scholarly journals Upper Arctic Ocean water masses harbor distinct communities of heterotrophic flagellates

2013 ◽  
Vol 10 (6) ◽  
pp. 4273-4286 ◽  
Author(s):  
A. Monier ◽  
R. Terrado ◽  
M. Thaler ◽  
A. Comeau ◽  
E. Medrinal ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Water Column ◽  
Community Composition ◽  
Beaufort Sea ◽  
Water Masses ◽  
The Arctic ◽  
Heterotrophic Flagellates ◽  
Chlorophyll Maximum ◽  
Subsurface Chlorophyll Maximum ◽  
The Arctic Ocean

Abstract. The ubiquity of heterotrophic flagellates (HFL) in marine waters has been recognized for several decades, but the phylogenetic diversity of these small (ca. 0.8–20 μm cell diameter), mostly phagotrophic protists in the upper pelagic zone of the ocean is underappreciated. Community composition of microbes, including HFL, is the result of past and current environmental selection, and different taxa may be indicative of food webs that cycle carbon and energy very differently. While all oceanic water columns can be density stratified due to the temperature and salinity characteristics of different water masses, the Arctic Ocean is particularly well stratified, with nutrients often limiting in surface waters and most photosynthetic biomass confined to a subsurface chlorophyll maximum layer, where light and nutrients are both available. This physically well-characterized system provided an opportunity to explore the community diversity of HFL from different water masses within the water column. We used high-throughput DNA sequencing techniques as a rapid means of surveying the diversity of HFL communities in the southern Beaufort Sea (Canada), targeting the surface, the subsurface chlorophyll maximum layer (SCM) and just below the SCM. In addition to identifying major clades and their distribution, we explored the micro-diversity within the globally significant but uncultivated clade of marine stramenopiles (MAST-1) to examine the possibility of niche differentiation within the stratified water column. Our results strongly suggested that HFL community composition was determined by water mass rather than geographical location across the Beaufort Sea. Future work should focus on the biogeochemical and ecological repercussions of different HFL communities in the face of climate-driven changes to the physical structure of the Arctic Ocean.

scholarly journals Upper Arctic Ocean water masses harbor distinct communities of heterotrophic flagellates

2013 ◽  
Vol 10 (2) ◽  
pp. 3397-3430 ◽  
Author(s):  
A. Monier ◽  
R. Terrado ◽  
M. Thaler ◽  
A. M. Comeau ◽  
E. Medrinal ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Water Column ◽  
Community Composition ◽  
Beaufort Sea ◽  
Water Masses ◽  
Community Diversity ◽  
The Arctic ◽  
Heterotrophic Flagellates ◽  
Environmental Selection ◽  
The Arctic Ocean

Abstract. The ubiquity of heterotrophic flagellates (HFL) in marine waters has been recognized for several decades, but the phylogenetic diversity of these small (ca. 0.8–20 μm cell diameter), mostly phagotrophic protists in the pelagic zone of the ocean is underappreciated. Community composition of microbes, including HFL, is the result of past and current environmental selection, and different taxa may be indicative of food webs that cycle carbon and energy very differently. While all oceanic water columns can be density stratified due to the temperature and salinity characteristics of different water masses, the Arctic Ocean is particularly well stratified, with nutrients often limiting in surface waters and most photosynthetic biomass confined to a subsurface chlorophyll maximum (SCM) layer. This physically well-characterized system provided an opportunity to explore the community diversity of HFL across a wide region, and down the water column. We used high-throughput DNA sequencing techniques as a rapid means of surveying the diversity of HFL communities in the southern Beaufort Sea (Canada), targeting the surface, the SCM and just below the SCM. In addition to identifying major clades and their distribution, we explored the micro-diversity within the globally significant but uncultivated clade of marine stramenopiles (MAST-1) to examine the possibility of niche differentiation within the stratified water column. Our results strongly implied that HFL community composition was determined by water mass rather than geographical location across the Beaufort Sea. Future work should focus on the biogeochemical and ecological repercussions of different HFL communities in the face of climate driven changes to the physical structure of the Arctic Ocean.

scholarly journals Effects of Vertical Water Mass Segregation on Bacterial Community Structure in the Beaufort Sea

2019 ◽  
Vol 7 (10) ◽  
pp. 385
Author(s):  
Yunyun Fu ◽  
Richard B. Rivkin ◽  
Andrew S. Lang
Keyword(s):  
Bacterial Community ◽  
Sea Ice ◽  
Arctic Ocean ◽  
Community Composition ◽  
Bacterial Communities ◽  
Water Mass ◽  
Beaufort Sea ◽  
The Arctic ◽  
The Arctic Ocean ◽  
Mass Segregation

The Arctic Ocean is one of the least well-studied marine microbial ecosystems. Its low-temperature and low-salinity conditions are expected to result in distinct bacterial communities, in comparison to lower latitude oceans. However, this is an ocean currently in flux, with climate change exerting pronounced effects on sea-ice coverage and freshwater inputs. How such changes will affect this ecosystem are poorly constrained. In this study, we characterized the bacterial community compositions at different depths in both coastal, freshwater-influenced, and pelagic, sea-ice-covered locations in the Beaufort Sea in the western Canadian Arctic Ocean. The environmental factors controlling the bacterial community composition and diversity were investigated. Alphaproteobacteria dominated the bacterial communities in samples from all depths and stations. The Pelagibacterales and Rhodobacterales groups were the predominant taxonomic representatives within the Alphaproteobacteria. Bacterial communities in coastal and offshore samples differed significantly, and vertical water mass segregation was the controlling factor of community composition among the offshore samples, regardless of the taxonomic level considered. These data provide an important baseline view of the bacterial community in this ocean system that will be of value for future studies investigating possible changes in the Arctic Ocean in response to global change and/or anthropogenic disturbance.

Increasing Multiyear Sea Ice Loss in the Beaufort Sea: A New Export Pathway for the Diminishing Multiyear Ice Cover of the Arctic Ocean

2021 ◽  
Author(s):  
David Gareth Babb ◽  
Ryan J. Galley ◽  
Stephen E. L. Howell ◽  
Jack Christopher Landy ◽  
Julienne Christine Stroeve ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Beaufort Sea ◽  
Ice Cover ◽  
The Arctic ◽  
Export Pathway ◽  
The Arctic Ocean ◽  
Multiyear Ice

chapter 7 Carbon Export Efficiency and Phytoplankton Community Composition in the Atlantic Sector of the Arctic Ocean

2017 ◽  
pp. 149-188
Author(s):  
FRÉDÉRIC A. C. LE MOIGNE ◽  
ALEX J. POULTON ◽  
STEPHANIE A. HENSON ◽  
CHRIS J. DANIELS ◽  
GLAUCIA M. FRAGOSO ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Community Composition ◽  
Phytoplankton Community ◽  
The Arctic ◽  
Carbon Export ◽  
Atlantic Sector ◽  
Phytoplankton Community Composition ◽  
The Arctic Ocean

scholarly journals Modelling the effect of boundary scavenging on Thorium and Protactinium profiles in the ocean

2009 ◽  
Vol 6 (4) ◽  
pp. 7853-7896 ◽  
Author(s):  
M. Roy-Barman
Keyword(s):  
Arctic Ocean ◽  
Water Column ◽  
Open Ocean ◽  
The Arctic ◽  
Transport Parameters ◽  
Lateral Transport ◽  
Transport Reaction ◽  
The Pacific ◽  
The Arctic Ocean ◽  
Boundary Scavenging

Abstract. The "boundary scavenging" box model is a cornerstone of our understanding of the particle-reactive radionuclide fluxes between the open ocean and the ocean margins. However, it does not describe the radionuclide profiles in the water column. Here, I present the transport-reaction equations for radionuclides transported vertically by reversible scavenging on settling particles and laterally by horizontal currents between the margin and the open ocean. Analytical solutions of these equations are compared with existing data. In the Pacific Ocean, the model produces "almost" linear 230Th profiles (as observed in the data) despite lateral transport. However, omitting lateral transport biased the 230Th based particle flux estimates by as much as 50%. 231Pa profiles are well reproduced in the whole water column of the Pacific Margin and from the surface down to 3000 m in the Pacific subtropical gyre. Enhanced bottom scavenging or inflow of 231Pa-poor equatorial water may account for the model-data discrepancy below 3000 m. The lithogenic 232Th is modelled using the same transport parameters as 230Th but a different source function. The main source of 232Th scavenged in the open Pacific is advection from the ocean margin, whereas a net flux of 230Th produced in the open Pacific is advected and scavenged at the margin, illustrating boundary exchange. In the Arctic Ocean, the model reproduces 230Th measured profiles that the uni-dimensional scavenging model or the scavenging-ventilation model failed to explain. Moreover, if lateral transport is ignored, the 230Th based particle settling speed may by underestimated by a factor 4 at the Arctic Ocean margin. The very low scavenging rate in the open Arctic Ocean combined with the enhanced scavenging at the margin accounts for the lack of high 231Pa/230Th ratio in arctic sediments.

