Recifes potiguares frente à anomalia térmica de 2024

Abstract

Coral reefs are ecosystems of high ecological and socioeconomic importance, supporting a wide range of marine biodiversity, protecting coastal zones, and promoting activities such as fishing and tourism. However, these environments have been increasingly pressured by rising ocean temperatures and anthropogenic impacts, such as pollution, sedimentation, and eutrophication. Global climate change, associated with events like El Niño, has intensified coral bleaching and mortality, threatening the integrity of these habitats. This study assessed the impacts of the thermal anomaly related to the 2024 El Niño event on coral reefs along the Potiguar coast, focusing on the areas of Pirangi and Maracajaú in Rio Grande do Norte, Brazil. Variations in benthic substrate cover, coral health, fish assemblages, and trophic groups were analyzed, comparing the dry (summer) and rainy (winter) seasons. In Pirangi, an increase in foliose and turf algae was observed, along with a rise in hard coral cover (from 8% to 14%). In Maracajaú, high cover of bleached corals was recorded during the dry season, later replaced in the rainy season by dead corals and Palythoa, in addition to an increase in hard coral cover (from 3% to 15%). The fish assemblage in Pirangi was dominated by the Pomacentridae family in both seasons, with increased specimen abundance, whereas in Maracajaú, a greater total abundance was observed during the dry season and a slight increase in species richness during the rainy season. In both locations, herbivore-detritivore species were the predominant trophic group (e.g., Stegastes fuscus, Sparisoma sp.). In Pirangi, during the rainy season, increases in herbivore-detritivores, omnivores, and mobile invertebrate feeders were recorded, a trend not observed in Maracajaú, where mobile invertebrate feeders did not follow the same pattern. It is concluded that thermal stress triggered processes of degradation and ecological transition in the evaluated reefs, with signs of partial recovery during the rainy season. This reinforces the importance of continuous monitoring and adaptive management strategies for the conservation of these ecosystems.