was composed of a linear combination of three factors: the Shannon-Wiener diversity index, the proportion of total benthic abundance as tubificid oligochaetes, and the proportion of total benthic abundance as bivalve molluscs. This index was used to evaluate the spatial patterns of degraded benthic resources in the Gulf of Mexico.

Fournie, John W., J. Kevin Summers and Stephen B. Weisberg. 1996. Prevalence of Gross Pathological Abnormalities in Estuarine Fishes. Trans. Am. Fish. Soc. 125(4):581-590. (ERL,GB 942).

Gross external pathological abnormalities are frequently used as indicators of anthropogenic influence in estuarine and marine waters, but little baseline information is available to identify what constitutes normal prevalences (percentages of animals affected). To establish this baseline, trawl samples were collected from 120 randomly located estuarine sites in the Virginian biogeographic province (mid-Atlantic) in 1990 and from 220 randomly located sites in the Louisianian biogeographic province (Gulf Coast) in 1991 and 1992. Sediment contaminant concentrations were measured at each site. In all, 24,291 fish representing 143 species were examined for gross pathological abnormalities, and background prevalences were estimated to be 0.5% in mid-Atlantic and 0.7% in Gulf Coast estuaries. Fifteen types of gross abnormalities were noted. Skin lesions were the most prevalent abnormalities in both provinces, followed by ocular abnormalities (e.g., exophthalmia, keratitis) in the Virginia Province and branchial chamber abnormalities (e.g., parasites, gill arch deformities) in the Louisianian Province. The prevalence of gross abnormalities was about three times higher for demersal fish than for pelagic fish and was about eight times more prevalent at sites with high sediment contaminant concentrations. Among the major estuarine systems of the mid-Atlantic and Gulf of Mexico coastlines pathological abnormalities were most prevalent in Galveston Bay and lowest in Long Island Sound and Mississippi Sound.

Engle, Virginia D., J. Kevin Summers and John M. Macauley. 1999. Dissolved Oxygen Conditions in Northern Gulf of Mexico Estuaries. Environ. Monit. Assess. 57(1):1-20. (ERL,GB 944).

Because deficient dissolved oxygen (DO) levels may have severe detrimental effects on estuarine and marine life, DO has been widely used as an indicator of ecological conditions by environmental monitoring programs. The U.S. EPA's Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) monitored DO conditions in the estuaries of the Gulf of Mexico from 1991 to 1994. DO was measured in two ways: 1) instantaneous profiles from the surface to the bottom were taken during the day, and 2) continuous measurements were taken near the bottom at 15 min intervals for at least 12 h. This information was summarized to assess the spatial distribution and severity of DO conditions in these estuaries. Depending on the criteria used to define hypoxia (DO concentrations usually <2 mg L-1 or <5 mg L-1) and the method by which DO is measured, we estimate that between 5.2 and 29.3% of the total estuarine area in the Louisianian Province was affected by low DO conditions.

Heimbuch, Douglas G., Harold T. Wilson and J. Kevin Summers. 1998. Design-Based Estimators and Power Analyses of Trend Tests for the Proportion of Fish That Exhibit Gross Pathological Disorders. Environ. Ecol. Stat. 5(1):65-80. (ERL,GB 947).

Methods for estimating the proportion of fish that exhibit gross pathological disorders and for estimating the variance of these estimates are defined. The methods are for the situation in which a probability-based sampling design is used to collect fish for examination, but geographic locations (rather than individual fish) are assigned probabilities of being selected for sampling. To illustrate the use of the methods, they are applied to data collected during the 1992 EMAP-Estuaries sampling program in the Louisianian Province (i.e., the Gulf of Mexico). Separate estimates of the proportion of fish with gross pathological disorders are computed for demersal species, commercial species, pelagic species, and all species as one group. In addition, a test for trend in the proportion of fish that exhibit gross pathological disorders is defined, and analyses of the power of the test are presented. The power analyses are based on a general underlying model of the random distribution patterns of fish and the random process of catching fish. The power analyses also take into account the features of the sampling designs used for collecting fish. Component parameter estimates were computed using data from the 1992 EMAP-Estuaries sampling program in the Louisianian Province. Results from these analyses suggest that the EMAP-Estuaries sampling designs are capable of detecting a 0.15% change per year in the proportion of fish (all species groups combined) with gross pathological disorders in estuaries of the Louisianian Province over a 12-year period with a power of at least 80%.

