1990 Demonstration Report
Demonstration Report 1990
Weisberg, S.B., J.B. Frithsen, A.F. Holland, J.F. Paul, K.J. Scott, J.K Summers, H.T. Wilson, R. Valente, D.G. Heimbuch, J. Gerritsen, S.C. Schimmel, R.W. Latimer.
1993. EPA/620/R-93/006. U.S. Environmental Protection Agency, Environmental Research Laboratory, Office of Research and Development, Narragansett, RI
The Environmental Monitoring and Assessment Program (EMAP) is a comprehensive environmental monitoring network designed to 1) estimate the current status and trends in the condition of the nation's ecological resources on a regional basis, with known confidence; 2) seek associations between human-induced stress and ecological condition; and 3) provide periodic statistical summaries and interpretive reports on ecological status and trends to resource managers and the public. The program was initiated to provide the information necessary for formulating future environmental policies by answering the following questions: What is the current extent of our ecological resources, and how are they distributed geographically? What proportions of the resources are currently in good or acceptable condition? What proportions are degrading or improving, in what regions, and at what rates? Are these changes correlated with patterns in environmental stresses? Are adversely-affected resources improving overall in response to control and mitigation programs?
Three characteristics of EMAP differentiate it from most previous environmental monitoring programs. First, sampling in EMAP is probabilitybased so that estimates of status and trends can be made with quantifiable confidence. Second, EMAP monitoring and assessments focus on biological indicators of response to natural and human-induced stress; indicators of pollutant exposure and habitat condition are sampled simultaneously to provide a context for interpreting biological indicators. Third, the scale of EMAP monitoring is regional and national, rather than local.
The program is organized into Resource Groups responsible for conducting assessments of seven categories of environmental resources: forests, wetlands, surface waters, near coastal waters, arid lands, agricultural ecosystems, and the Great Lakes. Administered by the EPA's Office of Research and Development, EMAP is an integrated federal program that is planned and implemented in cooperation with the National Oceanic and Atmospheric Administration, the U.S. Fish and Wildlife Service, the U.S. Forest Service, the U.S. Bureau of Land Management, the U. S. Agricultural Research Service, and the U.S. Geological Survey.
The first stage in implementing EMAP involves conducting demonstration projects for each Resource Group. Demonstration projects provide the opportunity to illustrate the kinds of assessments that can be conducted using EMAP data and to work with users of the data to select the most appropriate indicators for evaluating problems of concern in that resource category. Demonstration projects also provide information for refining the sampling design and identifying and resolving logistical difficulties associated with regional monitoring in each resource category on a limited scale, before EMAP monitoring is implemented nationwide.
This report describes the first EMAP demonstration project, which was conducted in estuaries of the mid-Atlantic states (the Virginian Province) in 1990 by the Near Coastal Resource Group. Estuaries were selected for the first demonstration project because of their biological productivity and the current intense public interest in restoring and maintaining estuarine resources. The objectives of the project were to demonstrate the utility of regional scale monitoring using a probability-based sampling design for assessing the condition of estuarine resources, establish standardized methods for estuarine monitoring, identify and resolve logistical problems associated with large-scale sampling, test and develop biological indicators of estuarine environmental quality, and collect the data on regional-scale variability in ecological parameters needed to evaluate and refine the sampling design. Each of these objectives is addressed in individual sections of this report. A summary of those sections follows.
The 1990 Demonstration Project involved 500 sampling visits to 217 sites from Cape Cod to the mouth of the Chesapeake Bay. A series of indicators that are representative of the overall health of estuarine resources was measured at each site. These indicators were selected to address three major attributes of concern: 1) biotic integrity, or the existence of healthy, diverse, and sustainable biological communities; 2) pollutant exposure, or the condition of the chemical environment in which biota live; and 3) aesthetics, representing societal values related to public use of estuarine resources. Habitat indicators, such as depth, salinity, temperature, and the physical characteristics of the sediment, were also measured.
Methods (Section 2) and Logistics (Section 3)
One characteristic of the EMAP-Estuaries program is that the entire province is sampled within a limited time period (approximately six weeks) using standardized methods to ensure comparability of data within and among sampling years. One of the goals of the 1990 Demonstration Project was to develop and document these standardized methods and associated quality assurance protocols. This objective was accomplished successfully. Field and laboratory manuals for all EMAP-Estuaries sampling activities are available. EMAP is promoting these methods and associated QA protocols to EPA Regions, states, and local agencies responsible for monitoring to facilitate comparability of information from multiple monitoring programs within the province.
