Papers by Michel Gosselin
Marine Ecology Progress Series, 1997
~e v a s s e u r~, Sonia ~i c h a u d~, Patrick p on fort^, Serge ~e r n e r s~ 'Departement d'oc... more ~e v a s s e u r~, Sonia ~i c h a u d~, Patrick p on fort^, Serge ~e r n e r s~ 'Departement d'oceanographie, Universite d u Quebec a Rimouski,
Marine Ecology Progress Series, 1995
High resolution study of the platelet ice ecosystem in McMurdo Sound, Antarctica: biomass, nutrie... more High resolution study of the platelet ice ecosystem in McMurdo Sound, Antarctica: biomass, nutrient, and production profiles within a dense microalgal bloom Kevin R. ~rrigo'l*, Gerhard ~i e c k m a n n~, Michel ~o s s e l i n~, Dale H. ~o b i n s o n~, Christian H. ~r i t s e n~, Cornelius W. S~l l i v a n~~~
Marine Ecology Progress Series, 2015
Marine phytoplankton are known to produce mycosporine-like amino acids (MAAs) for protection agai... more Marine phytoplankton are known to produce mycosporine-like amino acids (MAAs) for protection against UV radiation. To assess whether the same strategy applies to sea ice-associated communities, MAAs were measured in algal communities associated with surface melt ponds, sea ice (bottom 3 cm), sea ice−water interface below melt ponds, and underlying seawater in a coastal bay of the Canadian Arctic Archipelago during the spring melt transition from snowcovered to melt pond-covered sea ice. Six UV-absorbing compounds (UVACs) were detected as the spring melt progressed, 3 of which are identified to be shinorine, palythine, and porphyra-334. A fourth UVAC (U1) is most likely palythene. The molecular identities of the other 2 UVACs, U2 and U3, which have an absorption maximum of 363 and 300 nm, respectively, remain to be structurally elucidated. The highest UVAC nominal concentrations were observed in the 3 cm bottom ice under thin snow-covered sites just prior to complete snowmelt. Normalization to chlorophyll a content revealed that the greatest contribution to UV absorption from biota was associated with melt ponds that are exposed to the highest light intensity. These results confirm that Arctic sea ice-associated communities are capable of producing photoprotectants and that spatial and temporal variations in MAA and other UVAC synthesis are affected by snow cover and UV radiation exposure.
Journal of Geophysical Research Oceans, 2014
[1] This study presents temporal variations in concentrations of chlorophyll a (Chl a), particula... more [1] This study presents temporal variations in concentrations of chlorophyll a (Chl a), particulate and dissolved dimethylsulfoniopropionate (DMSPp and DMSPd) in the sea ice and underlying water column in the Canadian Arctic Archipelago during the spring of 2010 and 2011. During both years, bottom-ice Chl a, DMSPp and DMSPd concentrations were high (up to 1328 µg L-1, 15 000 nmol L-1, and 6000 nmol L-1, respectively) in May and decreased thereafter. The release of bottom ice algae and DMSPp in the water column was gradual in 2010 and rapid (8 days) in 2011. Bottom brine drainage during the pre-snowmelt period in 2010 and a rapid loss of the snow cover in 2011 coinciding with rain events explain most of the difference between the two years. During both years, less than 13% of the DMSPd lost from the ice was detected in the water column, suggesting a rapid microbial consumption. An under-ice diatom bloom developed in both years. In 2010, the bloom was dominated by centric diatoms whil...
Progress in Oceanography, 2015
Marine ecosystems at high latitudes are characterized by extreme seasonal changes in light condit... more Marine ecosystems at high latitudes are characterized by extreme seasonal changes in light conditions, as well as a limited period of high primary production during spring and early summer. As light returns at the end of winter to Arctic ice-covered seas, a first algal bloom takes place in the bottom layer of the sea ice. This bottom ice algae community develops through three distinct phases in the transition from winter to spring, starting with phase I, a predominantly net heterotroph community that has limited interaction with the pelagic or benthic realms. Phase II begins in the spring once light for photosynthesis becomes available at the ice bottom, although interaction with the water column and benthos remains limited. The transition to the final phase III is then mainly driven by a balance of atmospheric and oceanographic forcing that induce structural changes in the sea ice and ultimately the removal of algal biomass from the ice. Due to limited data availability an incomplete understanding exists of all the processes determining ice algal bloom phenology and the considerable geographic differences in sympagic algal standing stocks and primary production. We present here the first pan-Arctic compilation of available time-series data on vernal sea ice algal bloom development and identify the most important factors controlling its development and termination. Using data from the area surrounding Resolute Bay (Nunavut, Canada) as an example, we support previous investigations that snow cover on top of the ice influences sea ice algal phenology, with highest biomass development, but also earliest termination of blooms, under low snow cover. We also provide a pan-Arctic overview of sea ice algae standing stocks and primary production, and discuss the pertinent processes behind the geographic differences we observed. Finally, we assess potential future changes in vernal algal bloom phenology as a consequence of climate change, including their importance to different groups of grazers.
