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Reliable high‐resolution, pre‐observational‐period sea‐ice datasets are rare but critical for contextualizing recent sea‐ice declines and future scenarios. We combine sedimentary ancient DNA of the sea‐ice dinoflagellate Polarella glacialis (Pgla‐sedaDNA) with selected highly branched isoprenoid (HBI) biomarkers alongside other indicators to reconstruct sub‐decadal sea‐ice changes in a marine archive from the Antarctic Peninsula that extends to ~ 1900 CE. Pre‐1940 CE, the continuously present sea‐ice biomarker IPSO25 yet absent Pgla‐sedaDNA, along with low open‐water biomarkers and total organic carbon (TOC), imply more prominent seasonal sea ice and lower productivity under cooler climate. Post‐1940 CE, rising Pgla‐sedaDNA and open‐water HBIs under climate warming reflect young ice with a retreating sea‐ice edge. Over the last two decades, lower Pgla‐sedaDNA, higher open‐water HBIs and TOC infer known warming, sea‐ice reduction, and increased productivity. Our multiproxy‐based palaeo‐histories agree well with observational data, highlighting the potential of this combination of proxies for nuanced and long‐term sea‐ice reconstructions. [ABSTRACT FROM AUTHOR]

Electronic tags are often used to track the freshwater‐marine migrations of smolts, where smolts are captured for tagging pre‐migration (e.g., via electrofishing) or during‐migration (e.g., via traps). Pre‐migration capture allows smolts to initiate and complete their downstream migration unhindered, but risks smolt loss before the migration commences. The contrary is the case for during‐migration trap‐caught smolts, but trapping smolts temporarily halts their seaward journey which may negatively impact their progress. This study investigated the effect of trapping on the behaviour and survival of migrating Atlantic salmon (Salmo Salar) smolts using acoustic telemetry. We compared the movements and survival of smolts tagged before the smolt run captured by electrofishing ("comparator") with smolts trapped and tagged during the smolt run ("trapped"). A total of 478 smolts were tagged and released in River Skjern (2020 and 2022), Denmark, and 82 smolts in River Ballycastle (2022), Northern Ireland, and their seaward movements were monitored using acoustic receivers deployed in the river, fjord, and coastal area. In River Skjern in 2022, comparator smolts migrated earlier than trapped smolts, likely because these constituted more of the larger‐sized, earlier migrating individuals. We found no differences in descent trajectories, diel patterns, progression rates, or survival between trapped smolts and comparator smolts in any of the rivers or study years. Thus, our results support the use of during‐migration trapping as a low‐impact method to capture smolts for telemetry studies, with trapped samples (if held <24 h) yielding comparable results in terms of behaviour and survival with non‐delayed pre‐migration tagged fish. [ABSTRACT FROM AUTHOR]

Juvenile Atlantic salmon (Salmo salar), known as post-smolt as they enter the sea, undergo an arduous migration from their natal rivers to their feeding grounds in the North Atlantic Ocean. It has become increasingly important to understand how post-smolts use the fjord environment as they migrate in order to properly assess the potential threats posed by large-scale salmon farming. Chief among these threats is the increased numbers of ectoparasitic salmon lice (Lepeophtheirus salmonis) inhabiting the water column, which are known to have specific depth preferences based on light, temperature, and salinity. Here, we present data on the depth use of wild Atlantic salmon post-smolts migrating through fjords. We aimed to investigate to what extent depth use varied throughout the fjord and from year to year. Using acoustic telemetry, tagged fish from four rivers in two fjords in western Norway were monitored as they migrated towards the open sea during two consecutive years. We found that post-smolts predominantly migrated in the top three meters of the water column throughout the length of both fjord systems. Among 61 successful migrants and 7013 detections, 98% of detections were in the top three meters of the water column. This corresponds well with past findings showing similar depth use in hatchery-reared smolt and in adult Atlantic salmon kelts returning to their feeding grounds after spawning. We found little evidence of a consistent diel pattern in depth use. Our results support assumptions of representative sampling when trawling the upper portion of the water column for post-smolts in order to estimate sea lice infection rates and may improve the precision of efforts to model salmon lice infection risk. The results may also be valuable in evaluating other threats to wild salmon. [ABSTRACT FROM AUTHOR]

Arctic fjords are inherently vulnerable to global warming, particularly because of the substantial freshwater influx resulting from the melting of glaciers. In this study, precipitation, river water, surface ice, and seawater samples from Kongsfjorden were collected to identify the main sources of freshwater. The dual water isotope (δ18O and δD) results and temperature–salinity profiles revealed that between 0% and 7% freshwater contributed to the fjord's water. Furthermore, different freshwater sources for surface and deep water were identified by the dual water isotope analysis. Turbidity profiles confirmed the alter in particle discharge associated with surface runoff and subglacial discharge. Our study highlighted the sensitivity of water isotope analysis in elucidating the hydrological processes within the fjord system and demonstrated its potential for investigating the impact of meltwater on biological processes in the Arctic. [ABSTRACT FROM AUTHOR]

Little is known about the role of remote and sparsely populated Arctic coastal zones in the microplastic cycle. Distribution of microplastics was studied in the Svalbard fjords in June – July 2022 with the main goal of assessing rivers' role in the fate of microplastic in Arctic coastal waters. Surface microplastics (0 – 20 cm depth, 500 – 5000 µm size) were sampled with a neuston net in triplicate per study site in parallel with sampling of subsurface microplastics with a pump system (1.5 m depth, 100 – 5000 µm size). The central part of Isfjorden and its several branches covering populated and unpopulated fjords were studied; the sampling was conducted during an intense riverine discharge in all studied sites. Maximum abundance of surface microplastics (71,400 items/km2 or 0.19 iterms/m3, 0.19 mg/m3) was found along the river plume border in the middle of populated Adventfjorden indicating importance of both local sources and surface hydrodynamics in the formation of microplastics accumulation hotspots. All other unpopulated fjords were free of the floating on the sea surface microplastics as river discharge prevented transport of microplastics inside the fjords. The highest concentration of subsurface microplastics was found in the central part of Isfjorden and the lowest – in river plume waters, which also indicates the removal of microplastics from the inner part of fjords during an intensive river discharge. Our results may suggest that Arctic rivers flowing through unpopulated areas bring clean water and thereby reduce level of microplastic pollution in the coastal waters. In contrast to the rest of the world's ocean, rivers are not the main source of microplastic pollution in the Arctic Ocean. [ABSTRACT FROM AUTHOR]

Halifax Harbour, a crucial Atlantic Canadian port, has extensive commercial, environmental, and strategic value to Canadians. Despite thorough hydrographic research, knowledge about the influence of the bottom current on the resuspension of sediments within the Harbour is lacking. To address this knowledge gap, we utilized a high-resolution, three-dimensional, barotropic finite volume community ocean model (FVCOM) to simulate the tidal-driven maximum bottom current in the Harbour. We used the critical Shields parameter, a threshold for sediment movement, to quantify the areas susceptible to sediment resuspension. Our results indicate that regions in the Narrows and west of McNabs Island are susceptible to sediment resuspension due to the interaction of maximum bottom current and sediment grain sizes. These findings are important for detecting sediment changes in the Harbour and potentially improving existing monitoring and management practices. [ABSTRACT FROM AUTHOR]

Greenland's fjord ecosystems are strongly influenced by meltwater discharge from glaciers. Marine-terminating glaciers can significantly enhance primary production during the melt season (compared to land-terminating glaciers), but their impact on secondary producers is not well understood. Here, we study seasonal changes in the zooplankton community (>50 μm) and grazing rates along two fjord transects in southwest Greenland influenced by different glacier types. Zooplankton biomass was comparable between the fjords, but community composition differed during summer. Nuup Kangerlua, a predominantly marine-terminating system, was characterized by large, herbivorous copepods and a longer summer grazing period in connection with the summer bloom. Ameralik, influenced by a land-terminating glacier, was characterized by small, omnivorous copepods, particularly Microsetella norvegica and Oncaea spp. and indicated a faster post-bloom transition towards regenerated production. Local hydrographic conditions also impact copepod biomass. A station with high biomass was found in Ameralik, potentially linked to a frontal zone where fjord water masses meet, providing favorable grazing conditions. We hypothesize that a future transformation from marine- to land-terminating glaciers could result in an increased abundance of smaller copepods, as observed in Ameralik. Such a community would constitute a less lipid-rich food source for higher trophic levels. [ABSTRACT FROM AUTHOR]

