Over the decades local and global ice ages have lowered sea levels. as a result, there is often a decline in marine diversity due to a) migration of bottom feeders into the region. eliminate b) changes in the temperature and salinity of water. c) migration of fresh water fish to places near the mouths of rivers. d) formation of breeding grounds for various species in the shallow waters.

Option D

Explanation:

With lowering sea and ocean level, the temperature and salinity of the water is widely affected. Earlier when the sea or ocean level was high, the species such as turtle used to make their breeding grounds in the coastal sandy area, however reducing sea level has caused a defective approach of forming breeding grounds in shallow waters where the temperature and salinity requirement is not adequate and hence the reproductive efficiency of all marine species reduces.  

This climate change threatens the stability of marine species population in future.  

Hence, option D is correct

thinking it would be d not too sure but i think it's right