Cornwallis Island Research Articles

Snowmelt sources of methylmercury to high arctic ecosystems.

Mercury in humans and other top predators living in the Arctic is present at elevated levels. Since only methylmercury (MeHg) bioaccumulates in food chains, sources of MeHg need to be identified. Recently, wetlands in the High Arctic were found to produce MeHg, and this was confirmed in laboratory soil incubations. In the present study both wetlands and snowmelt water were evaluated as sources of MeHg to Arctic ecosystems in Nunavut. Three substudies took place on Cornwallis Island, and one took place on Ellesmere Island. First, the effect of wetland presence in lake watersheds was evaluated by comparing four lakes with wetlands present to four lakes without wetlands present. Next, two individual wetlands were spatially and temporally investigated. Finally, three basin tributaries were evaluated for snowmelt MeHg sources. Catchments on Cornwallis Island with wetlands did not have an observable effect on MeHg levels in downstream lake water, but the wetland on Ellesmere Island contributed significant MeHg. In contrast, calculated yields of MeHg in tributaries draining snowmelt on Cornwallis Island were higher (ca. 1.5 mg km(-2) day(-1)) than those measured in temperate catchments characterized by wetlands. Methylmercury and total Hg concentrations in lakes, wetlands, and basin tributaries showed a strong temporal trend that corresponded to inputs from snowmelt water in late spring. This study revealed that wetland export of MeHg to downstream Arctic lakes is site dependent, and snowmelt water was the most significant source of MeHg to Arctic ecosystems located on Cornwallis Island.

Devon Island's Oriented Landforms as an Analog to Illinois-Type Paha

Illinois-type paha are unusual regional landforms located in northwestern Illinois, USA, consisting of inactive, oriented, oblong ridges composed of either loess or bedrock capped by loess. A recent study reidentified the paha of Illinois as relict oriented, snowmelt interfluves, formed by erosion from snowdrifts or snow dunes occupying oriented valleys alternating with inter-valley ridges during the cold phase(s) of the Pleistocene Epoch. Devon Island, located in the high Arctic, exhibits similar regional, oriented inter-valley ridges and adjacent oriented valleys with the added feature of overlying, oriented snowbanks or snow dunes. The similarities between both regional landforms include morphology, dimensions, parallelism, orientation to the (paleo)wind; and the fact that the oriented dissection was formed irrespective of the steepest direction of the general slope. Oriented nival landforms with the same peculiar characteristics also exist on Resolute, Cornwallis Island, adjacent to Devon Island. Nivation compounded by indirect influence of the wind is proposed as the causal agent for all of the previously mentioned landforms.

Validity and composition of the Silurian trilobite genera Borealarges and Dicranogmus, with new species from the Canadian Arctic

New silicified material from Arctic Canada demonstrates that the lichid trilobite genera Borealarges and Dicranogmus, recently claimed to be synonyms, are independent groups with no close phylogenetic connection to one another. Dicranogmus has been known mainly from cranidia alone; prior association of librigenae and pygidia with the Arctic Canadian species D. skinneri has been queried. This association is correct beyond reasonable doubt, based on description of new material of both D. skinneri and a new species. Three new species of Borealarges are related to B. tuckerae Adrain 1994. Cladistic analysis supports the monophyly of this species group. Pending further new information, however, the group is retained within the genus Borealarges. The stratigraphic range of the species group is extended from the lower Wenlock (Sheinwoodian) to upper Ludlow (Ludfordian) by the discovery of a rare species in the Douro Formation of Cornwallis Island, Arctic Canada. New taxa from the Wenlock of the Cape Phillips Formation, Arctic Canada, include Dicranogmus wynni, Borealarges nicoae, B. warholi, and B. yulei.

Status, population fluctuations and ecological relationships of Peary caribou on the Queen Elizabeth Islands: Implications for their survival

