Coral cover on Brazil’s Abrolhos reefs has fallen by approximately 15% [1] over the past 18 years.
As the most biodiverse coral ecosystem in the South Atlantic, the decline of these reefs threatens the broader marine stability of the Brazilian coast. The loss of coral architecture reduces critical habitats for countless fish and invertebrate species, potentially disrupting local fisheries and ecological balances.
Researchers in Rio de Janeiro, including marine biologist Rodrigo Leao de Moura, tracked the decline in an 18-year study ending in 2024 [1]. The findings indicate that the degradation is driven by intensified marine heatwaves linked to climate change and other human activities [1].
These heatwaves trigger bleaching events, a process where corals expel the symbiotic algae living in their tissues. This loss of algae deprives the coral of its primary energy source and color, leaving the white calcium carbonate skeleton exposed.
"Marine heatwaves linked to climate change have intensified so-called bleaching events where corals expel the algae that call them home, which permanently undermines coral health," Moura said [1].
While some reefs can recover from isolated bleaching events, the increasing frequency and intensity of these thermal anomalies prevent the ecosystem from regenerating. The Abrolhos reefs serve as a critical biological reservoir for the region, and their continued shrinkage suggests a growing vulnerability to rising ocean temperatures [1].
Scientists said that the combination of global warming and localized human pressures creates a compounding effect. This stress makes the corals less resilient to the natural fluctuations of the South Atlantic currents, a factor that historically helped the region maintain its high biodiversity [1].
“Coral cover on Brazil’s Abrolhos reefs has fallen by approximately 15% over the past 18 years.”
The decline of the Abrolhos reefs signals that even the most diverse and resilient ecosystems in the South Atlantic are not immune to global thermal stress. Because these reefs act as a primary source of biodiversity for the Brazilian coast, their degradation could lead to a cascade of species loss, impacting everything from larval dispersal to the commercial viability of regional fishing industries.
