Banks Island Research Articles

Late Wisconsinan glaciation and postglacial relative sea-level change on western Banks Island, Canadian Arctic Archipelago

The study revises the maximum extent of the northwest Laurentide Ice Sheet (LIS) in the western Canadian Arctic Archipelago (CAA) during the last glaciation and documents subsequent ice sheet retreat and glacioisostatic adjustments across western Banks Island. New geomorphological mapping and maximum-limiting radiocarbon ages indicate that the northwest LIS inundated western Banks Island after ~3114CkaBP and reached a terminal ice margin west of the present coastline. The onset of deglaciation and the age of the marine limit (22–40m asl) are unresolved. Ice sheet retreat across western Banks Island was characterized by the withdrawal of a thin, cold-based ice margin that reached the central interior of the island by ~14calkaBP. The elevation of the marine limit is greater than previously recognized and consistent with greater glacioisostatic crustal unloading by a more expansive LIS. These results complement emerging bathymetric observations from the Arctic Ocean, which indicate glacial erosion during the Last Glacial Maximum (LGM) to depths of up to 450m.

Population survey of Peary caribou (Rangifer tarandus pearyi) and muskoxen (Ovibos moschatus) on Banks Island, Northwest Territories, July 2010

We conducted a systematic aerial transect survey of Peary caribou (Rangifer tarandus pearyi) and muskoxen (Ovibus moschatus) on Banks Island, Northwest Territories, in July 2010. The population estimate of adult Peary caribou was 1097 ± 343 (95% Confidence Interval: CI), which is not significantly different from the 2005 estimate of 929 ± 289 (95% CI; P < 0.05). The current number, however, is a 4- to 9-fold decrease since the 1980s. The adult muskoxen population estimate was 36 676 ± 4031 (95% CI), which is significantly lower than the 2005 estimate of 47 209 ± 3997 (95% CI; P < 0.05).

Molecular phylogeny and historical biogeography of West Indian boid snakes (Chilabothrus)

The evolutionary and biogeographic history of West Indian boid snakes (Epicrates), a group of nine species and 14 subspecies, was once thought to be well understood; however, new research has indicated that we are missing a clear understanding of the evolutionary relationships of this group. Here, we present the first multilocus, species-tree based analyses of the evolutionary relationships, divergence times, and historical biogeography of this clade with data from 10 genes and 6256bp. We find evidence for a single colonization of the Caribbean from mainland South America in the Oligocene or early Miocene, followed by a radiation throughout the Greater Antilles and Bahamas. These findings support the previous suggestion that Epicrates sensu lato Wagler is paraphyletic with respect to the anacondas (Eunectes Wagler), and hence we restrict Epicrates to the mainland clade and use the available name Chilabothrus Duméril and Bibron for the West Indian clade. Our results suggest some diversification occurred within island banks, though most species divergence events seem to have occurred in allopatry. We also find evidence for a remarkable diversification within the Bahamian archipelago suggesting that the recognition of another Bahamian endemic species C. strigilatus is warranted.

Summer Sea Ice Concentration, Motion, and Thickness Near Areas of Proposed Offshore Oil and Gas Development in the Canadian Beaufort Sea – 2009

