Influence of terrestrial organic matter in marine food webs of the Beaufort Sea shelf and slope

Bell, Lauren E.; Bluhm, Bodil A.; Iken, Katrin

doi:10.3354/meps11725

Cited by 71 publications

(72 citation statements)

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“…Due to the complexity of the lake-rich delta landscape, and the regular inputs of nutrients and sediments carried in flood and river water, the Mackenzie Delta is a hotspot of productivity and biodiversity in the circumpolar Arctic supporting large populations of birds, fish, and mammals and serves as a feeding and breeding ground for migratory birds (Squires et al 2009). Immediately offshore, nutrient-rich Mackenzie Delta discharge is incorporated into the productive marine food web on the Beaufort Shelf (Dunton et al 2006;Bell et al 2016), an important nursery for fish and marine mammal species. a Lake numbers that have been used to designate individual lakes in many prior studies of the Mackenzie River Delta.…”

Section: The Ecology and Hydrology Of The Mackenzie Deltamentioning

confidence: 99%

“…Heterotrophic grazers subsequently consume bacteria, which shunts otherwise unavailable carbon, organic matter, and energy back into the aquatic food web via the microbial loop (Azam et al 1983). This is a critical process that mobilizes otherwise unavailable DOM molecules in high-latitude aquatic environments (Cole 1999;Cory et al 2014) via bacteria, contributing to overall food web production in Mackenzie Delta lakes (Spears and Lesack 2006;Tank et al 2011), the Mackenzie River (Vallières et al 2008), and the nearshore Beaufort Sea (Garneau et al 2008;Bell et al 2016). Because DOM is an important component of carbon budgets in aquatic ecosystems, an understanding of how photodegradation alters DOM bioavailability is critical to understand carbon fluxes through the landscape.…”

Section: Introductionmentioning

confidence: 99%

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Photodegraded dissolved organic matter from peak freshet river discharge as a substrate for bacterial production in a lake-rich great Arctic delta

Gareis

Lesack

2018

Arctic Science

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Lake-rich Arctic river deltas are recharged with terrigenous dissolved organic matter (DOM) during the yearly peak water period corresponding with the solstice (24 h day −1 solar irradiance). Bacteria-free DOM collected during peak Mackenzie River discharge was exposed to sunlight for up to 14 days in June 2010. As solar exposure increased, carbon and lignin concentrations declined (10% and 42%, respectively, after 14 days), as did DOM absorptivity (62% after 14 days), aromaticity, and molecular weight. Photochemical changes were on par with those normally observed in Mackenzie Delta lakes over the entire open-water season. When irradiated freshet DOM was provided as a substrate, no significant differences were observed in community-level metabolism among five bacterial communities from representative delta habitats. However, bacterial abundance was significantly greater when nonirradiated (0 day) rather than irradiated DOM (7 or 14 days) was provided, while cell-specific metabolic measures revealed that per-cell bacterial production and growth efficiency were significantly greater when communities were provided irradiated substrate. This complex response to rapid DOM photodegradation may result from the production of inhibitory reactive oxygen species (ROS), along with shifts in bacterial community composition to species that are better able to tolerate ROS, or metabolize the labile photodegraded DOM.Key words: circumpolar river delta, photodegradation, dissolved organic matter, bacterial metabolism, Mackenzie River.Résumé : Les deltas arctiques riches en lacs sont rechargés en matière organique dissoute (MOD) terrigène pendant la période annuelle de crue maximale correspondant au solstice (irradiance solaire 24 h jour −1 ). De la MOD sans bactéries collectée durant la pointe de crue du fleuve Mackenzie a été exposée à la lumière du soleil pendant 14 jours en juin 2010. À mesure que l'exposition solaire se prolongeait, les concentrations de carbone et lignine diminuaient (10 % et 42 % respectivement, après 14 jours), tout comme le pouvoir d'absorption de la MOD (62 % après 14 jours), son aromaticité et son poids moléculaire. Les changements photochimiques correspondaient à ceux normalement observés dans les lacs du delta du Mackenzie sur l'ensemble de la saison des eaux libres. Lorsque de la MOD de crue irradiée fut utilisée comme substrat, aucune différence significative n'a été observée quant au métabolisme au niveau de la communauté en comparant cinq communautés bactériennes issues d'habitats représentatifs du delta. Néanmoins, l'abondance de bactéries était considérablement plus grande lorsque de la For personal use only.MOD non irradiée (0 jour) a été fournie au lieu de la MOD irradiée (7 ou 14 jours), tandis que les mesures de l'activité métabolique spécifique aux cellules ont révélé que la production bactérienne par cellule et le rendement de croissance étaient considér-ablement plus élevés lorsque les communautés avaient accès au substrat irradié. Cette réaction complexe à la photodégradation...