Arctic fjords, being transitional areas between glacier‐covered land and the ocean, are characterized by strong environmental gradients. The seasonal melting of glaciers generates strong turbidity and primary production antagonist gradients, which can affect benthic habitats. Two sampling campaigns were carried out in Kongsfjorden (Svalbard, Arctic Ocean) in May and August 2021 to investigate seasonal changes in benthic foraminifera spatial distribution and ecosystem functioning along a longitudinal transect of 10 km from the Kronebreen tidewater glacier front. Concurrently, organic matter quantity and biochemical composition, sediment grain size, and physical parameters of the water masses were investigated as possible driving factors of benthic ecosystem responses. In a previous study, three statistically determined foraminiferal biozonations (glacier proximal, medial, and distal) were observed on the basis of their species content within the closest 10 km from the glacier front, presenting similar assemblages in both seasons. Our results indicate that foraminiferal distribution at the local scale is mainly driven by physical and geochemical gradients induced by melting waters and sediment discharges from the tidewater glacier occurring during summer. Due to the climate change, the melting season is expected to last longer and increasing global temperature will much probably accelerate the melting processes. Our findings strongly support the use of foraminifera as bioindicators to monitor the effects of ongoing climate change on the benthic ecosystems of Arctic fjords and, accessorily, as proxies for reconstructing glacier front positions in the recent past. [ABSTRACT FROM AUTHOR]

Glaciomarine fjords dominate the coastal margin of the West Antarctic Peninsula. Studies in similar habitats in the Arctic have shown that benthic biodiversity and ecosystem functioning in inner and middle fjord basins are reduced by turbidity and sedimentation disturbance caused by climate warming–enhanced glacial melting. In contrast, the inner and middle fjord basins along the West Antarctic Peninsula are characterized as productivity and biodiversity hotspots, but benthic ecosystem functions remain unevaluated. In 2015–2016, we conducted sediment respiration and 13C pulse‐chase experiments to assess benthic ecosystem functions along a five‐station transect at ~ 500–600 m depths from the inner Andvord Bay fjord, through to Gerlache Strait, and onto the open continental shelf. Incubation samples from the inner and middle basins of Andvord Bay showed peaks in background seafloor respiration, benthic biomass, and uptake of labeled algal biomass compared to more outlying stations; the continental shelf exhibited the lowest levels of these variables, as well as dissolved inorganic carbon production. Macrofaunal community uptake was responsible for most of the C processing in the inner and middle parts of the fjord (> 45%) while dissolved inorganic carbon was the dominant repository of processed C near the fjord mouth and on the continental shelf (> 80%). The inner parts of Andvord Bay are hotspots of benthic C‐cycling and metabolism, in addition to biodiversity. Ongoing climate warming is likely to negatively impact these inner‐fjord hotspots by increasing meltwater input and sedimentation disturbance, yielding a reduction in the input and recycling of labile detritus at the seafloor in the inner‐middle fjord. [ABSTRACT FROM AUTHOR]

Marine sediments bury ∼160 Tg of organic carbon (OC) annually and represent an essential component of the global carbon cycle. OC burial is inherently multifactorial; however, in the past decade, the role of iron in regulating OC burial via the formation of organo‐mineral associations, known as "rusty carbon sink," has been extensively studied. Despite widespread recognition, the origin of the OC preserved within these associations and the effect of the bottom‐water oxygenation on their stability are still debated. Here, we investigate the rusty carbon sink in sediments collected across transects from the head to mouth of three Swedish fjords presenting contrasting bottom‐water oxygenation regimes (the oxic Hake fjord, seasonally hypoxic Gullmar fjord, and anoxic By fjord). We found that the oxygenation regimes, the intensity of benthic iron cycling or the OC origin have little to no influence on the amount of OC bound to Fe (OC – Fe). The lack of correlation with any of the parameters studied, in combination with an increase in the OC – Fe in the fjords with riverine input suggest, at least partially, an allochthonous origin of these organo‐mineral associations. Our results also show that the rusty carbon sink plays a modest role in the OC burial in these fjords (∼6% OC is bound to Fe). While these fjords still represent important OC burial hotspots with an average of ∼35 g C m−2 buried annually, the OC burial is controlled by other sedimentary processes, such as the high mass accumulation rates found in these fjord systems. Plain Language Summary: Marine sediments are critical reservoirs of organic carbon playing a significant role regulating the Earth's climate. Numerous studies have examined how iron influences carbon storage through the formation of organo‐mineral associations, often referred to as the "rusty carbon sink." Ongoing debates still persist regarding the organic carbon source and the impact of the oxygen levels in bottom waters on the stability of these organo‐mineral associations. We investigate sediment samples from three distinct Swedish fjords, each characterized by different bottom waters oxygen concentrations. Surprisingly, our findings indicate that neither oxygen levels nor iron content significantly affected the carbon storage associated with iron. Additionally, the origin of the carbon did not play a major role in this process. Although only a small fraction of the total carbon content in these sediments is preserved by iron, the fjords remain crucial for carbon storage. Our results suggest that other factors, beyond oxygen and iron levels, may play a more significant role in the preservation and stability of organic carbon in these environments. Key Points: Low organic carbon‐iron (OC – Fe) associations in fjord sedimentsNo clear relation with the sedimentary dynamics, pre‐formed OC – Fe associations likely transported by rivers (at least partially)Fjords represent organic carbon hotspot, despite low rusty carbon sink [ABSTRACT FROM AUTHOR]

Ambient noise measurements from an Arctic fjord during summer and winter are analyzed using spectral, coherence, and directionality estimates from a vertically separated pair of hydrophones. The primary noise sources attributed to wind, shipping, and ice activity are categorized and coherence is arrived at. Estimates of the noise field directionality in the vertical and its variation over time and between seasons are used to strengthen the analysis of the time-varying nature of noise sources. Source identification using such processing techniques serves as a valuable tool in passive acoustic monitoring systems for studying ice dynamics in glacierized fjords. [ABSTRACT FROM AUTHOR]

Studying ocean tides with satellite altimetry has traditionally been difficult in coastal regions. The 1 day repeat of the Cal/Val phase of SWOT provides a unique dataset that can be exploited for tidal analysis. In this work, KaRIn data from the SWOT Cal/Val phase are analyzed in two coastal regions to present a first look at the possibilities for tidal analysis from SWOT. The areas are: (a) Bristol Channel and (b) Great South Bay. When benchmarked against in situ measurements in these regions, substantial improvements over tide models, which typically report errors exceeding tens of centimeters and degrees, are seen. Specifically, the SWOT ocean‐tide estimates exhibit amplitude discrepancies ranging from 1.75 to 3 cm and phase lag discrepancies between 1.75° and 2.75° when compared with in situ tide gauge data. These findings underscore the value of SWOT for tidal research in complex coastal regions. Plain Language Summary: Estimating ocean tides in the coastal region has challenged tide modelers for decades. The recently launched SWOT satellite provides the opportunity to derive estimations of ocean tides at unprecedented spatial scales thanks to the innovative wide‐swath measurement principle, particularly in complex coastal regions. The mission's Calibration and Validation (Cal/Val) phase is particularly interesting for tidal research, as the tide‐favorable orbit allows for the derivation of the major tidal constituents with a relatively short time series of SWOT data. This manuscript evaluates the largest tidal constituent, the principal lunar M2 ${\mathrm{M}}_{2}$ tide, derived from SWOT's Cal/Val phase within two complex coastal regions. Results within the Bristol Channel and the Great South Bay demonstrate unprecedented spatial variability in the amplitude and phase lag of the M2 ${\mathrm{M}}_{2}$ tide. Additionally, with respect to in situ measurements, SWOT‐derived estimates resulted in reduced errors compared with global tide models in these complex coastal regions. The initial insights demonstrated several strengths and opportunities for using SWOT to improve tide models and new avenues of research with satellite measurements of ocean tides, particularly within fjords and estuaries. Key Points: SWOT KaRIn data from the Cal/Val phase is used to derive M2 ${\mathrm{M}}_{2}$ tide in two complex coastal regionsResults demonstrate the spatial variability of amplitude and phase lag of coastal tidesSWOT KaRIn measurements are useful for studying tidal flats and ocean tides in river mouths and estuaries [ABSTRACT FROM AUTHOR]

Several climate-driven processes take place in the Arctic fjords. These include ice–ocean interactions, biodiversity and ocean circulation pattern changes, and coastal erosion phenomena. Conducting long-term oceanographic monitoring in the Arctic fjords is, therefore, essential for better understanding and predicting global environmental shifts. Here we address this issue by introducing a new hydrographic dataset from Hornsund, a fjord located in the southwestern part of the Svalbard archipelago. Hydrographic properties have been monitored with vertical temperature, salinity and depth profiles in several locations across the Hornsund fjord from 2015 to 2023. From 2016 onward, dissolved oxygen and turbidity data are available for the majority of casts. The dataset contributes to the so far infrequent observations, especially in spring and autumn, and extends the observations, typically concentrated in the central fjord, to the areas adjacent to the tidewater glaciers. Because sediment discharge from glaciers and land is an inseparable part of the glacier–ocean interactions, the suspended sediment concentration in the water column and the daily sedimentation rate adjacent to the tidewater glaciers are monitored with regular water sampling and bottom-moored sediment traps. Here we present the planning and execution of the monitoring campaign from the collection of the data to the postprocessing methods. All datasets are publicly available in the repositories referred to in the "Data availability" section of this paper. [ABSTRACT FROM AUTHOR]

