Spatial Variability of Sponge Assemblages on the Wellington South Coast, New Zealand

The aim of this study was to provide baseline data for sponge biodiversity on the Wellington South Coast, New Zealand. Eighteen sites were qualitatively sampled resulting in the identification of 65 different sponge taxa. Forty-three of these species were also reported from a quantitative survey of three vertical wall sites in 8-10m depth conducted as part of a long-term monitoring study. All three sites had a similar mean number of species per quadrat, however, the percentage cover of sponges and sponge density varied significantly between sites. ANOSIM showed that all three sites were significantly different from each other (P<0.001), which is likely the result of differences in environmental conditions. The Wellington South Coast has a diverse sponge assemblage, which is atypically dominated by calcareous species of the genus Clathrina. This appears to be unusual for New Zealand, and although the reasons for this situation are unknown, we hypothesise that this situation is explained by the low levels of nutrients on the Wellington South Coast, allowing calcareous sponges to proliferate at the expense of the demosponges.