This e-mail from Great Lakes United's Jen Nalbone is about a report on ships exempted from the Coast Guard's ballast exchange regulations requiring dumping of ballast in the open ocean to rid it of invasive species. As Jen points out, the study shows that most vessels claim the no ballast on board (NOBOB) exemption with predictable consequences for the Great Lakes:
The new NOBOB report by Great Lakes Environmental Research Laboratory was just released. A few of the many important findings in this 285 page report--
Of the NOBOB vessels sampled, residuals can be salty, brackish or freshwater. About 50% of NOBOB tanks sampled had freshwater or brackish residuals.
Those with freshwater residuals present the most serious threat of inoculation of new invaders.
The researchers reviewed the inconsistent records of ships entering the Great Lakes and determined that since the 1990’s the best estimate is that over 90% of ships entering the Great Lakes are NOBOB.
Microbial pathogens were found in residuals (including cholera and giardia), and while the researchers said tanks carrying pathogens not a likely health risk to humans, they recommended more investigation.
Tests showed that, while results varied, ballast water exchange is effective at removing non-indigenous species from ballast tanks. In most cases and across target taxa, ballast water exchange was greater than 90% effective at removing organisms. However, because each tank can contain different organisms which can have a wide variability of tolerance to salt water, it is difficult to generalize BWE efficacy for any given tank.
Find the report “Assessment of Transoceanic NOBOB Vessels and Low-Salinity Ballast Water as Vectors for Non-indigenous Species Introductions to the Great Lakes” on GLERL website at:
http://www.glerl.noaa.gov/res/projects/nobob/products/
Posted by Dave at April 18, 2005 03:22 PM