by Tim Thein
With the biggest of the world’s freshwater lakes in our backyard, one would think the effects of climate change would be slow and not noticeable in the Great Lakes region.
But there are many people studying these effects, and they have found that since the 1980s, there have been noticeable changes at the microscopic level of climate change present in the Great Lakes.
The first changes that are noticeable are at the microscopic level of diatoms, said Sarah Erickson, the education director at the Great Lakes Aquarium. Diatoms are single-celled algae that have a cell wall of silica. In other words, algae are really small organisms that live in the Great Lakes system. Algae can also be found all throughout the world. The reason the scientific community here is concerned about a change in the Great Lakes, according to Erickson, is that it reflects the sudden change that the world is warming up.
Scientists study the bottom of the Great Lakes to investigate the effects of the warming water, which is more common throughout the system. The aquarium’s educational display identifies the process: The bottom of the lake is a timeline of what has happened in the lake. Every year the lake has a life cycle. The water warms and cools with the change of the seasons. The diatoms die off and fall to the bottom. Scientists can study the very thin layers and get an estimate on the rate that the diatoms die off. They can be very accurate - within the last 400 years. Since the 1980s, these layers have shown rapid growth in certain diatoms and the shrinking of other species of diatoms because of the growth or expansion of other diatoms.
The algae that scientists are most concerned with is the rapid expansion of Cyclotella, which has evolved dramatically since 1813. Cyclotella compete with other organisms for the same food. Some other species are appearing less and less abundant since the 1980s.
Over time, the “data show that the air temperatures are changing,” Erickson said. Climate change is not achieved overnight, but over a long period of time. Erickson explained that diatoms play a role in the food chain. Any changes higher up in the food chain are not noticeably different yet, but the scientific community is interested in following those changes and outcomes, she said.
UW-Superior student Brandon Barnes, 23, has been a Lake Superior recreational sports fisherman since childhood. “I have noticed the behavior in the fish has changed,” he said. “When I was a child, I was able to catch a lot more fish. Now I am lucky if I catch one or two, if any, fish at all.”
Barnes believes climate change is happening. He is worried about the future of fishing in the next 20 to 40 years; whether fishing will be a forgotten Great Lakes activity. He hopes we can slow the changes by burning clean energy and limiting our carbon emissions, caused by fossil fuel.