Canadian Arctic Research Articles

Carbon dynamics in an alluvial fan in the eastern Canadian Arctic

Alluvial fans are common features of mountainous landscapes in circumpolar regions and are characterized by a suit of hillslope processes that drive sediment distribution. At present there is little known about the biogeochemistry of these systems. Thus, this study aimed to understand alluvial fan soil carbon (C) dynamics. Surface and permafrost soil was retrieved in the apex, mid-section, and foot of a fan on Bylot Island in the Canadian Arctic. Soil characteristics such as grain size distribution, ice content and major ions, electric conductivity, as well as total C and nitrogen (N) contents were determined. Moreover, soil organic carbon (SOC) pools were assessed using density fractionation in combination with acid hydrolysis. Despite the strong influence of hillslope processes on physical sediment characteristics, hillslope location had no effect on SOC and N stocks. However, fractionation analysis showed that hillslope processes facilitate the degradation of soil C prior to its burial and integration into permafrost soil, where over 90% of the SOC pool associated with the mineral-fraction is resistant to degradation. Hence, SOC pools at the foot of alluvial fans may be considered relatively stable.

Living under Arctic kelp forests: linking soft-bottom communities to kelp cover in the Canadian Arctic

Kelp forests are dominant habitats along Canadian Arctic coastlines. While their extent and productivity are expected to change dramatically due to global warming, their role in supporting Arctic coastal biodiversity remains poorly explored. Leveraging an extensive data set encompassing core samples, video transects, and environmental data, this study explores the patterns and drivers of benthic diversity, particularly focusing on kelp cover, across 4 Eastern Canadian Arctic regions. We show that the widespread soft bottoms in many subtidal coastal Arctic areas are associated with high densities of the kelp Saccharina latissima, often growing in mixed stands with Laminaria solidungula and Alaria esculenta. These kelps enhance the diversity of invertebrate communities thriving in the sediment below, increasing densities in specific groups and promoting subsurface feeding activity. Interregional comparisons indicate that high turbidity conditions typically lead to low macroalgal cover and low invertebrate richness, whereas extensive sea ice cover can favor high macroalgal abundance and unique diverse communities. Conditions of intermediate open-water duration and high water clarity support tall kelp forests, hosting approximately 70% of local rare taxa. Based on these surveys, we provide a list of Arctic invertebrate taxa according to their level of selectivity for kelp forests as habitats. Despite variation among regions, kelp forests enhance biodiversity and drive unique benthic communities in the Canadian Arctic. Due to their ecological significance and potential vulnerability, we recommend efforts to integrate kelp forests into marine protected areas and minimize human-induced damaging activities within or near these habitats.

Oceanic anoxic event 3 in Arctic Canada—Arc volcanism and ocean fertilization drove anoxia

The global extent of the Late Cretaceous oceanic anoxic event 3 (OAE 3) remains uncertain. It is not considered to have extended into the Boreal Realm. To test this, we examined Late Cretaceous organic- and metal-rich black mudstones of the Smoking Hills Formation in Arctic Canada. New high-precision U-Pb zircon ages indicate that deposition of the Smoking Hills Formation (88.535−78.230 Ma) was temporally coincident with OAE 3, indicating a much broader global expression of this event than previously thought. OAE 3 was likely manifest throughout the proto−Arctic Ocean (now Arctic Canada). Abundant bentonite layers and cryptotephra within the Smoking Hills Formation have rare earth element (REE) patterns that are consistent with ashfall derived from Cretaceous arc volcanism. Anomalously high organic matter content in the Smoking Hills Formation, as compared to underlying and overlying units, suggests that ocean fertilization led to enhanced productivity and metal drawdown. A peak in arc volcanism may have been a key driver of the OAE 3 event. We also explored the potential use of cadmium as a geochemical marker of volcanism and show that high volcanogenic metal loading could affect the use of Cd and other proxies for marine productivity (e.g., Zn, Cu).

Rock avalanches in northeastern Baffin Island, Canada: understanding low occurrence amid high hazard potential

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.