Southeast Greenland (SEG) is characterized by complex morphology and environmental processes that create dynamic habitats for top marine predators. Active glaciers producing solid-ice discharge, freshwater flux, offshore sea ice transport, and seasonal landfast-ice formation all contribute to a variable, transient environment within SEG fjord systems. Here, we investigate a selection of physical processes in SEG to provide a regional characterization that reveals physical system processes and supports biological research. SEG fjords exhibit high fjord-to-fjord variability regarding bathymetry, size, shape, and glacial setting, influencing some processes more than others. For example, during fall, the timing of offshore sea ice formation near SEG fjords progresses temporally when moving southward across latitudes, while the timing of offshore sea ice disappearance is less dependent on latitude. The rates of annual freshwater flux into fjords, however, are highly variable across SEG, with annual average input values ranging from ∼ 1 × 108 to ∼ 1.25 × 1010 m3 (∼ 0.1–12.5 Gt) for individual fjords. Similarly, the rates of solid-ice discharge in SEG fjords vary widely – partly due to the irregular distribution of active glaciers across the study area (60–70° N). Landfast sea ice, assessed for eight focus fjords, is seasonal and has a spatial distribution highly dependent on individual fjord topography. Conversely, glacial ice is deposited into fjord systems year-round, with the spatial distribution of glacier-derived ice depending on the location of glacier termini. As climate change continues to affect SEG, the evolution of these metrics will vary individually in their response, and next steps should include moving from characterization to system projection. Due to the projected regional ice sheet persistence that will continue to feed glacial ice into fjords, it is possible that SEG could remain a long-term refugium for polar bears and other ice-dependent species on a centennial to millennial scale, demonstrating a need for continued research into the SEG physical environment. [ABSTRACT FROM AUTHOR]

Rock avalanches in fjord environments can cause direct catastrophic damage and trigger secondary submarine landslides and tsunamis. These are well-documented in Greenland, Norway, and Alaska but have gone largely unreported in the extensive fjord terrain of the eastern Canadian Arctic. We provide the first inventory of rock avalanche deposits in northeastern Baffin Island—a region characterized by moderate to high seismic hazard, steep and high-walled fjords and glacial valleys, active deglaciation, and observed climate warming. Over a broad study area of ~60,000 km2, one sixth of the terrain had sufficient slope height and gradient to potentially generate rock avalanches. Within that hazard zone, we identified eight rock avalanche deposits at six locations. Only three rock avalanche deposits at two locations are dated, using aerial imagery (1958-present), to the last century while five deposits at four locations are inferred as syn- to post-glacial, likely occurring shortly after local debuttressing. These total numbers fall well below documented inventories from Greenland, Norway, and Alaska. We hypothesize that (1) continuous permafrost persists throughout this region and continues to act as a stabilizing factor and (2) rock mass quality is high in areas of most extreme relief contrast within the study region relative to analogous high-latitude fjord systems such as those in southwestern Greenland. We suggest that Baffin Island is currently in a period of quasi-stability that follows the intense instability during initial deglaciation, yet precedes the higher anticipated slope instability that may occur during permafrost degradation. [ABSTRACT FROM AUTHOR]

Interindividual variability in habitat preferences affect local abundance and residency times. Within a population range, this can lead to sectors having a continuous flow of unique individuals, with others being used by the same set of resident individuals. These patterns of habitat use by individuals, referred to here as individual spatial mixing, can have important implications for ecological and evolutionary processes. This study proposes a novel approach for estimating the degree of individual spatial mixing in an endangered beluga population, based on the comparison of local individual diversity obtained from photo‐identification data against abundance indices derived from systematic aerial surveys. Divergences between long‐term indices of abundance and diversity were observed across many sectors within the population's summer habitat. This was the case notably for the Saguenay Fjord, where on average only 1.8% of the total population count was detected during summer aerial surveys, but where 41% of all individuals identified in the photo‐identification data were found at least once. The comparative approach proposed in this study to estimate individual spatial mixing can help quantify site fidelity patterns in wildlife populations and estimate its vulnerability to local stressors such as anthropogenic noise. [ABSTRACT FROM AUTHOR]

Diarrhetic shellfish poisoning (DSP) toxins and pectenotoxins (PTXs) produced by endemic species of Dinophysis, mainly D. acuta and D. acuminata, threaten public health and negatively impact the shellfish industry worldwide. Despite their socioeconomic impact, research on the environmental drivers of DSP outbreaks in the Chilean fjords is scanty. From 22 to 24 March 2017, high spatial–temporal resolution measurements taken in Puyuhuapi Fjord (Northern Patagonia) illustrated the short-term (hours, days) response of the main phytoplankton functional groups (diatoms and dinoflagellates including toxic Dinophysis species) to changes in water column structure. Results presented here highlight the almost instantaneous coupling between time–depth variation in density gradients, vertical shifts of the subsurface chlorophyll maximum, and its evolution to a buoyancy-driven thin layer (TL) of diatoms just below the pycnocline the first day. A second shallower TL of dinoflagellates, including Dinophysis acuta, was formed on the second day in a low-turbulence lens in the upper part of the pycnocline, co-occurring with the TL of diatoms. Estimates of in situ division rates of Dinophysis showed a moderate growth maximum, which did not coincide with the cell density max. This suggests that increased cell numbers resulted from cell entrainment of off-fjord populations combined with in situ growth. Toxin profiles of the net tow analyses mirrored the dominance of D. acuminata/D. acuta at the beginning/end of the sampling period. This paper provides information about biophysical interactions of phytoplankton, with a focus on Dinophysis species in a strongly stratified Patagonian fjord. Understanding these interactions is crucial to improv predictive models and early warning systems for toxic HABs in stratified systems. [ABSTRACT FROM AUTHOR]

Chilean Patagonia is confronted with several geohazards due to its tectonic setting, i.e., the presence of a subduction zone and numerous fault zones, e.g., the Liquiñe-Ofqui Fault Zone (LOFZ). This region has therefore been the subject of numerous paleoseismological studies. However, this study reveals that the seismic hazard is not limited to these large tectonic structures by identifying past fault activity near Coyhaique in Aysén Region. Mass-wasting deposits in Lago Pollux, a lake located ca. 15 km SW of this region's capital, were identified through analysis of reflection-seismic data and were linked to a simultaneous event recorded in nearby Lago Castor. Furthermore, a coeval ∼50 -year-long catchment response was identified in Aysén Fjord based on the multiproxy analysis of a portion of a sediment core. Assuming that this widely recognized event was triggered by an earthquake, ground-motion modeling was applied to derive the most likely magnitude and source fault. The model showed that an earthquake rupture along a local fault, in the vicinity of Lago Pollux and Lago Castor, with a magnitude of 5.6–6.8, is the most likely scenario. [ABSTRACT FROM AUTHOR]

Global estimates of the supply of dissolved and suspended materials to the ocean, in order to be relevant at either political or ecological scales, belie a finer-scale analysis necessary for understanding specific terrestrial-marine interactions. This is especially true for continental runoff to themarine critical zone of inland fjords and channels, where mechanisms, drivers, and predictions need to be elaborated in the context of changing land use and shifting climate forcing. In fjords in southwestern Patagonia, runoff from small coastal and large continental basins (~310 x103 km2), sourced from a diverse geography and wide climatic gradient (<150 - 6,000+ mm/year), correspond with a very low density of hydrological and water quality observations. Based on the recently developed regional runoff model (FLOW), we estimated the coastal freshwater discharges and characterized flowweighted sourcing (land use-cover type, climate, glaciers/geology, and soil province) for Pacific drainages from 41° to 56° south latitude. An estimated 692 km3/year (mean across 1979-2018), or 2% of worldwide total, is more than 85% of previous estimates for the much larger Pacific South American input. Based on limited water quality observations and inference from runoff sourcing, we predict general patterns of export for four groups of continental resources important for marine productivity, including: significant regional variation in flow seasonality, a N-S gradient in declining input of silicic acid and increased glacial input of sediment and iron, and potential shift in dissolved organic matter input sources from rainforest (potentially labile) to peatlands (refractory). Finally, we emphasize the temporal and spatial consequences of near-reference condition river runoff for marine ecosystem productivity and function in the Patagonian fjords, with specific recommendations for water quality standards and sustained monitoring for coupled river and marine ecosystems. [ABSTRACT FROM AUTHOR]