Engle, Virginia D. and J. Kevin Summers. 1999. Refinement, Validation, and Application of a Benthic Condition Index for Northern Gulf of Mexico Estuaries. Estuaries. 22(3A):624-635. (ERL,GB 988).

By applying discriminant analysis to benthic macroinvertebrate data to produce a benthic index, we have developed an indicator of benthic condition for northern Gulf of Mexico estuaries. The data used were collected by the U.S. Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program (EMAP) in the Louisianian Province from 1991 to 1994. This benthic index represents a linear combination of the following weighted parameters: the proportion of expected species diversity, the mean abundance of tubificid oligochaetes, the percent of total abundance represented by capitellid polychaetes, the percent of total abundance represented by bivalve mollusks, and the percent of total abundance represented by amphipods. We successfully validated and retrospectively applied the benthic index to all of the benthic data collected by EMAP in the Louisianian Province. This benthic index was also calculated for independent data collected from Pensacola Bay, Florida, in order to demonstrate its flexibility and applicability to different estuarine systems within the same biogeographic region. The benthic index is a useful and valid indicator of estuarine condition that is intended to provide environmental managers with a simple tool for assessing the health of benthic macroinvertebrate communities.

Rakocinski, Chet F., Steven S. Brown, Gary R. Gaston, Richard W. Heard, William W. Walker and J. Kevin Summers. 1997. Macrobenthic Responses to Natural and Contaminant-Related Gradients in Northern Gulf of Mexico Estuaries. Ecol. Appl. 7(4):1278-1298. (ERL,GB 995).

Effects of pollution on biotic integrity are difficult to identify when correlations occur between environmental gradients and contaminant effects, as they do in estuaries. In this broad-scale study, we used canonical correspondence analysis (CCA) to distinguish influences of natural and contaminant-related gradients on macrobenthic community structure among 319 sites from estuaries throughout the northern Gulf of Mexico. Natural gradients in salinity, depth, and sediment composition obscured the detection of macrobenthic responses to sediment contamination. After adjusting for natural environmental variability, however, partial CCA revealed important macrobenthic variation in relation to sediment contamination. A rotated principal component analysis (PCA) distinguished five composite environmental factors, each largely reflecting contaminant or natural variation. Two complex gradients in sediment contamination identified by the PCA diverged in partial CCA space and correlated with different macrobenthic indicator taxa. Contaminant gradients represented variation in two different classes of sediment contaminants: trace metals and organic chemicals. Dispersion patterns of CCA site coordinates enabled cross validation of implied contamination-related variation in community function and the utility of several interpretive or management metrics. Trophic diversity decreased with sediment contamination, linking shifts in macrobenthic community function and community structure along contaminant gradients. The CCA model complemented on earlier benthic index developed from these data to examine biotic integrity, but the benthic index could not discern macrobenthic responses to the different contaminant gradients. Neither was the benthic index useful for showing transitions in macrobenthic community structure commensurate with different levels of contamination. Ampelisca amphipod sediment bioassays were inadequate for identifying contaminant effects on biotic integrity, whereas Mysidopsis mysid sediment bioassays conservatively reflected sediment contamination and associated macrobenthic indicators.

Malaeb, Ziad A., J. Kevin Summers and Bruce H. Pugesek. 2000. Using Structural Equation Modeling to Investigate Relationships Among Ecological Variables. Environ. Ecol. Stat. 7:93-111. (ERL,GB 999).

