Personne : Babin, Marcel
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Université Laval. Département de biologie
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- PublicationAccès librePotential for the production of carotenoids of interest in the polar diatom Fragilariopsis cylindrus(Basel : MDPI, 2022-07-29) Guérin, Sébastien; Raguénès, Laura; Croteau, Dany; Lavaud, Johann; Babin, MarcelCarotenoid xanthophyll pigments are receiving growing interest in various industrial fields due to their broad and diverse bioactive and health beneficial properties. Fucoxanthin (Fx) and the inter-convertible couple diadinoxanthin–diatoxanthin (Ddx+Dtx) are acknowledged as some of the most promising xanthophylls; they are mainly synthesized by diatoms (Bacillariophyta). While temperate strains of diatoms have been widely investigated, recent years showed a growing interest in using polar strains, which are better adapted to the natural growth conditions of Nordic countries. The aim of the present study was to explore the potential of the polar diatom Fragilariopsis cylindrus in producing Fx and Ddx+Dtx by means of the manipulation of the growth light climate (daylength, light intensity and spectrum) and temperature. We further compared its best capacity to the strongest xanthophyll production levels reported for temperate counterparts grown under comparable conditions. In our hands, the best growing conditions for F. cylindrus were a semicontinuous growth at 7 °C and under a 12 h light:12 h dark photoperiod of monochromatic blue light (445 nm) at a PUR of 11.7 µmol photons m⁻² s⁻¹. This allowed the highest Fx productivity of 43.80 µg L⁻¹ day⁻¹ and the highest Fx yield of 7.53 µg Wh⁻¹, more than two times higher than under "white" light. For Ddx+Dtx, the highest productivity (4.55 µg L⁻¹ day⁻¹) was reached under the same conditions of "white light" and at 0 °C. Our results show that F. cylindrus, and potentially other polar diatom strains, are very well suited for Fx and Ddx+Dtx production under conditions of low temperature and light intensity, reaching similar productivity levels as model temperate counterparts such as Phaeodactylum tricornutum. The present work supports the possibility of using polar diatoms as an efficient cold and low light-adapted bioresource for xanthophyll pigments, especially usable in Nordic countries.
- PublicationAccès libreEstimating underwater light regime under spatially heterogeneous sea ice in the Arctic(2018-12-19) Bécu, Guislain; Massicotte, Philippe; Lambert Girard, Simon; Leymarie, Edouard; Babin, MarcelAbstract: The vertical diffuse attenuation coefficient for downward plane irradiance (Kd) is an apparent optical property commonly used in primary production models to propagate incident solar radiation in the water column. In open water, estimating Kd is relatively straightforward when a vertical profile of measurements of downward irradiance, Ed, is available. In the Arctic, the ice pack is characterized by a complex mosaic composed of sea ice with snow, ridges, melt ponds, and leads. Due to the resulting spatially heterogeneous light field in the top meters of the water column, it is difficult to measure at single-point locations meaningful Kd values that allow predicting average irradiance at any depth. The main objective of this work is to propose a new method to estimate average irradiance over large spatially heterogeneous area as it would be seen by drifting phytoplankton. Using both in situ data and 3D Monte Carlo numerical simulations of radiative transfer, we show that (1) the large-area average vertical profile of downward irradiance, Ed(z), under heterogeneous sea ice cover can be represented by a single-term exponential function and (2) the vertical attenuation coefficient for upward radiance (KLu), which is up to two times less influenced by a heterogeneous incident light field than Kd in the vicinity of a melt pond, can be used as a proxy to estimate Ed(z) in the water column.
- PublicationAccès libreA food web model for the Baffin Bay coastal and shelf ecosystem. Part 1 : Ecopath Technical Report(Elementa : science of the anthropocene, 2023-02-20) Pedro, Sara; Kenny, Tiff-Annie; Maps, Frédéric; Lemire, Mélanie; Saint-Béat, Blanche; Babin, Marcel; Tremblay, Jean-Éric; Yunda-Guarin, Gustavo; Moisan, Marie-Ange; Boissinot, Justin; Hoover, Carie; Janjua, Muhammad Yamin; Herbig, Jennifer; Geoffroy, Maxime; Little, Matthew; Chan, LaurieThis work was undertaken as part of a multidisciplinary research project funded by the Marine Observation Prediction and Assessment Network - MEOPAR (at ULaval), Canadian Institute of Health Research – CIHR (at University of Ottawa), and Sentinel North (at ULaval), and hosted at Université Laval, in Canada. The objective of the overall project is to support the food security (i.e., the availability and access to sufficient, safe, nutritious food that meets dietary preference) of Inuit communities of the Eastern Canadian Arctic, as well as to explore ways to adapt to effects of climate change. Inuit fish and hunt local marine species, from invertebrates to fish and marine mammals, which make a large part of their diet and are central to their food security. With temperatures increasing twice as fast as the global average and sea ice becoming thinner and forming later, climate change effects on the distribution and abundance of Arctic marine species are already taking place. To better understand the effects of climate change in important subsistence species, a multi-species model (Ecopath with Ecosim) will be used to inform the development of an integrated ecosystem assessment. The model will be used as a tool to co-create scenarios of ecosystem change with the community of Qikiqtarjuaq, Nunavut, to inform adaptation strategies regarding food security (e.g., potential of new fisheries in the region). This report describes the development of an Ecopath model of the Baffin Bay coastal and shelf ecosystem. The methodology, data used to construct the model, data gaps and limitations are described.