Modeling pan-Arctic seasonal and interannual landfast sea ice thickness and snow depth between 1979 and 2021

ABSTRACT Landfast sea ice (LFSI) is sensitive to local climate change, making it an important component of the cryosphere system. In this study, the LFSI around the pan-Arctic domain was simulated from 1979 to 2021 using a well-validated snow and ice thermodynamic model (HIGHTSI) under the framework of the Fast Ice Prediction System (FIPS), forced by the ERA5 reanalysis. The simulation results agree well with the in-situ observations in the Canadian Arctic, with a mean error of −0.06 ± 0.29 m for ice thickness and −0.04 ± 0.12 m for snow depth. A decrease of −2.8 ± 0.4 cm/10a in thickness and −16.2 ± 1.5 km3/a in volume for the Arctic LFSI was modeled during this period. There was significant spatial variability among the different domains, with the fastest decline found in the Vilkitsky Strait. The modeled snow depth shows large interannual and spatial variations, which was confirmed by other modeling results. The spatiotemporal variations in both air temperature and precipitation are the driving factors for the multi-decadal variations in LFSI thickness. The decreasing air temperature during the 2010s aligned with a slower thickness decrease and a slight volume increase for LFSI, which agreed with the pan-Arctic sea ice pattern.

Genomic characterization and virulence gene profiling of Erysipelothrix rhusiopathiae isolated from widespread muskox mortalities in the Canadian Arctic Archipelago

BackgroundMuskoxen are important ecosystem components and provide food, economic opportunities, and cultural well-being for Indigenous communities in the Canadian Arctic. Between 2010 and 2021, Erysipelothrix rhusiopathiae was isolated from carcasses of muskoxen, caribou, a seal, and an Arctic fox during multiple large scale mortality events in the Canadian Arctic Archipelago. A single strain (‘Arctic clone’) of E. rhusiopathiae was associated with the mortalities on Banks, Victoria and Prince Patrick Islands, Northwest Territories and Nunavut, Canada (2010–2017). The objectives of this study were to (i) characterize the genomes of E. rhusiopathiae isolates obtained from more recent muskox mortalities in the Canadian Arctic in 2019 and 2021; (ii) identify and compare common virulence traits associated with the core genome and mobile genetic elements (i.e. pathogenicity islands and prophages) among Arctic clone versus other E. rhusiopathiae genomes; and iii) use pan-genome wide association studies (GWAS) to determine unique genetic contents of the Arctic clone that may encode virulence traits and that could be used for diagnostic purposes.ResultsPhylogenetic analyses revealed that the newly sequenced E. rhusiopathiae isolates from Ellesmere Island, Nunavut (2021) also belong to the Arctic clone. Of 17 virulence genes analysed among 28 Arctic clone isolates, four genes – adhesin, rhusiopathiae surface protein-A (rspA), choline binding protein-B (cbpB) and CDP-glycerol glycerophosphotransferase (tagF) – had amino acid sequence variants unique to this clone when compared to 31 other E. rhusiopathiae genomes. These genes encode proteins that facilitate E. rhusiopathiae to attach to the host endothelial cells and form biofilms. GWAS analyses using Scoary found several unique genes to be overrepresented in the Arctic clone.ConclusionsThe Arctic clone of E. rhusiopathiae was associated with multiple muskox mortalities spanning over a decade and multiple Arctic islands with distances over 1000 km, highlighting the extent of its spatiotemporal spread. This clone possesses unique gene content, as well as amino acid variants in multiple virulence genes that are distinct from the other closely related E. rhusiopathiae isolates. This study establishes an essential foundation on which to investigate whether these differences are correlated with the apparent virulence of this specific clone through in vitro and in vivo studies.

Climate change and Arctic charr (Salvelinus alpinus) in North America: modelling possible changes in range with different climate scenarios and interspecific interactions

