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Variability in the impact of an introduced predator (Asterias amurensis: Asteroidea) on soft-sediment assemblages


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Ross, DJ and Johnson, CR and Hewitt, CL (2003) Variability in the impact of an introduced predator (Asterias amurensis: Asteroidea) on soft-sediment assemblages. Journal of Experimental Marine Biology and Ecology, 288 (2). pp. 257-278. ISSN 0022-0981

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The introduction and establishment of the predatory asteroid Asterias amurensis in coastal waters
of southern Australia is considered a major threat to benthic marine assemblages and commercial
bivalve species. We compare the impact of the seastar in experiments on three soft-sediment
assemblages. The experiments were carried out immediately beyond the current range of the seastar
in southeast Tasmania. This allows us to assess the repeatability, and hence predictability, of the type
and magnitude of the impact of A. amurensis on soft-sediment assemblages. Responses to
manipulations at the species level were dissimilar across the three experiments, reflecting marked
initial differences in the three assemblages at both the species and functional group levels. However,
at the functional group level, there were notable similarities in the impact of the seastar on the
different assemblages. When potential prey taxa were separated into functional groups reflecting
ecological availability (e.g. surface dwelling vs. deep burrowing bivalves), seastar effects were
largely restricted to the surface bivalves. While the effect of seastar predation on surface bivalves
was common in all three assemblages, the magnitude of the impact varied both among and within
assemblages. Variability in the impact of A. amurensis at both levels appeared to be largely due to
differences in relative availability of prey species. Overall, the results of these experiments indicate
that while the impact of the seastar is broadly predictable at the functional group level, the exact nature of seastar effects is likely to be site- and time-specific given the inherent natural variability in
soft-sediment assemblages and the seastar's responses to them.

Item Type: Article
Keywords: Asterias amurensis; Introduced species; Predation; Soft sediments; Variability
Journal or Publication Title: Journal of Experimental Marine Biology and Ecology
Page Range: pp. 257-278
ISSN: 0022-0981
Identification Number - DOI: 10.1016/S0022-0981(03)00022-4
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Definitive version is available online at

Date Deposited: 21 Jun 2007
Last Modified: 18 Nov 2014 03:18
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