Many nonindigenous marine species have been introduced into new environments as a result of human activity. Transfers, either intentionally or not, occur by many vectors including ships ballast water which is necessary for safe ship operations and which may be taken on at the port of departure, both discharged and taken on during the voyage, and finally discharged at the arrival port. This movement and release of ballast water means no coastal site, whether it receives direct shipping or not, is immune to ballast-mediated introductions.
In the 1990’s it was estimated that ballast water was responsible for the transportation of over 3,000 species of animals and plants a day.(National Research Council 1995). Ballast in a vessel from the Eastern Mediterranean arrived in the USA with over 50 actively swimming individual fish ranging from 12cm to 36cm in length. The grates over the ballast openings had fallen off allowing the intake of unusually large species. The grates usually allow only a 1cm wide organism to enter. However this can still be some fair sized fish, crustacean or worm.
Hence my suggestion (see Blog 3/3/2011) that the introduction of Lionfish to the East American coast may be due to Ballast discharge. More information regarding the specific types of Lionfish involved and their natural habitat will be gratefully received, and when we can shed more light on this we will let you know.
“stemming the tide” controlling Introductions of Nonindigenous Species by ship’s ballast water , National Research Council 1996 http://www.nap.edu/openbook.php?record_id=5294&page=R1
