The Sponge Gardens of Ningaloo Reef, Western Australia

Abstract

Preliminary results from biodiversity surveys in the deeper waters of Ningaloo Marine Park, Western Australia revealed that while much of the area is composed of sediments and rhodolith fields with low densities of macroepibenthos, locally dense and extensive filter feeding communities exist. They were distinctly dominated by demosponges, both in biomass and diversity. A subsample of dominant taxa determined by fresh weight yielded 155 different demosponge species from over 350 transects between 18-102 m depth. Data from three successive years of sampling indicated that only a few species were ubiquitous, suggesting that as minor species are identified the cumulative species list will significantly exceed the present species record. This implies greatly enhanced biodiversity values associated with Ningaloo Marine Park, complementing records attributed to the shallow coral reef environment. The richness of the observed filter feeding communities adds additional weight to the increasing perception of Australia as a global hotspot for Porifera biodiversity.