Cyanobacteria blooms can reduce water quality and impact human and animal health, with researchers now suggesting a study of lake bottoms could help to understand recent blooms.
Photo by Midge Eliassen
March 30 (UPI) -- To better understand the ecology of cyanobacteria and the origins of harmful blooms, the authors of a new study suggest scientists look below -- to cyanobacteria living on the bottom of freshwater lakes and ponds.
The new paper, published Tuesday in the Journal of Plankton Research, offers an overview of what scientists know about cyanobacteria, or blue-green algae, as well as the biggest unanswered questions.
The paper's authors suggest the mysteries of blue-green algae blooms, including how they will be affected by climate change, can be solved by a more comprehensive approach to cyanobacteria studies.
"Most studies of cyanobacteria focus on the times when they are visible in the water column," study author Kathryn Cottingham said in a press release.
"By concentrating on this part of the life cycle, we may be missing important clues about how these harmful organisms are responding to ongoing global change," said Cottingham, a professor of biology at Dartmouth College.
Blue-green algae blooms can sicken or kill animals. In humans, cyanobacteria's toxins can cause organ damage.
In some places, rising temperatures have fueled an increase in the scale and frequency of cyanobacteria blooms, which can alter the biochemistry of freshwater habitat and do lasting ecological damage.
Cyanobacteria proliferate in warmer, sunlit water. In the offseason, they sink to the bottom and overwinter in lakebed sediments.
When the water begins to warm again, overturning patterns in the water column help bring cyanobacteria back to the surface.
Climate change has altered overturning patterns in the water columns of lakes and ponds. In bodies of water, overturning has decreased, but in certain places, climate change has encouraged greater overturning.
For example, increases in heavy precipitation could cause water and sediment mixing and trigger blue-green algae blooms.
If warming water temperatures reduce the turnover of freshwater lakes and ponds, it's possible blue-green algae blooms will become less prolific over time.
"A more complete understanding of all stages of the cyanobacteria life cycle will enable plankton researchers to better predict how ongoing climate change will affect the frequency, intensity and duration of cyanobacteria blooms," authors wrote in their paper.
Scientists estimate that nutrient loading, temperature and precipitation are the primary factors that dictate cyanobacteria blooms.
But to better understand the interplay among these factors, the researchers say a better understanding of blue-green algae's overwintering process is needed.
"Our work indicates that cyanobacteria blooms could either increase or decrease as a result of climate change, necessitating preventative lake management to limit human health risks," said study co-author Cayelan Carey.
"Avoiding fertilizer use and installing waterfront buffers can help decrease cyanobacteria, thereby providing 'insurance' against potential cyanobacteria increases due to warmer temperatures in the future," said Carey, an associate professor of biological sciences at Virginia Tech.