Environment Counts | 4 billion tons of ballast water discharged annually
Author: Rick Higgins – Published At: 2011-11-06 00:25 – (1715 Reads)
Ballast water is a critical factor in shipping. Failure to properly maintain ballast water can have catastrophic results. Ships have broken in two and/or capsized at sea when ballasting has been conducted improperly for the operational circumstances. Approximately 4,000 million tons of untreated ballast water (approximately 1.1 trillion US gallons) are discharged from ships every year. In USA alone more than 21 billion gallons of ballast water are discharged into U.S. waters from international ports every year. It is estimated that more than 10,000 marine species each day may be transported across the oceans in the ballast water of cargo ships and introduced into a non-native environment.
Ballast water is needed to provide stability and manoeuvrability during a voyage when ships are not carrying cargo, are not carrying heavy enough cargo, or require more stability due to rough seas.
Need forÂ ballast
The following sketch indicates a longitudinal cross section of a modern bulk carrier. The sections marked in grey are normally filled with water ballast when the holds are empty. As the cargo is delivered to the ship, the ship pumps out the water ballast into the receiving waters of the port. Larger or smaller bulk carriers simply have more orless hold spaces to carry extra cargo and of course more water ballast.
It is estimated that 3,400-4,000 million tons (other estimates range as high as 10,000 million tons)of untreated ballast water are discharged from ships every year in ports, as cargoes are loaded, and in coastal regions, as vessels deballast to reduce their draft and enter ports. Furthermore, it is estimated that more than 10,000 marine species each day may be transported across the oceans in the ballast water of cargo ships and introduced into a non-native environment. In USA alone more than 21 billion gallons of ballast water are discharged into U.S. waters from international ports every year.NOAA
Ships that take up ballast water in one area or sea, and then discharge it in another, can seriously disturb or alter the ecosystem by introducing “invasive” micro-organisms which establish themselves in the local environment. With the expansion of volume and density of international shipping the transfer of harmful aquatic species in ships’ ballast water tanks has become the most significant pathway of unintentional introductions of invasive alien species into marine ecosystems. As ballast water may be fresh, brackish or saline, the coastal environment, estuaries and navigable inland waters, are most at risk. The economic, social, recreational and ecological losses/costs of such invasive species are difficult to assess, as the losses of native species and environment restoration to pre-invasion quality are more difficult to determine and quantify.
Apart from affecting ecosystems and contributing to the extinction of native species, and therefore representing a significant threat to biodiversity, invasive alien species may also cause major socio-economic damage. Reported effects on human health deriving from alien invasive species include changes to the native food web and human consumption of contaminated seafood. Source
Two examples of invasive species transported by ships (in ballast and otherwise (eg the species attaches itself to the hull or anchor of a ship) are the comb jellyfish and the zebra mussel.
Comb jellyfish One of the worst cases of a single invasive species causing harm to an ecosystem can be attributed to a seemingly harmless jellyfish. Mnemiopsis leidyi, a species of comb jellyfish that inhabits estuaries from the United States to the ValdÃ©s peninsula in Argentina along the Atlantic coast, has caused notable damage in the Black Sea.
It was first introduced in 1982, and thought to have been transported to the Black Sea in a shipâ€™s ballast water. The population of the jellyfish shot up exponentially and, by 1988, it was wreaking havoc upon the local fishing industry. â€œThe anchovy catch fell from 204,000 tons in 1984 to 200 tons in 1993; sprat from 24,600 tons in 1984 to 12,000 tons in 1993; horse mackerel from 4,000 tons in 1984 to zero in 1993.â€http://www.pbs.org/wgbh/nova/nature/impact-invasive-species.html Now that the jellyfish have exhausted the zooplankton, including fish larvae, their numbers have fallen dramatically, yet they continue to maintain a stranglehold on the ecosystem. Recently the jellyfish have been discovered in the Caspian Sea. Invasive species can take over once occupied areas, facilitate the spread of new diseases, introduce new genetic material, alter landscapes and jeopardize the ability of native species to obtain food. http://en.wikipedia.org/wiki/Environmental_impact_of_shipping#Ballast_water
Zebra mussels are native to an area in Russia near the Caspian Sea. Canals built during the late 1700s and the 1800s allowed the mussels to spread throughout Europe. By the 1830s, the mussels had covered much of the continent and had invaded Britain. The introduction of zebra mussels into the Great Lakes appears to have occurred in the 1986, when a ship either discharged ballast water containing zebra mussel larvae or deposited live species into Lake St. Clair. The freshwater ballast would have been picked up in a European port or adult mussels may have been carried in a sheltered, moist environment, such as a sediment-encrusted anchor. The higher speed of modern shipping gives exotic species a better chance of surviving the trip across the Atlantic.
