Porifera (sponges) of Mermaid, Scott and Seringapatam Reefs, north Western Australia

Abstract

A quantitative survey documenting the diversity and abundance of sponges at Mermaid, Scott and Seringapatam Reefs, north Western Australia, was conducted in September 2006. Four reef habitats (fore reef slope, channel, lagoon and intertidal reef flat) were surveyed by recording numbers of sponge individuals on replicate transects, providing baseline data of sponge species present and their abundance. In total 132 sponge species were recorded from these reefs. The majority of the species found (79) were unique to one of the reefs, with only 14 species found at all three reefs. A clear difference in the composition of the sponge assemblages between Mermaid and Scott Reefs was detected, which appears to be strongly influenced by the presence of infrequently recorded (rare) species. Intertidal reef flat habitats had lower species richness than subtidal habitats (<3 species at intertidal stations compared to between 6-21 species at subtidal stations). Channels were distinct from other subtidal habitats and were characterized by high abundances of a few common species. Over half of the species found in the study were rare with 56% having five or fewer individuals recorded from all locations in the study. This is the first documentation of the sponge fauna from these reefs and only the second study to date to examine the sponges found on the oceanic reefs off north Western Australia.