Short-term temporal variability in a temperate sponge assemblage

Abstract

Despite the importance of sponges in marine benthic communities, still little is known about patterns of natural temporal variability, which is important for developing suitable management and monitoring strategies. Here, we examined the temporal variation of sponge assemblages on the Wellington South Coast in New Zealand over a 2-year period. Subtidal monitoring stations were established at three sites separated by a maximum distance of approximately 6 km. We found significant differences in sponge abundance and assemblage composition between sites, and also between seasons; however, there were no significant differences between the 2 years for a given season, suggesting the presence of cyclical seasonal variation. Over 60 % of the spatio-temporal assemblage variation could be explained by just eight sponge species, demonstrating the importance of just a few dominant species in driving assemblage composition patterns. Furthermore, the temporal changes were primarily driven by calcareous sponge species. Our results demonstrate the dynamic but cyclical nature of temperate sponge assemblages, which are correlated with seasonal temperature changes.