Comparison of the sensitivity to heavy metals and pentachlorophenol of the mayflies <i>Deleatidium</i> spp. and the cladoceran <i>Daphnia magna</i>

Abstract

A laboratory testing protocol has been established for the mayfly Deleatidium spp. This involves incubation of organisms for 96 h at 15°C with continuous aeration. Under these conditions EC50 concentrations for Deleatidium were similar to those for the cladoceran Daphnia magna (48 h test) for four heavy metal toxicants (Cd 2+ , Cr 6+ , Cu 2+ , and Zn 2+ ) and one organic compound (pentachlorophenol). The EC 50 concentration for Zn 2+ was, however, markedly higher for Deleatidium , indicating lower sensitivity. Deleatidium showed a strong increase in sensitivity with increasing exposure time, suggesting that the organism may be relatively insensitive to short‐term (&lt; 24 h) elevations in heavy‐metal concentrations. Comparison with published data for other riverine invertebrates and fish suggests that Deleatidium is among the more sensitive species.