The rapid spread and abundance of the zebra mussel can be attributed to their reproductive cycles. A fully mature female mussel may produce up to one million eggs per season. Eggs are fertilized outside the mussel’s body and within a few days develop into free-swimming larvae drifting with the currents. It is estimated that only about 2 percent survive to adulthood. Mussel beds in some parts of Lake Erie now contain more than 30,000 and sometimes up to 70,000-mussels per square meter. Adult mussels are very hardy and can survive out of water for about 10 days for adults.
Zebra mussels disrupt the aquatic food chain. They eat mostly algae filtering more than one litre of water per day, removing significant amounts of phytoplankton from the water.
Zebra mussels remove the food source for zooplankton that are food for juvenile fish. These fish support sport and commercial fisheries. Pollutants accumulate in mussel tissue and the human health implications for consumers of the fish or waterfowl are not yet understood. As zebra mussels spread, biologists are concerned that populations of native mussels will decline, and some of the rarer species may be completely eliminated.
Zebra mussels foul water intakes such as those used for power generation and water treatment plants. Since 1989, some of these plants have reported high costs associated with the impact of zebra mussel colonisation. The have reported significant reductions in pumping capabilities and occasional shutdowns for cleaning and removal of mussels. Recreation industries along the lake shores have also been affected by zebra mussels settling on breakwaters, boat bottoms, and outboard engines. Numerous reports of engines overheating due to colonies of zebra mussels clogging cooling water inlets have been received. The control of zebra mussels is not yet practicable. Neither the European community nor the Great Lakes Region have been able to develop a treatment for control that is not deadly to other aquatic life forms. http://www.pkharbour.org/Ballast%20Water%20Issues.htm#Case%20History
Other invasive species Of the hundreds of organisms carried in ballast water that cause problematic ecological effects outside of their natural range. The International Maritime Organization provides the following list of the ten most unwanted species.
- 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
A table summarising key environmental impacts of each of these species is included in the following IMO report.
IMO Ballast Water ManagementÂ Convention
In September 1995, the International Maritime Organization (IMO) identified invasive species as a major issue confronting the international maritime community. In February 2004, the IMO adopted the â€œInternational Convention for the Control and Management of Shipsâ€™ Ballast Water and Sedimentsâ€ (Convention), which established ballast water management procedures and included an international standard for ballast water discharge. There are 15 implementing guidelines within the Convention. The last two were finalized in 2008 at the 58th session of the Marine Environment Protection Committee of IMO. The Convention will enter into force one year after ratification by 30 countries representing not less than 35 percent of the grass tonnage of the worldâ€™s merchant shipping. As of October 2009, Eighteen countries, representing 15.36 percent of the gross tonnage, had signed the Convention. (To date the U.S. has not ratified the BWM Convention.)
In addition to the BMW Convention a consortium of international organisations (GEF/UNDP/IMO) has established the GloBallast Partnerships programme http://globallast.imo.org/ to assist developing countries to;
- reduce the transfer of harmful aquatic organisms and pathogens in ships’ ballast water,
- implement the IMO ballast water Guidelines, and
- prepare for the new IMO ballast water Convention.