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Lake Michigan is now clearer than Lake Superior — but why?

By Jake Allen/The Holland Sentinel • Oct 25, 2017 at 3:00 PM

Invasive qugga mussels are impacting the clarity of Lake Michigan and its ecology.

Clearer waters in Lake Michigan have opened up a whole new world for Craig Rich, a resident of Holland, who has been diving in the Great Lakes since 1971. 

Rich started diving on a consistent basis in Lake Michigan in 1988. He is also a founder of the Michigan Shipwreck Research Association, which has discovered about 20 shipwrecks since it was founded in 2001.

When Rich first started diving, he said he would not be able to see more than a foot with the naked eye or about 4 feet with a flashlight on a shipwreck at 120 feet deep in Lake Michigan. Now, Rich said you can go down to the same depth and see about 100 feet in front of you because clearer waters have allowed for more light to penetrate.

“It’s no longer kind of a scary, hostile environment,” he said. “It’s now a pleasant experience, and if you have the right kind of gear on, then it’s as beautiful as the Caribbean or any other warm-water place, except the water is very cold deep down in Lake Michigan.”

There is one trade-off, however. When Rich first started diving, he could see individual rivets and bolts in each shipwreck. Now the shipwrecks, except for the portions made of copper, are covered in quagga mussels.

Qugga mussels and clear water

According to Robert Shuchman, co-director of the Michigan Tech Research Institute, there is a correlation between the clearer water in Lake Michigan and an abundance of quagga mussel.

Lake Michigan and Lake Huron have surpassed Lake Superior when it comes to water clarity, Shuchman said. This is mostly due to the quagga mussels, which are invasive and were introduced to the Great Lakes in the mid-1980s via freighters from Europe.

They have taken over all the Great Lakes except Lake Superior, and Schuman said there are now just short of 10 trillion mussels in Lake Michigan alone.

“Quagga mussels are filter feeders,” Schuman said. “They are sucking the algae out of the water and that’s making the water clearer. If you are a fisherman or a kayaker, you may think you love clear water because you can see down 75 feet in some areas now of Lake Michigan, but it has negative ecological impacts.”

Ecological impacts

Although the clearer water looks nice, Shuchman is quick to warn about the ecological impacts of the quagga mussels.

“What that means is the very lower end of the food web is being eaten by these mussels, which could affect the whole food web including the fish producing revenue and fun for people in Lake Michigan,” Schuchman said.

Mike Sayers, a scientist with the Michigan Tech Research Institute, said the situation with the quagga mussels in Lake Michigan has the potential to be similar to the Lake Huron salmon fishery crash of the early 2000s.

The lowest portion of the food web could decrease to the point where the top of the food chain cannot be sustained, causing the whole thing to collapse, Sayers said.

Quagga mussels target the same food as alewife fish. Chinook salmon only eat alewife fish, so as alewives disappear so do chinook salmon.

“At this point in Lake Michigan the mussels have colonized almost the entire lake. Their existence is established,” Sayers said. “One of the questions that remains in the community is can these mussels, at their current abundances, survive.”

Sayers said it is possible for the mussels to run out of food sources and die off in large numbers, which could help the native plankton at the bottom of Lake Michigan’s food chain make a comeback.

However, Sayers said the mussels are very resilient.

“They will likely always at this point impact the ecology to some degree,” he said. “It’s just a matter of in what direction. They are not going to go away at this point.”

Preventative measures

The Michigan Department of Natural Resources and departments from surrounding Great Lake states have already started taking measures to prevent a food web collapse in Lake Michigan.

Sayers said the DNR has begun to stock less salmon in Lake Michigan as food sources for the salmon has decreased in the lake due to the presence of quagga mussels and the effect these mussels have had on the lower food chain.

“There’s not enough food for the top level predators, the salmon mainly, to survive at the levels they were being stocked,” Sayers said. “They have reduced the stocking in an effort to prevent a collapse.”

Captain David Engel, who has been charter fishing in Saugatuck for the past 40 years, said he has definitely noticed the water getting clearer on Lake Michigan. He said he has also noticed impacts of the DNR stocking less salmon in the lake.

“We are catching bigger fish, but less fish,” Engel said. “And the runs don’t last as long. They are not quite as easy as they were to catch. We have had to use different gear and longer lines to adjust because of the clearer water.”

As local fisherman and Lake Michigan visitors adjust, Sayers and Shuchman agreed it will be important to keep an eye on the all of the ecological impacts the quagga mussels could have on the Great Lakes in the years to come.

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