A fish swimming into an estuary from a river would have which of the following as its greatest physiological challenge?
A)The high water flow would make the fish expend more energy.
B)The low oxygen content would give the fish difficulty in swimming aerobically.
C)The temperature change would stress the fish by denaturing its proteins.
D)The change in water solute content would challenge the osmotic balance of the fish.
E)The flux of nutrients washing into the estuary would give the fish difficulty in swimming aerobically.

Question

Quizplus · Accepted Answer

The change in water solute content would challenge the osmotic balance of the fish. When a fish moves from a freshwater river to a saltwater estuary, it would face the challenge of osmoregulation. In the freshwater, the fish would absorb water and lose salt while in the estuary it would lose water and absorb salt. To compensate for this, the fish must modify its physiological processes to adjust to the new environment.

A Fish Swimming into an Estuary from a River Would