TP11 Metals in the Environment: Aquatic Biological Perspectives
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(GAL-1116-878875) Responses of Daphnia magna Strauss to episodic exposures of selenium.

Gallagher, J¹, Hoang, C¹, Tomasso, J ², Klaine, S¹, ¹ Department of Biological Sciences, Clemson University, Pendleton, South Carolina, U.S.A.² Department of Wildlife Fisheries Biology, Clemson University, Clemson, South Carolina, U.S.A.

ABSTRACT- The acute toxicity of selenium to aquatic biota has been extensively studied since the 1970s. Most of the toxicity experiments consisted of an invertebrate being exposed to selenium in a constant aqueous exposure. Since constant exposure of toxicants to invertebrates in the environment is unusual, episodic or pulse exposures may more accurately represent true risk to aquatic biota. This research characterized the responses of Daphnia magna Strauss when exposed to sodium selenate in 21–d episodic toxicity experiments, with varying exposure times (6 to 96–h) and exposure concentrations (100 to 3000 g/L). These static–renewal experiments consisted of four replicates per exposure concentration for each exposure time, plus a control, and five D. magna neonates per replicate. At concentrations > 200 g/L, survival of D. magna was a function of both exposure time and selenium concentration. Adverse toxicological effects were not observed until greater than 6 hours after exposure. Implications of these latent toxic effects will be discussed.

Key words: Daphnia magna, selenium, episodic, toxicity