Examples of Invaders
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Some aquatic invaders that have been spread by ballast water
Like many parts of the world, Puget Sound, the Columbia River and the Washington Coast are now home to aquatic invasive species (also known as aquatic nuisance species). Many of these may have been introduced by ballast water. Luckily, no invasions in our state have been catastrophic yet, but other areas have been devastated.
The Washington Department of Fish and Wildlife houses Washington state’s Aquatic Nuisance Species Program.
Plankton
Most of the aquatic invasive species introduced into Washington waters through ballast water have been plankton. These small aquatic plants or animals form the base of the aquatic food web. Once established in a new place, they are virtually impossible to remove. Introductions of invasive plankton can upset the balance in the local food web or create water quality problems that kill off native plants and animals.
The Washington Department of Fish and Wildlife is collecting samples of ballast water and researchers at UW are analyzing them in hopes of assessing the risk that ballast water poses to the wildlife that live in Washington waters.
The European Green Crab
The European green crab (Carcinus maenas) was most likely introduced to the west coast through ballast water and migrated north to Washington in ocean currents.
Green crabs eat molluscs, crustaceans, polychaetes (marine worms) and green algae. They have been linked to the decline in the scallop fishery in the northeast US and are a concern for the Dungeness crab fishery on the west coast of the US.
Mitten crabs
Mitten crabs are the only freshwater crabs in North America. While they spend most of their lives in freshwater, they migrate to salt water to reproduce, so can be picked up in harbor ballast water. The Chinese mitten crab (Eriocheir sinensis) was first discovered in San Francisco Bay in 1992 and quickly spread to the Sacramento and San Joaquin rivers.
Mitten crabs burrow for protection, weakening levees and aggravating bank erosion. They eat the eggs of salmon, trout and sturgeon. They may pose a serious threat to ecosystems and fisheries along the West Coast.
When migrating, the crabs clog fish screens and water intakes.
A single male Japanese mitten crab (Eriocheir japonica) was found in the Columbia River in 1997. Although there have been other reports of sightings, mostly by fishermen, no more have been captured.
The risk of more introductions through ballast water is considered high because mitten crabs are now established in three global transportation centers: China, Europe and San Francisco.
Invasive Tunicate (Sea Squirt)
Tunicates (also known as sea squirts) are siphon-feeding marine animals—they suck water through their intestinal systems to feed. They have no known predators and can quickly blanket the hull of boats, pilings and other hard surfaces, out-competing or suffocating other sea life, including clams, mussels and oysters.
Three invasive tunicate species have been found in Washington’s waters, two are natives of Asia, the clubbed tunicate (Styela clava), and the solitary sea squirt (Ciona savignyi); the third is a native of Europe, the colonial sea squirt (Didemnum lahillei).
The colonial sea squirt was found growing on the hull of a sunken boat near Edmonds in 2004. Since then, at least a dozen other invasive tunicate colonies have spread throughout the sound, in Hood Canal, Birch Bay, Totten Inlet, Des Moines, and Elliot Bay.
As they continue to spread, they pose a serious threat to our multi-million dollar shellfish industry.
The Department of Fish and Wildlife is developing a management plan for the control and possible eradication of invasive tunicates. A comprehensive survey of Puget Sound marinas was conducted in the summer of 2007 to determine the extent of the invasion and to plan control and, eradication procedures for the fall and the spring of 2008.
Zebra and Quagga Mussel
Zebra mussels (Dreissena polymorpha) and Quagga mussels (Dreissena bugensis) are native to the Caspian Sea. They were introduced into the Great Lakes in the mid-1980’s, in ballast water, and have since spread to more than twenty states and two Canadian provinces.
As they can live outside the water for up to a month, they are easily transported by boats and other water recreational vehicles. Quagga mussels were recently found in Lake Mead, near Boulder City, Nevada. They have been found on boats in Washington State being transported from Lake Mead—fortunately, before those boats were launched into state waters.
The zebra mussel costs an estimated $5 billion per year to control. They grow in dense, colonies of up to 700,000 organisms per square meter. These colonies can clog water intake pipes that serve water filtration and electric generating plants. In some cases, pipes are effectively reduced to two thirds their actual size.
The zebra mussel has also spread throughout Europe, where facilities in infested waters simply install two sets of pipes, so one is always in operation when the other set is being cleaned.
