Dietary plasticity in small Arctic copepods as revealed with prey metabarcoding.

Objectives: Small copepods (<2 mm) compose an important constituent of the Arctic marine food web, but their trophic interactions remain largely unexplored, partly due to methodological limitations. Methods: We here characterize the prey of the abundant cyclopoid Oithona similis, harpacticoid Microsetella norvegica and calanoid Microcalanus spp. from the Arctic Barents Sea and Nansen Basin during four seasons using brute force prey metabarcoding of the 18S rRNA gene. Key findings: Chaetognaths were unexpectedly the most consistently identified taxa and composed 47% of all prey reads. Some taxa were seasonally important, including diatoms in April-May (43%), dinoflagellates in December (15%) and March (17%), and urochordates in August (20%). Compositional differences among species were also discernible, and the M. norvegica diet was significantly different from both O. similis and Microcalanus spp. The diets varied nevertheless more with season than species despite the inherent trophic traits that distinguish the ambush-predator O. similis, chemosensoric particle-chaser M. norvegica and current-feeding Microcalanus spp. Conclusions: Our results thus indicate that dietary plasticity is common in small Arctic copepods, regardless of their behaviors or strategies for finding sustenance. We further hypothesize that such plasticity is an important adaptation in systems where prey availability is highly seasonal.

Summer primary production of Arctic kelp communities is more affected by duration than magnitude of simulated marine heatwaves.

Fjord systems in the Norwegian Arctic are experiencing an increasing frequency and magnitude of marine heatwaves. These episodic heat stress events can have varying degrees of acute impacts on primary production and nutrient uptake of mixed kelp communities, as well as modifying the biogeochemical cycling in nearshore systems where vast areas of kelp create structural habitat. To assess the impact of future marine heatwaves on kelp communities, we conducted a 23 day mesocosm experiment exposing mixed kelp communities to warming and heatwave scenarios projected for the year 2100. Three treatments were considered: a constant warming (+1.8°C from the control), a medium magnitude and long duration heatwave event (+2.8°C from the control for 13 days), and two short-term, more intense, heatwaves(5 day long scenarios with temperature peaks at +3.9°C from the control). The results show that both marine heatwave treatments reduced net community production, whereas the constant warm temperature treatment displayed no difference from the control. The long marine heatwave scenario resulted in reduced accumulated net community production, indicating that prolonged exposure had a greater severity than two high magnitude, short-term heatwave events. We estimated an 11°C temperature threshold at which negative effects to primary production appeared present. We highlight that marine heatwaves can induce sublethal effects on kelp communities by depressing net community production. These results are placed in the context of potential physiological resilience of kelp communities and implications of reduced net community production to future Arctic fjord environmental conditions.

Assessing the impact of Arctic shipping routes on the global container shipping network's connectivity.

Amidst the intensifying impact of climate change, the extension of navigable periods along Arctic Shipping Routes (ASRs) has garnered attention as a maritime route for container vessels. The urgency to comprehend the reverberations of ASRs on the global container shipping network (GCSN) led to the development of the Latitudinal Centrality Index (LCI), which integrates latitude and centrality in maritime analysis. This index evaluates ASRs' influence across 968 port nodes within the GCSN. By exploring scenarios encompassing seasonal fluctuations over the years, this study delves into the sway of ASRs compared to a benchmark state devoid of ASR engagement. The study's revelations highlight a discovery: the assimilation of ASRs augments interconnectivity, or resilience, within the GCSN. The GCSN thrives as a cohesive and adaptable entity upon full integration of ASRs, indicating a promising trajectory for global container shipping.

Machine learning-based modeling of surface water temperature dynamics in arctic lakes.

Lake surface-water temperature (LSWT) regulates physical and biochemical processes in lakes. Therefore, understanding the LSWT dynamics is important, especially in Arctic zone since the region is experiencing a warming rate that is greater than the Earth's average. However, regular measurements of LSWT in the remote Arctic lakes always face difficulties or cannot be done by satellites accurately due to the cloud cover and their limited spatiotemporal resolution. Here, we used a historically rich data (1960-2023) to develop four machine learning-based algorithms for the daily LSWT modeling in Lake Inari, situated in Arctic zone, using the air-temperature data. Our results showed that both air-temperature (0.030 °C/yr) and LSWT (0.023m °C/yr) were warming with a rate faster than those in the globe. The long-short-term memory model, with the coefficients of determination varied from 0.96 to 0.98, outperformed other algorithms in modeling of the daily LSWT dynamics in Lake Inari, followed by both support vector regression and neural network tools, and random forest model. As the air-temperature data are widely accessible through synoptic stations and remote sensing techniques, our suggested models can be simply adopted for other Arctic lakes, where the local water-temperature data are often lacking or contain large windows of missing data due to harsh atmospheric conditions and equipment failure.

