Epibenthic habitats of the lower mesophotic zone off western Kangaroo Island, South Australia

Context Mesophotic temperate habitats are among the world’s most poorly studied ecosystems, yet they support a wide range of ecosystem services, including fisheries production. Aims In this study, we aimed to compare the epibenthic communities occurring on mesophotic plain v. reef habitats off the western coast of Kangaroo Island, South Australia. Methods We annotated autonomous underwater vehicle imagery collected from 2 years, using the Australian Morphospecies Catalogue to compare community structure differences. Key results Results identified that the two habitats differed greatly in structure and complexity of epibenthic communities, with greater morphospecies richness across reefs. A greater proportion of hydroids than other cnidaria was identified across reef outcrops, which is unique to temperate mesophotic reefs described globally. For mesophotic plains, model predictions showed that refining soft substrate into finer categories can be useful for predicting morphospecies counts. Conclusion The findings of this study have provided new information of the epibenthic structure of mesophotic reef and plain habitats in the Southern Ocean. Implications These baselines will be important for future integration into benthic assessment and management programs in the deep continental shelf waters of southern Australia.