Structural equation modeling is an advanced multivariate statistical process with which a researcher can construct theoretical concepts, test their measurement reliability, hypothesize and test a theory about their relationships, take into account measurement errors, and consider both direct and indirect effects of variables on one another. Latent variables are theoretical concepts that unite phenomena under a single term, e.g., ecosystem health, environmental condition, and pollution (Bollen, 1089). Latent variables are not measured directly but can be expressed in terms of one or more directly measurable variables called indicators. For some researchers, defining, constructing, and examining the validity of latent variables may be the end task of itself. For others, testing hypothesized relationships of latent variables may be of interest. We analyzed the correlation matrix of eleven environmental variables from the U.S. Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) using methods of structural equation modeling. We hypothesized and tested a conceptual model to characterize the interdependencies between four latent variables - sediment contamination, natural variability, biodiversity, and growth potential. In particular, we were interested in measuring the direct, indirect, and total effects of sediment contamination and natural variability on biodiversity and growth potential. The model fit the data well and accounted for 81% of the variability in biodiversity and 69% of the variability in growth potential. It revealed a positive total effect of natural variability on growth potential that otherwise would have been judged negative had we not considered indirect effects. That is, natural variability had a negative direct effect on growth potential of magnitude - 0.3251 and a positive indirect effect mediated through biodiversity of magnitude 0.4509, yielding a net positive total effect of 0.1258. Natural variability had a positive direct effect on biodiversity of magnitude 0.5347 and a negative indirect effect mediated through growth potential of magnitude - 0.1105 yielding a positive total effects of magnitude 0.4242. Sediment contamination had a negative direct effect on biodiversity of magnitude 0.1956 and a negative indirect effect on growth potential via biodiversity of magnitude - 0.067. Biodiversity had a positive effect on growth potential of magnitude 0.8432, and growth potential had a positive effect on biodiversity of magnitude 0.3398. The correlation between biodiversity and growth potential was estimated at 0.7658 and that between sediment contamination and natural variability at - 0.3769.

Macauley, John M., J. Kevin Summers, Virginia D. Engle, P. Thomas Heitmuller, Gary T. Brooks, Maureen Babikow and A. Matt Adams. 1994. Statistical Summary: EMAP-Estuaries Louisianian Province - 1992. EPA/620/R-94/002. U.S. Environmental Protection Agency, Environmental Research Laboratory, Gulf Breeze, FL. 80 p. (Avail. from NTIS, Springfield, VA: PB94-174752)

Regional demonstration projects are an integral part of the Environmental Monitoring and Assessment Program (EMAP), which is a joint effort of the Office of Modeling, Monitoring Systems, and Quality Assurance and the Office of Environmental Processes and Effects Research with the Office of Research and Development. EMAP is a long-term interagency commitment to monitor the ecological condition of the nation's ecological resources. The 1992 Statistical Summary of the Louisianian Province is the second annual statistical summary of EMAP-Estuaries monitoring data. The 1992 project involved 159 sampling locations throughout the estuaries of the Gulf of Mexico. The preliminary assessment of the second year data of estuarine conditions in the Louisianian Province continued to identify differences in the degree of degradation among estuarine types throughout the province.

Turner, R. Eugene, Erick M. Swenson and J. Kevin Summers. 1995. Coastal Wetlands Indicator Study: EMAP-Estuaries Louisianian Province - 1991. EPA/620/R-95/005. U.S. Environmental Protection Agency, Environmental Research Laboratory, Gulf Breeze, FL. 99 p.

This document describes the rationale, objectives, approach, and strategy for testing biological indicators of ecological condition in coastal wetlands. This coastal wetlands program is part of the Environmental Monitoring and Assessment Program (EMAP) administered by the Environmental Protection Agency's (EPA) Office of Research and Development. The overall goal of EMAP-Coastal Wetlands is to provide a quantitative assessment of the status and long-term trends in coastal wetland condition on regional and national scales with known confidence. The purpose of this report is to begin the process of indicator selection and testing to produce the appropriate field measurements, statistical metrics, and reporting indices to assess status or condition of coastal wetlands. The biological indicators to assess coastal wetland condition or 'health' is central to the EMAP concept. It assumes that meaningful information can be obtained for regional and national assessments of important coastal wetland attributes on a fairly constrained and limited set of indicator measurements. The development and selection of indicators for EMAP-Coastal Wetlands is viewed as a continual process, now in its early stages. This study examined the evaluation of 21 wetland indicators related to sediment characteristics, vegetation, and hydrology. The study focused on the quantification and evaluation of five endpoints with regard to these indicators: 1) Spatial and Temporal Variability, 2) Responsiveness, 3) Interpretability and Ambiguity, 4) Integration and 5) Cost Effectiveness.

