Clyde River Research Articles

Sailors, Spies, and Sovereignty: Greenock’s Revolutionary Turmoil, 1688–1691

Despite many pamphlets and news sources declaring the Jacobites defeat in 1690, the Williamite War in Ireland carried on until June 1691. Among the more cautious observers of the situation was the Scottish Privy Council. Records indicate that coastal towns – in this case Greenock – were potential avenues for Jacobite invasion from the Irish Sea. This article situates the Privy Council’s and local action in both their environmental contexts and within the history of borders and borderlands. It traces Greenock’s place in the revolutionary narrative as a place of great strategic importance because of the bustling port and proximity to the city of Glasgow. Coastal and port security played a crucial role in shaping attitudes and action towards the western port towns connected to the Irish Sea. Ultimately, the Clyde River did not succumb to the enemy navy, but the coast and its inland waterways were an unpredictable space.

On the Creation, Depletion, and End of Life of Polar Cap Patches

AbstractIonospheric convection patterns from the Super Dual Auroral Radar Network are used to determine the trajectories, transit times, and decay rates of three polar cap patches from their creation in the dayside polar cap ionosphere to their end of life on the nightside. The first two polar cap patches were created within 12 min of each other and traveled through the dayside convection throat, before entering the nightside auroral oval after 104 and 92 min, respectively. When the patches approached the nightside auroral oval, an intensification in the poleward auroral boundary occurred close to their exit point, followed by a decrease in the transit velocity. The last patch (patch 3) decayed completely within the polar cap and had a lifetime of only 78 min. After a change in drift direction, patch 3 had a radar backscatter power half‐life of 4.23 min, which reduced to 1.80 min after a stagnation, indicating a variable decay rate. 28 minutes after the change in direction, and 16 min after coming to a halt within the Clyde River radar field‐of‐view, patch 3 appeared to reach its end of life. We relate this rapid decay to increased frictional heating, which speeds up the recombination rate. Therefore, we suggest that the slowed patch motion within the polar cap convection pattern is a major factor in determining whether the patch survives as a recognizable density enhancement by the time the flux tubes comprising the initial patch cross into the nightside auroral oval.

Extreme Arctic Weather and Community Impacts in Nunavut: A Case Study of One Winter’s Storms and Lessons for Local Climate Change Preparedness

Abstract Arctic communities are experienced with severe weather, but impacts can still be serious, particularly when the intensity or persistence of hazardous conditions is extreme. Such was the case for the community of Clyde River (Kangiqtugaapik), Nunavut, Canada, which experienced 33 blizzard days during winter 2021/22—likely the most at Clyde River since at least 1978/79. Blizzard conditions resulted from unusually frequent high winds rather than excessive snowfall. The most severe stretch included eight blizzard days over an 11-day period, with top wind gusts of 98 km h−1. Winds caused severe drifting, covering homes and blocking streets. Broken heavy equipment, including snow-clearing machines, compounded the impacts, leaving homes without essential services like water delivery and sewage pump-out for days. Residents reported the storms and resulting impacts as some of the worst in memory. The drifting and volume of snow, combined with the lack of available resources to manage it, obliged the community to declare a state of emergency. Projections of increased Arctic precipitation and extreme weather events points to the need for communities to have proper resources and supports, including preparedness and adaptation and mitigation strategies, so they can be better equipped to handle storm and blizzard impacts such as those experienced at Clyde River in the winter of 2021/22. Additional steps that can be implemented to better support and prepare communities include investing in preparedness planning, expanded and enhanced weather information and services, community land-based programming to transfer Inuit knowledge and skills, assessing the usefulness of current forecasts, and new approaches to community planning. Significance Statement In this study, we consider the winter of 2021/22, during which the community of Clyde River (Kangiqtugaapik), Nunavut experienced 33 days with blizzard conditions—more than any other year since at least 1978/79. Blizzards are characterized by strong winds and blowing snow. Low visibility impedes travel, and drifting snow blocks roads and can bury equipment and buildings. In this case, broken snow-clearing equipment and other infrastructure challenges also hampered the community’s ability to respond, and residents went days without essential services. Several studies suggest that extreme winds will become more common in the Baffin Bay region in the future. This study demonstrates the need for proper resourcing of communities for preparedness, response, and adaptation strategies, especially with the possibility of extreme winter weather becoming more common.

