Quantcast
Environmental News for a Healthier Planet and Life

Help Support EcoWatch

Toxic Algal Blooms Connected to Climate Change and Industrial Agriculture

Climate
Toxic Algal Blooms Connected to Climate Change and Industrial Agriculture

Nutrient enrichment and climate change are posing yet another concern of growing importance—an apparent increase in the toxicity of some algal blooms in freshwater lakes and estuaries around the world, which threatens aquatic organisms, ecosystem health and human drinking water safety.

As this nutrient enrichment, or “eutrophication” increases, so will the proportion of toxin-producing strains of cyanobacteria in harmful algal blooms, scientists said.

Toxic microcystin bacteria float, along with this dead fish, on the surface of freshwater lakes. Photo credit: Oregon State University

Researchers from Oregon State University and the University of North Carolina at Chapel Hill will outline recent findings in an analysis Friday in the journal Science.

Cyanobacteria are some of the oldest microorganisms on Earth, dating back about 3.5 billion years to a time when the planet was void of oxygen and barren of most life. These bacteria are believed to have produced the oxygen that paved the way for terrestrial life to evolve. They are highly adaptive and persistent, researchers say, and today are once again adapting to new conditions in a way that threatens some of the life they originally made possible.

A particular concern is Microcystis sp., a near-ubiquitous cyanobacterium that thrives in warm, nutrient-rich and stagnant waters around the world. Like many cyanobacteria, it can regulate its position in the water column, and often forms green, paint-like scums near the surface.

In a high-light, oxidizing environment, microcystin-producing cyanobacteria have a survival advantage over other forms of cyanobacteria that are not toxic. Over time, they can displace the nontoxic strains, resulting in blooms that are increasingly toxic.

“Cyanobacteria are basically the cockroaches of the aquatic world,” said Timothy Otten, a postdoctoral scholar in the OSU College of Science and College of Agricultural Sciences, whose work has been supported by the National Science Foundation. “They're the uninvited guest that just won't leave.”

A thick mat of toxic microcystins cyanobacteria on Lake Taihu in China gets stirred up in the wake of a boat. Photo credit: Hans Paerl/ University of North Carolina

“When one considers their evolutionary history and the fact that they've persisted even through ice ages and asteroid strikes, it's not surprising they're extremely difficult to remove once they’ve taken hold in a lake,” Otten said. “For the most part, the best we can do is to try to minimize the conditions that favor their proliferation.”

Researchers lack an extensive historical record of bloom events and their associated toxicities to put current observations into a long-term context.  However, Otten said, “If you go looking for toxin-producing cyanobacteria, chances are you won't have to look very long until you find some.”

There are more than 123,000 lakes greater than 10 acres in size spread across the U.S., and based on the last U.S. Environmental Protection Agency's National Lakes Assessment, at least one-third may contain toxin-producing cyanobacteria. Dams, rising temperatures and carbon dioxide concentrations, droughts, and increased runoff of nutrients from urban and agricultural lands are all compounding the problem.

Many large, eutrophic lakes such as Lake Erie are plagued each year by algal blooms so massive that they are visible from outer space. Dogs have died from drinking contaminated water.

Researchers studying cyanobacterial toxins say it’s improbable that their true function was to be toxic, since they actually predate any predators. New research suggests that the potent liver toxin and possible carcinogen, microcystin, has a protective role in cyanobacteria and helps them respond to oxidative stress. This is probably one of the reasons the genes involved in its biosynthesis are so widespread across cyanobacteria and have been retained over millions of years.

Because of their buoyancy and the location of toxins primarily within the cell, exposure risks are greatest near the water's surface, which raises concerns for swimming, boating and other recreational uses.

Researchers take samples from Lake Taihu in China, when it was heavily contaminated with toxic algal blooms that turned the surface water green. Photo credit: Oregon State University

Also, since cyanobacteria blooms become entrenched and usually occur every summer in impacted systems, chronic exposure to drinking water containing these compounds is an important concern that needs more attention, Otten said.

“Water quality managers have a toolbox of options to mitigate cyanobacteria toxicity issues, assuming they are aware of the problem and compelled to act,” Otten said. “But there are no formal regulations in place on how to respond to bloom events.

“We need to increase public awareness of these issues,” Otten concluded. “With a warming climate, rising carbon dioxide levels, dams on many rivers and overloading of nutrients into our waterways, the magnitude and duration of toxic cyanobacterial blooms is only going to get worse.”

The Trump administration has weakened fuel-efficiency requirements for the nation's cars and trucks. Drew Angerer / Getty Images

As the days tick down to next month's presidential election, debate rages over the U.S. government's handling of the COVID-19 pandemic with critics of President Donald Trump calling for his ouster due to his failure to protect the American public.

Read More Show Less

EcoWatch Daily Newsletter

Researchers have discovered a link between air pollution, food delivery and plastic waste. Sorapop / iStock / Getty Images Plus

Researchers from the National University of Singapore (NUS) have discovered a link between air pollution, food delivery and plastic waste.

Read More Show Less

Trending

Plain Naturals offers a wide variety of CBD products including oils, creams and gummies.

Plain Naturals is making waves in the CBD space with a new product line for retail customers looking for high potency CBD products at industry-low prices.

Read More Show Less
One report in spring 2020 found that 38% of students at four-year universities were food-insecure. Frederic J. Brown / AFP / Getty Images

By Matthew J. Landry and Heather Eicher-Miller

When university presidents were surveyed in spring of 2020 about what they felt were the most pressing concerns of COVID-19, college students going hungry didn't rank very high.

Read More Show Less
Coast Guard members work to clean an oil spill impacting Delaware beaches. U.S. Coast Guard District 5

Environmental officials and members of the U.S. Coast Guard are racing to clean up a mysterious oil spill that has spread to 11 miles of Delaware coastline.

Read More Show Less

Support Ecowatch