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Climate change could lead to larger algae blooms

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Griffith-led research has shown that both wind decreases and higher temperatures predicted by climate change could lead to larger algae blooms in the future.

Published in Water researchthe study found that a 20% decrease in wind speed will result in algal blooms of the freshwater cyanobacteria Microcystis nearly one and a half times larger than its current size.

“The impact this wind decrease will have on algal blooms is more than six times that of a 2°C increase in air temperature due to climate change,” said lead author Mohammad Hassan Ranjbar, a Ph.D. candidate at the Australian Rivers Institute.

“Harmful algal blooms of the freshwater cyanobacteria Microcystis is a global problem and is expected to increase with climate change, but the impact of atmospheric stills, the decrease in wind speed near the surface, has not been taken into account to date.”

“Our research is the first to show that atmospheric shutdown along with rising air temperatures can promote the blooming of these vibrant, colony-forming cyanobacteria.”

Co-author Professor David Hamilton, acting director of the Australian Rivers Institute, said this research shows that “wind speed should be included in all projections looking at changes in the frequency, distribution and magnitude of algal blooms under climate change.”

“The decrease in wind speed, which is expected to occur in several regions around the world with climate warming, reduces mixing in the water column in lakes and other bodies of water. The reduced turbulence in the water column allows floating cyanobacteria to surface and form blooms.”

To test whether wind stills affected the distribution and biomass of cyanobacteria in the water column, the researchers applied a new individual model that they combined with a hydrodynamic model to simulate the movement of water in the lake.

“For the first time, our model was able to drastically change the size of the algae colony in response to the turbulence, light, temperature and nutrients in the water column of a shallow urban lake,” said Mr. Mohammad Hassan.

“Using this model, it was quite clear that algal bloom formation was much more sensitive to the atmospheric slowing of wind speed associated with climate change than to warming temperatures.”

The authors emphasize that this atmospheric stillness should be included in predictions of algal blooms under climate change.

Harmful algal blooms become detectable along western Lake Erie

More information:
Mohammad Hassan Ranjbar et al, Effects of Atmospheric Standstill and Climate Warming on Cyanobacterial Bloom: An Individual-Based Modeling Approach, Water research (2022). DOI: 10.1016/j.watres.2022.118814

Provided by Griffith University

Quote: Climate change could lead to bigger algal blooms (2022, August 15) retrieved August 15, 2022 from https://phys.org/news/2022-08-climate-larger-algal-blooms.html

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