The Great Lakes are subject to multiple stressors, and assessing their impacts is challenging when these stressors have different spatial distributions and their impacts vary among habitats. The ability to map the presence or intensity of individual stressors across the Great Lakes, weight individual stressors for their impact, and combine multiple stressors into an integrated total impact map could significantly enhance our ability to manage and restore the Great Lakes ecosystem. Here, we report results based on 34 individual stressor layers mapped at a 1-km2 resolution across the surface of the five Great Lakes, and we evaluate levels of cumulative stress at locations where lake-derived ecosystem services are present (e.g., recreation, food, biodiversity protection). Individual stressors represent seven broad categories, including climate change, invasive species, coastal development, land runoff, and chemicals of concern.
Results/Conclusions
Overall, cumulative stress is higher in nearshore than offshore waters and in the lower lakes (particularly Lakes Erie and Ontario). However, no location is without human influence from widespread stressors such as climate change, invasive species and nitrogen deposition. Locations providing ecosystem services are disproportionately proximate to areas of high stress. This effort, modeled upon recent global threat analyses for marine waters and rivers, will facilitate prioritizing restoration and conservation actions throughout the Great Lakes region.