Reproduction in mytilus edulis aoteanus and aulacomya maoriana (mollusca: bivalvia) from taylors mistake, new zealand

Abstract

At Taylors Mistake, New Zealand (43° 35’ S, 172° 47’ E), maturation of gametes of Mytilus edulis aoteanus and Aulacomya maoriana occurred as seawater temperature decreased in autumn and winter. Most individuals were morphologically ripe when temperatures were lowest, and spawning began as temperatures increased in spring. The spawning and redevelopment period was more prolonged for M. e. aoteanus (about 7 months) than for A. maoriana (2–4 months). A. maoriana was resting or of indeterminate sex in January and February (summer), but gametogenic activity was apparent in M. e. aoteanus throughout the year, with few individuals resting in the summer.The general pattern of gametogenic activity for M. e. aoteanus was comparable with that of Mytilus edulis planulatus reported from Western Australia, although a majority of the latter species were resting or of indeterminate sex during the summer, when seawater temperatures were warmer than in New Zealand. The apparent coincidence of spawning periods of the mussel species M. e. aoteanus, A.maoriana, Perna canaliculus and Xenostrobus pulex, which overlap spatially on New Zealand shores, raises the possibility of interspecific competition among larvae for settlement space. © 1977 Taylor & Francis Group, LLC.