National Benthic Surveillance Project: Northeast Coast
Fish Histopathology and Relationships Between Lesions and Chemical Contaminants (1987-89)
Lyndal L. Johnson, Carla M. Stehr, O. Paul Olson, Mark S. Myers, Susan M. Pierce, Bruce B. McCain, and Usha VaranasiNational Marine Fisheries Service
Northwest Fisheries Science Center
Environmental Conservation Division
2725 Montlake Blvd. E.
Seattle WA 98112
U.S. DEPARTMENT OF COMMERCE
Barbara Hackman Franklin, Secretary
National Oceanic and Atmospheric Administration
National Marine Fisheries Service
Sin Lam Chan
Mary Jean Willis
This report presents and interprets the results of pathology studies conducted on winter flounder (Pleuronectes americanus) between 1987 and 1989 in conjunction with NOAA's National Status and Trends (NS&T) Program. In these studies, a variety of potentially contaminant-associated disease conditions were monitored in winter flounder collected from 22 Northeast Coast sites, and the relationship between disease occurrence and levels of organic chemical contaminants in sediment, stomach contents, and tissues was examined. Sampling was conducted primarily in spring of 1988 and 1989 (Cycles 5 and 6) as part of the National Benthic Surveillance Project (NBSP) of the NS&T Program, but to provide a more comprehensive view of pathological conditions in winter flounder from the Northeast Coast, data on winter flounder collected in Long Island Sound during 1987 and in Boston Harbor and adjacent embayments during the winter of 1988 were also included in this memorandum. In the three studies combined, a total of more than 1,500 fish were examined.
Embayments sampled included Salem Harbor, Boston Harbor, Massachusetts Bay, New Bedford Harbor, and Buzzards Bay in Massachusetts; Narragansett Bay in Rhode Island; Niantic Bay in Connecticut; several sites within Long Island Sound including New Haven, Norwalk, Bridgeport, and Rocky Point in Connecticut and Lloyd Point in New York; and Raritan Bay and Great Bay in New Jersey. The levels and types of chemical contaminants present in sediments from sampling sites within these embayments differed substantially. Among the most heavily contaminated sites were Mystic River and Quincy Bay in Boston Harbor, and Gravesend, West Reach, and East Reach sites in Raritan Bay. Sediments from these sites had elevated levels of all or most of the contaminants measured in this study, including aromatic hydrocarbons (AHs), polychlorinated biphenyls (PCBs), DDTs (DDT and its derivatives), and chlordanes. The New Bedford Harbor sampling site had very high concentrations of PCBs in sediments, but relatively low concentrations of other classes of contaminants. Lowest concentrations of nearly all classes of contaminants in sediment were found at the Plymouth Entrance site in Massachusetts Bay and at the Rocky Point site in Long Island Sound. The Rocky Point site served as a reference site for analyses of intersite differences in lesion prevalences. Detailed information on concentrations of contaminants in sediments from these sampling sites will be reported in a forthcoming Technical Memorandum.
Winter flounder were examined for necrotic, sclerotic, and proliferative lesions in the kidney, fin erosion, and a number of pathological conditions in the liver, including:
Prevalences of the lesion types described above were determined in winter flounder from each of the Northeast Coast sampling sites. In addition, logistic regression was used to examine the effects of selected biological and contaminant-associated risk factors (e.g., age, gender, site and season of capture, and levels of chemical contaminants in sediments and fish) on lesion occurrence. Logistic regression is a multivariate statistical method which is similar to stepwise multiple regression, but is uniquely suited to binomial or proportional data such as lesion presence or absence or lesion prevalence. This technique is frequently applied in epidemiological and epizootiological studies and has a distinct advantage over simple intersite comparison of lesion prevalences because it allows biological factors such as age and gender to be taken into account when evaluating relationships between disease and site of capture or other parameters associated with contaminant exposure.
