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 2006depletion times before a pulse weretested in mixed batch cultures.These experiments showed twocontrasted periods. Heterocapsagrew preferentially for the first threedays of depletion while Alexandriumgrowth was promoted after threedays. This transition correspondedto two favourable physiologicaladaptations of Alexandrium cells:the use of stored intracellularphosphorus for later growth and ahigh capacity to increase its cellphosphate uptake rate. After threedays, Alexandrium consumed thewhole phosphate pulse, reducingHeterocapsa growth. Theseadaptations were confirmed in a P-limited semicontinuous cultureexperiment testing severalphosphate supply frequencies (1, 2,4, 6 days). Alexandrium alwaysoutgrew Heterocapsa and morequickly so for shorter intervals. Theexperiments revealed thatAlexandrium minutum is a 'storagespecialist' and Heterocapsatriquetra rather a 'velocity adapted'species.PO.15-14Solid phase adsorption toxintracking (SPATT) from NewZealand to the Scottish CoastSession: PO.15 - MonitoringJ-P Lacaze, L Stobo, EA Turrell, AScott, E BresnanFisheries Research Services, ABERDEEN,United KingdomAt the XI <strong>International</strong> <strong>Conference</strong>on HABs it was proposed thatSPATT was a simple and sensitivemethod for early warning of shellfishcontamination. SPATT is foundedon the observation that when lownumbers of toxic algae are presentin the water column significantamounts of toxins are dissolved inseawater. Experiments byresearchers from New Zealanddemonstrated a lag betweendetection of dissolved toxinsadsorbed onto porous syntheticresin, phytoplankton peak celldensities and highest toxinconcentrations in shellfish.Preliminary investigations at LochEwe (Scotland) used SPATT in theform of suspended SP-700 resinheld within a mesh bag. Bags weresuspended at 10 m and retrievedand replaced weekly when watersamples for phytoplankton werealso collected. The resin wasextracted and analysed for lipophilictoxins using LC-MS. Okadaic acidand dinophysistoxins were detectedat low concentrations in theabsence of the causativeDinophysis spp. Theseconcentrations increased prior todetection of D. acuminata and D.acuta. Yessotoxin was detectedwhen the causative algae,Protoceratium reticulatum, wasbelow the detection limit using lightmicroscopy. We propose thatSPATT is further developed fordetection of domoic acid andsaxitoxin using other availableresins and computationallydesigned polymers.PO.05-42Evolution of DSP toxicity in amussel-farming raft. Influence ofbacterial faecal contaminationand relative position in the raftSession: PO.05 - Toxin analysisJ Lago, AG Cabado, JM VieitesANFACO-CECOPESCA, VIGO, SpainMarine biotoxins are produced bydinoflagellates or other microalgae.Under optimal ecological conditions,toxic dinoflagellates proliferate,producing a bloom or red tide.212