Linking Chemical Tolerance to reproductive fitness in fish from contaminated environments

Title: Linking chemical tolerance to reproductive fitness in fish from contaminated environments. The disruptive effects of polychlorinated biphenyls (PCBs) on reproduction in a number of vertebrates (67, 1,34) including fish (33, 42, 35), are well established and include altered hormone levels (26), reduced fecundity (10), decreased hatching success (26), and lower offspring survival (26,35). PCB resistant fish display lowered levels of the pollutant metabolizing enzyme cytochrome P450-1A (CYPIA) in response to PCB exposure relative to reference fish (22). My dissertation research to date has characterized a PCB contaminated system (13,16) and demonstrated differential CYPIA response in resident fish (15). I have demonstrated the presence of three phenotypes in resident fish; fish that display acquired resistance, natural resistance, and lack of resistance to PCB mediated CYPIA induction (15). I propose to build on these results by evaluating the possible mechanistic links among resistance, reproductive function, and population abundance. While many of the toxic effects of PCBs are known to be mediated via the aryl hydrocarbon receptor (AhR)/CYP1A pathway, the consequences of resistance on PCB mediated reproductive disruption are unknown. I hypothesize that resistance to PCBs confers resistance to the adverse reproductive effects of PCBs, potentially leading to community level shifts in favor of resistant organisms in highly contaminated areas.