Great Barrier Reef has recorded its largest Coral Bleach

Source: IT

Context: The Great Barrier Reef has recorded its largest annual coral cover decline in nearly 40 years, driven by severe coral bleaching, cyclones, and crown-of-thorns starfish outbreaks.

About Great Barrier Reef has recorded its largest Coral Bleach:

• What is Coral Bleaching?

• A stress response in corals when symbiotic algae (zooxanthellae) are expelled from coral tissues. Loss of algae removes the coral’s main food source and colour, leaving it pale or white. Bleaching does not always kill coral, but prolonged stress can lead to mortality.

• A stress response in corals when symbiotic algae (zooxanthellae) are expelled from coral tissues.

• Loss of algae removes the coral’s main food source and colour, leaving it pale or white.

• Bleaching does not always kill coral, but prolonged stress can lead to mortality.

• Causes of Coral Bleaching:

• Increased Sea Temperatures – Often from climate change and El Niño events. Pollution & Runoff – Nutrient-rich runoff from agriculture promotes harmful algal blooms and reduces water quality. Overexposure to Sunlight – High solar irradiance during heat events. Extreme Low Tides – Exposes shallow corals to air and heat stress. Cold Stress Events – Rare but possible, such as Florida Keys (2010).

• Increased Sea Temperatures – Often from climate change and El Niño events.

• Pollution & Runoff – Nutrient-rich runoff from agriculture promotes harmful algal blooms and reduces water quality.

• Overexposure to Sunlight – High solar irradiance during heat events.

• Extreme Low Tides – Exposes shallow corals to air and heat stress.

• Cold Stress Events – Rare but possible, such as Florida Keys (2010).

• Process of Coral Bleaching:

• Healthy State – Coral and algae (zooxanthellae) coexist in a symbiotic relationship, with algae providing most of the coral’s energy and colour through photosynthesis. Stress Trigger – Environmental changes like warmer sea temperatures, pollution, or extreme sunlight disturb this balance, causing physiological stress to the coral. Algae Expulsion – In response to stress, coral ejects the algae from its tissues, losing its primary food source and vibrant colour. Bleached Stage – The coral’s transparent tissue exposes its white skeleton, leaving it weak, energy-deprived, and prone to disease. Outcome – If stress is short-lived, algae return and the coral recovers; if prolonged, the coral dies and reef ecosystems degrade.

• Healthy State – Coral and algae (zooxanthellae) coexist in a symbiotic relationship, with algae providing most of the coral’s energy and colour through photosynthesis.

• Stress Trigger – Environmental changes like warmer sea temperatures, pollution, or extreme sunlight disturb this balance, causing physiological stress to the coral.

• Algae Expulsion – In response to stress, coral ejects the algae from its tissues, losing its primary food source and vibrant colour.

• Bleached Stage – The coral’s transparent tissue exposes its white skeleton, leaving it weak, energy-deprived, and prone to disease.

• Outcome – If stress is short-lived, algae return and the coral recovers; if prolonged, the coral dies and reef ecosystems degrade.

• Implications:

• Ecosystem Collapse – Coral reefs host ~25% of marine species. Economic Loss – Impacts fishing, coastal protection, and tourism. Biodiversity Decline – Loss of breeding grounds for marine life. Climate Feedback Loop – Dead reefs store less carbon and lose their role as natural wave barriers.

• Ecosystem Collapse – Coral reefs host ~25% of marine species.

• Economic Loss – Impacts fishing, coastal protection, and tourism.

• Biodiversity Decline – Loss of breeding grounds for marine life.

• Climate Feedback Loop – Dead reefs store less carbon and lose their role as natural wave barriers.