At the interface between the continental and oceanic domains, estuaries are essential components of the land–ocean aquatic continuum. These coastal ecosystems play a significant role in biogeochemical cycles, as they transform and export large amounts of terrigenous carbon and nutrients from rivers to marine waters. Because of this intense biogeochemical processing, they are significant ecosystems in terms of greenhouse gas exchange with the atmosphere. However, in spite of recent advances in remote sensing and the need for accurate estimates to calculate regional and global estuarine budgets, the global quantification of the estuarine spatial extent available for gas exchange has not been updated in over a decade and remains poorly constrained. This is due to the lack of a global extensive database, the diversity of estuaries, and the controversial definition of their boundaries. To address these challenges, a hybrid approach was developed that combines the surface areas of over 700 estuaries worldwide (extracted from the literature or calculated using geographical information systems) with a novel extrapolation method to provide type-specific regional estimates for 45 regions. The three estuarine types considered are ‘tidal systems and deltas’, ‘lagoons’, and ‘fjords’. The upscaling formula applied is determined and calibrated using data from several regions where an extensive survey of total estuarine surface areas was available. The new global estimate of 733,801 ± 39,892 km2 (mean ± 2 σ) is 31% lower than the previous global assessment. It also provides quantitative uncertainty estimates for regional and global estuarine surface areas as well as a breakdown between tidal systems and deltas (294,956 ± 30,780 km2), lagoons (179,946 ± 12,056 km2), and fjords (259,899 ± 22,328 km2). This decrease of the global estuarine surface area is related to the novel method used in this study and does not reflect a temporal trend. [ABSTRACT FROM AUTHOR]

Metal contamination in the Arctic region has increased over the years despite its remote and isolated location. Thus, to evaluate the bioavailable fractions of various metals and their effects on sediment-associated biota, the surface sediments from the fjords were analyzed for bulk concentration of metals and their speciation in different fractions. Metals concentrations were higher in the inner fjord region and decreased towards the outer fjord, supported by the terrigenous influence (TI%) calculated. Cr and Pb showed higher excess values attributed to their additional source other than the catchment rocks. So, to assess the metal-related ecological risk, the bulk concentration of metals was compared with Arctic sediment quality guidelines (ASQGs). Cr, Cd, and Pb concentrations were high, indicating potential adverse biological effects in the study. To avoid the risk of overestimation, metal speciation was conducted, showing that overall metal concentrations were higher in the residual fraction; however, higher concentrations of Mn in labile phases pose a moderate risk to the sediment-associated biota. Additionally, the population density of foraminifera in the sediments was calculated to assess the influence of bioavailable metal on benthic foraminifera. It was found that the presence of metals in bioavailable fractions affected the abundance of the foraminifera. However, no morphological abnormalities were observed in the species. [ABSTRACT FROM AUTHOR]

Climate change is increasingly predisposing polar regions to large landslides. Tsunamigenic landslides have occurred recently in Greenland (Kalaallit Nunaat), but none have been reported from the eastern fjords. In September 2023, we detected the start of a 9-day-long, global 10.88-millihertz (92-second) monochromatic very-long-period (VLP) seismic signal, originating from East Greenland. In this study, we demonstrate how this event started with a glacial thinning-induced rock-ice avalanche of 25 × 106 cubic meters plunging into Dickson Fjord, triggering a 200-meter-high tsunami. Simulations show that the tsunami stabilized into a 7-meter-high long-duration seiche with a frequency (11.45 millihertz) and slow amplitude decay that were nearly identical to the seismic signal. An oscillating, fjord-transverse single force with a maximum amplitude of 5 × 1011 newtons reproduced the seismic amplitudes and their radiation pattern relative to the fjord, demonstrating how a seiche directly caused the 9-day-long seismic signal. Our findings highlight how climate change is causing cascading, hazardous feedbacks between the cryosphere, hydrosphere, and lithosphere. [ABSTRACT FROM AUTHOR]

The article "Bestiarium Greenlandica: A Compendium of the Mythical Creatures, Spirits, and Strange Beings of Greenland" by Maria Bach Kreutzmann explores the mythical creatures of Greenland, including the Kliffak, Qivittoq, Tupilak, and Toornat. These creatures are deeply rooted in Greenlandic mythology and folklore, with unique characteristics and abilities. The author, Maria Bach Kreutzmann, has a passion for Greenlandic monsters and has written two books on the subject, delving into the rich cultural heritage of Greenland. [Extracted from the article]

The article "Everyday Arctics" in the Journal of Architectural Education features the photographic work of Inuuteq Storch, a Greenlandic artist. Storch's images capture everyday life in his hometown of Sisimiut, challenging exoticized portrayals of Greenland by outsiders. His projects, such as "Keepers of the Ocean" and "Porcelain Souls," offer intimate and unstaged glimpses into Greenlandic culture and identity. Storch's work has been exhibited internationally and published in several photobooks, showcasing the unique perspectives of life in Greenland. [Extracted from the article]

Zooplankton consumption of sinking aggregates affects the quality and quantity of organic carbon exported to the deep ocean. Increasing laboratory evidence shows that small particle‐associated copepods impact the flux attenuation by feeding on sinking particles, but this has not been quantified in situ. We investigated the impact of an abundant particle‐colonizing copepod, Microsetella norvegica, on the attenuation of the vertical carbon flux in a sub‐Arctic fjord. This study combines field measurements of vertical carbon flux, abundance, and size‐distribution of marine snow and degradation rates of fecal pellets and algal aggregates. Female M. norvegica altered their feeding behavior when exposed to aggregates, and ingestion rates were 0.20 μg C ind.−1 d−1 on marine snow and 0.11 μg C ind.−1 d−1 on intact krill fecal pellets, corresponding to 48% and 26% of the females' body carbon mass. Due to high sea surface abundance of up to ~ 50 ind. L−1, the population of M. norvegica had the potential to account for almost all the carbon removal in the upper 50 m of the water column, depending on the type of the aggregate. Our observations highlight the potential importance of abundant small‐sized copepods for biogeochemical cycles through their impact on export flux and its attenuation in the twilight zone. [ABSTRACT FROM AUTHOR]

Marine‐terminating glacier fjords play a central role in the transport of oceanic heat toward ice sheets, regulating their melt. Mixing processes near glacial termini are key to this circulation but remain poorly understood. We present new summer measurements of circulation and mixing near a marine‐terminating glacier with active sub‐glacial discharge. 65% of the fjord's vertical overturning circulation is driven by the buoyant plume, however we newly report intense vertical and horizontal mixing in the plume's horizontal spreading phase, accounting for the remaining 35%. Buoyant plume theory supports 2%–5% of total glacial melt. Thus, most of the heat associated with vertical overturing short‐circuits the glacial front. We find however that turbulence in the horizontal spreading phase redistributes the short‐circuited heat back into the surface waters of the near‐glacial zone. Our findings highlight the need for further research on the complex mixing processes that occur near the glacier terminus. Plain Language Summary: Melting of glacial ice is the single largest contributor to global sea‐level rise. Many glaciers flow into the ocean where the near‐vertical ice wall is bathed in relatively warm sea water. Freshwater from ice surface melting seeps down through cracks and crevasses in the glacier to be discharged at the base of the ice wall, many tens to hundreds of meters below the sea surface. This fresh water rises from the depths as a highly turbulent plume, drawing in and pushing upwards the surrounding seawater, eventually spreading horizontally as a mixture of fresh discharge and mixed‐in seawater. Few measurements exist in the dangerous zone where iceberg often calve. Using data from a robotic platform we show that the vertical rise and the horizontal spreading of fresh water both play important roles in the total ocean‐induced melting of the glacial face in this type of system. Key Points: Entrainment into the buoyant plume drives ∼65% of fjord vertical overturning circulationIntense turbulent mixing in the horizontal spreading phase of the plume drives the remaining ∼35%95%–98% of the heat in the rising plume short‐circuits the glacier, to be redistributed into glacial proximal waters by horizontal mixing [ABSTRACT FROM AUTHOR]