Relationships between lesion prevalences and the following major classes of chemical compounds were examined: high molecular weight AHs containing 4-6 benzene rings (HAHs), low molecular weight AHs containing 1-3 benzene rings (LAHs), total AHs (LAHs + HAHs), PCBs, DDTs, and chlordanes. These classes of chemical compounds were chosen as potential risk factors because 1) they are found at high concentrations in sediments from a number of Northeast Coast sites; 2) they are generally present in estuaries located near metropolitan areas throughout the United States and thus represent an index of urban pollution; and 3) they are generally recognized as toxicants in fish or mammals. Moreover, concentrations of these contaminants in sediments were highly correlated with levels of the same compounds or their derivatives in stomach contents, liver, and bile of winter flounder, indicating that these compounds were being taken up and accumulated or metabolized by the fish. Concentrations of organic contaminants in all compartments were correlated with disease prevalences to evaluate the consistency of observed relationships; however, contaminant levels in liver and bile were considered to have the greatest relevance as toxicologic risk factors because they correspond most closely to actual uptake of toxicants by animals.
Although biomonitoring studies such as those reported here could benefit greatly by inclusion of a broader suite of contaminants and biological endpoints, the data gathered thus far provide significant indications that certain environmental contaminants are potential risk factors for pathological conditions observed in winter flounder, a benthic fish used as an indicator species for the assessment of environmental quality on the Northeast Coast. This correlational evidence, while being circumstantial, provides valuable insights into the potential involvement of certain groups of contaminants in disease initiation and progression, and will serve as a basis for the formulation of definitive cause-and-effect studies with potential etiologic agents present in urban environments.
The National Benthic Surveillance Project (NBSP) was initiated in 1984 as a component of the National Oceanic and Atmospheric Administration's (NOAA's) National Status and Trends (NS&T) Program, which was designed to assess the status of, as well as long-term changes in, the environmental quality of the Nation's coastal and estuarine waters. The NBSP is a cooperative effort between the National Marine Fisheries Service and the Coastal Monitoring and Bioeffects Division of the Office of Ocean Resources Conservation and Assessment of NOAA's National Ocean Service. The project's specific objectives are to measure concentrations of chemical contaminants in sediment and in bottom-dwelling fish species at selected sites in urban and nonurban embayments, to determine the prevalences of pathological conditions and other bioindicators of contaminant exposure in these same fish species, and to evaluate temporal trends in the above-mentioned parameters. One hundred sites in embayments along the Atlantic, Gulf and Pacific coasts, including Alaska, have been sampled since 1984, with each annual sampling referred to as a "cycle" (e.g., 1984 = Cycle 1). Prior to Cycle 5, the Northeast Fisheries Center was responsible for Northeast Coast NBSP sampling, and results of these studies are presented in Zdanowicz et al. (1986) and NOAA (1987, 1988).
This Technical Memorandum presents and interprets the results of histopathological studies conducted on winter flounder (Pleuronectes americanus formerly Pseudopleuronectes americanus) sampled from Northeast Coast sites between 1987 and 1989 as part of the NS&T Program. Pathological conditions described include a variety of idiopathic liver, kidney, and fin lesions. Some of these lesions, such as liver neoplasms and related lesions, are well established as histopathologic biomarkers of contaminant stress, while others have shown some promise as indicators but require additional testing. Prevalences of these lesions in winter flounder sampled from sites with different degrees of chemical contamination are compared. In addition, lesion prevalences are correlated with chemical exposure data to better understand the relationship between environmental contaminants and fish disease. This memorandum is not meant to comprehensively review the marine pollution literature; however, pertinent references are included in discussions of the most significant findings.
In addition to this publication, a separate Technical Memorandum is in preparation to provide detailed information on contaminant levels in winter flounder tissues and in sediments at the Northeast Coast sampling sites (Brown et al. in prep.). While data on sediment and tissue contaminant concentrations will be utilized in this pathology memorandum, the chemistry report should be consulted for more comprehensive information on tissue and sediment chemistry for Northeast Coast NBSP studies conducted during 1988 and 1989.