Macauley, John M., J. Kevin Summers, Virginia D. Engle, P. Thomas Heitmuller and A. Matt Adams. 1995. Statistical Summary: EMAP-Estuaries Louisianian Province - 1993. EPA/620/R-96/003. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, Gulf Breeze, FL. 96 p. (Avail. from NTIS, Springfield, VA: PB97-149504)

This statistical summmary of the ecological condition of the estuarine resources is based on the results of the 1993 Louisianian Province Demonstration Project. The population of estuarine resources with the Louisianian Province consists of all estuarine areas located along the coastline of the Gulf of Mexico between, and including, the Rio Grande, Texas, and Anclote Anchorage, Florida. The Environmental Monitoring and Assessment Program (EMAP) is a national program initiated by EPA and integrating the efforts of several federal agencies to evaluate the status and trends of the ecological resources of the United States. EMAP-Estuaries (EMAP-E) is a part of EMAP organized to evaluate the status and trends of the estuarine resources of the United States. The Louisianian Province Demonstration Project was conducted during the summer of 1993 (July-August) using a probability-based sampling design to evaluate the condition of the estuarine resources in this geographic region. One hundred and fifty-four sites between Anclote Anchorage, Florida, and the Rio Grande, Texas, were sampled during the eight-week sampling period. A series of indicators that are representative of the overall condition of estuarine resources were measured at each site. These indicators were designed to address three major attributes of concern: 1) estuarine biotic integrity, 2) societal values related to public use of esturine resources, and 3) pollutant exposure, or the environmental conditions under which biota live.

Engle, Virginia D., John M. Macauley, J. Kevin Summers and Pete Bourgeois. 1999. Ecological Condition of Estuaries in the Gulf of Mexico. EPA/620/R-98/004. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, Gulf Breeze, FL. 71 p.

The Gulf of Mexico is a vast natural resource that encompasses the coastal areas of western Florida, Alabama, Mississippi, Louisiana and Texas, as well as a portion of Mexico. Many estuaries flow into the Gulf of Mexico and serve as nursery grounds for fish, habitat for a wide variety of wildlife including several endangered species, shipping routes, and a source of recreation for people. This report began as an overall summary of the activities of the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) in the estuaries of the Louisianian and West Indian provinces. One of EMAP's goals is to translate environmental monitoring data from multiple spatial and temporal scales into assessments of ecological conditions. From 1991 to 1995 EMAP collected data on ecological indicators from estuaries in the Gulf of Mexico. The ecological condition of these estuaries was assessed in annual statistical summaries that enumerated the percent area of estuaries that were found to have undesired conditions (e.g. low dissolved oxygen, degraded benthic habitat, or contaminated sediments). By producing this report on the ecological conditions of estuaries in the Gulf of Mexico, we have taken one step in establishing the status of this environmental resource. We have produced a "report card" for the condition of these estuaries to be used as a benchmark from which to evaluate future conditions. This effort required the cooperation of various federal agencies and the contributions of data and information from many federal and state agencies as well as private environmental groups.

DiDonato, Guy T., Thomas H. Roush, Virginia D. Engle and J. Kevin Summers. 2000. Condition Assessment for the Escambia River, FL, Watershed: Benthic Macroinvertebrate Surveys Using a Probabilistic Sampling Design. Presented at NABS 2000, 48th Annual Meeting of the North American Benthological Society, 28 May-1 June 2000, Keystone, CO. 1 p. (ERL,GB R724).

