Saúde dos corais Siderastrea stellata e Montastraea cavernosa e seus preditores ambientais em recifes tropicais costeiros e oceânicos

Abstract

The increase in frequency and severity of coral bleaching events due to climate change threatens reefs worldwide. In the South-Atlantic Ocean, corals seem to be more resistant and resilient to thermal stresses, which is probably explained by theses corals’ adaptation to the marginal conditions found in many different Brazilian reefs. Assessing the variation in the health condition of these corals and how they relate to natural environmental conditions from the reef can help us understand which drivers influence coral health and how the environment can shape resistance and resilience under climate change. For about two years we monitored the health condition of colonies of Siderastrea stellata, which is the dominant species in shallow reefs (up to 3m), and Montastraea cavernosa, the dominant species in deeper reefs (up to 30m), using 3D models created by photogrammetry, through which we evaluated and measured the percentage of each health indicator in each colony. Our monitoring was conducted on the coast of Rio Grande do Norte, NE Brazil and at Fernando de Noronha, an oceanic island off NE Brazilian coast. We compiled satellite data regarding Marine Heat Waves (MHW) and light attenuation coefficient (KD) and associated its variation with the coral colonies’ health profile observed in the study. Environmental drivers were different between coastal and oceanic sites and turbidity was more relevant on coastal shallow reefs. On oceanic shallow reefs, corals are under greater influence of local dynamics. The coral S. stellata, in shallow and less stable reefs, showed greater health variation than M. cavernosa, in deeper reefs with more stable environmental conditions. The main driver causing coral health fluctuation was marine heat waves, which shows us that Brazilian corals are well adapted to local adverse conditions, yet susceptible to the effects of global changes.