Marine Ecology Progress Series, 2014
Marine Ecology Progress Series, 2000
The study investigates the planktonic food web of an oligotropluc atoll lagoon (Takapoto, French ... more The study investigates the planktonic food web of an oligotropluc atoll lagoon (Takapoto, French Polynesia). The growth (k) and grazing mortality (g) rates of heterotrophic bacteria, cyanobacteria, and 1-3 pm and >3 pm (large) algae were assessed, in the presence and absence of the large grazers (>35 pm protozoa), by serial dllution experiments. Taxa-specific feeding relationships were obtained from fluorescently labeled prey uptake experiments. The major consumers of 0.4 pm bacteria were aplastidic nanoflagellates (7 pm Leucocryptos and 10 pm Halosphaera), and those of 3-5 pm chlorophyceae (Nannochloropis and Chlarnydornonas) were heterotrophic dinoflagellates (32 pm Achradina and 33 pm Prorocentrum). The protozoa exerted a low grazing pressure on heterotrophic bacteria, even when the large grazers were removed (mean values: g = 0.26 d-'). In contrast, the grazing rates of 1200 pm protozoa on cyanobacteria (mean values. g = 0.43 d-l), which were the dominant pnmary producers, represented 74% of their growth rates. In absence of the >35 pm grazers, the grazing on cyanobacteria increased, being 4 times higher than on heterotrophic bacteria. These results indicate that, in an oligotrophic planktonic food web where the consumption of bacteria is low, the grazing of protozoa on cyanobacteria is a major carbon pathway. Large algae were grazed at rates equivalent to their growth rates (mean values: g = 0.47 d-'; k = 0.50 d-l), which implies a steady-state situation with rapid cycling of the algal biomass. In samples without the >35 pm grazers, the grazing mortality and growth rates of large phytoplankton increased significantly, indicating a close coupling between the growth of >3 pm algae and grazing pressure under natural conditions. This coupling is likely mediated by increased nutrient regeneration. The results indicate that the large protozoan consumers controlled the grazing pressure and nutrient regeneration of the small protozoa, which in turn controlled the abundance of phytoplankton and growth of large algae. It follows that the structure of the oligotrophic planktonic food web under low grazing on bacteria is ultimately governed by protozoan microzooplankton. KEY WORDS: Atoll lagoon. Coral reef. Planktonic food web. Protozoan grazing. Dilution method .
Marine Ecology Progress Series, 1993
Environmental control and potential fate of phytoplankton production were investigated in the Gre... more Environmental control and potential fate of phytoplankton production were investigated in the Greenland Sea (75" N) in June 1989. Phytoplankton biomass, taxonomic con~position and production were size fractionated. Total primary production was generally high (up to > 0.9 g C m-* d-'), especially in the Arctic Front. The production per unit biomass P B (z) was a nonlinear function of the vertical distribution of Irradiance E@), especially for the >5 pm fraction where E(z) accounted for 60 to 97 % of the variance of P B (z). Much of the subsurface chlorophyll was probably not photosynthetically active due to limitation by irradiance. There was a marked transition in several variables at the Arctic Front. To the west (Arctic Domain), waters were cooler and slightly less saline than to the east (Atlantic Domain), concentrations of silicate were lower, and total primary production was generally lower. The structure of phytoplankton assemblages (diatoms and dinoflagellates) changed at the front. Results confirmed the previously reported trend of a progressive decrease of phycoerythrin-containing cyanobacteria with increasing latitude. In the Arctic Domain, primary production was generally dominated by cells >5 pm, but this was not proportionally reflected in the standing stock which was dominated by the <5 pm fraction. This difference between production and standing stock was potentially due to strong grazing on the large cells. In the Arctic Front, production was equally shared by large and small cells, but the standing stock was still dominated by cells < 5 pm. Potential rates (i.e. calculated, not measured) of grazing and sedimentation of large versus small cells in the Arctic Front were lower than in the Arctic Domain. In the Atlantic Domain, both primary production and standing stock were largely dominated by cells < 5 pm.