This study was motivated by the potential development of offshore oil exploration leases in the Canadian Southern Beaufort Sea, an area within the Inuvialuit Settlement Region. Sea ice concentration, extent, motion, and thickness data are vital to the success of potential oil operations in this region, and relevant data cannot be gleaned from larger-scale hemispheric studies. We therefore undertook regionally specific sea ice analyses in the southern Beaufort Sea during the summer drilling season (July, August, and September) in 2009 and over the long-term (1996 – 2010). On average, the Canadian oil lease areas contain mostly old sea ice during the drilling season and have not experienced significant decreasing trends in total or old sea ice. The average sea ice motion in the region for the period was anti-cyclonic at 20 – 25 cm·s-1, acting to transport sea ice southward toward the lease areas. Summer 2009 was used as a case study of regional ice concentration, motion, and thickness and to compare September sea ice thickness measurements to data collected in April 2009. In the summer of 2009, old sea ice was the predominant ice type in the lease areas. Sea ice motion was anti-cyclonic and faster than the long-term average, reaching 60 cm·s-1 west of Banks Island and across the north end of the lease areas. September 2009 sea ice thickness (mean = 1.03 m, σ = 0.97 m) was modal about the 0.20 – 0.29 m thickness bin. The sea ice thickness distri­bution was spatially variable, with the thickest ice occurring at the north end of the study area, in an area dominated by high old ice concentrations. Ice thicknesses greater than 10 m (the upper limit our instruments could measure) were encountered. Thinner sea ice predominated at the periphery of the core Beaufort Sea multi-year pack. Near the oil lease areas, the sea ice thickness distributions were shifted left on the histogram in comparison to those farther north, resulting in a greater proportion of relatively thick sea ice due to the thermodynamic loss of thinner (< 1.5 m) first-year ice during its southward movement. After enduring a summer’s melt, however, this thicker ice at the south end of the study region had thinned in comparison to the ice at the north end.

Gendered Inuinnait (Copper Inuit) landscapes of Banks Island’s northern interior, Arctic Canada, 17th–20th centuries a.d.

Archaeological survey data from the northern interior of Banks Island in Canada’s western Arctic builds upon traditional interpretations of past land use to explore the ways in which this landscape was perceived by different groups. The data confirm earlier archaeological, ethnographic, and oral history work which suggest that the area was occupied primarily in the summer months at two separate times in the past: the Palaeoeskimo period and the Inuinnait (Copper Inuit) period. The earlier occupation was less intensive than the latter and both were focused on muskox hunting. Drawing on ethnographic studies of the Inuit in both the early and late 20th centuries, and on the distribution of archaeological camp sites versus hunting sites, a reconstruction is made of the different ways in which men and women experienced and understood the survey area during Inuinnait times. It suggests that the main drainages formed important travel routes, and that while women’s knowledge of the region was concentrated along these corridors and in favorite camping places, men’s knowledge extended into hunting areas beyond their peripheries.

Cryogenic formation of brine and sedimentary mirabilite in submergent coastal lake basins, Canadian Arctic

Two informally named basins (Mirabilite Basins 1 and 2) along a submergent coastline on Banks Island, Canadian Arctic Archipelago, host up to 1m-thick accumulations of mirabilite (Na2SO4·10H2O) underlying stratified water bodies with basal anoxic brines. Unlike isostatically uplifting coastlines that trap seawater in coastal basins, these basins formed from freshwater lakes that were transgressed by seawater. The depth of the sill that separates the basins from the sea is shallow (1.15m), such that seasonal sea ice formation down to 1.6m isolates the basins from open water exchange through the winter. Freezing of seawater excludes salts, generating dense brines that sink to the basin bottom. Progressive freezing increases salinity of residual brines to the point of mirabilite saturation, and as a result sedimentary deposits of mirabilite accumulate on the basin floors. Brine formation also leads to density stratification and bottom water anoxia. We propose a model whereby summer melt of the ice cover forms a temporary freshwater lens, and rather than mixing with the underlying brines, it is exchanged with seawater once the ice plug that separates the basins from the open sea melts. This permits progressive brine development and density stratification within the basins.

Dynamic behaviour of the northwest Laurentide Ice Sheet and deposition of the latest Pleistocene Jesse Till moraine complex, Banks Island, Canadian Arctic Archipelago

Dynamic behaviour of the northwest Laurentide Ice Sheet and deposition of the latest Pleistocene Jesse Till moraine complex, Banks Island, Canadian Arctic Archipelago

Pleistocene horse remains from NW Banks Island, Canadian Arctic Archipelago: implications for long-term landscape evolution

Pleistocene horse remains from NW Banks Island, Canadian Arctic Archipelago: implications for long-term landscape evolution

