Michel Poulin

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Benthic diatoms bacillariophyta of hard substrates of salt and brackish waters of quebec 9. bacillariaceae

Phytoplankton biomass and production in the southeastern Beaufort Sea in autumn 2002 and 2003

Marine Ecology Progress Series, Feb 26, 2009

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Physical Control of Phytoplankton Production under Sea Ice (Manitounuk Sound, Hudson Bay)

Canadian Journal of Fisheries and Aquatic Sciences, Nov 1, 1981

In polar and subpolar seas, there are numerous accounts of phytoplankton blooms in the upper wate... more In polar and subpolar seas, there are numerous accounts of phytoplankton blooms in the upper water column under the ice. Various mechanisms have been invoked to explain these blooms: the seeding of the underlying surface water by algal cells (epontic flora) released from the melting ice, the optimization of light utilization by the cells, and the stabilization of the upper water column by the low-salinity melting water. From studies conducted in Manitounuk Sound (Hudson Bay), it is proposed that phytoplankton blooms under the ice probably result from the simultaneous deepening of both the photic layer (seasonal light increase) and the stratified layer (low-salinity melting water). In ice-covered seas, the release of ice algae superimposes itself on the phytoplankton bloom, resulting in the observed algal increase under melting ice.Key words: phytoplankton, under-ice blooms, ice flora, stability, nutrients, Hudson Bay

Sea ice diatoms from Manitounuk Sound, southeastern Hudson Bay (Quebec, Canada). I. Family Naviculaceae

Canadian journal of botany, Jul 1, 1982

The genus Navicula is the major constituent of the sea ice diatom community of Manitounuk Sound, ... more The genus Navicula is the major constituent of the sea ice diatom community of Manitounuk Sound, Hudson Bay. Taxonomical information is given for 43 taxa of the genus Navicula by means of complete illustrated descriptions. One new species and six varieties are described and a new combination is proposed.

Structures and Applications of Biomarkers from Arctic Sea Ice Diatoms

Encyclopedia of Quaternary Science, 2013

Polar oceans are characterized by the presence of seasonal and multiyear sea ice which can provid... more Polar oceans are characterized by the presence of seasonal and multiyear sea ice which can provide a habitat for autotrophic and heterotrophic organisms with diatoms dominating the bottom ice photosynthetic organisms. Sea ice diatoms produce a series of readily identifiable biomarker chemicals including fatty acids, sterols, and highly branched isoprenoid (HBI) alkenes. One monounsaturated HBI alkene, IP 25 , is specific to Arctic sea ice diatoms and its presence in underlying marine sediments has formed the basis of a proxy method for determining paleo-sea ice records.

Table 2) Dominant ice diatom species in samples obtained during a CCGS Amundsen cruise in 2008

Table 3) Fatty acid composition of ice algae sampled during a CCGS Amundsen cruise in 2008

$Research paper thumbnail of Table 6) Fatty acid composition of the polar lipid fraction of Calanus glacialis females obtained during a CCGS Amundsen cruise in 2008$

Table 6) Fatty acid composition of the polar lipid fraction of Calanus glacialis females obtained during a CCGS Amundsen cruise in 2008

Diatom abundance and fatty acid composition of ice algae and of Calanus glacialis in samples obtained in 2008 in the eastern Beaufort Sea

The copepod Calanus glacialis plays a key role in the lipid-based energy flux in Arctic shelf sea... more The copepod Calanus glacialis plays a key role in the lipid-based energy flux in Arctic shelf seas. By utilizing both ice algae and phytoplankton, this species is able to extend its growth season considerably in these seasonally ice-covered seas. This study investigated the impacts of the variability in timing and extent of the ice algal bloom on the reproduction and population success of C. glacialis. The vertical distribution, reproduction, amount of storage lipids, stable isotopes, fatty acid and fatty alcohol composition of C. glacialis were assessed during the Circumpolar Flaw Lead System Study. Data were collected in the Amundsen Gulf, south-eastern Beaufort Sea, from January to July 2008 with the core-sampling from March to April. The reduction in sea ice thickness and coverage observed in the Amundsen Gulf in 2007 and 2008 affected the life strategy and reproduction of C. glacialis. Developmental stages CIII and CIV dominated the overwintering population, which resulted in the presence of very few CV and females during spring 2008. Spawning began at the peak of the ice algal bloom that preceded the precocious May ice break-up. Although the main recruitment may have occurred later in the season, low abundance of females combined with a potential mismatch between egg production/development to the first feeding stage and phytoplankton bloom resulted in low recruitment of C. glacialis in the early summer of 2008.

