The International Maritime Organization's (IMO's) Ballast Water Management (BWM) Convention, which is set to enter into force in September 2017, will not prevent the transfer of invasive aquatic species (IAS) unless there is mandatory legislation in place to prevent biofouling on ships' hulls, says coating and cleaning systems producer Subsea Industries (Subsea).
"The transfer of IAS in ballast water has been addressed with the ratification of the BWM Convention, but currently there is no legislation to prevent the transfer of IAS on ships’ hulls though fouling, only guidelines," said Subsea Chairman Boud Van Rompay.
Van Rompay's comments come following a presentation in December by Dr. Theofanis Karyannis, IMO Marine Environmental Division Technical Officer, at the World Ocean Council’s Sustainable Ocean Summit, which suggested that hull biofouling could be more damaging than ballast water transfers.
Karyannis presentation, provided a number of examples to support the suggestion, such as one case in New Zealand, where biofouling was found to be responsible for 69 percent of IAS compared to just 3 percent from ballast water.
Another example cited findings in Port Phillip Bay, Australia, where 78 percent of IAS was reported to be linked ships' hulls, compared to 20 percent from ballast water.
"The IAS threat is increasing especially since antifouling systems in use since the ban on tributyltin (TBT) are less effective in eliminating hull fouling," said Van Rompay.
"Some species have developed a resistance to copper biocides and are thriving in ports and harbours where copper and organotin residues are high."
Van Rompay says frequent in-water hull cleaning of a hard, inert coating is the best way to prevent IAS translocation, noting that the removal of micro- and macro-fouling from local areas do not pose a risk.
"The only real answer to preventing the spread of IAS is by ensuring that ships sail with a clean hull from their point of origin. Only a non-toxic hard-type coating and regular in-water cleaning can achieve this," said Van Rompay.
"Indeed, many ports and harbours permit the in-water cleaning of this type of coating system. Effective biofouling control is also the most efficient way of reducing fuel consumption and greenhouse gas emissions."
In August, Subsea said it has optimised its range of Ecospeed hard coat marine coatings to reduce hull friction by as much as 40 percent, translating to a similar reduction in bunker consumption.