Ant communities in a selenium-contaminated habitat

Habitat disturbances, such as pollution, have the potential to alter ecosystem functioning by impacting arthropod species diversity in the affected habitat. In order to explore the effects of an environmental contaminant on ant communities, we conducted a survey of ant species diversity in an area having previously experienced selenium contamination.  Kesterson Reservoir is located in the San Joaquin Valley, CA, which has naturally abundant levels of the metalloid selenium (Se). This 1200ac reservoir experienced contamination during the 1970s from the surrounding agricultural drainage waters, resulting in detrimental effects among the breeding waterfowl. Previous research exploring the effects of this contaminant, have focused mainly on birds, fish, and mammals, with comparatively little investigation into its impact on terrestrial invertebrates. Here, we report on the preliminary findings of our sampling effort. Soil concentrations were found to vary by location rather than habitat type, where the southernmost sites contained greater levels of Se. Ants were found to differ in body concentrations between species, which may be due to differences in feeding preferences and/or detoxification strategies. Several ant species were also found nesting in soil containing Se levels much greater than levels discovered toxic to ants in laboratory studies. We also report on the preliminary results for differences in ant species composition and abundance as it relates to soil and plant selenium concentrations at each collection site. The findings of this research lead to important questions regarding the possible effects of introduced contaminants to not only native arthropod species, but invasive species as well.