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 2006Some species of the diatom genusPseudo-nitzschia are known toproduce the neurotoxin domoic acid(DA) which is responsible foramnesic shellfish poisoning inhumans and domoic acid poisoningin animals. Current phytoplanktonmonitoring by Maryland Departmentof Natural Resources identifiesPseudo-nitzschia in water samplesvia light microscopy as either P.seriata or P. pungens. From 2002to 2006 water samples werecollected throughout theChesapeake Bay (Maryland andVirginia), the coastal bays, and theDelaware coast for culture isolation,toxin analysis and Pseudo-nitzschiaenumeration and speciesidentification via TEM. Four speciesof Pseudo-nitzschia were identifiedin Maryland and Virginia waters (P.multiseries, P. fraudulenta, P.pungens and P. calliantha).Pseudo-nitzschia multiseries, P.calliantha, and P. fraudulenta havebeen isolated from field samples,cultured in the laboratory andsequenced (see poster by H.Bowers, this meeting). Domoic acidwas found in 6 of 14 cultures and insome field samples containingPseudo-nitzschia. Pseudo-nitzschiawas most abundant in the southernportion of the Chesapeake Bay fromJanuary to March. The datasuggest that Pseudo-nitzschia in theChesapeake Bay region is moreabundant at higher salinities andduring colder months.PO.10-44Evidence for neurotoxins fromspecies of the raphidophytegenera Chattonella, Fibrocapsaand HeterosigmaSession: PO.10 - Ecophysiology &autecologyCR Tomas, A. Bourdelais, T Schuster,J NaarUniversity of North Carolina Wilmington,WILMINGTON, NC, United States ofAmericaBlooms of raphidophyte flagellateswere implicated with fish-killingevents, intoxication of bivalves andallelopathic effects on otherphytoplankton. The mode of toxicityis a complex one involving reactiveoxygen species, hemolytic toxins,polyunsaturated fatty acids andneurotoxins. This last toxincategory was inferred from HPLCseparation of compounds that comigratedwith brevetoxins. Theiractual structures and thus finalidentity remained to be defined.This study examined extracts ofChattonella antiqua, C. marina, C.subsalsa, Fibrocapsa japonica andHeterosigma akashiwo. Cultures ofthese organisms were grown in thelaboratory to stationary phase,harvested, extracted with ethylacetate. The dried residue wasresuspended in absolute methanol,filtered and applied to the ELISAassay specific for brevetoxins and toESI and MALDI HPLC Massspectroscopy. All cultures werefound to contain PbTX 2, -3 and -9.While the cellular concentrations ofthese toxins were low this evidenceindicates that among the differingtoxic substances produced inraphidophyte blooms, neurotoxinscannot be excluded as a contributorto their toxicity.PO.15-15Remote sensing for the detectionand monitoring of Microcystisaeruginosa in western Lake Erieand Saginaw Bay, USASession: PO.15 - MonitoringMC Tomlinson 1 , RP Stumpf 1 , GLFahnenstiel 2 , J Dyble 2 , PA Tester 3292