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Ovarian development was monitored in female English sole Parophrys vetulus Girard from three sites in Puget Sound: Sinclair Inlet and Port Susan, where fish are normally resident, and University Point, a known spawning area for English sole. Histological changes in ovary and liver as well as changes in plasma estradiol and vitellogenin levels, gonadosomatic index, hepatosomatic index, and calcium, phosphate, magnesium, glucose, triglyceridesm total protein, and albumin concentrations in the plasma over the reproductive cycle were assessed. Vitellogenesis in female English sole began in the early fall, and swapping activity reached its peak in February. Oocyte development was group synchronous with two distinct clutches of oocytes in the maturing ovary. In general, the cytological and physiological changes which English sole underwent during the reproductive cycle were similar to those observed in other teleost species. However, certain distinctive features were observed, including a high prevalence of atresia of nonyolked oocytes.

Vitellogenic female English sole were sampled from four areas in Puget Sound that varied in the nature and degree of chemical contamination. The fish were then injected with an analogue of Luteinizing Hormone Releasing Hormone (LHRH) in the laboratory to induce spawning. Ability to spawn, time to spawn, larval viability, and initial concentrations of plasma estradiol and vitellogenin [measured as alkaline-labile protein associated phosphate (ALP)] were assessed. In general, low initial plasma estradiol and ALP concentrations and subsequent reproductive impairment were most common in English sole from sites where levels of sediment contaminants [e.g. polycyclic aromatic hydrocarbons and polychlorinated biphenyls (PCB)] and measures of contaminant exposure in fish (hepatic PCB concentrations and aryl hydrocarbon hydroxylase activity) were highest, and where pollution-associated liver lesions in fish (i.e. neoplasms, foci of cellular alterations, specific degeneration/necrosis, and storage disorders) were most prevalent. Additionally, the time to spawn was found to be inversely correlated with initial plasma estradiol concentrations. Spawning success was found to be positively correlated with initial plasma estradiol and ALP concentrations as determined by logistic regression analysis; nearly 62% of the variability in the spawning response could be accounted for by these factors. Fertilization success was also found to be positively correlated with initial ALP concentrations, whereas fish captured from contaminated sites produced lower proportions of normal larvae. Overall, these findings suggest that contaminant exposure may result in poor reproductive success of female English sole. This may be related to a hormone imbalance or to slower ovarian development (non-synchronous timing) of female English sole from contaminated sites.

A consistent and statistically significant association between prevalence of hepatic neoplasms in free-living sole (Parophrys vetulus) and levels of anthropogenic polycyclic aromatic hydrocarbons in bottom sediment from sites of fish capture was documented in a series of studies conducted over a period of 7 years in Puget Sound, Washington. This result strengthens the evidence supporting a causal relationship between exposure to sediment-associated hydrocarbons and development of hepatic neoplasms in this bottom-dwelling marine fish species. Prevalences of two other distinct categories of idiopathic hepatic lesions-megalocytic hepatosis and steatosis/hemosiderosis-also showed consistent, statistically significant associations with polycylic aromatic hydrocarbon concentrations in bottom sediment, and association with prevalence of a third category (putatively preneoplastic foci of cellular alteration) approached statistical significance. On the basis of other studies, megalocytic hepatosis and foci of cellular alteration are both considered to be important precursor lesions in the stepwise histogenesis of hepatic neoplasms.

Investigation of the interactive effects of representatives of three classes of compounds was performed, using English sole (Parophrys vetulus) as the test organism, juvenile fish were exposed orally to cadmium chloride and Aroclor 1254 (PCB), either independently or simultaneously, for a 4-wk period, followed by exposure to seawater-accommodated No. 2 diesel fuel for 2 wk. Blood was collected for analysis of serum constituents, and tissue samples were examined for histological changes. Hepatocellular necrosis, regeneration, and karyomegaly were observed. Differential lesion prevalences were observed among the exposure groups, with high proportions among cadmium-exposed fish, low proportions among PCB-exposed fish, and intermediate proportions in combination cadmium- plus PCB-exposed fish. Levels of aspartate aminotransferase activity and magnesium in the sera of these groups exhibited similar patterns. Depressed serum calcium levels in both PCB-exposed and cadmium- plus PCB-exposed groups were found after the first week, and lower serum albumin concentrations occurred in all cadmium- and PCB-exposed groups following the third week. Subsequent exposure to No. 2 diesel fuel produced few effects in any of the exposure groups. The observed antagonistic effect of Aroclor 1254 against cadmium toxicity emphasizes the importance of employing multiple as well as single contaminant exposure in toxicity studies.

