Impacts of selective feeding of crown-of-thorns starfish on the coral community in the South China Sea

Abstract

Context Crown-of-thorns starfish (Acanthaster spp., hereafter COTS), the most destructive predator of corals, selectively consume specific corals. However, their feeding selectivity varies among reef regions and differs from their feeding preferences in laboratory experiments. Aims In this study, the impacts of selective feeding of Acanthaster sp. on the coral community in the South China Sea were explored. Methods COTS predation on 701 coral colonies and 24 coral genera during 2018−2019 was evaluated. Key results Montipora had a greater scar cover (57%) than did Pocillopora (27%) because of COTS predation. Additionally, the relative abundance of encrusting Montipora (heat-tolerant corals) decreased from 40 to 14%, whereas that of branching Pocillopora (less heat-tolerant corals) increased from 40 to 60%. Moreover, the rare genera Millepora and Astreopora had the greatest scar cover (from 78 to ~100%) and feeding electivity values (from 0.66 to ~0.98), and were thus positively selected by COTS for predation. Further regional comparisons showed four types of feeding selection worldwide. Conclusions Less heat-tolerant coral became predominant in the coral community owing to selective feeding of COTS. COTS could consume rare, less-preferred corals by changing feeding selections. Implications These findings suggest that COTS not only directly consume coral individuals but also indirectly change the coral community composition, which is potentially related to the vulnerability of the coral community to global warming.