Hundreds of lakes in U.S., Europe are losing oxygen

https://apnews.com/article/ny-state-wire-europe-lakes-climate-change-science-043d6895aad97e01b0d30489df3c426a?utm_source=InsideClimate+News&utm_campaign=adfa20848a-&utm_medium=email&utm_term=0_29c928ffb5-adfa20848a-328507972

 

By DREW COSTLEY

June 2, 2021

 

Oxygen levels have dropped in hundreds of lakes in the United States and Europe over the last four decades, a new study found.

And the authors said declining oxygen could lead to increased fish kills, algal blooms and methane emissions.

Researchers examined the temperature and dissolved oxygen — the amount of oxygen in the water — in nearly 400 lakes and found that declines were widespread. Their study, published Wednesday in the journal Nature, found dissolved oxygen fell 5.5 % in surface waters of these lakes and 18.6% in deep waters.

The authors said their findings suggest that warming temperatures and decreased water clarity from human activity are causing the oxygen decline.

“Oxygen is one of the best indicators of ecosystem health, and changes in this study reflect a pronounced human footprint,” said co-author Craig E. Williamson, a biology professor at Miami University in Ohio.

That footprint includes warming caused by climate change and decreased water clarity caused in part by runoff from sewage, fertilizer, cars and power plants.

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About a quarter of the lakes examined actually showed increasing oxygen in surface waters, which Rose says is a bad sign because it’s likely attributable to increased algal blooms — sudden growth of blue green algae.

In these lakes, he said, dissolved oxygen was “very low” in deep waters and was unlivable for many species.

And the sediment in such oxygen-starved lakes tends to give off methane, a potent greenhouse gas, research shows.


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