Oil-induced disruption of foraging behaviour of the asteroid keystone predator, Coscinasterias muricata (Echinodermata)

A prey-localization test allowed the observation of the foraging behaviour of Coscinasterias muricata in the presence of Mytilus edulis and the disrup tion of this behaviour following oil exposure. Asteroids were exposed to di lutions of water-accommodated fractions (WAF) of Bass Strait stabilised cru de oil (control, 2%, 10%). Effects of exposure (4 d) and depuration (20 d) were quantified using circular statistical analyses. Observations suggested that disruption of behaviour might be concentration-dependent. Control ast eroids successfully located mussels during tests. A small proportion (3 of 16) of asteroids exposed to 2% WAF also located the mussels, while asteroid s exposed to 10% WAF did not. Following depuration, exposed asteroids recov ered their chemoreception capacities. It is concluded that (1) Coscinasteri as muricata is able to locate prey mussels through chemoreception, (2) expo sure to oil disrupts its foraging behaviour, and (3) the effect is reversib le.