A FORMERLY MOVABLE FEAST.

In the course of remarking on flamingos foraging on Lake Michigan, I noted, "I suspect flamingos will not find Wisconsin winters congenial, and zebra mussels are also filter feeders."  I'd forgotten about another filter feeder.  "The likely outcome will be a collapse of the whitefish population. But when the quaggas exhaust their food supply, the quagga population collapses? The article mentions a seaweed called cladophora that prefers clearer water. What is cladophora's food supply? What fish use cladophora for food?"

Before the quagga population collapses, many a hull and fuselage will collapse.

The Great Lakes’ frigid fresh water used to keep shipwrecks so well preserved that divers could see dishes in the cupboards. Downed planes that spent decades underwater were left so pristine they could practically fly again when archaeologists finally discovered them.

Now, an invasive mussel is destroying shipwrecks deep in the depths of the lakes, forcing archeologists and amateur historians into a race against time to find as many sites as they can before the region touching eight U.S. states and the Canadian province of Ontario loses any physical trace of its centuries-long maritime history.

“What you need to understand is every shipwreck is covered with quagga mussels in the lower Great Lakes,” Wisconsin state maritime archaeologist Tamara Thomsen said. “Everything. If you drain the lakes, you’ll get a bowl of quagga mussels.”

Quagga mussels, finger-sized mollusks with voracious appetites, have become the dominant invasive species in the lower Great Lakes over the past 30 years, according to biologists.

The creatures have covered virtually every shipwreck and downed plane in all of the lakes except Lake Superior, archaeologists say. The mussels burrow into wooden vessels, building upon themselves in layers so thick they will eventually crush walls and decks. They also produce acid that can corrode steel and iron ships. No one has found a viable way to stop them.

Remind me again, why did Our Political Masters sell the St. Lawrence Seaway as an internal improvement?

Quagga mussels, native to Russia and Ukraine, were discovered in the Great Lakes in 1989, around the same time as their infamous cousin species, zebra mussels. Scientists believe the creatures arrived via ballast dumps from transoceanic freighters making their way to Great Lakes ports.

Unlike zebra mussels, quaggas are hungrier, hardier and more tolerant of colder temperatures. They devour plankton and other suspended nutrients, eliminating the base level of food chains. They consume so many nutrients at such high rates they can render portions of the murky Great Lakes as clear as tropical seas. And while zebra mussels prefer hard surfaces, quaggas can attach to soft surfaces at greater depths, enabling them to colonize even the lakes’ sandy bottoms.

After 30 years of colonization, quaggas have displaced zebra mussels as the dominant mussel in the Great Lakes. Zebras made up more than 98% of mussels in Lake Michigan in 2000, according to the University of California, Riverside’s Center for Invasive Species Research. Five years later, quaggas represented 97.7%.

For wooden and metal ships, the quaggas' success has translated into overwhelming destruction.

The mussels can burrow into sunken wooden ships, stacking upon themselves until details such as name plates and carvings are completely obscured. Divers who try to brush them off inevitably peel away some wood. Quaggas also can create clouds of carbon dioxide, as well as feces that corrode iron and steel, accelerating metal shipwrecks' decay.

There's less calcium in Lake Superior's water, which makes that lake less conducive to anything with a shell.  Unfortunately, any quest to introduce a natural predator for quaggas, as some people contemplate, is likely to have unintended consequences of its own.