Greenland’s coastal margins are influenced by the confluence of Arctic and Atlantic waters, sea ice, icebergs, and meltwater from the ice sheet. Hundreds of spectacular glacial fjords cut through the ...coastline and support thriving marine ecosystems and, in some places, adjacent Greenlandic communities. Rising air and ocean temperatures, as well as glacier and sea-ice retreat, are impacting the conditions that support these systems. Projecting how these regions and their communities will evolve requires understanding both the large-scale climate variability and the regional-scale web of physical, biological, and social interactions. Here, we describe pan-Greenland physical, biological, and social settings and show how they are shaped by the ocean, the atmosphere, and the ice sheet. Next, we focus on two communities, Qaanaaq in Northwest Greenland, exposed to Arctic variability, and Ammassalik in Southeast Greenland, exposed to Atlantic variability. We show that while their climates today are similar to those of the warm 1930s–1940s, temperatures are projected to soon exceed those of the last 100 years at both locations. Existing biological records, including fisheries, provide some insight on ecosystem variability, but they are too short to discern robust patterns. To determine how these systems will evolve in the future requires an improved understanding of the linkages and external factors shaping the ecosystem and community response. This interdisciplinary study exemplifies a first step in a systems approach to investigating the evolution of Greenland’s coastal margins.
Northwards flowing Atlantic waters transport heat, nutrients, and organic carbon in the form of zooplankton into the eastern Greenland Sea and Fram Strait. Less is known of the contribution of ...phytoplankton advection in this current, the Atlantic Water Inflow (AWI) spanning from the North Atlantic to the Arctic Ocean. The in situ and advected primary production was estimated by using the physical-biological coupled SINMOD model, from northern Norway coast (along the Norwegian Atlantic Current, NAC), the West Spitsbergen Current (WSC) and the entrance to the Arctic Ocean in northern Fram Strait. The simulation results show that changes in phytoplankton biomass at any one location along the AWI are supported primarily by advection. This advection is 5-50 times higher than the biomass photosynthesized in situ, seasonally variable, with minimum contribution in June, at the time of maximum in situ primary production. Advection in the NAC transports phytoplankton biomass from areas of higher production in the south, contributing to the maintenance of phytoplankton productivity further north. In situ productivity further decreases north of Svalbard Archipelago, at the entrance to the Arctic Ocean. Excess in situ annual production in northern WSC is exported to the Arctic Ocean during the growth season (April to September). The balance between in situ and advected primary production defines three main regions along the AWI, presumably modulated by the spatial and temporal variability of copepod grazing. As the sea ice reduces its annual extent and warmer waters enter the Arctic Ocean, ecological characteristics of the ice-free WSC with its AWI signature could extend north and east of Svalbard and into the central Arctic. Advection thus constitutes an important link connecting marine ecosystems of the Arctic and Atlantic Ocean, mainly at the gateways.
Phytoplankton primary production in the Arctic Ocean has been increasing over the last two decades. In 2019, a record spring bloom occurred in Fram Strait, characterized by a peak in chlorophyll that ...was reached weeks earlier than in other years and was larger than any previously recorded May bloom. Here, we consider the conditions that led to this event and examine drivers of spring phytoplankton blooms in Fram Strait using in situ, remote sensing, and data assimilation methods. From samples collected during the May 2019 bloom, we observe a direct relationship between sea ice meltwater in the upper water column and chlorophyll a pigment concentrations. We place the 2019 spring dynamics in context of the past 20 years, a period marked by rapid change in climatic conditions. Our findings suggest that increased advection of sea ice into the region and warmer surface temperatures led to a rise in meltwater input and stronger near‐surface stratification. Over this time period, we identify large‐scale spatial correlations in Fram Strait between increased chlorophyll a concentrations and increased freshwater flux from sea ice melt.
Phytoplankton primary production in the Arctic Ocean has been increasing over the last two decades. We study potential drivers behind this trend—with a focus on a record bloom in Fram Strait in May 2019—using in situ, remote sensing, and data assimilation methods. Our analysis suggests that advection of sea ice into the region and warmer surface temperatures have led to a rise in meltwater input and stronger near‐surface stratification in Fram Strait over the past two decades. We argue that the near‐surface stratification confines phytoplankton to the light‐bathed surface waters which may boost phytoplankton growth in the spring.