$Research paper thumbnail of Table 5) Fatty acid and fatty alcohol composition of the neutral lipid fraction of Calanus glacialis females obtained during a CCGS Amundsen cruise in 2008$

Table 5) Fatty acid and fatty alcohol composition of the neutral lipid fraction of Calanus glacialis females obtained during a CCGS Amundsen cruise in 2008

(Table 4) Spawning frequency, egg production and clutch size of Calanus glacialis females obtained during a CCGS Amundsen cruise in 2008

Colonies of Gyrosigma eximium: a new phenomenon in Arctic tidal flats

Oceanologia, 2016

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1.3 Climate variability/change and marine ecosystem resources in Hudson Bay (Project 3.3)

The main objective of the project was to assess how climate-induced variability and change in sea... more The main objective of the project was to assess how climate-induced variability and change in sea temperature, sea ice cover dynamics and the timing and intensity of river freshet affect marine biological productivity, fish stocks and marine mammals in Hudson Bay. This chapter summarizes the scientific activities conducted from icebreakers and land-based laboratories and observations from space. Large spatial and temporal variability was observed in the physical, chemical, and biological data. River plumes influence primary production, phytoplankton taxonomic composition, zooplankton dynamics and the feeding success and survival of fish larvae in Hudson Bay’s immense estuarine system.

Biodiversity and Biogeography of the Lower Trophic Taxa of the Pacific Arctic Region: Sensitivities to Climate Change

The Pacific Arctic Region, 2014

ABSTRACT The lower trophic level taxa underpin the marine ecosystems of the Pacific Arctic Region... more ABSTRACT The lower trophic level taxa underpin the marine ecosystems of the Pacific Arctic Region (PAR). Recent field observations indicate that range shifts, and changes in the relative abundance of particular taxa have occurred within the last decade. Here we provide a region wide survey of the diversity and distribution of viruses, bacteria, archaea, auto- and heterotrophic protists, as well as metazoan zooplankton and benthic organisms in the PAR. Our aim is to provide a foundation for the assessment of the changes within the lower trophic level taxa of the PAR and to document such change when possible. Sensitivities to the effects of climate change are also discussed. Our vision is to enable data-based predictions regarding ecological succession in the PAR under current climate scenarios, and to deepen our understanding regarding what the future holds for higher trophic level organisms and the carbon cycle.

Characteristics of two distinct high-light acclimated algal communities during advanced stages of sea ice melt

Polar Biology, 2011

Biological characteristics of ice-associated algal communities were studied in Darnley Bay (weste... more Biological characteristics of ice-associated algal communities were studied in Darnley Bay (western Canadian Arctic) during a 2-week period in July 2008 when the landfast ice cover had reached an advanced stage of melt. We found two distinct and separate algal communities: (1) an interior ice community confined to brine channel networks beneath white ice covers; and (2) an ice melt water community in the brackish waters of both surface melt ponds and the layer immediately below the ice cover. Both communities reached maximum chlorophyll a concentrations of about 2.5 mg m -3 , but with diatoms dominating the interior ice while flagellates dominated the melt water community. The microflora of each community was diverse, containing both unique and shared algal species, the latter suggesting an initial seeding of the ice melt water by the bottom ice community. Absorption characteristics of the algae indicated the presence of mycosporine-like amino acids (MAAs) and carotenoid pigments as a photoprotective strategy against being confined to high-light near-surface layers. Although likely not contributing substantially to total annual primary production, these ice-associated communities may play an important ecological role in the Arctic marine ecosystem, supplying an accessible and stable food source to higher trophic levels during the period of ice melt.

