| 1. |
- Bryhn, Andreas Christoffer, 1971-, et al.
(author)
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Predicting future effects from nutrient abatement and climate change on phosphorus concentrations in Lake Bourget, France
- 2010
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In: Ecological Modelling. - : Elsevier BV. - 0304-3800 .- 1872-7026. ; 221:10, s. 1440-1450
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Journal article (peer-reviewed)abstract
- Like many temperate European lakes, Lake Bourget (France) has suffered from eutrophication during the second half of the last century. Due to a remarkable policy restoration program, the lake has been recovering for the past 25 years after a massive decrease in total phosphorus (TP) loading. TP concentrations have decreased from about 100-120 to 20-25 µg/L. Additional efforts are, however, still required to obtain a perennially sustainable good ecological status and model parameterisation of fluxes can assist in predicting future outcomes, especially in the context of global warming. In this paper, a dynamic model (MeroLakeMab) was developed and tested with the purpose to reconstructthe loading history of Lake Bourget and to predict TP concentrations during scenarios of increased temperature, decreased water runoff and decreased P loading. Simulations suggested that the historical TP loading decrease may have been as extensive as 90%. Decreases in water discharge to Lake Bourget at magnitudes forecasted by the Intergovernmental Panel on Climate Change would not affect TP concentrations notably, but marked concentration changes could, however, occur if decreases in runoff would have a strong impact on the TP loading. Increasing temperature effects on yearly mean TP concentrations in the water column would be very small compared to effects from changes in the TP loading. Predictions such as these could be instrumental for future successful lake management.
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| 2. |
- Doubek, Jonathan P., et al.
(author)
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The extent and variability of storm-induced temperature changes in lakes measured with long-term and high-frequency data
- 2021
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In: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 66:5, s. 1979-1992
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Journal article (peer-reviewed)abstract
- The intensity and frequency of storms are projected to increase in many regions of the world because of climate change. Storms can alter environmental conditions in many ecosystems. In lakes and reservoirs, storms can reduce epilimnetic temperatures from wind-induced mixing with colder hypolimnetic waters, direct precipitation to the lake's surface, and watershed runoff. We analyzed 18 long-term and high-frequency lake datasets from 11 countries to assess the magnitude of wind- vs. rainstorm-induced changes in epilimnetic temperature. We found small day-to-day epilimnetic temperature decreases in response to strong wind and heavy rain during stratified conditions. Day-to-day epilimnetic temperature decreased, on average, by 0.28 degrees C during the strongest windstorms (storm mean daily wind speed among lakes: 6.7 +/- 2.7 m s(-1), 1 SD) and by 0.15 degrees C after the heaviest rainstorms (storm mean daily rainfall: 21.3 +/- 9.0 mm). The largest decreases in epilimnetic temperature were observed >= 2 d after sustained strong wind or heavy rain (top 5(th) percentile of wind and rain events for each lake) in shallow and medium-depth lakes. The smallest decreases occurred in deep lakes. Epilimnetic temperature change from windstorms, but not rainstorms, was negatively correlated with maximum lake depth. However, even the largest storm-induced mean epilimnetic temperature decreases were typically <2 degrees C. Day-to-day temperature change, in the absence of storms, often exceeded storm-induced temperature changes. Because storm-induced temperature changes to lake surface waters were minimal, changes in other limnological variables (e.g., nutrient concentrations or light) from storms may have larger impacts on biological communities than temperature changes.
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| 3. |
- Jenny, Jean Philippe, et al.
(author)
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Scientists’ Warning to Humanity: Rapid degradation of the world's large lakes
- 2020
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In: Journal of Great Lakes Research. - : Elsevier BV. - 0380-1330. ; 46:4, s. 686-702
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Research review (peer-reviewed)abstract
- © 2020 The Authors Large lakes of the world are habitats for diverse species, including endemic taxa, and are valuable resources that provide humanity with many ecosystem services. They are also sentinels of global and local change, and recent studies in limnology and paleolimnology have demonstrated disturbing evidence of their collective degradation in terms of depletion of resources (water and food), rapid warming and loss of ice, destruction of habitats and ecosystems, loss of species, and accelerating pollution. Large lakes are particularly exposed to anthropogenic and climatic stressors. The Second Warning to Humanity provides a framework to assess the dangers now threatening the world's large lake ecosystems and to evaluate pathways of sustainable development that are more respectful of their ongoing provision of services. Here we review current and emerging threats to the large lakes of the world, including iconic examples of lake management failures and successes, from which we identify priorities and approaches for future conservation efforts. The review underscores the extent of lake resource degradation, which is a result of cumulative perturbation through time by long-term human impacts combined with other emerging stressors. Decades of degradation of large lakes have resulted in major challenges for restoration and management and a legacy of ecological and economic costs for future generations. Large lakes will require more intense conservation efforts in a warmer, increasingly populated world to achieve sustainable, high-quality waters. This Warning to Humanity is also an opportunity to highlight the value of a long-term lake observatory network to monitor and report on environmental changes in large lake ecosystems.
