The northern Pacific seastar, Asterias amurensis, is arguably southern Australia’s most damaging marine pest species, and has exerted massive ecological impacts since its discovery in Port Phillip Bay in the mid-1990s. While the enormous fecundity and reproductive potential of A. amurensis is well recognised, relatively little attention has been paid thus far to the phenomenon of autotomy (arm shedding), which could well be a response to various environmental stressors, and an important reproductive pathway for the species.
This ongoing investigation aims to quantify the extent of autotomy occurring amongst captive seastars that are held in aquaria at the Aquaculture Training and Applied Research Centre at Melbourne Polytechnic, where seastars will be observed daily (with the aid of time-lapse footage) for the entire duration of the project to determine if seastars autotomize, and to what extent.
The study will also focus on seastar removals at Point Cooke and Jawbone Marine Sanctuaries, where the number of seastars that have lost at least one arm are considerable, being 66.7% (n = 72) and 22.7% (n = 803), respectively, and which could be indicative of predation for an animal that apparently does not have many natural predators in southern Australian waters.