Funding Program: Contaminant Biology
Statement of Problem: The goal of this proposed project is to determine the effects of dietary selenium on desert pupfish (Cyprinodon macularius) that inhabit Imperial Valley agricultural drains and shoreline pools at the Salton Sea. Results of this project will be used to determine if proposed management actions, specifically actions taken as part of the Imperial Irrigation District's Habitat Conservation Plan, are sufficient to conserve the pupfish in the Imperial Valley. To directly assess the potential toxic effects of dietary selenium on fish in the Imperial Valley, survival, growth, egg production and hatching, biochemical indicators, teratogenesis, and bioaccumulation of selenium by pupfish will be evaluated in chronic exposures covering multiple stages of the pupfish life cycle. Threshold concentrations for toxic effects selenium will be established based on selenium concentrations in the diet and in the tissue of pupfish. Fractionation and speciation of selenium among tissue compartments will be conducted for diet samples and pupfish tissue samples to provide more suitable measures of residue-based Se effects thresholds in these chronic dietary exposures, selenium exposures occurring in wild pupfish populations, and in other fish (e.g., Gambusia) and invertebrates that make up the diet of fish inhabiting the Imperial Valley. Fractionation and speciation of Se in tissues has recently been identified as a critical data gap in the interpretation of virtually all previously conducted selenium ecotoxicological studies.
Objectives: 1. Develop methods for culturing pupfish 2. Develop methods for conducting early-life stage toxicity tests with pupfish 3. Conduct acute water-borne exposures with pupfish 4. Develop methods for dosing selenium in the diet of pupfish 5. Evaluate effects of dietary selenium exposure on selenium bioaccumulation and reproduction of desert pupfish 6. Evaluate effects of dietary and maternal selenium exposure on early life-stage pupfish 7. Determine base selenium concentrations in diet and tissues of desert pupfish 8. Develop methods for the fractionation and speciation of selenium among tissue compartments for pupfish diet and pupfish tissue.