The 1990 Demonstration Project also served as a means for evaluating the logistical feasibility of conducting a regional monitoring program in estuaries and identifying the most difficult obstacles involved therein. The 1990 Demonstration Project was a logistical success. More than 90% of the scheduled samples were collected, and they were all obtained without injury to crew members or significant loss of equipment. More than 95% of the data collected passed QA requirements, and specific alterations to the crew training program were identified to resolve the few data collection problems in future years. Several innovative technologies incorporated into the 1990 Demonstration Project for evaluation were deemed a success, such as the use of on-board computers in small boats to record station position at the time of sampling, and the use of bar-coding to track sample shipments to the numerous laboratories responsible for processing.
Indicator Development and Testing (Section 4)
A major accomplishment of the 1990 Demonstration Project was developing and applying a methodology for calibrating and validating biological indicators of estuarine condition. The methodology uses discriminant analysis to identify the most effective combination of measurements for distinguishing assemblages at regional reference sites from those at sites with known environmental perturbations. Such biological indicators, which are applicable over a range of latitudes and habitats, had not been identified previously. Developing these indicators is important for EMAP and should prove helpful in other Agency efforts for developing biocriteria.
Benthic invertebrate assemblages were the most successful biological indicators. Bottom-dwelling organisms are particularly useful as indicators because they integrate exposure conditions over long periods of time (months to years), and because their relative immobility prevents them from avoiding pollution exposure. Based on studies conducted during the 1990 Demonstration Project, five attributes of the assemblage related to the number of species, number of amphipods, number of capitelid polychaetes, number of bivalves, and the average weight per polychaete can correctly differentiate clean reference sites from polluted sites with about 90% certainty. Initial steps have been taken to validate this index; however, additional data from future years of the program will be used to further refine the index and continue the validation process.
Fish assemblage indicators also are promising for distinguishing between polluted and unpolluted sites, but additional data will be required to reduce uncertainty. The mobility of fish presents the biggest obstacle to using them for identifying conditions at a particular site. Even if a fish indicator that successfully discriminates sites of high and low quality cannot be validated until later years of the program, there are still several fish parameters, such as prevalence of visible pathological disorders, that convey meaningful information on a regional or watershed basis.
Measures of pollution exposure also were evaluated during the 1990 Demonstration Project. For instance, variability in dissolved oxygen concentrations in the province was examined by deploying continuouslyrecording meters for periods of up to 60 days at a subset of sites. Although DO was found to be quite variable at individual sites, it was stable enough on a regional basis for making provincewide estimates of condition. Improved methods for measuring dissolved oxygen on a regional scale are being developed and tested in 1991 based on the findings of the 1990 Demonstration Project.
Design Evaluation (Section 5)
One of the primary objectives of the 1990 Demonstration Project was to determine the precision with which status can be estimated using the present design. At the province level, confidence intervals surrounding status estimates for each indicator measured during the 1990 Demonstration Project were less than 10% of the areal extent of the province. The uncertainty associated with these estimates is anticipated to decrease substantially after completing a four-year sampling cycle. Estimates developed at the subprovince level, such as for individual estuarine systems like the Chesapeake Bay, were less precise because fewer samples were collected in the subpopulations, but estimates were still within 15% of the actual areal extent. Confidence intervals for these subpopulations will also contract when the four-year sampling cycle is completed.
Another objective of the Demonstration Project was to estimate sources of variability for a selected indicator (the benthic index) and incorporate this information into a power analysis model to assess its power for trend detection using the present sampling design and sample density. Estimates of variability were generated from two sources: the EMAP sampling program and an ongoing monitoring program in the lower Chesapeake Bay. The power for trend detection was found to be sensitive to the estimate for interannual variability. Using the estimate generated from EMAP data, the likelihood of detecting a 2% per year change in the area of degraded benthic invertebrate assemblages over 12 years was greater than 99%. Using the lower Chesapeake Bay data set to estimate variance, the power for detecting a 2% per year change was only about 60%. Neither data set was ideal for estimating interannual variability; the EMAP data set was limited temporally, and the Chesapeake Bay data set was limited spatially. As EMAP continues to collect data over the next several years, the power analysis will be refined to better define the power of the program for detecting trends over decades.
The stability of several indicators was evaluated across three sampling intervals (mid-June to late-July; late-July to the end of August; early to late September) to define the boundaries of the sampling window. The most appropriate sampling period was determined to be late July through August because 1) dissolved oxygen values are at annual low values; 2) contaminant exposure is greatest because of low dilution flows and peak metabolic activity associated with highest water temperatures; and 3) living resources are most abundant, maximizing the probability of collecting organisms required for assessments.
Sample allocation in the 1990 Demonstration Project was accomplished after stratifying estuaries into three classes (large estuaries, large tidal rivers, and small estuarine systems). Without this stratification, the large tidal river and small estuarine system classes, which are perceived to be at risk from different types of stresses, would not have been sampled sufficiently to make assessments with acceptable levels of uncertainty. Alternative stratification schemes based on more dynamic characteristics, such as salinity and sediment type, were examined and found to have logistical shortcomings that rendered them less appropriate than the present design.
