T6 PM Immune and Endocrine Disruption: Detection and Implication
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 324-326

(NAC-1117-818532) Bacterial challenges to a wild PCB-adapted population of the estuarine fish Fundulus heteroclitus.

Nacci, D¹, Champlin, D¹, Gomez-Chiarri, M², Cohen, S.³, ¹ US EPA ORD NHEERL, Narragansett, RI, USA² University of Rhode Island, Kingston, RI, USA³ San Francisco State University, San Francisco, CA, USA

ABSTRACT- A population of estuarine fish, Fundulus heteroclitus (mummichogs), indigenous to an estuarine Superfund site, New Bedford Harbor (NBH), MA, demonstrate evolved tolerance to some of the toxic effects of local polychlorinated biphenyl (PCB) contamination: a unique model to study effects of long-term PCB exposures on sensitive biological processes such as reproduction, early development, growth and immune function. For example, NBH mummichogs and their progeny are profoundly tolerant of dioxin-like effects on early development. Some studies suggest that growth rates and reproductive output of NBH fish are comparable to uncontaminated populations, but other studies have shown that NBH fish are sensitive to some of the disrupting effects of PCBs, as indicated by vitellogenin production by males. To test whether long-term exposure to PCBs also affect immune responses of NBH mummichogs, we conducted laboratory assays to measure short-term survival following injection of cultured bacteria, Vibrio harveyi. We tested field-collected fish from NBH and relatively uncontaminated reference sites over the summer breeding season when the presumed cost of reproduction might increase disease susceptibility, and into the fall when increases in adult mortality have been observed in NBH on occasional years. Surprisingly, survival was higher in NBH fish, especially males. A similar pattern of survival was demonstrated in Vibrio challenges to laboratory-reared second generation fish from both sites, although population responses did not differ significantly. While the specific mechanisms by which toxicity and compensation are achieved are not yet understood, these studies contribute to our understanding of the potential for endocrine disrupting chemicals to affect the persistence of wild fish populations.

Key words: Fundulus, Bacterial challenge, PCBs