World’s Lakes Losing Oxygen Rapidly as Planet Warms

News Release Release Date: June 2, 2021 9:05 a.m.

Research published today in Nature found that oxygen levels in lakes across the northern hemisphere are declining 2.8 to 9.3 times faster than in the world’s oceans – a trend which threatens freshwater fisheries, biodiversity, and drinking water quality.

Researchers analyzed over 45,000 dissolved oxygen and temperature profiles collected since 1941 from nearly 400 lakes around the globe.

University of Regina research in the study showed that rates of oxygen loss are particularly high in Canadian Prairie lakes of Saskatchewan where rapid warming, nutrient pollution, and blooms of toxic cyanobacteria combine to deplete oxygen from the bottom of lakes. 

“All complex life depends on oxygen. It’s the support system for aquatic food webs. And when you start losing oxygen, you have the potential to lose species,” said Kevin Rose, corresponding author and professor at Rensselaer Polytechnic Institute in New York.  “Loss of up to 18 per cent of deepwater oxygen since 1980 has a profound effect on the biology and chemistry of lakes”.

Peter Leavitt, a Canada Research Chair at University of Regina and lead investigator of the 28-year Qu’Appelle Long-Term Ecological Research program says that Prairie lakes may be especially vulnerable. 

“Warming of surface waters reduces lake mixing and the flow of atmospheric oxygen into the deep waters where fish often hide to avoid surface heat.  Loss of this deep oxygen suffocates native fishes, but can benefit some invasive species which in turn harm the lake’s food web,” says Leavitt.

In addition to warming, Prairie lakes have high levels of nutrients which increase the risk of algae and cyanobacteria blooms. Oxygen levels decline further when these blooms die, sink to the lake bottom, and decompose.

Although lakes make up only about three per cent of Earth’s land surface, they contain a disproportionate concentration of the planet’s biodiversity.  Lead author Stephen F. Jane, who completed his PhD with Rose, said the changes are concerning both for their potential impact on freshwater ecosystems and for what they suggest about environmental change in general.

“Lakes are indicators or ‘sentinels’ of threats to the environment because they respond to signals from the surrounding landscape and atmosphere.  We found that these biodiverse lakes are changing rapidly, showing that atmospheric warming has already impacted freshwater ecosystems,” Jane said.

In addition to biodiversity loss, declines in dissolved oxygen can increase greenhouse gas emissions from lakes, intensify pollution of surface waters with toxic metals, and favour blooms of toxic algae – all factors that affect human health.

“Climate warming and nutrient enrichment of prairie lakes have together caused an increase in the frequency and intensity of toxic algal blooms during the past 30 years,” says Leavitt.  “Given that we expect both factors will intensify during the next 50 years, it seems likely that blooms will increase further and that oxygen will continue to be choked out of the water.”

“Widespread deoxygenation of temperate lakes” is an international collaboration led by Rose and Jane, with dozens of collaborators from the Global Lake Ecological Observatory Network (GLEON).  The research was based in universities, environmental consulting firms, and government agencies around the world. 

A copy of the Paper and its Supplementary information is available at https://www.nature.com/articles/s41586-021-03550-y

Ciscosmall Cyanobacteria1small
Dead fish on shore of Katepwa Lake, Saskatchewan.  This photo is of a Cisco (aka Coregonus artedi).  Normally, this species lives in cool deep water, but can be pushed into lethally warm surface waters by the loss of oxygen at the lake bottom.  Cisco, and related whitefish, can exhibit mass die-offs in Saskatchewan during summer due to overlapping conditions of high water temperature and low oxygen.  Global warming is making this sort of die off much more likely to occur by both warming surface waters and removing oxygen from the bottom of lakes. Photo by McKenzie Van Eaton.  Click here for high resolution photogragh. Summer bloom of potentially-toxic cyanobacteria on Katepwa Lake, Saskatchewan.  Species pictured here are promoted by warm, nutrient-rich waters.  When they die and sink to the bottom of the lake, their degradation reduces the oxygen content of deepwaters.  Photo by McKenzie Van Eaton. Click here for high resolution photograph.

