Idiosyncratic Recovery Patterns in Coral Reefs of the Maldives Following Climate Disturbance

Abstract

The severe heatwave that occurred in April–May 2016 caused widespread bleaching and mortality in the Maldivian coral reefs. In this study, the main factors that influenced coral recovery were investigated, that is, reef typology and exposure (ocean vs. lagoon) and depth (5 m vs. 10 m). Field surveys were conducted in 2019 and 2021 on 26 Maldivian reefs through photographic samplings. Changes in coral community structure and composition were analysed using the percent cover of the dominant coral families in the Maldives (Acroporidae, Pocilloporidae, and Poritidae) and of a number of benthic categories (encrusting corals, soft-bodied organisms, abiotic components). Following the climate disturbance, most of the reefs were still dominated by abiotic components (mainly coral rubble and dead corals) after 5 years, although a slight recovery in hard coral cover was registered. Ocean reefs, dominated by massive Poritidae corals, exhibited a higher recovery capacity than lagoon reefs. Lagoon reefs displayed a higher coral mortality and spatial variability in their recovery patterns and in the coral community composition. Encrusting corals and soft-bodied organisms played a major role in the reef regeneration. The predicted increase in heatwaves frequency due to climate change makes long-term monitoring mandatory to tackle coral reefs' recovery potential and to evaluate their resilience to global warming. Photographic sampling represents a cost-effective methodology to monitor coral communities regularly and objectively evaluate changes in the abundance of the main reef components.