Saltwater ships pose hazard to Great Lakes
By Eric Sharp
Detroit Free Press
Posted on the Holland Sentinel on December 20, 2007
GRAYLING | When it comes to protecting the Great Lakes from exotic species imported by saltwater ships there's bad news, and there's worse news.
The bad news is that an investigation of the ballast tanks of 41 ships entering the lakes found 93 different kinds of animals, 13 of which haven't been seen in the Great Lakes before.
The worse news is that an examination of the fouling on the outside of a ship has found dozens more potential exotic invaders, many of them freshwater species from all around the world.
The studies by David Lodge of the University of Notre Dame and John Drake of the University of Georgia are among the first to both quantify the numbers of potential invasives and figure out the species or at least the genus of the exotics to get a better handle on which ones might make it in the lakes.
The ship they looked at when it went into dry dock in Lake Ontario was badly fouled after a long voyage that took it from Algeria in the Mediterranean Sea to Chile on the west the coast of South America and then through the Caribbean Sea and up the east coast of the United States to the St. Lawrence River.
Lodge and Drake scraped the growth from a 3-by-3 foot square from the ship's hull.
"Previous studies focused on ballast water and sediments (in the ballast tanks)," Lodge said. "We think there may be as great or an even greater risk from the (creatures) living on the outsides of the ships."
Not that the insides of the vessels were biologically clean. Sampling water from 62 ballast tanks and sediments from 41 others, Lodge and Drake found 641 living organisms.
Lodge said they missed stuff too small to be sampled -- eggs and spores that still might be able to germinate in the Great lakes.
The sediments are significant because a majority of the ships coming into the lakes from salt water declare that they have no ballast on board and are therefore exempt from inspection. But their tanks do hold huge amounts of sediments that are alive with creatures from all over the world.
And when those ships take on cargo and adjust their ballast in the lakes, the creatures in those sediments can get into our fresh water.
Even worse, the marine plants and other organisms that live on the outside of the hulls provide a refuge for all kinds of small creatures that could be disastrous to the ecology of our lakes.
Lodge said he and Drake were surprised to find that even after months in salt water, the fouling scraped from the ship still contained numerous freshwater organisms, including seven freshwater organisms that haven't yet been seen in the lakes .
The fact that Drake and Lodge found hundreds of creatures is more fuel for the argument to keep saltwater ships out of the Great Lakes.