KOLOK*, A.S.; PEAKE, E.B.; ROARK , S.A.; GUTTMAN, S.I.; University of Nebraska, Omaha; University of Nebraska, Omaha; Miami Univ. Oxford, Ohio; Miami Univ. Oxford, Ohio: Cu tolerance in fathead minnows: Insight from a laboratory selection experiment.

The objective of this study was to determine if the copper (Cu) tolerance of adult fathead minnows is heritable. The relative Cu tolerance of 96 adult fish was sublethally determined by comparing the aerobic swim performance of each individual before and after an 8 d exposure to a sublethal concentration of Cu. The reduction in swim performance due to the Cu exposure varied widely among individuals. Genetic analysis of the individuals revealed significant correlations between reduction in swim performance and genotypic variation at the glucosephosphate isomerase-1, phosphoglucomutase-1 and lactate dehydrogenase-2 enzyme loci. Based upon reduction in swim performance, the most Cu-tolerant, the most Cu-susceptible, and a group of randomly selected fish were bred to form three distinct lineages. Some of the larvae produced by each lineage were subjected to larval survivability tests. The median lethal concentration (LC50) for larvae produced by the Cu-tolerant adults was not significantly different from the LC50 for larvae produced by the Cu-susceptible fish; however, both LC50s were significantly greater than that of the controls. The remaining larvae were raised to adults then exposed to sublethal Cu concentrations for 8 d. There were significant differences in reduction in swim speed, whole body Na and whole body Cu concentrations among the adult offspring from the three different lineages. Our findings on the relative Cu tolerance of adult minnows, but not the larvae, are consistent with the hypothesis of genetic inheritance.