About 5,000 to 7,000 species are currently in motion around the world in the ballast water of cargo ships. For the last lecture of this spring’s Oceans Symposium, James T. Carlton, director of the Williams Mystic Program, described the effects of these invasive species on the Atlantic Coast, and throughout the world.
Ballast water is water used for weight on cargo ships. Through a piping system, ships pick up water within the bay before departure, and empty it into foreign waters throughout their journey. These containers of ballast water “are not abiotic environments;” they hold zooplankton, crabs, snails, shrimps, and even fish. Species native to one place are being shipped across the world in large aquatic tanks. 90% of all world goods are carried by cargo ships that carry these aquatic tanks: “the bottom line here is that human activity is not simply speeding up changes that would happen anyway.” Though the influx of some invasive species is normal, this high rate of invasion all over the world is far from “natural.”
The Japanese shore crab, first found in New Jersey in the 1990s. has become by far the most common carbon the east Coast.
In the 2000s, a seasquirt arrived in the Gulf of St. Lawernece, Canada, disrupting commercial mussel farms.
In 2001, Hurrican Bill washed ashore a huge amount of seaweed. 10-20% of it was an invasive species.
In the 1990s, the Pacific Lionfish found its way to Florida. It is now one of the most common fish in the Gulf.
On a sea wall in San Francisco bay, you might see Atlantic barnacles, Australian tubeworms, and New England mussels: “an accidental zoo.”
In 1988, the Zebra Mussel arrived in Lake St. Clair, and they have since colonized the Great Lakes.
After years of advocacy for a vector management policy, a final rule was put in place on March 23rd of this year. On page 17254 of the federal register, it says that every arriving ship must follow specific discharge standards. “Does this mean anything?” Carlton knew we were asking: “It’s complicated.”
“We exist in an era when attention to all these drivers of change have never been better,” Carlton exclaimed. Carlton’s hope that in the future there will be fewer invasions stems from the fact that “we have people whose entire careers are based on addressing and ameliorating this situation.”
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