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Bibliographie de l'Institut Maurice-Lamontagne

Plantes - Dinoflagellés / Alexandrium tamarense / 

DUFOUR, R., H. BENOIT, M. CASTONGUAY, J. CHASSÉ, L. DEVINE, P. GALBRAITH, M. HARVEY, P. LAROUCHE, S. LESSARD, B. PETRIE, L. SAVARD, C. SAVENKOFF, L. ST-AMAND, M. STARR, 2010. Ecosystem status and trends report: Estuary and Gulf of St. Lawrence ecozone. Rapport sur l’état et les tendances des écosystèmes : écozone de l’estuaire et du golfe du Saint Laurent. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche; 2010/030, 193 p.

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Le présent document a été produit dans la foulée du programme national sur l'état et les tendances des écosystèmes et traite de l'écozone de l'estuaire et du golfe Saint-Laurent. Il s'articule autour de l'état et des tendances de plusieurs espèces marines ainsi que de certaines variables physico-chimiques importantes de l'écosystème. Le rapport national sur l'état et les tendances des écosystèmes servira à établir les priorités pour un programme national sur la biodiversité et intègrera de l'information écosystémique de portée nationale et provinciale. Il traitera de nombreuses écozones terrestres et marines d'envergure.

FAUCHOT, J., F.J. SAUCIER, M. LEVASSEUR, S. ROY, B. ZAKARDJIAN, 2008. Wind-driven river plume dynamics and toxic Alexandrium tamarense blooms in the St. Lawrence Estuary (Canada) : a modeling study. Harmful Algae, 7(2) : 214-227.

[Résumé disponible seulement en anglais]
In the lower St. Lawrence estuary (LSLE, eastern Canada), blooms of the toxic dinoflagellate Alexandrium tamarense are a recurrent phenomenon, resulting in paralytic shellfish poisoning outbreaks every summer. A first coupled physical-biological model of A. tamarense blooms was developed for this system in order to explore the interactions between cyst germination, cellular growth and water circulation and to identify the effect of physical processes on bloom development and transport across the estuary. The simulated summer (1998) was characterized by an A. tamarense red tide with concentrations reaching 2.3 × 106 cells L-1 along the south shore of the LSLE. The biological model was built with previously observed A. tamarense cyst distribution, cyst germination rate and timing, and A. tamarense growth limitation by temperature and salinity. The coupled model successfully reproduced the timing of the A. tamarense bloom in 1998, its coincidence with the combined plumes from the Manicouagan and Aux-Outardes (M-O) rivers on the north shore of the estuary, and the temporal variations in the north-south gradients in cell concentrations. The simulation results reveal that the interaction between cyst germination and the estuarine circulation generates a preferential inoculation of the surface waters of the M-O river plume with newly germinated cells which could partly explain the coincidence of the blooms with the freshwater plume. Furthermore, the results suggest that the spatio-temporal evolution of the bloom is dominated by alternating periods of retention and advection of the M-O plume: east or north-east winds favor the retention of the plume close to the north shore while west or north-west winds result in its advection toward the south shore. The response of the simulated freshwater plume to fluctuating wind forcing controls the delivery of the A. tamarense bloom from the northern part of the estuary to the south shore. In addition, our results suggest that a long residence time of the M-O plume and associated A. tamarense population in the LSLE during the summer 1998 contributed to the development of the red tide. We thus hypothesize that the wind-driven dynamics of the M-O plume could partly determine the success of A. tamarense blooms in the LSLE by influencing the residence time of the blooms and water column stability, which in turn affects A. tamarense vertical migrations and growth.©2007 Elsevier B.V.

FAUCHOT, J., M. LEVASSEUR, S. ROY, R. GAGNON, A.M. WEISE, 2005. Environmental factors controlling Alexandrium tamarense (dinophyceae) growth rate during a red tide event in the St. Lawrence Estuary (Canada). J. Phycol., 41(2): 263-272.

[Résumé disponible seulement en anglais]
The dinoflagellate Alexandrium tamarense (Lebour) Balech 1985 is responsible for recurrent outbreaks of paralytic shellfish poisoning in the St. Lawrence Estuary. In July 1998, an A. tamarense red tide developed in the estuary with maximum cell concentrations reaching 2.3 × 106 cells·L-1 in brackish surface waters. To estimate the growth rate of these cells, surface water samples from different locations and days during the bloom were incubated for 5 to 9 days under in situ temperature and light conditions. Growth rates varied both spatially and temporally between 0 and 0.55 day-1, reaching the maximum growth rate reported for this species in culture. High growth rates were measured even during the peak of the red tide, suggesting that the extremely high cell concentrations observed did not solely result from aggregation or physical concentration but also involved active cellular growth. Alexandrium tamarense cells were found over a large range of salinity (20.8-29.5 psu), but high densities and significant growth were only measured when salinity was lower than 24.5 psu. Under these conditions, the number of divisions achieved by A. tamarense was proportional to the amount of nitrate available at the beginning of the incubations, whereas variations in growth rate were apparently controlled by the availability of phosphate. We hypothesize that the ability of A. tamarense to perform vertical migrations and acquire nitrate at night pushes this species toward phosphate limitation in the St. Lawrence Estuary.©2005 Phycological Society of America

GAGNON, R., M. LEVASSEUR, A.M. WEISE, J. FAUCHOT, P.G.C. CAMPBELL, B.J. WEISSENBOECK, A. MERZOUK, M. GOSSELIN, B. VIGNEAULT, 2005. Growth stimulation of Alexandrium tamarense (dinophyceae) by humic substances from the Manicouagan River (eastern Canada). J. Phycol., 41(3): 489-497.

