Variability in Coral Recruitment Along the Southeast Florida Reef Tract

Guy Harvey Oceanographic Center Facility

As Florida’s scleractinian coral populations continue to decline, quantifying rates of coral recruitment and juvenile survivorship plays a critical role in developing effective conservation strategies. Previous research suggests that corals of the Florida Reef Tract (FRT) have been experiencing recruitment failure. Recruitment in this region is being outpaced by mortality, resulting in population declines in many coral species. Identifying the species most likely to recruit to Florida reefs and the locations receiving high numbers of recruits is crucial for managing decreasing populations. However, the current species distribution of recruits is unknown, the interannual and spatial variation in recruitment is undescribed, and a study examining the FRT simultaneously has not been conducted. In a collaborative effort, researchers from the Florida Fish and Wildlife Commission and Nova Southeastern University are quantifying recruitment of juvenile scleractinian and octocorals in southeast Florida and the Florida Keys from 2015 through 2017. This portion of the study focuses on 12 long-term monitoring sites off the coasts of Broward and Miami-Dade counties. Utilizing sites for which long-term adult population datasets exist allows for direct comparison of adult and juvenile populations. At each site, thirty-two 0.25m2 quadrats were established and surveyed for scleractinian corals under 40mm in diameter and octocorals under 40mm in height. Next to each quadrat, a 225cm2 grooved terracotta settlement tile was deployed and retrieved after one year. Our results from the first year of in situ juvenile censuses suggest that octocorals are recruiting to southeast Florida’s reef tract more frequently than scleractinian corals. Recruitment to tiles was extremely variable, with brooding scleractinian species dominated tiles in some locations and octocorals dominated tiles in others. In sum, completion of this study will inform reef management and restoration efforts in Southeastern Florida by identifying “recruitment hotspots”, as well as identifying those sites and species having limited ability to recover through natural recruitment processes.