Disruption to that system can have dire consequences to its inhabitants, and that means paying attention not only to what is living in the water but on keeping unwelcome predators out.
"So one of the things that we know about invasive species is that they, they tend to get into an ecosystem, such as the Great Lakes. And they, they wreak havoc," said Jeffrey Zuercher, project manager at the US Army Corps of Engineers Chicago District. "It causes a lot of damage to the ecosystem, things that we don't want to have happen over time. And we want to make sure that they stay out because it helps keep the natural, keep system working, and it is protects the natural fish and other species that are already in the Great Lakes."
Asian carp are one species of invasive fish. They grow fast, jump high and have invaded many parts of the Mississippi River Watershed, wiping out native species. Scientists have creeping fears of Asian carp moving into the Great Lakes. They are concerned about the damage they could do to the natural biodiversity of the lakes, and the region's $7 billion fishing industry.
"The big head and the silver carp are bottom feeders, they start at the bottom of the food chain they consume. They consume the, you know, all this stuff at the bottom, and they were brought over from Asia to help out with fish bar in the southern states," Zuercher explained. "And they were brought in so they can take care of all the algae and other things that grow in fish was a really great idea at first, because it helped the fish farmers. And they were supposed to be not able to reproduce, when they brought them over."
That turned out to not be true. Whether it was a myth or whether nature found a way remains unclear.
"And they escaped from these fish farms and somehow were able to get into the Mississippi River. Since then they've, they've been voracious eaters they eat lots of, lots of food in a day. And they're able to reproduce like crazy," Zuercher said.
Asian carp started taking over the Mississippi River in the 1970s, and it wasn't until the early 2000s that they migrated north into the Illinois River, exploding in population. They now account for 90 percent of the river's total biomass, and they are slowly trying to migrate farther north.
Currently there is only one form of defense keeping the carp out of the Great Lakes -- an electric fence in Romeoville.
"And so what it is we put electricity in the water, and that electricity interacts with the fish's body and helps them to turn around and go back. We are maintaining that electrical charge in the water 24 hours a day seven days a week," Zuercher said.
A new wave of action came in December 2020 to prevent the invasion of Asian carp. A bill passed in the U.S. House to provide 80% federal funding for a new barrier to keep invasive fish out of Lake Michigan.
The project centers around the Des Plaines River in Joliet. A multiphased project at the Brand Road Lock and Dam by the Army Corps of Engineers will keep the carp from getting that far north, and keep them out of Lake Michigan.
"We're going to use air bubbles to get them out between the barges, we'll be having sounds. As we mentioned, they react to motorboat sounds. We're going to use that against them, we're going to try and drive them away with sound, and then we're also going to use electricity again. So we think that the combination of those technologies will help prevent them from getting into the lock," said Zuercher.
The project in Joliet comes with a hefty price tag, but funding of this bill by the U.S. House is crucial for the health of species native to the Great Lakes.
There is an abundance of pressure to put preventative measures in place to preserve this natural resource. According to National Geographic, more than 180 species with reproductive populations continue to threaten the Great Lakes Basin.
Another invasive species in Lake Michigan that's creating unusual impacts and causing irreversible damage is mussels.
"So, like the zebra and quagga mussels came here in the 80s. They've been here quite a while now. Interesting thing, as most people know about zebra mussels, they probably heard about zebra mussels, and how they clog intake pipes, they cover on the watch and boats and stuff like that and create a major news, when a lot of people don't realize is quagga mussels are a close cousin of the zebra mussel but it's actually a superior competitor," said Phil Willink, fish biologist. "So it does the same things as a zebra mussel does but it's better at it, and is almost completely replaced zebra mussels in Lake Michigan when I go out there I barely find zebra mussels anymore they're gone. Part of the problem with water, is that they filter water, they're very tiny, they're probably you know no bigger than my thumbnail basically."
Willink explained it is very difficult to eradicate invasive species once they move in considering the speed at which they spread.
"Going onto the bottom of the lake, and it is completely covered for miles and miles and miles with quagga mussels," Willink said. "We are hard pressed to find a clear space this big on the bottom of Lake Michigan. We've been out there for days. And so there are more invasive species, and I think most scientists need to realize that, I would say, that the impact is even greater than most scientists even realize. And so that has been a problem and it has sort of confounded a lot of the things they do that we do."
A new innovative method to remove quagga mussels is on the horizon. There are experimental treatments in Lake Michigan near Sleeping Bear Dunes. The Invasive Mussel Collaborative released video showing their latest technique of applying zequanox, a pesticide that targets quagga mussels. It's injected underneath anchored tarps placed directly on the reef. A 95% reduction in mussel density was found in the weeks following the applications.
"Well, invasive species can be game over for the Great Lakes," said Joel Brammeier, president and CEO of the Alliance for the Great Lakes. "Like I said, when you get a new invasion coming into the Great Lakes, there's no turning back the clock. We'd love to go back to the early 80s before the zebra mussels got in and do things differently so that invasion didn't happen, we can actually see the Asian carp coming literally toward Lake Michigan. And so we've got a great opportunity to stop them from getting here. And again, and it would be unconscionable for them to actually get in while we stand by and do nothing. I don't think that's going to happen we still have a really strong shot keeping them out."