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 2006partial pressure (pC O 2 sea) alongthe sea surface were made,pCO 2 sea average values of 600?atm were measured, inducing anocean-atmosphere flux of 13.55mmol CO 2 m -2 d -1 , our estimationsrevealed that the Todos Santos Bayexported at least 97 ton CO 2 perweek to the atmosphere during thebloom. When the bloom began, thephytoplankton community wasdominated by thecatedinoflagellates (Lingulodiniumpolyedrum, Ceratium furca, C.fusus, Prorocentrum micans andDinophysis spp.) with maximum cellcounts of 7 x 10 6 cells L -1 . At theend, the dominant species were L.polyedrum together with nonthecatedinoflagellates(Gymnodinium spp., Gyrodiniumspp. and Amphidinium spp.) and thediatom Cylindrotheca closterium.Inorganic nutrients, oxygen,temperature and chlorophyll 'a'fluorescence profiles were alsomeasured. A conceptual model isproposed in which the autotrophicrespiration and bacterial oxidation oforganic matter controls thepCO 2 sea levels.PO.15-05Ribosomal DNA quantification inthe dinoflagellates Alexandriumcatenella and Alexandrium taylorifor application in real-time PCRbasedmonitoringSession: PO.15 - MonitoringA. Penna 1 , Luca Galluzzi 1 , ElenaBertozzini 2 , E Garcés 3 , MauroMagnani 11 University of Urbino, PESARO, Italy2 Università degli Studi di Urbino, PESARO,Italy3 Institut de Ciències del Mar,BARCELONA, SpainSeveral molecular methods formonitoring of HAB species havebeen recently developed. Inparticular, quantitative real-timePCR can be used for the detectionand quantification of geneticallydistinct HAB species inenvironmental samples using astandard curve as reference. Thestandard usually consists in thetarget sequences of rDNA genescloned into a plasmid, or in DNAextracted from a known amount ofcultured target cells. When aplasmid is used as standard, it isessential to know the amount of thetarget rDNA copy number per cell.In this study, the rDNA content ofthe HAB species A. catenella and A.taylori was estimated by real-timePCR using specific primersdesigned on the 5.8S rDNA region,and standard curves constructedwith serial dilutions of the clonedtarget sequences. The data wereuseful for quantification of A.catenella and A. taylori in bloomsamples using the real-time PCRbasedapproach. While A. tayloricell quantification was generally inagreement with microscope cellcount, A. catenella cellquantification was underestimatedcompared to standard countingmethod. This could be partiallyexplained by the presence of apseudogene in the 'A.tamarense/catenella/fundyense'complex. Further experiments willbe needed in order to address thisissue.260