SREL Reprint #1964

Genetic and demographic responses of mosquitofish (Gambusia holbrooki Girard 1859) populations stressed by mercury

Margaret Mulvey1, Michael C. Newman1, Ann Chazal1, M. Michele Keklak1, M. Gay Heagler1, and L. Stan Hales, Jr2

1University of Georgia, Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, South Carolina 29802
2Zoology Department, University of Georgia, Athens, Georgia 30602

Abstract: Genetic and demographic changes in mosquitofish populations are reported after chronic (111 d) exposure to mercury. Sex ratios, normally female-biased in field populations, were also female-biased in control mesocosms. However, the sex ratio was male-biased in the mercury treatments. Frequencies of glucosephosphate isomerase-2 (Gpi-2) allozymes for fish exposed to mercury differed from initial frequencies and from those of control fish. In a selection-component analysis, female sexual selection was statistically significant for the mercury-treated fish; the proportion of females that were gravid differed among Gpi-2 genotypes. The number of developing embryos per female also differed among Gpi-2 genotypes. Mercury had genotype-specific effects on mosquitofish reproduction in addition to genotype-specific effects on mortality reported earlier. These effects may reflect metabolic qualities of the Gpi-2 genotypes or loci closely linked to the Gpi-2 locus.

Keywords: Gambusia holbrooki; Fish; Mercury; Genetics; Demography

SREL Reprint #1964

Mulvey, M., M.C. Newman, A. Chazal, M.G. Heagler, and L.S. Hales Jr. 1995. Genetic and demographic responses of mosquitofish (Gambusia holbrooki Girard 1859) populations stressed by mercury. Environmental Toxicology and Chemistry 14:1411-1418.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).