Regional differences in rates and patterns of North American inland lake invasions by zebra mussels (<i>Dreissena polymorpha</i>)

Abstract

Zebra mussels (Dreissena polymorpha) have spread rapidly in North America by dispersal within connected bodies of waters. This study provides the first systematic evaluation of rates of zebra mussel dispersal to inland lakes separated from source populations by functional dispersal barriers. Plankton samples were examined for this exotic species from 140 lakes during a 3-year period (1995-1997). Infestations were detected in 19% of lakes surveyed: seven of 28 Indiana lakes (25%), 15 of 49 Michigan lakes (31%), but only five of 63 Wisconsin-Illinois lakes (8%). Annual rates of infestation varied from 0 to 12%·year-1 among the three regions. Wisconsin-Illinois lake infestations were only detected in 1995 and 1996, whereas new Indiana and Michigan infestations were detected in all three years. Lakes with surface areas less than 100 ha had lower infestation rates than larger lakes. Incidental sightings of inland lake colonization within the study region qualitatively supported observed regional differences in...