Probabilistic sampling has been used to assess the condition of estuarine ecosystems, and the use of this survey design approach was examined for a northwest Florida watershed. Twenty-eight lotic sites within the Escambia River, Florida, watershed were randomly selected and visited during July-August, 1996. Hydrologic and water chemistry were collected, and benthic macroinvertebrates were sampled using Hester-Dendy artificial substrate samplers deployed for 27-29 days. Macroinvertebrates were preserved and identified down to the lowest practical taxonomic level (usually Genus). A total of 3476 benthic invertebrates were identified, comprising 58 taxa and 28 families. The numerical dominants were the midges Tanytarsus and Tribelos (23.7% of the sampled animals) and oligochaetes (26.5%), although oligochaete numbers were strongly influenced by one particular site. Stenonema and Baetis were the most common mayflies and accounted for 7.9 and 1.4% of the total invertebrates, respectively, while caddisflies (genus Hydropsyche) composed 5.8% of the identified fauna. These data were summarized using common metrics, including number of taxa, number of EPT taxa, and the Shannon-Weiner diversity index, to assess stream condition with a Stream Condition Index (SCI) developed for Florida.

McLean, Richard I. and J. Kevin Summers. 1990. Evaluation of Transport and Storage of 60Co, 134Cs, 137Cs and 65Zn by River Sediments in the Lower Susquehanna River. Environ. Pollut. 63:137-153. (ERL,GB X753).

The Peach Bottom Atomic Power Station (PBAPS) has contributed measurable quantities of radioactivity to Conowingo Reservoir, an impoundment of the lower Susquehanna River. As part of an ongoing radiological assessment program, concentrations of plant-related radionuclides in sediments have been monitored in spring and fall since 1980. Mass balance estimates derived from grab samples of surface sediments (less than 10 cm) indicate that less than 20% of reactor relased 60Co, 65Zn, 134Cs and 137Cs is present in these sediments. Significant seasonal variations in radionuclide trapping efficiency by the reservoir are not apparent. Deep core samples (c.200 cm) confirm that some, but not all, of this surface sediment radionuclide inventory remains within the reservoir--trapped in discrete locations by subsequent sediment accumulation. The remaining radionuclide mass, in dissolved or particle-associated form, appears to be transported downstream, through Conowingo Dam, to upper Chesapeake Bay. The detection of PBAPS-derived radionuclides in the sediments of upper Chesapeake Bay, primarily the Susquehanna Flats, confirms the transport of these radionuclides from the lower Susquehanna River.

Paul, John F., A.F. Holland, Steven C. Schimmel, J. Kevin Summers and K. John Scott. 1990. U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program, an Ecological Status and Trends Program. In: Federal Coastal Wetland Mapping Programs. Biological Report 90(18). Sari J. Kiraly, Ford A. Cross and John D. Buffington, Editors. U.S. Fish and Wildlife Service, Washington, DC. Pp. 71-78. (ERL,GB X754).

The U.S. Environmental Protection Agency (EPA) is initiating an Environmental Monitoring and Assessment Program (EMAP) to monitor the status and trends of the Nation's near-coastal waters, forests, freshwater wetlands, surface waters, agroecosystems, deserts, and rangelands. This program is also intended to evaluate the effectiveness of EPA policies in protecting the ecological resources of these systems. The monitoring data collected for all ecosystems will be integrated for national status and trends assessments. The near-coastal component of EMAP consists of four ecosystem categories: estuaries, wetlands, coastal waters, and the Great Lakes. The near-coastal ecosystems have been regionalized and classified, an integrated sampling strategy has been designed, and quality-control procedures and data-base management designs will be implemented. A demonstration project will be conducted in the Virginian biogeographical province in 1990, followed by a full-scale national implementation. EMAP will characterize national ecological resources to establish a baseline for monitoring and assessment. The characterization strategy involves the application of remote-sensing technology to obtain high-resolution data on selected sample sites and lower resolution data over broad geographic areas.

Gaston, Gary R., Steven S. Brown, Chet F. Rakocinski, Richard W. Heard and J. Kevin Summers. 1995. Trophic Structure of Macrobenthic Communities in Northern Gulf of Mexico Estuaries. Gulf Res. Rep. 9(2):111-116. (ERL,GB X805).

