CLIMATE: Study: Warming lakes smother fish, foul drinking waterNew research warns that climate change-driven drops in oxygen levels in the world...CLIMATE: Study: Warming lakes smother fish, foul drinking water
New research warns that climate change-driven drops in oxygen levels in the world's freshwater lakes threaten drinking water and biodiversity and can possibly cause the release of more methane, a super potent greenhouse gas.
A survey of hundreds of freshwater temperate lakes across the globe found that as temperatures rise, oxygen levels have fallen 5.5% at the surface and almost 19% in deep waters during the past four decades — up to nine times faster than decreases observed in the world's oceans, according to a study published today in Nature.
The findings are worrisome because cratering oxygen levels pose a threat to cold-water and oxygen-sensitive species like trout, can spur the spread of toxic algal blooms that can affect drinking water quality, and possibly cause more storage and outgassing of methane, said the study's authors from the Rensselaer Polytechnic Institute in New York.
"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," Stephen Jane, the lead author and a former researcher at Rensselaer, said in a press release.
"We found that these disproportionally more biodiverse systems are changing rapidly, indicating the extent to which ongoing atmospheric changes have already impacted ecosystems," said Jane, who is now a fellow at Cornell University.
The findings also have implications for greenhouse gas emissions.
Authors noted that falling oxygen levels can create an environment where bacteria thrive, including those that produce methane.
According to the study, lakes may potentially be releasing larger amounts of methane to the atmosphere as a result of that oxygen loss. What's more, sediments release more phosphorus under low oxygen conditions, adding nutrients to already stressed waters, according to the report.