A quantitative assessment of the status of benthic communities on US Atlantic coral reefs using a novel standardized approach

Abstract

As coral reefs decline globally, the need for an objective approach to quantify the status and trends of corals has become increasingly important. Empirical data on predisturbance conditions are rare, and integrating data from multiple and disparate survey designs and methods can be analytically challenging. Our goal was to conduct a holistic, data-driven evaluation of the status of corals and benthic communities in US Atlantic coral reef jurisdictions: Florida, Flower Garden Banks, Puerto Rico, and the US Virgin Islands. A quantitative approach based upon standardized data was used to compare the change in multiple indicators of coral condition (hard coral, macroalgae, and crustose coralline algae cover, coral density, and old mortality) from historic to current conditions in each geographic region. For each indicator, historic, reference baseline conditions from long-term monitoring data or literature data were first identified, reviewed, and classified on a categorical scale from Very Good to Critical by regional experts to account for condition changes that pre-dated current monitoring data. A reference-centering approach then allowed for categorization of statistical changes from historic to current conditions on the same scale to produce results that could be communicated to a broad audience. Our findings show continued declines for multiple indicators in all regions except Flower Garden Banks, illustrate particularly dire declines from regions that had been impacted by Stony Coral Tissue Loss Disease at the most recent monitoring included in this study, and demonstrate the increasingly critical need for effective coral reef conservation.