Prediction of lake water temperature, dissolved oxygen, and fish habitat under changing climate

We applied a three-dimensional lake water quality model to investigate the influence of local meteorological conditions on fish habitat under one historical and two future climate change scenarios. Compared to the historical normal climate scenario, the averaged surface water temperature increases up to 4 °C and the dissolved oxygen concentration is 1 mgL⁻¹ less during the ice-free seasons under the future climate scenarios. The stratification periods expand up to 23% (46 days), thermocline depths increase 49%, and the onset of anoxia occurs 4 weeks earlier under the future climate scenarios. The dissolved oxygen concentrations and water temperatures are used as the key water quality parameters to investigate the temporal and spatial variabilities of fish habitat. The good growth, restricted growth, and lethal habitats for the coolwater fish change up to 14% of the total lake volume. Compared to the historical normal climate scenario, on average, the lake total volume for good growth, restricted growth, and lethal habitat of coolwater fish change +16, −18, and +85%, respectively. The most significant (70%) changes in lethal habitat for coolwater fish occurs in the upper 5 m of the water column. During summer, a modest increase of lethal habitat for coolwater fish (8% of total lake volume) has a pronounced impact on the good growth habitat. The prediction of spatial locations and time periods of potential fish habitats during stressed or lethal environmental conditions is becoming increasingly important for managing fish habitats under changing climate.