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 2006and their prey are difficult to monitorusing standard microscopy. Thehigh magnification needed todistinguish between HAB and preyspecies results in shallow depths offield and prevents tracking the 3-dimensional paths of multipleswimming organisms. Microscopicdigital holography overcomes thislimitation by using numericalreconstruction to provide in-focusviews of all the organisms within a 3mm depth. The accuracy in thetracking procedure is sufficient toprovide fully 3-dimensionaltrajectories from one view. Thetechnique is applied to cultures oftoxic and nontoxic strains ofKarlodinium veneficum with andwithout a predator, Oxyrrhis marina,as well as Pfiesteria piscicida withand without its algal prey,Rhodomonas. Typical swimmingbehaviors include helical swimmingand conspecifics revolving aroundeach other. Karlodinium individualsare observed to have swimmingspeeds ranging from 0.05 to 0.5mm/s and Pfiesteria cells 0.1-1mm/s. We also observe a changein the average swimming speed ofP. piscicida from 0.5 mm/s inisolation to 0.9 mm/s in thepresence of its prey, Rhodomonas.PO.16-06Effects of temperature and lighton benthic cell germination andgerminated cell survival of thenoxious raphidophyteHeterosigma akashiwoSession: PO.16 – Life cyclesTomoyuki Shikata 1 , S Nagasoe 2 , TMatsubara 2 , Y Yamasaki 2 , YShimasaki 2 , Y Oshima 2 , T Honjo 2FUKUOKA, Japan2 Graduate School, Kyushu University,FUKUOKA, JapanThe effects of temperature and lighton germination of benthic cells andsurvival of the germinated motilecells of Heterosigma akashiwo wereexamined with bottom sedimentsincluding the benthic cells of thisorganism. The motile cellsappeared in a temperature rangefrom 5 °C to 30 °C in suspensionsof mixed sediment and seawaterwithin three weeks, but attemperatures ≦12 °C, the cellnumbers were markedly low and theappearance was delayed. When thesamples, incubated at eachtemperature, were incubatedat 20°C, only few motile cells appeared.In suspensions incubated in the lightor dark, despite counting motilecells at six-hourly intervals, thenumber of motile cells germinated inthe dark was significantly lower thanthose in the light. Subsequently,when the suspension incubated inthe dark was exposed to light, onlya few newly germinated motile cellswere observed. These resultsindicate that germination of thebenthic cells is independent oftemperature and light if thesediment is suspended intoseawater, but the speed of thegermination process depends ontemperature, and survival of thecells just after germination isstrongly affected by temperatureand light.PO.15-27Development of a simple andsensitive monitoring method forthe shellfish-killing dinoflagellateHeterocapsa circularisquamausing real-time PCR assaySession: PO.15 - MonitoringT Shiraishi 1 , R Kamikawa 1 , Y Sako 1 , STaino 2 , Y Hayashi 2 , I Imai 11 Kyoto University, KYOTO, Japan279