Ship-borne nonindigenous species diminish Great Lakes ecosystem services

We used structured expert judgment and economic analysis to quantify annual impacts on ecosystem services in the Great Lakes, North America of nonindigenous aquatic species introduced by ocean-going ships. For the US waters, median damages aggregated across multiple ecosystem services were $138 million per year, and there is a 5% chance that for sportfishing alone losses exceeded $800 million annually. Plausible scenarios of future damages in the US waters alone were similar in magnitude to the binational benefits of ocean-going shipping in the Great Lakes, suggesting more serious consideration is warranted for policy options to reduce the risk of future invasions via the St. Lawrence Seaway. © 2012 The Author(s).