Warming reduces trophic diversity in high-latitude food webs.

The physical effects of climate warming have been well documented, but the biological responses are far less well known, especially at the ecosystem level and at large (intercontinental) scales. Global warming over the next century is generally predicted to reduce food web complexity, but this is rarely tested empirically due to the dearth of studies isolating the effects of temperature on complex natural food webs. To overcome this obstacle, we used 'natural experiments' across 14 streams in Iceland and Russia, with natural warming of up to 20°C above the coldest stream in each high-latitude region, where anthropogenic warming is predicted to be especially rapid. Using biomass-weighted stable isotope data, we found that community isotopic divergence (a universal, taxon-free measure of trophic diversity) was consistently lower in warmer streams. We also found a clear shift towards greater assimilation of autochthonous carbon, which was driven by increasing dominance of herbivores but without a concomitant increase in algal stocks. Overall, our results support the prediction that higher temperatures will simplify high-latitude freshwater ecosystems and provide the first mechanistic glimpses of how warming alters energy transfer through food webs at intercontinental scales.

3D built virtual arctic environment increase vigor through connectedness in older people.

While the life expectancy of older people has increased significantly, this is often related to more long-term care in healthcare residences and nursing homes. Staying in these facilities can lead to a reduction in the sense of connection with others and the world around, as well as in vigor, with significant psychophysical repercussions in the long term. Although previous studies have shown that the virtual nature can benefit both, there are no significant studies that have tested its effect in generating these positive outcomes in the older population. Therefore, our study sought to investigate, in a sample of 53 older people in care at a nursing home or healthcare residence, the indirect effect of a 3D built virtual arctic environment (vs. a 3D built virtual urban environment) exposure in virtual reality on vigor through connectedness. Both the virtual scenarios were designed with a first-person view, with no translation around the environment and only in-situ rotation. Results highlighted that exposure to the 3D built virtual arctic environment leads to higher connectedness than the 3D built virtual urban environment, and this, in turn, leads to an increase in vigor. Findings were discussed based on the potential of adopting virtual nature in facilities to improve older people's sense of connectedness and, in turn, improve their well-being.

Interaction between three key species in the sea ice-reduced Arctic Barents Sea system.

Population dynamics depend on trophic interactions that are affected by climate change. The rise in sea temperature is associated with the disappearance of sea ice in the Arctic. In the Arctic part of the Barents Sea, Atlantic cod, capelin and polar cod are three fish populations that interact and are confronted with climate-induced sea ice reductions. The first is a major predator in the system, while the last two are key species in Arctic and sub-Arctic ecosystems, respectively. There are still many unknowns regarding how predicted environmental change may influence the joint dynamics of these populations. Using time series from a 32 year long survey, we developed a state-space model that jointly modelled the dynamics of cod, capelin and polar cod. Using a hindcast scenario approach, we projected the effect of reduced sea ice on these populations. We show that the impact of sea ice reduction and concomitant sea temperature increase may lead to a decrease of polar cod abundance at the benefit of capelin but not of cod which may decrease, resulting in strong changes in the food web. Our analyses show that climate change in the Arcto-boreal system can generate different species assemblages and new trophic interactions, which is the knowledge needed for effective management measures.

Key recommendations and research priorities of the 2021 AMAP human health assessment.

Over the last three decades, the Arctic Monitoring and Assessment Programme has published five human health assessments. These assessments have summarised the current state of the science regarding environmental contaminants and human health in the Arctic. The 2021 Human Health Assessment Report had a particular focus on dietary transitions, in addition to human biomonitoring levels and trends, health effects, risk assessment methodologies, risk communication and multi-disciplinary approaches to contaminants research. The recommendations and research priorities identified in the latest assessment are summarised here to assist decision- and policy-makers in understanding and addressing the impacts of contaminants on human populations in the Arctic.

Seasonal dynamics of chemistry in an Arctic glacier-fed river.

