Climatic Eutrophication: Implications for lake systems through snowmelt timing
Cultural eutrophication, the process whereby lake ecosystems are enriched through the addition of chemical nutrients from human activity run-off, has long been known to result in a decrease in aquatic health. Using long-term temperature records in Lake Tahoe, CA-NV, combined with numerical models for future climate change scenarios, we have found that a warming climate can similarly accelerate the negative effects of nutrient enrichment on lakes, giving rise to ‘climatic eutrophication’. ‘Climatic eutrophication’ refers to eutrophication that is driven by climatic influences that change physical, geochemical, or biological processes in lakes directly, initiating or accelerating the eutrophication process under nutrient conditions that, in the absence of the climatic forcings, would not lead to eutrophication. In regions where the hydrologic cycle is dominated by snowmelt in the spring, climate change will result in changing trends in deep water renewal and corresponding dissolved-oxygen concentrations. These changes are partly the result of increased stratification and warming temperatures put also a shift in the timing of snowmelt. These changes at depth are subsequently driving sediment-water chemical equilibria in ways that will increase lake nutrient loadings from bottom sediments. Such processes can affect lake conditions even in systems where anthropogenic nutrient inputs have been limited or reversed. Thus, the potential for climatic eutrophication has important implications for long term water supply and aquatic ecosystem health. In a warming climate, eutrophication is no longer a local water pollution problem, but is one that is driven by large scale processes and affects lakes and watersheds on regional and global scales.
Host: Georgiy Kirillin