As a predatory fish that migrates between freshwater and marine environments, the sea trout (Salmo trutta) is important in linking these systems. This study investigated movement patterns of sea trout in a coastal fjord at the Swedish Skagerrak region from August 2018 to January 2019, using acoustic telemetry, while assessing these against environmental variables across different spatial and temporal scales. Six acoustic receivers were deployed in the fjord and a river, which flows into the upper reaches of the fjord, with the aim of detecting 20 sea trout that had been tagged with acoustic transmitters. Sea surface temperature and winds (east–west) affected movement patterns of the sea trout the most, while changes in atmospheric pressure were also important, but to a lesser extent. Sea surface temperature and atmospheric pressure both had a positive relationship with the number of detections, whereas stronger winds from the east (i.e. from land) resulted in more detections than stronger winds from the west (i.e. from the ocean). In addition, interesting diel (day–night) movement patterns were observed for some fish. A significant positive correlation was also discovered between the weight of the fish and the number of detections. This study offers insight in movements of sea trout that use coastal habitats and how environmental conditions can affect movement patterns in a fjord system. To further our understanding of sea trout movement patterns and connectivity, tracking from river, through fjord, out to sea and at a longer time scale with more variation in fish size would be valuable to understand more about the complex movement dynamics of this important species. [ABSTRACT FROM AUTHOR]

This study explores the synthesis of cyclopenta‐fused polyaromatic hydrocarbons (CP‐PAHs) via Pt‐catalyzed cyclization in water, focusing on the formation of fused pentagonal rings within heavily fused PAH frameworks. Utilizing platinum catalysts at lower temperatures (200‐260 °C) in water, led to the successful synthesis of singly cyclized CP‐PAHs. The reaction conditions facilitated the mono‐cyclization of substrates such as dibenzo[g,p]chrysene and its isomers, yielding the desired products while suppressing the formation of bis‐cyclized compounds. The use of Fe2O3 as an additive in conjunction with PtO2 was effective to suppress hydrogenation of the substrates and products. The products exhibited a redshift in UV‐visible absorption and photoluminescence bands due to a decrease in the HOMO−LUMO energy gap. These findings highlight the potential of Pt‐catalyzed cyclization for the controlled synthesis of CP‐PAHs, with implications for various applications in materials science. [ABSTRACT FROM AUTHOR]

High Latitude fjords can serve as sediment trap, bearing different type of proxies, from geochemical to micropaleontological ones, making them exceptional tools for paleoenvironmental reconstruction. However, some unconventional proxies can be present and can be used to depict a comprehensive and exhaustive interpretation of past changes. Here, studying a sediment core in Edisto Inlet (Ross Sea, Antarctica) we used irregular echinoid spines and ophiuroids (Ophionotus victoriae) ossicles to trace environmental changes throughout the last 3.6 kyrs BP. Irregular echinoids can serve as proxy for the organic matter content, while O. victoriae ossicles can be used as proxy for steady sea-ice cycle along with organic deposition events. O. victoriae release a high number of ossicles, making estimation about the population quite challenging; still, presence data, can be easily collected. By applying Generative Additive Models to the stratigraphical distribution of these data, we detected an environmental phase that was previously unnoticed by other traditional proxies: the Ophiuroid Optimum (2–1.5 kyrs BP). In conclusion, here we demonstrate how echinoderm presence can be used as a valuable source of information, while proving the potential of modelling binary data to detect long-term trend in Holocene stratigraphical records. [ABSTRACT FROM AUTHOR]

A nutrient distribution, such as that of phosphate (PO43-), ammonium (NH4+), nitrate (NO3-), dissolved silica (Si), total dissolved nitrogen (TN), and dissolved organic nitrogen (DON), together with dissolved organic carbon (DOC) and inorganic carbon (DIC), was investigated during a high-melting season in 2021 in the western Spitsbergen fjords (Hornsund, Isfjorden, Kongsfjorden, and Krossfjorden). Both the water column and the pore water were investigated for nutrients and dissolved carbon distribution and gradients. The water column concentrations of most measured parameters, such as PO43- , NH4+ , NO3- , Si, and DIC, showed significant changes among fjords and water masses. In addition, pore water gradients of PO43- , NH4+ , NO3- , Si, DIC, and DOC revealed significant variability between fjords and are likely substantial sources of the investigated elements for the water column. The reported dataset reflects differences in hydrography and biogeochemical ecosystem functions of the investigated western Spitsbergen fjords and may form the base for further modeling of physical oceanographic and biogeochemical processes within these fjords. All data discussed in this communication are stored in the Zenodo online repository at 10.5281/zenodo.11237340 (Szymczycha et al., 2024). [ABSTRACT FROM AUTHOR]

The seabed of the Gunneklev Fjord in south-eastern Norway is covered with exceptionally soft contaminated sediment containing mercury and dioxins. The sediments have an undrained shear strength less than 1 kPa and a variable thickness of up to 2.5 m. To reduce the potential for leaching of contaminants from these sediments, Hydro Energy AS developed a remediation plan involving capping of the sediment. Significant uncertainties are associated with the sediment's undrained shear strength and the cap thickness. An unfortunate combination of low shear strength and thick cap could cause slope failure (e.g. translational sliding of the sediment and/or bearing capacity failure (e.g. punching through). Failure, particularly slope failure, can cause spreading of the contaminants in the fjord causing serious consequences. This paper presents an assessment of the probability of slope failure associated with the contaminated sediment before and after the cap placement. Probability of bearing capacity failure is considered to have more local effect and is also discussed briefly. The study used the Monte Carlo method with random undrained shear strength and sediment thickness. The simulations show high slope failure probability when the seabed inclination was ≥ 1:50 combined with an average undrained shear strength ≤ 0.4 kPa. Based on the probabilistic analyses, a pilot field testing campaign was carried out (after this study) with 20-cm thickness cap in the "gentle" sloping area and 5-cm thickness in the "steep" areas to avoid causing a failure. The analyses were used to support evidence-based decision-making on the cap design and implementation for further field testing. [ABSTRACT FROM AUTHOR]

Climate change is causing widespread melting of land and sea ice in the Arctic, leading to an increase in freshwater input to the ocean. This may have an impact on ocean circulation, marine ecosystems, and biodiversity in the region. Our findings provide new insights into the summer hydrography conditions at proglacial fjord entrances along large parts of the east coast of Greenland. As most freshwater exits the Arctic Ocean through Fram Strait this study focuses on understanding the origin of spatial distribution of temperature and freshwater in the coastal waters in East Greenland. We find that Polar Water and the Atlantic Water variants (Eurasian Basin Atlantic Water/Subpolar Mode Water) dominate coastal waters north and south of Denmark Strait, respectively, and that coastal waters are influenced by advected meltwater from the Arctic Ocean, glacier meltwater and local precipitation. Combining hydrographic observations, water isotope data, and water source fraction analysis, we show that glacier meltwaters can be detected at fjord entrances and down to approximately 200 m. Integrated over the upper 200 m of the water column, glacial meltwater account for approximately 9%, precipitation for around 8% and Polar Water (including sea ice melt) for approximately 83% of the freshwater observed along the East Greenland coast. Below 200 m, Atlantic Water variants dominate the entire coastal section. The freshwater along East Greenland stays close to the coast and we could not detect any glacier meltwater at the slope. Plain Language Summary: The rapid warming of our planet has increased freshwater input to the Arctic Ocean. A major portion of this freshwater is exiting through Fram Strait. Also, meltwater runoff from tundra lands and glaciers connected to the Greenland ice sheet is an increasingly significant freshwater source to fjords. At present, incomplete observations exist regarding the spatial distribution of freshwater and its origin along East Greenland. Here we present results from a compressed survey of the pan‐East Greenland coastal system from the entrance of fjords. We describe the spatial distribution of water masses and source water fractions along East Greenland and their link to proglacial fjords. Key Points: Polar Water and Atlantic Water variants dominate East Greenland coastal waters north and south of Denmark Strait, respectivelyGlacier meltwater cannot be detected at the slope and most Polar Water, meteoric water, and glacier meltwater are confined to the coastAlong the coast, glacial meltwater account for ∼9%, precipitation for ∼8% and Polar Water (including sea ice melt) for ∼83% of the freshwater [ABSTRACT FROM AUTHOR]

