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National Centers for Coastal Ocean Science

The Rise of Cyanobacteria in Freshwater Resources

February 24, 2012
This image shows a bloom of cyanobacteria in Lake Erie on August 19, 2011 (courtesy of Thomas Archer).

This image shows a bloom of cyanobacteria in Lake Erie on August 19, 2011 (courtesy of Thomas Archer).

Cyanobacteria (formerly known as blue-green algae) are on the rise in the U.S. and worldwide, becoming a serious threat to freshwater resources and public health. Research results funded by the National Centers for Coastal Ocean Science are uncovering the secrets of why cyanobacteria are so successful. This information will be used to develop new strategies to control this growing problem.

What are Cyanobacteria?

Cyanobacteria are one of the oldest life forms on the planet, having been around for nearly 3.5 billion years. They were the first organisms to harness the sun's energy to make food, and they may be responsible for creating the oxygen in our atmosphere—a key ingredient for nearly all life on Earth.

These single-celled plants abound throughout the world. They live in fresh and saltwater and nearly every condition in between. Usually they provide food to organisms higher up on the food chain, in the same way that grass feeds insects on land.

But these tiny life forms also have a dark side. Many produce toxins that are poisonous to people and animals, causing illness and death to those who breathe, drink, or even touch too much toxin at once. Due to the impacts from blooms of cyanobacteria, water utilities require extra filtration to keep communities safe from noxious odors and flavors when huge underwater clouds of the species surround intake pipes. Swimming areas can close to protect public health. Livestock and pets that are exposed to blooms may die.

Responding to Outbreaks of Cyanobacteria

Researchers funded by the National Centers for Coastal Ocean Science are trying to better understand cyanobacteria and what makes them so successful to spur the development of countermeasures to address this problem.

Scientists have known that conditions must be just right for cyanobacteria to undergo a population explosion: the right nutrients, the right temperatures, specific salinity, as well as a lack of predators, and competition all play a role.

Humans, the study says, are improving the conditions that cyanobacteria readily thrive in. For some time, human-made sources of nitrogen and phosphorus encouraged larger blooms. Warming water temperatures caused by climate change actually does two things: it fuels cyanobacteria species while suppressing the growth of less harmful algae.

Over the years, policymakers have tried to address the problem by regulating how much phosphorus or nitrogen can get into waterways. Cyanobacteria require both of these nutrients for survival. There are some cyanobacteria that can manage with low levels of phosphorus and nitrogen or they may use forms of these nutrients that most algae cannot.

Cyanobacteria are not going away, but understanding what makes them so successful will lead to new methods of prevention and control.



Research findings presented in this article are based on the following publication: The Rise of Harmful Cyanobacteria Blooms: The Potential Roles of Eutrophication and Climate Change.