Calibration of the Biological Condition Gradient (BCG) for Florida’s Coral Reef: Phase 2

This project updated the Florida Biological Condition Gradient (BCG) model with recent data, held virtual training sessions for managers and stakeholders, investigated BCG differences between monitoring programs, and conducted a spatiotemporal analysis of the BCG to investigate broader patterns of reef condition. Three training webinars were held for reef managers and assessment practitioners to facilitate application of the BCG model for new samples. The webinars provided an overview of the BCG, explained data management and preparation, and demonstrated data input into the BCG model calculation tool.
 

NCRMP, DRM, and CREMP reef data collected since the BCG calibration project were compiled, formatted, and aggregated with existing BCG model data. Combining all monitoring program data into one analysis created artifacts due to differences in site selection, survey locations, methodology, unequal sampling effort, sampling different times of year, and differences in metrics collected. When programs were analyzed separately, spatiotemporal patterns emerged in multiple datasets.
 

Differences between strata scores were evident in all programs indicating that the Mid Channel reefs and Offshore patch reef were in better condition than the forereef and inshore sites. The randomized surveys performed better at detecting temporal declines. CREMP BCG scores were stable over time but varied significantly by strata. DRM and NCRMP had noticeable increasing BCG scores between 2021-2024 across all strata coinciding with the SCTLD endemism and the 4th global bleaching event. The Dry Tortugas had the lowest historical scores of any region but, in the last few years BCG scores climbed significantly, indicating measurable reef condition decline. The declining BCG scores suggest that the frequency of stressors is outpacing the capacity of the reef to recover naturally. We provide a list of management recommendations including standardizing randomized monitoring surveys by adding benthic cover to DRM and conducting NCRMP annually to create the most robust holistic monitoring dataset that could be used by all. We provide several recommendations on maintaining and continued development of the BCG model.