AbstractOne of the greatest challenges for researchers today is understanding climate-change impacts on fish populations, particularly in vulnerable and understudied ecosystems such as the Canadian Arctic. Among other impacts, northern fishes will undergo thermal stress as atmospheric and sea surface temperatures are projected to rise globally. Models that consider how both environmental factors such as temperature and potential species interactions will impact population extirpation and species’ range contraction can help project the future distribution of a species in the face of a warming climate. Here, we investigate the climate-change impacts of rising temperatures and the potential northward distributional shift of brook charr (Salvelinus fontinalis) on Arctic charr (Salvelinus alpinus), Canada’s northernmost freshwater fish species. Specifically, we used a logistic regression model to establish baseline relationships between the current distribution of Arctic charr and the variables, degree-days (a key climate variable), geographical location, and brook charr occurrence. We developed the model applying the expected changes in degree-days to 2050 (25–50% increase from the average of 1976–2005) and 2080 (50–100% increase) while incorporating the historical distribution of Arctic charr to estimate the change in Arctic charr distribution over that time. We found that growing degree-days, longitude, latitude, and brook charr occurrences correctly classified 93% of Arctic charr historical occurrences in Canada. We estimate that in a high-carbon scenario, where degree-days are expected to increase by 50 to 100%, Arctic charr range is projected to decrease by 18% in Canada by 2051–2080 and decrease even further by 3% with the presence of brook charr. The Canadian high Arctic may provide refuge for Arctic charr, likely maintaining temperatures optimal for species persistence. Regardless, management that considers the climate stresses on Arctic charr populations will be important to preserve this highly valued resource that is pivotal for food security and traditional ways of life for northerners.

The Cretaceous to Eocene: a biostratigraphical review and a new detailed palynostratigraphy of Greenland and adjacent areas

The present paper compile and correlate for the first time Cretaceous to Eocene palynostratigraphies across the Arctic. It focus on Greenland and adjacent areas, including the Labrador–Baffin Seaway, onshore Nuussuaq Basin in central West Greenland, onshore southern East Greenland, central East Greenland, North-East Greenland, eastern North Greenland and the Danmarkshavn Basin, but also extends to Canadian Arctic Archipelago and the Barents Sea region off Norway. The paper compile data from more than three decades of detailed Arctic palynological analyses, based mainly on dinoflagellate cysts. The paper gives a historical overview of the Cretaceous to Palaeogene paleontological studies of Greenland and presents an overview of 85 palynological intervals and numerous events. The palynological assemblages from the Labrador–Baffin Seaway, Nuussuaq Basin and north-east Baffin Bay reflect the opening of the Labrador–Baffin Seaway from brackish to freshwater environment in a large embayment in the Early Cretaceous to an open marine seaway in the Late Cretaceous. Assemblages reveal in dinoflagellate cyst provincialism between the opening stages of the Labrador–Baffin Seaway and the already opened Greenland–Norwegian–Barents seaway. The Upper Cretaceous global Oceanic Anoxic Event 2 (OAE2) spanning the Cenomanian/Turonian boundary is recognised from Arctic Canada, north-east Baffin Bay, Nuussuaq Basin in central West Greenland, and North-East Greenland, and is mapped and correlated based on dinoflagellate cyst stratigraphy and carbon isotope (δ13Corg) curves. The dinoflagellate cysts assemblages of the Cretaceous/Palaeogene boundary are correlated from the Labrador Sea across to the Nuussuaq Basin in central West Greenland; in both areas the earliest Danian palynological assemblage is represented by incoming warm-water species. The presence of the global Paleocene–Eocene Thermal Maximum (PETM) in the Palaeogene successions in North-East Greenland and in exploration wells in the Labrador–Baffin Seaway is indicated by the incoming of the warm-water dinoflagellate cyst species Axiodinium augustum.

Estimating Thaw Settlement of Coarse-Grained Permafrost Sediments

Thaw settlement, a frequently reported issue for infrastructure built on permafrost, contributes to high maintenance costs, reduced life cycles, and compromised serviceability of infrastructure. This paper presents a new method to estimate the thaw settlement in coarse-grained permafrost sediments, crucial for northern infrastructure planning. Utilizing available test results from the Canadian Arctic, an overview of the existing data for coarse-grained permafrost sediments is presented. The proposed method uses input parameters derived from particle size distribution to estimate the minimum void ratio of thawed sediments. The minimum void ratio is then used to infer the thawed void ratio, enabling the calculation of thaw strain. The effectiveness of the approach is confirmed by validating predicted thaw strains against measured values for over 60 permafrost samples. A comparison with existing empirical methods shows improved accuracy and reduced bias, further supporting the applicability of the approach. Additionally, an average thawed void ratio assigned to seven groups of granular soils proved valuable for predicting thaw strain when only visual descriptions of sediments are available. Tailored for granular materials and utilizing easily obtainable index properties, this approach provides a reliable and cost-effective method for predicting thaw settlement, benefiting engineers and planners in infrastructure development.

