Breaking down the ballast water problem

Last month at the Biodiversity APPG  we heard from Dr Tom Vance of the Plymouth Marine Laboratory, where he has been working on solutions to the problems of ballast water with Tim Fileman. The topic generated a lot of discussion, so what are the problems with ballast water? Or perhaps the first question is ‘what is ballast water?’ Though clearly important, the issue seems to have snuck out of the limelight, as many marine environmental issues do. In this post we’ll give you an overview of the ballast water contamination and explain what the International Maritime Organisation (IMO) are trying to do about it.

When ships dock their cargo at a port, they have to take on vast amounts of sea water to maintain their stability, which is then dumped at the next destination. Historically, ships used to take on ballast in the form of sand, but this is likely to have transported many non-native plants over here in the past. The potential of sea water ballast to carry non-native organisms from far away countries poses a very real threat and the control measures that have been put in place to date just aren’t enough, Tom informed us.

Apparently a container can carry 100,000 m² ballast water, which can contain a shocking 10, 000 species, from bacteria and viruses to crabs and fish. This was responsible for an outbreak of cholera in Peru in the 1990s. Known invasive non-native species carried by ballast water include the carpet sea squirt, forming a physical barrier on the sea floor to native grazing fish, and the comb jelly, a voracious predator. With new ports and trade routes being created, this is becoming an increasing problem not just for its capacity to spread invasives but also for the effect it can have on the gene pool and adaptability of populations.

Current methods of ballast water control are treatment, by killing all organisms with chlorine, UV treatment, mechanical filtration and offshore exchange. Offshore exchange is thought to reduce the risk of species transfer as the deeper waters are usually less rich in biodiversity than the coastal water. However, Tom points out, it’s still quite possible that a ship could take in millions of detrimental bacteria from an offshore algal bloom. Solid ballast can be used and there are plans for a global network of ‘ballast containers’, however as cargo ships are currently well equipped for pumping ballast water, this is the most economical mechanism.

In the UK,  the political responsibility for addressing this problem falls not with Defra (responsible for the UK invasive non-native strategy) but with the Maritime and Coastguard  Agency. There is no target species list for marine invasives,  In the recent non-natives strategy review, ballast water control was dropped from regulation. So is the UK taking this problem seriously?

40 countries have joined the IMO Ballast Water Management (BWM)Convention) which has laid out guidelines for the treatment of ballast water. However these guidelines are not currently enforced, as the IMO BWM Convention has not yet been ratified. Although enough countries have joined more countries with large shipping tonnage are needed to ratify the Convention; 30 countries and 35% of world gross tonnage are needed in total. It’s countries with really large tonnage, like Singapore that will be needed to reach 35%. The UK is one of the countries that have not joined the Convention, because the government does not believe that the methods are there that will allow them to police the regulations, Tim Fileman explained. However the IMO have provided a feasible policing procedure, Tim added: Port State Officials would check paper work and and the BWM system is in place and only as a last resort would need to take a water sample.

The issue of ballast must be looked at jointly with bio-fouling, which accounts for at least as many marine invasive species and could otherwise negate any positive impact. The IMO have produced guidelines  for reducing biofouling, but it is unlikely that these are implemented regularly. Some countries around the world are taking these problems much more seriously, for example Australia will turn ships away if they don’t think appropriate systems are in place.

This issue of ballast water which has been brought up in the recent discussions on invasive species regulations highlights the antiquity of the shipping industry. To implement the big changes that are needed in technological design of ships, that would not only reduce their ecological footprint but would also increase their efficiency, a big behaviour shift is needed. Most ships still burn bunker fuel, a crude and incredibly polluting oil. It’s doubtful that we would allow this sort of practice on land, so why do we allow it at sea? Marine invasive species ought to be taken just as seriously as their terrestrial counterparts, especially amidst concerns that our marine habitats are being significantly degraded.

There are many challenges in treating the water successfully whether they be economical, political or practical, says Tim, however: “This is a risk reduction exercise at the end of the day and, currently, we are doing very little to reduce that risk…very slowly the shipping industry is being dragged into the 21^st century and forced to consider its environmental impact.”