The National Benthic Surveillance Project (NBSP), a component of the National Oceanic and Atmospheric Administration's (NOAA's) Status and Trends (NS&T) Program, is designed to assess the status of the Nation's coastal and estuarine waters and monitor long-term changes in marine environmental quality. A key component of the NBSP is the utilization of histopathologic alterations in fish tissues as indicators of the effects of exposure to environmental contaminants on marine organisms. These histopathologic biomarkers are pathological conditions that either morphologically resemble lesions induced by the experimental exposure of mammals or fish to toxicants, or show evidence of a contaminant-associated etiology in field studies because they occur either exclusively or at significantly increased prevalences in fish from contaminated sites.
Probably the most commonly used histopathologic biomarkers are neoplastic and preneoplastic liver lesions, although recent studies indicate that certain associated degenerative and regenerative conditions may be equally or even more useful as biomarkers of anthropogenic stress (Myers et al. in press, Varanasi et al. in press). Liver cancer and related lesions have been reported in several species of bottomfish (e.g., English sole (Pleuronectes vetulus, formerly Parophrys vetulus) (McCain et al. 1977; Malins et al. 1984, 1985; Myers et al. 1987), white croaker (Genyonemus lineatus) (Malins et al. 1987; Myers et al. 1991, 1992); Atlantic tomcod (Microgadus tomcod) (Smith et al. 1979; Cormier 1986)) from chemically contaminated coastal areas. Associations between concentrations of chemical contaminants in sediments and fish tissues and certain of these lesions have been observed in field surveys (Malins et al. 1984, 1985; McCain et. al. 1988; Vogelbein et al. 1990), and have been further substantiated by statistical analyses and epizootiological models (Rhodes et al. 1987, Myers et al, 1990, 1991, 1992; Landahl et al. 1990). Moreover, in some species, including English sole, cause-and-effect relationships between selected contaminants and hepatic lesions similar to those observed in field-sampled animals have been demonstrated in long-term laboratory studies (Varanasi et al. 1987, Schiewe et al. 1991). Other pathological conditions, including fin erosion and renal lesions, have also shown some promise as bioindicators of contaminant exposure in fish (Dethlefsen 1980, Cross 1985, Wellings et al. 1976, Sherwood and Mearns 1977, Cross et al. 1985, Sindermann 1990, Reimschuessel et al. 1990, Hawkins et al. 1989, McCain et al. 1992), but require additional testing in both the field and the laboratory to confirm their chemical etiology.
Previous field studies suggest that liver lesions and other disease conditions in winter flounder (Pleuronectes americanus formerly Pseudopleuronectes americanus) may be reliable bioindicators of environmental degradation on the Northeast Coast. The occurrence of neoplastic and non-neoplastic liver disease in fish from contaminated areas, especially from sites within Boston Harbor, is well-documented, both in earlier NBSP sampling conducted by the Northeast Fisheries Center (Zdanowicz et al. 1986, NOAA 1987, 1988) and in studies by other investigators (Murchelano and Wolke 1985, 1991; Moore 1991, Gronlund et al. 1991). Elevated prevalences of fin erosion have also been reported in flounder from contaminated sites along the Northeast Coast (Williams 1981, Ziskowski and Murchelano 1975). At present, however, there is relatively little information available on how levels of specific contaminants in sediments and winter flounder tissues are related to disease occurrence, or on the effects of biological factors such as age and gender on disease prevalence in this species.
This report presents the results of pathological studies conducted on winter flounder collected from Northeast Coast sites between 1987 and 1989 as part of the NS&T Program. The major objectives of the study were 1) to determine the prevalences of fin erosion and selected hepatic and renal lesions in winter flounder from the Northeast Coast sampling sites; 2) to examine the effects of biological variables such as age, gender, and sampling season on lesion occurrence; and 3) to assess the relationship between levels of chemical contaminants in sediments and fish and lesion prevalences.
