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 2006micron) from 1994-1998, using areceptor-binding assay. Sampleswere selected because they had ahigh Pseudo-nitzschia abundance,and species composition wasdetermined by SEM on manysamples. Most (80% of 106)samples contained DA, withconcentrations ranging from 0.01 to28.65 pg/cell. Preliminary analysisof the data suggests that salinityand dissolved inorganic nitrogenwas higher when DA was presentand there was a significantly higherpercentage of P. multiseries and P.delicatissima present when DA waspresent. Pseudo-nitzschia spp.present in Louisiana coastal watersdo produce DA and, thus, representa threat to human and ecosystemhealth.PO.10-28Delayed fluorescence as anindicator of nutrient limitation inProrocentrum minimumSession: PO.10 - Ecophysiology &autecologyLuka Drinovec 1 , Ilaria Molinari 2 , MajaBerd Zrimec 1 , Marina Monti 3 , AlfredBeran 3 , Alexis Zrimec 11 Institute of Physical Biology,GROSUPLJE, Slovenia2 Dept. Biol, University of Trieste, TRIESTE,Italy3 Inst Nazl. di Oceano e Geofisica Spe,TRIESTE, ItalyPrimary productivity and growth ofalgae is frequently limited by theavailability of nutrients, especiallynitrogen and phosphorus. Theability to identify factors limitingalgal growth is of considerableimportance for marine ecology.In our study, delayed fluorescence(DF) was used to detect changes inphotosynthesis due to nitrogen andphosphorus limitation in laboratorycultures of Prorocentrum minimum.DF is a long-lived light emissionfrom photosynthetic organisms afterillumination. DF decay curve reflectsthe state of the photosyntheticapparatus.Monitoring of DF decay curves oflight-adapted and dark-adaptedsamples, DF intensity versusirradiance response, chlorophyllcontent, cell concentration andmaximum quantum yield of PSII(Fv/Fm) was performed for 4 dayson cultures growing in nitrogen- andphosphorus-limited media.Significant changes in DF kineticswith regard to medium compositionwere observed. Chlorophyll contentand Fv/Fm were reduced comparedto the control for cultures innitrogen-deprived media. Thechanges in DF intensity versusirradiance response showeddifferences in the absorption of light.PO.08-19Uptake and elmination of DST inmussels, oysters and scallopsSession: PO.08 - ToxicologyArne Duinker 1 , P Hovgaard 2 , ASvardal 31 Nat. Inslt. of Nutrition and Seafood Res,BERGEN, Norway2 Sogn og Fjordane University College,SOGNDAL, Norway3 Univ. of Bergen, Sect. for Pharmacology,BERGEN, NorwayMussels (Mytilus edulis), oysters(Ostrea edulis) and scallops(Pecten maximus) were exposed tonatural occurrences of Dinophysisspp. Samples were taken for sixweeks during toxin accumulationfollowed by two months ofelimination in toxin-free waters.Large species differences inaccumulation were seen, withmussels accumulating 10 to 20-foldhigher toxin concentrationscompared to oysters and scallops.165