Acclimation of life‐history traits to experimental changes in environmental contaminant concentrations in brown bullhead (Ameiurus nebulosus)

Abstract

One adaptive mechanism aquatic populations use to facilitate tolerance to environmental contaminants is acclimation. Polychlorinated biphenyls (PCBs) are a globally ubiquitous class of persistent organic contaminants that have been linked to reproductive impairments in fish. The authors used female brown bullhead (Ameiurus nebulosus) to test whether acclimation of reproductive life-history traits occurs in response to changes in sum PCB exposure. They compared egg diameter, gonadosomatic index (GSI), and fecundity of fish directly caught from wild populations exposed to a range of contaminant concentrations (acute), to those collected from the same populations a year before, which were placed in a clean environment to clear their contaminants throughout that year (cleared). Sum PCB concentrations were also determined for each individual. Brown bullhead from acute treatments had significantly greater sum PCB concentrations compared with cleared treatments. Egg diameter and GSI metrics were greater in cleared treatments compared with acute treatments (by 6 and 14%, respectively). Treatment effect (i.e., acute or cleared), as opposed to where the fish were collected from, accounts for 72 to 89% of the variation in the reproductive life-history trait variables. No difference in fecundity was found between acute and cleared treatments. The authors found support that acclimation of reproductive life-history traits occurs to changes in sum PCB concentration. To their knowledge, the present study is the first experimental test of acclimation responses of female life-history traits to contaminants in wild populations.