Quaternary Glacial and Sea Level History of South Banks Island, NWT, Canada

Quaternary Glacial and Sea Level History of South Banks Island, NWT, Canada

Paleoglaciological insights from the age and morphology of the Jesse moraine belt, western Canadian Arctic

The Jesse moraine belt (350 km-long) was deposited by the northwest Laurentide Ice Sheet on Banks and Victoria islands in the western Canadian Arctic Archipelago during the last deglaciation. The moraine belt is composed of (ice-cored) controlled moraines that contrast markedly with adjacent glacial sediments deposited during preceding ice sheet retreat. More than 80 radiocarbon ages from fossil molluscs illustrate that deposition of the moraine belt was brief, occurring between 13.75 and 12.75 cal ka BP. The chronology demonstrates that moraine deposition was coeval with ice sheet drawdown and ice streaming on adjacent Victoria Island. Detailed geomorphic mapping demonstrates that the moraine belt is the product of a regional change in ice-marginal processes. This involved a predominantly cold-based ice margin giving way to polythermal bed conditions, which were conducive to widespread deposition of controlled moraines and ice stream bedforms. The expansion of warm-based thermal regimes in the northwest Laurentide Ice Sheet followed widespread ice sheet withdrawal from M'Clure Strait and western Amundsen Gulf. This suggests a re-equilibration of regional ice divides in response to rapidly changing ice sheet margins and surface gradients. The reconstructed dynamical behavior of the northwest Laurentide Ice Sheet provides new insights regarding ice sheet responses to late-glacial climate and relative sea level change, among other variables.

MOLECULAR PRESERVATION OF CENOZOIC CONIFER FOSSIL LAGERSTATTEN FROM BANKS ISLAND, THE CANADIAN ARCTIC

Abstract The molecular preservation of exceptionally preserved conifer needles from middle Miocene and Pliocene deposits on Banks Island, Canada, was investigated using pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS). Solvent-extracted residues from Miocene Larix, Glyptostrobus, and Pinus, Pliocene Picea, and their associated bulk material, yielded abundant polysaccharide pyrolysis products, such as 2-methylfuran, 2-furaldehyde, and levoglucosan, indicating excellent molecular preservation. Comparison of pyrolysates of individual plant taxa and bulk material from the same deposits revealed the dominance of particular plant taxa in these high latitude floras. Comparison with fossil Lagerstatten from Ellesmere Island (late Paleocene) and Axel Heiberg Island (middle Eocene), both in the Canadian Arctic Archipelago, and Clarkia in Idaho, United States (middle Miocene), demonstrated that the quality of molecular preservation of material from Banks Island is similar to that of Axel Heiberg Island and ...

The Bacterial Community of the Lithistid Sponge Discodermia spp. as Determined by Cultivation and Culture-Independent Methods

The marine lithistid sponge Discodermia spp. (Family Theonellidae) contains many types of associated bacteria visible in the mesohyl while biofilms cover the pinacoderm. This study determined the identity of bacteria associated with members of the genus Discodermia using microbial culture, 16S rRNA gene clone libraries and fluorescence in situ hybridization. Four samples of Discodermia spp. were collected at depths between 24-161m near Grand Bahama Island and Cay Sal Bank, Bahamas. A total of 80 unique isolates and 94 different clone sequences from at least eight bacterial classes were obtained. It appeared that Discodermia spp. may have a core community of bacteria that is common to all sponges of this genus. Species of at least six different classes of bacteria were regularly found in most of the sponge specimens collected, irrespective of collection depth or location. This indicates that a diverse spectrum of bacteria is associated with lithistid sponges irrespective of the transient seawater community that enters the sponge.

