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About Coral Bleaching
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- Coral bleaching refers to the whitening or loss of color in corals, which happens under two main conditions:
(i) when the population of zooxanthellae (the symbiotic algae living within coral tissues) decreases significantly, and
(ii) when the levels of photosynthetic pigments in these algae are reduced.
- Both factors disrupt the delicate balance of the coral-algae relationship, leading to a visible paling of the corals.
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Ecological causes of coral bleaching
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- Temperature (Major Cause)
- Sub aerial Exposure – Sudden exposure of reef flat corals to the atmosphere during events such as extreme low tides, ENSO-related sea level drops or tectonic uplift can potentially induce bleaching.
- Sedimentation
- Fresh Water Dilution Inorganic Nutrients (Example: ammonia and nitrate).
- Xenobiotics – Zooxanthellae loss occurs during exposure of coral to elevated concentrations of various chemical contaminants, such as Cu, herbicides and oil.
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