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Section: The Ecology and Hydrology Of The Mackenzie Deltamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photodegraded dissolved organic matter from peak freshet river discharge as a substrate for bacterial production in a lake-rich great Arctic delta

Gareis

Lesack

2018

Arctic Science

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“…Over the past 30 years, the Arctic freshwater cycle intensified as reflected by changes in snow cover (Bring et al, 2016), evapotranspiration from terrestrial vegetation (Bring et al, 2016), and precipitation (Vihma et al, 2016). It resulted in an increase of the freshwater discharge from North American and Eurasian rivers by ∼ 2.6 and ∼ 3.1 % per decade, respectively (Holmes et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Towards an assessment of riverine dissolved organic carbon in surface waters of the western Arctic Ocean based on remote sensing and biogeochemical modeling

Fouest

Matsuoka²,

Manizza

et al. 2018

Biogeosciences

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Abstract. Future climate warming of the Arctic could potentially enhance the load of terrigenous dissolved organic carbon (tDOC) of Arctic rivers due to increased carbon mobilization within watersheds. A greater flux of tDOC might impact the biogeochemical processes of the coastal Arctic Ocean (AO) and ultimately its capacity to absorb atmospheric CO 2 . In this study, we show that sea-surface tDOC concentrations simulated by a physical-biogeochemical coupled model in the Canadian Beaufort Sea for 2003-2011 compare favorably with estimates retrieved by satellite imagery. Our results suggest that, over spring-summer, tDOC of riverine origin contributes to 35 % of primary production and that an equivalent of ∼ 10 % of tDOC is exported westwards with the potential of fueling the biological production of the eastern Alaskan nearshore waters. The combination of model and satellite data provides promising results to extend this work to the entire AO so as to quantify, in conjunction with in situ data, the expected changes in tDOC fluxes and their potential impact on the AO biogeochemistry at basin scale.

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“…Shorelines were digitised manually in ArcGIS for all 12 images, at a scale of 1 : 600 for the four, older, coarser spatial resolution panchromatic images and a scale of 1 : 80 for the eight finer spatial resolution RGB orthomosaics. The shoreline was defined as the vegetation edge rather than the wet-dry line previously used in this region (Radosavljevic et al, 2016) because the vegetation edge was both more visually distinct and temporally consistent than the wet-dry line (Boak and Turner, 2005). Temporal consistency was essential to ensure meaningful assessment of coastal retreat over short time intervals (Río and Gracia, 2013).…”

Section: Image Alignment and Shoreline Mappingmentioning

confidence: 99%

“…M. Cunliffe et al: Drones observe eroding permafrost coastline mafrost . Coastal erosion mobilises large amounts of sediment, organic matter, and nutrients from permafrost Overduin et al, 2014;Retamal et al, 2008;Wegner et al, 2015), which are released into the nearshore waters and affect marine ecosystems (Bell et al, 2016;Dunton et al, 2006;Fritz et al, 2017). Several studies have reported signs of accelerating coastal erosion rates at locations around the Arctic, including the western Arctic (Barnhart et al, 2014;Jones et al, 2008Jones et al, , 2009bMars and Houseknecht, 2007;Radosavljevic et al, 2016) and Siberia Kritsuk et al, 2014;Novikova et al, 2018;Ogorodov et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Cunliffe¹

2019

Preprint

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Permafrost landscapes are changing around the Arctic in response to climate warming, with coastal erosion being one of the most prominent and hazardous features. Using drone platforms, satellite images, and historic aerial photographs, we observed the rapid retreat of a permafrost coastline on Qikiqtaruk -Herschel Island, Yukon Territory, in the Canadian Beaufort Sea. This coastline is adjacent to a gravel spit accommodating several culturally significant sites and is the logistical base for the Qikiqtaruk -Herschel Island Territorial Park operations. In this study we sought to (i) assess short-term coastal erosion dynamics over fine temporal resolution, (ii) evaluate short-term shoreline change in the context of long-term observations, and (iii) demonstrate the potential of low-cost lightweight unmanned aerial vehicles ("drones") to inform coastline studies and management decisions. We resurveyed a 500 m permafrost coastal reach at high temporal frequency (seven surveys over 40 d in 2017). Intra-seasonal shoreline changes were related to meteorological and oceanographic variables to understand controls on intra-seasonal erosion patterns. To put our short-term observations into historical context, we combined our analysis of shoreline positions in 2016 and 2017 with historical observations from 1952, 1970, 2000, and 2011. In just the summer of 2017, we observed coastal retreat of 14.5 m, more than 6 times faster than the long-term average rate of 2.2 ± 0.1 m a −1 . Coastline retreat rates exceeded 1.0 ± 0.1 m d −1 over a single 4 d period. Over 40 d, we estimated removal of ca. 0.96 m 3 m −1 d −1 . These findings highlight the episodic nature of shoreline change and the important role of storm events, which are poorly understood along permafrost coastlines. We found drone surveys combined with image-based modelling yield fine spatial resolution and accurately geolocated observations that are highly suitable to observe intra-seasonal erosion dynamics in rapidly changing Arctic landscapes.Published by Copernicus Publications on behalf of the European Geosciences Union.

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Influence of terrestrial organic matter in marine food webs of the Beaufort Sea shelf and slope

Cited by 71 publications

References 104 publications

Photodegraded dissolved organic matter from peak freshet river discharge as a substrate for bacterial production in a lake-rich great Arctic delta

Photodegraded dissolved organic matter from peak freshet river discharge as a substrate for bacterial production in a lake-rich great Arctic delta

Towards an assessment of riverine dissolved organic carbon in surface waters of the western Arctic Ocean based on remote sensing and biogeochemical modeling

Author responses to refaree feedback

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