Geographic information system (GIS) analysis of ecosystem invasion: Exoticmussels in Lake Erie

Geographic information system (GIS) analysis with bathymetric, substrate, a nd side scan sonar (SSS) data was used to assess both spatial and temporal expansion of exotic dreissenid mussels onto sedimentary habitats in Lake Er ie. These data were used for developing multiple regression models with sub strate types and SSS data to interpret the expansion of Dreissena assemblag es across the central and western basins of Lake Erie from 1994 to 1998. Th e 1994-1996 GIS model predicted the 1997 SSS measurements of Dreissena cove rage correctly in 84% of the cases (n 50). Similarly, the 1994-1997 GIS mod el predicted the 1998 SSS measurements of Dreissena coverage correctly in 8 0% of the cases (n = 20). These models indicated that Dreissena coverage ra nged from <1% on muds in 1994 to 67% an sands and gravels in 1997. Based on all of the substrates, the 1994-1997 model indicates that Dreissena beds h ave been expanding since 1994 at 1,000 +/- 6 km(2) yr(-1) and presently occ upy 5,484 +/- 32 km(2) of the 25,734 km(2) sedimentary bottom of Lake Erie. Our observations indicate that expanding Dreissena beds are altering soft- substrate habitats and influencing the ecosystem dynamics throughout Lake E rie. Furthermore, this study demonstrates that the distribution, abundance, and ecosystem impacts of invasive species in other watersheds can be accur ately described and interpreted over diverse spatial and temporal scales,us ing GIS models.