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.

Question

Quizplus · Accepted Answer

When a fish swims into an estuary from a river, the change in water solute content would challenge the osmotic balance of the fish, as the salt concentration in the estuary is higher than that of the river. This would result in a risk of dehydration, as the fish would have to actively maintain its osmotic balance by retaining water in its body. The other options may also pose some physiological challenge, but the change in water solute content would be the primary challenge for the fish.

A Fish Swimming into an Estuary from a River Would