‘Prickly problems’ on Australian reefs: comparative ecology and management of crown-of-thorns starfish and long-spined sea urchins

Context Overabundant echinoderms can dramatically alter reefs, with this problem being exemplified along Australia’s coast, with recurrent outbreaks of crown-of-thorns starfish (CoTS) (Acanthaster cf. solaris) on the Great Barrier Reef (GBR) and high densities of long-spined sea urchins (Centrostephanus rodgersii) on the eastern Great Southern Reef (GSR). Aim To foster cross-system knowledge exchange on ‘prickly problems’ across reef systems. Methods Synthesise and compare the ecology and management of CoTS and C. rodgersii, focusing on the GBR and GSR. Key results Population dynamics differ, with recurrent boom-and-bust outbreaks in CoTS, whereas C. rodgersii can increase to high-density stable populations, forming urchin barrens that last decades or more. Differences in nutritional ecology (obligate corallivore, CoTS, v. omnivore, C. rodgersii) and regeneration rate of nutritional resources are linked to population dynamics. For both species, there is evidence of effective, local, top-down active management by culling or harvesting, but large differences in funding exist (funding for GBR CoTS management is >40-fold higher than for Tasmanian urchin management). Conclusions Spatially structured management aimed at prevention is more efficient and cost effective than reactive control efforts. Implications The review emphasises the value in bridging research and sharing knowledge across parallel but largely independent research fields across tropical and temperate reefs.