A small freshwater mollusk called the zebra mussel (Dreissena polymorpha) has invaded fresh waters across Canada and North America. Boaters are carelessly spreading this destructive pest in bilges and bait wells of trailered boats. Boating in Canada has been complicated, since even small boats without special bottom paint will grow these mollusks within a few months. They have spread to the Great Lakes, the St. Lawrence River and many freshwater lakes and canals, changing the very face of our aquatic ecology.
They first appeared in Canada in 1988 in Lake St. Clair, a small lake connecting Lake Huron and Lake Erie in the Great Lakes. It is assumed the zebra mussels were discharged in the ballast water from a ship from a freshwater European port. (About 160 invasive species have been imported by cargo ships, most causing environmental and economic problems.)
Zebra mussels can survive up to 5 days out of water. They live only in fresh water and attach themselves to any underwater surface. They are about the size of a fingernail but can grow up to 5 cm. long. They need flowing fresh water to thrive so are not as much of a problem in quiet lakes and bays. A female is able to lay up to one million eggs during a single breeding season! The only natural control is a species of diving duck.
Zebra mussels spread downstream during their free-swimming larval stage. Dispersal upstream and into inland rivers and lakes occurs with human activity: larvae are dumped from livewells and older ones attach themselves to boats. Trailered boats are to blame for spreading the mussels throughout the fresh water lakes and rivers in the Great Lakes basin once they were introduced there (believed around 1988).
Cooling water left in an engine cooling system when a boat is not in use does not seem to support their growth. They do not attach themselves to hulls protected with anti fouling paint. Colonies of mussels can clog water intakes on boats in use however.
Zebra mussels often fasten themselves in clusters to the shells of native mussels, preventing them from breathing, feeding and moving, so they die. Clams have virtually disappeared from western Lake Erie! Colonies of zebra mussels in Lake Erie have reached astounding densities of 70,000 per square meter according to estimates. Lake Erie is estimated to be filtered completely each week. Because of this, zebra mussels have high concentrations of toxins -- which are passed on to any waterfowl that feed on them. Water clarity has increased sixfold and light reaching the bottom has caused increases in bottom plants.
Zebra mussels clog water intake pipes and turn docks and pilings into surfaces that can tear your skin off. Clogged water supply pipes have cost many millions of dollars to repair.
They filter algae from the water, turning it clear. Scuba diving in the Great Lakes area has become a growing sport because you can now see in the water. Unfortunately, the absence of microscopic aquatic plant and animal life will cause many species to disappear as the ecosystem changes radically.
"Clean, Drain, Dry" campaign is to educate recreational boaters to help stop the spread of harmful aquatic invasive species.
Hot water will kill zebra mussels (only useful for a very small bilge!). Chlorine will also kill them, but is very toxic to marine life. Potassium, bromine, ozone and ultraviolet light are less toxic alternais are difficult to apply under water. A novel experiment was reported at the Sixth International Zebra Mussel and other Aquatic Nuisance Species Conference in March 1996,
Researchers at Purdue University have discovered that radio waves will kill zebra mussels. Their experiments exposed them to low-energy radio waves in fish tanks, which killed the zebra mussels in 40 days. It appeared the radio frequency caused them to lose the calcium they need to survive. Other organisms in the tanks, such as other freshwater mussels and crabs were significantly less harmed and fish were not harmed at all. This is not very practical for a lake but could be used around water intakes.
"...included "Penaten" cream, a product normally used by parents of newborns. This product, which has a significant zinc component, not only reduced mussel settlement but also prevented diaper rash on all of the boats tested!"
Some say 'get out the butter and garlic!' as there must be some other silver lining in this pest!
Source: Great Lakes United, www.glu.org
Quagga mussels are closely related to zebra mussels. The nonnative organisms have infested the Colorado River system and could easily spread throughout the Pacific Northwest fresh-water lakes and rivers on trailer boats.
Quagga mussels are very small but breed quickly and adhere to practically any surface. They threaten native fish by consuming food and smothering other species. As with zebra mussels, they can clog pipes and water intakes, and cause damage to hydroelectric dams and irrigation systems. The mussels are hardy, capable of surviving out of water for a month and tolerant of a wide range of temperatures and water conditions.
The organisms spread by riding on boats and trailers that have been in an infested lake or river. Pressure-washing boats and trailers with scalding water destroys the mussels.
Native to the Caspian Sea, zebra and quagga mussels entered the Great Lakes in the mid-1980s in ship ballast water. As of 2009, they have spread to 20 states and two Canadian provinces. Boat owners need to take responsibility for their vessels to keep these invasive species from spreading to other waterways.
Like the majority of the 185 known invasive species in the Great Lakes, the round goby was transported in the ballast water of ocean-going ships in the St. Lawrence Seaway and the Great Lakes. It was first seen in the St. Clair River between Lake Huron and Lake Erie in 1990.
