PNAS
Canoeing the jacques Cartier_Photo by Jake Dyson |
PNAS
Canoeing the jacques Cartier_Photo by Jake Dyson |
Widespread, long-term declines in temperate lake oxygen levels have been reported in Nature this week. This trend, calculated for nearly 400 lakes within an 80-year period, may be linked to warming temperatures and decreasing water clarity. The declines could threaten essential lake ecosystems.
The concentration of dissolved oxygen in aquatic systems can affect the balance of nutrients, biodiversity, the quality of drinking water and greenhouse gas emissions. While oxygen loss in oceans has been documented, the changes in dissolved oxygen concentrations in lakes are less well understood, in part owing to a lack of long-term and large-scale studies.Kevin Rose and authors measured temperature and dissolved oxygen levels for almost 400 lakes (mostly in Europe and the United States) between 1941 and 2017. Declines in dissolved oxygen are up to nine times greater than those observed in the oceans.
Increased water temperatures are associated with reduced oxygen concentration in surface waters. And lower oxygen levels in deeper waters are linked to the formation of distinct thermal layers at different depths, along with reduced water clarity.
There were some exceptions to these trends; for example, a large subset of 87 lakes exhibited increases in both water temperature and dissolved oxygen concentration. However, this anomaly could be attributed to algal blooms, which may increase concentrations at the surface, but reduce oxygen solubility lower down.
Human activity and warming temperatures are expected to continue to drive future losses in lake dissolved oxygen.
As the authors conclude, ongoing, rigorous efforts will be needed to counter these effects.
The Narwhal
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The Seal River. A Gov't. of Manitoba photo. |
The Seal River is Manitoba’s only major waterway that hasn’t been dammed — and five Indigenous communities have banded together to keep it that way. Story here.
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The freshwater turtle, Emydura macquarii. Credit: Claudia Santori. |
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Baby Emydura macquarii. Credit: Tom Burd. |
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Lk. Winnipeg, Manitoba, Canada, with Reindeer Is. in the lower right. Photo credit - European Space Agency.
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Echo Lake, SK. Photo by Joe Mabel from Seattle. |
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Microplastics in sediments from the rivers Elbe (A), Mosel (B), Neckar (C), and Rhine (D).Note the diverse shapes (filaments, fragments, and spheres) and that not all items are microplastics (e.g., aluminum foil (C) and glass spheres and sand (D), white arrowheads). The white bars represent 1 mm. PhotoS by Martin Wagner et al.
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A lake in northwestern Ontario. Photo by PinP. |
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Dr. Eva Pip taught biology at the U of W for more than 50 years before retiring in 2016. She has published almost 100 peer-reviewed articles in her career. More than 800 scientists in serious academic circles around the world have cited her work, as a building block for their own. |
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The late David Schindler was a Rhodes scholar and internationally celebrated scientist, with a Ph.D in ecology. He co-authored the book, “The Algal Bowl: Overfertilization of the World’s Freshwaters and Estuaries.” |
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A dog swims in a poison
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They've been known to sicken people and kill animals. Many
communities as well as cottagers draw their drinking water from the lake.” Coliform
bacteria (such as E coli) were also associated with phosphorus levels. |
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Meanwhile, Lake Winnipeg (above), the world's 10th largest freshwater lake, gets increasingly polluted with algal blooms that can be seen from space. |
Eco Watch The pollution is even worse than earlier feared. Story here. RELATED: Research Suggests Our Past, Prolific Use Of The Insecticid...