PARENT SESSION
Poster Session # 7: Restoration, Resource Management, and Conservation.

Monday, August 4 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Effects of acid mine contaminated sediments on Ctenodaphnia magna in laboratory bioassays.

D'sa, Jean^*,1, Johnson, Kelly^*,2, ¹ Environmental Studies, Ohio University, Athens, Ohio, U.S.A² Department of Biological Sciences, Ohio University, Athens, Ohio, U.S.A.

ABSTRACT- Acid mine drainage or AMD is a major worldwide environmental problem that adversely affects both surface and ground waters. AMD streams are not only characterized by low pH but also by high concentrations of heavy metals. Although the effects of metals in the water column on macroinvertebrates have been reasonably well investigated, the effects of metal contaminants in the sediments are less well understood. Understanding the conditions under which sediments may or may not retain toxicity to biological communities is important for predicting the success of specific remediation efforts. Laboratory bioassays using Ctenodaphnia magna (Order: Cladocera) were performed to test the AMD contaminated sediments for toxicity and sediment transplantation field experiments were carried out to determine the residual toxicity of these sediments over time. Sites (around Athens, Ohio) with reduced pH levels, visible metal precipitates and elevated water column concentrations of iron, aluminum, and manganese were identified, and 7-day laboratory bioassays in static containers using C. magna were carried out. Sediments from all four of the AMD impacted sites were found to be highly toxic to the daphnia. Toxicity was correlated to reduced pH levels but was not correlated with any specific metal content. In another experiment, AMD contaminated sediments were filled in baskets and transplanted into the bed of a healthy stream for a week. Washed sediments of each site were collected on the 2nd, 5th and 7th day and were monitored for toxicity by performing 5-day laboratory bioassays using C. magna. After 7 days in the clean stream, the same aluminum and iron-contaminated substrates were no longer found to be toxic to the daphnia. These results suggest, that sediments at these sites will not retain toxicity after remediation of the AMD input.

Key words: laboratory bioassays, acid mine drainage, sediment toxicity, Ctenodaphnia magna