Marine Ecology-progress Series, 1996
Jean-Pierre C h a n u t l q 3 , Michel ~o s s e l i n '~~, Telesphore Sime-Ngando4 'GREC (Groupe ... more Jean-Pierre C h a n u t l q 3 , Michel ~o s s e l i n '~~, Telesphore Sime-Ngando4 'GREC (Groupe de Recherche en Environnen~ent Cotier), 310 Allee des Ursulines,
Mar Ecol Prog Ser, 1996
Jean-Pierre C h a n u t l q 3 , Michel ~o s s e l i n '~~, Telesphore Sime-Ngando4 'GREC (Groupe ... more Jean-Pierre C h a n u t l q 3 , Michel ~o s s e l i n '~~, Telesphore Sime-Ngando4 'GREC (Groupe de Recherche en Environnen~ent Cotier), 310 Allee des Ursulines,
Biogeosciences, 2013
Predicting water-column phytoplankton biomass from near-surface measurements is a common approach... more Predicting water-column phytoplankton biomass from near-surface measurements is a common approach in biological oceanography, particularly since the advent of satellite remote sensing of ocean color (OC). In the Arctic Ocean, deep subsurface chlorophyll maxima (SCMs) that significantly contribute to primary production (PP) are often observed. These are neither detected by ocean color sensors nor accounted for in the primary production models applied to the Arctic Ocean. Here, we assemble a large database of pan-Arctic observations (i.e., 5206 stations) and develop an empirical model to estimate vertical chlorophyll a (Chl a) according to (1) the shelf-offshore gradient delimited by the 50 m isobath, (2) seasonal variability along pre-bloom, post-bloom, and winter periods, and (3) regional differences across ten sub-Arctic and Arctic seas. Our detailed analysis of the dataset shows that, for the pre-bloom and winter periods, as well as for high surface Chl a concentration (Chl a surf ; 0.7-30 mg m −3) throughout the open water period, the Chl a maximum is mainly located at or near the surface. Deep SCMs occur chiefly during the post-bloom period when Chl a surf is low (0-0.5 mg m −3). By applying our empirical model to annual Chl a surf time series, instead of the conventional method assuming vertically homogenous Chl a, we produce novel pan-Arctic PP estimates and associated uncertainties. Our results show that vertical variations in Chl a have a limited impact on annual depth-integrated PP. Small overestimates found when SCMs are shallow (i.e., pre-bloom, post-bloom > 0.7 mg m −3 , and the winter period) somehow compensate for the underestimates found when SCMs are deep (i.e., post-bloom < 0.5 mg m −3). SCMs are, however, important seasonal features with a substantial impact on depth-integrated PP estimates, especially when surface nitrate is exhausted in the Arctic Ocean and where highly stratified and oligotrophic conditions prevail.
Marine Ecology Progress Series, 2004
ABSTRACT: The downward export of organic material was assessed during the productive period (late... more ABSTRACT: The downward export of organic material was assessed during the productive period (late spring to early autumn) in the North Water polynya area (NOW; northern Baffin Bay). Freedrifting short-term particle interceptor traps were deployed at 3 depths below the ...
Proceedings of the National Academy of Sciences of the United States of America, Jun 30, 2017
Summertime Arctic shipboard observations of oxygenated volatile organic compounds (OVOCs) such as... more Summertime Arctic shipboard observations of oxygenated volatile organic compounds (OVOCs) such as organic acids, key precursors of climatically active secondary organic aerosol (SOA), are consistent with a novel source of OVOCs to the marine boundary layer via chemistry at the sea surface microlayer. Although this source has been studied in a laboratory setting, organic acid emissions from the sea surface microlayer have not previously been observed in ambient marine environments. Correlations between measurements of OVOCs, including high levels of formic acid, in the atmosphere (measured by an online high-resolution time-of-flight mass spectrometer) and dissolved organic matter in the ocean point to a marine source for the measured OVOCs. That this source is photomediated is indicated by correlations between the diurnal cycles of the OVOC measurements and solar radiation. In contrast, the OVOCs do not correlate with levels of isoprene, monoterpenes, or dimethyl sulfide. Results fro...
Marine Ecology Progress …, 2007
ABSTRACT: Newly formed sea ice was sampled at 32 stations on the Mackenzie shelf, between 30 Sept... more ABSTRACT: Newly formed sea ice was sampled at 32 stations on the Mackenzie shelf, between 30 September and 19 November 2003. At each station, sea ice and surface waters were analysed to assess the concentration and enrichment of nutrients, exopolymeric ...
Estuarine Coastal and Shelf Science, Aug 10, 2008
A steady-state model of the planktonic food web of the Bizerte Lagoon (Tunisia, South-western Med... more A steady-state model of the planktonic food web of the Bizerte Lagoon (Tunisia, South-western Mediterranean) was developed to characterize its structure and functioning through four stations: MA under urban discharge, MB impacted by industrial input, MJ located at ...
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Papers by Michel Gosselin