Scientists studying Lake Erie have found that fish do not always flee areas affected by low oxygen. Instead, many gather along the boundaries of hypoxic zones where oxygen rich and oxygen depleted waters meet.
Researchers found that these boundaries can shift rapidly as temperature, oxygen and water conditions change. For fish, the edges may provide a narrow zone of suitable habitat while allowing them to remain close to areas with different food and environmental conditions.
The finding is important for understanding how climate change could affect fish communities in the Great Lakes. Warmer temperatures, changes in rainfall and nutrient levels can influence thermal stratification and oxygen depletion, potentially compressing the habitat available to fish.
This “habitat compression” could also affect fisheries. When fish become concentrated in smaller areas, fishing gear may encounter them more frequently, potentially making populations appear more abundant than they actually are in surveys.
The research suggests that monitoring the moving boundaries of low oxygen zones could provide important insights into changes in fish distribution, food webs and fisheries as climate conditions continue to change.