M2 AM Aquatic Ecotoxicology (Part 1)
Monday, 14 November 2005: 8:00 AM - 11:40 AM in Ballroom 2

(WIR-1117-835329) Resistance of Atlantic tomcod from the Hudson River to PCBs and TCDD, but not PAHs.

Wirgin, Isaac, Chambers, R,

ABSTRACT- Atlantic tomcod from the Hudson River (HR) bioaccumulate high burdens of PCBs and PCDD/Fs in various life stages and are exposed to elevated levels of PAHs. We used controlled exposures to evaluate whether environmentally relevant congeners and concentrations of PCBs, TCDD, and B[a]P could induce toxic responses in the offspring (F1s) and grand-offspring (F2s) of wild fish, and whether genetically based tolerance to these compounds exists in populations with a history of exposure. We exposed and compared toxic responses in early life-stages of HR tomcod to tomcod from two less-contaminated sources; Shinnecock Bay, New York (SB), and the Miramichi River, New Brunswick (MR). Eggs were exposed to a range of water-borne doses of a mixture of PCBs (0.01 to 100-fold) and TCDD that bracketed levels (x) measured previously in livers of juvenile HR tomcod. Eggs were also exposed to graded doses of B[a]P. Morphometric, developmental, behavioral, and viability endpoints and CYP1A1 mRNA expression were measured in eggs and larvae. Significant dose effects were evident within the SB and MR groups for the PCBs mix and TCDD. SB and MR fish exhibited lower viability, less activity, slower development, higher levels of abnormalities, and greater CYP1A1 expression than HR fish at doses at and above 1 x. HR eggs and larvae were largely insensitive to PCBs and TCDD across the entire range of doses in the F1 and F2 generations. But, CYP1A1 expression was equally inducible in HR and SB embryos by B[a]P. This suggests that more than one molecular pathway activates CYP1A1 expression in tomcod. Further studies showed that tomcod collected over a 100-mile stretch of HR are resistant to PCBs. The high levels of PCBs and TCDD that bioaccumulate in resistant HR tomcod probably biomagnify in an array of piscivorous fish species that consume tomcod in the Hudson River Estuary.

Key words: resistance, PCBs, TCDD, PAHs