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Native spider crab causes high incidence of sub-lethal injury to the introduced seastar Asterias amurensis


Ling, SD and Johnson, CR, Native spider crab causes high incidence of sub-lethal injury to the introduced seastar Asterias amurensis, Proceedings of the 13th International Echinoderm Conference, 5-9 January 2009, Hobart, Tasmania, Australia, pp. 195-201. (2013) [Refereed Conference Paper]

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The northern Pacific seastar, Asterias amurensis (Lütken), is an invasive species established throughout the Derwent Estuary, southeast Tasmania. Here we report on field observations of predation on the seastar within its new environment. The spider crab Leptomithrax gaimardii (family Majidae), which characteristically aggregates in shallow water in winter, used its chelae to tear the body wall of A. amurensis and completely consume the seastar. Typically, the predatory interaction resulted in sub-lethal injury (arm damage) to the seastar. Sampling in the area of an aggregation of spider crabs revealed that ~70% (ranging from 50-87%) of the A. amurensis population incurred sub-lethal arm damage consistent with spider crab attack. Spider crabs were observed at other sites in the estuary, but were transient and rates of arm injury at these sites were much lower, ranging from 7-33%. The most common form of injury sustained by A. amurensis in the presence of spider crabs was damage to arm tips (62% of all injuries), followed by full arm loss (34%) and half-arm loss (5%). Near the peak of the ~2 month spider crab aggregation, very few injured seastars displayed evidence of arm regeneration, however rates of arm regeneration increased rapidly as the localised spider crab aggregation dispersed. Smaller A. amurensis were disproportionately represented among the injured seastars, while observations in situ and in aquaria revealed that injury may frequently occur during competition for mussel prey. These observations suggest that native predators within the seastars new range may be capable of inflicting localised seasonal impacts on this important introduced pest.

Item Details

Item Type:Refereed Conference Paper
Keywords:native spider crab, introduced seastar Asterias amurensis, predation
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Marine and estuarine ecology (incl. marine ichthyology)
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Effects of climate change on Australia (excl. social impacts)
UTAS Author:Ling, SD (Dr Scott Ling)
UTAS Author:Johnson, CR (Professor Craig Johnson)
ID Code:80073
Year Published:2013
Deposited By:IMAS Research and Education Centre
Deposited On:2012-10-21
Last Modified:2018-03-16
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