Assessment of coral cover on Maldivian reefs after the 1998 bleaching event and 2004 tsunami

Abstract

Percent coral cover is examined from a geographically diverse set of lagoonal, shallow reefs in the Maldives from 7[degree]N to 1[degree]S in surveys conducted in 2009. Data collected by the National Coral Reef Monitoring Survey (NCRMS) of the Maldivian government's Marine Research Centre (MRC) provided an historical, along with other outside agency studies, for assessing the recovery of Maldivian coral reefs in the past 12 years to coral bleaching and a tsunami. Coral cover at study sites in the northern Haa Dhaalu Atoll was nearly 0% after the 1998 bleaching event. Subsequent reef recovery was slow with coral cover only achieving 3-5% in 2005. In 2009, coral cover ranged from 14%-29%. This was collectively the lowest coral cover for all the atolls surveyed. The shallow reefs of study sites in Ari Atoll, in the central part of the Maldives, exhibited exceptional resilience. In 2005, most of these reefs had coral cover <11%. Fesdhoo reef exhibited exceptional resilience since the bleaching recovering to 10% coral cover in 2000 and then by 2005 >30% coral cover. In 2009, it was among the most luxuriant reefs surveyed with [approximately]65% coral cover. After the 1998 bleaching, the study reefs at Addu-Gaafu Alifu (AGA) Atoll in the southern hemisphere still had some living coral. AGA Atoll had the greatest recovery of live coral cover in sites distant from anthropogenic influences. The Vilingili reef is of particular note as it had only [approximately]4% coral cover in 1998, increasing to 13% in 2002. In 2009, in spite of its proximity to the development of resort water bungalows the coral cover had increased to 55%. There is considerable variation in the recovery among reefs and among habitats within reefs.