Arctic rivers, intricately linked to fjord systems, wield significant influence over the geochemical and biological dynamics of the upper Arctic Ocean, providing it with freshwater, nutrients, suspended particles, and potentially harmful pollutants. To comprehend the full picture of the Arctic ecosystem, it is crucial to understand how these rivers vary across regions and seasons, especially considering ongoing climate changes. However, comprehensive studies that address long-term observations and seasonal variations in Arctic rivers' geochemical composition remain scarce. In this study, we present comprehensive long-term investigations of the seasonal variations in elemental concentrations in Bayelva, a high Arctic glacier-fed river. By analyzing 224 surface water samples, collected during different seasons between 2011 and 2020, we elucidate the diverse influences of marine, geological and atmospheric factors on the river chemistry. Our findings underscore the importance of marine-influenced snowmelt in the early flow season, which leads to elevated concentrations of marine and trace elements in the runoff water at the onset of melting, with concentrations subsequently decreasing as the snow melting continues. Glacial meltwater dominates the river chemistry during the peak flow season, during which elemental concentrations are at their lowest. Late flow season exhibits high elemental concentrations, primarily driven by weathering processes. Additionally, heavy rain and freezing events play a crucial role in sudden alterations in river chemistry. We highlight the dynamic response of Arctic river systems to such environmental drivers as key players in transporting essential micro- and macro-nutrients, as well as potentially harmful pollutants to adjacent fjord systems. Given their susceptibility to climate change, continuous monitoring is essential for understanding future changes. This study provides data for a better foundation for accurate climate modeling of biogeochemical systems in the Arctic environment.

Skin diseases among adults in Tasiilaq, East Greenland.

Cold climate and unique genetic and environmental factors may influence the prevalence of skin diseases in Greenland. However, there is a lack of epidemiological studies on skin diseases in the adult Greenlandic population. To address this unmet need a cross-sectional study, run by dermatologists from Denmark, the UK, and Switzerland estimated the prevalence and clinical manifestations of skin diseases among adults in East Greenland in May 2022. All adults ≥18 years in the town of Tasiilaq were invited, and 295 individuals aged 18-78 years participated (22.5% of the overall adult population in Tasiilaq). Two-hundred and three participants (69%) had visible signs of current skin disease, and among these, 242 cases of dermatoses were identified. The most common skin diseases were hand eczema (22.4%), lichen simplex (9.5%), discoid eczema (7.1%), psoriasis, atopic dermatitis and acne vulgaris (5.8% each). Scabies was the most frequent infectious skin disease (4.4%). No cases of skin cancer were identified. Atopic dermatitis and psoriasis presented with disease that was of limited extent and different from the classical presentations. Skin diseases showed a high prevalence among adults in East Greenland, and some of them were severe. This indicates a noteworthy public health problem that warrants better access to dermatologist support.

The potential of oviduct tags and fine-scale acoustic telemetry to reveal the timing and location of spawning in Arctic salmonids (Salvelinus spp.).

Identifying and characterizing spawning locations are paramount for the protection of critical fish habitats but can be challenging, particularly in remote locations. Using the underexplored oviduct-tagging technique, we aimed to identify the timing and location of spawning for wild Arctic char (Salvelinus alpinus) and lake trout (Salvelinus namaycush) in two high-Arctic lakes in Nunavut. Specifically, Innovasea V7 acoustic telemetry transmitters were inserted into the oviducts of 13 Arctic char and 4 lake trout, and the timing and location of tag expulsion were determined using a fine-scale positioning system. Twenty Arctic char and 20 lake trout were also tagged with abdominal V16 transmitters, and 10 of them were paired with the oviduct tags, to further study the behavior of individual fish during the spawning season. Oviduct tags from four Arctic char and one lake trout could be used to assess the timing and location of spawning. Spawning anadromous Arctic char drastically reduced their activity and remained proximate to their presumed spawning location immediately before and for months after spawning. In contrast, a non-anadromous (i.e., freshwater resident) Arctic char and a lake trout showed little to no reduction in activity around presumed spawning events. Because of the highlighted sedentary behavior of inferred spawning anadromous Arctic char implanted with both abdominal and oviduct tags, we could also infer potential spawning based on the behavior of individuals equipped only with abdominal tags. Spawning areas identified via telemetry also aligned well with Inuit knowledge of those lakes. This is the first field study to use acoustic oviduct and abdominal tags coupled with a fine-scale positioning system. Despite a limited success rate of ejection, the study reveals the strong potential of the method to study spawning habitat and timing, particularly in remote areas.