Kongsfjorden, an Arctic fjord in Svalbard, is largely influenced by the West Spitsbergen Current (WSC), transporting warm and salty Atlantic Water (AW) into the Arctic region. Despite the geostrophic control preventing AW from entering the fjord in winter, AW intrusions occasionally occur during energetic local wind events in this season. However, recent intrusions remain poorly characterized, and the underlying mechanism(s) and large‐scale precursors are only partly understood. This study uses in‐situ oceanographic and atmospheric measurements, alongside reanalysis data covering 2011–2020, to describe recent wintertime AW intrusions in Kongsfjorden. By discerning common traits in the observed events, the main triggering factors and controls of the phenomenon are described. Our results indicate that AW intrusions are typically triggered by wind reversals over the shelf, consisting of the sudden transition from a strong southerly to a northerly circulation linked to the setup and damping of a high‐pressure anomaly over the Barents Sea. Ocean density is a critical preconditioning factor influencing the nature of the intrusion: when fjord waters exhibit a lower density compared to WSC waters, wind reversals induce AW intrusions by upwelling; in contrast, when fjord waters present higher or similar densities compared to WSC waters, reversals force AW inflows near the surface or at intermediate depths, respectively. Another mechanism was observed only in winter 2014: southerly winds prevailed for 2 months, transporting surface AW from the WSC into the fjord, promoting its intrusion near the surface, on top of denser local waters. Plain Language Summary: Kongsfjorden, an Arctic fjord in Svalbard, is largely influenced by the WSC, which carries warm and salty Atlantic Water (AW) into the Arctic region. Occasionally, the fjord experiences sudden wintertime warming events due to intrusions of AW, whose underlying mechanism(s) and large‐scale precursors remain only partly described. By examining events observed in the 2011–2020 decade, we found that changes in wind direction typically trigger such intrusions, precisely when energetic winds from the south are followed by winds from the north. These episodes lead to abrupt warming events, but AW intrusions occur only when the density of the fjord is lower than that of the WSC. When fjord waters have a similar or larger density than WSC waters, wind events generate AW inflows at intermediate or near‐surface depths, respectively. Hence, the atmosphere triggers the AW intrusion, but its dynamics are determined by oceanic conditions, acting as a critical preconditioning factor. Additionally, a second intrusion mechanism was observed: prolonged winds from the south force AW from the WSC to intrude in the near‐surface layers of the fjord, on top of denser waters. Key Points: Sudden winter intrusions of Atlantic Water in Kongsfjorden are typically triggered by abrupt reversals of local meridional windsThe dynamics of the intrusions are determined by the density difference between fjord and Atlantic watersThe peculiar intrusion of winter 2014 was triggered by long‐lasting southerly winds, transporting warm surface waters toward the fjord [ABSTRACT FROM AUTHOR]

Purpose: Viruses are the largest genetic repository and most diverse host-associated replicating organisms in a wide range of ecosystems in the entire biosphere. Although playing crucial roles in numerous processes such as nutrient cycles, viral shunt, and population control within marine ecosystems, viral communities continue to be the least explored biological entities, particularly in extreme marine habitats. Therefore, details about the viral diversity and their metabolic potential from Arctic sediments has great importance. Methods: Sediment samples were collected from two Arctic fjords, Kongsfjorden and Krossfjorden, in Svalbard. Viral nucleic acids were extracted from both fjord sediments after a pre-processing step. Illumina Novaseq based shotgun sequencing was performed and bioinformatic analysis was done to explore viral communities and their functional potential. Results: An array of DNA and RNA viruses especially bacteriophages along with viruses infecting algae, plants, molluscs, shrimps, fishes, amphibians, reptiles, birds, humans, and other mammals were detected from both fjords. The double-stranded DNA viruses were the most abundant (Siphoviridae, Podoviridae, Myoviridae, and Phycodnaviridae), followed by single-stranded DNA (Inoviridae) and RNA (Retroviridae and Betaflexiviridae) viruses from both metavirome. Functional analysis explored genes encoding virus structures, enzymes for phage replication, integration and excision and proteins related to phage regulation of gene expression. Conclusions: Fjord metavirome analysis revealed the occurrence of virus groups endemic to Arctic freshwater and marine habitats along with an extra pool of unclassified or unassigned virus reads. Viruses infecting a variety of bacterial groups, and other higher trophic levels in fjord environments were explored. Functional annotation revealed the abundance of phage-related structural genes and metabolic genes. Comparative analysis revealed the abundance of dsDNA viruses from Caudovirales (Myoviridae, Podoviridae and Siphoviridae) in all the analysed Arctic samples in different proportions. The present study enhances our understanding of viral diversity and their metabolic potential in Arctic fjord sediments. [ABSTRACT FROM AUTHOR]

Little is known about the role of remote and sparsely populated Arctic coastal zones in the microplastic cycle. Distribution of microplastics was studied in the Svalbard fjords in June – July 2022 with the main goal of assessing rivers’ role in the fate of microplastic in Arctic coastal waters. Surface microplastics (0 – 20 cm depth, 500 – 5000 µm size) were sampled with a neuston net in triplicate per study site in parallel with sampling of subsurface microplastics with a pump system (1.5 m depth, 100 – 5000 µm size). The central part of Isfjorden and its several branches covering populated and unpopulated fjords were studied; the sampling was conducted during an intense riverine discharge in all studied sites. Maximum abundance of surface microplastics (71,400 items/km2 or 0.19 iterms/m3, 0.19 mg/m3) was found along the river plume border in the middle of populated Adventfjorden indicating importance of both local sources and surface hydrodynamics in the formation of microplastics accumulation hotspots. All other unpopulated fjords were free of the floating on the sea surface microplastics as river discharge prevented transport of microplastics inside the fjords. The highest concentration of subsurface microplastics was found in the central part of Isfjorden and the lowest – in river plume waters, which also indicates the removal of microplastics from the inner part of fjords during an intensive river discharge. Our results may suggest that Arctic rivers flowing through unpopulated areas bring clean water and thereby reduce level of microplastic pollution in the coastal waters. In contrast to the rest of the world’s ocean, rivers are not the main source of microplastic pollution in the Arctic Ocean.

This comprehensive study examines primary production (PP) within the Spitsbergen fjords, Hornsund, and Kongsfjord, over a 25‐year period (1994–2019), across 45 stations and 348 incubation levels at various depths. PP and hydrological parameters were measured at 28 sampling stations in Kongsfjorden and 17 in Hornsund, with the locations of "Glacier," "Inner," and "Outer" zones defined to reflect the varying influence of glacial meltwater. Our study revealed spatial and temporal variability in PP, both at the surface and within the water column with very high depth resolution. The highest PP values were observed in the Glacier and Inner zones of Hornsund, particularly in the water layer up to 3 m depth, exceeding 20 mgC m−3 h−1. A notable decline in PP with increasing depth was observed in both fjords, with the Glacier zones displaying the highest productivity at the surface. The study also highlights the influence of glacial meltwater on surface water conditions, affecting the PP in the upper layers of both fjords. The observed gradient in the depth of maximum PP toward the mouth of the fjord varied between the two fjords, with Kongsjord displaying more dynamic variations. The spatial distribution of integrated primary production (Pi) suggested lower productivity in the glacial regions, likely due to light limitation caused by high concentrations of mineral particulate matter. The values of Pi were considerably higher in Hornsund, approximately twice as high overall, with specific emphasis on the Glacier and Inner zones where Pi values were about 6.5 and 2.5 times higher, respectively, when compared to those observed in Kongsfjord. [ABSTRACT FROM AUTHOR]

The dinoflagellate Alexandrium catenella is a well-known paralytic shellfish toxin producer that forms harmful algal blooms, repeatedly causing damage to Chilean coastal waters. The causes and behavior of algal blooms are complex and vary across different regions. As bacterial interactions with algal species are increasingly recognized as a key factor driving algal blooms, the present study identifies several bacterial candidates potentially associated with Chilean Alexandrium catenella. This research narrowed down the selection of bacteria from the Chilean A. catenella culture using antibiotic treatment and 16S rRNA metabarcoding analysis. Subsequently, seawater from two Chilean coastal stations, Isla Julia and Isla San Pedro, was monitored for two years to detect Alexandrium species and the selected bacteria, utilizing 16S and 18S rRNA gene metabarcoding analyses. The results suggested a potential association between Alexandrium species and Spongiibacteraceae at both stations. The proposed candidate bacteria within the Spongiibacteraceae family, potentially engaging in mutualistic relationships with Alexandrium species, included the genus of BD1-7 clade, Spongiibbacter, and Zhongshania. [ABSTRACT FROM AUTHOR]

Most inhabitants of the Arctic live near the coastline, which includes fjord systems where socio-ecological coupling with coastal communities is dominant. It is therefore critically important that the key aspects of Arctic fjords be measured as well as possible. Much work has been done to monitor temperature and salinity, but in-depth knowledge of the light environment throughout Arctic fjords is lacking. This is particularly problematic knowing the importance of light for benthic ecosystem engineers such as macroalgae, which also play a major role in ecosystem function. Here we document the creation and implementation of a high-resolution (∼50 –150 m) gridded dataset for surface photosynthetically available radiation (PAR), diffuse attenuation of PAR through the water column (KPAR), and PAR available at the seafloor (bottom PAR) for seven Arctic fjords distributed throughout Svalbard, Greenland, and Norway during the period 2003–2022. In addition to KPAR and bottom PAR being available at a monthly resolution over this time period, all variables are available as a global average, annual averages, and monthly climatologies, with standard deviations provided for the latter two. Throughout most Arctic fjords, the interannual variability of monthly bottom PAR is too large to determine any long-term trends. However, in some fjords, bottom PAR increases in spring and autumn and decreases in summer. While a full investigation into these causes is beyond the scope of the description of the dataset presented here, it is hypothesized that this shift is due to a decrease in seasonal ice cover (i.e. enhanced surface PAR) in the shoulder seasons and an increase in coastal runoff (i.e. increased turbidity and decreased surface PAR) in summer. A demonstration of the usability of the dataset is given by showing how it can be combined with known PAR requirements of macroalgae to track the change in the potential distribution area for macroalgal habitats within fjords with time. The datasets are available on PANGAEA at 10.1594/PANGAEA.962895 (Gentili et al., 2023a) and 10.1594/PANGAEA.965460 (Gentili et al., 2024). A toolbox for downloading and working with this dataset is available in the form of the FjordLight R package, which is available via CRAN (Gentili et al., 2023b, 10.5281/zenodo.10259129) or may be installed via GitHub: https://face-it-project.github.io/FjordLight (last access: 29 April 2024). [ABSTRACT FROM AUTHOR]

Glacial fjord circulation determines the import of oceanic heat to the Greenland Ice Sheet and the export of ice sheet meltwater to the ocean. However, limited observations and the presence of both glacial and coastal forcing—such as coastal‐trapped waves—make uncovering the physical mechanisms controlling fjord‐shelf exchange difficult. Here we use multi‐year, high‐resolution, realistically forced numerical simulations of Sermilik Fjord in southeast Greenland to evaluate the exchange flow. We compare models, with and without a plume, to differentiate between the exchange flow driven by shelf variability and that driven by subglacial discharge. We use the Total Exchange Flow framework to quantify the exchange volume transports. We find that a decline in offshore wind stress from January through July drives a seasonal reversal in the exchange flow increasing the presence of warm Atlantic Water at depth. We also find that including glacial plumes doubles the exchange flow in the summer. Our results show that the plume‐driven circulation is more effective at renewal with a flushing time 1/3 that of the shelf‐driven circulation near the fjord head. Plain Language Summary: Glacial fjords are narrow coastal inlets with a glacier at the landward edge. The flow of water within fjords plays a crucial role in exchanging heat and freshwater between the glacial ice and ocean. The circulation of water is driven, in part, by melting at the ice surface which falls through cracks in the ice and enters the fjord near the sea bed. The meltwater is less dense than ocean water causing it to rise as a plume before leaving the fjord close to the surface. However, fjord circulation is also impacted by storms close to the coast and offshore wind. We used a model of a fjord in Greenland to isolate and study the effects of coastal winds and meltwater on fjord circulation. Our model experiments reveal that weaker than average winds can lead to warmer water within the fjord. Also, we find that the circulation speed doubles with the addition of meltwater and a plume. These results increase our understanding of fjord circulation. Key Points: We present a set of realistically forced, multi‐year numerical simulations of Sermilik Fjord in GreenlandThe shelf‐driven circulation is tied to along‐shelf wind stress and drives a reversal in the exchange flow as winds intensify in SeptemberThe plume‐driven circulation is more effective at renewal with a flushing time 1/3 that of the shelf‐driven circulation near the fjord head [ABSTRACT FROM AUTHOR]

The exchange of heat and freshwater between glaciers and the ocean is dictated by the circulation in glacial fjords and ice shelf cavities. Therefore, our ability to estimate and predict these fluxes depends on our understanding of the circulation mechanisms inside these polar estuaries. Here, we use an exceptionally long observational data set (8+ years) to develop and validate a high‐resolution realistic numerical model of Milne Fiord (Nunavut, Canada), a glacial fjord with an ice shelf at its mouth. Model results show the circulation inside Milne Fiord from 2011 to 2019 is highly three‐dimensional and unsteady. Three distinct circulation modes are identified (eddy, front, barotropic). The shifts between circulation modes are driven by density variations in the offshore coastal current, which restrict vertical stretching, allowing (or not) the coastal current to develop sufficient relative vorticity to enter the fjord. The unsteadiness of the system results in an overturning estuarine circulation with mean velocities ∼50 times smaller than the instantaneous field. Moreover, analysis of the model outputs suggest that at least 2 years of simulation are needed to yield reliable average heat flux estimates in this environment. This work highlights the value of combining long term (>1 year) observations with numerical modeling. This allowed us to uncover the spatial and temporal variability of the system, which impacts how heat and freshwater fluxes can be reliably estimated. Plain Language Summary: Fjords and bays where glaciers end their course in the ocean are common in the Arctic and in Antarctic. The circulation and the interactions between the ocean and glaciers in these polar estuaries has implications for ice loss and sea level rise. It is therefore important to understand the ocean dynamics in glacial fjords (a fjord with a marine terminating glacier) and ice shelf cavities (a water column overlain by the floating extension of a glacier or ice shelf) in order to quantify the impact of the ocean forcing on glaciers. In this study, we use a numerical model to reproduce the ocean conditions in Milne Fiord, a glacial fjord with an ice shelf on the north coast of Ellesmere Island, Nunavut, Canada. The model is validated with in situ observations. The results show that although the velocities are small in Milne Fiord (around 2 cm/s), the circulation is very dynamic. In fact, the circulation pattern is continually changing in response to offshore density variations (no steady‐state). This is problematic for estimating the heat exchange between the ocean and the glacier, because it means limited observations cannot be readily extrapolated in time and space. Key Points: A high‐resolution numerical model of a glacial fjord with an ice shelf (Milne Fiord) was run for 8.3 years and validated with observationsMilne Fiord circulation is highly variable across space and time and switches between three different circulation modes (no steady‐state)The variability of the circulation highlights the need for long term observational programs combined with (validated) numerical models [ABSTRACT FROM AUTHOR]

The hydrographic variability in the fjords of Svalbard significantly influences water mass properties, causing distinct patterns of microbial diversity and community composition between surface and subsurface layers. However, surveys on the phytoplankton-associated bacterial communities, pivotal to ecosystem functioning in Arctic fjords, are limited. This study investigated the interactions between phytoplankton and heterotrophic bacterial communities in Svalbard fjord waters through comprehensive eDNA metabarcoding with 16S and 18S rRNA genes. The 16S rRNA sequencing results revealed a homogenous community composition including a few dominant heterotrophic bacteria across fjord waters, whereas 18S rRNA results suggested a spatially diverse eukaryotic plankton distribution. The relative abundances of heterotrophic bacteria showed a depth-wise distribution. By contrast, the dominant phytoplankton populations exhibited variable distributions in surface waters. In the network model, the linkage of phytoplankton (Prasinophytae and Dinophyceae) to heterotrophic bacteria, particularly Actinobacteria, suggested the direct or indirect influence of bacterial contributions on the fate of phytoplankton-derived organic matter. Our prediction of the metabolic pathways for bacterial activity related to phytoplankton-derived organic matter suggested competitive advantages and symbiotic relationships between phytoplankton and heterotrophic bacteria. Our findings provide valuable insights into the response of phytoplankton-bacterial interactions to environmental changes in Arctic fjords. [ABSTRACT FROM AUTHOR]

In recent decades, the Greenland ice sheet has been losing mass through glacier retreat and ice flow acceleration. This mass loss is linked with variations in submarine melt, yet existing ocean models are either coarse global simulations focused on decadal‐scale variability or fine‐scale simulations for process‐based investigations. Here, we unite these scales with a framework to downscale from a global state estimate (15 km) into a regional model (3 km) that resolves circulation on the continental shelf. We further downscale into a fjord‐scale model (500 m) that resolves circulation inside fjords and quantifies melt. We demonstrate this approach in Scoresby Sund, East Greenland, and find that interannual variations in submarine melt at Daugaard‐Jensen glacier induced by ocean temperature variability are consistent with the decadal changes in glacier ice dynamics. This study provides a framework by which coarse‐resolution models can be refined to quantify glacier submarine melt for future ice sheet projections. Plain Language Summary: Over the past several decades, the Greenland ice sheet has been losing ice and contributing to sea‐level rise. About half of this ice loss is induced by melt that occurs where glaciers meet the ocean. Using coarse‐scale ocean models that simulate circulation around the globe, previous studies have noted a strong link between ocean temperature and enhanced glacier ice loss. However, due to the small scale of Greenland's fjords, coarse models are unable to directly quantify circulation in these fjords and melt on submerged glaciers. In this study, we develop a new framework to "zoom in" on a fjord, using high‐resolution models driven by larger coarse‐resolution models. In this approach, we simulate melt on one of Greenland's biggest glaciers and find that periods of higher melt coincide with more ice loss as observed from satellites. Since this framework is adaptable to other regions, it could also be used to simulate melt on other glaciers and support estimates of future sea‐level rise. Key Points: Subsurface temperature variability is simulated in a narrow fjord network using regional models downscaled from a global state estimateModeled increases in ocean melt at Daugaard‐Jensen glacier coincide with the onset of acceleration in 2005 and retreat and thinning in 2011Model variations in shelf‐to‐fjord ocean properties match with observations, providing a basis to estimate ocean forcing in ice projections [ABSTRACT FROM AUTHOR]

