What color is your water? On Lake Erie, it’s still green

GIBRALTAR ISLAND — This year’s algal bloom on Lake Erie is shaping up to be the biggest on record. The water around the shores of popular vacation destination Put-in-Bay are a deep green due to the algae, 80 percent of it cyanobacteria which has the potential to release the toxin microcystin. But bigger may not be worse, at least in one respect.

“Not all algae are bad for lakes,” said Dr. Justin Chaffin, Research Coordinator, Ohio Sea Grant and Ohio State University’s Stone Lab, located on Gibraltar Island. “Algae produces about 50 percent of Earth’s oxygen. So every other breath you take, you can thank algae for that.”

Algae come in all different sizes and shapes. Algae are the base of the food web. On land, humans have secured the core of this chain. Dr. Chris Vandergoot, Supervisor with ODNR Sandusky Fisheries Research Unit, studies Great Lakes fish populations and their behaviors. He names the walleye as the apex predator of Lake Erie’s aquatic food web. Zooplankton eat algae, small fish eat the zooplankton and the big fish like walleye eat the small fish.

However, too much of the wrong type of algae is harmful. This type of occurrence is called a harmful algal bloom (HAB) in freshwater and red tides in saltwater. Microcystis is the type of cyanobacteria (blue-green algae) in Lake Erie’s open water, while planktothrix thrives in Sandusky Bay. The latter is also common in Grand Lake St. Marys. According to Dr. George Bullerjahn of Bowling Green State University’s Department of Biological Sciences, planktothrix was responsible for toxic algae bloom in Sandusky Bay, different from the microcystis that shut down Toledo’s water supply in 2014.

There are blooms occurring all around the world due to excess nutrients getting in the water. They have the potential to produce toxin or have harmful impacts on the ecosystem. These are the types of algae that have made the news.

According to Chaffin, a water temperature of 65 is warm enough for cyanobacteria, but nutrients are the main driver in HAB. These nutrients most often end up in the water via agricultural runoff, failed septic systems and combined sewage outflows. Factors that regulate microcystin production are phosphorus and nitrate values. “If it grows crops or grass, it grows algae,” he said. “Add in nitrogen and your bloom really takes off. Neither microcystis nor planktothrix can make mycrocystin without nitrate ammonia and urea.”

And even though there is a whole lot of the blue-green stuff in Lake Erie this summer — averages that are almost twice what the 2014 bloom was, said Chaffin — scientists are seeing much lower toxins on average compared to the 2014 bloom. This seems to indicate to researchers that the high total phosphorous and nitrate values recorded in June in Lake Erie are starting to settle down.

This is good news for drinking water, but that 80 percent cyanobacteria along and off Ohio’s northern coast is junk that’s not good for the fish. As blue-green algae flourishes, the diatoms at the bottom of the food web crash. Diatom-consuming zooplankton don’t eat cyanobacteria. Therefore, a crash in the diatom population affects the creatures further up the food chain, including smaller fish and walleye.

Not only does the overabundance of this junk have the potential to derail the food chain, it is already having a negative impact on this country’s economy. In 2006, blooms in U.S. cost the economy $2.2 billion per year. Lake Erie feeds a $12.9 billion tourism industry, and visitors have shied away this summer due to advisories and the smell of decomposing scums.

As of July 30, drinking water was reported to be safe in Toledo and southeast Michigan, both of which were affected by HAB toxins in 2014. There just may not be that many people around to drink it.

Next week: Scientists and farmers find answers as well as more questions.