12th International Conference on Harmful Algae

INTERNATIONAL SOCIETY FOR THE STUDY OF HARMFUL ALGAE12 th <strong>International</strong> <strong>Conference</strong> on Harmful Algae, Copenhagen, Denmark, 4-8 September 2006treatments were 2.2% and 3.6%day -1 , respectively. Copepod faecalpellets had no effect on DA whereasdegradation was as high as 50%day -1 in the mussel faecal mattertreatment. Degradation of OA wasonly found with 4-fold bacteriaabundance and at low rate (0.9%day -1 ). Even after 69 daysexposition to copepod and musselsfaecal matter did not result in OAdegradation. Therefore, OA is amuch more resistant toxin than DA.As the data suggests that somebacteria and digestive enzymesaggregated within mussel faecalmatter shorten the degradation timeof DA, degradation of OA inpresence of other shellfish speciesfaecal matter should be studied.O.06-03Ostreopsis siamensis andpalytoxin-related compounds inNew Zealand: a risk to humanhealth?Session: O.06 - Toxicology 1Presentation time: 09:50 - 10:10LL Rhodes 1 , R Munday 2 , LR Briggs 2 ,PT Holland 1 , CO Miles 2 , J Loader 2 , DJensen 2 , J Cooney 21 Cawthron, NELSON, New Zealand2 AgResearch, HAMILTON, New ZealandOstreopsis siamensis occurs in NewZealand’s sub-tropical waters andproduces potent novel toxins withsome characteristics of palytoxin.Summer blooms of O. siamensishave been linked to massiveseaweed diebacks and to seaurchin (Evechinus chloroticus)mortalities in the far north of NewZealand over the last few years.Optimisation of growth of O.siamensis in vitro, using 30 litrecapacity plastic bags heldhorizontally in light and temperaturecontrolled tanks, has allowed massproduction of the micro-alga forpartial chemical characterisation ofthe toxic compound. Fractionationof the active extracts was guided bya haemolytic neutralisation assay(HNA) for palytoxin. Larvalbioassays using sea urchins andGreenshell musselsTM (Pernacanaliculus) indicated toxicity andextensive acute toxicological studiesusing small mammals confirmedtoxicity by intraperitoneal injection.The assays, including comparativeHNA results, indicate that the novelcompound has an equivalenttoxicity to palytoxin itself. O.siamensis cells were fedincrementally (46 x106 cells overthree days) to shellfish and seaurchins in order to simulate bloomconcentrations and to determine therisk to humans of seafoodcontamination. Results (HNA) wereGreenshell mussels (wholeshellfish), 14.5 µg/kg; scallops(minus hepatopancreas; Pectennovaezealandiae), 7.7 µg/kg; seaurchins, 1.2 µg/kg.O.06-04Effects of algal-producedneurotoxins on brain activity inatlantic salmon (Salmo salar)Session: O.06 - Toxicology 1Presentation time: 10:10 - 10:30Marit Bakke, TE HorsbergNorges Veterinærhøgskole, OSLO, NorwayIn addition to being lethal at highconcentrations, toxins releasedduring harmful algae blooms mayhave implications for fish also insublethal concentrations. Thecellular mechanisms of the toxinsused in this study are welldescribed, however, little is knownabout the effects on the centralnervous system in fish. This studyaimed to look for changes in40