The Peary caribou (Rangifer tarandus pearyi) was recognized as 'Threatened' by the Committee on the Status of Endangered Wildlife in Canada in 1979 and 'Endangered' in 1991. It is the only member of the deer family (Cervidae) found on the Queen Elizabeth Islands (QEI) of the Canadian High Arctic. The Peary caribou is a significant part of the region's biodiversity and a socially important and economically valuable part of Arctic Canada's natural heritage. Recent microsatellite DNA findings indicate that Peary caribou on the QEI are distinct from caribou on the other Arctic Islands beyond the QEI, including Banks Island. This fact must be kept in mind if any translocation of caribou to the QEI is proposed. The subspecies is too gross a level at which to recognize the considerable diversity that exists between Peary caribou on the QEI and divergent caribou on other Canadian Arctic Islands. The Committee on the Status of Endangered Wildlife in Canada should take this considerable diversity among these caribou at below the subspecies classification to mind when assigning conservation divisions (units) to caribou on the Canadian Arctic Islands. In summer 1961, the first and only nearly range-wide aerial survey of Peary caribou yielded a population estimate on the QEI of 25 845, including about 20% calves. There was a strong preference for range on the western QEI (WEQI), where 94% (24 363) of the estimated caribou occurred on only 24% (ca. 97 000 km2) of the collective island-landmass. By summer 1973, the overall number of Peary caribou on the QEI had decreased markedly and was estimated at about 7000 animals. The following winter and spring (1973-74), the Peary caribou population declined 49% on the WQEI. The estimated number dropping to <3000, with no calves seen by us in summer 1974. Based on estimates from several aerial surveys conducted on the WQEI from 1985 to 1987, the number of Peary caribou on the QEI as a whole was judged to be 3300-3600 or only about 13-14% of the 1961 estimate. After a partial recovery in the late 1980s and early 1990s, Peary caribou on the WQEI declined drastically between 1994 and 1997 and were estimated at an all-time known low of about 1100 animals by summer 1997. The number of Peary caribou on the QEI in summer 1997 was likely no more than 2000-2400 or only 8-9% of the 1961 estimate. The four known major die-offs of Peary caribou on the WQEI between 1973 and 1997 occurred during winter and spring periods (1 Sep-21 Jun) with significantly greater (P<0.005) total snowfall, when compared to the long-term mean obtained from 55 caribou-years (1 Jul-30 Jun), 1947/48-2001/02, of weather records from Resolute Airport on Cornwallis Island. Of ecological significance is that the die-offs occurred when the caribou were at low mean overall densities and involved similar high annual rates of loss among muskoxen (Ovibos moschatus). All of the available evidence indicates that Peary caribou (and muskoxen) on the QEI experienced die-offs from prolonged, under-nutrition (starvation) caused by relative unavailability of forage-the forage was there but it was inaccessible to the caribou due to snow and/or ice cover. We cannot control the severe weather that greatly restricts the forage supply but we should try to reduce the losses of Peary caribou from other sources-humans, predators and competitors.

Thermo-hydrological Responses to an Exceptionally Warm, Dry Summer in a High Arctic Environment

1998 was a very warm year for Canada and the High Arctic was no exception. A typical area was Resolute, Cornwallis Island, Nunavut, where the thaw season was extended and the thawing degree-days were larger than normal. The warm summer was accompanied by early spring melt and low rainfall. This study documents the thermo-hydrological responses including warming of the top soil, deepening of the active layer, alteration of the evaporation pattern, adjustment of the water table positions and runoff. The presence of semi-permanent snowbanks and patchy wetlands buffer some local sites from the warm and dry summer conditions. This and other studies show that the cryospheric and hydrologic systems may or may not recover quickly from the year to year variations in the climate, depending on how readily the storages (snow, ice and basin moisture) can be replenished. In view of the cumulative effects of storage depletion under climatic warming, short-term studies on thermo-hydrological behaviour in the Arctic provide a useful but insufficient analogue to capture the climatic change impacts.

Diatom response to recent climatic change in a high arctic lake (Char Lake, Cornwallis Island, Nunavut)

From 1968 to 1972, Char Lake (Resolute Bay, Cornwallis Island, Canadian High Arctic) was the site of a large-scale limnological study conducted under the auspices of the International Biological Programme. However, since that time, very little research has been done on the lake. We sampled Char Lake from 1992 to 2000 for a suite of physical, chemical, and biological variables. In general, there were no major differences between our water quality data and those collected 30 years earlier, showing that Char Lake is still oligotrophic, slightly alkaline, and dilute. However, a diatom-based paleolimnological analysis revealed that a subtle, yet distinct species assemblage shift has occurred beginning around 1987. The timing of this species shift does not correspond to the deposition of atmospherically transported persistent organic pollutants into the lake (beginning in the early 1950s) or to minor disturbances within its catchment (early 1970s). Instead, these subtle diatom changes are consistent with recent climatic changes during 1988–1997 (as documented by local meteorological measurements), and are likely related to reduced summer ice cover and a longer growing season.

