Fish whole-body selenium: interspecies translation experiment

Area of Science:

• Environmental Science
• Ecotoxicology
• Aquatic Ecology

Background:

• Selenium contamination in Newport Bay necessitates developing Total Maximum Daily Load (TMDL) standards.
• Different fish species inhabit distinct areas of the watershed, complicating contamination assessments.
• Mosquitofish and sunfish species exhibit different distributions within the watershed.

Purpose of the Study:

• To compare selenium bioaccumulation across different fish species and watershed areas using mesocosms.
• To inform the development of selenium TMDLs for Newport Bay freshwater drainages.
• To evaluate the efficacy of fish mesocosms for comparing bioaccumulation in allopatric species.

Main Methods:

• Utilized fish mesocosms to hold mosquitofish in areas where they are not native.
• Collected tissue samples from caged mosquitofish and resident bluegill sunfish to measure bioaccumulated selenium.
• Compared selenium tissue concentrations and ratios between species under different conditions and assumptions.

Main Results:

• Initial comparisons of selenium bioaccumulation ratios between mosquitofish and bluegill sunfish required adjustments.
• Altering assumptions regarding the time to reach selenium equilibrium in mosquitofish tissues improved ratio agreement.
• Extrapolation of mesocosm results and careful consideration of trophic levels were critical for accurate comparisons.

Conclusions:

• Fish mesocosms are a valuable tool for comparing selenium bioaccumulation between allopatric species.
• Accurate assessment of bioaccumulation requires careful consideration of species-specific equilibrium times and trophic positions.
• This methodology aids in establishing reliable selenium contamination benchmarks for regulatory purposes.