[Résumé disponible seulement en anglais]
In the St. Lawrence Estuary, annual recurrent blooms of the toxic dinoflagellate Alexandrium tamarense L. Balech are associated with brackish waters. Riverine inputs are suspected to favor bloom development by increasing water column stability and/or by providing growth stimulants such as humic substances (HS). A 17-day culture experiment was conducted to evaluate the importance of HS as growth factors for A. tamarense. Nonaxenic cultures were exposed to four HS extracts from three different sources: humic and fulvic acids isolated from the Manicouagan River, Quebec, Canada; humic acids from the Suwannee River, Georgia, United States; and a desalted alkaline soil extract. For each extract, four concentrations were tested as supplements to the artificial Keller medium, a nitrate-rich algal culture medium. Additions of HS from all sources significantly enhanced the overall growth rates relative to the controls. Concentrations of HS, estimated by UV spectrophotometry, remained constant throughout the exponential growth phase, suggesting that the HS were acting mainly as growth promoters during our experiment. Dose-response curves indicated that HS could increase the growth rate of A. tamarense even at low concentrations, such as those encountered in the St. Lawrence Estuary. Our results support the hypothesis that HS from the Manicouagan River plume can stimulate the development of toxic dinoflagellate blooms.©2005 Phycological Society of America

MERZOUK, A., M. LEVASSEUR, M. SCARRATT, S. MICHAUD, M. GOSSELIN, 2004. Influence of dinoflagellate diurnal vertical migrations on dimethylsulfoniopropionate and dimethylsulfide distribution and dynamics (St. Lawrence Estuary, Canada). Can. J. Fish. Aquat. Sci., 61: 712-720.

Nous avons étudié l'influence de la migration verticale journalière des dinoflagellés Alexandrium tamarense et Scrippsiella trochoidea sur la dynamique du déméthylsulfoniopropionate (DMSP) et du sulfure de diméthyle (DMS) dans une expérience de type lagrangien de 34 h dans l'estuaire du Saint-Laurent en juillet 2000. Le DMSP particulaire (DMSPp), le DMSP dissous (DMSPd) et le DMS suivent tous des patterns journaliers avec des concentrations minimales durant la nuit et des concentrations maximales vers midi. Les concentrations de DMSPp sont en corrélation avec l'abondance des deux dinoflagellés à migration verticale qui sont riches en DMSP. Le rapport DMSPp:Chl a suit des variations journalières semblables, ce qui indique une néosynthèse de DMSP induite par la lumière durant le jour. Les variations journalières du rapport DMS:Chl a indiquent que l'accumulation de DMS vers midi résulte de réactions physiologiques des algues et (ou) des bactéries à la lumière. La production biologique brute de DMS et la consommation bactérienne de DMS sont déphasées, ce qui entraîne des fluctuations rapides de DMS. Ces résultats démontrent que dans les systèmes dominés par des dinoflagellés riches en DMSP et contenant des DMSP lyases, les concentrations de DMS peuvent varier par un facteur allant jusqu'à 10 au cours d'une période 24 h. On doit tenir compte de ces variations journalières lorsqu'on estime la contribution de tels systèmes au flux de DMS de la mer à l'atmosphère.©2004 NRC Canada

BLASCO, D., M. LEVASSEUR, E. BONNEAU, R.. GELINAS, T.T. PACKARD, 2003. Patterns of paralytic shellfish toxicity in the St. Lawrence region in relationship with the abundance and distribution of Alexandrium tamarense. Sci. Mar. (Barc.), 67(3): 261-278.

MICHAUD, S., M. LEVASSEUR, G. DOUCETTE, G. CANTIN, 2002. Particle size fractionation of paralytic shellfish toxins (PSTs): seasonal distribution and bacterial production in the St. Lawrence estuary, Canada. Toxicon, 40: 1451-1462.

WEISE, A.M., M. LEVASSEUR, F.J. SAUCIER, S. SENNEVILLE, E. BONNEAU, S. ROY, G. SAUVÉ, S. MICHAUD, J. FAUCHOT, 2002. The link between precipitation, river runoff, and blooms of the toxic dinoflagellate Alexandrium tamarense in the St. Lawrence. Can. J. Fish. Aquat. Sci., 59: 464-473.

