Eutrophication, the cycle whereby nutrients overstimulate the growth of potentially harmful plankton and cyanobacterial 鈥榖looms鈥 in freshwater lakes, has become a problem for over 60% of global inland waters. The problem is set to be exacerbated by climate change, and so our priority should be to further reduce external nutrient inputs to diminish the basis of cyanobacterial bloom outbreaks.
The study of one lake in China, an important source of water for over 20 million people and for industry, establishes the mechanisms between lake heatwaves and potentially poisonous cyanobacteria 鈥榖looms鈥.
The research by Dr Iestyn Woolway of 新香港六合彩开奖结果 and research colleagues in the Chinese Academy of Sciences, Nanjing, China and Aarhus University, Denmark, published in Science of the Total Environment () studies the heatwave experienced in 2022 in Lake Taihu, one of China鈥檚 largest freshwater lakes situated in the Yangtze delta, and the associated cyanobacteria blooms. (Cyanobacterial are similar to plankton. Under certain conditions they can thrive in freshwater causing harm to other plants and animals).
Increasing surface air temperature is one of the most recognised consequences of man-made climate change.聽 In lakes, these conditions are exacerbated by 鈥榬un-offs鈥 from other human activities which add nutrients to the lakes, these in turn, help the cyanobacteria to thrive. An increase in lake surface water temperature has a knock-on effect on the entire lake environment.
Woolway urges,
鈥淚n addition to reducing run-off into freshwater as a result of our activities, we should be working towards systematic monitoring, prediction and early warning to reduce the damaging impact of heatwaves on lake ecosystems. We need to better understand the mechanisms and triggers in lakes with different nutrient levels in order to formulate strategies to address and adapt to climate change.鈥
Explaining the background Woolway adds,
鈥淭he whole thing becomes a vicious circle when heatwaves occur. An increased temperature reduces vertical mixing within the freshwater water column. This benefits buoyant cyanobacteria floating and forming dense surface blooms. These dense blooms, in turn, slightly increase the water temperature. The lower winds experienced during heatwaves also contribute to reduced mixing in the water column聽 and reduce dissolved oxygen in the water. In turn, the low dissolved oxygen levels at the lake bottom increase the release of phosphorus from the sediment, which then supports further growth of more cyanobacteria.鈥
鈥淗eatwaves are predicted to increase eleven-fold during this century, and this will have profound negative effects on the structure, function, and ecosystem services of aquatic systems.鈥
Lake Taihu Cyanobacteria bloom.
![Green cyanobacteria bloom in water](/sites/default/files/styles/3x2_900w/public/2023-07/Lake%20Taihu%20blooms-1.jpg?h=7357b006&itok=CJkkdS2Q)
![a small craft on the lake- the water behind the boat seems to have a green film.](/sites/default/files/styles/3x2_900w/public/2023-07/Lake%20Taihu%20blooms-2.jpg?h=9f5c04b0&itok=G79hW71Y)
![Visible green growth.](/sites/default/files/styles/3x2_900w/public/2023-07/Lake%20Taihu%20blooms-3.jpg?h=31a7c8e7&itok=zvvhlmLV)