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 2006Denmark (P. pungens, P. seriata),Norway (P. obtusa), Ukraine (P.pungens) and Washington State,USA (P. australis, P. pungens).Mating and auxospore formationwas only found in P. pungens.Among 10 Portuguese strains of P.pungens, only four were involved inmating and auxospore formation;one of the strains being involved inall matings represents one matingtype. Although the Portuguesestrains showed no sexualcompatibility with strains from otherregions, four succesfull matingsamong the latter were observed.these involved four strains fromUkraine, none of which wascommon to all successful crosses.One of the American strainsproduced auxospores with aUkrainian strain. In all successfulmatings, sexual interaction wasusually detectable one day aftermixing the strains and the mainevents of gamete formation andfusion occurred during late eveningand night. Auxospore growthcontinued for an average of about30 h.PO.10-34RNA content and growth rates inAlexandrium species culturedunder varying environmentalconditionsSession: PO.10 - Ecophysiology &AutecologyL Carter 1 , L Medlin 2 , U John 2 , J Lewis 11 University of Westminster, LONDON,United Kingdom2 Alfred Wegener Institute,BREMERHAVEN, GermanyThree cultures of Alexandrium, A.minutum, A. ostenfeldii and a NorthAmerican strain of A. tamarense,have been studied under variousconditions, including salinitiesranging from 15 psu to 40 psu andtemperatures from 15 °C to 25 °C,and growth curves have beenproduced. Using these growthcurves the specific growth rate hasbeen calculated for thesestrains/species under eachenvironmental condition and thusthe optimal, maximal and minimumgrowth rates for each have beendetermined. Cells have beenharvested from different growthphases and under differing growthconditions and the RNAconcentration per cell measured.These studies are being undertakento validate the quantitative use ofprobes that have been designed toidentify individual species ofAlexandrium (and other nuisancespecies of algae) in waters withdifferent environmental conditions.These probes will form an integralpart of an RNA biosensor that iscurrently being developed within theEU supported Algadec project.PO.10-09Mixotrophy in Dinophysisnorvegica populations in naturalcommunities occurring in theBaltic SeaSession: PO.10 - Ecophysiology &autecologyWF Carvalho, S Minnhagen, E. GranéliUniversity of Kalmar, KALMAR, SwedenDinophysis norvegica is known toform sub-surface blooms, producetoxins and to ingest particulateorganic matter. Althoughphagotrophy of photosyntheticDinophysis species is not a newdiscovery, its role in the ecology ofDinophysis spp. is still unclear. Weused flow cytometry and anacidotropic probe to quantify thefrequency of D. norvegica cellscontaining food vacuoles occurringin natural populations collected from147