High temperature and hyperkalemia increase vulnerability of navaga cod (Eleginus nawaga) cardiomyocytes to the ecotoxicant 3-methyl-phenanthrene.

Oil and gas mining and transportation in the Arctic can lead to release of polycyclic aromatic hydrocarbons (PAHs) in the ocean and freshwater basins. PAHs are known for their toxic effects in fish hearts, including the inhibition of main ionic currents (IKr, INa and ICaL) in fish cardiac myocytes. The present study is the first one to assess the effect of a particular PAH abundant in crude oil and diesel, namely 3-methyl-phenanthrene (3-MP), on the electrical excitability (EE) of cardiomyocytes from navaga cod (Eleginus nawaga), commercial fish species from the Arctic. Action potentials (APs) were elicited in current-clamp experiments at 9, 15 and 21 °C, and AP characteristics and the current needed to elicit APs were examined. Also, the effects of 3 µM 3-MP were tested at 3 temperatures and in normal (3.5 mM) and high (8 mM) extracellular K+ concentrations. Elevation of temperature leads to hyperpolarization of resting membrane potential and AP shortening, but does not decrease EE. 3-MP was found to suppress EE in cardiomyocytes at 9 and 15 °C, but not at 21 °C. High extracellular K+ itself drastically decreases EE, although it does not worsen the effect of 3-MP. However, combination of hyperthermia and high K+ leads to augmentation of depressive effect of 3-MP on EE. We hypothesize that hyperthermia rescues Na+ channels from inactivation due to membrane hyperpolarization, thereby compensating for the partial inhibition of INa by 3-MP. However, elevation of extracellular K+ nullifies this protective mechanism by depolarizing the resting potential and aggravates the effect of 3-MP.

Scaling the high latitudes: evolution, diversification, and dispersal of Coryphella nudibranchs across the Northern Hemisphere.

Nudibranch molluscs Coryphella are widely distributed and species-rich gastropod group lacking fossil record and displaying a complex distribution across both Southern and Northern hemispheres. In this paper we provide a detailed review of the morphology, ecology, and distribution of Coryphella, estimation of divergence times between species, an ancestral area reconstruction, and a population analysis of widely distributed trans-Arctic species Coryphella verrucosa to investigate the evolution, phylogeographic patterns and reconstruct possible historical routes of oceanic dispersal. The inclusion of a larger sample size and five molecular markers has revealed a complex evolutionary history of Coryphella, shaped by transgression, vicariance, and dietary shifts, and overall driven by the pervasive effect of glacial cycles. We also revealed the presence of additional cryptic diversity, which suggests that further sampling may produce additional species in this group of nudibranchs. Tree calibration indicates the genus Coryphella originates in the middle Miocene in the Pacific Ocean and the early divergence within this group also occurred in the Pacific, specifically in different regions of the North Pacific. The ancestral area reconstruction inferred five independent instances of transgression from the Pacific Ocean to the Atlantic via different migration routes, including the Panamanian seaway and the Bering Strait. Among them, we identified three cases of successful transition to the Arctic waters from the North Pacific via the Bering Strait, associated with interglacial conditions of middle Pleistocene. Consequently, Pleistocene glacial cycles likely prompted pulses of boreal faunal elements to disperse southwards followed by range disjunction and temporary isolation of distant populations and resulting in allopatric speciation. Evidence from the population structure of contemporary trans-Arctic species suggests an occurrence of independent recolonization pathways of Arctic waters from both southernly and northernly refugia after the Last Glacial Maximum.

Regulation of Ocean Surface Currents and Seasonal Sea Ice Variations on the Occurrence and Transport of Organophosphate Esters in the Central Arctic Ocean.

Organophosphate esters (OPEs) have been observed in the remote Arctic Ocean, yet the influence of hydrodynamics and seasonal sea ice variations on the occurrence and transport of waterborne OPEs remains unclear. This study comprehensively examines OPEs in surface seawater of the central Arctic Ocean during the summer of 2020, integrating surface ocean current and sea ice concentration data. The results confirm significant spatiotemporal variations of the OPEs, with the total concentration of seven major OPEs averaging 780 ± 970 pg/L. Chlorinated OPEs, particularly tris(1-chloro-2-propyl) phosphate (TCPP), were dominant. The significant impact of hydrodynamics on the OPE transport is demonstrated by higher OPE concentrations in regions with strong surface currents, especially at the edge of the Beaufort Gyre and the confluence of the Beaufort Gyre and the Transpolar Drift. Furthermore, OPE levels were generally higher in drifting-ice-covered regions compared to ice-free regions, attributed to the volatilization of dissolved OPEs formerly trapped below the sea ice or newly released from melting snow and sea ice. Notably, TCPP decreased by only 19% in the ice-free area, while the more volatile triphenyl phosphate decreased by 63% compared with the partial ice region.

