With or without nutrients, sponges are boring: No effect of inorganic nutrients on clionaid sponge bioerosion of carbonate substrate.

ABSTRACT

Sponge bioerosion is an important process on many carbonate reef ecosystems. Eutrophication has been linked with an increase in boring sponge abundance and biomass in coral reefs, yet the impacts on sponge bioerosion rates remain largely unexplored within oyster reef communities. The present study evaluated the impacts of nitrate and phosphate addition on the bioerosion of Cliona celata inhabiting carbonate substrates in the subtropical southeastern U.S. Using in situ and aquarium manipulations, sponge bioerosion rates were compared among control and nutrient addition treatments in three experiments. Overall, there were no differences in loss of calcium carbonate substrate among treatments in any of the experiments, though very high rates of bioerosion (up to 0.11 g CaCO3 day-1) were observed in the field experiments. Future research should consider the impacts of both inorganic and organic nutrient loading to fully understand the impacts of eutrophication on boring sponge ecology in subtropical oyster reefs.