Trophic structure of estuarine benthic communities in the northern Gulf of Mexico was characterized according to the functional roles and geographic distributions of the macrobenthos. Macrobenthic organisms collected during two years of study were assigned to trophic groups to assess the relative utilization of detritus and other resources. Three groups of detritivores (less than 3%) and othersurface-deposit feeders, subsurface-deposit feeders, and filter feeders) were numerically dominant among the benthos, each of which accounted for 25-30% of total abundance across regions. Carnivorous macrobenthos also comprised an appreciable portion (12%), while omnivores (less than 3%) and other groups (less than 4%) were poorly represented. Dominance by detritivores is consistent with current concepts regarding the role of macrobenthos in processing detritus of Gulf of Mexico estuaries.

Paul, John F., K. John Scott, A. Fred Holland, Steven B. Weisberg, J. Kevin Summers and Andrew Robertson. 1992. Estuarine Component of the US E.P.A.'s Environmental Monitoring and Assessment Program. Chem. Ecol. 7(1-4):93-116. (ERL,GB X931).

The U.S. Environmental Protection Agency's Office of Research and Development has initiated the Environmental Monitoring and Assessment Program (EMAP) to monitor status and trends in the condition of the nation's near coastal waters, forests, wetlands, agro-ecosystems, surface waters, deserts and rangelands. The programme is also intended to evaluate the effectiveness of Agency policies at protecting ecological resources occurring in these systems. Monitoring data collected for all ecosystems will be integrated for regional and national status and trends assessments. The near coastal component of EMAP consists of estuaries, coastal waters, and the Great Lakes. Near coastal ecosystems have been regionalized and classified, and an integrated sampling strategy has been developed. EPA and NOAA have agreed to coordinate and, to the extent possible, integrate the near coastal component of EMAP with the NOAA National Status and Trends Program. A demonstration project was conducted in estuaries of the mid-Atlantic region (Chesapeake Bay to Cape Cod) in the summer of 1990. In 1991, monitoring continued in mid-Atlantic estuaries and was initiated in estuaries of a portion of the Gulf of Mexico. Preliminary results indicate: there are no insurmountable logistical problems with sampling on a regional scale; several of the selected indicators are practical and sensitive on the regional scale; and an efficient effort in future years will provide valuable information on condition of estuarine resources at regional scales.

Hyland, Jeffrey L., W. Leonard Balthis, Virginia D. Engle, Edward R. Long, John F. Paul, J. Kevin Summers and Robert F. Van Dolah. 2003. Incidence of Stress in Benthic Communities Along the U.S. Atlantic and Gulf of Mexico Coasts Within Different Ranges of Sediment Contamination from Chemical Mixtures. EPA/600/J-03/393. Environ. Monit. Assess. 81(1-3):149-161. (ERL,GB X1036).

Synoptic data on concentrations of sediment-associated chemical contaminants and benthic macroinfaunal community structure were collected from 1,389 stations in estuaries along the U.S. Atlantic and Gulf of Mexico coasts as part of the nationwide Environmental Monitoring and Assessment Program (EMAP). These data were used to develop an empirical framework for evaluating risks of benthic community-level effects within different ranges of sediment contamination from mixtures of multiple chemicals present at varying concentrations. Sediment contamination was expressed as the mean ratio of individual chemical concentrations relative to corresponding sediment quality guidelines (SQGs), including Effects Range-Median (ERM) and Probable Effects Level (PEL) values. Benthic condition was assessed using diagnostic, multi-metric indices developed for each of three EMAP provinces (Virginian, Carolinian, and Louisianian). Cumulative percentages of stations with a degraded benthic community were plotted against ascending values of the mean ERM and PEL quotients. Based on the observed relationships, mean SQG quotients were divided into four ranges corresponding to either a low, moderate, high, or very high incidence of degraded benthic condition. Results showed that condition of the ambient benthic community provides a reliable and sensitive indicator for evaluating the biological significance of sediment-associated stressors. Mean SQG quotients marking the beginning of the contaminant range associated with the highest incidence of benthic impacts (73-100% of samples, depending on the province and type of SQG) were well below those linked to high risks of sediment toxicity as determined by short-term toxicity tests with single species. Measures of the ambient benthic community reflect the sensitivities of multiple species and life stages to persistent exposures under actual field conditions. Similar results were obtained with preliminary data from the west coast (Puget Sound).