Tracking recovery in a eutrophied high arctic lake (Meretta Lake, Cornwallis Island, Canadian Arctic) using periphytic diatoms

Tracking recovery in a eutrophied high arctic lake (Meretta Lake, Cornwallis Island, Canadian Arctic) using periphytic diatoms

Temporal patterns of suspended sediment yield following moderate to extreme hydrological events recorded in varved lacustrine sediments

AbstractA 487‐year annually laminated (varved) sediment record from Nicolay Lake, Cornwall Island, in the Canadian High Arctic was evaluated to determine the impact that years with high sediment yields had on sediment yields in subsequent years. All of the 40 largest years showed evidence for increased sediment yield in the subsequent 10–30 years. The positive anomalies in lagging years were approximately scaled according to the size of the initiating year, although many intermediate years (25‐ to 100‐year recurrence) showed weak or variable responses. The smallest events considered (10‐ to 25‐year recurrence) showed a consistent, but low‐amplitude response. Additionally the 10‐year events revealed frequent negative sediment yield anomalies in the preceding decade. This behaviour was interpreted as a frequent sediment activation cycle initiated by the modest year, and leading to sediment yield hysteresis lasting 15–25 years. The largest years (greater than 50‐year recurrence) showed consistently above‐average sediment yields in the preceding decade, in part due to the frequent occurrence of moderate (Q10) years. It is hypothesized that temporary storage of sediment and previous initiation of erosion sites resulted in extraordinary sediment yields during intense summer rainfall events. This study demonstrates the potential use of varved lake sediment records to improve our understanding of long‐term sediment dynamics. These records present an opportunity to further develop and test sediment dynamic and routing models to gain insight into the interaction of time and space in fluvial and sediment delivery processes. Copyright © 2002 John Wiley & Sons, Ltd.

Sir John Franklin's last arctic expedition: a medical disaster.

Sir John Franklin's last arctic expedition: a medical disaster.

Tracking recent recovery from eutrophication in a high arctic lake (Meretta Lake, Cornwallis Island, Nunavut, Canada) using fossil diatom assemblages

Meretta Lake (Resolute Bay, Cornwallis Island, Nunavut, Canada) is a high arctic lake that received raw sewage for almost 50 years from the Canadian Department of Transport Base. The lake was sampled from 1968–72 during the International Biological Programme, as part of the Char Lake Project. As the number of users at the Transport Base declined throughout the 1990s, so too did the lake's nutrient levels, and Meretta Lake is now classified as oligotrophic. A previous diatom-based paleolimnological study revealed marked species assemblage shifts coincident with sewage inputs beginning in the late 1940s; however, because the core was taken at a time when nutrient levels were still relatively high (i.e., 1993), the diatom record did not yet track any signs of recovery. In this present study, we examined fossil diatom assemblages from a sediment core taken in 2001. Our results indicate a shift to the pre-impact diatom assemblages in the most recent sediments, indicating that the paleolimnological record is tracking the decreased nutrient inputs to this high arctic lake, and confirms that no significant lags exist in these largely ice-covered lakes.

Characterization of high arctic stream diatom assemblages from Cornwallis Island, Nunavut, Canada

Distinct diatom assemblages often characterize stream habitats, providing the potential to reconstruct past precipitation, snowmelt, and streamflow levels in high arctic watersheds by analyzing fossil assemblages preserved in downstream lake sediments. Diatom assemblages were studied from seven streams and two rivers surrounding Lake Sophia, Cornwallis Island, Nunavut, Canada (75°06' N, 93°36' W). A total of 64 diatom taxa were identified from epilithic and epiphytic assemblages in these lotic habitats. Of these, certain diatom taxa exhibited clear microhabitat preferences. Hannaea arcus (Ehrenberg) Patrick, Achnanthes minutissima (Kützing) Hustedt, Achnanthes petersenii Hustedt, and Meridion circulare (Greville) Agardh were the most common taxa on epilithic substrates, and as a group made up 61–95% of the diatom epilithon. Achnanthes taxa (mainly A. petersenii and A. minutissima) were the dominant taxa in moss habitats, representing between 45 and 73% of the diatom epiphyton. The relative abundance of H. arcus in epilithic habitats was negatively correlated with water temperature (r2= 0.71, n = 8). Hannaea arcus was found in greater abundances in cool, fast-flowing streams. This apparent correlation may more closely reflect current speed, which is inversely correlated to temperature in these streams. When these streams discharge into lake basins, the characteristic stream diatoms H. arcus and M. circulare are deposited in lakes. These diatom taxa have the potential to infer past streamflows using paleolimnological techniques.Key words: diatoms, arctic, stream, rheophilous, Lake Sophia, Hannaea arcus.