Annual cycles of pCO2sw in the southeastern Beaufort Sea: New understandings of air‐sea CO2 exchange in arctic polynya regions

From 23 October 2007 to 1 August 2008, we made continuous measurements of sea surface partial pressure of CO2 (pCO2sw) in three regions of the southeastern Beaufort Sea (Canada): the Amundsen Gulf, the Banks Island Shelf, and the Mackenzie Shelf. All three regions are seasonally ice covered, with mobile winter ice and an early spring opening that defines them as polynya regions. Amundsen Gulf was characterized by undersaturated pCO2sw (with respect to the atmosphere) in the late fall, followed by an under‐ice increase to near saturation in winter, a return to undersaturation during the spring, and an increase to near saturation in summer. The Banks Island Shelf acted similarly, while the Mackenzie Shelf experienced high supersaturation in the fall, followed by a spring undersaturation and a complex, spatially heterogeneous summer season. None of these patterns are similar to the annual cycle described or proposed for other Arctic polynya regions. We hypothesize that the discrepancy reflects the influence of several previously unconsidered processes including fall phytoplankton blooms, upwelling, winter air‐sea gas exchange, the continental shelf pump, spring nutrient limitation, summer surface warming, horizontal advection, and riverine input. In order to properly predict current and future rates of air‐sea CO2 exchange in such regions, these processes must be considered on a location‐by‐location basis.

The dynamics of linguistic diversity: egalitarian multilingualism and power imbalance among northern Vanuatu languages

The Torres and Banks Islands, two small archipelagos of northern Vanuatu, are home to 9400 inhabitants and to 17 distinct languages. With an average of 550 speakers per language, this region constitutes an extreme case of the linguistic fragmentation which is typically observed throughout Melanesia. This study presents the linguistic diversity of that area, examines its social underpinnings and outlines its historical dynamics. These islands form an integrated network where a variety of social forces interact, sometimes in conflicting ways. A long lasting bias toward cultural differentiation of local communities has led historically to the linguistic mosaic observable today. This traditional fostering of diversity was correlated with a principle of egalitarian multilingualism. But while these ancient social attitudes have survived to this day, the linguistic diversity of northern Vanuatu has already begun to erode, due to various recent social changes. These changes have reshaped the language ecology of the region and already resulted in the partial loss of earlier linguistic diversity. While northern Vanuatu is still linguistically diverse today, the increased imbalance of power among languages potentially makes the weaker varieties vulnerable in the decades to come.

Introduction to the special issue on the biology of the circumpolar flaw lead (CFL) in the Amundsen Gulf of the Beaufort Sea (Arctic Ocean)

The sea-ice cover of the Arctic Ocean is decreasing in areal extent and volume more rapidly than model predictions of its response to continued warming of earth’s lower atmosphere. Reflecting this decrease is the spatial and temporal widening of the circumpolar flaw lead, a zone of open water and unconsolidated ice along the coastlines of the shallow seas that surround the deep Arctic Ocean basins. As part of the International Polar Year, the Circumpolar Flaw Lead System Study deployed the research icebreaker Amundsen from October 2007 to August 2008 in the flaw lead segment bordering Banks Island in the Canadian Beaufort Sea. With participation from Canada, the USA, Spain, Germany, China, Russia, the UK, Norway, Belgium, the Netherlands, France, and Sweden, the multi-disciplinary overwintering expedition logged 9,812 scientist-days in an effort to decipher key aspects of the ecosystem of the flaw lead. Highlights of the scientific achievements documented in this special issue on the biology of the circumpolar flaw lead system help to capture the depth, breadth, and novelty of this remarkable exploration.

LIDAR measurements of Arctic boundary layer ozone depletion events over the frozen Arctic Ocean

[1] A differential absorption light detection and ranging instrument (Differential Absorption LIDAR or DIAL) was installed on-board the Canadian Coast Guard Ship Amundsen and operated during the winter and spring of 2008. During this period the vessel was stationed in the Amundsen Gulf (71°N, 121–124°W), approximately 10–40 km off the south coast of Banks Island. The LIDAR was operated to obtain a continuous record of the vertical profile of ozone concentration in the lower atmosphere over the sea ice during the polar sunrise. The observations included several ozone depletion events (ODE's) within the atmospheric boundary layer. The strongest ODEs consisted of air with ozone mixing ratio less than 10 ppbv up to heights varying from 200 m to 600 m, and the increase to the background mixing ratio of about 35–40 ppbv occurred within about 200 m in the overlying air. All of the observed ODEs were connected to the ice surface. Back trajectory calculations indicated that the ODEs only occurred in air that had spent an extended period of time below a height of 500 m above the sea ice. Also, all the ODEs occurred in air with temperature below −25°C. Air not depleted in ozone was found to be associated with warmer air originating from above the surface layer.

