Assessing the ecological impacts of an introduced seastar: the importance of multiple methods

摘要: Introduced species are having major impacts in terrestrial, freshwater, and marine ecosystems worldwide. Given that resources for management limited only a small percentage of invaders likely to cause large ecological change, priorities should be based on the severity immediate anticipated native assemblages commercial species. This paper synthesizes work current predicted an introduced predatory seastar (Asterias amurensis) soft sediment assemblages, including subject fishing, Derwent Estuary other areas southeast Tasmania. Due absence baseline data prior arrival presence anthropogenic stressors estuary, estimating impact is difficult. To help overcome weaknesses any single method, our assessment rests 'weight evidence' from multiple approaches. Results experimental manipulations at scales, detailed observations feeding, field surveys over range spatial scales with without provide strong evidence predation by responsible decline subsequent rarity bivalve live just below or surface Estuary. The suggest densities Tasmanian coast attain levels Estuary, there direct effects particularly populations dwelling bivalves, several seastar's ability exploit broad food than functional importance bivalves systems, we predict broader indirect assemblages. We would unable reach these same conclusions approach assessing impacts. overall picture combination methods different provides more information sum results separate lines investigation.