Bibliography of the Maurice Lamontagne Institute

Lise BÉRARD-THERRIAULT

POULIN, M., N. LUNDHOLM, L. BÉRARD-THERRIAULT, M. STARR, R. GAGNON, 2010. Morphological and phylogenetic comparisons of Neodenticula seminae (bacillariophyta) populations between the subarctic Pacific and the Gulf of St. Lawrence. Eur. J. Phycol., 45(2): 127-142 .

Neodenticula seminae is a very important member of modern diatom assemblages in the Bering Sea and at middle to high latitudes of the North Pacific. In the North Atlantic, this species was considered extinct until it was recorded in high abundance in the 2001 spring phytoplankton bloom of the Gulf of St. Lawrence, Eastern Canada. Here, we discuss some of the most distinctive features of its morphology, including variation in some characters between the subarctic Pacific and the Gulf of St. Lawrence specimens. Most importantly, we observed that the deck and basal ridges, and the solid-walled costae (formerly known as primary pseudosepta) characteristic of N. seminae were present in the subarctic Pacific material, but were absent or vestigial in the Gulf of St. Lawrence material and in cultures from both regions. This morphological variation was most likely due to differences in physico–chemical water properties between the subarctic Pacific and the Gulf of St. Lawrence. Phylogenetic analyses of the internal transcribed spacer regions of the nuclear ribosomal DNA showed that the strains of N. Seminae collected in the Gulf of St. Lawrence and the subarctic Pacific clustered in two sister clades, but differed from each other only slightly more than the variation among the subarctic Pacific strains. These results confirmed the reappearance of N. Seminae in the NW Atlantic after an absence of ˜0.8 Ma. In addition, the phylogenetic analyses based on the large subunit of the nuclear ribosomal DNA positioned N. seminae firmly within the Bacillariaceae (i.e. diatoms with a fibulate raphe system) and proved a close relationship to species of Fragilariopsis.©2010 British Phycological Society

STARR, M., L. ST-AMAND, L. DEVINE, L. BÉRARD-THERRIAULT, P.S. GALBRAITH, 2004. State of phytoplankton in the Estuary and Gulf of St. Lawrence during 2003 ; État du phytoplancton dans l’estuaire et le golfe du Saint-Laurent en 2003. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2004/123, 35 p .

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We reviewed information concerning the seasonal and interannual variations in the concentrations of chlorophyll a, nitrates, and silicates as well as the abundance of the major species of phytoplankton measured at three fixed stations (Rimouski, Anticosti Gyre, and Gaspé Current) and six sections crossing the Estuary and Gulf of St. Lawrence. We concentrated on conditions prevailing in 2003 but also compared those observations with previous information from the 1992-2002 period. In 2003, the initiation of the major phytoplankton bloom at Station Rimouski in the Lower St. Lawrence Estuary occurred in late May, which is one month earlier than usual. Excluding 2002, this continued a trend that began in 1998. This major shift in the timing of the phytoplankton cycle is believed to be due to the below-normal spring freshwater runoff that has been generally observed in the St. Lawrence basin since 1998. The average phytoplankton biomass during spring-summer 2003 at Station Rimouski was also higher compared to 1992-1994, 1996, 1998, and 2000-2002, but lower compared to 1995, 1997, and, more especially, to 1999. Spring-summer phytoplankton production measured at this station was also much higher in 2003 compared to the previous three years but lower than in 1999. At the Anticosti Gyre and the Gaspé Current stations, nitrate and silicate concentrations were high in late fall-winter and low in late spring-summer due to biological consumption by phytoplankton. For both stations, the reduction of nutrients in the surface layer during spring-summer was much more pronounced in 2003 compared to the 2000-2002 period. Thus based on the evolution of nutrients, phytoplankton production in the northwestern Gulf of St. Lawrence could have been higher in 2003 compared to the previous three years. This is consistent with data from Station Rimouski in the Lower St. Lawrence Estuary. Similarly, the surface nutrient levels in late winter 2003 were also higher in the southern and northeastern Gulf of St. Lawrence compared to the previous two years while levels were not markedly different for the late spring-summer period. This suggests again that the spring phytoplankton bloom in these regions was also more intense in 2003 compared to recent years. For a third consecutive year, the analysis of the phytoplankton community composition in 2003 revealed the presence of the diatom Neodenticula seminae in many areas of the Gulf of St. Lawrence, with concentrations up to 197 X 10² cells per litre. This phenomenon is unusual since this species is typically found in North Pacific waters. In the Atlantic Ocean, this species has only been recorded in middle to high latitude Quaternary sediments, dating from between 0.84 and 1.2 million years ago. It is proposed that this Pacific species was introduced naturally into the Gulf (across the Arctic, down the Labrador Current, and through Strait of Belle Isle) rather than via ballast waters. The invasion of N. seminae on the Atlantic coast is consistent with recent observations suggesting a greater influx of Pacific waters into the Atlantic.

