What happens to fish populations as a direct result of decreasing oxygen levels due to algae die-off?

Decreasing oxygen levels due to algae die-off can significantly impact fish populations. When algae bloom and subsequently die off, the decomposition process consumes a substantial amount of dissolved oxygen in the water. This reduction in oxygen availability creates a hypoxic environment, which can be detrimental for fish and other aquatic organisms that rely on oxygen for survival.

As a result, fish populations may experience a decline. Fish are sensitive to oxygen levels; if those levels drop too low, it can lead to stress, decreased activity, and in severe cases, mortality. Species that are less tolerant to low oxygen conditions may be particularly affected, potentially leading to a decrease in their population numbers. Some fish may attempt to move to areas with better oxygen levels, but if the hypoxia affects a large area, they may not be able to escape. This combination of stress, displacement, and mortality illustrates why fish populations are likely to decline when oxygen levels decrease due to algae die-off.