The organic geochemistry of Permian high latitude sediments in two boreholes in the southern Sydney Basin, New South Wales, Australia

Twenty six samples of Permian high latitude sedimentary rocks from the southern Sydney Basin were analysed using organic geochemical methods for their thermal maturity, organic matter inputs, and depositional environment. Fourteen samples are from the Elecom Clyde River (ECR) DDH01 borehole (inland; Southern Highlands), and 12 are from the ECR-DDH07 borehole (coastal; near Nowra). The analysed formations are the Berry Siltstone, the Nowra Sandstone, the Wandrawandian Siltstone, the Snapper Point Formation and the Pebbley Beach Formation. This study is the first organic geochemical study of samples from the Berry Siltstone and Nowra Sandstone. The formations mostly have total organic carbon varying from 1 to 2 wt%, but the Snapper Point Formation is leaner in TOC (0.2–0.7 wt%). The samples vary from low to very high thermal maturity. The samples from the ECR-DDH01 borehole are in the early to middle of the oil window (vitrinite reflectance equivalent = 0.60–0.80%), based on hopane, sterane, alkylnaphthalene, alkylphenanthrene, alkylbiphenyl, and alkyldibenzothiophene thermal maturity parameters. The samples from the ECR-DDH07 borehole are much more thermally mature, in the late part of the oil window to the early gas window (vitrinite reflectance equivalent = 1.2–1.7%). This high thermal maturity has led to the loss of nearly all polycyclic biomarkers, and the thermal rearrangement of many groups of compounds, including monomethylalkanes. The ECR-DDH01 borehole location and time-equivalent outcrop samples south-west of Ulladulla have similar thermal maturities and are close to the margins of the Sydney Basin, and it is estimated to have previously been covered by about 3 km of overburden. In contrast, the samples in the ECR-DDH07 borehole were buried much deeper, with about 4–5 km of overburden, which means that only limited information about their source inputs and depositional environment could be recovered. Aliphatic biomarker, n-alkane and aromatic data are consistent with an overall strong terrigenous organic matter input for the samples from the ECR-DDH01 borehole. Sterane/hopane ratios are mostly low, but only a few compounds diagnostic of specific source inputs were identified. There is a microbially-dominated sample near the base of the Snapper Point Formation (high C29 αβ hopane/C30 αβ hopane ratio and 2α-methylhopanes), and high amounts of parent polycyclic aromatic hydrocarbons in some samples from the Berry Siltstone, likely reflecting an occasional pyrogenic signature from palaeo-forest fires. Several parameters, including sterane carbon number distributions, terpane ratios and the relative abundance of dibenzofuran compared to phenanthrene show that the samples from the ECR-DDH01 borehole have a more strongly terrigenous signal than the previously analysed outcrop samples. This is inferred to be because the ECR-DDH01 location was closer to the palaeo-shoreline than the likely more distal outcrop samples. Based on the pristane/phytane ratio and hopane distributions, deposition of the sediments was under varying oxicity conditions, from highly oxic to suboxic. The inferred environments are marine shale/lacustrine and fluvial/deltaic, so the organic geochemical data agrees with the Permian depositional history of the southmost part of the Sydney Basin previously inferred from sedimentological and palaeogeographic studies.

