Study Makes Dire Prediction of Water-Fouling Algae Growth In Lake Erie

Block News Alliance
17 December 2015
By Tom Henry

Lake Erie appears unlikely to avoid massive algal blooms over the next several decades because of how climate change “supercharges” it like steroids, according to a new report Wednesday.

A pair of scientists presented that prediction in San Francisco at the American Geophysical Union’s annual conference.

Under at least one climate model, Lake Erie’s number of severe blooms “will likely double over the next 100 years,” said a statement released by Ohio State University in conjunction with their presentation.

The presentation by Noel Aloysius, a postdoctoral researcher in OSU’s aquatic ecology laboratory, and Hans Paerl, a distinguished professor at the University of North Carolina-Chapel Hill, hit on familiar calls for tighter controls on farm fertilizers and other forms of nutrient runoff, but also underscored the complexity of the problem as Earth’s climate continues to warm.

The pair are at the midpoint of a two-year study, the first to combine global climate change models with a watershed model. Their focus has been on western Lake Erie, especially the Maumee River watershed.

They have used the most recent data from the Nobel-winning Intergovernmental Panel on Climate Change. NOAA oceanographer Rick Stumpf, who’s in charge of that agency’s annual forecasting for Lake Erie, has led the study’s bloom-prediction model.

One of their take-home messages, Mr. Aloysius said, is that policymakers need to include climate-change predictions more in planning because they can no longer rely on historical trends.

“Climate change causes a synergistic effect,” Mr. Paerl said, explaining that Lake Erie’s most troublesome algae, which is actually a form of cyanobacteria called microcystis, thrives in warmer climates.

That type of algae is 3.5 billion years old, one of the oldest living organisms on Earth. But climate change and poor land use have helped it grow across the world, from the Arctic Circle to South America, during the past 20 years.

Warmer temperatures “essentially play in the playbook of these bacteria,” Mr. Paerl said. “They’ve seen it all. It can get warmer and they’ll like it even more.”

Mr. Paerl, who has made more than a dozen research trips to China lasting a month or longer, made several comparisons between Lake Erie and China’s third-largest lake, Lake Taihu, a source of drinking water for 10 million people.

Lake Taihu is five times smaller than Lake Erie and nine times shallower, making it more susceptible to algae.

But it is seen as “a great test case for algae problems that the United States will likely experience in decades to come,” according to OSU’s statement.

Lake Taihu had much shorter seasonal blooms like Lake Erie several years ago. In recent years, though, its blooms have lasted nine months of the year.

In May 2007, in China’s Jiangsu province near the city of Wuxi, a massive bloom of toxin-producing microcystis made drinking water unsafe for 2 million people for more than a week.

The situation there was similar to what happened in western Lake Erie in 2014, when a highly toxic bloom of microcystis made tap water unsafe the first weekend of August for the Toledo metro region’s nearly 500,000 customers.

“It’s exactly the same genus we see in Lake Erie,” Mr. Paerl said of Lake Taihu.

Jay Martin, an OSU ecological engineering professor, agreed in an OSU release that government agencies need to do more than look at historical records when setting guidelines for nutrient reductions.

He and others said the goal of reducing nutrients into western Lake Erie by 40 percent by 2025 may not be enough.

“Right now, we can only make recommendations based on the past, but the climate is not a constant. We need to look to climate models of the future to protect water quality in Lake Erie and around the world,” Mr. Martin said. “Maybe 40 percent is not enough of a reduction.”

The reduction targets are based around the most common nutrient, phosphorus. The amount of phosphorus in the water column readily available to algae dictates how large blooms will be.

But Mr. Paerl said more focus needs to be made on nitrogen, another common nutrient, because the amount of it often dictates how toxic the blooms are. Nitrogen, unlike phosphorus, is dispersed in both water and air. It is airborne in coal-fired power plant emissions and settles on the water.

The Block News Alliance consists of the Pittsburgh Post-Gazette and The Blade of Toledo, Ohio. Tom Henry is a reporter for The Blade.