Dietary plasticity and broad North Atlantic origins inferred from bulk and amino acid-specific δ15N and δ13C favour killer whale range expansions into Arctic waters.

Killer whales (Orcinus orca) occur seasonally in the eastern Canadian Arctic (ECA), where their range expansion associated with declining sea ice have raised questions about the impacts of increasing killer whale predation pressure on Arctic-endemic prey. We assessed diet and distribution of ECA killer whales using bulk and compound-specific stable isotope analysis (CSIA) of amino acids (AA) of 54 skin biopsies collected from 2009 to 2020 around Baffin Island, Canada. Bulk ECA killer whale skin δ15N and δ13C values did not overlap with potential Arctic prey after adjustment for trophic discrimination, and instead reflected foraging history in the North Atlantic prior to their arrival in the ECA. Adjusted killer whale stable isotope (SI) values primarily overlapped with several species of North Atlantic baleen whales or tuna. Amino acid (AA)-specific δ15N values indicated the ECA killer whales fed primarily on marine mammals, having similar glutamic acid δ15N-phenylalanine δ15N (δ15NGlx-Phe) and threonine δ15N (δ15NThr) as mammal-eating killer whales from the eastern North Pacific (ENP) that served as a comparative framework. However, one ECA whale grouped with the fish-eating ENP ecotype based δ15NThr. Distinctive essential AA δ13C of ECA killer whale groups, along with bulk SI similarity to killer whales from different regions of the North Atlantic, indicates different populations converge in Arctic waters from a broad source area. Generalist diet and long-distance dispersal capacity favour range expansions, and integration of these insights will be critical for assessing ecological impacts of increasing killer whale predation pressure on Arctic-endemic species.

Modeling of the Impact‐Generated Hydrothermal System at the Haughton Impact Structure

AbstractHypervelocity impacts can generate hydrothermal systems, which have been suggested as candidate environments for prebiotic chemistry on the early Earth. The Haughton impact structure (a 23 km diameter crater located on Devon Island, Nunavut, Arctic Canada) displays evidence of water‐rock alteration indicative of a hydrothermal system generated from a cosmic impact. To model the formation of this crater and subsequent hydrothermal alteration, we have successfully developed a new two‐code methodology that utilizes a shock physics code and a hydrothermal code (HYDROTHERM). We can best reproduce the Haughton crater with a ∼700 m diameter projectile with an impact velocity of 14 km/s. With our approach, we were able to match all the major geological constraints observed at the Haughton impact structure. Our models show that the Haughton crater interior could have sustained temperatures ideal for thermophilic and hyperthermophilic life (50–120°C) for more than 50,000 years, indicating that these systems can sustain prebiotic chemistry and life for longer than previously estimated.

A Comparison of Stephen Harper’s and Justin Trudeau’s Arctic Narratives: Toward a New Geography of the Canadian North

This article intends to compare the political narratives on the Canadian Artic produced by the governments of Conservative Prime Minister Stephen Harper (2006–2015) and Liberal Prime Minister Justin Trudeau (2015–2023), with a specific focus on the identity dimension of these two sets of political narratives. Harper’s Arctic narrative, served by a unique personal commitment of the PM, promoted a radical shift from the historic Canada centred on the Laurentian region to a new Arctic Canada and in so doing, created a new political geography of Canada. In Justin Trudeau’s Arctic narrative, priority was given to reconciliation through the development of state-to-state relations with Indigenous communities. Embodied by the person of Governor General Mary Simon and concretized by the cooperative approach of Trudeau’s Arctic and Northern Framework, this new agentivity of Northern Indigenous peoples has ushered in a new decolonial geography of the Arctic. Unexpectedly, these successive official narratives of Arctic Canada have proven complementary in striving to move the center of gravity of the country north, thus creating new perspectives on Canadian identity and political geography.

Sedimentary biomarkers and bone specimens reveal a history of prehistoric occupation on Somerset Island (Arctic Canada).