Discovery and Description of the “Davtiani” Morphotype for Teladorsagia boreoarcticus (Trichostrongyloidea: Ostertagiinae) Abomasal Parasites In Muskoxen, Ovibos moschatus, and Caribou, Rangifer tarandus, from the North American Arctic: Implications for Parasite Faunal Diversity

Collections to explore helminth diversity among free-ranging ungulates in the North American Arctic revealed the occurrence of a third male, or " davtiani ," morphotype for Teladorsagia boreoarcticus . Designated as T. boreoarcticus forma (f.) minor B, the males occurred with T. boreoarcticus f. major and T. borearcticus f. minor A in endemic populations of muskoxen (Ovibos moschatus wardi) and barrenground caribou (Rangifer tarandus groenlandicus) on Victoria Island, Nunavut, Canada, and in muskoxen and Peary caribou ( Rangifer tarandus pearyi ) on Banks Island, Northwest Territories, Canada. These specimens differ from conspecific morphotypes in the structure of the genital cone and Sjöberg's organ. Relative to T. boreoarcticus f. minor A, specimens of T. boreoarcticus f. minor B are consistently smaller, and mean dimensions for the bursa and spicules do not overlap. The robust spicules are similar in form, particularly in the relative length of the dorsal and ventral processes, but mean total length is substantially less in specimens of T. boreoarcticus f. minor B. Differences that distinguish the minor morphotypes of T. boreoarcticus parallel those demonstrated for the T. trifurcata and T. davtiani morphotypes in association with T. circumcincta sensu stricto. New host and geographic records include the 3 morphotypes of T. boreoarcticus in muskoxen and Peary caribou from Banks Island and in barrenground caribou from Victoria Island. Recognition of the ubiquitous nature of cryptic species emphasizes the need to effectively develop and use our collections-based resources and museum archives to build a robust understanding of the biosphere. Field inventory should include provisions for integrative approaches that preserve specimens suitable for comparative morphology, multi-faceted molecular investigations, and population genetics.

Benthic Marine Fauna and Flora of Two Nearshore Coastal Locations in the Western and Central Canadian Arctic

Baseline data on nearshore benthic macrofauna and flora assemblages are necessary for successful environ­mental monitoring in the Arctic, where major climate and industrial changes are underway, yet to date these environments remain understudied. This study used bottom video and benthic grab samples to compare shallow benthic marine (1 – 40 m) floral and faunal distribution and composition in two nearshore locations in the Canadian Arctic with different geomorphic settings. Sachs Harbour, located on southwestern Banks Island, has a submergent soft-sediment shoreline with locally rapid coastal erosion, while Gjoa Haven, located on southeastern King William Island, has an emergent shoreline dominated by coarse ice-contact Quaternary sediments with little to no coastal erosion. Gjoa Haven’s sediment-starved, heterogeneous nearshore area contributes to a more diverse macroalgal flora than is found at Sachs Harbour, where a continuous supply of sand and mud from thermally driven coastal erosion and muddy runoff produces a more homogeneous nearshore environment. Seventy-four species (10 macroalgae, 64 macrofauna) were recorded from southwestern Banks Island and 65 species (26 macroalgae, 39 macrofauna) from southeastern King William Island. Species composition differed greatly among locations and varied significantly among substrate and depth classes for grab- and video-sampled biota at Gjoa Haven and among depth classes for bottom video biota at Sachs Harbour. Faunally barren, shallow, mobile sand sheets were the dominant habitat sampled in Sachs Harbour. Gjoa Haven’s habitats differed significantly along a depth gradient, with sand and gravel substrates covered by Fucus sp. at depths shallower than 10 m and muddy substrates with filamentous green algae, Coccotylus truncatus, and cerianthid anemones inhabiting water down to 40 m.

