Impact of introduced seastars Asterias amurensis on survivorship of juvenile commercial bivalves Fulvia tenuicostata

摘要: The introduction and establishment of the predatory seastar Asterias amurensis in southern Australia is considered a major threat to benthic marine communities commercial bivalves. impact A. on soft sediment assemblage SE Tasmania was quantified, with particular attention effects predation survivorship recently settled juve- niles bivalve Fulvia tenuicostata. In manipulative experiment, densities F. tenuicostata juveniles were reduced by ca. 15 fold (from 580 35 m -2 ) presence seastars at background relative treatment without seastars. feeding survey, exhibited preference for following settlement over period from December 1997 January 1998, which comprised 80 50% seastar's stomach items Feb- ruary 1998 April respectively. However, preferred variety other prey taxa when abundance low, particularly bivalves, gastropods echi- noid Echinocardium cordatum. This indicates that may potentially affect taxa. results provide further support hypothesis amuren- sis largely responsible recent decline subsequent rarity large bivalves its current distribution Tasmania. potential have wider ecosystem level than short-term direct reported here concern.