Echinoderms of the Houtman Abrolhos Islands, Western Australia and their relationship to the Leeuwin Current

The Houtman Abrolhos Islands (28°18’–29°S, 113°36’–114°E), lying 65–90 km off the mid west coast of Western Australia are the southernmost coral reefs in the Indian Ocean. They are influenced by the warm Leeuwin Current during autumn and winter and by cooler water during the summer resulting in a juxtaposition of coral reefs and kelp beds which is reflected in the composition of the echinoderm fauna. Sixty three percent of the 172 species of echinoderms are tropical species, 14% are southern Australian temperate species and 21% are endemic to the west coast of Australia but no species is confined to the islands.