Quantifying excess heavy metal concentrations in drainage basins using conservative mixing models

High concentrations of heavy metals and other pollutants in river sediments can have detrimental effects on the ecosystem and humans. The composition of river sediments throughout drainage basins therefore provides important information for environmental monitoring. An obvious first step for using river sediment compositions for monitoring is to quantify natural baseline concentrations. Once baselines have been quantified, it is straightforward to compare them to observations to identify excesses generated by, for example, anthropogenic inputs. In this study a new strategy for mapping element concentrations along rivers from discrete geochemical observations upstream is presented. We demonstrate our approach in a case study of the Clyde drainage basin in western Scotland, UK. First, continuous baselines are generated using simple forward models that conservatively mix source region concentrations along drainage networks. 1185 measurements of elemental concentrations from first-order streams are used to parameterise the source region. The calculated baselines are then compared to concentrations measured at 60 localities along the main channel of the Clyde river. For a range of major and trace elements (e.g., Mg, Sr, K, Mn), the downstream observations are in close agreement with baseline concentrations predicted by conservative mixing models. However, some heavy metal concentrations (Pb, Cu, Zn) tend to exceed predicted baseline concentrations. Therefore, the second part of our approach calculates element concentrations in source areas required to match the observed Pb, Cu and Zn concentrations measured along the river. An inverse approach is used to ‘unmix’ the observed concentrations utilising, again, a conservative mixing model. Model resolution is determined by the spatial distribution of the data. Resultant calculated natural baselines and heavy metal concentrations along the river can easily be compared to estimate excesses. We tentatively suggest that anthropogenic input to sediment composition along the river is equivalent to annual fluxes of 9.7, 1.5 and 5.7 t (106 g) of Pb, Cu and Zn, respectively.

Redescription of Euastacus clydensis Riek, 1969 (Crustacea: Parastacidae), a valid species of spiny crayfish from southern New South Wales, Australia

The Giant Sydney Crayfish (Euastacus spinifer (Heller, 1865)) was thought to have a wide range in New South Wales, Australia, spanning some 600 km north-south. A recent extensive molecular phylogenetic and population genomic analysis of E. spinifer across its geographical range revealed strong population structure corresponding to several major geographically correlated clades, the southernmost clade being the most genetically divergent and clearly a separate species. This southern clade corresponds to the junior synonym E. clydensis Riek, 1969 and is sister to the clade comprising the remaining populations of E. spinifer and Euastacus vesper. We formally remove E. clydensis from the synonymy of E. spinifer, increasing the recognised number of species of Euastacus to 54. Euastacus clydensis is redescribed based on type and other material, and is distinguished from E. spinifer by differences in abdominal spination and the form of the antennal scaphocerite. Euastacus clydensis has a restricted southern New South Wales range in the Shoalhaven and Jervis Bay-Clyde River catchments, from Moss Vale south to the vicinity of Clyde Mountain; much of the known range of E. clydensis was burnt in the 2019-2020 eastern Australian megafires.

Characteristics of extreme daily precipitation events over the Canadian Arctic

AbstractGiven growing interest in extreme high‐latitude weather events, we use records from nine meteorological stations and atmospheric reanalysis data to examine extreme daily precipitation events (leading, 99th and 95th percentile) over Arctic Canada. Leading events span 90 mm at Cape Dyer, along the southeast coast of Baffin Island, to 26 mm at Sachs Harbour, on the southwest coast of Banks Island. The 95th percentiles range from 20 to 30% of leading event sizes. Extreme events are most common on or near the month of climatological peak precipitation. Contrasting with Eurasian continental sites having a July precipitation peak corresponding to the seasonal peak in precipitable water, seasonal cycles in precipitation and the frequency of extremes over Arctic Canada are more varied, reflecting marine influences. At Cape Dyer and Clyde River, mean precipitation and the frequency of extremes peak in October when the atmosphere is quickly cooling, promoting strong evaporation from Baffin Bay. At all stations, leading events involved snowfall and strong winds and were associated with cyclone passages (mostly of relatively strong storms). They also involved strong vapour fluxes, sometimes associated with atmospheric rivers or their remnants. The most unusual sequence of events identified here occurred at Clyde River, where the three largest recorded precipitation events occurred in April of 1977. Obtaining first‐hand accounts of this series of events has proven elusive. Identified links between extreme events and atmospheric rivers demonstrates the need to better understand how the characteristics of such features will change in the future.

Real-Time Environmental Monitoring for Aquaculture Using a LoRaWAN-Based IoT Sensor Network.

