New Zealand Journal of Marine and Freshwater Research abstracts

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Feeding ecology of whelks on an intertidal sand flat in north-eastern New Zealand

M. J. Stewart

Leigh Marine Laboratory
The University of Auckland
P.O. Box 349
Warkworth, New Zealand

R. G. Creese

Port Stephens Research Centre
Private Bag 1
Nelson Bay
NSW 2301, Australia

Abstract  The dispersion patterns and feeding behaviour of intertidal whelks were investigated in north-eastern New Zealand. Aggregations of whelks feeding on clams occurred regularly, with an average of 15–20 individuals per aggregation. Death of clams was attributable to predation in up to 50% of the aggregations, although scavenging of dead and moribund animals was the main activity of whelks. Laboratory and field studies showed that Lepsiella scobina (generally not considered a soft shore species) was the main whelk predator at Lews Bay, Whangateau Harbour, drilling a small neat hole through the clam shell. The distinction between Cominella spp. as predators or scavengers is not so clear. Reseeding of intertidal clams, Austrovenus stutchburyi, has been proposed as a technique for re-establishing populations in some degraded New Zealand estuaries. The impact of whelk predation has many implications for A. stutchburyi reseeding. Both L. scobina and Cominella adspersa may potentially prey on newly reseeded clams as they preferentially attacked small clams in the laboratory. On-growing to a larger size before reseeding may be advantageous although large size was not found to protect prey from predation. Additionally, no seasonal trend in whelk activity was found.

Keywords  predation; scavenging; drilling; clams; Cominella spp.; Lepsiella scobina

M03016; Online publication date 24 November 2004 Received 29 April 2003; accepted 27 August 2004
New Zealand Journal of Marine and Freshwater Research, 2004, Vol. 38: 819–831
0028–8330/04/3805–0819 © The Royal Society of New Zealand 2004

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