Phytoplankton productivity on the Canadian Shelf of the Beaufort Sea

Carmack, Eddy C.; Macdonald, R. W.; Jasper, Steve

doi:10.3354/meps277037

Cited by 247 publications

(233 citation statements)

References 32 publications

(40 reference statements)

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“…The physical and geochemical oceanography of this region is well documented (Carmack & Macdonald 2002), and several reports exist concerning the upper trophic levels (Dickson & Gilchrist 2002, Harwood & Smith 2002, Stirling 2002. Many studies have examined the phytoplankton and zooplankton (Carmack et al 2004 and references therein), but few have considered microbial communities and processes, and this lack of microbiological information has been identified as a major gap in understanding the structure and dynamics of this coastal arctic ecosystem (Amon 2004). Early studies of the microbiota were conducted in the western Beaufort Sea, at nearshore sites off Alaska, and were based on observations of bacterial isolates brought into culture (Kaneko et al 1977(Kaneko et al , 1978a.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

“…In the western Canadian Arctic, the Mackenzie River discharges large quantities of freshwater, solutes and sediments into a vast shelf region of the Beaufort Sea that extends >100 km offshore and encompasses a total area of 63 600 km 2 (Carmack et al 2004). The annual discharge of the Mackenzie River (330 km 3 yr -1 ; Macdonald et al 1998) is the 4th highest in the Arctic Basin after the Siberian rivers Yenisei, Lena and Ob, with concomitantly large inputs of freshwater biota, terrestrial nutrients, organic carbon and suspended sediment.…”

Section: Introductionmentioning

confidence: 99%

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Prokaryotic community structure and heterotrophic production in a river-influenced coastal arctic ecosystem

Garneau

Vincent²,

Alonso‐Sáez³

et al. 2006

Aquat. Microb. Ecol.

130

105

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Spatial patterns in prokaryotic biodiversity and production were assessed in the Mackenzie shelf region of the Beaufort Sea during open-water conditions. The sampling transect extended 350 km northwards, from upstream freshwater sites in the Mackenzie River to coastal and offshore sites, towards the edge of the perennial arctic ice pack. The analyses revealed strong gradients in community structure and prokaryotic cell concentrations, both of which correlated with salinity. Picocyanobacterial abundance was low (10 2 to 10 3 cells ml -1 ), particularly at the offshore stations that were least influenced by the river plume. Analysis by catalyzed reporter deposition for fluorescence in situ hybridization (CARD-FISH) showed that the dominant heterotrophic cell types were β-Proteobacteria at river sites, shifting to dominance by α-Proteobacteria offshore. Cells in the Cytophaga-Flavobacter-Bacteroides and γ-Proteobacteria groups each contributed < 5% of total counts in the river, but >10% of counts in the marine samples. Archaea were detected among the surface-water microbiota, contributing on average 1.3% of the total DAPI counts in marine samples, but 6.0% in turbid coastal and riverine waters. 3 H-leucine uptake rates were significantly higher at 2 stations influenced by the river (1.5 pmol l -1 h -1 ) than at other marine stations or in the river itself (≤0.5 pmol -1 h -1 ). Size-fractionation experiments at 2 coastal sites showed that > 65% of heterotrophic production was associated with particles > 3 µm. These results indicate the importance of particleattached prokaryotes, and imply a broad functional diversity of heterotrophic microbes that likely facilitates breakdown of the heterogeneous dissolved and particulate terrestrial materials discharged into arctic seas. KEY WORDS:Prokaryote diversity · Archaea · Proteobacteria · Cytophaga-FlavobacterBacteroides · Arctic Ocean · Mackenzie River estuary · Picocyanobacteria · CARD-FISH Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 42: [27][28][29][30][31][32][33][34][35][36][37][38][39][40] 2006 ments (Payette et al. 2004) may mobilize the large stocks of organic carbon contained within their soils and cause increased transfer of these materials to arctic rivers and ultimately to the ocean. Heterotrophic microbiota are likely to play a major role in the response of coastal arctic ecosystems to ongoing change, but prokaryotic diversity and production in these cold ocean environments have been little explored (Amon 2004).In the western Canadian Arctic, the Mackenzie River discharges large quantities of freshwater, solutes and sediments into a vast shelf region of the Beaufort Sea that extends >100 km offshore and encompasses a total area of 63 600 km 2 (Carmack et al. 2004). The annual discharge of the Mackenzie River (330 km 3 yr -1 ; Macdonald et al. 1998) is the 4th highest in the Arctic Basin after the Siberian rivers Yenisei, Lena and Ob, with concomitantly large inputs of freshwater biota, terrestria...

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Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Prokaryotic community structure and heterotrophic production in a river-influenced coastal arctic ecosystem

Garneau

Vincent²,

Alonso‐Sáez³

et al. 2006

Aquat. Microb. Ecol.

