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 2006diatoms began to decline. Akashiwosanguinea occasionally formedblooms during late fall when alldiatoms had disappeared. Thus,inhibitory effects on growth of A.sanguinea by these diatoms wereexamined under laboratoryconditions. The growth of A.sanguinea was strongly inhibited inbi-algal cultures with S. costatumand Chaetoceros didymium, andslightly inhibited by A. japonica.Furthermore, the growth of A.sanguinea was significantly lower infiltrates (enriched with nutrientmatter) containing medum on whichS. costatum and C. didymium hadgrown thickly than in fresh medium.These results suggest that A.sanguinea was inhibited byallelopathy and cell contact with S.costatum and Chaetoceros sp.blooms in spring and summer. Thegrowth rate of A. sanguineaincreased in the fall, due to theabsence of diatoms anddisappearance of inhibitoryconditions.PO.13-88Red tide due to the dinoflagellateKarenia mikimotoi occurred inHiroshima Bay in 2002Session: PO.13 - Regional eventsYukihiko MatsuyamaNatl Res Inst Fish Env Inland Sea,HIROSHIMA, JapanA large-scale red tide due to harmfuldinoflagellate Karenia mikimotoioccurred in Hiroshima Bay, westernpart of Seto Inland Sea, Japan in2002. Hydrographic and biologicalinvestigations were conducted at amonitoring station from the initialoutbreak to cessation of the redtide. Visible blooms (>10 6 cells/L)occurred 6-22 July during themonitoring station. Maximum celldensity was 1.35 x 10 7 cells/L at themonitoring station and 2.74 x 10 8cells/L in a harbour located near thestation. Water temperature andsalinity during the outbreaks of thered tide ranged from 23.5 to 26.1 °Cand 27.5 to 31.3 psu, respectively.Finfish and oyster aquaculture heldin the bay were devastated by thered tide. Total fisheries damage tofarmed finfish was 950,000 US$.The average mortality of the Pacificoyster Crassostrea gigas and themussel Mytilus galloprovincialiswere 46% and 65%, respectively.Massive kills of shellfish wereprobably caused from a detrimentaleffect of K. mikimotoi because thedeath of shellfish had occurredbefore the lowest values of ofanoxic water (2.0 mg/L in bottom)had developed.PO.01-14A molecular approach to identifyPseudo-nitzschia species innatural samplesSession: PO.01 - GeneticsSM McDonald, D Sarno, A Amato,WHCF Kooistra, A ZingoneStazione Zoologica, NAPLES, ItalyDuring recent years, a number ofnew Pseudo-nitzschia species havebeen described (e.g. Lundholm etal. 2003) that are geneticallydistinct, but difficult to distinguishusing light microscopy and in somecases even with electronmicroscopy. Therefore molecularmethods must be developed toidentify the various species for thepurposes of both monitoringprogrammes and ecological studiesat sea. A PCR-based method wasemployed to assess the seasonaldistribution of Pseudo-nitzschiaspecies during 2004 within the Gulfof Naples. A genus-specific primer237