 

Cyanobacteriasmall.jpg
Summer bloom of potentially-toxic cyanobacteria on Katepwa Lake, Saskatchewan.  Species pictured here are promoted by warm, nutrient-rich waters.  When they die and sink to the bottom of the lake, their degradation reduces the oxygen content of deepwaters.  Photo by McKenzie Van Eaton. Click here for high resolution photograph.

 

About the University of Regina:

The University of Regina—with campuses located on Treaty 4 and Treaty 6 territories, the ancestral lands of the Cree, Saulteaux, Dakota, Lakota and Nakoda nations and the homeland of the Métis—is a comprehensive, mid-sized university that traces its roots back to the creation of Regina College in 1911. Today, more than 16,600 students study within the University's 10 faculties and three federated colleges (Campion College, First Nations University of Canada, and Luther College). The University of Regina has an established reputation for excellence and innovative programs that lead to undergraduate, master, and doctoral degrees.

BACKGROUNDER

  • The University of Regina’s Institute of Environmental Change and Society (IECS) is a world-class research facility build on nearly three decades of research by environmental scientists at University of Regina. The Institute is unique to the Canadian Prairies, and is a member of an elite series of environmental institutes in Canada. IECS provides world-class infrastructure and research expertise in environmental sciences for faculty, students and staff enabling individuals and multidisciplinary groups to conduct cutting-edge scientific research to advance the provincial, national and international research agendas.
  • Members of the IECS have studied Prairie lakes since 1994 as part of the Qu’Appelle Valley Long-Term Ecological Research program.
  • Now in its 28th season, the Qu’Appelle project is one of Canada’s longest running freshwater research programs. These long-term research programs are essential for understanding the decades-long effects of climate change and human activities such as urbanization, land use change and atmospheric pollution. 
Media contact: Peter R. Leavitt FRSC
Canada Research Chair in Environmental Change and Society
Director of Institute of Environmental Change and Society
University of Regina
Cell:  (306) 591-2659
Email:  Peter.Leavitt@uregina.ca
Skype: PeterRLeavitt (in Saskatchewan, Canada)
Twitter: @UofRLimno
Website: http://www.iecs-uregina.ca/

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About Rensselaer Polytechnic Institute

Founded in 1824, Rensselaer Polytechnic Institute is America’s first technological research university. Rensselaer encompasses five schools, 32 research centers, more than 145 academic programs, and a dynamic community made up of more than 7,900 students and over 100,000 living alumni. Rensselaer faculty and alumni include more than 145 National Academy members, six members of the National Inventors Hall of Fame, six National Medal of Technology winners, five National Medal of Science winners, and a Nobel Prize winner in Physics. With nearly 200 years of experience advancing scientific and technological knowledge, Rensselaer remains focused on addressing global challenges with a spirit of ingenuity and collaboration. To learn more, please visit www.rpi.edu.

 

Media Contact: Dr. Kevin Rose
Kolleck Career Development Chair in Freshwater Ecology
Department of Biological Sciences
Rensselaer Polytechnic Institute
Troy, NY 12180
Tel: 518-276-8288
Cell: 973-919-4278
Email: rosek4@rpi.edu, kev.c.rose@gmail.com
skype: kevin.c.rose
Twitter: @kevcrose
Website: http://aquatics-lab.weebly.com/

 

Stephen Jane
Department of Biological Sciences
Rensselaer Polytechnic Institute
Troy, NY 12180
cell: 518-416-2879

 

RPI Contact: Reeve Hamilton
Director of Media Relations
518-833-4277
hamilr5@rpi.edu

Visit the Rensselaer research and discovery blog: http://everydaymatters.rpi.edu/

Follow us on Twitter: @RPINews

 

 

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