Pesticides under the category of persistent organic pollutants and emerging contaminants in surface sediments of an Arctic Fjord and nearby lakes.

This study focuses on the distribution of some selected organochlorine pesticides and emerging contaminants within the surface sediments of an Arctic fjord, Kongsfjorden and nearby lakes. Organochlorine pesticides (OCPs) such as dicloran, p,p'-DDT, p,p'-DDE, p,p'-DDD were studied along with five emerging contaminants namely diuron, chlorpyrifos, dicofol, pendimethalin and bifenthrin. The highest values of OCPs recorded among the fjord and lake environments during the time of study was 0.3355 ng/g (dicloran), 0.0152 ng/g (p,p'-DDT), 0.0117 ng/g (p,p'-DDE), and 0.0137 ng/g (p,p'-DDD). Except dicofol, all other pesticides were found in both the years (2018 & 2019) with an elevated concentration during 2019. The presence of fresh as well as past input of contaminants was obtained from the values of DDTs ratio. The sediment quality guidelines of DDTs confirm that the fjord and lakes are clean to marginally polluted in which the adverse effects can rarely occur at this present juncture.

Evaluation of the potentially toxic elements and radionuclides in the soil sample of Novaya Zemlya in the Arctic Circle.

The study presented here elucidate the concentrations of radionuclides and potentially toxic elements in the soil samples around the Novaya Zemlya in the Russian Arctic zone, determined using HPGe gamma spectrometry, inductively coupled plasma optical emission spectrometry and direct mercury analyzer. The average detected concentrations for 226Ra, 232Th, 40K, 235U and 137Cs were 36.40, 46.06, 768, 2.06 and 4.71 Bq/kg, respectively. At many sampling sites, the concentrations of potentially toxic elements (Zn, Cu, Pb, Cd, Ni, and Cr) were higher than the natural levels. Positive Matrix Factorization analysis revealed the contribution of oil dumps (32%), natural sources (16%), bird colonies (32%) and atmospheric deposition (20%) for elevated elements content. In the case of radionuclides, the natural occurring contamination (38%) was primary source followed by dumped material (32%) and bird colonies (30%). The radiological risk from radionuclides was relatively high, yet still under permissible levels. For potentially toxic elements, Fe was predominant non-carcinogenic pollutant and Ni emerged as major carcinogenic contaminant. Keeping in view the high content of some elements, future studies are required to keep the human and ecological risk low, and to establish scientific grounds for the contribution of settled bird species. The findings of the study advance the present knowledge about the contamination of the study area and lays the path for further effort.

A chromosome-level genome assembly of the common eider, Somateria mollissima (Linnaeus, 1758).

The common eider, Somateria mollissima mollissima (Chordata; Aves; Anseriformes; Anatidae), is a large sea duck with a circumpolar distribution. We here describe a chromosome-level genome assembly from an individual female. The haplotype-resolved assembly contains one pseudo-haplotype spanning 1205 megabases (with both Z and W sex chromosomes) and one pseudo-haplotype spanning 1080 megabases. Most of these two assemblies (91.13% and 93.18%, respectively) are scaffolded into 32 autosomal chromosomal pseudomolecules plus Z and W for pseudo-haplotype one. The BUSCO completeness scores are 94.0% and 89.9%, respectively, and gene annotations of the assemblies identified 17,479 and 16,315 protein coding genes. Annotation of repetitive sequences classify 17.84 % and 14.62 % of pseudo-haplotype one and two, respectively, as repeats. The genome of the common eider will be a useful resource for the widely distributed northern species in light of climate change and anthropogenic threats.

Chemolithoautotrophic bacteria flourish at dark water-ice interfaces of an emerged Arctic cold seep.