IoT-enabled devices are making it easier and cheaper than ever to capture in situ environmental data and deliver these data—in the form of graphical visualisations—to farmers in a matter of seconds. In this work we describe an aquaculture focused environmental monitoring network consisting of LoRaWAN-enabled atmospheric and marine sensors attached to buoys on Clyde River, located on the South Coast of New South Wales, Australia. This sensor network provides oyster farmers operating on the river with the capacity to make informed, accurate and rapid decisions that enhance their ability to respond to adverse environmental events—typically flooding and heat waves. The system represents an end-to-end approach that involves deploying a sensor network, analysing the data, creating visualisations in collaboration with farmers and delivering them to them in real-time via a website known as FarmDecisionTECH. We compared this network with previously available infrastructure, the results of which demonstrate that an in situ weather station was ∼5 C hotter than the closest available real-time weather station (∼20 km away from Clyde River) during a summertime heat wave. Heat waves can result in oysters dying due to exposure if temperatures rise above 30 C for extended periods of time (such as heat waves), which will mean a loss in income for the farmers; thus, this work stresses the need for accurate in situ monitoring to prevent the loss of oysters through informed farm management practices. Finally, an approach is proposed to present high-dimensional datasets captured from the sensor network to oyster farmers in a clear and informative manner.

Changes in Bacterial Communities During Treatment of Municipal Wastewater in Arctic Wastewater Stabilization Ponds

Wastewater stabilization ponds (WSPs) are commonly used to treat municipal wastewater in the Canadian Arctic. Bacterial community structure and functionality remain mostly uncharacterized for arctic WSPs, yet are presumed important for treatment outcomes during the 3-month summer treatment season with open water in the WSPs. The objective of this study was to investigate treatment performance and related temporal and spatial changes in the structure and putative function of bacterial communities during treatment of municipal wastewater in the WSPs of Pond Inlet and Clyde River, Nunavut over two consecutive summer treatment seasons. Influent raw wastewater contained a high organic load and large bacterial communities (~9 log 16S rRNA copies/mL) belonging mainly to Proteobacteria. Although designed to be facultative ponds, both WSPs remained anaerobic with neutral pH values (7.5–7.8) throughout the summer treatment season. Water quality data showed that nutrients [measured as carbonaceous biological oxygen demand (CBOD5)], total suspended solids, and total ammonia nitrogen were progressively reduced during treatment in the ponds as the summer progressed. The pond bacterial population size and species richness depended on the pond temperature (2–18°C), with 8.5 log 16S rRNA copies/mL and the largest alpha diversities (Shannon-Wiener index of 4-4.5) observed mid-season (late July). While the phylogenetic beta diversity in raw wastewater from the two locations remained similar, pond bacterial communities underwent significant (p < 0.05) changes to dominance of Comamonadaceae, Geobacteracea, and Porphyromonadaceae. Multivariate distance based redundancy analysis and predicted gene functionalities in the microbiota agreed with water quality results that microbial removal of nutrients (e.g., CBOD5) peaked in the middle of the summer coinciding with the treatment period with the highest pond temperatures. Information from this study will be useful for further development of models to predict biological treatment outcomes, which could be used to size and assess the feasibility of WSPs in extreme climates. Higher pond temperatures resulted in optimal biological processes and nutrient removal in the middle of the summer. While it is challenging to control environmental factors in a passive wastewater treatment system there are some design considerations that could be used to optimize temperature regimes, such as the depth of the pond.

CommunityFirst solutions for COVID-19: decolonising health crises responses

CommunityFirst solutions for COVID-19: decolonising health crises responses

What Do Land Acknowledgments Acknowledge?

Arctic char drying at a camp near Clyde River, Nunavut, Canada.Land acknowledgments—statements about the Indige­nous Peoples on whose lands others live and work—have become increasingly common in A...

First genetic evidence that invasive bullhead (Cottus L. 1758) in Scotland is of English origin and the difficulty of resolving the European Cottus species taxonomy.

