64 



2. 



9r«atly influence the way we use these systems, the benefits we 

 derive from them and the costs to society to extract those 

 benefits. . .i.v'' 



The urgency of the situation seems obvious. During just the 

 last decade, new species have appeared in the Great Lakes ecosystem 

 with visible impact. The public doesn't need scientists to tell 

 them these species are present. I'm referring primarily to the 

 spiny water flea ( Bythrotreohes eederstroemi^ , zebra mussels 

 ( Dreissena polvmorpha ^ and ruffe ffiymnocephalue jzfinma) . The spiny 

 water flea, or B.C. for short, discovered in 1984, quickly 

 displaced native zooplankton to become such a dominant species in 

 several of the Great Lakes that they accumulated on anglers' lines-. 

 Zebra mussels, discovered as two-year olds in Lake St. Clair in 

 1988 (IJC and GLFC, 1990) , have now expanded their North American 

 range to include the entire Great Lakes system, the Mississippi 

 River, Arkansae-White-Red Rivers, Ohio River, Mohawk River-Hudson 

 River drainage, and the Tennessee-Cumberland River systems (USFWS 

 1993). It is believed that this rapid expansion was vectored by 

 barge traffic in navigable waterways, but eventually other vectors 

 will introduce zebra mussels to the majority of surface waters in 

 the eastern United States. 



Damage from abundant zebra mussel colonies has been well 

 documented (Mills, etal, 1993). They physically displace native 

 mollusk species, clog water intake structures, foul vessel hulls 



