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Colonization of invasive species in marine waters and their detrimental effects to valuable ecosystems and resources has raised concerns about the migration of non-indigenous species between bioregions. Increased world trade and subsequent transport of goods across the oceans and along coastlines has enhanced concerns about harm to valuable resources due to biofouling on ships. This has been highlighted by the inclusion of a new agenda item for the International Maritime Organization Marine Environment Protection Committee, and the recent formation of a correspondence group under the Sub-committee on Bulk Liquid and Gases. This sub-committee and correspondence group is focusing on the development of international measures for minimizing the translocation of invasive aquatic species through biofouling of ships.
Some findings of this sub-committee include:
1) Bio-fouling organisms are extremely diverse, and more than 4000 species have been recorded.1
2) Historically vessels were heavily fouled and able to transport species over large distances.2 With improved anti-fouling technology the substantial growth that had been observed on vessels after less than 1 year were not being observed after in-service periods of up to 5 years.3,4 Consequently bio-fouling as a vector for invasive species transfer was thought to be adequately mitigated. However, this has proved to be a false perception and there is now a sizeable body of knowledge which indicates bio-fouling remains a significant vector for species translocations. This includes both analysis of established non-indigenous species5,6,7 and direct experimentation or observation of fouling assemblages.8 A recent key finding has been that while the main hull of a vessel may be kept relatively clear of bio- fouling, there are “niche” areas where fouling organisms can accumulate.9,10
3) Biofouling has been estimated to be a more significant transport mechanism than ballast water for the introduction of invasive species in many waters including Hawaii, New Zealand, Port Phillip Bay, Australia, North America and the North Sea.10 4) Invasive species from fouling is a significant threat to marine ecosystems and invasions have in some incidences been devastating to an ecosystem; examples include the Japanese kelp in New Zealand and Australia, the red seaweed in Hawaii, mussels including species of Perna in the Gulf of Mexico, Mytilus in South Africa, Limnoperna in Brazil and Dreissena in North America and Europe.10 5) Invasive species can be a threat to human health. Although there is little direct evidence of human health impacts from the transport of species in bio-fouling, the complexity and diversity of bio-fouling assemblages suggests the potential for this. For example, crabs can be transferred with bio-fouling and the Chinese mitten crab is a secondary intermediate host for the Asian lung fluke which has caused deaths in Asia.10 6) Invasive species and biofouling can harm resources including aquaculture, fisheries, factories and water supply facilities. Bio-fouling on vessels and other marine structures can interfere with the operation of submerged equipment, impose increased loading and accelerate corrosion on coastal and offshore marine structures, cause navigation buoys to
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