The European bullhead (Cottus gobio) is widely distributed across Europe, and within the UK is native to England and Wales, where it is protected under the Habitats Directive. In Scotland, however, the species is considered invasive and thriving populations are recorded in the Forth and Clyde river catchments, and the Ale Water in the Scottish Borders. The genetic identity of the Scottish populations has not been established. There is also debate about the status of the European bullhead and its validity as single species, a species complex with several unresolved species, or distinct different species in its European distribution range. There is therefore a need to determine the taxonomy and likely source of the novel Scottish populations. Genetic analyses using cytochrome oxidase 1 (COI) mitochondrial DNA sequences were undertaken on specimens from the Forth and Clyde catchments, and combined with the results of morphological characteristics to provide a comprehensive assessment of the taxonomic classification for Scottish bullheads. There was considerable variation in morphological characteristics between populations within Scotland and a wider range of variability than previously recorded for English populations. Genetically the Scottish populations were very closely related to English specimens, supporting the hypothesis of introduction directly from England to Scotland. In terms of broader relationships, Scottish specimens are genetically more closely related to the ostensible species Chabot fluviatile Cottus perifretum, which has been suggested as one of a complex of species across Europe. Morphologically they exhibit characteristics on the spectrum between C. perifretum and C. gobio. There is an urgent need for the clarification of the taxonomy of Cottus sp(p). to avoid confusion in future publications, legislation and management practices relating to bullheads throughout the UK and Europe.

Seasonal Bioenergetic Changes in Saccostrea glomerata from Two Age Cohorts Farmed in Clyde River, Nsw, Australia

The study measured the mean and ranges of seasonal changes in whole body energetic values in two age groups of the Sydney rock oyster Saccostrea glomerata from the Clyde River, NSW, Australia. Oysters were collected over four seasons from two aquaculture-relevant age groups (24 and 36 mo) identified as key harvesting ages. Protein, lipid, glycogen energy equivalents, and electron transport system (ETS) activity were determined to identify seasonal changes in energy stores and consumption and to calculate cellular energy allocation. There were clear seasonal trends in energy changes, with glycogen and lipid energy equivalents highest in summer, decreasing to their lowest concentrations in autumn, and then slowly increasing through winter and into spring. Protein energy equivalents and ETS activity demonstrated an opposite trend, with increases in autumn and stable through the other seasons. Cellular energy allocation showed seasonal change, with highest values over summer, gradually decreasing in autumn and winter, and then starting to increase again in spring. These results indicate that seasonal changes in temperature, salinity, and food availability as well as reproductive cycles have a significant influence on S. glomerata energy storage and use. Developing an understanding of energetic responses in bivalves in response to environmental conditions can facilitate a more detailed understanding of growth potential and responses to aquaculture practices such as stocking density. As well, understanding natural energetic fluctuations allows a baseline for the assessment of other field-based stress responses such as anthropogenic contamination in S. glomerata.

Influence of environment on the pathogenesis of Ostreid herpesvirus-1 (OsHV-1) infections in Pacific oysters (Crassostrea gigas) through differential microbiome responses

The oyster microbiome is thought to contribute to the pathogenesis of mass mortality disease in Pacific oysters, associated with OsHV-1. As filter-feeders, oysters host a microbiota that can be influenced by the estuarine environment. This may alter susceptibility to OsHV-1 infections, causing variable mortality. This study aimed at: (1) differences in the microbiome of Pacific oysters with a common origin but grown in geographically distinct estuaries; (2) evaluating changes occurring in the microbiota, especially in Vibrio, and (3) differential responses of the oyster microbiome, in response to an OsHV-1 infection. Pacific oysters sourced from a single hatchery but raised separately in Patonga Creek, Shoalhaven River and Clyde River of NSW, Australia, were used and challenged with OsHV-1. The initial microbiome composition was different in the three batches and changed further, post-injection (p < 0.05). The Patonga oysters with the highest mortality also had higher OsHV-1 and Vibrio quantities compared to the other two batches (p < 0.05). The higher initial bacterial diversity in Patonga oysters decreased in moribund oysters which was not observed in the other two batches (p < 0.05). The microbiome of survivors of OsHV-1 infection and negative control oysters of two batches, did not show any changes with the relevant pre-challenged microbiome. A strong correlation was observed between the OsHV-1 and Vibrio quantities in OsHV-1 infected oysters (r = 0.6; p < 0.001). In conclusion, the Pacific oyster microbiome differed in different batches despite a common hatchery origin. Different microbiomes responded differently with a differential outcome of OsHV-1 challenge. The higher Vibrio load in oysters with higher OsHV-1 content and higher mortality, suggests a role in Vibrio in the pathogenesis of this mortality disease. This study provided insights of the potential of different estuarine environments to shape the Pacific oyster microbiome and how different microbiomes are associated with different outcomes of OsHV-1 infection.

