Most aquatic organisms can survive only within a specific ph range. an increase in the number of hydrogen ions (h+) in a lake with many aquatic organisms would cause

An increase in the number of H+ ion in the lake with many aquatic would cause cell shrinkage by the removal of water from the cell.

Explanation:

Every organism tries to maintain a constant PH inside their body to regulate the homeostasis of their body.

                     An increase in the number of H+ ion or proton in a lake will increase the osmotic pressure of the water present in the lake.As the osmotic pressure of Lake"s water is increased it will draw water out from the the cells of aquatic organism causing the cells to shrink thus decreasing the volume of the cell and if the H+ ion concentration rises at a high level cell death can occur.