Results of incurrent/excurrent water samples taken from three sponge species from the Florida Keys (USA) over two or three days using a modified version of the vacuSIP in January 2022

Sponges are sessile filter-feeders that can process vast amounts of water and are known to influence the chemistry of the surrounding seawater. There has been limited work in understanding how sponges alter dissolved and particulate nutrients on coral reefs, but work is even further limited in understanding if and how sponges vary in how they process nutrients. Sponges may occasionally arrest pumping or there may be changes in which nutrients are removed or added as the water is processed by the sponge and its microbial symbiotic community. This work provides an initial examination of three common sponges in Caribbean reefs and how they alter their processing of dissolved and particulate nutrients over multiple days.

Incurrent and excurrent seawater samples were collected for each of the three sponge species and processed for: inorganic nutrients, total organic carbon and total nitrogen, targeted metabolomics, and particulate matter by flow cytometry. Sponges were sampled from Looe Key reef in the southern Florida Keys. We found that two species, both of which are high microbial abundance sponges, Verongula rigida and the barrel sponge, Xestospongia muta, were fairly consistent in dissolved nutrient fluxes across individual sponges and across days. In contrast, the low microbial abundance sponge, Niphates digitalis, was highly variable across individuals and days. These results provide additional support for the large impact that sponges have in the dissolved nutrient profile on coral reefs and provide support for a species-specific impact. These results have implications for better understanding the influence of the sponge community on coral reef nutrient dynamics.