Diagnosing Administrative Law: A Comment on Clyde River and Chippewas of the Thames First Nation

Diagnosing Administrative Law: A Comment on Clyde River and Chippewas of the Thames First Nation

Validation of Clyde River SuperDARN radar velocity measurements with the RISR-C incoherent scatter radar

Abstract. The study considers simultaneous plasma velocity measurements in the eastward direction carried out by the Clyde River (CLY) Super Dual Auroral Radar Network (SuperDARN) high-frequency (HF) radar and Resolute Bay (RB) incoherent scatter radar – Canada (RISR-C). The HF velocities are found to be in reasonable agreement with RISR velocities up to magnitudes of 700–800 m s−1 while, for faster flows, the HF velocity magnitudes are noticeably smaller. The eastward plasma flow component inferred from SuperDARN convection maps (constructed for the area of joint measurements with consideration of velocity data from all the radars of the network) shows the effect of smaller HF velocities more notably. We show that the differences in eastward velocities between the two instruments can be significant and prolonged for observations of strongly sheared plasma flows.

Organic geochemistry and petroleum potential of Permian outcrop and core samples from the southern Sydney Basin

Permian sediments occur throughout the southern Sydney Basin, exposed on the coastline south of Wollongong, and penetrated by various boreholes. This study uses outcrop samples and samples from three boreholes held by NSW Resources and Energy at the core library at Londonderry (Department of Mines Callala DDH1 [Callala-1] from near Callala Bay, Elecom Clyde River DDH07 [ECR-7] from near Nowra, and Elecom Clyde River DDH01 [ECR-1] from near Wingello). Formations analysed include the Berry Siltstone, Nowra Sandstone, Wandrawandian Siltstone, the Snapper Point Formation, the Pebbley Beach Formation and the Yarrunga Coal Measures. The objectives are to determine the depositional environment, organic matter inputs, thermal maturity and petroleum generation potential of these formations, which were deposited when Australia was close to the South Pole. The rocks at outcrop and in ECR-1 are in the early oil window, while rocks from near Jervis Bay (Callala-1, ECR-7) are in the gas window. Total organic carbon content is heterogeneous and varies from 0.2–6.7%. The rocks were deposited in oxic to suboxic depositional environments. The Wandrawandian Siltstone contains biomarkers dominated by very high amounts of diahopanes and diasteranes, whereas these biomarkers are of lower relative abundance in the other formations. This is suggestive of a clay-rich sediment in an oxic, acid-catalysed depositional environment, with enhanced diagenetic alteration of the biomarkers, or alternatively an unusual organic input. The Pebbley Beach and Snapper Point formations are characterised by biomarker distributions dominated by terrigenously sourced terpanes (e.g. C24 tetracyclic terpane and C19 tricyclic terpane), corroborating their deltaic and shallow marine depositional environments, respectively. In contrast, the Wandrawandian Siltstone contains dominantly C21, C23, and C24 tricyclic terpanes. The Pebbley Beach Formation contains high amounts of C29 relative to C28 and C27 steranes, also consistent with a dominant terrigenous input.

