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FOOD SAFETY Scientists learn how to control ���RED SEAS��� BY DOROTHY-JEAN MCCOUBREY And Moses��� lifted up the rod, and smote the waters that were in the river, in the sight of Pharaoh, and in the sight of the servants; and all the waters that were in the river turned to blood. And the ���sh that were in the river died; and the river stank, and the Egyptians could not drink of the water of the river; and there was blood throughout the land of Egypt. Exodus 7:20-21 s this excerpt from the Bible highlights, the harmful effects of red tides have been acknowledged as early as the writing of the Old Testament. Interestingly, not all ���red tides��� are harmful and often it is the invisible harmful algal blooms which are the most lethal to humans, birds and marine life. Algae (phytoplankton) are microscopic plant cells that live naturally in seawater. They are necessary for the life force of the planet being the primary oceanic energy producers and forming the base of the marine food chain. In the presence of sunlight and suf���cient nutrients, these single-celled plants photosynthesize and multiply, creating a ���bloom��� that feeds everything from fellow microbes to large ���sh. Among the thousands of species in the ocean, only a few dozen toxins pose a toxic natural hazard and these tyrants are known as Harmful Algal Blooms. No one is sure of the reason, but it seems over the last two decades HABS have increased in frequency, intensity and geographical distribution throughout the world causing signi���cant public health and economic problems. There was no historical evidence of any HAB problems in New Zealand waters until the summer of 1993 when the North Island was suddenly affected by Neurotoxin Shell���sh Poisoning phytoplankton. Since then most of the coastline around the North, South and Stewart Islands, has been affected by many species of HABs, capable of causing a wide range of toxicological symptoms. Scientists all over the world are studying HABS so they regularly share information at international forums. Over 400 scientists attended the 15th International Conference on Harmful Algae, held in Gyeongnam, Korea, October 29 to November 2, 2012. The conference topics included climate change, allelochemicals in marine food webs, HAB management in the Western Paci���c, cyanotoxins, issues relating to bottom dwelling toxins such as palytoxins and ciguatera ���sh poisoning, and HAB mitigation strategies. New Zealand is internationally recognised for the calibre of our HAB scientists, as evidenced by the team who participated in the Korean conference. Lesley Rhodes and Kirsty Smith both gave lectures on pinnatoxins, while others displayed posters on their scienti���c work including Tim Harwood on the Lawrence method now used in New Zealand to identify Paralytic Shell���sh Toxin, Lincoln McKenzie on Alexandrium blooms in the Marlborough Sounds, Feng Shi on the toxicity of Karenia species to ���sh, Hoe Chang on Pseudochattonella verrusculosa toxic to ���sh in the Wellington Harbour and Lesley Rhodes on the national micro algae culture collection held at Cawthron Institute. There were many important scienti���c breakthroughs A announced at the Korean conference including: ��� A metabolome approach to identify novel toxins from harmful algae. Metabolomics is the study of the unique chemical ���ngerprints that speci���c cellular processes leave behind. ��� The discovery of acyl ester metabolites of gymnodimines by Liquid Chromatography ��� Mass Spectometry (LCMS). ��� Identi���cation of novel azaspiracids from the diarrhetic toxin producing Azadinium genus ��� The bulk isolation of Pectenotoxins from cultured Dinophysis species. ��� A talk on major ���sh kills by P���esteriaceae at a trout ���sh farm in Denmark. ��� The determination of the saxitoxin genes in dino���agellates. ��� Use of Zebra ���sh embryos to test for polymethoxy-1alkenes isolated from cyanobacteria, which is a potential environmental and health risk. A major highlight for conference participants was the demonstration of clay dispersal as a mitigation technique for HAB (See photo). Korea has intensive ���sh cage aquaculture, which can be badly affected by the ���sh killing dino���agellate Cochlodinium polykrikoides, so the clay is used to ���occulate the toxins protecting the ���sh during an event. The clay is a natural and almost inert material which the Koreans believe causes little environmental damage when used during HAB events. Dr Lesley Rhodes of Cawthron Institute tells me that the Korean conference was a great success, with new scienti���c discoveries unveiled and collegial relationships af���rmed by the international HAB experts. New Zealand will be hosting the 16th International Conference on Harmful Algae in Wellington, October 27 to 31, 2014. It promises to be another stimulating and productive event. If anyone wants to know check out the website www.icha2014nz.com or contact Lincoln MacKenzie or Lesley Rhodes at Cawthron Institute. JANUARY/FEBRUARY 2013 ��� Koreans using clay dispersal as a mitigation technique in HAB event NZ AQUACULTURE ��� 11