Reconstructing the range expansion and subsequent invasion of introduced European green crab along the west coast of the United States

The European green crab, Carcinus maenas, was first documented in San Francisco Bay in 1989, and has since spread north along the west coast of North America. The spread of this invasion has not been a smooth expansion, which has raised questions about the underlying causes of variation in recruitment. We modeled larval development and transport along the West Coast by employing an individual-based model that incorporated oceanographic model output of water temperature and ocean currents at fine spatial and temporal scales. The distance that larvae were advected depended primarily on the timing of larval release. However, the effect of seasonal ocean currents varied across latitude and years. Our results imply that the furthest northern transport from California occurs when larvae are released from Humboldt Bay during the fall of an El Niño year, making this a particularly risky time for invasion to Oregon and Washington estuaries. To precisely predict future spread and potential impacts of green crab, we recommend further empirical research to determine the precise timing of larval release and seasonal abundance of green crab larvae from North American west coast populations.