Variation in Incidence and Severity of Injuries among Crown-of-Thorns Starfish (Acanthaster cf. solaris) on Australia's Great Barrier Reef

Despite the presence of numerous sharp poisonous spines, adult crown-of-thorns starfish (CoTS) are vulnerable to predation, though the importance and rates of predation are generally unknown. This study explores variation in the incidence and severity of injuries for Acanthaster cf. solaris from Australia's Great Barrier Reef. The major cause of such injuries is presumed to be sub-lethal predation such that the incidence of injuries may provide a proxy for overall predation and mortality rates. A total of 3846 Acanthaster cf. solaris were sampled across 19 reefs, of which 1955 (50.83%) were injured. Both the incidence and severity of injuries decreased with increasing body size. For small CoTS (<125 mm total diameter) >60% of individuals had injuries, and a mean 20.7% of arms (+/- 2.9 SE) were affected. By comparison, (<30% of large (>450 mm total diameter) CoTS had injuries, and, among those, only 8.3% of arms (+/- 1.7 SE) were injured. The incidence of injuries varied greatly among reefs but was unaffected by the regulations of local fisheries.