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Increasing toxicity of algal blooms tied to nutrient enrichment and climate change
By David Stauth
CORVALLIS, Ore. – Nutrient enrichment and climate change are posing yet another concern of growing importance. Cause there’s an apparent increase in toxicity in water. That’s some algal blooms. Especially in freshwater lakes and estuaries around the world. All which threatens aquatic organisms. In addition, ecosystem health and human drinking water safety.
So yes. This nutrient enrichment, or “eutrophication” increases. All creating toxin-producing strains of cyanobacteria in harmful algal blooms. That’s what scientists saying.
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 to have produced the oxygen that paved the way for terrestrial life to evolve. They are highly adaptive and persistent. Furthermore, researchers say, today are again adapting to new conditions. That’s in a way that threatens some of the life they originally made possible.
A particular concern is Microcystis sp., a near-ubiquitous cyanobactecrium that thrives in warm, nutrient-rich and stagnant waters around the world. Like many cyanobacteria, it can regulate its place 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 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 supported by the National Science Foundation. “They’re the uninvited guest that just won’t leave.”
“When one considers their evolutionary history and 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,” he said. “For the most part, the best we can do is to try to decrease the conditions that favor their increase.”
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 United States, and based on the last EPA 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 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 retained over millions of years.”
Because of their buoyancy and the location of toxins primarily within the cell. Cause exposure risks are greatest near the water’s surface. Therefore all which raises concerns for swimming, boating and other recreational uses.
“We need to increase public awareness of these issues,” he said. As is clear and with a warming climate. With all comes rising carbon dioxide levels. So dams on many rivers are overloading of nutrients. Finally, then they flow into our waterways. Therefore the size and duration of toxic cyanobacterial blooms oy! Things are only getting worse.