Aquatic Invaders and Our Coastlines
How they Travel
AIS species can arrive through many different pathways, but most AIS arrived as a direct result of human activity. Common pathways of introduction include:
- Ship (Ballast) water operations
- Organisms attaching to ship hulls
- Release of fishing bait
- Intentional release of unwanted pets
- Release of classroom and laboratory animals
- Accidental release within the plant and animal trade
- Transported on watercraft and recreational equipment
- Escape from aquaculture facilities, nurseries, or water gardens
- Intentionally stocked as food or recreational sources
- Released as biological control of existing an existing invader
- Introduced for habitat restoration or erosion control efforts
February 24, 2012
Aquatic invasive species are marine or freshwater organisms that have found their way to habitats where they are not native, and negatively affect ecosystems. They have a significant effect on our coastlines, and many people are dedicated to finding new ways of preventing and controlling these invasions in our waters. February 27- March 3, National Invasive Species Awareness Week includes five days of activities, briefings, workshops and events focused on finding solutions to prevent, detect, monitor, and control invaders. Many state, local, national and international partners will be attending the event. Peg Brady, Strategic Planning Lead & Liaison to the National Invasive Species Council & Aquatic Nuisance Species Task Force tells us more about these species and why we need to be aware of them.
What are some examples of aquatic invasive species (AIS)?
Two classic examples are the quagga and zebra mussels and the lionfish. Quagga and zebra mussels are from Eurasia—now they’re found across the Great Lakes region and invading the waters of the western U.S. The lionfish, originally from the Indo-Pacific, is widely found in the coastal waters of southeast U.S. and Caribbean and many aquariums and pet stores across the country. The National Aquarium and others display lionfish to raise awareness about displaced species.
Where do they commonly exist?
Typically invaders take hold in healthy or unhealthy habitats, where they can out compete native creatures that are struggling to survive. Successful invaders reproduce quickly and abundantly, and can survive in a wide range of temperatures, salinities, and oxygen levels.
How do aquatic invasive species find habitats where they don’t belong?
There are many pathways. However, two examples are through shipping and recreational activities. As cargo is unloaded from a ship or fuel is used, the ship becomes lighter and floats higher in the water. To stabilize the ship, water must be taken on board as ballast. As a result living organisms including animals, plants and pathogens are transported in the ballast water from port to port. Each year about 21 billion gallons of ballast water is introduced to the U.S—that’s about 40,000 gallons per minute! An estimated 10,000 marine species travel around the world in ballast water annually. Recreational fishermen who may not clean their boats properly and the bait trade transport organisms that may hitchhike from place to place. The public needs to be aware of these pathways and help prevent new invasions.
Why should we care about aquatic invaders?
They impact our ecosystems and the diversity of life on our planet. The quagga and zebra mussels have had a domino effect on the Great Lakes region—the invaders take in so much plankton that it robs the native organisms of food, which also means more sunlight penetration to deeper waters thus creating unhealthy amounts of algal growth. Lionfish live alongside economically important snapper and grouper, and can hamper stock rebuilding efforts and coral reef conservation. Aquatic invaders take a toll on the economy; experts estimate that control efforts exceed $138 billion a year.
How are these species discovered?
Often it’s through divers or people who explore the coast. They have a keen eye because they know the environment well. They might take what they find to a local aquarium, or they will look it up in the U.S. Non-Indigenous Aquatic Species Database, which lets people report findings and receive alerts on other findings.
How do we control invasive species?
Controlling invasive species requires knowledge regarding how the organisms were introduced. Armed with that information we try to prevent new invasions into our waters before they begin. For example, international efforts are underway to clean ballast water and reduce biofouling—organisms attached and carried by the ship’s hull. When we’re unsuccessful and an invader becomes established, efforts are undertaken to remove the invaders. To control the lionfish population, divers spear fish because it is difficult to capture them through traps or fishing lines.
What should everyone know about invasive species, that they might not know?
Invasive species can be just as harmful as a chemical spill to the marine environment. In fact, invasive species are considered biological pollution. That's why we need new ways to protect marine ecosystems and reduce the threat of invaders. More effort is needed to educate the public about invasive organisms, their pathways, and strategies to prevent their introductions.
What can be done?
Once they take hold, aquatic invasive species (AIS) are very expensive to control, which means preventing them in the first place is the most cost effective and environmentally sensitive tool. But preventing new invasions requires creative approaches to education and outreach, screening and injurious wildlife prohibitions, and rapid response techniques.
Even the best prevention efforts will not stop all invasions. When a new invasion occurs, the best strategy is early detection and rapid response. This includes actively monitoring habitats in order to discover newly established species, reporting sightings of previously unknown species in an area, and working quickly and diligently to keep the species from becoming established and spreading. These efforts increase the likelihood that invasions will be addressed successfully while populations are still localized and population levels are not beyond that which can be contained and eradicated.
Control and management is necessary in areas where AIS are already established to prevent their further spread and lessen their impacts on native ecosystems. Research is often needed before appropriate control and management measures can be identified.