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Discover the causes and effects of coral bleaching, its impact on marine ecosystems, and the urgent actions needed to protect and restore coral reefs.
Coral bleaching occurs when zooxanthellae—algae that live symbiotically within corals—expel themselves from their host coral due to environmental stress.
Because zooxanthellae provide corals with their colour, this breakdown in their symbiosis leads to corals’ paleness, and a prolonged absence of zooxanthellae in corals can result in coral death.
The zooxanthellae’s flight from corals is a response to multiple forms of coral stress. These include climate change induced ocean warming, pollution, extreme tides, and high solar irradiance. These stressors threaten important coral reef ecosystems and their health.
As early as November 1988, a report from the Coral Reef Information Network of the Philippines revealed decreases in live coral cover at up to 46% and increases in dead coral cover at up to 49%. The report suggested elevated sea temperatures as a major cause for the issue.
Coral bleaching is also critical global issue — Between 2014 and 2017, nearly 75% of the world’s tropical reefs experienced severe heat-stress that led to coral bleaching. For 30% of these reefs, the stress was fatal. This widespread bleaching highlights the urgent need to address climate change’s impacts on coral ecosystems worldwide.
Increased ocean temperatures and acidification due to climate change are arguably the most significant factors resulting in coral bleaching.
Prolonged increases in water temperature cause stress for coral polyps, resulting in their symbiotic algae, zooxanthellae, being expelled.
Increased ocean acidification hinders the production of calcium carbonate necessary for growing coral skeletons. This also triggers the expulsion of zooxanthellae.
Additionally, climate change triggers sea level rise, alters storm patterns, and affects ocean circulation. These combined effects threaten the health and diversity of coral ecosystems worldwide, underscoring the urgent need to address climate change.
Whiteness in corals may also be caused by predation or diseases.
Coral bleaching is not necessarily permanent. If stressors such as high water temperatures are reduced, zooxanthellae can once again take residence in their coral hosts.
However, bleached corals that are still alive are highly vulnerable to disease and mortality. The longer corals remain without their symbiotic zooxanthellae, the less likely they are to survive the bleaching event.
The most effective way to protect corals from bleaching is to prevent it from happening. Everyone can participate by:
Coral reefs are a vital marine ecosystem. In the North Oriental Mindoro MPA, they provide habitats, food and storm protection.
Embrace your passion for the ocean by becoming a citizen scientist during your holiday in North Oriental Mindoro, Philippines. As you explore this vibrant ecosystem, you can contribute significantly to our understanding of its precious marine life.
Learn about the key principles for being a sustainable marine traveller in Oriental Mindoro Marine Protected Areas.
Blue Alliance Philippines is committed to safeguarding marine ecosystems and improving the lives of coastal communities. Your donations are crucial for bolstering enforcement, fostering community development, advancing scientific research, and empowering local communities.
100% of your donation will go to support the work of Blue Alliance Philippines
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