Selenium Toxicity To Invertebrates: Will Proposed Thresholds for Toxicity To Fish and Birds Also Protect Their Prey?

Efforts to manage the environmental risks of selenium
(Se) in freshwater ecosystems have focused primarily on
fish and birds, with invertebrates most often considered only
as dietary sources of Se to higher trophic levels. Relatively
little attention has been given to the risk of Se toxicity
to invertebrates. Based on a review of 156 aqueous, dietary,
or internal Se concentrations associated with toxic
effects in 29 macroinvertebrate species, we found that
water concentrations associated with acute lethality varied
>1000-fold among taxa, whereas toxic dietary concentrations
varied ∼100-fold and toxic internal concentrations
varied about 30-fold. Sublethal effects occurred at ∼10-fold lower concentrations than lethality. Sublethal effects
occurred at 1−30 μg Se/g dry weight in invertebrate
tissue, a range that encompasses proposed dietary thresholds
for toxicity to fish and water birds, suggesting that Se
may cause toxic effects in some invertebrate species at
concentrations considered to be “safe” for the organisms
consuming them.