Question

fresh water algae when shifted to marine water cannot survive.why?

Answer 1

Every organism has a special features to cope with a particular kind of environment.

Marine algae has an adapting feature to cope up with high salinity conditions, they can tolerate the high salts whereas freshwater algae does not.

Freshwater algae also cannot tolerate the high tides in the oceans or sea, they get buried by wave action whereas marine algae can easily tolerate the high tide they are attached to their substratum very tightly.