Below their ice shells, icy moons may offer a source of chemical energy that could support microbial life in the absence of light. In the Arctic, past and present glacial retreat leads to isostatic uplift of sediments through which cold and methane-saturated groundwater travels. This fluid reaches the surface and freezes as hill-shaped icings during winter, producing dark ice-water interfaces above water ponds containing chemical energy sources. In one such system characterized by elevated methane concentrations - the Lagoon Pingo in Adventdalen, Svalbard (~10 mg/L CH4, <0.3 mg/L O2, -0.25°C, pH 7.9), we studied amplicons of the bacterial and archaeal (microbial) 16S rRNA gene and transcripts in the water pond and overlaying ice. We show that active chemolithoautotrophic sulfur-oxidizing microorganisms (Sulfurimonas, Thiomicrorhabdus) dominated a niche at the bottom of the ice in contact with the anoxic water reservoir. There, the growing ice offers surfaces interfacing with water, and hosts favorable physico-chemical conditions for sulfide oxidation. Detection of anaerobic methanotrophs further suggests that the ice led to a steady-state dark and cold methane sink under the ice throughout winter, in two steps: first methane is oxidized to carbon dioxide and sulfates concomitantly reduced to sulfides by the activity of ANME-1a and SEEP-SRB1 consortia, in a second time energy from sulfides is used by sulfur- oxidizing microorganisms to fix carbon dioxide into organic carbon. Our results underline ice- covered and dark ecosystems as a hitherto overlooked oasis of microbial life and emphasize the need to study microbial communities in icy habitats.

Toxoplasma gondii DNA in Tissues of Anadromous Arctic Charr, Salvelinus alpinus, Collected From Nunavik, Québec, Canada.

BACKGROUND: Toxoplasma gondii is a very common zoonotic parasite in humans and animals worldwide. Human seroprevalence is high in some regions of Canada's North and is thought to be associated with the consumption of traditionally prepared country foods, such as caribou, walrus, ringed seal and beluga. While numerous studies have reported on the prevalence of T. gondii in these animals, in the general absence of felid definitive hosts in the North there has been considerable debate regarding the source of infection, particularly in marine mammals. It has been proposed that fish could be involved in this transmission. AIMS: The objectives of the present study were to perform a targeted survey to determine the prevalence of T. gondii DNA in various tissues of anadromous Arctic charr sampled in Nunavik, Québec, and to investigate the possible role of this commonly consumed fish in the transmission of infection to humans and marine mammals in Canada's North. METHODS AND RESULTS: A total of 126 individual Arctic charr were sampled from several sites in Nunavik, and various tissues were tested for the presence of T. gondii DNA using PCR. Overall, 12 out of 126 (9.5%) Arctic charr tested in the present study were PCR-positive, as confirmed by DNA sequencing. Brain tissue was most commonly found to be positive, followed by heart tissue, while none of the dorsal muscle samples tested were positive. CONCLUSIONS: Although the presence of T. gondii DNA in brain and heart tissues of Arctic charr is very intriguing, infection in these fish, and their possible role in the transmission of this parasite to humans and marine mammals, will need to be confirmed using mouse bioassays. Arctic charr are likely exposed to T. gondii through the ingestion of oocysts transported by surface water and ocean currents from more southerly regions where the definitive felid hosts are more abundant. If infection in Arctic charr can be confirmed, it is possible that these fish could play an important role in the transmission of toxoplasmosis to Inuit, either directly through the consumption of raw fish or indirectly through the infection of fish-eating marine mammals harvested as country foods.

Use of a Glaciogene Marine Clay (Ilulissat, Greenland) in a Pilot Production of Red Bricks.

Uplifted occurrences of fine-grained glaciogene marine sediments are found throughout the northern hemisphere. These sediments could be used to produce local construction materials, to rely less on imported construction materials from southern regions. In this study, a representative occurrence from Ilulissat, West Greenland, was investigated as a potential resource for local brick production. The study comprised three parts: (1) raw material characterization based on grain size distribution, major element chemistry, including total carbon, sulfur, and chloride concentrations, mineralogy, morphology, and Atterberg limits; (2) the production of test bricks at a Danish brickwork; and (3) testing of the bricks based on total shrinkage, water absorption, hygroscopic adsorption, open porosity, bulk density, compression strength, and mineralogy. The bricks produced proved to have excellent compression strength, low open porosity, and low water absorption. The shrinkage could be reduced by adding 10% chamotte to the marine sediment. Based on the investigated properties, this indicates that this type of clay is highly suitable as a resource for bricks.