Something good from toxic blooms
Science Centres: Fisheries
Close up view of Karenia brevisulcata, seen through a scanning electron microscope.
In 1998, marine life in Wellington Harbour was decimated by the bloom of a new toxic microalgal species. The species, now named Karenia brevisulcata, was at the time dubbed ‘The Wellington Harbour Toxin’. The spectacular kills of fish, shellfish, sponges, and seaweeds suggested that the active compound(s) produced by this microalga could be used as the active component in antifouling paint. A partnership between NIWA, ESR, Victoria University, and Cawthron Institute was set up to explore the commercial potential of this idea. Conditions for the bulk cultures of the microalga were established, and NIWA and Cawthron Institute provided material to chemists at ESR and Victoria University for the isolation and identification of bioactive compounds.
The fouling of underwater structures by marine organisms is a major cost for shipping and underwater structures, such as oil platforms, pipes (including the intakes to power stations), and aquaculture structures. Figures released in 1994, for example, show that barely visible fouling (5% fouling) on the hull of a supertanker increased the fuel cost for that vessel by $1.5 million per year. There is an urgent need for an antifouling paint to replace current environmentally unfriendly products. The current methods involve painting surfaces with tributyltin (TBT) or copper-based paints. The environmental costs of these paints is substantial. The use of TBT-based antifouling paint in many applications is now due to be phased out by 2005. The contamination levels of TBT and copper can reach very high levels in port areas and have a detrimental effect on marine life in habours. A supertanker in a harbour leaches kilograms of copper or TBT into the water each day. In an effort to reduce inshore contamination, many countries now ban the use of TBT and copper-based antifouling paints for craft less than 25 m in length, and restrict TBT use on ships sailing along the coastline. The huge economic and ecological cost has prompted the search for safe alternatives. Paint formulated from a crude extract of Karenia brevisulcata has shown some promise in early trials. More work is underway to produce a more effective formulation.