Les floraisons du dinoflagellé toxique Alexandrium tamarense, responsable de l'intoxication paralysante par les mollusques, sont des événements annuels récurrents dans l'estuaire et le golfe du Saint-Laurent, Québec, Canada. L'analyse des données d'abondances de A. tamarense entre 1989 et 1998 à Sept-Îles, un site présumé d'initiation des floraisons dans le nord-ouest du golfe du Saint-Laurent, montre que l'initiation, la durée et l'ampleur des floraisons toxiques de A. tamarense varient d'une année à l'autre. Les données hydrologiques et météorologiques indiquent que les précipitations, le débit de la rivière Moisie et le vent sont étroitement liés au patron annuel de floraison. Les 10 années de résultats démontrent que dans ce système : (i) un débit élevé de la rivière Moisie dû à une importante crue printanière ou à de fortes précipitations durant l'été et l'automne peut déclencher des floraisons de A. tamarense, (ii) un débit élevé de la rivière Moisie combiné à une période de vents faibles (< 4 m times s-1) favorise le développement continu des floraisons et (iii) des vents > 8 m times s-1 dispersent et mettent fin aux floraisons. La salinité, qui reflète l'état général de la colonne d'eau en termes d'apport d'eau douce et de stabilité, démontre une forte corrélation négative avec la probabilité d'observer des cellules de A. tamarense à cette saison. Ce paramètre pourrait donc être utilisé comme outil pour prédire la présence de A. tamarense dans ce système.

LEVASSEUR, M., L. BÉRARD-THERRIAULT, E. BONNEAU, S. ROY, 1998. Distribution of the toxic dinoflagellate Alexandrium ostenfeldii in the Gulf of St. Lawrence, Canada. Pages 54-57 in B. Reguera, J. Blanco, M.L. Fernandez & T. Wyatt (ed.). Harmful algae. Xunta de Galacia and Intergovernmental Oceanographic Commission of UNESCO.

PEREZ, C., S. ROY, M. LEVASSEUR, D.M. ANDERSON, 1998. Control of germination of Alexandrium tamarense cysts from the Lower St. Lawrence Estuary (Canada). J. Phycol., 34: 242-249.

GOSSELIN, S., L. FORTIER, J.A. GAGNÉ, 1989. Vulnerability of marine fish larvae to the toxic dinoflagellate Protogonyaulax tamarensis. Mar. Ecol. Prog. Ser., 57: 1-10.

CEMBELLA, A.D., J.-C. THERRIAULT, 1989. Population dynamics and toxin composition of Protogonyaulax tamarensis from the St. Lawrence Estuary. Pages 81-84 in T. Okaichi, D.M. Anderson & T. Nemoto (ed.). Red tides : biology, environmental science and toxicology. Elsevier, New York.

CEMBELLA, A.D., F.J.R. TAYLOR, J.-C. THERRIAULT, 1988. Cladistic analysis of electrophoretic variants within the toxic dinoflagellates genus Protogonyaulax. Bot. Mar., 31: 39-51.

CEMBELLA, A.D., J. TURGEON, J.-C. THERRIAULT, P. BÉLAND, 1988. Spatial distribution of Protogonyaulax tamarensis resting cysts in nearshore sediments along the north coast of the Lower St. Lawrence Estuary. J. Shellfish Res., 7: 597-609.

CEMBELLA, A.D., J.-C. THERRIAULT, P. BÉLAND, 1988. Toxicity of cultured isolates and natural populations of Protogonyaulax tamarensis from the St. Lawrence Estuary. J. Shellfish Res., 7: 611-621.

CEMBELLA, A.D., J.J. SULLIVAN, G.L. BOYER, J.R. TAYLOR, R.J. ANDERSEN, 1987. Variation in paralytic shellfish toxin composition within the Protogonyaulax tamaronsis/catenella species complex; red tide dinoflagellates. Biochem. Syst. Ecol., 15(2): 171-186 .

[Résumé disponible seulement en anglais]
Unialgal isolates of the Protogonyaulax (–Gonyaulax) tamarensis/catenella species complex, a group of dinoflagellates which causes paralytic shellfish poisoning (PSP), were subjected to toxin analysis by HPLC. Protogonyaulax isolates from widely separated geographical locations were compared, including the northeastern Pacific (British Columbia and Washington State), eastern Canada, Portugal, the United Kingdom and New Zealand. Two distantly related gonyaulacoid species were also analyzed, but the presence of PSP toxins was not detected. Although Protogonyaulaxisolates varied markedly in total toxin concentration and toxicity, even through the culture cycle, the toxin ratios of individual isolates were distinctive and relatively constant. No toxins were detected in the Plymouth (U.K.) isolate of P. tamarensis, from the species type locality. Two isolates from Vancouver Island (British Columbia), which were previously considered to be non-toxic according to the mouse bioassay, revealed weak toxin spectra by HPLC. Within populations from English Bay (British Columbia) the toxin profiles of tamarensoid isolates tended to be conservative. However, this was not the case for the catenelloid forms from Washington State, which displayed a greater degree of toxin heterogeneity. Significantly, there was no identifiable relationship between toxicity or toxin profiles and the morphological characteristics conventionally used to separate the two dominant morphotypes into species within this species complex.©1987 Pergamon Journals Ltd.