IN SITU DOM Removal And Nutrient Cycling By Dominant Emergent Sponges In The Florida Keys

Very few studies have asked if and how coexisting sponges and their symbiotic microbial communities partition nutrients. To address this question, an artificial reef was set up off the coast of the Florida Keys using dominant emergent sponges found in the Caribbean and Florida Keys. Water samples were collected using Vacusip, samples were filtered with a 0.2 µm supor filter then processed for dissolved nutrients using fluorescence dissolved organic matter (fDOM), total dissolved nitrogen, and dissolved organic carbon. This is the first application of fDOM analysis to sponges. This study found that the microbial abundance (i.e., the commonly used high and low microbial abundance classification) was not an effective indicator for the way in which nutrients are processed by these sponge species. Additionally, the use of fDOM analysis indicated nuance in DOM utilization across species with differential consumption of fDOM components across sponge species. In summary, a combination of sponge species identity and the composition of the symbiotic microbial community members (e.g., presence of photosymbionts) explains the most variation in nutrient processing. These results provide the first support for resource partitioning of dissolved nutrients across coexisting sponge species and provide support for the evolutionary importance of microbial communities in sponges.