May 25 2009
Seeing Zebras:
What to Do When Aliens Come to a Waterway Near You
You heard it here first: Canoe Country is under siege, and the Threat Assessment Team is hoisting the red warning flags. Their message? Enemy aliens are invading our waters. That sounds alarming, doesn’t it? And it is. How can we fight back? Let’s begin by spotlighting the poster boys of this alien invasion: the Dreissena twins, aka zebra and quagga mussels (Dreissena polymorpha and D. bugensis, to those in the know). These bad boys cling to boat hulls, pilings, and other underwater surfaces, multiplying shamelessly and displacing native mussels. The predictable result? Localized extinctions of native species. Moreover, the twin troublemakers infiltrate water pipes of every description, from municipal water-treatment intakes to power-plant coolant systems to the raw-water intake pipes on outboard motors. That’s not the worst news, however. Quaggas are also bioterrorists, known to harbor Clostridium botulinum, the organism responsible for botulism. Yellow perch chow down on quaggas—it seems that these popular panfish have developed a taste for the tiny mussels over the years—and then … you guessed it … the botulism organism moves up the food chain. I’ll bet you can also guess who’s at the top of the chain. Us, that’s who. This certainly puts the traditional shore lunch in a different perspective, doesn’t it? Bon appétit!
OK. That’s the threat scenario in brief. And just where did these alien invaders come from? No one is saying for sure, but it’s thought that the Dreissena twins were stowaways, hitchhiking from the Old World to the New in the ballast water of ocean-going ships. In any case, they were first ID’d when they established a forward outpost in the Great Lakes. But they weren’t content to stay put. They had big plans. They didn’t just want to move in. They were determined to take over. And they’re following through. In fact, they’ve already pushed inland as far as the Colorado watershed. How did they move so far, so fast? That’s painfully obvious. They’ve made unwitting collaborators of their natural enemies—boaters. Yes, you heard it right. People like you and me are aiding and abetting the enemy. So what are we going to do about it? Read more…
