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 2006CJ Band-Schmidt 1 , J Bustillos-Guzmán 2 , L Morquecho 2 , I Gárate-Lizárraga 1 , R Alonso-Rodríguez 3 , AReyes-Salinas 2 , K Erler 4 , B Luckas 41 CICIMAR-IPN, LA PAZ BCS, Mexico2 CIBNOR, A. P. 128, 23000 LA PAZ, BCS,Mexico3 Unidad Académica Mazatlán, ICMyL,UNAM, AP 811, MAZATLÁN, SINALOA,82000, Mexico4 Friedrich-Schiller University,Dornburgerstraße 25, 07743 JENA,GermanyIn vitro experiments were performedwith Gymnodinium catenatumGraham strains isolated from theGulf of California (Bahía deMazatlán, Bahía de La Paz, BahíaConcepción) to determine thevariability in toxicity and toxin profileduring different growth phases.Growth rates varied between 0.70and 0.82 day -1 . Highest cell yieldswere reached at 16 and 19 dayswith densities between 1090 and3393 cells mL -1 . Mazatlán and LaPaz strains were more toxic (101 pgSTX eq cell -1 ), compared withstrains from Concepción (13 pgSTX eq cell -1 ). Toxin content did notchange with culture age (0.2 - 0.6pmol PSP cell -1 ). All strainscontained NEOSTX, dcSTX,dcGTX2-3, B1-2, and C1-2 toxins.Concepción strains had the highestcontent of C1, whereas Mazatlánand La Paz strains had a higherpercentage of NEOSTX (23 to52%). Mazatlán and La Paz strainsshowed differences in toxincomposition with culture age.Cultures with higher percentage oflong chains had more NEOSTX,while those with a higher proportionof short chains had a lower contentof NEOSTX. Gulf of Californiastrains are characterized by a highproportion of NEOSTX, and seem tohave evolved particularphysiological responses to theirenvironment that are reflected in thetoxin profile.PO.10-16Metal concentration in freshwatersediments seasonally subjectedto toxin-producingcyanobacterial bloomsSession: PO.10 - Ecophysiology &autecologyMS Baptista, MT VasconcelosCIIMAR, PORTO, PortugalCyanobacteria represent a sink formetals in aquatic environment, asthey are effective metal sorbents,therefore affecting metal speciationand bioavailability. In the ambit of aproject, aiming at investigatingcauses and consequences ofcyanobacterial blooms infreshwater, trace metal (Cd, Co, Cr,Cu, Fe, Mn, Ni, Pb and Zn)concentrations in sediments weremonitored monthly, throughout oneyear, at two sites of Tâmega River(Northeast Portugal): (1) the Marcoreservoir, which has beenseasonally dominated by toxinproducingstrains of Microcystisaeruginosa, from June toSeptember; and (2) the city ofAmarante (ca. 20 km upstream)where no such blooms have beenrecorded. The results show thebaselines of trace metalconcentration to be similar for bothsites, in spite of site (1) being alentic system whereas site (2) is alotic one. However, extreme draughtcharacterized the sampling year; itsinfluence on the results remains tobe ascertained. Maxima of metalconcentrations were registered atboth sites during the bloom event,which, unlike previous years, wasrecorded at site (1) only duringOctober and November (nophytoplankton bloom was recorded131