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

Question

Quizplus · Accepted Answer

When a fish swims from a river into an estuary, it encounters changes in the water's solute content, specifically an increase in salinity. This change can challenge the osmotic balance of the fish, as it tries to maintain a balance of water and salt in its body. This can lead to dehydration or overhydration. The other options, low oxygen content, high water flow, and temperature change, can also present physiological challenges, but they are not the greatest challenge for a fish swimming into an estuary.

A Fish Swimming into an Estuary from a River Would