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 2006knowledge gap and allocated fundsfor a PhD project to investigatesome of the ecological effects ofcylindrospermopsin. Thispresentation will summarise thesefindings in the context of anecological risk assessment.PL.05Anthropogenic influence andclimatic change: effects onharmful algaeSession: PL..05 - Plenary VPresentation time: 08:30 - 09:05Barrie DaleDept of Geosciences, University of Oslo,OSLO, NorwayUnderstanding the possible effectsof anthropogenic influence andclimate change is a criticalrequirement in developing the riskassessments needed for theeffective management of harmfulalgal blooms (HABs). However, thescientific issues involved arecomplex, and the relevant evidenceis sparse, resulting in moreuncertainty than understanding.There are uncertainties concerningHABs (e.g. are HABs increasing,and what are the underlying factorsthat allow some species to bloompreferentially?). There are alsogreat uncertainties regarding theextent of human impact on aquaticenvironments (e.g. it is oftendifficult to differentiate the effects ofeutrophication, pollution, overfishing,etc.). The one thing we arecertain of regarding climate is that itis changing – and it always has.There is a general consensus thatglobal warming is occurring, butgreat uncertainty in predictions offuture temperature increases.These range from 1-2 o (similar tothe Medieval Warm Period, 550-1300AD), to up to several timesmore, with potentially devastatingeffects from ice-cap melting andglobal flooding. Uncertaintiesaffecting assessment ofenvironmental change and its effecton HABs are mostly caused by thelack of adequate time series data.The sedimentary record ofmicrofossils offers one of the fewplausible methods for redressingthis shortfall.O.13-01Different seeding strategieswithin harmful algal bloom (HAB)causing dinoflagellates anddiatomsSession: O.13 - Life cyclesPresentation time: 09:10 - 09:30Shigeru Itakura, S Nagai, M YamaguchiFEIS, HIROSHIMA, JapanDinoflagellates and diatoms arecommon phytoplankters in coastalmarine environments and manyHAB causing species are includedin these two groups. They areknown to produce benthic restingstages (resting stage cells) such asresting cysts, resting spores andresting cells in their life cycle.Benthic resting stages areconsidered to play an important rolein their local reoccurrence. Underfluctuating coastal environmentalconditions, the timing of germinationis a key factor in their seedingstrategy. Newly formed restingstages are in a state of endogenousdormancy. So, they need to bematured (get rid of the dormantstate) prior to their germination.However, even in matured restingstage cells, germination is inhibitedunder unsuitable environmentalconditions. Water temperature, lightintensity and dissolved oxygenseem to have a decisive role in thegermination of matured resting57