For most life forms on Earth, oxygen is a necessity, not an optional extra – and because of our warming planet, oxygen is quickly disappearing from our freshwater lakes, putting aquatic life and ecosystems under threat.
Changes threaten biodiversity and drinking water quality
Lake Stechlin is an example of how oxygen is increasingly depleting in lakes. | Photo: Solvin Zankl
Oxygen levels in freshwater lakes are declining rapidly – faster than in the oceans. Over the past forty years, for example, oxygen levels in the deep waters of temperate lakes have dropped by nearly 19 percent. This is shown by a study with IGB published today in the journal Nature. This trend is mainly due to climate change and threatens freshwater biodiversity and drinking water quality.
The international research team, led by the U.S. Rensselaer Polytechnic Institute, analyzed a total of more than 45,000 oxygen and temperature profiles collected from nearly 400 lakes around the globe since 1941. Most of the long-term data came from the temperate zone, which ranges from 23 to 66 degrees north and south latitude. The analyses show that since 1980, oxygen levels in the lakes studied have declined by 5.5 percent at the surfa
And when you start losing oxygen, you have the potential to lose species. Lakes are losing oxygen 2.75-9.3 times faster than the oceans, a decline that will have impacts throughout the ecosystem.
While lakes only cover about 3 percent of the surface of the Earth, they contain a disproportionate concentration of the planet s biodiversity . Lakes are indicators or sentinels of environmental change and potential threats to the environment because they respond to signals from the surrounding landscape and atmosphere, said lead author Stephen Jane, also of Rensselaer. We found that these disproportionally more biodiverse systems are changing rapidly, indicating the extent to which ongoing atmospheric changes have already impacted ecosystems.
About a quarter of the lakes examined showed increasing oxygen in surface waters, which researchers says is a bad sign because it's likely attributable to increased algal blooms