Freshwater ecosystems are threatened by a host of environmental stressors from human activities. Among the most insidious and impactful of these is invasion by non-native species.
Over the past two centuries, established populations of nearly 190 non-native species of invertebrates, fishes, plants and microbes have been discovered in the Great Lakes basin. They were introduced through several sources and pathways including canals, pet release, bait bucket dumping, aquaculture escapes and — most notably — ballast water discharge from transoceanic ships.
