A new study warns that freshwater lakes are losing oxygen rapidly due to global warming, even faster than the world's oceans, and researchers at Rensselaer Polytechnic Institute in New York surveyed the oxygen levels in freshwater lakes in the temperate zone, which extends from 23 to 66 degrees north and south, including Bleelham Tarn in the United Kingdom and Lake Mendota in the United States.
They found that oxygen levels in lakes in this region have decreased by 5.5% at the surface and 18.6% in deep water since 1980. Freshwater lakes are bodies of still, unsalted water surrounded by land, and they are vital to water sources for humans and microorganisms, therefore, low freshwater oxygen threatens biodiversity and the quality of human drinking water.
Although lakes make up only about 3% of the Earth's surface, they also contain a significant concentration of the planet's biodiversity.
Study researcher Kevin Rose, a professor at Rensselaer Polytechnic Institute said, the implications of low oxygen in freshwater are enormous.
All complex life forms depend on oxygen, it's the support system for aquatic food webs, and when you start losing oxygen, you're likely to lose some species. Lakes are losing oxygen 2.75 to 9.3 times faster than oceans, a reduction that will have effects throughout the ecosystem. When oxygen levels drop, bacteria that thrive in oxygen-free environments, such as those that produce potent greenhouse gases, begin to multiply.
This likely means that the lakes are releasing increased amounts of methane into the atmosphere as a result of the loss of oxygen, a devastating double whammy for the environment.