- PublicationRestreintTwo versions of short-term phytoplankton ecophysiology and taxonomic assemblages in the Arctic Ocean’s North Water (Canada, Greenland)(Oxford University Press, 2021-03-17) Lovejoy, Connie.; Lacour, Thomas; Royer, Sarah-Jeanne; Freyria, Nastasia J; Babin, Marcel; Joli, NathaliePhotosynthetic performance in open marine waters is determined by how well phytoplankton species are adapted to their immediate environment and available light. Although there is light for 24 h a day during the Arctic summer, little is known about short-term (h) temporal variability of phytoplankton photosynthetic performance in Arctic waters. To address this, we sampled the North Water (76.5°N) every 4 h over 24 h at two stations on the East and West sides that are influenced by different water masses and current conditions. We specifically investigated phytoplankton pigments, the xanthophyll cycle (XC), which is an indication of photoprotective capacity, and photosynthesis–irradiance (PE) response curves, at the surface and 20 m depth. The photophysiological parameters on the two sides differed along with the taxonomic signal derived from accessory pigments. On both sides, surface XC pigments showed high photoprotection capacity with the dinodinoxanthin–diatoxanthin (DD) and the violaxanthin, antheraxanthin and zeaxanthin cycles correlated with incoming radiation. The PE results showed that communities dominated by small flagellates on the western side performed better compared to diatom dominated communities on the eastern side. We conclude that phytoplankton and photosynthetic capacity differed consistent with known hydrography, with implications for a changing Arctic.
- PublicationAccès libreShifts in growth light optima among diatom species support their succession during the spring bloom in the Arctic(Cambridge : John Wiley & Sons Ltd, 2022-03-01) Lafond, Augustin; Croteau, Dany; Campbell, Douglas A. (Douglas Andrew),; Lacour, Thomas; Schiffrine, Nicolas; Morin, Philippe-Israël; Forget, Marie-Hélène; Bruyant, Flavienne; Ferland, Joannie; Tremblay, Jean-Éric; Lavaud, Johann; Babin, Marcel1. Diatoms of the Arctic Ocean annually experience extreme changes of light environment linked to photoperiodic cycles and seasonal variations of the snow and sea‐ice cover extent and thickness which attenuate light penetration in the water column. Arctic diatom communities exploit this complex seasonal dynamic through a well‐documented species succession during spring, beginning in sea‐ice and culminating in massive phytoplankton blooms underneath sea‐ice and in the marginal ice zone. The pattern of diatom taxa sequentially dominating this succession is relatively well conserved interannually, and taxonomic shifts seem to align with habitat transitions. 2. To understand whether differential photoadaptation strategies among diatom taxa explain these recurring succession sequences, we coupled lab experiments with field work in Baffin Bay at 67.5°N. Based on field data, we selected five diatom species typical of different ecological niches and measured their growth rates under light intensity ranges representative of their natural habitats. To characterize their photoacclimative responses, we sampled pigments and total particulate carbon, and conducted 14C‐uptake photosynthesis response curves and variable fluorescence measurements. 3. We documented a gradient in species respective light intensity for maximal growth suggesting divergent light response plasticity, which for the most part align with species sequential dominance. Other photophysiological parameters supported this ecophysiological framing, although contrasts were always clear only between succession endmembers, Nitzschia frigida and Chaetoceros neogracilis. To validate that these photoacclimative responses are representative of in situ dynamics, we compared them to the chlorophyll a‐specific light‐limited slope (α*) and saturated rate of photosynthesis (P*M), monitored in Baffin Bay on sea‐ice and planktonic communities. This complementary approach confirmed that unusual responses in α* and P*M as a function of light history intensity are similar between sentinel sympagic species N. frigida and natural ice‐core communities. While no light‐history‐dependent trends were observed in planktonic communities, their α* and P*M values were in the range of measurements from our monospecific cultures. 4. Synthesis. Our results suggest that Arctic diatoms species photoadaptation strategy is tuned to the light environment of the habitats in which they dominate and indeed drives the seasonal taxonomic succession.
