Tahlequah Daily Press

March 8, 2013

Experts explain lake, river algae

By TEDDYE SNELL
Staff Writer

TAHLEQUAH — Spring is on its way, and it won’t be long before area residents take to the rivers and lakes to enjoy canoeing, fishing, swimming and other water sports.

Drought conditions, coupled with heavy spring rainfalls over the past two summers, have created the perfect environment for the blue-green algae blooms documented at Lake Tenkiller. These blooms pose a health risk to humans and animals, and point to what could be a larger problem for the health of the lake.

According to the Oklahoma State Department of Health, blue-green algae, also known as cyanobacteria, is a conglomerate of microscopic organisms that live in water. The algae are usually too small to be seen, but sometimes can form visible algae blooms.

Blooms can form in warm, slow-moving waters that are rich in nutrients, and generally occur in the late summer or early fall.

According to Tony Clyde, limnologist and reservoir biologist for the U.S. Army Corps of Engineers, Tulsa District, Tenkiller has a fairly long history of nutrient data collection in the watershed, which helps identify problem areas and the conditions in which the harmful algae prosper.

Despite efforts by groups like Save The Illinois River Inc. to reduce phosphorus loading in the Illinois River and Lake Tenkiller, long-term effects of nutrient loads in the area promote the growth of blue-green algae.

“The general theory is spring floods, paired with the drought, have allowed for nutrient conditions to be such that blue-green algae get a strong foothold in the lake,” said Clyde. “In reservoirs where there’s been a great deal of phosphorus loading, the environment gets unbalanced. The blue-green algae have the ability to fix atmospheric nitrogen, which then limits phytoplankton growth and the beneficial strains of algae die.”

According to the Oklahoma State Department of Health’s website, exposure to blue-green algae may cause a number of adverse health effects. Skin exposure can cause rash, hives or skin blisters. Inhalation of blue-green algae can result in runny eyes, runny nose, sore throat, asthma-like symptoms or allergic reactions. Ingestion can cause acute, severe stomach cramps, nausea, diarrhea or vomiting.

Clyde said due to the preponderance of BGA blooms in Lake Tenkiller and other area lakes, the Corps has developed a response procedure for disseminating information to tourists and lake enthusiasts.

“We’ll be monitoring Tenkiller again this year, probably beginning in April in preparation for the Memorial Day weekend,” said Clyde. “Visitors will want to check www.myoklakes.com for water conditions before traveling.”

Residents along the Illinois River recently reported seeing a red, clay-colored substance floating on the water in a backwash near the river. Ed Fite, Oklahoma Scenic Rivers Commission administrator, was notified of the sighting.

“This is a form of algae known as Rhodophyta, and does not present a hazard,” said Fite. “As a matter of fact, some strains of red algae have been used by the Japanese for thousands of years as a food source.”

According to a University of California-Berkely report, in Asia, rhodophytes are used to make nori, which is used in many forms of sushi. The high vitamin and protein content of this food make it attractive, as does the relative simplicity of cultivation.

Clyde said Corps was notified about red algae at Lake Tenkiller, as well.

“We had reports that came in to us on Feb. 6 about the red algae,” said Clyde. “The person reporting it said the substance on the surface of the water looked like transmission fluid, and this was a bloom of biblical proportions, so it can be somewhat alarming. It was at Deep Well Hollow Cove. We checked it out, and identified it as a dinoflagellate, which is in the same group of organisms that create the red tides along the coast that cause shellfish problems.”

Clyde said this particular species - freshwater blooms - was harmless.

“We collected samples on Feb. 6, and on Feb. 11, we notified our partners – the Oklahoma Conservation Commission, the Oklahoma Water Resources Board, the state secretary of health and others, that it’s not an issue.”

Clyde said the red blooms seem to appear more often in late winter and early spring.

“They do better in cooler water temperature,” said Clyde. “It’s probably nutrient-dynamic related, and something environmentally triggered it. It’s been a warmer winter in general, which may have also been a factor.”

Clyde also indicated the area is home to any number of different strains of algae, and while some may appear threatening, they are harmless.

“But the best rule of thumb is if you see something out of the ordinary, give us a call, and we’ll see that someone comes out and at least takes a look at it,” said Clyde. “Algae that is common to the Cherokee County area that might not pose a toxin threat would be the huge blooms of duckweed, which looks a little like floating leaves. It can bloom in upper backwater areas, and is pushed into larger bodies of water by rain.”

 

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