The EPA plans to monitor mysis and other fish food. In areas of Lake Michigan where diporeia disappeared, white fish even began eating zebra mussels, which weren't very healthy for them, Nalepa said. He said the fish, whose guts became packed with shell material, were so skinny that fishermen could no longer get a fillet off them. It's just that, from a scientific standpoint, we will have a big void in the whole food web out here. If something happens to the alewives and smelt, then it's crunch time on trout and salmon.
Scientists say they fear the diporeia disappearance is just beginning.
Nalepa said he believes the decline of diporeia is related to zebra mussels, although in some cases, there is no obvious connection. In St. Joseph, Mich., where diporeia disappeared within six months in 1992, researchers had never found a zebra mussel, he said. But most disturbing is that there doesn't appear to be any way to stop the disappearance, Tuchman said.