THE EFFECTS OF DRILLING MUDS ON MARINE INVERTEBRATE LARVAE AND ADULTS

A series of laboratory experiments tested the effects of drilling muds from an active platform off southern California an larvae and adults of marine invertebrates. Red abalone (Haliotis rufescens) were used to determine effects of drilling muds on fertilization, early developmen t, survivorship, and settlement, and experiments on adult brown cup co rals (Paracyathus stearnsii) tested effects on adult survivorship, via bility, and tissue loss. Exposures to drilling muds did not have an ef fect on abalone fertilization or early development. However, several e xposures to drilling muds resulted in weak, but significant, positive effects of drilling muds on settlement of competent larvae. In contras t, settlement of red abalone larvae on natural coralline algal crusts decreased with increasing concentrations of drilling muds. This sugges ts that drilling muds affect either the abalone's ability to detect na tural settlement inducers, or they affect the inducer itself. Exposure of brown cup corals to concentrations of drilling muds adversely impa cted their survivorship and viability. These effects were likely cause d by increased tissue mortality of the coral polyps.