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 2006been identified that either consumedirectly DA-producing Pseudonitzschiaor acquire the toxinindirectly. A jellyfish mortality eventwas associated with a Pseudonitzschiabloom and dissolved DAlevels exceeding 120 nM inMonterey Bay, USA, indicating thepossible uptake of DA by jellyfish.This suggests that jellyfish canserve as vectors for transferringtoxin to its predator species (e.g.,turtles, dolphins, tuna) in this andother locations. Laboratoryexperiments using the jellyfishAurelia aurita were performed toassess toxicity (LD50 96 h) ofdissolved DA and the ability of theseorganisms to accumulate the toxin,with toxin levels measured using areceptor binding assay. Resultsdemonstrated that DA was not toxicto A. aurita at the concentrationstested (3 to 250 ng/mL) over a 96 hexposure. During the same timeperiod, a linear relationship wasobserved between the DA level inseawater and in the jellyfish,suggesting diffusion as the primaryuptake mechanism. These findingsdemonstrate that jellyfish canaccumulate DA and thus serve asvectors for trophic transfer andgeographic transport of the toxin asthese contaminated organisms aremoved by ocean currents.PO.05-31The study of cryptic PSP toxicitydepending upon the extractionprocedureSession: PO.05 - Toxin analysisM.J. Botelho, SS Gomes, SMRodrigues, P ValeINIAP-IPIMAR, LISBOA, PortugalThe recent modifications of theextraction solvent for prechromatographicoxidation LCmethod of Lawrence et al. (2004)were tested with shellfish harvestedduring a bloom of Gymnodiniumcatenatum that occurred along theNW coast of Portugal duringautumn 2005. The toxic profile inseveral shellfish species wasobtained using acetic acidextraction, and compared withhydrochloric acid extraction. Sincethe acetic acid doesnot promote the partial conversionof N-sulfocarbamoyl analogues, asobserved with 0.1M hydrochloricacid, underestimation of carbamatetoxins was recorded. A morecomplete conversion of N-sulfocarbamoyl toxins was achievedwith 1 M hydrochloric acid, meaningcryptic toxicity was still left in thesample.PO.01-01Genetic characterization ofPseudo-nitzschia speciesisolated from the ChesapeakeBay, Maryland USASession: PO.01 - GeneticsHA Bowers 1 , A Thessen 2 , DW Oldach 1 ,D Stoecker 21 University of Maryland, BALTIMORE,United States of America2 University of Maryland Center for Envir,CAMBRIDGE, United States of AmericaRecently, domoic acid-producingPseudo-nitzschia species wereisolated from the Chesapeake Bay,Maryland (see poster by A.Thessen, this meeting). AlthoughPseudo-nitzschia has beenidentified previously in this regionvia light microscopy, there has beenvery little work performed to identifythem via electron microscopy,genetics and toxin analyses. Aspart of the characterization of theseisolates, we sequenced tworibosomal RNA loci: the 28S largesubunit and the region spanning137