Sandusky Bay mystery solved?

SANDUSKY — Sandusky Bay's biggest mystery may have been solved. The harmful algal bloom in Sandusky Bay apparently is gone. And after years of research, a BGSU scientist, George Bullerjahn, thinks he's finally figured out why. There's been a lot of publicity about the harmful algal bloom in Lake Erie, but in reality, for years there were two blooms, a main bloom that takes up large areas of western Lake Erie, and a separate bloom in Sandusky Bay. And then there was one The main algal bloom is still with us. As of a few days ago, it was in Maumee Bay and nearby areas. That bloom is produced by a cyanobacteria, Microcystis, that can generate toxins that contaminate the lake water. Cyanobacteria is a bacteria in the lake water that resembles algae. It uses photosynthesis, just like plants. Until recently, a different kind of cyanobacteria, Planktothrix agardhii, generated its own harmful algal bloom. But the last full-fledged Sandusky Bay harmful algal bloom was in 2018. In 2019, it was much less, and in 2020 Planktothrix and the toxic bloom it produced was gone completely, replaced by cyanobacteria and algae that produce no toxins and pose little health hazard. Thanks to the departure of the Planktothrix, people can water ski in Sandusky Bay without having to worry about toxins being blown in their face, Bullerjahn said. Cracking the code While Bullerjahn previously had noticed that the bay's harmful algal bloom was gone, he and other scientists were still trying to figure out what happened. One scientist told the Register in 2022 that it was a "really exciting mystery." Bullerjahn believes the October 2018 removal of Ballville Dam, near Fremont on the Sandusky River, is the reason harmful algal blooms have gone away in the bay. The dam was removed to improve fish spawning and habitat, but it apparently also caused the Sandusky Bay changes in 2019 and 2020. Bullerjahn believes the reservoir created by the dam had a large amount of Planktothrix, and that the reservoir seeded a harmful algal bloom in Sandusky Bay. After the dam was removed, core samples were taken in the former lake bed. DNA tests revealed plenty of Planktothrix and also revealed the toxin produced by the cyanobacteria, bolstering the theory. Bullerjahn is a local expert on algal blooms in Sandusky Bay, although his expertise is sought worldwide; he has jetted to Africa to study harmful algal blooms in Lake Victoria and gone to China to participate in workshops. As an emeritus professor on the main campus, Bullerjahn no longer teaches classes, but he still carries out research and brings in grants. His formal scientific paper identifying the Ballville Dam removal as the cause for Sandusky Bay's improvement in water quality, co-authored by BGSU students, came out in May. Checking in-person Bullerjahn's findings are bolstered by years of intensive research in Sandusky Bay, including samples that go back for years. This year, Bullerjahn hired six BGSU students to go out and take samples. To illustrate how that research takes place, BGSU invited journalists last week to go out on Sandusky Bay on the Ziggy, a BGSU research boat based at Clemons Boats in Bay View. With Bullerjahn and two journalists were the boat's pilot, Frank Schemenauer, and three of the students, Grant Hayden, 22, a microbiology major from Centerburg; Ethan Edelbrock, 21, a biology major from Pemberville, and Margaret Rettig, 22, Marblehead, a marine aquatic biology, conservation biology and data science student who has just obtained her bachelor's degree. The boat moved from one sampling location to another as the three students took samples and measurements. Measurements and samples are taken at 10 different locations. They used instruments to check characteristics of the water, such as how clear it is and how much dissolved oxygen it has, and took water samples that can be tested for algae and algae toxins. Some samples containing algae and sediment were placed in a liquid nitrogen container on the boat's deck that has a temperature of minus 171 degrees Celsius. Those flash frozen samples are then put in a freezer. "It's a snapshot of that day, forever," Bullerjahn said. Bullerjahn also stopped the boat under Edison Bridge to point out a solar-powered instrument array that BGSU installed under the bridge. One instrument measures various characteristics of the water and transmits information every 20 minutes via the internet. Another measures water currents and their speed. That Edison Bridge instrument array is just one location of many buoys and instrument locations that provide information for many locations on the Great Lakes. Once ashore, Bullerjahn pulled out his laptop and showed how much of that information is publicly available on a colorful map at the Seagull website, seagull.glos.org.