1. The introduction of invasive marine species into new environments by ships’ ballast water, attached to ships’ hulls and via other vectors has been identified as one of the four greatest threats to the world’s oceans. The other three are land-based sources of marine pollution, overexploitation of living marine resources and physical alteration/destruction of marine habitat.
2. Shipping moves over 80% of the world’s commodities and transfers approximately 3 to 5 billion tonnes of ballast water internationally each year. A similar volume may also be transferred domestically within countries and regions each year. Ballast water is absolutely essential to the safe and efficient operation of modern shipping, providing balance and stability to un-laden ships. However, it may also pose a serious ecological, economic and health threat.
3. Studies carried out in several countries have shown that many species of bacteria, plants and animals can survive in a potent form in the ballast water and sediment carried in ships, even after journeys of several months' duration. Subsequent discharge of ballast water or sediment into the waters of another port may result in the establishment of harmful aquatic organisms and pathogens which may pose threats to indigenous human, animal and plant life, and the marine environment. Although other media have been identified as being responsible for transferring organisms between geographically separated water bodies, ballast water discharge from ships appears to have been among the most prominent. .
CATASTROPHE IN THE WAITING
4. There are thousands of marine species that may be carried in ships’ ballast water; basically anything that is small enough to pass through a ships’ ballast water intake ports and pumps. These include bacteria and other microbes, small invertebrates and the eggs, cysts and larvae of various species. The problem is compounded by the fact that virtually all marine species have life cycles that include a planktonic stage or stages.
5. It is estimated that at least 7,000 different species are being carried in ships’ ballast tanks around the world. The vast majority of marine species carried in ballast water do not survive the journey, as the ballasting and deballasting cycle and the environment inside ballast tanks can be quite hostile to organism survival. Even for those that do survive a voyage and are discharged, the chances of surviving in the new environmental conditions, including predation by and/or competition from native species, are further reduced. However, when all factors are favourable, an introduced species by survive to establish a reproductive population in the host environment, it may even become invasive, out-competing native species and multiplying into pest proportions.
6. As a result, whole ecosystems are being changed. In the USA, the European Zebra Mussel Dreissena polymorpha has infested over 40% of internal waterways and may have required between US$750 million and US$1 billion in expenditure on control measures between 1989 and 2000. In southern Australia, the Asian kelp Undaria pinnatifida is invading new areas rapidly, displacing the native seabed communities. In the Black Sea, the filter-feeding North American jellyfish Mnemiopsis leidyi has on occasion reached densities of 1kg of biomass per m2. It has depleted native plankton stocks to such an extent that it has contributed to the collapse of entire Black Sea commercial fisheries. In several countries, introduced, microscopic, ‘red-tide’ algae (toxic dinoflagellates) have been absorbed by filter-feeding shellfish, such as oysters. When eaten by humans, these contaminated shellfish can cause paralysis and even death. The list goes on, hundreds of examples of major ecological, economic and human health impacts across the globe. It is even feared that diseases such as cholera might be able to be transported in ballast water.
7. India has more than 7500 kms long coast line with12 major ports. Average 5000 ships call in Mumbai port alone and receive 1.8 m tonnes of ballast water each year. Indian coasts are falling prey to the malicious Marine Bio invasion through ballast water. Through port baseline survey and research work, it is established that Mytilopsis sallei, a native of Sub-tropical Atlantic, is found in Mumbai and Vishakhapatnam ports in India.
8. Mytilopsis sallei is a mussel which has invaded Indian sea. This species accumulates in large quantity (10-12 kgs/m ) and creates several maintenance problems with regard to marine structures, equipment and machinery. This species is strong enough to survive in difficult marine climatic conditions and also in polluted and Oxygen deficient water.
TREATMENT TECHNOLOGY
9. Re-ballasting at sea, as recommended by the IMO guidelines, currently provides the best-available measure to reduce the risk of transfer of harmful aquatic organisms, but is subject to serious ship-safety limits. Even when it can be fully implemented, this technique is less than 100% effective in removing organisms from ballast water. Some parties even suggest that re-ballasting at sea may itself contribute to the wider dispersal of harmful species, and that island states located ‘down-stream’ of mid-ocean re-ballasting areas may be at particular risk from this practice. It is therefore extremely important that alternative, effective ballast water management and/or treatment methods are developed as soon as possible, to replace re-ballasting at sea. Significant research and development (R&D) efforts are underway by a number of scientific and engineering research establishments around the world, aimed at developing a more complete solution to this problem.
10. Options being considered include:-
(a) Mechanical treatment methods such as filtration and separation.
(b) Physical treatment methods such as sterilisation by ozone, ultra-violet light, electric currents and heat treatment.
(c) Chemical treatment methods such adding biocides to ballast water to kill organisms.
(d) Various combinations of the above.
11. All of these possibilities currently require significant further research effort. Major barriers still exist in scaling these various technologies up to deal effectively with the huge quantities of ballast water carried by large ships (e.g. about 60,000 tonnes of ballast water on a 200,000 DWT bulk carrier). Treatment options must not interfere unduly with the safe and economical operation of the ship and must consider ship design limitations. Any control measure that is developed must meet a number of criteria, including:
(a) It must be safe and reliable
(b) It must be environmentally acceptable
(c) It must be cost effective.
12. One of the problems currently faced by the global R&D community is that apart from the general criteria above, there are currently no internationally agreed and approved performance standards or evaluation system for the formal acceptance of any new techniques that are developed. In addition, many groups are working in isolation from each other, and there are no formal mechanisms in place to ensure effective lines of communication between the R&D community, governments and ship designers, builders and owners. These are vital if the R&D effort is to succeed.
