Great Lakes Aquatic Invasive Species

Agency: Environmental Quality

Nonindigenous species, also commonly referred to as nuisance, non-native, exotic, invasive and alien species, are species that did not originate in the Great Lakes ecosystem and have been introduced either intentionally or accidentally. Over 160 species have been introduced into the Great Lakes basin since the 1800s.  More than 1/3 of the species have been introduced into the Great Lakes in the last half of the 20^th century coinciding with the expansion of the St. Lawrence Seaway in 1959, which allowed greater transoceanic shipping traffic.  Species, such as the zebra mussel, ruffe, goby, and others also considered aquatic nuisance species (ANS), threaten the diversity or abundance of native species and the ecological stability of infested waters, or commercial, agricultural, aquacultural or recreational activity dependent upon the lake. The four primary vectors of entry include ballast water from ocean-going ships, unintentional releases, multiple sources and unknown. 

The introduction of nonindigenous species into an established ecosystem can alter or disrupt existing relationships and ecological processes. This disruption has caused significant changes to the ecosystem, such as alterations of food webs, nutrient dynamics, reproduction, sustainability, and biodiversity. Without co-evolved parasites and predators, some nonindigenous aquatic species are a nuisance because they out-compete and even displace native populations. Organisms invading the Great Lakes can also threaten public health through disease, concentration of pollutants, contamination of drinking water, and other harmful human health effects.  Exotic species can also have economic impacts.  Local communities dependent upon water from the Great Lakes or tourism as a major portion of their economy can be severely impacted by the introduction of species.  Additionally, the quality of life of the citizens of these communities can be impacted by the introduction of these organisms.  The zebra mussel, for example, colonizes the intake/discharge pipes of hundreds of facilities that use raw water from the Great Lakes, incurring extensive monitoring and control costs.  Recent studies estimate that over the next ten years, roughly $3 million will be spent on monitoring and control costs for the zebra mussel. This estimate excludes impacts on Great Lakes fisheries.  Research has yet to discover an effective control for most of these species.  This biological form of pollution has altered the ecosystem more than pollution by chemical contaminants ever has.