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Tissue residues of total mercury (Hg), total polychlorinated biphenyls (PCBs), and lipid-based PCBs; plasma concentrations of endocrine biomarkers; and reproductive and histologic biomarkers were assessed in 460 carp (Cyprinus carpio), bass (Micropterus salmoides and Micropterus dolomieui), and bullhead (Ameiurus nebulosus) collected from eight sites across the Hudson River Basin in the spring of 1998 to determine if endocrine disruption was evident in resident fish species and to evaluate contaminant-biomarker interrelations. Total PCBs in bed sediments (maximum 2,500 μg kg−1) could explain 64 to 90% of the variability in lipidbased PCB residues in tissues (maximum 1,250 μg PCB g-lipid−1) of the four species. The 17β-estradiol to 11-ketotestosterone ratio, typically less than 1.0 in male fish and greater than 1.0 in females, exceeded 1.4 in all male largemouth bass and 35% of male carp and bullhead at one site 21 km downstream from a major PCB source. Endocrine biomarkers were significantly correlated with total Hg in female smallmouth bass and carp, and with lipid-based PCBs in males of all four species. Empirical evidence of endocrine modulation in blood plasma of male and female fish from sites with and without high PCB residues in bed sediments and fish tissues suggest that PCBs, Hg, or other contaminants may disrupt normal endocrine function in fish of the Hudson River.

We report here on studies designed to asses the effects of paper mill effluents on non-reproductive functions of free-ranging and captive Florida largemouth bass (Micropterus salmoides floridanus). This was accomplished by conducting an outdoor tank study, in which fish were exposed to well water or to 10%, 20%, 40%, and 80% full strength effluent for 28 or 56 days, and by sampling largemouth bass from sites within the St. Johns River, Florida, upstream and downstream from a paper mill plant. Blood and plasma samples from fish from the tank study and from fish sampled from the ambient sites were analyzed for over 20 variables. We also determined liver and spleen weights and examined them histologically. The most significant finding from the tank study was an increase in the concentration of albumin and hepatosomatic index for bass exposed toor = 20% effluents for 56 days. Spleenosomatic index and number of melanomacrophage centers were decreased in bass from effluent-dominated sites (Palatka and Rice Creek), whereas concentrations of calcium, phosphorous, glucose, and creatinine were elevated in fish from these sites, compared to fish from reference streams. Fish from Rice Creek also had fewer red blood cells, and male bass from Palatka had lower concentrations of cholesterol. Plasma concentrations of albumin and hepatic concentrations of glutathione were elevated in males from Palatka, and both females and males from Rice Creek had higher concentrations of globulin. These results indicate a complex pattern of effects of paper mill effluents on several physiological functions. However, despite the myriad of treatment and site-related effects, most physiological parameters fell within normal ranges when compared to reports on largemouth bass and other freshwater species.

Four wetland restoration sites in the Emeralda Marsh Conservation Area located in central Florida, USA were flooded between 1992 and 1994. Florida Fish and Wildlife Conservation Commission stocked largemouth bass in the flooded areas from 1992 to 1996. In 1996, organochlorine pesticides (OCPs) were measured in flooded soils and in black crappie, brown bullhead catfish, and largemouth bass from the four sites. Areas 5 and 7 had the highest concentrations of total residual OCPs in the flooded soils, including dieldrin (385±241 μg/kg), sum of DDT, DDD, and DDE (7,173±1,710 μg/kg), and toxaphere (39,444±11,284 μg/kg). Sum of chlordane residuals was highest in area 5 (1,766±1,037 μg/kg). ANOVA indicated significant differences in location and fish muscle tissue concentrations for chlordane residuals, DDT residuals, and dieldrin. Fish from areas 5 and 7 had the greatest concentrations of chlordane residuals, DDT residuals, and dieldrin, which corresponded to the higher soil concentrations in these two areas. OCPs in muscle tissue were below the U.S. Food and Drug Administration action limits for human consumption. For three-year-old bass collected from Area 5, mean concentrations of chlordane residuals, DDT residuals, and dieldrin were 15–17 times higher in ovary tissue and 76–80 times higher in fat tissue compared with muscle tissue. Mean toxaphene levels in bass ovary and fat tissues were 9 and 39 times higher, respectively, than in muscle tissues. Tissue OCP concentrations were consistent with site OCPs, regardless of fish species.