Algal blooms and toxic cyanobacteria becoming more common with global warming

Algae blooms are becoming increasingly common in bodies of water around the globe, as warmer temperatures and increased nutrient runoff (largely from agriculture) fuel their growth. And they’re expected to get worse with climate change, as more frequent heavy storms wash fertilizer into bodies of water and overwhelm pipes that carry both storm water and sewage.

A recent report conducted by scientists from Oregon State University and the University of North Carolina found that blooms of toxic cyanobacteria pose an increasingly pressing threat to the United States’ drinking water. Not all cyanobacteria produce toxins — but those that do, especially when found in high concentration, can cause skin irritation, gastrointestinal illness, and liver damage, as well as fatalities in pets, wildlife, and, in rare cases, humans.

“The biggest health concern with cyanobacteria in sources of drinking water is that there’s very little regulatory oversight, and it remains unclear what level of monitoring is being voluntarily conducted by drinking water utilities,” Tim Otten, a postdoctoral scholar in Oregon State University’s Department of Microbiology, said in a press release.

The UNC and OSU report concludes that blooms of toxic cyanobacteria, or blue-green algae, are a poorly monitored and underappreciated risk to recreational and drinking water quality in the United States, and may increasingly pose a global health threat.  Several factors are contributing to the concern. Temperatures and carbon dioxide levels have risen, many rivers have been dammed worldwide, and wastewater nutrients or agricultural fertilizers in various situations can cause problems in rivers, lakes and reservoirs.

One cannot tell visually if an algal bloom will be toxic or not,  Otten said, and traditional microscopic cell counting and other approaches to assess risk are too slow for making time-sensitive, public health decisions. New DNA-based techniques can be used by experts to estimate health risks faster and cheaper than traditional methods.

Cyanobacterial toxins are not destroyed by boiling. However, individuals concerned about the safety of their drinking water may use regularly-changed point-of-use carbon filtration devices that are effective in reducing these health risks.

People should also develop an awareness of what cyanobacteria look like, in a natural setting appearing as green, paint-like surface scums. They should avoid water recreation on a lake or river that has these characteristics, researchers said.