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Temporal and vertical variations of lipid biomarkers during a bottom ice diatom bloom in the Canadian Beaufort Sea: further evidence for the use of the IP25 biomarker as a proxy for spring Arctic sea ice

Polar Biology, 2010

Variations in the concentrations of the sea ice diatom biomarker, IP 25 (Ice Proxy with 25 carbon... more Variations in the concentrations of the sea ice diatom biomarker, IP 25 (Ice Proxy with 25 carbon atoms), were measured in the bottom 10 cm of sea ice collected from the eastern Beaufort Sea and Amundsen Gulf from January to June 2008, as part of the International Polar Year-Circumpolar Flaw Lead system study. Temporal and vertical changes in IP 25 concentrations were compared against other biomarkers and indicators of ice algal production. IP 25 was not detected in sea ice samples collected from mid-winter to early spring, likely as a result of lightlimiting conditions for algal growth and accumulation. From early March to mid-June, IP 25 concentrations correlated well with those of fatty acids (r = 0.79; P \ 0.001), less so with total sterols (r = 0.63; P \ 0.001) and qualitatively with chlorophyll a concentrations and diatom cell abundances from adjacent sea ice cores. Approximately 90% of the total sea ice IP 25 accumulation occurred from mid-March to late-May, coincident with the ice algal bloom period. The majority (ca. 87-93%) of IP 25 was biosynthesised within the lower 5 cm of the sea ice where brine volume fractions were [5% which is consistent with the hypothesis that brine channel connectivity limits the internal colonisation of sea ice by diatoms. Maximum IP 25 concentrations occurred at 1-3 cm from the ice-water interface providing further evidence for a selective sea ice diatom origin for this biomarker. In contrast, vertical concentration profiles for fatty acids and sterols indicated mixed sources for these biomarkers.

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Protist assemblages in winter sea ice: setting the stage for the spring ice algal bloom

Polar Biology, 2011

This study documents, for the Wrst time, the abundance and species composition of protist assembl... more This study documents, for the Wrst time, the abundance and species composition of protist assemblages in Arctic sea ice during the dark winter period. Lack of knowledge of sea-ice assemblages during the dark period has left questions about the retention and survival of protist species that initiate the ice algal bloom. Sea-ice and surface water samples were collected between December 27, 2007 and January 31, 2008 within the Cape Bathurst Xaw lead, Canadian Beaufort Sea. Samples were analyzed for protist identiWcation and counts, chlorophyll (chl) a, and total particulate carbon and nitrogen concentrations. Sea-ice chl a concentrations (max. 0.27 g l ¡1) and total protist abundances (max. 4 £ 10 3 cells l ¡1) were very low, indicating minimal retention of protists in the ice during winter. The diversity of winter ice protists (134 taxa) was comparable to spring ice assemblages. Pennate diatoms dominated the winter protist assemblage numerically (averaging 77% of total protist abundances), with Nitzschia frigida being the most abundant species. Only 56 taxa were identiWed in surface waters, where dinoXagellates were the dominant group. Our results indicate that diVerences in the timing of ice formation may have a greater impact on the abundance than structure of protist assemblages present in winter sea ice and at the onset of the spring ice algal bloom.

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New criteria for species characterization in the genera Donkinia, Gyrosigma and Pleurosigma (Naviculaceae, Bacillariophyceae)

Phycologia, 1989

... 3) Cox 1979; (4) Cox 1983a; (5) Fabri & Leclercq 1984; (6) Gerloff & Helmcke 1977; (7... more

R�ponse d'une communaut� de diatom�es de glace � un gradient de salinit� (baie d'Hudson)

Marine Biology, 1983

Sea ice offers a physical support to the growth of microalgae (epontic community). Almost all the... more Sea ice offers a physical support to the growth of microalgae (epontic community). Almost all the studies on ice microflora in the Arctic and the Antarctic have been performed in waters of high salinities, and they generally reported a very high standing crop. From February through May 1978, 15 stations were sampled in the southeastern part of Hudson Bay (Manitounuk

Protists in Arctic drift and land‐fast sea ice

Journal of Phycology, 2013

Global climate change is having profound impacts on polar ice with changes in the duration and ex... more Global climate change is having profound impacts on polar ice with changes in the duration and extent of both land‐fast ice and drift ice, which is part of the polar ice pack. Sea ice is a distinct habitat and the morphologically identifiable sympagic community living within sea ice can be readily distinguished from pelagic species. Sympagic metazoa and diatoms have been studied extensively since they can be identified using microscopy techniques. However, non‐diatom eukaryotic cells living in ice have received much less attention despite taxa such as the dinoflagellate Polarella and the cercozoan Cryothecomonas being isolated from sea ice. Other small flagellates have also been reported, suggesting complex microbial food webs. Since smaller flagellates are fragile, often poorly preserved, and are difficult for non‐experts to identify, we applied high throughput tag sequencing of the V4 region of the 18S rRNA gene to investigate the eukaryotic microbiome within the ice. The sea ice ...

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