Eutrophication is a process by which a body of water becomes enriched with nutrients, leading to an increase in aquatic plant and algae growth. This process is a concern for high mountain lakes, as they are often considered to be some of the most pristine and sensitive ecosystems on the planet.
Creator: © Santiago Urquijo | Credit: Getty Images
In addition, Eutrophication is a process that can have significant negative impacts on high mountain lakes. This process is driven by human activity such as agricultural runoff and sewage discharge and also by natural processes such as melting of glaciers and snowfields. The Millenium Ecosystem Assessment (MA) found that human activities have resulted in the near doubling of nitrogen and tripling of phosphorus flows to the environment when compared to natural values.
Cause of Eutrophication
There are several ways in which high mountain lakes can become eutrophic.
Human Activity
One common cause is human activity, such as agricultural runoff and sewage discharge (Schindler & Likens, 1975). Nutrients from these sources can wash into nearby lakes and rivers, leading to an increase in plant and algae growth. Climate change can also contribute to eutrophication in high mountain lakes by altering precipitation patterns and increasing the frequency of extreme weather events, which can lead to increased runoff and erosion.
Natural Processes
Another way high mountain lakes can become eutrophic is through natural processes. For example, glaciers and snowfields can release large amounts of nutrients as they melt, leading to an increase in plant and algae growth in nearby lakes (Carignan & Kalff, 2002). Additionally, high mountain lakes are often located in areas with low precipitation and high evaporation, which can lead to the accumulation of nutrients over time.
Climate Change
Studies suggested that climate change played a significant role in the eutrophication in the of high mountain lake. Increased temperature, changed precipitation pattern and wind-induced hydrodynamic fluctuations in the summer season were suggested to make a major contribution to the accelerated eutrophication. Researches showed that the local temperature and precipitation changes were closely linked to the large-scale atmospheric circulation, which opens the door for the method to be applied in other regions without local climatic information(Lu et. al., 2019).
By investigating the potential impacts of climatic factors affecting water eutrophication, (Nazari-Sharabian et. al, 2018) suggested the impacts of temperature and precipitation in new scenario:
Temperature is an important environmental factor that influences chemical and physical properties in water ecosystems such as pH, salinity, solubility, and diffusion rates, and can consequently affect water eutrophication potential. Air temperature and temperature in water bodies are in close equilibrium. Hence one of the immediate reactions to climate change is expected to be alterations in river and lake water temperatures. When water temperature and nutrient concentrations increase, algae growth is stimulated, leading to water eutrophication and algal blooms.
The change in hydrological regimes is also a consequence of climate change. In areas with projected higher precipitation, it is possible that intense extreme precipitation events will occur and cause more erosion and resuspension of sediments, ultimately resulting in higher concentrations of sediments and nutrients in receiving water bodies. Furthermore, these extreme events will increase contaminant discharge and affect non-point pollution by mobilizing them over land and increasing nutrient concentrations in receiving water bodies, consequently degrading water quality.
Negative consequences
Eutrophication in high mountain lakes can have a number of negative consequences. One of the most significant is the loss of biodiversity, as the increased plant and algae growth can outcompete native species for resources. Additionally, eutrophication can lead to changes in water chemistry and temperature, which can also harm native species (Schindler et al., 2008).
Mitigation
In order to mitigate eutrophication in high mountain lakes, a variety of strategies can be employed. One effective approach is to reduce nutrient inputs through better land use practices and sewage treatment. To mitigate eutrophication it is important to reduce nutrient inputs through better land use practices and sewage treatment, and restore natural water flow patterns and increase the size of riparian zones. Additionally, restoring natural water flow patterns can help to reduce nutrient inputs.
If lake is already at eutrophic state, a management plan for reducing eutrophication is urgently needed that acts on external loads (namely, on WWTP) and, as much as it is possible, on internal P release from sediments (e.g., improving oxygenation of water layer at the water–sediment interface)(Padedda et. al. 2017).
There is an urgent need to take into consideration of climate change adaptation into the conservation and management of cold-water lakes globally.
Cover Photo: Great Meander River’s Delta in Anatolia (iStock by Gittyimage)
References:
- Carignan, R., & Kalff, J. (2002). Eutrophication in freshwater and coastal marine ecosystems. Environmental monitoring and assessment, 78(1-3), 5-37.
- Nazari-Sharabian, M., Ahmad, S., Karakouzian, M. (2018). Climate Change and Eutrophication: A Short Review. Engineering, Technology and Applied Science Research, 8(6), 3668-3672.
- Lu, X., Lu, Y., Chen, D., Su, C., Song, S., Wang, T., … & Khan, K. (2019). Climate change induced eutrophication of cold-water lake in an ecologically fragile nature reserve. Journal of Environmental Sciences, 75, 359-369.
- Padedda, B. M., Sechi, N., Lai, G. G., Mariani, M. A., Pulina, S., Sarria, M., … & Luglie, A. (2017). Consequences of eutrophication in the management of water resources in Mediterranean reservoirs: A case study of Lake Cedrino (Sardinia, Italy). Global Ecology and Conservation, 12, 21-35.
- Schindler, D. W., Elser, J. J., Gruner, D. S., Hobbie, J. E., & Sterner, R. W. (2008). Eutrophication of freshwater and marine ecosystems. Frontiers in Ecology and the Environment, 6(10), 439-447.
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