Coral health rapid assessment in marginal reef sites

Abstract

The Brazilian reef fauna shows high levels of endemism, with both the continental coast and oceanic islands considered as unique biogeographic provinces divided in tropical coral reefs (northern and northeast) and subtropical rocky reefs (southern). While assessments and descriptions for the tropical reefs have reported different levels of impact in different regions, the southern ones have not yet been considered. In addition to a baseline assessment of benthic cnidarian cover, we evaluated the condition of the massive coral colonies of Arraial do Cabo, southeastern Brazil. Results indicated Palythoa caribaeorum as the most abundant cnidarian in all sites followed by Millepora alcicornis, octocorals and scleractinian corals. Most Siderastrea stellata colonies assessed had filamentous algae covering a major area of their tissues and roughly one-third of Mussismilia hispida colonies were also covered by algae. Bleaching was detected in less than 5% of colonies of these species. Coral deterioration in the region is historical and includes unreported diseases and bleaching with subsequent algal settlement and succession over colonies. The lack of previous monitoring programmes on benthic organisms makes the discernment of natural and anthropogenic impacts a difficult task. The scenario described here for native corals in Arraial do Cabo requires urgent action with further experimental work on factors that contribute to the demise of the corals.