The Cancer Of The Great Lakes: The Invasion Of The Zebra Mussel

“People look at the lake and don’t think of it as having a geography. It’s just a flat surface from above—and from there it looks pretty much the same as it did 30 years ago, but under water, everything has changed.” The invasion of the zebra mussel—and later, its cousin, the quagga mussel—have had a catastrophic effect on the Great Lakes, the largest body of freshwater in the world. Lakes that were once teeming with whitehead, trout, and other fish are now devoid of almost everything except mussels and goby fish (another invasive species). 

Ballast water is used to keep ships steady as they travel, especially those with less than full cargo loads. The nice thing about using water, rather than iron, as ballast is that it can be pumped in and out as needed. The not-so-nice thing about using water as ballast? Scientists found that ballast tanks "were basically floating ecosystems, swarming with life sucked up from ports across the globe". Because of a loophole in legislation, those ecosystems could be dumped into the Great Lakes on arrival, which leads to the introduction of a new invasive species every eight months. Zebra mussels and their compatriots have led to a chain-reaction of lake death from zooplankton to prey fish to birds, and "the chaos this has brought is like nothing the lakes have suffered in their 10,000 year history".

But there is a potential solution to stop the influx of aquatic invasives. "There is, literally, a door through which every foreign ship must pass before arriving at the dozens of ports rimming the Great Lakes’ shores: the St. Lambert Lock at Montreal. Every ship—and every one of the Great Lakes invaders it may be carrying—has to squeeze through this 80-foot-wide pinch point." This story walks you through a dizzying array of ecology, history, politics and economics in the most wonderful way. It is a long read, but well worth the time.