Vegetation of zonal patterned‐ground ecosystems along the North America Arctic bioclimate gradient

AbstractQuestion: How do interactions between the physical environment and biotic properties of vegetation influence the formation of small patterned‐ground features along the Arctic bioclimate gradient?Location: At 68° to 78°N: six locations along the Dalton Highway in arctic Alaska and three in Canada (Banks Island, Prince Patrick Island and Ellef Ringnes Island).Methods: We analysed floristic and structural vegetation, biomass and abiotic data (soil chemical and physical parameters, the n‐factor [a soil thermal index] and spectral information [NDVI, LAI]) on 147 microhabitat relevés of zonal‐patterned‐ground features. Using mapping, table analysis (JUICE) and ordination techniques (NMDS).Results: Table analysis using JUICE and the phi‐coefficient to identify diagnostic species revealed clear groups of diagnostic plant taxa in four of the five zonal vegetation complexes. Plant communities and zonal complexes were generally well separated in the NMDS ordination. The Alaska and Canada communities were spatially separated in the ordination because of different glacial histories and location in separate floristic provinces, but there was no single controlling environmental gradient. Vegetation structure, particularly that of bryophytes and total biomass, strongly affected thermal properties of the soils. Patterned‐ground complexes with the largest thermal differential between the patterned‐ground features and the surrounding vegetation exhibited the clearest patterned‐ground morphologies.Conclusions: Characterizing the composition and structure of small‐scale plant communities growing on distinctive microhabitats within patterned‐ground complexes was necessary to understand the biological and physical controls of vegetation on patterned‐ground morphology. Coarser‐scale vegetation units, referred to here as ‘zonal patterned‐ground vegetation complexes’ (groups of patterned‐ground plant communities within zonal landscapes), were useful for landscape and regional‐level comparisons and for extrapolation of information collected at plot scales to larger regions. Vegetation maps of the representative landscapes in each subzone were needed for extrapolation. Different growth characteristics of plants growing in northern and southern parts of the gradient have an important effect in stabilizing highly frost‐active soils. A conceptual diagram summarizes the interactions between vegetation and patterned‐ground morphology along the Arctic climate gradient.

U-Pb-Hf characterization of the central Coast Mountains batholith: Implications for petrogenesis and crustal architecture

We present U-Pb geochronologic and Hf isotopic data from 29 plutonic samples within the Coast Mountain batholith, north-coastal British Columbia and southeast Alaska. Hf isotopic values do not correlate with age or variation in magmatic flux, but rather they increase systematically from west (e_(Hf)[t] = +2 to +5) to east (e_(Hf)[t] = +10 to +13) in response to changing country rock assemblages. By comparing our pluton Hf data with previously reported Nd-Sr and detrital zircon characteristics of associated country rocks, we identify three crustal domains in an area where crustal affinity is largely obscured by metamorphism and voluminous pluton intrusion: (1) a western domain, emplaced into continental-margin strata of the Banks Island assemblage; (2) a central domain, emplaced into the Alexander terrane; and (3) an eastern domain, underlain by the Stikine terrane and its inferred metamorphic equivalents. Between the interpreted Alexander and Stikine terranes, there is a zone of variable e_(Hf)(t) (+2 to +13) that coincides with the suture zone separating inboard (Stikine and Yukon-Tanana) from outboard (Alexander and associated) terranes. This variation in e_(Hf)(t) values apparently results from the structural imbrication of juvenile (Alexander and Stikine) and evolved (Yukon-Tanana) terranes along mid-Cretaceous thrust faults and the latest Cretaceous–early Tertiary Coast shear zone. Shifts in the Hf values of plutons across inferred terranes imply that they are separated at lower- to midcrustal levels by steep boundaries. Correlation between these Hf values and the isotopic character of exposed country rocks further implies the presence of those or similar rocks at magma-generation depths.