Archaeological studies of pre-historic Arctic cultures are often limited to artefacts and architecture; such records may be incomplete and often do not provide a continuous record of past occupation. Here, we used lake sediment archives to supplement archaeological evidence to explore the history of Thule and Dorset populations on Somerset Island, Nunavut (Canada). We examined biomarkers in dated sediment cores from two ponds adjacent to abandoned Thule settlements (PaJs-3 and PaJs-13) and compared these to sediment cores from two ponds without past human occupation. Coprostanol and epicoprostanol, δ15N measurements, sedimentary chlorophyll a and the ratio of diatom valves to chrysophyte cysts were elevated in the dated sediment profiles at both sites during Thule and Dorset occupations. Periods of pronounced human impact during the Thule occupation of the site were corroborated by 14C-dated caribou bones found at both sites that identified intense caribou hunting between ca 1185 and 1510 CE. Notably, these sediment core data show evidence of the Dorset occupation from ca 200 to 500 CE at sites where archaeological evidence was heretofore lacking. We highlight the utility of lake sediments in assisting archaeological studies to better establish the timings, peak occupations and even lifestyle practices of the Dorset and Thule Arctic peoples.

Rift to Post‐Rift Tectonostratigraphy of the Sverdrup Basin in Relation to Onset of the High Arctic Large Igneous Province (HALIP) in the Early Cretaceous, Arctic Canada

AbstractA summary of the Jurassic‐Cretaceous rift to breakup tectonostratigraphy of the onshore Sverdrup Basin is correlated to the offshore Amerasia Basin in order to reconstruct a tectonic setting for the High Arctic Large Igneous Province (HALIP). The rift climax from the Canadian rifted margin is correlated with hyper‐extension of the continent‐ocean‐transition zone. Hyper‐extension of the continental lithosphere can accommodate plate motions of Arctic Alaska‐Chukotka away from the Canadian Arctic Islands and Lomonosov Ridge between ∼155 Ma and 135–133 Ma. After lithospheric breakup at ∼135–133 Ma, correlation of the post‐rift stage to the seafloor spreading anomalies M10n to M4n that are associated with oceanic crustal domains can accommodate plate motions from 135–133 Ma to 128 Ma. The uncertainties associated with the earliest magmas of HALIP overlap with the uncertainties on the timing of the latest seafloor spreading. The first main pulse of HALIP in the Aptian at 124–120 Ma post‐dates seafloor spreading and so HALIP was emplaced in a tectonic setting that closely resembles the present state of the south and eastern Amerasia Basin. At the paleogeographic center of the HALIP, the Alpha Ridge complex is consistent with the magmatic character and history of similar Cretaceous oceanic plateau in terms of volume and duration.

Quantifying Drivers of Seasonal and Interannual Variability of Dissolved Oxygen in the Canada Basin Mixed Layer

AbstractAnalysis of dissolved oxygen (O2) in the Arctic's surface ocean provides insights into gas transfer between the atmosphere‐ice‐ocean system, water mass dynamics, and biogeochemical processes. In the Arctic Ocean's Canada Basin mixed layer, higher O2 concentrations are generally observed under sea ice compared to open water regions. Annual cycles of O2 and O2 saturation, increasing from summer through spring and then sharply declining to late summer, are tightly linked to sea ice cover. The primary fluxes that influence seasonal variability of O2 are modeled and compared to Ice‐Tethered Profiler O2 observations to understand the relative role of each flux in the annual cycle. Findings suggest that sea ice melt/growth dominates seasonal variations in mixed layer O2, with minor contributions from vertical entrainment and atmospheric exchange. While the influence of biological activity on O2 variability cannot be directly assessed, indirect evidence suggests relatively minor contributions, although with significant uncertainty. Past studies show that O2 molecules are expelled from sea ice during brine rejection; sea ice cover can then inhibit air‐sea gas exchange resulting in winter mixed layers that are super‐saturated. Decreasing mixed layer O2 concentrations and saturation levels are observed during winter months between 2007 and 2019 in the Canada Basin. Only a minor portion of the decreasing trend in wintertime O2 can be attributed to decreased solubility. This suggests the O2 decline may be linked to more efficient air‐sea exchange associated with increased open water areas in the winter sea ice pack that are not necessarily detectable via satellite observations.

Patterns of Dietary Energy, Macronutrients, and Fiber Purchased in 21 Canadian Arctic Grocery Stores by Inuit-Defined Season and Community Size Level

Patterns of Dietary Energy, Macronutrients, and Fiber Purchased in 21 Canadian Arctic Grocery Stores by Inuit-Defined Season and Community Size Level

First record of Microbotryum marginale (Microbotryaceae) on Bistorta plumosa

Microbotryum marginale is reported for the first time on Bistorta plumosa, based on a collection from the Yukon coast, Canadian Arctic, at 68°55'N. This locality is a new northern limit for M. marginale in North America.