Today millions of round gobies are thriving in the Great Lakes. Their ecological impact has been complicated, sometimes harmful but also beneficial in some cases. Round gobies are among the few predators of zebra mussels (above) for example. They provide an abundant food source for valuable sport fish such as smallmouth bass and non-native, stocked species like brown trout. Cormorants, migratory water birds with massive populations across the Great Lakes, love round gobies so much that they have spared sport fish to eat them.
But there is a down side. Gobies eat the eggs and larva of other fish. They also spread deadly botulism, picking it up from mussels and passing it on to ducks that eat them. The gobies also defend their spawning habitat so aggressively that native fish can?t reproduce. If a smallmouth leaves its nest, round gobies will devour its eggs. But if the eggs hatch, the young bass will begin a lifetime of eating gobies. [More...]
Canadian and United States agencies, the International Joint Commission, and the Great Lakes Fishery Commission have joined together to stop the spread of Asian Carp north to the Great Lakes using an electrical barrier on the Chicago Canal. The Canal connects the Mississippi River to the Des Plaines River approximately 50 miles from Lake Michigan. (By the time you read this, they may have reached the Great Lakes.)
Asian Carp have rapidly advanced up the Mississippi River toward the Great Lakes. They threaten the biological integrity of any waters they enter, which in turn threatens food and water resources, recreation and jobs. Fish markets in Canadian cities sell live Asian Carp. Without a law to stop live fish from entering Canada, they will eventually populate the Great Lakes.
Asian Carp are a significant threat to the Great Lakes because of their size, reproduction, and ability to consume large amounts of food. Asian Carp can grow to 100 pounds and up to four feet long. They are well-suited to the climate of the Great Lakes region, which is similar to their native Eastern Hemisphere habitats. It is expected they would compete for food with the valuable sport and commercial fish. If they entered the system, they could become a dominant species in the Great Lakes.
Two species of Asian Carp - the silver and the bighead carps - escaped into the Mississippi River in the 1980s and spread during floods in the early 1990s. They are now the main fish species in some parts of the Mississippi, out-competing native fish, and causing severe hardship to the people who fish the river.
The specter of large, prolific Asian Carp in the Great Lakes has motivated a coalition of U.S. government and the IJC to act swiftly, due to the environmental and economic havoc caused in the Great Lakes by previous aquatic invasions of zebra mussels, sea lamprey, and round gobies. The latest threat from Asian Carp underscores the serious problems posed by invasive species and the urgent need to prevent further introductions. The Great Lakes simply cannot afford another aquatic invasion."
"Fortunately, we do have a first line of defense against the Asian Carp invaders," said Brigadier General Steven R. Hawkins, commander of the Great Lakes and Ohio River Division, U.S. Army Corps of Engineers. "In April, 2002, the U.S. Army Corps of Engineers completed construction of an electrical fish barrier to study the effectiveness of preventing migration of species between the Mississippi and Great Lakes watersheds. The barrier uses electricity to repel fish and hopefully will prevent fish passage. Because the barrier relies on electricity, we were concerned that a simple power outage could allow Asian Carp to sneak past. The emergency funds from the federal and binational partners have allowed the Corps to purchase the backup generator we need to ensure an unbroken supply of power to the barrier." To date, silver and bighead carp have not been sighted upstream of this barrier.
Agencies and stakeholders will continue to work to prevent the migration of Asian Carp and other invasive species through the Chicago Sanitary and Ship Canal. Partners in this effort include: Chicago Mayor Richard Daley, Commonwealth Edison, the Council of Great Lakes Governors, the Dispersal Barrier Advisory Panel, the Great Lakes Fishery Commission, the Great Lakes Sportfishing Council, the Illinois Department of Natural Resources, the International Joint Commission, the Metropolitan Water Reclamation District of Greater Chicago, Midwest Generation, the Mississippi Interstate Cooperative Resource Association, the New York Department of Environmental Conservation, the U.S. Army Corps of Engineers, the U.S. Environmental Protection Agency, the U.S. Fish and Wildlife Service, Wisconsin Sea Grant, and other state, nongovernmental, and academic partners.
(Information supplied by the International Joint Commission)
Great Lakes Fishery Commission: Marc Gaden 734-662-3209 x. 14
International Joint Commission: Frank Bevacqua 202-736-9024
U.S. Army Corps of Engineers: Lynne Whelan 312-353-6400 x1300
U.S. Department of State: Karla Heidelberg 202-647-0241
U.S. Environmental Protection Agency: Phillippa Cannon 312-353-6218
There are too many invasive species to list here. (See links below)
One of the few places where the invasive plant, hydrilla, was stopped from spreading is Lake Manitou on Manitoulin Island, Ontario, between Lake Huron and North Channel. It was probably brought in on a trailered boat. The lake was closed for three years, the waters treated, and the invasive plant was stopped. It would have been deadly if it had spread to the Great Lakes.