The answer is Climate change. It will take decades for the
coral reef to recover from the catastrophic climatic changes including El Nino
in 1997-98. Climate Change is the main and undeniable threats to the loss of
the corals. It has negative effects on coral populations in some ways. This
includes the Color Bleaching, Coral Disease, and Ocean Acidification.
In shallow water, there is more sunlight to keep the organisms warm and more oxygen.