The coral reefs of the Gulf of Mexico and the Caribbean are richly diverse ecosystems of global importance. These regions contain more than 10% of the world’s reefs and are home to hundreds of species of fish, providing more than $6 billion in economic benefits through fishing, tourism and other ecosystem services. But over the last four decades, climate change and local stressors like overfishing, pollution and invasive species have taken a heavy toll. On average, living coral covers less than 10% of the surface of most reefs in the region.
Heat stress is one of the main culprits for this decline. It can cause a phenomenon called coral bleaching, in which corals expel the colored algae that provide most of their food. If the algae return, the corals may survive the ordeal. But prolonged periods of high temperatures or back-to-back bleaching events will eventually kill many corals. Since 1987, the Florida Keys alone have been affected by at least six major bleaching events, with several events spreading throughout the region.
In a new study published in Journal of Geophysical Research: Biogeosciences, Lawman et al. use climate model simulations spanning 2015 to 2100 to assess how heat stress and ocean acidification, caused by rising carbon dioxide levels, will affect corals in the Gulf of Mexico and the Caribbean. The authors also broke down the modeled temperature and acidification rates by region. They found that based on the simulation, sea surface temperatures in the area increased by 0.3°C to 0.4°C per decade during the 21st century (or 2°C to 2.8°C steadily). cumulative at the end of the century).
If these estimates prove accurate, ocean temperatures will exceed the region’s coral bleaching threshold by mid-century, indicating that heat stress will have a faster and more extreme impact on reefs compared to acidification. However, in some regions, ocean temperatures are projected to change more slowly. The authors suggest that protecting these regions as climate refugia could be prioritized. The findings could also be combined with studies focused on other coral stressors to create comprehensive regional risk maps to inform better management.
The authors conclude that, in the absence of significant and targeted mitigation efforts, the stresses of higher temperatures and ocean acidification will likely kill many existing corals in the Gulf of Mexico and the Caribbean by 2100.
Research reveals remarkable variability in coral heat tolerance
AE Lawman et al, Rates of Future Climate Change in the Gulf of Mexico and Caribbean Sea: Implications for Coral Reef Ecosystems, Journal of Geophysical Research: Biogeosciences (2022). DOI: 10.1029/2022JG006999
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