Effects of effluent contamination of wetlands on population level changes in Gambusia holbrooki

While presence/absence of endocrine disruption has been widely observed within polluted wetlands, relatively few data have addressed population level changes for any species. This paper investigated the effects of endocrine disruption on the phenotypic sex ratio, size structure, biomass, and density of Gambusia holbrooki populations in wetlands used for storage of 1) tertiary treated sewage effluent; 2) urban stormwater runoff; and 3) wetlands without effluent supplementation (control wetlands). Those wetlands that had previously been determined to have endocrine disruption effects on G. holbrooki had lower density and biomass of fish than other wetlands. In contrast, the pattern of variation in the average length and phenotypic sex ratio of fish was not consistent with the effects of endocrine disruption.