Another design alternative examined was the use of index sites in large tidal rivers and in small estuarine systems. Whereas random sites are designed to estimate areal extent, index sites are located in the areas of a system most likely to exhibit a problem if one exists (deep, depositional sites) and are used to estimate the percent of systems experiencing environmental degradation. Index sites added little value to the program. The biggest impediment to using index sites was that existing sediment maps of the Virginian Province are inadequate to define depositional areas accurately.
Preliminary Evaluation of Estuarine Status (Section 6)
When fully implemented, EMAP will provide regional and national assessments of ecological status and trends for the nation's environmental resources based on a four-year sampling cycle. The multi-year baseline is intended to minimize the effect of natural interannual variability due to climate and other factors. The preliminary evaluation of the condition of estuaries in the mid-Atlantic region provided in this report represents a first attempt at presenting statistically unbiased, regional-scale information to a broad audience and is intended to elicit discussion about assessment needs. The evaluation is preliminary because some indicators have not been validated fully, a process that will require several years of regional-scale data. The estimates presented are based on a single year of data rather than the four-year running average that is the basic unit of EMAP assessment; nonetheless, province-level evaluations of ecological condition that are unavailable from other sources are possible with the data:
The biotic integrity of estuaries in the Virginian Province was evaluated by measuring the condition of benthic invertebrate (bottom-dwelling animals) assemblages. Between 16%-30% of the estuarine area in the Province had benthic resources that were degraded compared to regional reference sites.
Biotic integrity was also assessed by examining the prevalence of visible pathological disorders (lesions, tumors, etc.) of fish. Four of every thousand fish in the province had a visible pathological disorder. The prevalence in demersal fish (those living in close contact with the bottom sediments) was several times that in pelagic fish (those living primarily in the water column). Less than 0.1% of fish that are commercially or recreationally harvested had visible pathological disorders.
Ten-day solid-phase toxicity tests using indigenous biota were conducted to examine the condition of estuarine sediments. Eight percent of the sediments in the province were estimated to be acutely toxic.
Sediments were screened for contaminants using the same list of analytes used in the NOAA National Status and Trends Program. Based on this list of analytes, 39% ±7% of the province was estimated to have concentrations of contaminants in the sediments that potentially cause at least sublethal biological effects. Metals, lead and zinc in particular, were the most prevalent contaminants at these concentrations.
High concentrations of Clostridium perfringens, a bacterial tracer of sewage pollution, were found in an estimated 9% +_ 4% of the province.
Small estuarine systems, including harbors, bays and coastal embayments, had the highest proportion of toxic sediments, sediments containing contaminant concentrations of biological concern, and sediments containing high levels of Clostridium. They also had the highest proportion of fish with pathological disorders. These small systems typically are overlooked in monitoring programs that concentrate effort along the main axis of large estuarine systems.
Between 14%-28% of the area in the province had dissolved oxygen concentrations below 5 ppm, the water quality standard for many states in the province. Nine percent of the area was estimated to have concentrations below 2 ppm, which is considered stressful to most biota.
Of the largest systems in the Virginian Province, Long Island Sound had the highest proportion of area with oxygen concentrations less than 5 ppm; Chesapeake Bay had the highest proportion of area with concentrations below 2 ppm.
Anthropogenic marine debris (trash) was estimated to be present in 9-19% of the estuarine area of the province. Paper and plastic accounted for most of this debris.
Conclusions (Section 7)
The 1990 Demonstration Project in the estuaries of the Virginian Province was a success by any measure. Each of the six objectives established for the project was met. The preliminary assessment of the environmental condition of the Virginian Province identified differences in the extent of environmental degradation between specific habitats and classes of estuaries that should be of great interest to resource managers. A suite of biological response, pollutant exposure, and habitat indicators were evaluated and will form the core of future EMAP-Estuaries monitoring activities. The collection and sample processing methods used during the 1990 Demonstration Project received rigorous testing and are appropriate with minor modification. They are available for use by other estuarine monitoring programs. Results from the 1990 Demonstration Project were used to evaluate the EMAP sampling design and suggested that no major design modifications are necessary. Assessment techniques, including the development of indices describing the benthic assemblage, fish, and aesthetics, were applied to real data and appear to be a good way to characterize conditions for resource managers. Several more years of data are required to determine the condition of estuaries in the Virginian Province with the desired level of confidence and to validate biological indicators with the required degree of sensitivity. EMAP has identified most of the technological problems that must be overcome for its implementation in estuaries and is well on the way to resolving those difficulties.