Ballast water is an amazing way to carry invasive species from one part of the world to another. Think about it: these gigantic ships suck up tens of thousands of tons of water and deliver it sealed and ready to go all around the world. They do nothing at all to kill off bacteria or critters that get scooped up.
And this is why the lakes of Michigan are slowly becoming hostile to humans with their zebra mussels. And why other waterways are dead now.
Ships must kill off the beasties in the ballast water - opinion - 01 April 2013 - New Scientist
THEY called it the blob that ate the Black Sea. Thirty years ago, a ship from North America sailed up the Bosphorus and dumped ballast water containing comb jellyfish from back home. The invader – Mnemiopsis leidyi – went crazy, gobbling up plankton and triggering a catastrophic decline in marine life, including commercial fisheries. At one point its biomass reached a billion tonnes, 10 times the world's annual fish landings.
Around a decade later an unknown ship, probably from the Bay of Bengal, discharged ballast water into the coastal waters of Peru, releasing a strain of cholera that contaminated shellfish. People ate the shellfish and the disease spread, killing 12,000 across Latin America.
Right now, the same thing, or something worse, could be happening almost anywhere. A United Nations treaty agreed in 2004 requiring ships to install kit to kill off biological stowaways in their ballast water has still not been ratified by enough nations to come into force. Its day may come when the environmental protection committee of the UN's International Maritime Organization (IMO) meets in London in May. We can hope so, but that has been said many times before.
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Ecologists say that alien species are the second biggest threat to the planet's biodiversity after habitat destruction. Marine species are among the most enthusiastic invaders, and the global transport of ballast water is the single biggest cause of their spread. That's how the European zebra mussel got into North America's Great Lakes, where billions of dollars were spent to keep it from blocking irrigation channels and water pipes. That is how the dinoflagellates that cause toxic "red tides" spread round the globe, how Chinese mitten crabs reached Europe, how Asian kelp made it to southern Australia, and how Mediterranean mussels came to carpet the coast of South Africa.
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