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 2006considerably between differentgeographical areas and even withina region and between seasons dueto the presence of different speciesand strains. Traditional methods ofanalysis require substantial samplesizes (e.g. millions of cells) makingit difficult to attribute the presence oftoxins or variations in toxin profilesto individual species. This paper willpresent a new method based upona micro- sampling and extractionprocedure coupled with microcolumnliquid chromatographytandemmass spectrometry (LC-MS). This sensitive method makesanalysis of toxin content withinsingle cells from both cultures andfield samples, a possibility. LC-MSanalyses of spirolides,pectenotoxins and yessotoxins fromintact cells picked from fieldsamples are provided. Variations intoxin profiles were observed insingle cells of A. ostenfeldii from asample collected at Ship Harbour,where we have observedconsiderable variability in toxinprofile in previous years. In clonalcultures of A. ostenfeldii (AOSH1)similar toxin profiles were observed,however there was a strongcorrelation between cell size andtoxin concentration.PO.16-08Significance of benthicrecruitment on the dynamics ofharmful phytoplankton blooms inthe tropicsimportance of benthic resting stagesin seeding planktonic blooms is stillunclear. Using mesocosms, wetested the influence of benthic vs.planktonic inocula on thedevelopment and taxonomiccomposition of tropic phytoplanktoncommunities. The experimentrevealed that the type of inoculuminfluenced bloom development andcommunity structure. Taxa notknown to form resting stages, suchas Pseudo-nitzschia spp. andSkeletonema tropicum were veryabundant in the plankton inoculatedmesocosms. Species compositionwas different when seeded by cellsfrom the benthos. Resting-stageforming species, such asrepresentatives of the genusThalassiosira, thrived in thesediment inoculated mesocosms.These species displayed twotemporally separated density peaksin mesocosms inoculated with bothplankton and sediment. Mostprobably the second peak was aconsequence of germinated restingstages. Our results indicate thatbenthic resting stages provide animportant source for some species.The introduction of benthic restingstages to surface waters can greatlyinfluence species composition of theplankton, and therefore it isimportant that studies of planktonblooms include life history stagesfrom both the sediments and watercolumn.Session: PO.16 – Life cyclesK HärnströmMarine Ecology, GÖTEBORG, SwedenMany harmful marine microalgaehave a benthic resting-stage as partof their lifecycle. Althoughphytoplankton blooms are majorevents in aquatic systems, thePO.14-11187