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The accelerated melt of the Greenland Ice Sheet has been linked to a sudden increase in the presence of warm subsurface coastal water in west Greenland. Yet pathways of warm coastal water along the entire west Greenland coast have remained largely unstudied. Here we present the first, near‐synoptic hydrographic observations at both the continental slope and fjord entrances of the west Greenland coastal system from Cape Farewell (59°N) to Melville Bay (75°N) in summer 2016. We observed a distinct north‐south division in the water mass distribution in west Greenland, approximately partitioned by the northern part of Davis Strait, and a division between the continental slope and fjord entrances. Waters from the regional southern freshwater source with origin in the East Greenland Current that rounds Cape Farewell are not observed to enter Baffin Bay. The regional heat source transported by the west Greenland Current is blocked by Southwest Greenland Coastal Water in the south but the deep connections in the north allow warm deep Subpolar Mode Water to enter fjords. Furthermore, we observed cold and relative saline Baffin Bay Polar Water over the inner part of the banks, periodically reaching as far south as 64°N, suggesting the presence of an undescribed southward current at the Southwest Greenland continental shelf. Key Points: The regional southern freshwater source transported northward along the Greenland west coast did not enter Baffin Bay during summer 2016North of Davis Strait, warm deep Subpolar Mode Water may enter the deep silled fjords unobstructedBaffin Bay Polar Water is observed on the Southwest Greenland coast as far south as 64°N suggesting a seasonal southward coastal current [ABSTRACT FROM AUTHOR]

High-latitude fjord environments are undergoing dynamic seasonal changes, affecting spatio-temporal patterns in planktonic abundances. To investigate how physical gradients impact sub-Arctic planktonic protists (> 20 μm), a seasonal transect study was performed in 2013 during three periods of planktonic succession: spring, summer, and autumn. The samples were collected from the glacier-fjord-ocean transect in SW Greenland using two complementary sampling methods, i.e. net hauls (20-μm net) and Niskin bottles. The key drivers of the distribution of planktonic groups and dominant taxa were hydrographic properties (defined as ‘time’, salinity, and temperature) reflecting the area’s seasonally changing circulation system. Cold and relatively saline waters in spring favoured the single haptophyte species Phaeocystis cf. pouchetii, while in summer, fresher waters influenced by glacial discharge favoured diatoms, followed by dinoflagellates and predatory ciliates in autumn. Our findings reveal a monodominant structure among the planktonic protists observed in each key sub-region and in each season. (1) Gedaniella boltonii (spring) was associated with inner fjord upwelling, (2) Chaetoceros sp. (summer) and Chaetoceros cf. socialis (autumn) were linked to ‘glacial meltwater’ circulation in the main fjord, and (3) Thalassiosira poroseriata (summer) and Skeletonema sp. (autumn) characterized warm and relatively saline offshore waters influenced by the West Greenland Current. The observed spatio-temporal patterns were linked to changes in hydrographic regimes driven by the interplay between the melting of the Greenland Ice Sheet and inflows of offshore, Atlantic-sourced waters. [ABSTRACT FROM AUTHOR]

The Greenland Ice Sheet releases large amounts of freshwater, which strongly influences the physical and chemical properties of the adjacent fjord systems and continental shelves. Glacial meltwater input is predicted to strongly increase in the future, but the impact of meltwater on the carbonate dynamics of these productive coastal systems remains largely unquantified. Here we present seasonal observations of the carbonate system over the year 2013 in the surface waters of a west Greenland fjord (Godthåbsfjord) influenced by tidewater outlet glaciers. Our data reveal that the surface layer of the entire fjord and adjacent continental shelf are undersaturated in CO2 throughout the year. The average annual CO2 uptake within the fjord is estimated to be 65 g Cm-2 yr-1, indicating that the fjord system is a strong sink for CO2. The largest CO2 uptake occurs in the inner fjord near to the Greenland Ice Sheet and high glacial meltwater input during the summer months correlates strongly with low pCO2 values. This strong CO2 uptake can be explained by the thermodynamic effect on the surface water pCO2 resulting from the mixing of fresh glacial meltwater and ambient saline fjord water, which results in a CO2 uptake of 1.8 mgC kg-1 of glacial ice melted. We estimated that 28% of the CO2 uptake can be attributed to the input of glacial meltwater, while the remaining part is due to high primary production. Our findings imply that glacial meltwater is an important driver for undersaturation in CO2 in fjord and coastal waters adjacent to large ice sheets. [ABSTRACT FROM AUTHOR]