Coral Reef Health and Status

Abstract

To prioritize ecologically resilient reefs for conservation action, we evaluated the sites surveyed in the Northeast Madagascar Marine RAP using resilience assessment methods developed by IUCN and CORDIO East Africa. Overall the region showed high coral cover (mean of 48%), and coral populations that spanned the expected size range for the genus in question, including large, mature colonies. The common occurrence of large colonies suggests that there has been no catastrophic mortality in the past few decades. Coral recruitment was present, but relatively low. Even after an extended heating event that ended immediately preceding the survey, coral bleaching was relatively low, showing a mean [approximately]5% of colonies affected. This, and the low impact detected from the 1998 mass bleaching event, suggests that the corals in this region have largely resisted the negative effects of heating events, and supports the hypothesis that these reefs are thermally resistant. In general, the northern three locations (Ambodivahibe, Nosy Ankao, Loky Bay) showed greater coral cover, larger corals and fewer bleached colonies than the southern two sites (Andravina, and Vohemar). Coral recruitment was highest on the northern and southern extremes, in Ambodivahibe and Vohemar, though overall was comparatively low. The generally intact structure of the reefs and apparent resistance to coral bleaching suggests that the region is a priority for conservation. We recommend conservation actions to enhance coral recruitment, a key factor for ecological resilience, through the targeted restriction of fishing pressure and watershed management to limit/reduce sedimentation.