English sole, Parophrys vetulus, from eight locations within Puget Sound, U.S.A. were examined for histological abnormalities of the liver and kidney. A total of 1083 fish were collected between February 1979 and June 1984 in nine separate sampling periods. Idiopathic lesions, i.e. lesions of unknown cause, were classified into eight hepatic and four renal lesion categories. The significance of certain potential risk factors associated with lesion prevalences, including age, gender, site of capture, season of capture and year of capture, were assessed by logistic regression. The odds ratios for the significant risk factors were also calculated. Site of capture and age of the examined fish were found to be the most important factors for most of the observed lesion types, e.g., hepatic neoplasms and foci of cellular alteration, whereas year and season of capture were significant influences for only a few lesion types, e.g., specific and nonspecific degenerative/necrotic lesions of the liver. Gender of examined fish was not found to be a significant factor for any of the lesion types. These results emphasize the importance of including certain potential influences, such as age and season of capture, in the analysis of field-collected organ pathology data.

Statistical comparisons were made between the relative mean concentrations of metabolites of aromatic compounds in bile (as estimated by a high-performance liquid chromatography/fluorescence detection method) and idiopathic liver lesions in English sole (Parophrys vetulus) from eleven Puget Sound sites. A significant positive correlation was found between prevalences of neoplasms, foci of cellular alteration, megalocytic hepatosis and total hepatic lesions and the concentrations of metabolites of aromatic compounds. These findings provide further evidence of the putative relationship between aromatic compounds and serious idiopathic liver diseases in bottom-dwelling fish.

A 4-year multidisciplinary study was conducted on relationships between pollutants and diseases of fish in Puget Sound, WA. In this study, high concentrations of a large number of anthropogenic chemicals such as petroleum hydrocarbons, polychlorinated biphenyls (PCBs) and other chlorinated compounds, pesticides, and metals were found in certain Puget Sound sediments. For example, over 900 individual organic compounds were detected in sediment from one urban bay (Commencement Bay), and evidence was obtained for the presence of numerous additional compounds. Many of the chemicals accumulated in bottom-dwelling fish, and high levels of certain toxic chemicals in the urban bays were linked to serious diseases (e.g., liver carcinomas) of English sole (Parophrys vetulus) and other demersal fish species. It was concluded that application of the approach used would reveal comparable serious pollution-related health problems in marine biota in other urban coastal areas of the world.

High prevalences of idiopathic hepatic lesions, including neoplasms (e.g., hepatocellular carcinomas, cholangiocellular carcinomas) (27%, 20 of 75 fish) and foci of cellular alteration (putative preneoplastic lesions) (44%, 33 of 75 fish), were found in English sole (Parophrys vetulus) exposed to creosote-contaminated sediments in Eagle Harbor, Puget Sound, WA. Sediments from the contaminated region of the harbor contained particularly high concentrations of aromatic hydrocarbons (e.g., benzo(a)pyrene and benz(a)anthracene), and a variety of nitrogen-containing aromatic compounds (e.g., carbazole and acridine). The composition of the aromatic compounds was characteristic of creosote. Dramatically lower concentrations of aromatic compounds were found in sediments from a reference site in which the bottom-dwelling fish examined were free of detectable neoplastic or preneoplastic hepatic lesions. Food organisms in the stomachs of the English sole from Eagle Harbor contained substantially higher concentrations of aromatic hydrocarbons than comparable organisms from the reference site. The concentrations of individual aromatic hydrocarbons in muscle and liver from the Eagle Harbor fish were low; however, high concentrations of metabolites of aromatic compounds were present in the bile. The findings strongly suggest an association between exposure to creosote and the prevalence of hepatic lesions, including neoplasms, in the bottom-dwelling fish, and furthermore support the putativemore » role of aromatic hydrocarbons in liver carcinogenesis in fish.« less

