Why are coral reefs not found in the regions from West Bengal to Andhra Pradesh,but are found in Tamil Nadu and on the east coast of India?

(N/A) Coral reefs require specific environmental conditions to thrive,including clear,warm,tropical waters,high salinity,and low levels of sedimentation or siltation.
In the regions from West Bengal to Andhra Pradesh,the presence of major river systems (like the Ganges,Mahanadi,Godavari,and Krishna) leads to a high influx of freshwater and significant siltation,which increases turbidity and reduces light penetration,making it unsuitable for coral growth.
Conversely,the coastal regions of Tamil Nadu and parts of the Gulf of Mannar provide the necessary stable,high-salinity,and clear-water environments that support the development of coral reefs.