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

Ross, DJ, Johnson, CR and Hewitt, CL 2002 , 'Impact of introduced seastars Asterias amurensis on survivorship of juvenile commercial bivalves Fulvia tenuicostata' , Marine Ecology Progress Series, vol. 241 , pp. 99-112 .

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

Item Type: Article
Authors/Creators:Ross, DJ and Johnson, CR and Hewitt, CL
Keywords: Seastar; Introduced species; Predation; Impacts; Bivalves; Soft sediment; Asterias amurensis
Journal or Publication Title: Marine Ecology Progress Series
ISSN: 0171-8630
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