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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Ecotoxicology
LABORATORY ASSESSMENT OF AN IMPACTED LOTIC SYSTEM USING AN ECOLOGICALLY RELEVANT TEST ORGANISM.
A.J. Kennedy, D.S. Cherry, and R.J. Currie. Department of Biology, Virginia Tech, Blacksburg, VA, USA, 24061
Studies investigating the ecotoxicological impacts of industrial effluents on freshwater biota typically utilize US EPA recommended test organisms such as Ceriodaphnia dubia, Daphnia magna and Pimephales promelas. Although these organisms are susceptible to a variety of toxicants, they are not universally the most sensitive. Additionally, the ecological relevance of utilizing planktonic lentic organisms (e.g., C. dubia and D. magna) to protect lotic benthos is subject to criticism. Thus, a resident species approach should be adopted using a sensitive benthic collector-filterer following development of a practical experimental design. A 99.8% reduction in mean mayfly abundance was observed for surveys conducted in the Leading Creek Watershed (southeast Ohio) below a coal processing effluent with a mean specific conductivity (SC) of 8091 (7750-8750) μS/cm. Subsequently, the mayfly, Isonychia bicolor, was exposed for 7-days in specialized lotic microcosms to a simulation of this effluent (9000 μS/cm) using a dilution series. Based on LOAECs, I. bicolor survival was a more sensitive endpoint to SC (1562 μS/cm) than were 7-day C. dubia survival (6040 μS/cm) and fecundity (3710 μS/cm). Thus, traditional test organisms may not adequately protect benthic macroinvertebrate assemblages in systems impaired by high SC discharges.
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