Pictures: Extreme Algae Blooms Expanding Worldwide

Green With Algae

Image courtesy Jeff Schmaltz, MODIS/NASA

Tan fingers of sediment and green swirls of algae are visible in Lake Erie on March 21, 2012.

According to an April 16 study in the journal Proceedings of the National Academy of Sciences, scientists found that a whopping algae bloom in 2011 was caused by agricultural practices, warming temperatures, weak lake circulation, and heavy precipitation.

At its peak, the bloom covered 1,930 square miles (5,000 square kilometers) of the nearly 10,000-square-mile (25,600-square-kilometer) lake.

The study authors warned that such blooms would become a more frequent occurrence unless steps were taken to manage the lake.

Indeed, in the 2012 image by NASA's Moderate Resolution Imaging Spectroradiometer, heavy rains led to large amounts of runoff, and warm temperatures encouraged the blooms.

Published April 23, 2013

Green Gunk

Photograph by Peter Essick, National Geographic

A boat motors through a 2011 algae bloom on Lake Erie near Toledo, Ohio, in an image taken for an article on fertilizing the world in the May 2013 issue of National Geographic magazine.

In addition to causing numerous economic headaches for tourists and fishers, these blooms can also cause health problems.

Not all algae blooms produce toxins, said Caron, USC's harmful algal bloom expert. But for those that do, in freshwater systems the culprit is usually blue-green algae, or cyanobacteria. The common toxins some produce are called microcystins, he said. "They're very harmful to your liver." (Read about sea otters poisoned by microcystins.)

Common toxins produced by algae blooms in the ocean are neurotoxins that can—in high enough quantities—shut down a person's heart, stop their breathing, cause them to lose their short-term memory, or send them into convulsions, he added.

Published April 23, 2013

Brush Strokes

Photograph by Jianan Yu, Reuters

Two people row their way across algae-infested Chaohu Lake (map), China, in a 2009 picture.

Although the country has spent billions of dollars trying to clean up its waterways, China's lakes and rivers still host algae blooms that can turn the environs into a watercolor painting.

Researchers are still trying to figure out why some types of algae grow in some circumstances and not in others, said USC's Caron.

Understanding that would go a long way in being able to pinpoint which conditions could stimulate toxic blooms, and which would just produce a riot of colors. (Also see "'Crazy Green' Algae Pools Seen in Antarctic Sea.")

Published April 23, 2013

Plant Food

Photograph by Peter Essick, National Geographic

Farm workers spread fertilizer pellets on wheat fields in China in 2011. Overuse of these nutrients on farms is only one source of nitrogen and phosphorus entering the environment.

Sewage treatment plant discharges and runoff from urban neighborhoods are also large contributors, said USC's Caron. (Seepictures of urban environment issues.)

"Miracle-Gro has way more nutrients than your lawn can use, and that excess gets washed into the street," he explained. Then those nutrients make their way into the watershed, where they can trigger algae blooms.

Published April 23, 2013

Suffocated

Photograph by Tom Archer, NSF

This dead fish suffocated during the massive algae bloom in Lake Erie in 2011.

People aren't the only ones affected by massive algal blooms, and the consequences for organisms like fish can be fatal. If the blooms are thick enough, algae can clog their gills, reducing the animals' ability to take in oxygen and get rid of waste.

The blooms can also create dead zones: When the massive amounts of algae die, bacteria start to decompose the organic material, and in the process they suck all the oxygen out of the water. This leaves little oxygen behind for fish or other organisms to breathe. (Related:"World's Largest Dead Zone Suffocating Sea.")

Published April 23, 2013

Green Goo

Photograph from Reuters

A fisher cups algae-choked water from China's Chaohu Lake in 2009.

There are no easy fixes for algae blooms, said USC's Caron. Many times, the solutions people have come up with to eradicate an algae bloom just introduce new problems.

One technique that some have tried is sprinkling copper sulfate onto the blooms. Copper kills the algae, but the metal can also be harmful to other organisms, he explained. (Learn about copper sulfate.)

Other people have tried spraying fine particles of clay onto a bloom, which clumps up the algae. Once the clumps are heavy enough, they sink to the bottom, Caron said, where they settle on the sediment.

"The difficulty there [is] you're taking a potentially toxic algae that's spread out [on the surface] and concentrating them on the bottom," smothering bottom-dwelling organisms in toxic materials, he explained.

In any case, these are all temporary strategies—Caron isn't currently aware of any truly effective solution to treat algae blooms.

Education "and prevention are probably better strategies."

Published April 23, 2013

Healing

Photograph by David McLain, Aurora Photos/Corbis

Although blooms, such as the toxic algae bloom in California's Klamath River (above), are becoming more frequent, Caron is hopeful. Water systems are renewable, he said.

It's not like dealing with extinct animals, which can't come back, he explained. If we stop polluting waterways, eventually they'll heal. (Related: "America's Ten Most Endangered Rivers of 2013.")

"Recognizing what is wrong and what needs to be done to correct it is something that can be done," Caron said.

"It's merely a matter of figuring it out, and then having the political will to get those things done."

Published April 23, 2013