Cobalt (Co) is an important bioactive trace metal that is the metal
cofactor in cobalamin (vitamin B12) which can limit or co-limit
phytoplankton growth in many regions of the ocean. Total dissolved ...and
labile Co measurements in the Canadian sector of the Arctic Ocean during the
U.S. GEOTRACES Arctic expedition (GN01) and the Canadian International Polar
Year GEOTRACES expedition (GIPY14) revealed a dynamic biogeochemical cycle
for Co in this basin. The major sources of Co in the Arctic were from shelf
regions and rivers, with only minimal contributions from other freshwater
sources (sea ice, snow) and eolian deposition. The most striking feature
was the extremely high concentrations of dissolved Co in the upper 100 m,
with concentrations routinely exceeding 800 pmol L−1 over the shelf
regions. This plume of high Co persisted throughout the Arctic basin and
extended to the North Pole, where sources of Co shifted from primarily
shelf-derived to riverine, as freshwater from Arctic rivers was entrained in
the Transpolar Drift. Dissolved Co was also strongly organically complexed
in the Arctic, ranging from 70 % to 100 % complexed in the surface and deep
ocean, respectively. Deep-water concentrations of dissolved Co were
remarkably consistent throughout the basin (∼55 pmol L−1), with concentrations reflecting those of deep Atlantic water and
deep-ocean scavenging of dissolved Co. A biogeochemical model of Co cycling
was used to support the hypothesis that the majority of the high surface Co
in the Arctic was emanating from the shelf. The model showed that the high
concentrations of Co observed were due to the large shelf area of the
Arctic, as well as to dampened scavenging of Co by manganese-oxidizing (Mn-oxidizing)
bacteria due to the lower temperatures. The majority of this scavenging
appears to have occurred in the upper 200 m, with minimal additional
scavenging below this depth. Evidence suggests that both dissolved Co (dCo) and labile Co (LCo) are increasing over time on the Arctic shelf, and these limited temporal results are consistent
with other tracers in the Arctic. These
elevated surface concentrations of Co likely lead to a net flux of Co out of
the Arctic, with implications for downstream biological uptake of Co in the
North Atlantic and elevated Co in North Atlantic Deep Water. Understanding
the current distributions of Co in the Arctic will be important for
constraining changes to Co inputs resulting from regional intensification of
freshwater fluxes from ice and permafrost melt in response to ongoing
climate change.
Rapid mass loss from the Greenland Ice Sheet is affecting sea level and, through increased freshwater discharge, ocean circulation, sea-ice, biogeochemistry, and marine ecosystems around Greenland. ...Key to interpreting ongoing and projecting future ice loss, and its impact on the ocean, is understanding exchanges of heat, freshwater, and nutrients that occur at Greenland’s marine margins. Processes governing these exchanges are poorly understood because of limited observations from the regions where glaciers terminate into the ocean and the challenge to model the spatial and temporal scales involved. Thus, notwithstanding their importance, ice sheet/ocean exchanges are poorly represented or not accounted for in models used for projection studies. Widespread community consensus maintains that concurrent and long-term records of glaciological, oceanic, and atmospheric parameters at the ice sheet/ocean margins are key to addressing this knowledge gap by informing understanding, and constraining and validating models. Through a series of workshops and documents endorsed by the community-at-large, a framework for an international, collaborative, Greenland Ice sheet-Ocean Observing System (GrIOOS), that addresses societal needs for the impact of a changing Greenland Ice Sheet, has been proposed. This system would consist of a set of ocean, glacier, and atmosphere essential variables to be collected at a number of diverse sites around Greenland for a minimum of two decades. Internationally agreed upon data protocols and data sharing policies would guarantee uniformity and availability of the information for the broader community. Its development, maintenance, and funding will require close international collaboration. Engagement of end-users, local people, and groups already active in these areas, as well as synergy with ongoing, related, or complementary networks will be key to its success and effectiveness.
Eastern Fram Strait and the shelf slope region north of Svalbard is dominated by the advection of warm, salty and nutrient-rich Atlantic Water (AW). This oceanic heat contributes to keeping the area ...relatively free of ice. The last years have seen a dramatic decrease in regional sea ice extent, which is expected to drive large increases in pelagic primary production and thereby changes in marine ecology and nutrient cycling. In a concerted effort, we conducted five cruises to the area in winter, spring, summer and fall of 2014, in order to understand the physical and biogeochemical controls of carbon cycling, for the first time from a year-round point of view. We document (1) the offshore location of the wintertime front between salty AW and fresher Surface Water in the ocean surface, (2) thermal convection of Atlantic Water over the shelf slope, likely enhancing vertical ñnutrient fluxes, and (3) the importance of ice melt derived upper ocean stratification for the spring bloom timing. Our findings strongly confirm the hypothesis that this ``Atlantification'', as it has been called, of the shelf slope area north of Svalbard resulting from the advection of AW alleviates both nutrient and light limitations at the same time, leading to increased pelagic primary productivity in this region.
