Accelerated mass loss from the Greenland ice sheet leads to glacier retreat and an increasing input of glacial meltwater to the fjords and coastal waters around Greenland. These high latitude ecosystems are highly productive and sustain important fisheries, yet it remains uncertain how they will respond to future changes in the Arctic cryosphere. Here we show that marine-terminating glaciers play a crucial role in sustaining high productivity of the fjord ecosystems. Hydrographic and biogeochemical data from two fjord systems adjacent to the Greenland ice sheet, suggest that marine ecosystem productivity is very differently regulated in fjords influenced by either land-terminating or marine-terminating glaciers. Rising subsurface meltwater plumes originating from marine-terminating glaciers entrain large volumes of ambient deep water to the surface. The resulting upwelling of nutrient-rich deep water sustains a high phytoplankton productivity throughout summer in the fjord with marine-terminating glaciers. In contrast, the fjord with only land-terminating glaciers lack this upwelling mechanism, and is characterized by lower productivity.Data on commercial halibut landings support that coastal regions influenced by large marine-terminating glaciers have substantially higher marine productivity. These results suggest that a switch from marine-terminating to land-terminating glaciers can substantially alter the productivity in the coastal zone around Greenland with potentially large ecological and socio-economic implications.

Changes in large-scale climate conditions in the Northwest Atlantic caused a phase shift in productivity, altering trophic pathways that influence the growth, survival, and abundance of many species. Despite diverse population structures and management regimes, concurrent abundance declines in disparate North American and European Atlantic salmon populations suggest that conditions experienced at common marine areas may be causative. To understand the trophic mechanisms contributing to population declines, 1451 Atlantic salmon stomachs were collected and examined from individuals caught between 2006 and 2011 at the West Greenland feeding grounds. Standardized stomach content weights and stomach composition varied among years but not between stock complexes. Atlantic salmon consumed a variety of prey taxa, primarily capelin and Themisto sp., over a broad size spectrum. Standardized stomach content weight and proportions of taxa consumed were similar between historical (1965−1970) and contemporary samples, although lower-quality boreoatlantic armhook squid, nearly absent from historical data, was of moderate importance in contemporary samples, while higher-quality capelin decreased in importance. Furthermore, from 1968−2008 mean energy density estimates of capelin, the regional keystone forage species, decreased approximately 33.7%. This resulted in lower estimates of total energy consumption by Atlantic salmon over time. Results indicate that altered trophic dynamics caused by 40 yr of changing ocean conditions negatively influenced Atlantic salmon and likely many other commercially, culturally, and ecologically important species in the Northwest Atlantic. Determining the primary mechanisms that influence marine food-webs is necessary to fully understand and evaluate survival and productivity trends and to establish realistic management targets for commercial, recreational, and protected species.

Parallel evolution and the extent to which it involves gene reuse have attracted much interest. Whereas it has theoretically been predicted under which circumstances gene reuse is expected, empirical studies that directly compare systems showing high and low parallelism are rare. Three-spined stickleback (Gasterosteus aculeatus), where freshwater populations have been independently founded by ancestral marine populations, represent prime examples of phenotypic and genomic parallelism, but cases exist where parallelism is low. Based on RAD (restriction site associated DNA) sequencing, we analysed SNPs and chromosome inversions in populations in Denmark and Greenland showing low and high parallelism, respectively. We identified parallelism across freshwater populations in Greenland at genomic regions previously identified to be associated with marine-freshwater divergence. These same markers also separated Danish marine and freshwater sticklebacks, albeit to a weaker extent. Hence, parallelism was not absent in Denmark but possibly constrained by spatially and temporally varying selection. Divergence time estimates found one Danish freshwater population to be much older than the others. It also deviated strongly with respect to parallelism and may represent earlier postglacial colonization based on a different pool of standing variation and eliciting different adaptive responses to freshwater conditions. These findings provide empirical support to previous suggestions that the time since replicate populations had access to a common pool of standing variation is a major factor determining gene reuse. At last, based on the observed parallelism in the Greenlandic system we discuss the predictability of adaptive responses in newly established populations.

The term vulnerable marine ecosystem (VME) was introduced to facilitate the spatial management of deep-seas, identifying those habitats vulnerable to anthropogenic disturbance, such as trawling. Consistent interpretation of the VME definition has been hampered by an underlying paucity of knowledge about the nature and distribution of deep-sea habitats. Photographic and video platforms yield data rich, quantifiable imagery to address these knowledge gaps. A low-cost towed benthic video sled has been used to investigate deep-sea habitats and trawling impacts in west Greenland. A review of imagery from multiple cruises highlighted an area where benthic megafauna contributes to notable structural complexity on the continental slope of the Toqqusaq Bank. Quantitative analysis of imagery from this area provides the first description of a soft coral garden habitat and other communities. The coral garden and observed densities are considered in relation to the VME guidelines (FAO, 2009) and wider literature. The study proposes a 486 km 2 area spanning ∼60 km of continental slope as a VME. This has direct implications for the management of economically important deep-sea trawl fisheries, which are immediately adjacent. This furthers our knowledge and understanding of VMEs in North Atlantic, in a previously understudied region and demonstrates the utility of a low-cost video sled for identifying and describing VMEs.

Using social media, the Greenland Institute of Natural Resources collected data on the occurrence of pink salmon (Oncorhynchus gorbuscha) in 2019. Eighty-four pink salmon were reported from 22 locations across Greenland. This comprised 76 specimens from 2019 and 8 specimens from 2013 to 2018. Of these, 12 were caught in fresh water, and a single pink salmon was from the bottom of the Nuuk Fjord near the Kapisillit Riverthe only known river in Greenland where the Atlantic salmon (Salmo salar) spawn. It is unknown if pink salmon have reproduced in Greenland waters.