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| 4. |
- Weyhenmeyer, Gesa A., Professor, et al.
(author)
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Global Lake Health in the Anthropocene : Societal Implications and Treatment Strategies
- 2024
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In: Earth's Future. - : American Geophysical Union (AGU). - 2328-4277. ; 12:4
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Research review (peer-reviewed)abstract
- The world's 1.4 million lakes (>= 10 ha) provide many ecosystem services that are essential for human well-being; however, only if their health status is good. Here, we reviewed common lake health issues and classified them using a simple human health-based approach to outline that lakes are living systems that are in need of oxygen, clean water and a balanced energy and nutrient supply. The main reason for adopting some of the human health terminology for the lake health classification is to increase the awareness and understanding of global lake health issues. We show that lakes are exposed to various anthropogenic stressors which can result in many lake health issues, ranging from thermal, circulatory, respiratory, nutritional and metabolic issues to infections and poisoning. Of particular concern for human well-being is the widespread lake drying, which is a severe circulatory issue with many cascading effects on lake health. We estimated that similar to 115,000 lakes evaporate twice as much water as they gain from direct precipitation, making them vulnerable to potential drying if inflowing waters follow the drying trend, putting more than 153 million people at risk who live in close vicinity to those lakes. Where lake health issues remain untreated, essential ecosystem services will decline or even vanish, posing a threat to the well-being of millions of people. We recommend coordinated multisectoral and multidisciplinary prevention and treatment strategies, which need to include a follow-up of the progress and an assessment of the resilience of lakes to intensifying threats. Priority should be given to implementing sewage water treatment, mitigating climate change, counteracting introductions of non-native species to lakes and decreasing uncontrolled anthropogenic releases of chemicals into the hydro-, bio-, and atmosphere. Lakes around the world come in an array of sizes, shapes and colors, each telling a unique story of geological history and environmental importance. When lakes are healthy they contribute to the achievement of the global sustainable development goals by providing many important ecosystem services. Lakes are, however, not always healthy. Here, it is shown that lakes can suffer from a large variety of health issues, ranging from thermal, circulatory, respiratory, nutritional and metabolic issues to infections and poisoning. Without improved treatment strategies, many of the health issues may become chronic, affecting millions of people who are dependent on the ecosystem services from the lakes. To prevent and cure lakes from critical health conditions, strategies that are similar to those used in human healthcare should be applied: intervention and preventative actions before health problems occur, regular screening and early identification of lake health issues, and remediation and mitigation efforts at an appropriate scale, spanning from local to global. Anthropogenic stressors can cause lake health issues that range from thermal, circulatory, respiratory, nutritional and metabolic issues to infections and poisoning Lake health varies geographically, with the highest risk of critical conditions occurring in densely populated low-income countries There is an urgent need to follow-up the progress of treatments and to make adjustments whenever needed
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| 5. |
- Weyhenmeyer, Gesa A., et al.
(author)
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Widespread diminishing anthropogenic effects on calcium in freshwaters
- 2019
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In: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9
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Journal article (peer-reviewed)abstract
- Calcium (Ca) is an essential element for almost all living organisms. Here, we examined global variation and controls of freshwater Ca concentrations, using 440 599 water samples from 43 184 inland water sites in 57 countries. We found that the global median Ca concentration was 4.0 mg L-1 with 20.7% of the water samples showing Ca concentrations <= 1.5 mg L-1, a threshold considered critical for the survival of many Ca-demanding organisms. Spatially, freshwater Ca concentrations were strongly and proportionally linked to carbonate alkalinity, with the highest Ca and carbonate alkalinity in waters with a pH around 8.0 and decreasing in concentrations towards lower pH. However, on a temporal scale, by analyzing decadal trends in > 200 water bodies since the 1980s, we observed a frequent decoupling between carbonate alkalinity and Ca concentrations, which we attributed mainly to the influence of anthropogenic acid deposition. As acid deposition has been ameliorated, in many freshwaters carbonate alkalinity concentrations have increased or remained constant, while Ca concentrations have rapidly declined towards or even below pre-industrial conditions as a consequence of recovery from anthropogenic acidification. Thus, a paradoxical outcome of the successful remediation of acid deposition is a globally widespread freshwater Ca concentration decline towards critically low levels for many aquatic organisms.
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