There is increasing evidence that holocarpic oomycetes, i.e., those converting their entire vegetative thallus into zoospores upon maturation, are a phylogenetically diverse group in both freshwater and marine ecosystems. Most of the known holocarpic oomycete species diverge before the main split of Peronosporomycetes and Saprolegniomycetes and are, thus, termed as early-diverging oomycetes. In environmental sequencing studies, it was revealed that of the early-diverging genera especially Sirolpidium, Miracula, and Diatomophthora are widespread. As in these studies especially the Arctic Ocean seemed to harbor many undiscovered species, sampling was conducted at the Blávík research station on Fáskrúðsfjörður in the East Fjords of Iceland, where there is both an influence from the Arctic Ocean and the North Atlantic. During the screening for infected diatoms, a parasitoid was found in the marine diatom genus Melosira, which is one of the most abundant genera in arctic ecosystems. Molecular phylogenetics and morphological characterization revealed that the parasitoid belonged to the genus Miracula and corresponded to one of the lineages previously found in single-cell sequencing. Thus, the current study both contributes to the knowledge of the genus Miracula and the increasing diversity of the genus suggests that the many linages found in environmental sequencing which can still not be associated with known species might represent actual species to be discovered in future studies. [ABSTRACT FROM AUTHOR]

The Sanak-Baranof belt includes a series of near-trench plutons that intrude the outboard Chugach-Prince William terrane over ~2200 km along the southern Alaskan margin. We present new petrological, geochronological, and geochemical data for comagmatic microgranitoid enclaves and granitoid rocks from the Crawfish Inlet (ca. 53-47 Ma) and Krestof Island (ca. 52 Ma) plutons on Baranof and Krestof Islands, as well as the Mount Stamy (ca. 51 Ma) and Mount Draper (ca. 54-53 Ma) plutons and associated mafic rocks that intrude the Boundary block at Nunatak Fiord near Yakutat, Alaska, USA. These data suggest that intrusion of the Sanak-Baranof belt plutons is actually a tale of two distinct belts: a western belt with crystallization ages that young systematically from west to east (63-56 Ma) and an eastern belt with crystallization ages ranging from 55 to 47 Ma, but with no clear age progression along the margin. Hf isotope analyses of magmatic zircon from the western Sanak-Baranof belt become increasingly evolved toward the east with εHft = 9.3 ± 0.7 on Sanak Island versus εHft = 5.1 ± 0.5 for the Hive Island pluton in Resurrection Bay. The Hf isotope ratios of eastern Sanak-Baranof belt rocks also vary systematically with age but in reverse, with more evolved ratios in the oldest plutons (εHft = +4.7 ± 0.7) and more primitive ratios in the youngest plutons (εHft = +13.7 ± 0.7). We propose that these findings indicate distinct modes of origin and emplacement histories for the western and eastern segments of the Sanak-Baranof belt, and that the petrogenesis of eastern Sanak-Baranof belt plutons (emplaced subsequent to 57-55 Ma) was associated with an increasing mantle component supplied to the youngest eastern Sanak-Baranof belt magmas. These plutons reveal important information about offshore plate geometries and a dynamic period of plate reorganization ca. 57-55 Ma, but a clearer picture of the tectonic setting that facilitated these Sanak-Baranof belt intrusions cannot be resolved until the magnitude and significance of lateral translation of the Chugach-Prince William terrane are better understood. [ABSTRACT FROM AUTHOR]

Predator–prey interactions in time and space determine stock productivity, making them an important consideration when managing marine resources, rebuilding stocks or considering reopening a fishery.We analysed fine‐scale diet data from surveys conducted in 2009–2010 and 2018–2019 in three fjords in northern Norway with geostatistical models investigating how predation varied in space, time and between predator species. Our focus prey species was northern shrimp (Pandalus borealis), valuable both as a commercial resource and a major food source for other important species like Atlantic cod (Gadus morhua).Diet composition of fish predators differed clearly between fjords. While predator species and size were good predictors of shrimp predation, the relationships with bathymetry, prey density and geospatial variables were complex.Our study indicates that predation of forage species, such as shrimp, varies spatially in heterogenous fjord ecosystems. Shrimp consumption was not highest in the fjord with highest predator density, indicating a higher dependency of cod on shrimp in specific areas.Realized predation is a complex combination of predator and prey densities and predator ecology that differed in each of the three fjords.Synthesis and applications. Ignoring spatial variations in predator–prey interactions may lead to an inaccurate perception of stock productivity, suboptimal management and possibly unsustainable management targets. We recommend spatially explicit assessment and management for fish stocks where predator–prey interactions vary substantially in space, such as fjords and reefs. [ABSTRACT FROM AUTHOR]

On 16 May 2021, a storm petrel was photographed on a pelagic trip in the Benguela Current off Cape Town, South Africa, exhibiting the diagnostic features of Pincoya Storm Petrel Oceanites pincoyae. This sighting occurred far from other records, the closest being approximately 7500 km away. The record, therefore, requires us to reassess our understanding of the movements and ecology of Pincoya Storm Petrel, which was previously known only from shallow waters in fjords and adjacent seas in south-central Chile. Pincoya Storm Petrel is considered Data Deficient by the International Union for Conservation of Nature (IUCN), the breeding range remains unknown, and the population was estimated to number only around 3000 individuals. While Pincoya Storm Petrel is recognised as a valid species by the International Ornithological Congress (IOC), eBird/Clements checklists, and the South American Classification Committee, its taxonomic status has been questioned. This sighting of a bird with all the features of Pincoya Storm Petrel distant from previous sightings, and in a markedly different ecological setting, may lead us to re-evaluate our understanding of species limits and phenotypic variation in Oceanites storm petrels. Further research to collect phenotypic, phylogenetic, and phenological data will allow us to re-examine species boundaries in Oceanites and enhance our understanding of this fascinating genus. [ABSTRACT FROM AUTHOR]

Although knowledge of Arctic benthic biodiversity has increased considerably in recent decades, some regions, such as Northeast Greenland, remain poorly studied. The aim of this study was to complement a previous macrofaunal inventory carried out in Young Sound, a High-Arctic fjord in this region (74°N). We sampled shallow benthic assemblages along a small inner/outer fjord gradient, including one station previously prospected two decades ago and three new stations. This sampling strategy revealed highly diversified benthic assemblages (166 species identified on a total sampling area of 1.32 m2), which considerably increases the number of species recorded for the fjord (i.e. 225 species vs 100 previously recorded). The outermost station was dominated in abundance by various assemblages of bivalves, while the middle stations showed greater species evenness, including numerous species of polychaetes, bivalves and crustaceans. The innermost station was dominated by ostracods, gammarid amphipods and tube-dwelling polychaetes. Overall, benthic assemblages varied little between the four stations and the transect as a whole exhibited characteristics typical of outer fjord habitats, reflecting the rather moderate impact of meltwater inputs in this part of the fjord. Finally, trophic plasticity and omnivory were observed in most of the recorded macrobenthic species, highlighting the adaptability of these species to low trophic availability in the ecosystem. Future biodiversity studies will need to explore the innermost and deepest areas to provide a more comprehensive inventory and understanding of the influence of environmental conditions on the structure and functioning of Young Sound benthic habitats. [ABSTRACT FROM AUTHOR]

In 1980, reports of deep-sea jellyfish blooms in Norwegian fjords led researchers to investigate the problem. The helmet jellyfish, Periphylla periphylla, has since migrated far north into Arctic waters. This paper examines what happened when the jellyfish blooms were noticed in 1980 from a historical and ethnographic perspective. It traces four research projects and business ideas that proposed solutions to the jellyfish problem and asks how they are representative of the ways in which humans meet the challenges of anthropogenic climate change. The paper concludes that the jellyfish problem was met with a "techno-fix" attitude that sought to "turn a problem into a resource", which eventually leads to what Julia Livingston has termed "self-devouring growth". In a final outlook, the article asks how we can engage with questions of conservation from a humanities perspective and concludes that the jellyfish story can help us to ask questions about "conservation for whom". [ABSTRACT FROM AUTHOR]