Navigation Links
Global warming harms lakes
Date:7/16/2012

This release is available in German.

Global warming also affects lakes. Based on the example of Lake Zurich, researchers from the University of Zurich demonstrate that there is insufficient water turnover in the lake during the winter and harmful Burgundy blood algae are increasingly thriving. The warmer temperatures are thus compromising the successful lake clean-ups of recent decades.

Many large lakes in Central Europe became heavily overfertilized in the twentieth century through sewage. As a result, algal blooms developed and cyanobacteria (photosynthetic bacteria) especially began to appear en masse. Some of these organisms form toxins that can compromise the use of the lake water. Dying algal blooms consume a lot of oxygen, thereby reducing the oxygen content in the lake with negative consequences for the fish stocks.

The problem with overfertilization was not merely the absolute amount of oxygen and phosphorus, the two most important nutrients for algae. Mankind has also changed the ratio between the two nutrients: The phosphorus load in lakes has been reduced vastly in recent decades, yet pollution with nitrogen compounds has not decreased on the same scale. The current ratio between the nutrients can thus trigger a mass appearance of certain cyanobacteria, even in lakes that have been deemed "restored".

Burgundy blood algae grow more rapidly

"The problem today is that mankind is changing two sensitive lake properties at the same time, namely the nutrient ratios and, with global warming, water temperature," explains Thomas Posch, a limnologist from the University of Zurich. In collaboration with Zurich Water Supply, he analyzed 40 years' worth of data in a study that has just been published in Nature Climate Change.

The evaluation of this historical data on Lake Zurich reveals that the cyanobacteria Planktothrix rubescens, more commonly known as Burgundy blood algae, has developed increasingly denser blooms in the last 40 years. Like many other cyanobacteria, Planktothrix contains toxins to protect itself from being eaten by small crabs. Burgundy blood algae were first described in Lake Zurich in 1899 and are a well-known phenomenon for Zurich Water Supply. Consequently, the lake water is painstakingly treated for the drinking-water supply to remove the organism and toxins completely from the raw water.

Warmer lakes have insufficient water turnover

But why does Planktothrix increasingly thrive? The most important natural control of the cyanobacteria blooms occurs in the spring, once the entire lake has cooled down vastly during the winter. Intensive winds trigger the turnover of the surface and deep water. If the turnover is complete, many cyanobacteria die off in the deep waters of Lake Zurich as they cannot withstand the high pressure, which is still 13 bars at depths of 130 meters. Another positive effect of this turnover is the transportation of fresh oxygen to the deep. However, the situation in Lake Zurich has also changed drastically in the last four decades. Global warming causes rising temperatures at the water surface. The current values are between 0.6 and 1.2 degrees Celsius above the 40-year average. The winters were increasingly too warm and the lake water was not able to turn over fully as the temperature difference between the surface and depths posed a physical barrier. The consequences are larger oxygen deficits for a longer period in the lake's deep water and an insufficient reduction of the Burgundy blood algae blooms.

Hope for cold, windy winters

"Unfortunately, we are currently experiencing a paradox. Even though we thought we had partly solved the nutrient problem, in some lakes global warming works against the clean-up measures. Therefore, we primarily need cold winters with strong winds again," says Posch. As far as the researchers are concerned, the winter of 2011/12 was just what the doctor ordered: The low temperatures and heavy storms allowed the lake to turn over completely and ultimately resulted in a reduction in Planktothrix.


'/>"/>

Contact: Thomas Posch
posch@limnol.uzh.ch
41-446-349-224
University of Zurich
Source:Eurekalert  

Related biology news :

1. Novo Nordisk and BGI establish global collaboration framework
2. EU-funded study underlines importance of Congo Basin for global climate and biodiversity
3. Global warming threat to coral reefs: Can some species adapt?
4. 1 solution to global overfishing found
5. Young researcher taking fight against global killer to the next level in Vietnam
6. Heightened Security Threats and Economic Issues Provide Fillip to Global Civil and Military Biometrics Market, Says Frost & Sullivan
7. Global Information Inc. Announces Discounted Conference Registration For Bio-IT World Asia and Biodetection Technologies 2012
8. Global effort launched to save turtles from extinction
9. New Biotech and Pharmaceutical Market Research from Global Information Inc Forecasts Strong Growth Coming Out of Recession
10. 2012 Forecast for US Molecular Diagnostics Market Now Available From Global Information Inc.
11. Desert to Rainforest global classroom links future teachers, classrooms in Phoenix and Panama
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Global warming harms lakes
(Date:2/13/2017)... Former 9/11 Commission border counsel and Special Counsel to ... of Identity Strategy Partners, LLP, today releases the following ... Protecting the Nation From Foreign Terrorist Entry Into the ... Trump,s ,Travel Ban, Executive Order gains more notoriety and ... ban, it is important that our national discourse regain ...
(Date:2/8/2017)... Feb. 8, 2017 About Voice Recognition Biometrics ... match it against a stored voiceprint template. Acoustic ... cadence, and tone are compared to distinguish between ... installation, as most PCs already have a microphone ... Voice recognition biometrics are most likely to be ...
(Date:2/8/2017)... , Feb. 7, 2017 The ... largely by the confluence of organizations, desires to ... for knowledge-based systems (password and challenge questions), biometrics ... and government systems. The market is driven by ... demarcation between consumer and enterprise uses cases, with ...
Breaking Biology News(10 mins):
(Date:2/15/2017)... , 15. Februar 2017  Trianni, Inc. („TRIANNI") ... Inc. (Janssen) eine Lizenzvereinbarung über die Verwendung der ... führenden Plattform für die Entdeckung monoklonaler Antikörper. ... neuartiges chimäres Gensegmentdesign aus, das Janssen den ... Antikörpern bietet und das für die schelle Isolierung ...
(Date:2/15/2017)... WASHINGTON, Feb. 15, 2017  Vanda Pharmaceuticals Inc. ... results for the fourth quarter and full year ... an exceptional year for Vanda as we continued ... and secured long-term exclusivity for Fanapt," said Mihael ... addition, our emerging pipeline with important 2017 milestones ...
(Date:2/15/2017)... -- Windtree Therapeutics, Inc. (Nasdaq: WINT ), ... therapies for respiratory diseases, will host a conference call ... EST on Thursday, February 16, 2017 to provide updates ... announced closing of a $10.5 million private offering and ... in the live call and take part in the ...
(Date:2/15/2017)... ... February 15, 2017 , ... ... a strategic partnership that puts Diameter Health technology in the hands of Lantana ... allows providers, exchanges, quality improvement and public health entities – all those mining ...
Breaking Biology Technology: