Acropora tenella, a zooxanthellate coral extending to 110-m depth in the northern Coral Sea

The zooxanthellate scleractinian genus Acropora (Acroporidae) dominates many shallow-reef areas across the Indo-Pacific, but has recently been recognised as a component of deep-reef assemblages with only a few records below 60 m depth. Here, we report on Acropora tenella (Brook, 1892) growing to 110-m depth in the western Coral Sea, equal to the record for the genus and close to the maximum reported for zooxanthellate corals in Eastern Australia. The species was detected at several sites in the northern Great Barrier Reef and western Coral Sea, generally occurring as large colonies but at a low level of abundance and only below 40-m depth. We review museum holdings and other recent literature, finding the species has a much wider bathymetric and geographical distribution than previously documented. Acropora tenella is currently listed as vulnerable to extinction on the basis of a limited distribution and global population size, but we suggest that this status and that of other deep-water zooxanthellate corals may require revision in light of new data from the mesophotic zone.