Depth distribution and abundance of benthic organisms and fishes at the subtropical Kermadec Islands

Abstract

Abstract Subtidal areas of the Kermadec Islands have not previously been described; samples from a bay at Raoul Island are discussed here. Abundances and percentage cover of benthic organisms were assessed from the high intertidal to 20 m depth using quadrat sampling. Fish abundances were assessed subtidally by random transects in shallow (3–6 m deep) and deep (14–20 m) areas of the reef. Hard corals occurred at 2–18 m depths at densities of 5 colonies per m2, but colonies were generally small. Soft coral colonies occurred at similar densities, but were confined to depths of 5–13 m. The mean percentage cover of corals did not exceed 20% at any one depth, and coral reefs did not occur. Fucalean and laminarian algae were not seen. The most abundant algae were foliose and filamentous species, and encrusting red algae. These covered over 80% of the reef at some depths. Grazing invertebrates were not abundant. Echinoids were found primarily in shallow water, reaching a density of 5 per m2 at 5 m depth. The mos...