Species Richness, Diversity and Abundance of Sponge Communities in Broward County, Florida, 2000-2015

Guy Harvey Oceanographic Center Facility

Sponges (Porifera) are a major component of coral reef ecosystems. They outnumber coral species on the Florida Reef Tract and in places account for more living cover. Because coral reefs are a vital part of Florida’s economy, it is important to understand how local sponge assemblages vary over time, especially as corals have declined over the last few decades. However, detailed long-term observations of sponge assemblages (species richness, diversity and abundance) are lacking. To address this, photoquadrants were analyzed from a series of 25 transect sites off Broward County occupied between 2000 and 2015 (as part of the Broward County Marine Biological Monitoring Project) excluding 2009. Of the 94 species identified, Spirastrella coccinea was most common and was present at 21 of the 25 sites. Other common species included Niphates erecta, Amphimedon compressa and Aplysina cauliformis. Species richness increased with depth, perhaps a result of greater habitat stability in deeper water. Significant differences in sponge assemblages appeared among different reef types (colonized pavement, middle and outer reef). Although assemblages at most sites exhibited no significant change over the course of the study, those on shallow habitats did change, likely as a result of hurricanes and storms that increased sedimentation and caused some burial of sponges. Results will be compared with variations in coral assemblages at the same sites and will provide a baseline for future studies.