Ballast water discharge and the environment
Cruise ships, large tankers, and bulk cargo carriers use a huge amount of ballast water, which is often taken on in the coastal waters in one region after ships discharge wastewater or unload cargo, and discharged at the next port of call, wherever more cargo is loaded. Ballast water discharge typically contains a variety of biological materials, including plants, animals, viruses, and bacteria. These materials often include non-native, nuisance, exotic species that can cause extensive ecological and economic damage to aquatic ecosystems.
There are hundreds of organisms carried in ballast water that cause problematic ecological effects outside of their natural range. The International Maritime Organization list the ten most unwanted species as:
- Cholera Vibrio cholerae (various strains)
- Cladoceran Water Flea Cercopagis pengoi
- Mitten Crab Eriocheir sinensis
- Toxic algae (red/brown/green tides) (various species)
- Round Goby Neogobius melanostomus
- North American Comb Jelly Mnemiopsis leidyi
- North Pacific Seastar Asterias amurensis
- Zebra Mussel Dreissena polymorpha
- Asian Kelp Undaria pinnatifida
- European Green Crab Carcinus maenas
Ballast water issues by country
The ballast tanks in New Zealand carry animals and plants that kill ecosystems. Ballast tanks are only used in cargo ships there. Ballast water is controlled under the Biosecurity Act 1993 in New Zealand.
The zebra mussel, native to the Caspian and Black Seas arrived in Lake St. Clair in the ballast water of a transatlantic freighter in 1988 and within 10 years spread to all of the five neighbouring Great Lakes. The economic cost of this introduction has been estimated by the U.S. Fish and Wildlife Service at about $5 billion.
Ballast water discharges are believed to be the leading source of invasive species in U.S. marine waters, thus posing public health and environmental risks, as well as significant economic cost to industries such as water and power utilities, commercial and recreational fisheries, agriculture, and tourism. Studies suggest that the economic cost just from introduction of pest mollusks (zebra mussels, the Asian clam, and others) to U.S. aquatic ecosystems is more than $6 billion per year.
Congress passed the National Invasive Species Act in 1996 in order to regulate ballast water discharges. The law expired in 2002. The Environmental Protection Agency and Coast Guard both have some ongoing responsibilities for regulating pollution from ships, but ballast water discharges are not currently subject to permit requirements under the Clean Water Act.
- "International Convention for the Control and Management of Ships' Ballast Water and Sediments". International Maritime Organization. Retrieved 2009-07-11.[dead link]
- Living Beyond Our Means: Millennium Ecosystem Assessment, 2005. Statement from the Board
- Statement of Catherine Hazlewood, The Ocean Conservancy, “Ballast Water Management: New International Standards and NISA Reauthorization,” Hearing, House Transportation and Infrastructure Subcommittee on Water Resources and Environment, 108th Cong., 2nd sess., March 25, 2004.
- David Pimentel, Lori Lach, Rodolfo Zuniga, and Doug Morrison, “Environmental and Economic Costs Associated with Non-indigenous Species in the United States,” presented at AAAS Conference, Anaheim, CA, January 24, 1999.
- Pub. L. 104-332. October 26, 1996.
- GloBallast partnership (IMO)
- International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM) (IMO)
- INTERNATIONAL CONVENTION FOR THE CONTROL AND MANAGEMENT OF SHIPS' BALLAST WATER AND SEDIMENTS, 2004
- GloBallast partnership (IMO)
- Ballast Water Management to Combat Invasive Species Congressional Research Service