THE spread of invasive species carried across the world in the ballast tanks of ships is causing billions of pounds of damage each year, conservationists warned today.
Creatures such as the Chinese mitten crab have been able to establish themselves in new habitats after being transported from their natural homes in ballast water.
About 7,000 marine and coastal species travel across the world's oceans every day,
a report for wildlife conservation charity WWF said.
Some of them become invasive in new sites, breeding prolifically by "escaping" the predators or diseases which would normally keep their numbers under control, competing with local species, disrupting food chains or damaging habitats.
The report estimated that in the last five years, invasive species have cost marine and coastal activities including fisheries, aquaculture, industrial infrastructure and harbours some US$50 billion (£31bn) worldwide.
According to the study for WWF, last year 84 per cent of the world's marine regions had reported findings of invasive species, with shipping a major reason for their spread.
The conservation charity urged countries to adopt an international treaty which would bring in measures for ballast water – used to stabilise ships and ensure efficient fuel use – to tackle the problem.
Not enough countries have ratified the Ballast Water Convention, established in 2004, to bring it into force, with only one of the top shipping states – Liberia – doing so. As a result, the number of damaging species spreading into new areas is continuing to rise.
Invasive species include Chinese mitten crabs, which originate in the Far East but have spread to other parts of the world in the ballast of ships. The crab can burrow into and destroy fragile riverbanks, prey on other species and compete with native animals such as crayfish.
The North American comb jellyfish, which helped to virtually wipe out anchovy and sprat stocks in the Black Sea in the late 1980s, is now expanding into the Caspian Sea, the North Sea and the Baltic Sea.
The red mysid shrimp has spread from the Black and Caspian Seas into the North Sea, including Belgium, France, the UK and Ireland and across to the US – with fears its wide diet is likely to damage ecosystems.
The poisonous Indo-Pacific lionfish originally turned up in the Atlantic after being released from aquariums, but larvae and young could spread further in ballast water, which can also contain a number of bacteria and diseases including cholera.
Ahead of a meeting of the International Maritime Organisation in London this week, WWF called on nations under whose flags most ships operate to ratify the convention.
WWF's delegation head Dr Anita Makinen said: "The IMO Ballast Water Convention provides the set of agreed practices and standards for effective control of ballast water internationally, minimising the spread of marine invasive organisms while imposing minimal costs upon shipping and trade."
IN FOREIGN WATERSEXAMPLES of species with strong to moderate links to ballast water:
• North American comb jelly (pictured right) – increasingly found in north-west Europe and Norway, and Swedish coastal waters
• Australian spotted jellyfish – appeared in Texan waters in 2006 and threatens commercial shrimp and crab fisheries in Gulf of Mexico
• Conrad's false mussel – found in Finnish Baltic waters in 2004 and now increasing near cooling water outfalls of power plants
• North Asian amphipod – recorded for first time in Irish waters in 2006
• Gammarid amphipod (pictured right) – firmly established in northern Baltic and replacing native species
• Red mysid shrimp – native to the waters around the Black and Caspian Seas, it has reached Ireland and England
• Fish-hook water flea – clogs nets and fishing gear
• Asian shrimp – established in UK rivers and estuaries in the 1990s and has spread ever since
• Asian shore crab – discovered in Belgium and French coastal waters
