Managing Ballast Water to Reduce the Risk of Invasion by Nonindigenous Species

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Managing Ballast Water to Reduce the Risk of Invasion by Nonindigenous Species

Ballast water discharged from ships is the most important vector for the introduction and transfer of invasive aquatic species into the Great Lakes–St. Lawrence Basin. According to the research results of a team of experts at Environment Canada, treatment methods other than the exchange of ballast water could prove effective in reducing the risk of invasions while posing no danger to the environment.

Since the adoption in Canada in 1989 of the first Voluntary Guidelines for the Control of Ballast Water Discharges from Ships Proceeding to the St. Lawrence River and the Great Lakes, the number of times ship-mediated nonindigenous species have been mentioned has declined from nine or ten per decade in the 1960s, 1970s and 1980s to five mentions in the 1990s (de Lafontaine and Costan, 2002).

The risk of exotic invaders in the Great Lakes–St. Lawrence Basin remains nonetheless. Since the guidelines were voluntary, their enforcement depended on the goodwill of ship operators. Furthermore, studies have revealed the presence of organisms living in the waste water and ballast tanks of the offloaded ships. Thus, when ships discharge their ballast water in ports before loading their freight, these organisms can end up in the receiving body of water.

Montreal at the end of the 19th century. At the time, ships carried solid ballast to ensure their stability. Although solid ballast was responsible for the introduction of many species of exotic plants, liquid ballast hastened the proliferation of nonindigenous wildlife species in the Great Lakes–St. Lawrence ecosystem.

Implementing regulations to manage ballast water

With the particular aim of making it mandatory to apply those measures that had previously been wholly voluntary, the Government of Canada brought into effect, in June 2006, the Ballast Water Control and Management Regulations. According to these regulations, all ships arriving from beyond the exclusive economic zone (EEZ) and entering waters under Canadian jurisdiction must, as the case may require:

exchange their ballast water;
treat their ballast water;
discharge their ballast water to a reception facility;
retain their ballast water on board ship.

The St. Lawrence Seaway

Four thousand ships transporting a total of 44 million tonnes of goods worth $7 billion ply the Seaway every year. Maritime transport is not without consequence, however; close to half of all the exotic species introduced into the St. Lawrence River over the last century entered this way (de Lafontaine and Costan, 2002).

Map: Location the ballast-water exchange areas of the St. Lawrence

Modified from Bourgeois et al. 2001.

The International Convention for the Control and Management of Ships’ Ballast Water and Sediments was proposed in February 2004 by the International Maritime Organization (IMO). Signatories to the Convention, including Canada, agree to take measures to prevent, reduce and ultimately eliminate the transfer of harmful aquatic organisms or pathogens by controlling and managing ship ballast water. The Convention will only enter into force 12 months after 30 countries representing 35% of the world’s tonnage ratify it.

After first advising Transport Canada of their inability to exchange ballast water in the open sea, ships may, beginning on December 1 and ending on May 1, conduct exchanges in the Laurentian Channel east of 63° west longitude, where the water is at least 300 m deep, according to the Ballast Water Control and Management Regulations.

Treatment methods under study

In October 2003, Transport Canada and the Sea Grant College Program of the Massachusetts Institute of Technology (MIT) co-sponsored an interdepartmental and multilateral workshop on current practices in ballast-water management. Yves de Lafontaine, a research scientist at Environment Canada, was one of the participants.

According to de Lafontaine, “If we are to reduce the risk of exotic species invading the Great Lakes–St. Lawrence system, we have to apply alternative treatment methods — methods that are both effective and environmentally sound — to ballast water prior to its discharge in order to protect the receiving environment.” [translation]

The treatment of ballast water onboard ship represents a replacement to exchanging water in the open sea. A team of experts at Environment Canada is currently working to evaluate the effectiveness of chemical and biological treatments designed to eliminate organisms in the ballast tanks while ensuring that the discharge of treated water does not pose a danger to the environment.

The Peraclean® Ocean chemical treatment

The effectiveness of Peraclean® Ocean, a degradable biocide using peracetic acid (PAA) and hydrogen peroxide (H₂O₂) as active ingredients, was demonstrated during tests in mesocosms and under real ballast conditions. The results showed that even in very cold freshwater conditions, the treatment could effectively destroy the aquatic organisms found in ballast water. However, the treatment also chemically alters the quality of the treated water, making it toxic for a certain period of time, and this could have an impact on the receiving environment. To learn more, see Peraclean® Ocean for ballast water treatment: First onboard ship evaluation of effectiveness as a biocide in very cold temperatures.

Biological deoxygenation

A second treatment method is biological deoxygenation of the water. This method consists of rapidly reducing the dissolved oxygen concentration in the water, leading to the mass mortality of aquatic organisms. According to the research results, the method appears to be technically feasible and satisfies many environmental criteria, in both fresh and salt water, at temperatures varying from near zero to 25°C. The bioreactive process uses a non-fermenting yeast mixture, with the addition of nutrients, that requires a high level of oxygen.

Challenges remain, however—particularly in terms of how to control the biological quality of the discharge so as to protect the quality of the receiving environment. The results of laboratory experiments show, on the one hand, that it is now possible to use UV spectrophotometry for rapid quantitative assessment of the bioreactive deoxygenation treatment onboard ship. On the other hand, efforts to determine the potential toxic effect of this treatment have shown that it does not pose a danger to the receiving environment. See the 42nd conference of the Canadian Association on Water Quality.

Literature

Bourgeois, M., M. Gilbert, and B. Cusson. 2001. Évolution du trafic maritime en provenance de l’étranger dans le Saint-Laurent de 1978 à 1996 et implications pour les risques d’introduction d’espèces aquatique non indigènes. Canadian Technical Report of Fisheries and Aquatic Sciences 2338: viii + 34 pp.

de Lafontaine, Y. and S. Despatie. 2006. Evaluation of effectiveness and potential toxicological impact of the Peraclean® Ocean ballast water treatment technology. Water & Science Technical Report Series, N^o AEP-TN07-001, 39 pp.

de Lafontaine, Y. and N. Simard. 2004. “Alternative Areas or Alternative Methods? Lessons from the Gulf of St. Lawrence,” in J. Pederson, (ed.), Ballast Water Exchange: Exploring the Feasibility of Alternate Ballast Water Exchange Zones in the North Atlantic. Report of a workshop held October 27 and 28, 2003, in Halifax, Nova Scotia. Massachusetts Institute of Technology, Cambridge, Massachusetts. pp. 63-70.

de Lafontaine, Y. and G. Costan. 2002. “Introduction and Transfer of Alien Aquatic Species in the Great Lakes–St. Lawrence River Drainage Basin,” in R. Claudi, P. Nantel and E. Muckle-Jeffs (eds.), Alien Invaders in Canada’s Waters, Wetlands and Forests. Natural Resources Canada, Canadian Forest Service. Ottawa, Ontario.

Jenkins, P.T. and Associates Ltd., Marine Consulting and Management Services.