Quantcast
Environmental News for a Healthier Planet and Life

Help Support EcoWatch

Toxic Algal Blooms Connected to Climate Change and Industrial Agriculture

Climate

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researchers say, and today are once again adapting to new conditions in a way that threatens some of the life they originally made possible.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.”

EcoWatch Daily Newsletter

The Anderson Community Group. Left to right, Caroline Laur, Anita Foust, the Rev. Bryon Shoffner, and Bill Compton, came together to fight for environmental justice in their community. Anderson Community Group

By Isabella Garcia

On Thanksgiving Day 2019, right after Caroline Laur had finished giving thanks for her home, a neighbor at church told her that a company had submitted permit requests to build an asphalt plant in their community. The plans indicated the plant would be 250 feet from Laur's backdoor.

Read More Show Less
Berber woman cooks traditional flatbread using an earthen oven in her mud-walled village home located near the historic village of Ait Benhaddou in Morocco, Africa on Jan. 4, 2016. Creative Touch Imaging Ltd. /NurPhoto / Getty Images

By Danielle Nierenberg and Jason Flatt

The world's Indigenous Peoples face severe and disproportionate rates of food insecurity. While Indigenous Peoples comprise 5 percent of the world's population, they account for 15 percent of the world's poor, according to the World Health Organization.

Read More Show Less
Danny Choo / CC BY-SA 2.0

By Olivia Sullivan

One of the many unfortunate outcomes of the coronavirus pandemic has been the quick and obvious increase in single-use plastic products. After COVID-19 arrived in the United States, many grocery stores prohibited customers from using reusable bags, coffee shops banned reusable mugs, and takeout food with plastic forks and knives became the new normal.

Read More Show Less
A mostly empty 110 freeway toward downtown Los Angeles, California on April 28, 2020. Robert Gauthier / Los Angeles Times via Getty Images

The shelter in place orders that brought clean skies to some of the world's most polluted cities and saw greenhouse gas emissions plummet were just a temporary relief that provided an illusory benefit to the long-term consequences of the climate crisis. According to new research, the COVID-19 lockdowns will have a "neglible" impact on global warming, as Newshub in New Zealand reported.

Read More Show Less
Centrosaurus apertus was a plant-eating, single-horned dinosaur that lived 76 to 77 million years ago. Sergey Krasovskiy / Stocktrek Images / Getty Images

Scientists have discovered and diagnosed the first instance of malignant cancer in a dinosaur, and they did so by using modern medical techniques. They published their results earlier this week in The Lancet Oncology.

Read More Show Less
Parks keep people happy in times of global crisis, economic shutdown and public anger. NPS

By Joe Roman and Taylor Ricketts

The COVID-19 pandemic in the United States is the deepest and longest period of malaise in a dozen years. Our colleagues at the University of Vermont have concluded this by analyzing posts on Twitter. The Vermont Complex Systems Center studies 50 million tweets a day, scoring the "happiness" of people's words to monitor the national mood. That mood today is at its lowest point since 2008 when they started this project.

Read More Show Less

Trending

The ubiquity of guns and bullets poses environmental risks. Contaminants in bullets include lead, copper, zinc, antimony and mercury. gorancakmazovic / iStock / Getty Images Plus

New York State Attorney General Letitia James announced Thursday that she will attempt to dismantle the National Rifle Association (NRA), arguing that years of corruption and mismanagement warrant the dissolution of the activist organization, as CNN reported.

Read More Show Less