Streamflow and Suspended Sediment Transfer to Lake Sophia, Cornwallis Island, Nunavut, Canada

To ascertain the climatic controls on sediment transport to Lake Sophia, Cornwallis Island, Nunavut, Canada, we made detailed hydrological and meteorological measurements in the Sophia River watershed through the 1994 melt season. Streamflow and suspended sediment transport are limited, on an annual time scale, by the supply of snow and sediment in the watershed. Suspended sediment yield from the watershed was only 0.46 t km−2, which is lower than any previously published yield for a stream in the High Arctic. Snowmelt runoff accounted for 88% of the annual suspended sediment load, whereas 6 and 9% were transported in response to a slushflow event and summer rainfall, respectively. These measurements provide no direct evidence that modern-day sediment delivery to Lake Sophia is related to fluctuations in air temperature, which has implications for the paleoenvironmental signal preserved in Lake Sophia's laminated sediments. We suggest that on-site sediment transport studies are necessary to establish the relationships among geology, geography, climate, and hydrology unique to each watershed-lake system and need to be an integral part of any calibration attempt. Additional years of data are needed however to define the interannual variability of streamflow and sediment transport in response to climate.

Streamflow and Suspended Sediment Transfer to Lake Sophia, Cornwallis Island, Nunavut, Canada

To ascertain the climatic controls on sediment transport to Lake Sophia, Com­ wallis Island, Nunavut, Canada, we made detailed hydrological and meteorolog­ ical measurements in the Sophia River watershed through the 1994 melt season. Streamflow and suspended sediment transport are limited, on an annual time scale, by the supply of snow and sediment in the watershed. Suspended sediment yield from the watershed was only 0.46 t k:m- 2 , which is lower than any previously published yield for a stream in the High Arctic. Snowmelt rgnoff accounted for 88% of the annual suspended sediment load, whereas 6 and 9% were transported in response to a slushflow event and summer rainfall, respectively. These mea­ surements provide no direct evidence that modem-day sediment delivery to Lake Sophia is related to fluctuations in air temperature, which has implications for the paleoenvironmental signal preserved in Lake Sophia's laminated sediments. We suggest that on-site sediment transport studies are necessary to establish the re­ lationships among geology, geography, climate, and hydrology unique to each watershed-lake system and need to be an integral part of any calibration attempt. Additional years of data are needed however to define the interannual variability of streamflow and sediment transport in response to climate.

Late Wisconsinan Glaciation of the Central Sector of the Canadian High Arctic

Geomorphic and chronological evidence from Cornwall Island in the Canadian High Arctic Archipelago provides direct evidence for the age and dynamics of the center and northern flank of the Innuitian Ice Sheet that covered the islands during the Late Wisconsonian glacial maximum. Dispersal of erratics and glacial landforms indicate that ice flowed north across the island and converged with ice flowing northwest from Norwegian Bay. Cornwall Island was initially deglaciated at 9000 14C yr B.P. in near synchrony with widely separated sites in adjacent parts of the archipelago. This regional chronology suggests rapid breakup of a marine-based Innuitian Ice Sheet that was destabilized by rapid eustatic sea-level rise and ice thinning during the early Holocene. This evidence provides strong support for a recently proposed ice divide spanning the central part of the Canadian High Arctic and indicates that most, if not all, of the region was glaciated during the Late Wisconsinan.

Hydrological Response of a Patchy High Arctic Wetland

High Arctic patchy wetlands are ecological oases in a polar desert environment and are vulnerable to climatic warming. At present, understanding of their responses to external factors (climate and terrain) is limited. This study examines a wetland located in a topographic depression maintained by seasonal snowmelt, ground ice melt and lateral inflows. The wetland is located on Cornwallis Island, Nunavut, Canada. Hydrological, climatological and soil observations were made over several summers with different weather conditions. The summers of 1996 and 1997 were cool and wet but the summer of 1998 was warm and dry. The melt in 1996 was rapid due to rain on snow events and only lasted six days. Deeper snow in 1997 prolonged the melt season to 18 days. A shallow snow-cover in 1998 and early melt depleted the snow by early June. Surface, groundwater and storage fluctuations in the wetland were dictated by snowmelt, rainfall, evaporation loss from the wetland and lateral inputs which in turn were controlled by the melting of the late-lying snow storage in the catchment. Soil factors influence the spatial variations in ground thaw which affects the surface and subsurface flow. Streamflow response of the wetland reflects a nival regime and augmentation of streamflow thoughout the summer season in all three years is supported by multiple water sources: ground ice melt and suprapermafrost water from a large late-lying snowpack. Overall, this study suggests that the survival of some patchy wetlands depends on their interaction with the surrounding basin, with a dependency probably being more important during warm and dry seasons.

Late Silurian trilete spores from northern Jiangsu, China

The Late Silurian is generally considered to a particular significant key period in the study of early land vascular plants. A trilete spore assemblage of the Upper Silurian is described from northern Jiangsu, China. This assemblage comprises 11 genera and 20 species of trilete spores (including laevigate, apiculate, perinotrilite, patinate, rarely distally murornate and equatorially crassitate, and three indeterminate trilete miospores forms). It has similarities to those described from coeval assemblages from around the world (e.g., England and South Wales; Tripolitania, Libya; