Particulate organic carbon fluxes on the slope of the Mackenzie Shelf (Beaufort Sea): Physical and biological forcing of shelf-basin exchanges

Forest, Alexandre; Sampei, Makoto; Hattori, Hiroshi; Makabe, Ryosuke; Sasaki, Hiroshi; Fukuchi, Mitsuo; Wassmann, Paul; Fortier, Louis

doi:10.1016/j.jmarsys.2006.10.008

Cited by 125 publications

(124 citation statements)

References 47 publications

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“…sand, silt, clay) determine the faunal community. [197] To some degree, nearshore and shelf benthos take advantage of POC from riverine discharge in addition to the ice-associated primary productivity and grazer production). [125,198,199] Due to ice scouring, which occurs most prevalently at 10-to 50-m water depth in association with flaw leads, [14] faunal composition is patchy and continually undergoing community succession.…”

Section: Bottom Upmentioning

confidence: 99%

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

121

147

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Environmental context. Mercury, in its methylated form, is a neurotoxin that biomagnifies in marine and terrestrial foodwebs leading to elevated levels in fish and fish-eating mammals worldwide, including at numerous Arctic locations. Elevated mercury concentrations in Arctic country foods present a significant exposure risk to Arctic people. We present a detailed review of the fate of mercury in Arctic terrestrial and marine ecosystems, taking into account the extreme seasonality of Arctic ecosystems and the unique processes associated with sea ice and Arctic hydrology.Abstract. This review is the result of a series of multidisciplinary meetings organised by the Arctic Monitoring and Assessment Programme as part of their 2011 Assessment 'Mercury in the Arctic'. This paper presents the state-of-the-art knowledge on the environmental fate of mercury following its entry into the Arctic by oceanic, atmospheric and terrestrial pathways. Our focus is on the movement, transformation and bioaccumulation of Hg in aquatic (marine and fresh water) and terrestrial ecosystems. The processes most relevant to biological Hg uptake and the potential risk associated with Hg exposure in wildlife are emphasised. We present discussions of the chemical transformations of newly deposited or transported Hg in marine, fresh water and terrestrial environments and of the movement of Hg from air, soil and water environmental compartments into food webs. Methylation, a key process controlling the fate of Hg in most ecosystems, and the role of trophic processes in controlling Hg in higher order animals are also included. Case studies on Eastern Beaufort Sea beluga (Delphinapterus leucas) and landlocked Arctic char (Salvelinus alpinus) are presented as examples of the relationship between ecosystem trophic processes and biologic Hg levels. We examine whether atmospheric mercury depletion events (AMDEs) contribute to increased Hg levels in Arctic biota and provide information on the links between organic carbon and Hg speciation, dynamics and bioavailability. Long-term sequestration of Hg into non-biological archives is also addressed. The review concludes by identifying major knowledge gaps in our understanding, including:(1) the rates of Hg entry into marine and terrestrial ecosystems and the rates of inorganic and MeHg uptake by Arctic microbial and algal communities; (2) the bioavailable fraction of AMDE-related Hg and its rate of accumulation by biota and (3) the fresh water and marine MeHg cycle in the Arctic, especially the marine MeHg cycle.

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Section: Bottom Upmentioning

confidence: 99%

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

121

147

View full text Add to dashboard Cite

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“…Ardyna et al (2011) reported daily primary production rates of 159 ± 123 mg C m −2 d −1 in summer and fall, and intensive phytoplankton blooms related to ice-edge upwelling events were documented for coastal regions of the Mackenzie Shelf and Amundsen Gulf in 2008 (Mundy et al, 2009;Tremblay et al, 2011). An annual vertical POC flux of 1.6-1.8 g C m −2 yr −1 and 2.4 g C m −2 yr −1 was estimated at 200 m water depth for the Mackenzie Shelf and the Cape Bathurst polynya, respectively (Forest et al, 2007;Lalande et al, 2009;O'Brien et al, 2006). Seafloor sediments are dominated by fine-grained material that is usually composed of more than 70 % silt and clay (Conlan et al, 2008).…”

Section: Study Regionmentioning

confidence: 99%

“…As short-term scale we define seasonal to annual timescales and include the parameters sediment surface Chl a concentration and vertical POC export. Results reported from different seasons and years in the Beaufort Sea have shown that sediment Chl a concentration and vertical POC export vary both over seasons and years (Forest et al, 2007;Juul-Pedersen et al, 2010;Link et al, 2011;Morata et al, 2008;Renaud et al, 2007a;Sallon et al, 2011), respectively. This is due to the seasonal and spatial dynamics of primary production and carbon fluxes in the region (Forest et al, 2010;OrtegaRetuerta et al, 2012;Tremblay et al, 2011).…”

Section: Definition Of Short-term and Long-term Environmental Factorsmentioning

confidence: 99%

Multivariate benthic ecosystem functioning in the Arctic – benthic fluxes explained by environmental parameters in the southeastern Beaufort Sea

et al. 2013

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Abstract. The effects of climate change on Arctic marine ecosystems and their biogeochemical cycles are difficult to predict given the complex physical, biological and chemical interactions among the ecosystem components. We studied benthic biogeochemical fluxes in the Arctic and the influence of short-term (seasonal to annual), long-term (annual to decadal) and other environmental variability on their spatial distribution to provide a baseline for estimates of the impact of future changes. In summer 2009, we measured fluxes of dissolved oxygen, nitrate, nitrite, ammonia, soluble reactive phosphate and silicic acid at the sediment–water interface at eight sites in the southeastern Beaufort Sea at water depths from 45 to 580 m. The spatial pattern of the measured benthic boundary fluxes was heterogeneous. Multivariate analysis of flux data showed that no single or reduced combination of fluxes could explain the majority of spatial variation, indicating that oxygen flux is not representative of other nutrient sink–source dynamics. We tested the influence of eight environmental parameters on single benthic fluxes. Short-term environmental parameters (sinking flux of particulate organic carbon above the bottom, sediment surface Chl a) were most important for explaining oxygen, ammonium and nitrate fluxes. Long-term parameters (porosity, surface manganese and iron concentration, bottom water oxygen concentrations) together with δ13Corg signature explained most of the spatial variation in phosphate, nitrate and nitrite fluxes. Variation in pigments at the sediment surface was most important to explain variation in fluxes of silicic acid. In a model including all fluxes synchronously, the overall spatial distribution could be best explained (57%) by the combination of sediment Chl a, phaeopigments, δ13Corg, surficial manganese and bottom water oxygen concentration. We conclude that it is necessary to consider long-term environmental variability along with rapidly ongoing environmental changes to predict the flux of oxygen and nutrients across Arctic sediments even at short timescales. Our results contribute to improve ecological models predicting the impact of climate change on the functioning of marine ecosystems.

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“…The Mackenzie River is the largest river on the North American side of the Arctic with an annual freshwater discharge of 330 km 3 and an annual sediment load of 127 Mt to the Canadian Beaufort Shelf (Macdonald et al, 1998). Massive quantities of predominantly fine-grained sediment and associated organic carbon are transported into the Arctic Ocean during the freshet from May to September (Forest et al, 2007;Hill et al, 1991;Walker et al, 2008). Under the influence of the Coriolis force, this plume moves easterly, and sediments derived from coastal erosion on the seaward fringes of the estuary and Tuktoyaktuk Peninsula may be entrained in this system.…”

Section: Introductionmentioning

confidence: 99%

Geostatistical mapping and spatial variability of surficial sediment types on the Beaufort Shelf based on grain size data

Jerosch

2013

Journal of Marine Systems

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The paper describes an approach for a quality controlled mapping of grain sizes and sediment textures for the Beaufort Shelf in the Canadian Arctic. The approach is based on grain size data collected during the Nahidik Program (2005Program ( -2009 and earlier. A replenishment of grain size data since the 1980s, as well as the consideration of correlating parameters (bathymetry, slope and sediment input) to a cokriging algorithm, amends the former way of mapping the surficial sediments of the Beaufort Shelf. The cokriging analysis showed that the simulation of a sediment input by the Mackenzie River, modeled as a cost-distance function, was the key variable in reducing the errors of the output estimate. Furthermore, the approach compares the geostatistical interpolation methods of ordinary kriging and cokriging and recommends the use of a combination of both. The predicted mean standard errors showed that in this study cokriging was the superior interpolation method for clay, silt and sand while ordinary kriging was more suitable for gravel. A new sediment texture map, based on the grain size maps, is provided according to commonly used grain size and sediment type classification systems.

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Particulate organic carbon fluxes on the slope of the Mackenzie Shelf (Beaufort Sea): Physical and biological forcing of shelf-basin exchanges

Cited by 125 publications

References 47 publications

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Multivariate benthic ecosystem functioning in the Arctic – benthic fluxes explained by environmental parameters in the southeastern Beaufort Sea

Geostatistical mapping and spatial variability of surficial sediment types on the Beaufort Shelf based on grain size data

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