14 Aug 2007

Invasion of the Sideswimmers

Dear Blue Lobster:

I was was in a boat on Lake Erie and I threw a bucket down on a 150ft. of rope and dredged for a while. I wanted to see if I could find any Zebra Mussels. I found some, as well as a strange white crustacean that looks like a cross between a shrimp and a water flea. What the heck! I had no idea anything like that lived in the lake. I will never go swimming here again. What was it?


Dear Gentle Sir:

What you encountered was Gammarus tigrinus, commonly known as the Sideswimmer. This species is native to the North Atlantic Coast but has been introduced to the Great Lakes in the last decade in a controversial effort to limit the Zebra Mussel population.

Instead, the Sideswimmers have joined the mussel in the benthic zone of the lake, feeding upon valuable plankton. Fish populations, such as the small mouth bass, are in a freefall thanks to this meddling by scientists.

One positive aspect of the infestation of this invasive species is that the lake, heavily polluted by post-World War II industry and subsequently cleaned up by the Zebra Mussel in the Eighties, is now even more pristine. Thanks to the Sideswimmer, you can now enjoy a glass of water straight out of the lake.

Measures to control the Sideswimmer population are in order. A genetically engineered virus is being tested that would render adult Sideswimmers infertile. Wildlife officials are also stocking a Bluegill/Pumpkinseed hybrid (Lepomis gibbosus × macrochirus) in hopes it will eat the Sideswimmer.

As these silent underwater wars go on, rest assured the lake is still safe to swim in. These tiny creatures generally don't come to shore, instead preferring the dark silence of the bottom. Perhaps you'd like to take the Sideswimmer home and study them, along the some Zebra Mussels, in your aquarium!

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