What is coral bleaching, and what are its main causes? Also, evaluate the role of marine protected areas (MPAs) in the conservation of coral reefs.

Coral Bleaching and Causes Coral Bleaching refers to whitening of corals, as they expel the zooxanthalae from their polyps, leading to loss of autotrophic algae and its colour providing capabilities. Causes 1) Heating of oceans - corals are sensitive to temperature changes. 2) Zoonotic viruses => invasion of coral polyps and ending the symbiotic relationship. 3) Salinity changes. 4) Thermal & chemical pollution => discharge of heated sewage water, chemical run offs etc. 5) Oil spills => coats the reef and leads to death of algae.

Role of Marine Protected Areas Positives 1) Provides sanctuaries for uninterrupted coral restoration => coral bleaching can reverse itself over time. 2) Prevention from pollution and shipping waste. 3) Scientific application for artificial coral reef generations. Eg: Mineral Accretion Technology. 4) Microcosm of safe coral reefs. Limitations 1) Does not tackle the global climatic heating of marine protected areas. 2) Weak implementation and monitoring mechanisms. 3) Ocean and reef structures have ecosystemic linkages => MPA's cannot be cut off from open ocean changes.