All Aboard the Nascopie: Image-Making, Colonial Modernity, and Coastal Memory in the Canadian Eastern Arctic

Between 1912 and 1947, when it sank, the icebreaker the RMS Nascopie, a British-made vessel commissioned by the HBC to be used as a supply ship, serviced the eastern Canadian Arctic. For an eight-year period during this time it also counted tourists among its passengers, alongside HBC personnel, missionaries, medical practitioners, scientists, and government officials. Life aboard the ship, wildlife, sea ice, inclement weather, and Inuit were all documented in the reports, written diaries, and visual records that emanated from the Nascopie as it operated under the many, often contradictory, guises of icebreaker, supply vessel, cruise ship, and sovereign symbol. Looking across photography, painting, and printmaking during the 1930s through to the present day, I consider the Nascopie as an anchor between the visual arts and the coastal landscape. Here, I position Inuit and non-Inuit perceptions of cultural and environmental change and continuity along Canada’s coastline within the transformative effect of colonial modernity. Image-making, notably photography and painting, aboard the Nascopie sought to reproduce the Canadian Arctic as an object of collective history and national identity. Confronting the often-anonymous Inuit and Arctic environments throughout the photography and painting of Lorene Squire and F.H. Varley, I identify how the Nascopie, as a colonial actor in the local landscape, persists in contemporary Inuit visual and cultural memory, most notably in the work of Shuvinai Ashoona. By untangling the inter-media and multi-temporal role of the Nascopie across past and present image cultures, I explore the intertwined narratives of coastal history, visual culture, and colonial modernity in the eastern Canadian Arctic.

Detecting Melt Pond Onset on Landfast Arctic Sea Ice Using a Dual C-Band Satellite Approach

The presence of melt ponds on the surface of Arctic Sea ice affects its albedo, thermal properties, and overall melting rate; thus, the detection of melt pond onset is of significant importance for understanding the Arctic’s changing climate. This study investigates the utility of a novel method for detecting the onset of melt ponds on sea ice using a satellite-based, dual-sensor C-band approach, whereby Sentinel-1 provides horizontally polarized (HH) data and Advanced SCATterometer (ASCAT) provides vertically polarized (VV) data. The co-polarized ratio (VV/HH) is used to detect the presence of melt ponds on landfast sea ice in the Canadian Arctic Archipelago in 2017 and 2018. ERA-5 air temperature and wind speed re-analysis datasets are used to establish the VV/HH threshold for pond onset detection, which have been further validated by Landsat-8 reflectance. The co-polarized ratio threshold of three standard deviations from the late winter season (April) mean co-pol ratio values are used for assessing pond onset detection associated with the air temperature and wind speed data, along with visual observations from Sentinel-1 and cloud-free Sentinel-2 imagery. In 2017, the pond onset detection rates were 70.59% for FYI and 92.3% for MYI. Results suggest that this method, because of its dual-platform application, has potential for providing large-area coverage estimation of the timing of sea ice melt pond onset using different earth observation satellites.

Three-dimensional reconstruction of high latitude bamboo coral via X-ray microfocus Computed Tomography

The skeletons of long-lived bamboo coral (Family Keratoisididae) are promising archives for deep-water palaeoceanographic reconstructions as they can record environmental variation at sub-decadal resolution in locations where in-situ measurements lack temporal coverage. Yet, detailed three dimensional (3D) characterisations of bamboo coral skeletal architecture are not routinely available and non-destructive investigations into microscale variations in calcification are rare. Here, we provide high-resolution micro-focus computed tomography (µCT) data of skeletal density for two species of bamboo coral (Acanella arbuscula: 5 specimens, voxel size, 15 µm (central branch scans) and 50 µm (complete structure scan); Keratoisis sp.: 4 specimens, voxel size, 15 µm) collected from the Labrador Sea and Baffin Bay deep-water basins, Eastern Canadian Arctic. These data provide reference models useful for developing methods to assess structural integrity and other fine-scale complexities in many biological, geological, and industrial systems. This will be of wider value to those investigating structural composition, arrangement and/or composition of complex architecture within the fields and subdisciplines of biology, ecology, medicine, environmental geology, and structural engineering.