Optimal F Region Electron Density for the PolarDARN Radar Echo Detection Near the Resolute Bay Zenith

AbstractOperation of over‐the‐horizon radars comprising the Super Dual Auroral Radar Network (SuperDARN) relies on strong ionospheric refraction of high‐frequency (HF, f = 10–15 MHz) radiowaves such that in order to provide reliable coverage of a given geographic location, the working frequency has to be optimized with respect to the ionospheric conditions. In this work, joint observations of the Rankin Inlet, Inuvik, and Clyde River PolarDARN/SuperDARN HF radars near the Resolute Bay (RB) zenith, where the incoherent scatter radars that monitored the electron density distribution in the ionosphere, are used to assess the F region peak electron density required for HF echo detection near the RB zenith. We show that the echo occurrence rate increases with the electron density up to Ne ≈ (2 − 3) ⋅ 1011 m−3, and above this value, the occurrence rate saturates. Thus, optimum electron density for echo detection exist for every HF radar. The saturation effect is more pronounced for the Clyde River radar whose ranges of echo detection are smallest. The saturation in the dependence is reached at smaller densities for the Inuvik radar whose location is farthest from RB and for lower transmitting frequency of observations for every radar. The data presented suggest that having strong‐enough electron density in the ionosphere is the major factor for detection of HF echoes in winter or equinox.

Isolation of Imaqobactin, an Amphiphilic Siderophore from the Arctic Marine Bacterium Variovorax Species RKJM285.

The amphiphilic siderophore imaqobactin was isolated from the Arctic bacterium Variovorax sp. RKJM285, a strain isolated from marine sediment collected from an inlet near Clyde River, Nunavut, Canada. The 2D structure of imaqobactin was determined by a combination of LC-HRMS, MS/MS, and NMR spectroscopic methods. The absolute configuration of the depsipeptide core was determined by Marfey's analysis, and the relative configuration of the 4,7-diamino-3-hydroxy-2-methylheptanoic acid moiety was determined by NOESY and selective NOE experiments. The photoreductive properties of imaqobactin were tested and are discussed. Initial tests for antimicrobial and cytotoxic activity of imaqobactin were also performed, identifying moderate antimicrobial activity.

Mercury and persistent organic pollutants in native and invading forage species of the Canadian Arctic: Consequences for food web dynamics

Contaminant dynamics within Arctic marine food webs may be altered through the climate-driven northward invasions of temperate/boreal species. Here, we compare tissue concentrations of total mercury (THg) and legacy and emerging persistent organic pollutants (POPs) in native versus invading forage species sampled from 2012 to 2014 near Arviat, Clyde River, and Resolute Bay, NU, representing, low, mid- and high eastern Canadian Arctic regions, respectively. Concentrations of THg, legacy Σ-polychlorinated biphenyls (ΣPCB) and Σ-organochlorine (ΣOC) pesticides were detected in all forage species, whereas emerging halogenated flame retardants were detected in only a few individuals. Concentrations of major contaminant groups among regions did not vary for Arctic cod (Boreogadus saida), while for sculpin (Cottoidea) there was no clear latitudinal trend. Thus, considering interspecific variation, native sculpin and northern shrimp (Pandalus borealis) had the highest overall concentrations of THg (0.17 ± 0.02 and 0.21 ± 0.01 μg g−1 wet weight, respectively), ΣPCB (322 ± 35 and 245 ± 25 ng g−1 lipid weight (lw), respectively), and ΣOC (413 ± 38 and 734 ± 64 ng g−1 lw, respectively). Comparing the keystone native species, Arctic cod, to its ‘replacement’ species, capelin (Mallotus villosus) and sandlance (Ammodytes spp.), THg concentrations were higher in Arctic cod compared to capelin (p < 0.001), which was partly explained by differences in fish length. Conversely, capelin and sandlance had higher concentrations of most POPs than Arctic cod (p < 0.02). Neither feeding habitat (based on δ13C), trophic position (based on δ15N), nor fish length significantly explained these differences in POPs between Arctic cod, capelin and sandlance. Higher POPs concentrations, as well as variation in congener/compound patterns, in capelin and sandlance relative to Arctic cod seem, therefore, more likely related to a more “temperate”-type contaminant signature in the invaders. Nevertheless, the relatively small (up to two-fold) magnitude of these differences suggested limited effects of these ecological changes on contaminant uptake by Arctic piscivores.