Modeling Larval Dispersal of Invasive Species in Lake Michigan

Knowledge of invasive species dispersal is key for early detection and rapid response. We studied potential dispersal of invasive ruffe and golden mussel (Limnoperna) larvae in Lake Michigan using a 3D particle transport model. Advection fields were derived from 10-year hydrodynamic model runs. We predicted larval transport from ballast release points located along major shipping lanes, ports (and vicinity), and major tributaries.  Ruffe larvae were released daily at surface from mid-April to mid-May and tracked for 7 days while Limnoperna larvae were released from mid-May to September and tracked for 70 days.  We targeted larvae settlement in nearshore waters: ruffe settles in waters < 10 m deep while Limnoperna settles in waters < 50 m deep. In mid-lake ballast releases, Limnoperna larvae drifted eastward (reflecting prevailing surface currents) and colonized nearshore areas on the east coast. In contrast, due to differences in seasonal and drift duration, dispersal of ruffe larvae was minimal, reducing chances of survival. Larvae released from ports and river mouths showed very small dispersal for both species, drifting only a few kilometers before settling (although Limnoperna spread was stronger). Dispersal was much stronger from ballast release locations near ports (5 and 10 km offshore), especially for Limnoperna.