STARR, M., L. ST-AMAND, L. DEVINE, L. BÉRARD-THERRIAULT, 2003. State of phytoplankton in the Estuary and Gulf of St. Lawrence during 2002 ; État du phytoplancton dans l'estuaire et le golfe du St-Laurent en 2002. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2003/103, 29 p .

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Information concerning the seasonal and interannual variations in the concentrations of chlorophyll a, nitrates, and silicates as well as the abundance of the major species of phytoplankton measured from three fixed stations (Rimouski, Anticosti Gyre and Gaspé Current) and six sections crossing the Estuary and Gulf of St. Lawrence was reviewed. The authors concentrated on conditions prevailing in 2002 but also compared those observations with previous information from the 1992-2001 period. In 2002, the initiation of the major phytoplankton bloom at Station Rimouski in the Lower St. Lawrence Estuary occurred in late June, which is near the historical mean date. This contrasts with observations made from 1998 to 2001, when the spring phytoplankton bloom began 6-8 weeks earlier than normal (mid to early May). The average phytoplankton biomass during spring-summer 2002 at Station Rimouski was also somewhat higher compared to 1992-1994, 1998, and 2000-2001, but much lower compared to 1995, 1997, and, more especially, to 1999. In the Anticosti Gyre and the Gaspé Current, the depletion of nutrients in the surface layer (0-50 m) during spring occurred later in 2002 compared to the 1996-2001 period, suggesting that phytoplankton growth was also initiated later in 2002 compared to recent years in the northwestern part of the Gulf of St. Lawrence. This was particularly true for the Gaspé Current. The reduction of nutrients in the surface layer during spring-summer was also somewhat more pronounced in 2002 compared to the 2000-2001 period but much less compared to 1999. Thus based on the evolution of nutrients, phytoplankton production in the northwestern Gulf of St. Lawrence could have been higher in 2002 compared to the previous two years but much lower than for 1999. This is consistent with data from Station Rimouski in the Lower St. Lawrence Estuary. For a second consecutive year, the analysis of community composition in 2002 revealed the massive presence of the diatom Neodenticula seminae in most areas of the Gulf of St. Lawrence, with concentrations up to 1 x 106 cells per litre. This phenomenon is unusual since this species is usually found in North Pacific waters. In the Atlantic Ocean, this species has only been recorded in middle to high latitude Quaternary sediments, dating from between 0.84 and 1.2 million years ago. It is proposed that this Pacific species was introduced naturally into the Gulf (across the Arctic, down the Labrador Current, and through Strait of Belle Isle) rather than via ballast waters. The return of N. seminae to the Atlantic coast is consistent with recent observations indicating a greater influx of Pacific waters into the Atlantic and the freshening of the North Atlantic waters. In late spring and early fall 2002, the chlorophyll levels were higher in the southern Gulf of St. Lawrence compared to the previous three years. In the eastern part of the Gulf, the chlorophyll and nitrate levels in the surface layer in late spring and fall 2002 were not notably different from those observed in 1999-2001.

