PARENT SESSION

PH08 Metals in the Environment: Aquatic Biological Perspectives
Exhibit Hall
8:00 AM - Thursday

(PH096) Use of whole-body sodium to characterize recovery from copper stress in larval Pimephales promelas.

Zahner, H¹, VanGenderen, E¹, Tomasso, J¹, Klaine, S¹, ¹ Clemson Institute of Environmental Toxicology, Clemson University, Pendleton, SC, USA

ABSTRACT- Many contaminants enter receiving streams sporatically and result in fluctuating exposures. This is true for point source discharges from wastewater treatment plants and other industrial effluents. Actual aquatic exposures vary in magnitude, duration, and frequency. In particular, the ability of an organism to survive multiple exposures may be a factor of the recovery time between exposures. This research used a physiological endpoint, whole body sodium, to characterize recovery of larval Pimephales promelas (fathead minnow) from acute copper exposures. The mechanism of copper toxicity to fish is through disruption of ionoregulation resulting in a loss of sodium and eventually mortality. Continuous copper exposure resulted in rapid sodium loss (30%) within the initial 12 hours. Static-renewal toxicity tests were used to characterize recovery of the whole-body sodium from pulse exposures (3, 6, 9 hours) to copper. The test was renewed at exposure termination with control water, which constituted the recovery environment (<5 g Cu²⁺/L). Organisms demonstrated an ability to recover whole-body sodium (to within 90% of control) after exposure to concentrations below the LC50 (20, 25, 30, 35 g Cu²⁺/L). The time to recovery was dependent upon the duration and the magnitude of the copper exposure. These results may facilitate development of a physiologically-based model to predict organisms response to copper in receiving streams.

Key words: Episodic Exposure, Whole-body Sodium, Copper, Fathead Minnow