Scientists Combat Algal Blooms

It’s been called Return of the Green Slime. Gobs of algae have become more abundant over the past ten years in the Great Lakes, and especially in Lake Erie. But these algal blooms aren’t just a nuisance. They disrupt the ecosystem, hurt local economies, and can pose a serious health risk.

In the 1960s and 70s, a huge growth of blue-green algae invaded the Great Lakes. The green muck accumulated on shorelines, damaged water quality and kept swimmers away. The cause of those algal blooms was an abundance of phosphorous. Phosphorous is an essential nutrient for algae, which comes from agricultural run-off and laundry detergents. Government regulations in the 70s then limited the amount of phosphorous, and the algae receded.

Now, the algae appear to be back. Ohio State University Biology Professor David Culver studies blue-green algae. He says although the current amount of algae is only half of what it was 40 years ago, its sudden abundance is worrisome.

“Because there’s a lot less phosphorous coming in from the watershed, we’re surprised to see as much and as frequent algal blooms as we have now. And so we’re concerned, and that’s why there’s the fuss,” Culver says.

Culver suspects the arrival of non-native species of mussels might be causing the blooms. In the 1980s, the zebra mussel and its cousin, the quagga mussel, made their way into the Great Lakes. The mussels secrete nutrients that encourage algae growth.

Blue-green algae are actually bacteria, called cyanobacteria, and pose a serious problem.

“Number one, the cyanobacteria in general are not good food for the zooplankton, so they don’t contribute to the food-web that raises up to fish and thus to humans. And number two, many of the cyanobacteria produce toxins,” says Culver.

Currently, the most common toxin produced is called microcystin. It damages the liver and can cause rashes when in contact with skin. In 1996, 52 people died from microcystin in Brazil. They were kidney patients undergoing dialysis with contaminated water.

Partly because it’s shallow and warm, Lake Erie has experienced especially significant algal blooms. Lake Erie also supplies drinking water for Toledo, Cleveland, and much of northern Ohio. OSU Environmental Engineering Professor Hal Walker works on developing technology to treat algae. He says if nothing’s done to monitor and treat the algae, the toxin can easily make its way into tap water. Algal blooms are a huge issue because they occur everywhere there is surface water, which accounts for about half of the general population’s drinking water.

But, technology is available to solve the problem – one of which is activated carbon. Large carbon particles stick to the toxin, and then are filtered out. Most cities use this method. While agreeing it’s a problem, Walker doesn’t think algal blooms are a real crisis.

“No I don’t think it will be a big crisis, but it’ll cost money. With drinking water there are always sort of two issues: one, is technologyt available? And two, can it be implemented in a cost-effective way,” Walker says.

Still, Walker says continuing research is necessary to understand the effects of and treatments for algal toxins.

Perhaps the most significant impact is ecological and economical.

Algae can settle in cold water deep below the surface where it’s dark. Without sunlight, it can’t undergo photosynthesis and replenish the oxygen supply. The result is regions in the lake where there’s little to no oxygen. Scientists have dubbed these regions dead zones.

These dead zones harm the ecology of the lake, and in particular, dead zones destroy fish habitats. Culver says the loss of fish habitats hurts sport fishing, one of Lake Erie’s major industries.

“It’s been shown that there’s a multi-million dollar impact of sport fishing on the people living around the lake, because it’s such a good fishing lake,” says Culver.

Columbus and surrounding areas get their drinking water from nearby reservoirs. Rod Dunn is Supervisor of Water Quality Research at the Water Quality Assurance Lab of Columbus. Dunn says although there are algal blooms in central Ohio reservoirs, toxins like microcystin are not a problem.

“Different times of the year we see blooms, but usually it’s not the kind that produce algal toxins, and those just occur in real low numbers,” he says.

Dunn says the primary problem in Columbus from algae is taste and odor, but that can be treated.

Last month, the Michigan Environmental Council issued a report on the harmful impacts of algal blooms in the Great Lakes. The report also cited phosphorous from fertilizer and dishwasher detergents as reasons for algal blooms.