scholarly journals A 50 % increase in the mass of terrestrial particles delivered by the Mackenzie River into the Beaufort Sea (Canadian Arctic Ocean) over the last 10 years

2015 ◽  
Vol 12 (11) ◽  
pp. 3551-3565 ◽  
Author(s):  
D. Doxaran ◽  
E. Devred ◽  
M. Babin
Keyword(s):  
Organic Carbon ◽  
Arctic Ocean ◽  
Suspended Solids ◽  
Beaufort Sea ◽  
Freshwater Discharge ◽  
The Arctic ◽  
Field Observations ◽  
The Arctic Ocean ◽  
Arctic Rivers ◽  
Mackenzie River

Abstract. Global warming has a significant impact on the regional scale on the Arctic Ocean and surrounding coastal zones (i.e., Alaska, Canada, Greenland, Norway and Russia). The recent increase in air temperature has resulted in increased precipitation along the drainage basins of Arctic rivers. It has also directly impacted land and seawater temperatures with the consequence of melting permafrost and sea ice. An increase in freshwater discharge by main Arctic rivers has been clearly identified in time series of field observations. The freshwater discharge of the Mackenzie River has increased by 25% since 2003. This may have increased the mobilization and transport of various dissolved and particulate substances, including organic carbon, as well as their export to the ocean. The release from land to the ocean of such organic material, which has been sequestered in a frozen state since the Last Glacial Maximum, may significantly impact the Arctic Ocean carbon cycle as well as marine ecosystems. In this study we use 11 years of ocean color satellite data and field observations collected in 2009 to estimate the mass of terrestrial suspended solids and particulate organic carbon delivered by the Mackenzie River into the Beaufort Sea (Arctic Ocean). Our results show that during the summer period, the concentration of suspended solids at the river mouth, in the delta zone and in the river plume has increased by 46, 71 and 33%, respectively, since 2003. Combined with the variations observed in the freshwater discharge, this corresponds to a more than 50% increase in the particulate (terrestrial suspended particles and organic carbon) export from the Mackenzie River into the Beaufort Sea.

scholarly journals The Seasonal Variability of the Arctic Ocean Ekman Transport and Its Role in the Mixed Layer Heat and Salt Fluxes

2006 ◽  
Vol 19 (20) ◽  
pp. 5366-5387 ◽  
Author(s):  
Jiayan Yang
Keyword(s):  
Arctic Ocean ◽  
Mixed Layer ◽  
Seasonal Variability ◽  
Surface Wind ◽  
Beaufort Sea ◽  
Ekman Transport ◽  
The Arctic ◽  
Ekman Pumping ◽  
Basin Scale ◽  
The Arctic Ocean

Abstract The oceanic Ekman transport and pumping are among the most important parameters in studying the ocean general circulation and its variability. Upwelling due to the Ekman transport divergence has been identified as a leading mechanism for the seasonal to interannual variability of the upper-ocean heat content in many parts of the World Ocean, especially along coasts and the equator. Meanwhile, the Ekman pumping is the primary mechanism that drives basin-scale circulations in subtropical and subpolar oceans. In those ice-free oceans, the Ekman transport and pumping rate are calculated using the surface wind stress. In the ice-covered Arctic Ocean, the surface momentum flux comes from both air–water and ice–water stresses. The data required to compute these stresses are now available from satellite and buoy observations. But no basin-scale calculation of the Ekman transport in the Arctic Ocean has been done to date. In this study, a suite of satellite and buoy observations of ice motion, ice concentration, surface wind, etc., will be used to calculate the daily Ekman transport over the whole Arctic Ocean from 1978 to 2003 on a 25-km resolution. The seasonal variability and its relationship to the surface forcing fields will be examined. Meanwhile, the contribution of the Ekman transport to the seasonal fluxes of heat and salt to the Arctic Ocean mixed layer will be discussed. It was found that the greatest seasonal variations of Ekman transports of heat and salt occur in the southern Beaufort Sea in the fall and early winter when a strong anticyclonic wind and ice motion are present. The Ekman pumping velocity in the interior Beaufort Sea reaches as high as 10 cm day−1 in November while coastal upwelling is even stronger. The contributions of the Ekman transport to the heat and salt flux in the mixed layer are also considerable in the region.

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