In Shock Over Shells

They're coming. They were discovered only two years ago and already they have:

?Caused a partial shutdown of Detroit Edison's largest power plant.

?Forced a Michigan hospital to dismiss patients and cancel elective surgery.

?Threatened to destroy some game-fish spawning grounds in Lake Erie.

?Shut down the water supply to Monroe, Mich., for two days.

?Cost Detroit Edison, which provides electricity for nearly two million customers in southeastern Michigan, $500,000 a year in increased maintenance costs.

?Threatened boaters on Lake Erie by sinking navigational markers.

?Infested the water supply facilities of Cleveland and Detroit and several smaller cities.

In the next few years they may:

?Strip the microscopic phytoplankton, a basic element in the freshwater food web, from Lake Erie.