Coral bleaching is a stress response of corals, in which they expel the symbiotic algae (zooxanthellae) living in their tissues. Since these algae provide corals with food through photosynthesis and give them their vibrant colors, their loss causes corals to turn white, a condition called bleaching.
Coral bleaching occurs when coral polyps expel the symbiotic algae (zooxanthellae) living inside their tissues, leading to the coral turning white. These algae are photosynthetic and normally provide energy and colour to the corals.When sea temperatures rise, zooxanthellae start producing reactive oxygen species that are toxic to corals. To protect themselves, corals expel the algae. Since the algae provide colour, their loss makes coral tissue transparent, exposing the white calcium carbonate skeleton beneath.Most bleached corals look bright white, but some may appear blue, yellow, or pink due to the presence of pigment proteins in the coral.Bleached corals are not immediately dead, but they become highly vulnerable to disease and starvation.Zooxanthellae supply up to 90% of coral’s energy. Without them, corals struggle to survive.If stressful conditions subside quickly, some corals can recover.Certain coral species can temporarily survive by feeding themselves, but in most cases, prolonged bleaching leads to starvation and death.
India’s Context
Q1. What is coral bleaching?
Coral bleaching is the process where corals lose their symbiotic algae (zooxanthellae) due to stress, turning them white and making them vulnerable to death.
Q2. What causes coral bleaching?
The major cause is rising sea temperatures, but other factors like ocean acidification, pollution, sedimentation, and excessive sunlight also contribute.
Q3. Why is coral bleaching harmful?
Bleaching weakens coral reefs, reduces biodiversity, impacts fisheries, and increases coastal vulnerability to storms and erosion.
Q4. Can corals recover from bleaching?
Yes, if stress factors are removed quickly, corals can recover. However, prolonged bleaching often leads to coral death and reef degradation.
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