What eats a cauliflower coral? An assessment of predation on the endangered temperate soft coral, Dendronepthya australis

Abstract

Temperate soft corals are found in many estuaries around the world and often form large habitats in these environments, yet the functional ecology of soft corals is poorly understood. To understand the functional role of a soft coral in temperate ecosystems, we examined the role of the endangered Dendronepthya australis cauliflower coral as habitat for fishes and invertebrates, and whether associated species used the soft coral as a food source. Using Bayesian stable isotope mixing models of δ13C and δ15N values of soft corals and a suite of potential invertebrate consumers, we found that five of eight soft-coral-Associated invertebrates were all likely to be feeding almost exclusively on the soft corals. In situ feeding experiments conducted using baited remote underwater video systems (BRUVS) with soft coral cuttings as 'bait' did not identify any larger species as consumers. Fish assemblages studied using remote underwater video systems (RUVS) were diverse in the soft coral habitat and overlapped with assemblages of both sediment and seagrass environments. These results highlighted that these soft corals have a valuable trophic role in estuarine food webs through trophic transfer of nutrients via invertebrate consumers, and that soft coral habitats are used by commercially and recreationally important fishes.