What are the main threats to coral reefs?

The main threats to coral reefs include climate change and overfishing, which are significant factors contributing to their decline.

Climate change affects coral reefs primarily through increased ocean temperatures and ocean acidification. Elevated sea temperatures can lead to coral bleaching, a process where corals expel the symbiotic algae (zooxanthellae) that provide them with energy and coloration. If the temperature remains high for an extended period, the corals can die, leading to a loss of biodiversity and habitat within the reef ecosystem. Ocean acidification, resulting from increased carbon dioxide absorption, affects the ability of corals to calcify, weakening their structures and making it difficult for them to recover.

Overfishing further exacerbates the vulnerability of coral reefs. Many fish species play critical roles in the maintenance of reef ecosystems by grazing on algae and helping to regulate the overall health of the reef. When these species are overfished, algae can overtake and suffocate coral, leading to further degradation of the reef ecosystem.

In contrast, while excess nutrient runoff and natural predation, increased sedimentation, and natural disasters do pose threats to coral reefs, they are not as pivotal as the effects of climate change and overfishing. Additionally, water temperature stabilization and