Sampling was primarily conducted during Cycles 5 and 6 (1988 and 1989) of the Northeast Coast NBSP, but to provide a more comprehensive view of pathological conditions in winter flounder from the Northeast Coast, data from winter flounder collected in Long Island Sound in 1987 (Gronlund et al. 1991) and in Boston Harbor and adjacent embayments during the winters of 1988 and 1989 (Johnson et al. 1992, in press) are also included in this report. Histopathological examination of tissues and chemical analyses were carried out in our laboratory in a uniform fashion for all three studies, so all data included here are comparable.
Lesion types monitored in winter flounder included fin erosion; necrotic, sclerotic, and proliferative lesions in the kidney; and a number of suspected toxicopathic liver lesions such as neoplasms, putatively preneoplastic foci of cellular alteration, and nonneoplastic proliferative and degenerative conditions. A variety of other pathological conditions, such as parasitic infections, were noted in flounder examined in this study, but they will not be described in detail in this report as there is little evidence that they have a chemical etiology (Hinton et al. 1992).
The following classes of chemical contaminants were included in the analysis as potential risk factors : high molecular weight aromatic hydrocarbons (AHs) containing 4-5 benzene rings (HAHs), low molecular weight AHs containing 2-3 benzene rings (LAHs), total AHs (LAHs + HAHs), polychlorinated biphenyls (PCBs), DDT and its derivatives, DDD and DDE (DDTs), and chlordanes. These classes of chemical compounds were chosen because 1) they were present at high concentrations in sediments from a number of Northeast Coast urban sites; 2) they are among the most prevalent contaminants in estuaries adjacent to metropolitan areas throughout the United States, and thus represent an index of urban pollution (Varanasi et al. 1988, 1989a); and 3) they are generally recognized as toxicants in fish or mammals (Klaassen et al. 1986).
Concentrations of these organic contaminants or their metabolites were measured in several compartments (i.e., sediments, stomach contents, liver, and bile) to give a comprehensive picture of exposure and relationships between contaminant levels in all three compartments and idiopathic disease. However, contaminant levels in liver and bile were considered to have the greatest relevance as toxicologic risk factors, because they are most representative of the actual uptake of toxic compounds by fish. It should be noted that other types of contaminants, such as dioxins or organometals, may also play a role in the development of disease in winter flounder and other fish species. However, because methodologies for measuring concentrations of these compounds in fish and sediments that are cost-effective and appropriate for a large-scale monitoring program are not currently available, it was not possible to include them in the NBSP at this time.
Trace metal analyses of sediments, liver tissue, and stomach contents were conducted by the Southeast Fisheries Science Center, and data on metal concentrations will not be presented here. Analyses of metals from previous NBSP samplings on both the West Coast (Varanasi et al. 1988, 1989a) and the Northeast Coast (NOAA 1988) indicated that there was little relationship between tissue concentrations of metals and concentrations of metals in sediment in any of the fish species examined. These findings suggest that metals may not be bioavailable to fish, or that their uptake and accumulation are governed by complex processes that make tissue concentrations of metals a poor indicator of environmental exposure. Consequently, no attempt was made to correlate metal concentrations with fish disease.
Logistic regression (Breslow and Day 1980, Schlesselman 1982) was used to assess the influence of biological and contaminant-associated risk factors on lesion occurrence. The logistic function is considered a basic model for dose-response relationships and logistic regression analysis is frequently applied in epidemiological and epizootiological studies. This technique is similar to commonly-used stepwise multiple regression procedures, but is uniquely suited to binomial or proportional data (e.g., lesion prevalence or lesion presence or absence). Results of these analyses and their relationship to other studies of pollution-associated disease in winter flounder will be discussed below.