Status of Eastern Brazilian coral reefs in time of climate changes

Abstract

Brazilian reefs comprise the largest and the richest reefs of the Southwestern Atlantic Ocean. Indicators of reef vitality reveal that reefs located less than 5 km from the coastline, the inshore reefs, are in poorer conditions than those located more than 5 km off the coast, the offshore reefs. The inshore reefs are the most impacted by the effects of eutrophic waters associated with sewage pollution, high sedimentation rates and water turbidity, and the most exposed to the effects of bleaching and infectious diseases. From 1998 to 2005, long-term sea water thermal anomaly events, equal or higher than 1oC, were responsible for more than 30% of bleached corals in the inshore reefs. In the offshore reefs of the Abrolhos area, bleaching was milder, but the reefs are strongly threatened by the incidence of diseases that have escalated in prevalence from negligible to alarmingly high levels in recent years. Although bleaching and coral disease have not yet caused mass mortality in the Brazilian reefs, these natural disturbances associated with the effects of global climate changes and human-induced activities, could lead the reefs to higher levels of degradation.