AUG. 2 — Beneath the serene waters of Lake Michigan and other Great Lakes, a war rages. It pits armies of invaders bent on establishing colonies against a dwindling force of native lake dwellers. The invaders — at least 56 organisms not native to the Great Lakes — have infiltrated the lake over the decades, most of them arriving stealthily in freighter ballast tanks..
You’ve heard about the tenacious zebra mussel, which has cost industries on the Great Lakes billions of dollars over the past two decades to keep pipes open and water flowing through homes, businesses and power plants. You may have heard about its even more destructive cousin, the quagga mussel: It roams farther than the zebra and blankets nearly the entire lake bottom. Damage: unfathomable.
And … there are more lake pillagers likely to come. (See carp, Asian.)
We mention this because we just finished an impressive series in the Milwaukee Journal Sentinel, “A Watershed Moment: Can We Protect The Great Lakes From A New Wave of Invasive Species?”
The answer: gulp. History isn’t on our side. Nor do most people comprehend the staggering scale of what’s happening beneath the waves:
“The public can comprehend the devastation of a catastrophic wildfire that torches vast stands of trees, leaves a scorched forest floor littered with wildlife carcasses and turns dancing streams into oozes of mud and ash,” reporter Dan Egan writes. “But forests grow back. The quagga mussel devastation of Lake Michigan is so profound it is hard to fathom. … The mollusks now stretch across the bottom of Lake Michigan almost from shore to shore, piling on top of one another like a gnarly, endless plate of coral, clustering at densities exceeding 35,000 per square meter. People might still think of Lake Michigan as an inland sea full of fish. It’s now more accurate to think of it as an exotic mussel farm.”
So what? Here’s what: “We wear shoes while swimming or risk stinging, razor-sharp shell cuts. We buy exotic farm-raised tilapia instead of local fish such as chubs at our local grocery stores and restaurants. We turn up our noses and walk away from beaches fouled by rotting seaweed slicks triggered by the mussels and laced with their carcasses — often wrongly blaming the stench on sewage spills. We don’t even notice the hundreds of millions of extra dollars in utility bills we’ve paid to keep water pumping through everything from our power plants to our faucets.”
The mussel colonization of Lake Michigan has opened the floodgates for another invasive species, the round goby, a prodigious consumer of mussels — it crowds out the lake trout, white fish, sturgeon, herring and perch that welcomed European explorers to Lake Michigan.
One bright note: There hasn’t been another invasive species found in the Great Lakes since 2008, when a U.S. Environmental Protection Agency rule required oceangoing ships sailing into the Great Lakes to decontaminate ballast water. That’s the longest lull between invasive species discoveries since the St. Lawrence Seaway opened in 1959, Egan reports. Two possible reasons:
—There haven’t been any new species crafty enough to evade decontamination.
—Scientists aren’t looking in the right places … or “sleeper colonies” are skulking around the lake just waiting to be discovered when their numbers grow large enough to be readily detected.
There’s a rogues’ gallery of potential invaders on the government’s watch list. Those include the notorious Dikerogammarus villosus, aka the “killer shrimp.” Don’t laugh. The shrimp “makes a mess of ecosystems it invades by destroying native species with its vise-like jaws and then leaving them for dead, often without even swallowing a bite,” Egan writes.
Defending Lake Michigan against hordes of aquatic raiders is a grinding, long-term fight that requires constant vigilance. Not every invader harms the ecosystem. But this region’s most precious commodity, sloshing just outside your window, needs to be protected and safeguarded — from pollution, yes, but also from alien invaders.