For more information on Aquatic Invasive Species, please visit: The USGS Nonindigenous Aquatic Species Repository
The Washington Department of Fish and Wildlife houses Washington state’s Aquatic Nuisance Species Program.
Plankton
Most of the aquatic invasive species introduced into Washington waters through ballast water have been plankton. These small aquatic plants or animals form the base of the aquatic food web. Once established in a new place, they are virtually impossible to remove. Introductions of invasive plankton can upset the balance in the local food web or create water quality problems that kill off native plants and animals.
The Washington Department of Fish and Wildlife is collecting samples of ballast water and researchers at UW are analyzing them in hopes of assessing the risk that ballast water poses to the wildlife that live in Washington waters.
The European Green Crab
The European green crab (Carcinus maenas) was most likely introduced to the west coast through ballast water and migrated north to Washington in ocean currents.
Green crabs eat molluscs, crustaceans, polychaetes (marine worms) and green algae. They have been linked to the decline in the scallop fishery in the northeast US and are a concern for the Dungeness crab fishery on the west coast of the US.
Mitten crabs
Mitten crabs are the only freshwater crabs in North America. While they spend most of their lives in freshwater, they migrate to salt water to reproduce, so can be picked up in harbor ballast water. The Chinese mitten crab (Eriocheir sinensis) was first discovered in San Francisco Bay in 1992 and quickly spread to the Sacramento and San Joaquin rivers.
Mitten crabs burrow for protection, weakening levees and aggravating bank erosion. They eat the eggs of salmon, trout and sturgeon. They may pose a serious threat to ecosystems and fisheries along the West Coast.
When migrating, the crabs clog fish screens and water intakes.
A single male Japanese mitten crab (Eriocheir japonica) was found in the Columbia River in 1997. Although there have been other reports of sightings, mostly by fishermen, no more have been captured.
The risk of more introductions through ballast water is considered high because mitten crabs are now established in three global transportation centers: China, Europe and San Francisco.
Invasive Tunicate (Sea Squirt)
Tunicates (also known as sea squirts) are siphon-feeding marine animals—they suck water through their intestinal systems to feed. They have no known predators and can quickly blanket the hull of boats, pilings and other hard surfaces, out-competing or suffocating other sea life, including clams, mussels and oysters.
Three invasive tunicate species have been found in Washington’s waters, two are natives of Asia, the clubbed tunicate (Styela clava), and the solitary sea squirt (Ciona savignyi); the third is a native of Europe, the colonial sea squirt (Didemnum lahillei).
The colonial sea squirt was found growing on the hull of a sunken boat near Edmonds in 2004. Since then, at least a dozen other invasive tunicate colonies have spread throughout the sound, in Hood Canal, Birch Bay, Totten Inlet, Des Moines, and Elliot Bay.
As they continue to spread, they pose a serious threat to our multi-million dollar shellfish industry.
The Department of Fish and Wildlife is developing a management plan for the control and possible eradication of invasive tunicates. A comprehensive survey of Puget Sound marinas was conducted in the summer of 2007 to determine the extent of the invasion and to plan control and, eradication procedures for the fall and the spring of 2008.
Zebra and Quagga Mussel
Zebra mussels (Dreissena polymorpha) and Quagga mussels (Dreissena bugensis) are native to the Caspian Sea. They were introduced into the Great Lakes in the mid-1980’s, in ballast water, and have since spread to more than twenty states and two Canadian provinces.
As they can live outside the water for up to a month, they are easily transported by boats and other water recreational vehicles. Quagga mussels were recently found in Lake Mead, near Boulder City, Nevada. They have been found on boats in Washington State being transported from Lake Mead—fortunately, before those boats were launched into state waters.
The zebra mussel costs an estimated $5 billion per year to control. They grow in dense, colonies of up to 700,000 organisms per square meter. These colonies can clog water intake pipes that serve water filtration and electric generating plants. In some cases, pipes are effectively reduced to two thirds their actual size.
The zebra mussel has also spread throughout Europe, where facilities in infested waters simply install two sets of pipes, so one is always in operation when the other set is being cleaned.
For more information on Aquatic Invasive Species, please visit: The USGS Nonindigenous Aquatic Species Repository