Evidence of estrogenic endocrine disruption in smallmouth and largemouth bass inhabiting Northeast U.S. national wildlife refuge waters: A reconnaissance study.

Intersex as the manifestation of testicular oocytes (TO) in male gonochoristic fishes has been used as an indicator of estrogenic exposure. Here we evaluated largemouth bass (Micropterus salmoides) or smallmouth bass (Micropterus dolomieu) form 19 National Wildlife Refuges (NWRs) in the Northeast U.S. inhabiting waters on or near NWR lands for evidence of estrogenic endocrine disruption. Waterbodies sampled included rivers, lakes, impoundments, ponds, and reservoirs. Here we focus on evidence of endocrine disruption in male bass evidenced by gonad histopathology including intersex or abnormal plasma vitellogenin (Vtg) concentrations. During the fall seasons of 2008-2010, we collected male smallmouth bass (n=118) from 12 sites and largemouth bass (n=173) from 27 sites. Intersex in male smallmouth bass was observed at all sites and ranged from 60% to 100%; in male largemouth bass the range was 0-100%. Estrogenicity, as measured using a bioluminescent yeast reporter, was detected above the probable no effects concentration (0.73ng/L) in ambient water samples from 79% of the NWR sites. Additionally, the presence of androgen receptor and glucocorticoid receptor ligands were noted as measured via novel nuclear receptor translocation assays. Mean plasma Vtg was elevated (>0.2mg/ml) in male smallmouth bass at four sites and in male largemouth bass at one site. This is the first reconnaissance survey of this scope conducted on US National Wildlife Refuges. The baseline data collected here provide a necessary benchmark for future monitoring and justify more comprehensive NWR-specific studies.

Lead contamination in American woodcock (Scolopax minor) from Wisconsin.

An initial survey of lead levels in American woodcock (Scolopax minor) from Wisconsin was conducted in 1998 using wing bones from hunter-donated woodcock. The results of this initial survey indicated that young-of-year woodcock were accumulating extremely high levels of lead in their bones. Similar collections were made (using steel shot) between 1999 and 2001. The combined results of this collection indicated that 43.4% of young-of-year woodcock (range 1.5-220.0 microg/g dry wt) and 70% of woodcock chicks (range 9.6-93.0 microg/g dry wt) had bone lead levels in the elevated range (>20 microg/g dry wt). Blood samples were collected from chicks at a site considered elevated based on bone lead results (Mead Wildlife Area) and a site considered background (Navarino Wildlife Area). These samples were analyzed for lead concentration and aminolevulinic acid dehydratase activity. The mean blood lead concentrations of woodcock chicks from both sites did not reach levels that are considered elevated in waterfowl (>0.200 microg/ml). However, blood lead concentrations of chicks from the Mead Wildlife Area were significantly higher than lead levels in chicks from Navarino Wildlife Area (p = 0.002). Although the ultimate sources of lead exposure for Wisconsin woodcock currently remain unidentified, anthropogenic sources cannot be ruled out. Our results indicate that elevated lead exposure in Wisconsin woodcock is common and begins shortly after hatch.

2,2',4,4',5,5'- and 3,3',4,4',5,5'-hexachlorobiphenyl alteration of uterine progesterone and estrogen receptors coincides with embryotoxicity in mink (Mustela vision).

Female mink (Mustela vison) are highly sensitive to organochlorine (OC)-induced reproductive impairment. However, mechanisms of this reproductive toxicity are unknown. We have investigated the possible role of steroid receptors in embryotoxicity and reduced neonate weights. Anestrous, juvenile female mink and pregnant adult mink were exposed to 3,3',4,4',5,5'-hexachlorobiphenyl (3HCB), a coplanar polychlorinated biphenyl (PCB), or 2,2',4,4',5,5'-hexachlorobiphenyl (2HCB), a noncoplanar PCB congener. Both congeners impaired 17 beta-estradiol-stimulated (24 hr after ip administration of 100 micrograms E2 beta ip) up-regulation of uterine nuclear estrogen receptors (ERn) in anestrous mink. Embryotoxicity and reduced embryo growth were first observed 14 days after exposure to 0.4 mg 3HCB/kg > 0.8 mg 3HCB/kg > 20 mg 2HCB/kg. In pregnant mink, all 3HCB treatments significantly increased progesterone receptor dissociation constants (PR Kd). ER concentration and PR total receptor number (Rt) were increased by 20 mg 2HCB/kg > 0.8 mg 3HCB/kg, but were unaffected by 0.4 mg 3HCB/kg. Serum E2 beta was below assay detection limits. Progesterone (P) concentrations were increased by 2HCB, decreased by 0.8 mg 3HCB/kg, and unchanged by 0.4 mg 3HCB/kg. Hepatic cytochrome P450 (P450) was induced 1.8-fold in anestrous and 2.2-fold in pregnant mink by 3HCB. Ethoxyresorufin-O-deethylase (EROD) was induced 13- and 4-fold in anestrous and pregnant mink, respectively. 2HCB exposure resulted in decreased P450 concentration in anestrous juveniles, but had no effect on P450 during gestation or EROD activity at any time. We propose that embryotoxicity and retarded embryo growth result from impairment of PR function and that differences in the efficacy of HCB treatments are a result of their dose-dependent, partial estrogenic actions which increase PR Rt via up-regulation of ER.