The National Invasive Species Act (NISA) is a United States federal law intended to prevent invasive species from entering inland waters through ballast water carried by ships. NISA reauthorized and amended a previous measure, the Non-indigenous Aquatic Nuisance Prevention and Control Act of 1990 (NANPCA).
Organisms targeted by NISA are categorized as aquatic nuisance species, including in particular zebra mussels and Eurasian ruffe. To extend upon NANPCA, NISA authorizes regulation of ballast water, a key factor in the spread of aquatic invasive species; funding for prevention and control research; regional involvement with the Aquatic Nuisance Species Task Force; and education and technical assistance programs to promote compliance with the new regulations. NISA also includes specific actions for certain geographical locations, such as the Great Lakes, Chesapeake Bay, the Gulf of Mexico, and San Francisco Bay.
Environmental issue
NISA directly addresses problems associated with nonindigenous species, with special attention on aquatic nuisance species in the Great Lakes. In the proper conditions, nonindigenous species can out-compete indigenous species by dominating resources or spreading diseases or parasites. These disruptions can lead to a loss of biodiversity and as a result, ecosystems and economies are greatly affected. Below are a few descriptions of nonindigenous species that are mentioned in NISA.
Zebra mussels
In 1988 zebra mussels (Dreissena polymorpha) were found in Lake Erie, and soon after they spread to all the Great Lakes. Since then, zebra mussels can still be found in each of the Great Lakes, as well as throughout the major navigable rivers in the eastern part of the United States (including the Hudson, St. Lawrence, and Niagara Rivers). Recent reports have revealed that this species has dispersed as far as California.
A native of southern Russia, the zebra mussel most likely made its way to North America through the release of ballast water from cargo ships traveling from the Black Sea to the Great Lakes. After its introduction there, it was carried through the lakes and connected waterways via recreational and commercial traffic. A large part of the zebra mussel's ability to disperse has to do with its travel flexibility. In the larval stage, zebra mussels can float along passively. In the adult stage, zebra mussels can attach themselves to boats very well. Overland dispersal can be achieved, too, because these mussels can survive dry conditions for several days. This was most likely the way that they were introduced to California: agricultural inspection stations have reported finding mussels on the hulls or motor compartments of at least 19 trailered boats arriving into the state. In addition to being able to travel long distances during both immature and mature stages of life, zebra mussels can produce up to several hundred thousand eggs in a single season.
Zebra mussels are most disruptive in two ways. The first is that they can colonize and clog water supply pipes, thereby restricting water flow for systems used for cooling, fire-fighting, hydroelectricity, etc. Colonies can also be very dense: it was reported that at one power plant in Michigan, 700,000/m2 of zebra mussels were found in the pipes, the diameters of which were reduced by two-thirds. The United States Fish and Wildlife Service once estimated that zebra mussel infestations could cost $500 million per year due to increased costs for utility companies and industrial plants, as well as loss of income revenue for fishing and fishing-related businesses. The economic repercussions of this type of species invasion can be devastating.
The second issue with zebra mussel invasions is that they can deplete food sources in aquatic ecosystems. Zebra mussels are filter feeders, meaning that they consume microorganisms, and they do so at very fast rates. Microorganisms form the bottom of the food chain, and eliminating that food source can be dangerous to the survival of native species. The spread of the nonindigenous zebra mussels have greatly decreased the numbers of native mussels in Lake St. Clair and Lake Erie, which may be at risk for extinction.
Eurasian ruffe
The Eurasian Ruffe (Gymnocephalus cernuss) is another aquatic nuisance species that has spread to the Great Lakes, Wisconsin, and Michigan, after first being discovered in the St. Louis River Estuary of the Duluth-Superior Harbor in 1986. Originally from southern Europe, the ruffe is believed to have arrived in North America through the release of ballast water from foreign seas.