Warming along the Antarctic Peninsula has led to an increase in the export of glacial meltwater to the coastal ocean. While observations to date suggest that this freshwater export acts as an ...important forcing on the marine ecosystem, the processes linking ice-ocean interactions to lower trophic-level growth, particularly in coastal bays and fjords, are poorly understood. Here, we identify salient hydrographic features in Barilari Bay, a west Antarctic Peninsula fjord influenced by warm modified Upper Circumpolar Deep Water. In this fjord, interactions between the glaciers and ocean act as a control on coastal circulation, contributing to the redistribution of water masses in an upwelling plume and a vertical flux of nutrients towards the euphotic zone. This nutrient-rich plume, containing glacial meltwater but primarily composed of ambient ocean waters including modified Upper Circumpolar Deep Water, spreads through the fjord as a 150-m thick layer in the upper water column. The combination of meltwater-driven stratification, long residence time of the surface plume owing to weak circulation, and nutrient enrichment promotes phytoplankton growth within the fjord, as evidenced by shallow phytoplankton blooms and concomitant nutrient drawdown at the fjord mouth in late February. Gradients in meltwater distributions are further paralleled by gradients in phytoplankton and benthic community composition. While glacial meltwater export and upwelling of ambient waters in this way contribute to elevated primary and secondary productivity, subsurface nutrient enhancement of glacially-modified ocean waters suggests that a portion of these macronutrients, as well any iron upwelled or input in meltwater, are exported to the continental shelf. Sustained atmospheric warming in the coming decades, contributing to greater runoff, would invigorate the marine circulation with consequences for glacier dynamics and biogeochemical cycling within the fjord. We conclude that ice-ocean interactions along the Antarctic Peninsula margins act as an important control on coastal marine ecosystems, with repercussions for carbon cycling along the west Antarctic Peninsula shelf as a whole.
Anthropogenic CO2 emissions associated with fossil fuel combustion have caused declines in baseline oceanic δ13C values. This phenomenon, called the Suess effect, can confound comparisons of marine ...δ13C data from different years. The Suess effect can be corrected for mathematically; however, a variety of disparate techniques are currently used, often resulting in corrections that differ substantially. SuessR is a free, user‐friendly tool that allows researchers to calculate and apply regional Suess corrections to δ13C data from marine systems using a unified approach.
SuessR updates existing methods for calculating region‐specific Suess corrections for samples collected from 1850 to 2020. It also estimates changes in phytoplankton 13C fractionation associated with increasing water temperature and aqueous CO2 concentrations, referred to here as the Laws effect. SuessR version 0.1.3 contains four built‐in regions, including three in the subpolar North Pacific (Bering Sea, Aleutian Islands and Gulf of Alaska) and one North Atlantic region (Subpolar North Atlantic). Users can also supply environmental data for regions not currently built into SuessR to generate their own custom corrections.
In 2020, net corrections (Suess + Laws corrections) were as follows—Bering Sea: 1.29‰; Aleutian Islands: 1.30‰, Gulf of Alaska: 1.30‰; and Subpolar North Atlantic: 1.31‰ (compared to a global atmospheric CO2 change of ~2.43‰ across the same period). For samples collected in 2020, the net correction exceeds instrumental error (±0.2‰) when making comparisons across only eight years (i.e. 2013–2020). The magnitude of the Suess effect calculated by SuessR aligns with published estimates, whereas the Laws effect is smaller than previously calculated, resulting from updated estimates of average community cell sizes, growth rates and permeability of phytoplankton plasmalemmas (the plasma membrane which bounds the cell) to CO2.
The increasing magnitude of the Suess effect means this phenomenon is no longer only of concern to historical ecologists, but now affects contemporary ecological studies using δ13C data. This highlights the importance of a unified approach for generating Suess corrections. The SuessR package provides a customizable tool that is simple to use and will improve the interpretability and comparability of future stable isotopic studies of marine ecology.
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