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Bibliography of the Maurice Lamontagne Institute

Sylvie O. ROY

SCARRATT, M.G., M. LEVASSEUR, S. MICHAUD, S. ROY, 2007. DMSP and DMS in the Northwest Atlantic: late-summer distributions, production rates and sea-air fluxes. Aquat. Sci., 69(3): 292-304 .

DMSP and DMS were measured along a set of transects in the Northwest Atlantic during September, 1999. Six 24 h Lagrangian stations were occupied between 36° and 61° N latitude, covering subtropical to polar water types. Profiles of total DMSP (DMSPt), DMS, chl a, and oceanographic variables were determined at each station. Phytoplankton abundance and species assemblage were determined in surface waters and at the depth of the Chl a maximum in all profiles. Between profile stations, DMSPt and DMS samples were collected by a pump while the vessel was moving. Chl a and DMSPt were most abundant in the northern regions, with very low levels in subtropical waters. There was no direct correlation between DMSP t and Chl a. Maximum DMSPt concentrations reached 203 nM in coastal waters and 112 nM in the open ocean. A strong correlation was observed between DMSPt and the abundance of dinoflagellates (Spearman r=0.91; p <0.0001; n=13) and prymnesiophytes (Spearman r=0.91; p<0.0001; n=13). Cryptophytes also showed a weak but significant correlation (Spearman r=0.58; p=0.039; n=13). The waters around Greenland were the only site dominated by diatoms and their abundance was not correlated with DMSPt concentrations. DMS concentrations were low and fairly uniform, with maximum levels of 4.7 nM in coastal waters and 2.2 nM in the open ocean. DMS fluxes from surface waters were calculated based on observed sea-surface concentrations and wind speeds and showed a strong peak associated with a storm event, although no depletion of DMS resulting from the storm was observed. In situ incubation experiments showed DMSP consumption and DMS production rates to be relatively high, notwithstanding the generally low phytoplankton biomass.©2007 Eawag, Dübendorf

LEVASSEUR, M., M. SCARRATT, S. ROY, D. LAROCHE, S. MICHAUD, G. CANTIN, M. GOSSELIN, A. VÉZINA, 2004. Vertically resolved cycling of dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) in the Northwest Atlantic in spring. Can. J. Fish. Aquat. Sci., 61: 744-757 .

In May 1998, profiles of ambient concentration and net changes of particulate dimethylsulfoniopropionate (DMSPp), dissolved dimethylsulfoniopropionate (DMSPd), and dimethylsulfide (DMS) were measured in three bio geographic provinces of the Northwest Atlantic: Northwest Atlantic Continental Shelf (Grand Banks), North Atlantic Drift, and North Atlantic Subtropical Gyre (Sargasso Sea). All stations/depths exhibited large losses of DMSPp (up to 18.0 nmol·L-1·day-1). DMSP and DMS cycling varied in relation to the type and development stage of the plankton assemblages. The postdiatom bloom conditions on the Grand Banks were associated with an efficient utilization of DMSP by microzooplankton and bacteria. Bacterial DMS production balanced the DMS bacterial consumption, resulting in little net DMS production (0.3 nmol·L-1·day-1). This contrasted with the North Atlantic Drift and Sargasso Sea stations where flagellates were thriving and most of the DMSPp loss was recovered in the dissolved pool, indicating a less active microbial DMSP metabolism. DMSPd cleavage was high in these latter cases and exceeded DMS bacterial consumption, allowing a net production of DMS (up to 1.8 nmol·L-1·day-1). These results indicate that maximum DMS net production occurs in growing algal systems where the production of DMSPd resulting from microzooplankton grazing exceeds the bacterial requirement in carbon and sulfur.©2004 NRC Canada

ROY, S.O., T.T. PACKARD, 2001. CO2 production rate predicted from isocitrate dehydrogenase activity, intracellular substate concentrations and kinetic constants in the marine bacterium Pseudomonas nautica. Mar. Biol., 138: 1251-1258 .

FAUCHOT, J., M. GOSSELIN, M. LEVASSEUR, B. MOSTAJIR, C. BELZILE, S. DEMERS, S. ROY, P.Z. VILLEGAS, 2000. Influence of UV-B radiation on nitrogen utilization by a natural assemblage of phytoplankton. J. Phycol., 36: 484-496 .

PACKARD, T., W. CHEN, D. BLASCO, C. SAVENKOFF, A.F. VEZINA, R. TIAN, L. ST-AMAND, S.O. ROY, C. LOVEJOY, B. KLEIN, J.-C. THERRIAULT, L. LEGENDRE, R.G. INGRAM, 2000. Dissolved organic carbon in the Gulf of St. Lawrence. Deep-Sea Res., Part II , Top. Stud. Oceanogr., 47(3-4): 435-459 .

ROY, S.O., PACKARD, T.T., BERDALET, E., ST-AMAND, L., 1999. Impact of acetate, pyruvate, and physiological state on respiration and respiratory quotients in Pseudomonas nautica. Aquat. Microbiol. Ecol., 17: 105-110 .

ROY, S.O., T.T. PACKARD, 1998. NADP-isocitrate dehydrogenase from Pseudomonas nautica : kinetic constant determination and carbon limitation effects on the pool of intracellular substrates. Appl. Environ. Microbiol., 64: 4958-4964 .

PACKARD, T.T., E. BERDALET, D. BLASCO, S.O. ROY, L. ST-AMAND, B. LAGACÉ, K. LEE, J.-P. GAGNÉ, 1996. Oxygen consumption in the marine bacterium Pseudomonas nautica predicted from ETS activity and bisubstrate enzyme kinetics. J. Plankton Res., 18: 1819-1835 .

PACKARD, T., E. BERDALET, D. BLASCO, S.O. ROY, L. ST-AMAND, B. LAGACÉ, K. LEE, J.-P. GAGNÉ, 1996. CO2 production predicted from isocitrate dehydrogenase activity and bisubstrate enzyme kinetics in the marine bacterium Pseudomonas nautica. Aquat. Microbiol. Ecol., 11: 11-19 .