- PublicationAccès libreSensitivity of phytoplankton primary production estimates to available irradiance under heterogeneous sea ice conditions(American Geophysical Union, 2019-06-30) Tremblay, Jean-Éric; Peeken, Ilka; Massicotte, Philippe; Katlein, Christian; Babin, Marcel; Flores, Hauke; Huot, Yannick; Castellani, Giulia; Arnd, Stefanie; Lange, B. (Benjamin)The Arctic ice scape is composed by a mosaic of ridges, hummocks, melt ponds, leads, and snow. Under such heterogeneous surfaces, drifting phytoplankton communities are experiencing a wide range of irradiance conditions and intensities that cannot be sampled representatively using single‐location measurements. Combining experimentally derived photosynthetic parameters with transmittance measurements acquired at spatial scales ranging from hundreds of meters (using a remotely operated vehicle, ROV) to thousands of meters (using a surface and underice trawl, SUIT), we assessed the sensitivity of water column primary production estimates to multiscale underice light measurements. Daily primary production calculated from transmittance from both the ROV and the SUIT ranged between 0.004 and 939 mgC·m−2·day−1. Upscaling these estimates at larger spatial scales using satellite‐derived sea ice concentration reduced the variability by 22% (0.004–731 mgC·m−2·day−1). The relative error in primary production estimates was two times lower when combining remote sensing and in situ data compared to ROV‐based estimates alone. These results suggest that spatially extensive in situ measurements must be combined with large‐footprint sea ice coverage sampling (e.g., remote sensing, aerial imagery) to accurately estimate primary production in ice‐covered waters. Also, the results indicated a decreasing error of primary production estimates with increasing sample size and the spatial scale at which in situ measurements are performed. Conversely, existing estimates of spatially integrated phytoplankton primary production in ice‐covered waters derived from single‐location light measurements may be associated with large statistical errors. Considering these implications is important for modeling scenarios and interpretation of existing measurements in a changing Arctic ecosystem.
- PublicationAccès libreContrasting nonphotochemical quenching patterns under high light and darkness aligns with light niche occupancy in Arctic diatoms(Wiley Online Library, 2020-09-02) Ferland, Joannie; Guérin, Sébastien; Croteau, Dany; Babin, Marcel; Bruyant, Flavienne; Campbell, Douglas A.; Lavaud, JohannOver the seasons, Arctic diatom species occupy shifting habitats defined by contrasting light climates, constrained by snow and ice cover dynamics interacting with extreme photoperiod and solar angle variations. How Arctic diatom photoadaptation strategies differ across their heterogeneous light niches remains a poorly documented but crucial missing link to anticipate Arctic Ocean responses to shrinking sea-ice and increasing light. To address this question, we selected five Arctic diatom species with diverse life traits, representative of distinct light niches across the seasonal light environment continuum: from snow-covered dimly lit bottom ice to summer stratified waters. We studied their photoacclimation plasticity to two growth light levels and the subsequent responses of their nonphotochemical quenching (NPQ) and xanthophyll cycle to both dark incubations and light shifts. We deciphered NPQ and xanthophyll cycle tuning in darkness and their light-dependent induction kinetics, which aligned with species' light niche occupancy. In ice-related species, NPQ was sustained in darkness and its induction was more reactive to moderate light shifts. Open-water species triggered strong NPQ induction in darkness and reached higher maximal NPQ under high light. Marginal ice zone species showed strong adaptation to light fluctuations with a dark response fine-tuned depending upon light history. We argue these traits are anchored in diverging photoadaption strategies fostering Arctic diatom success in their respective light niches.
- PublicationAccès libreGreen Edge ice camp campaigns : understanding the processes controlling the under-ice Arctic phytoplankton spring bloom(Göttingen Copernicus Publications, 2020-01-27) Massicotte, Philippe; Amiraux, Rémi; Amyot, Marie-Pier; Archambault, Philippe; Aubry, Cyril; Ayotte, Pierre; Bécu, Guislain; Bélanger, Simon; Bruyant, Flavienne; Christiansen-Stowe, Debra; Coupel, Pierre; Dezutter, Thibaud; Dominé, Florent; Dufour, Francis; Dufresne, Christiane; Dumont, Dany; Ferland, Joannie; Forget, Marie-Hélène; Fortier, Louis; Galí, Martí; Galindo, Virginie; Gourdal, Margaux; Grondin, Pierre-Luc; Guillot, Pascal; Guilmette, Caroline; Lacour, Léo; Lagunas, José Luis; Lalande, Catherine; Laliberté, Julien; Lambert Girard, Simon; Larivière, Jade; Lavaud, Johann; LeBaron, Anita; Lemire, Mélanie; Levasseur, Maurice; Marec, Claudie; Massé, Guillaume; Matsuoka, Atsushi; Neukermans, Griet; Oziel, Laurent; Rehm, Eric Carl; Reimer, Erin; Saint-Béat, Blanche; Sansoulet, Julie; Tremblay, Jean-Éric; Verin, Gauthier; Babin, MarcelThe Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797∘ N, 63.7895∘ W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea-ice cover from the surface to the bottom (at 360 m depth) to better understand the factors driving the PSB. Key variables, such as conservative temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured at the ice camp. Meteorological and snow-relevant variables were also monitored. Here, we present the results of a joint effort to tidy and standardize the collected datasets, which will facilitate their reuse in other Arctic studies.