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?

Explanation

### Step-by-Step Solution:

1. **Understanding Coral Reefs**: Coral reefs are marine structures formed by the accumulation of coral polyps, which require specific environmental conditions for their growth and survival.

2. **Identifying Required Conditions**: For coral reefs to thrive, several conditions must be met:
- **High Salinity**: Coral reefs need waters with high salt concentration.
- **Low Siltation**: Minimal sedimentation is crucial, as excessive silt can smother corals.
- **Low Freshwater Inflow**: Freshwater from rivers can reduce salinity levels, which is detrimental to coral health.
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