Factors affecting settlement and early post-settlement survival of the NewZealand abalone Haliotis australis

This paper describes studies on the settlement of the abalone Haliotis aust ralis Gmelin. Ten-day-old H. australis larvae had a slower rate of settleme nt than 5-day-old larvae. A high proportion of veliger larvae had the abili ty to prolong the searching phase of settlement and delay metamorphosis, ev en over prepared settlement surfaces but radula development continued at a similar rate in both settled and swimming larvae. In any one batch of larva e settlement was slow and asynchronous and post-settlement survival was low . Light was shown to influence the swimming behaviour of larvae in settleme nt tanks, with more larvae swimming in the dark than in the light. The impl ications of these behaviours are discussed in relation to larval and postla rval energetics and feeding.