BGSU researchers study beneficial winter algae

03 February 2011

Bowling Green State University researchers study diatom algae -- a winter species that they believe has a positive effect on the food web -- aboard the U.S. Coast Guard ship Neah Bay.

Bowling Green State University researchers study diatom algae — a winter species that they believe has a positive effect on the food web — aboard the U.S. Coast Guard ship Neah Bay. (PHOTO SUBMITTED BY JASON KEMPTON)

PORT CLINTON — When Mike McKay noticed pockets of brown water as a Canadian Coast Guard cutter broke through Lake Erie ice, he assumed mud had clouded the water.

When McKay and other researchers aboard the ship examined water samples, they realized the brown water was filled with a cold-water type of algae.

"To find these massive accumulations is a bit of a surprise," said McKay, director of Bowling Green State University’s marine program and Ryan professor of biology. "We’re seeing this all across the lake, most abundantly in the Central Basin (which stretches from Sandusky to Erie, Pa.)"

The algae, called diatoms, form long chains and thrive in cold water.

And unlike the toxic blue-green algae that exploded on Lake Erie and inland lakes with a slimy muck during recent years, diatom algae are mostly beneficial to Lake Erie’s food web, McKay said.

The BGSU group first noticed the diatom algae during winter 2007 and since then has seen masses of it throughout the lake during the winter. But that doesn’t mean this is a new type of algae, he said.

Few agencies monitor the Great Lakes during the winter months, so the diatom algae could have been present in Lake Erie long before McKay’s group discovered it, he said. And it has been found on the ocean and in the deepest lake in the world, which is located in Siberia, he said.

"We find it in polar environments associated with sea ice," he said. "It’s a cold-water species. Once the lake warms up, we don’t find this kind of algae abundance in the water anymore."

The diatoms appear to form near or with the ice, likely to take advantage of what little sunlight comes through, he said. It’s possible the algae helped form the ice as sort of an anchor to it.

"These algae don’t swim," McKay said. "(Without the ice) they’d sink because they’re fairly heavy."

Organisms that eat the algae ultimately become food for larger species, thus providing sport fish like walleye and perch with a good winter food supply, he said.

But the diatoms do have a downside.

When most algae — including diatoms — die off, they sink to the bottom of the lake and contribute to dead zones often found during late summer in the Central Basin, said Jeff Tyson, fisheries biologist supervisor for the Ohio Department of Natural Resources, Division of Wildlife, Fish Research Station in Sandusky.

Dead zones are areas of deep water where little oxygen is found, and they do not provide good habitat for bottom-dwelling species that often are part of the food chain, McKay said. They form when bacteria decompose dead algae and use up oxygen in the water in the process, Tyson said.

"It’s a lost area of production," Tyson said. "It’s lost habitat."

Animals like mayflies, which burrow in the muck on the lake bottom before hatching, cannot live in the dead zones, McKay and Tyson said. Larval mayflies provide a good food source of food for fish, he said.

Some organisms do persist in the low-oxygen areas, Tyson said.

"They’re of much lower quality from a food-web standpoint, and they’re smaller critters," he said.

In other lakes, the breakdown of dead algae wouldn’t cause problems, McKay said.

"But Lake Erie has a strange shape to it where the bottom waters are cut off from the Western and Eastern basins," he said.

This shape helps keep water at different depths and temperatures from turning over and circulating in the summer, McKay said.

"It’s really a stagnant pool," he said. "When we hit fall, and waters cool, they mix."

This causes the water to turn over and eliminates the dead zones, McKay said. The size of the dead zones varies each year, Tyson said.

Last year, researchers noticed an extensive dead zone that could be attributed to the blue-green algae blooms, Tyson said. Researchers believe the increase in that toxic summer algae is connected to high phosphorus levels in the lake that probably come from fertilizer and farm runoff, he said.

Meanwhile, BGSU has devoted classes and research to find out more about the mysterious diatom algae and the dead zones, McKay said.

Initially, the work started as a project involving McKay, colleagues from other schools and graduate students. Now, with the help of funding from Ohio Sea Grant and the Lake Erie Protection Fund, the research includes undergraduate students and a general science class of U.S. Coast Guard officers aboard the ship Neah Bay.

McKay and Coast Guard Lt. Commander William Woityra, who is the commanding officer of the Neah Bay, teach the class. The crew takes water samples while the ship opens the Lake Erie ice for commercial ships and logs its findings to help learn more about the diatoms and their impact on the lake.

"If it wasn’t for the strange basin format of Lake Erie, I think they would only be held up as a good algae," McKay said.