Chemical cues from predators and damaged conspecifics affect byssus production in the green-lipped mussel Perna viridis

Juveniles of the green-lipped mussel Perna viridis (Bivalvia: Mytilidae) were exposed to either chemical cues of damaged conspecifics or predator, including the swimming crab Thalamita danae and the muricid gastropod Thais clavigera . Byssus production was monitored for 48 h but the highest production rate occurred in the first 6 h. Longer and thicker byssal threads with a larger total volume were produced by P. viridis exposed to damaged conspecifics and predators as compared with the control. Numbers of individuals which shed stalks during the experiment varied significantly from 0 to 50%, and with a significantly higher value obtained for the control. Results indicated that byssus production is a plastic response which could be induced by exposure to chemical signals from predators and damaged conspecifics, the latter producing the largest response. Firmer byssal attachment not only reduces predation risk but also non-predation mortality by securing an animal more effectively to its habitat.