High prevalences of idiopathic liver lesions, including 7.5% hepatic neoplasms (e.g., hepatocellular and cholangiocellular carcinomas) and 16.7% foci of cellular alteration (putative preneoplastic hepatic lesions), were found in English sole (Parophrys vetulus) from waters near Mukilteo, a small community on Puget Sound in Washington State. Sediments from the sampling sites contained particularly high concentrations of aromatic hydrocarbons. Substantially lower concentrations of these compounds were found in sediments from another Puget Sound (reference) site in which fish showed no evidence of hepatic neoplasms or foci of cellular alteration. Stomach contents from the fish at Mukilteo contained substantially higher concentrations of the chemicals than did stomach contents of fish from the relatively uncontaminated site. High concentrations of metabolites of aromatic compounds were measured in the bile of fish from Mukilteo. These findings support previously observed relationships between sediment chemicals (e.g., aromatic hydrocarbons) and high prevalences of liver lesions in English sole from Puget Sound. In addition, a dietary route of uptake by English sole of environmental chemicals, including known carcinogens, was documented.

A comprehensive description of the histopathologic characteristics of a spectrum of idiopathic lesions in feral English sole (Parophrys vetulus), a bottom-dwelling flatfish, from Puget Sound, Washington State, is presented. Among these lesions are unique degenerative conditions, regeneration, storage disorders, foci of hepatocellular alteration (putative preneoplastic lesions), hepatocellular and biliary neoplasms, and nonneoplastic proliferative conditions, all of which morphologically resemble the lesions induced by various hepatocarcinogens-hepatotoxins in experimental exposures of fish and/or rodents. Results from a statistical analysis of the patterns of co-occurrence of these lesions in English sole are consistent with the concept, developed from experimental studies of liver carcinogenesis in rodents, that there are morphologically identifiable steps representing progression toward hepatic neoplasms. This is the first study in which it has been possible to demonstrate a close morphological congruity between a set of idiopathic hepatic lesions in any feral population and an established series of hepatic lesions inducible in rodents by certain hepatocarcinogens under laboratory conditions. Since sediments from the habitats occupied by the fish in this study have been shown to contain multiple hepatocarcinogens, the findings strengthen cumulative evidence that English sole are useful as indicators of exposure to hepatocarcinogens in aquatic environments. 156 references.

Relationships between selected serum components and microscopically detected idiopathic liver and kidney lesions were evaluated for English sole, Parophrys vetulus, sampled from urban and non-urban areas of Puget Sound, Washington. The normal range for each serum chemistry parameter was based on English sole with no lesions, or sole with minor parasitic conditions or with lesions in tissues other than liver and kidney which did not significantly affect serum chemistry values. Generally, sole with idiopathic liver lesions had significantly different haematocrit values and levels of serum albumin, calcium, and bilirubin when compared to sole which were free of idiopathic liver and/or kidney lesions. Serum aspartate aminotransferase and alanine aminotransferase activity and serum levels of glucose, total protein, phosphates and magnesium were also abnormal, but appeared to be associated only with certain types of liver lesions. No association between kidney lesions and abnormal serum chemistry values was identified. In addition, English sole sampled from some urban areas of Puget Sound had particular serum chemistry values and liver lesion prevalences which were significantly different from those of sole sampled from non-urban areas. These findings support the hypothesis that sole near highly urbanized environments may display other signs of impaired health in addition to high prevalences of tissue lesions. Thus, measurements of serum chemistry parameters, in conjunction with histopathological examination, appear to be useful techniques for evaluating the health of English sole.