STARR, M., L. ST-AMAND, L. BÉRARD-THERRIAULT, 2002. State of phytoplankton in the Estuary and Gulf of St. Lawrence during 2001 ; État de phytoplancton dans l'estuaire et le golfe du Saint-Laurent en 2001. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2002/067, 23 p .

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We review the information concerning the seasonal and interannual variations in the concentrations of chlorophyll a, nitrates, and silicates as well as the abundance of the major species of phytoplankton measured from three fixed stations and six sections crossing the Estuary and Gulf of St. Lawrence. We focus on the conditions prevailing in 2001 but compare those observations with previous information from the period of 1992-2000. In 2001, the initiation of the spring phytoplankton bloom at Station Rimouski in the Lower St. Lawrence Estuary occurred in early May, that is, 6-8 weeks earlier than usual. This continued a trend that began in 1998. This major shift in the timing of the phytoplankton cycle is believed to be due to the below-normal spring freshwater runoff observed in the St. Lawrence basin since 1998. For the second consecutive year, the average phytoplankton biomass at Station Rimouski during spring-summer 2001 was much lower compared to the 1995-1999 period (except for 1998) but comparable to the 1992-1994 period. In particular, the phytoplankton biomass in July 2001 was much lower compared to our previous observations. This is believed to be due to a more intense mixing period in the Lower St. Lawrence Estuary in July 2001. In the Anticosti Gyre and the Gaspé Current, the reduction of nutrients in the surface layer during spring-summer-fall 2001 was much less pronounced compared to the 1996-1999 period (except for 1998). In the Gaspé Current, near-surface chlorophyll levels were also generally lower in 2001 compared to the previous two years. On the other hand, summertime chlorophyll levels in the Anticosti Gyre were higher in 2001 compared to those observed in 1997-2000. Satellite observations of sea surface chlorophyll concentrations indicate that the 2001 spring bloom occurred in late April for most areas of the Gulf of St. Lawrence. This contrasts with previous observations showing a greater spatial variability in the timing of the bloom. The analysis of community composition showed that the 2001 spring bloom over most of the Gulf was principally dominated by the diatom Neodenticula seminae. This is the first occurrence of this species in the Gulf of St. Lawrence; this species is usually found in North Pacific waters. This unusual event is consistent with recent observations indicating a greater influx of Pacific waters into the Atlantic Ocean (via the Bering Strait) and with hydrographic evidence of a major intrusion of Labrador Slope Water into the Gulf of St. Lawrence in 2001. In late spring 2001, the chlorophyll levels were extremely low for most areas of the Gulf of St. Lawrence. The highest levels were observed in the nutrient-rich waters of the St. Lawrence Estuary and Gaspé Current system. In the eastern and southern part of the Gulf, the chlorophyll and nitrate levels in the surface layer in late spring 2001 were not notably different than those observed in 1999-2000.

BÉRARD-THERRIAULT, L., M. POULIN, L. BOSSÉ, 1999. Guide d'identification du phytoplancton marin de l'estuaire et du golfe du Saint-Laurent incluant également certains protozoaires. Conseil national de recherches du Canada (Publ. spéc. can. sci. halieut. aquat., 128), 387 p .

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 .

SMITH, J.C., N. BOUCHARD-STEEVES, D. BLASCO, M. LEMAY, A. GERVAIS, R. GELINAS, S. GOSSELIN, B. HUPPERTZ, P. KEIZER, C.M. YENTSCH; C. POWELL, S. HANCOCK, K.H. MANN, J. MARTIN, L. BÉRARD-THERRIAULT, J.-C. THERRIAULT, E. BERDALET, 1992. Monitoring toward year 2000. Pages 91-104 in J.-C. Therriault & M. Levasseur (ed.). Proceedings of the Third Canadian Workshop on Harmful Marine Algae, Maurice-Lamontagne lnstitute, Mont-Joli, Québec, 12-14 May, 1992 .

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