130

105

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“…Relationships between PAR (E; estimated with a Biospherical QSL-2101 light sensor) and the uptake of C and N by phytoplankton from the SCM were assessed in four, ten-position light-gradient incubators designed to minimize spectral shift and accurately resolve photosynthetic parameters, especially in oligotrophic waters (Babin et al, 1994). Full-spectrum, 400-W Optimarc metal-halide lamps mimicking solar irradiance were used in combination with a blue filter (118 Light Blue Lee Filters Ltd.) and optically neutral filters (Lee Filters) to simulate the coastal underwater light spectrum (Hill and Cota, 2005;Carmack et al, 2004;Harrison et al, 1977). Actual PAR values in the incubators were kept in the low range to reproduce conditions near the SCM (from 664.2 to 0.3 µmol quanta −1 m −2 s −1 in 2005, with 6 of the 10 light intensities below 100 µmol quanta m −2 s −1 and from 309.1 to 1.8 µmol quanta −1 m −2 s −1 in 2006, 358.0 to 3.0 µmol quanta −1 m −2 s −1 in 2007 and 281.0 to 1.8 µmol quanta −1 m −2 s −1 in 2008, with 8 or 9 of the 10 light intensities below 100 µmol quanta m −2 s −1 ).…”

Section: Incubationsmentioning

confidence: 99%

Nutritive and photosynthetic ecology of subsurface chlorophyll maxima in Canadian Arctic waters

Martin¹,

Tremblay²,

Price

2012

Biogeosciences

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Abstract. Assessments of carbon and nitrogen (N) assimilation in Canadian Arctic waters confirmed the large contribution of subsurface chlorophyll maxima (SCM) to total water-column production from spring to late fall. Although SCM communities showed acclimation to low irradiance and greater nitrate (NO − 3 ) availability, their productivity was generally constrained by light and temperature. During springearly summer, most of the primary production at the SCM was sustained by NO − 3 , with an average f -ratio (i.e., relative contribution of NO − 3 uptake to total N uptake) of 0.74 ± 0.26. The seasonal decrease in NO − 3 availability and irradiance, coupled to the build up of ammonium (NH + 4 ), favoured a transition toward a predominantly regenerative system (fratio = 0.37 ± 0.20) during late summer and fall. Results emphasize the need to adequately consider SCM when estimating primary production and to revisit ecosystem model parameters in highly stratified Arctic waters.

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“…There it mixes with the outXow of the Mackenzie River, which generally also Xows eastward and spreads out across the Mackenzie Shelf (also called the Canadian Shelf). Between roughly mid-May to November, freshwater Xow from the river-the Mackenzie plume-dominates the Xow over the Mackenzie Shelf in a highly turbid surface layer about 5 m thick that overlays a brackish mixed layer from ice melt that extends to about 10-15 m (Carmack et al 2004). The plume predominantly Xows eastward into the Amundsen Gulf; its westward extent is unknown (Dunton et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Water mass and bathymetric characteristics of polar cod habitat along the continental shelf and slope of the Beaufort and Chukchi seas

2011

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Relatively little is known about the distribution of Wsh in deep water (>200 m) in the Beaufort Sea. Data collected by an Acoustic Doppler Current ProWler operated in the Chukchi and Beaufort seas in summer were examined for evidence of Wsh biomass detections between 18 and 400 m. The presence of Wsh in waters between 1 and 30 m was explored opportunistically with a non-scientiWc echo sounder. Evaluation of Wndings was enhanced by measurements of water column properties (temperature, salinity, Xuorescence and transmissivity). Relatively small shoals of Wsh were detected on the Chukchi shelf and eastern Chukchi shelf break, and also on the Alaskan and Canadian Beaufort shelves in the upper 20 m (T = 2-5°C). Much larger shoals (putative polar cod) were detected within Atlantic Water along the Beaufort continental slope (250-350 m) and near the bottom of Barrow and Mackenzie canyons, where temperatures were above 0°C. A warm-water plume of Alaska Coastal Current water with high concentrations of phytoplankton, zooplankton, and Wsh was found extending along the shelf 300 km eastward of Barrow Canyon. In contrast to the warm surface and Atlantic Water layers, very few Wsh were found in colder, intermediate depth PaciWc-origin water between them. The large biomass of Wsh in the Atlantic Water along the continental slope of the Chukchi and Beaufort seas represents previously undescribed polar cod habitat. It has important implications with regard to considerations of resource development in this area as well as understanding impacts of climate change.

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Phytoplankton productivity on the Canadian Shelf of the Beaufort Sea

Cited by 247 publications

References 32 publications

Prokaryotic community structure and heterotrophic production in a river-influenced coastal arctic ecosystem

Prokaryotic community structure and heterotrophic production in a river-influenced coastal arctic ecosystem

Nutritive and photosynthetic ecology of subsurface chlorophyll maxima in Canadian Arctic waters

Water mass and bathymetric characteristics of polar cod habitat along the continental shelf and slope of the Beaufort and Chukchi seas

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