The variability in marine salinity between habitats will have an impact on the fish living there as the change in the salt level can affect fish life cycle. It depends on the salt tolerance levels of fish. Fishes which adapt to the change salt conditions will survive.
All the cells in a person's body have the same DNA and the same genes. However, the difference between cells in different tissues and organs is that the "expression" of the genes differs between cells. Expression means that the message from the DNA is being copied and made into protein.
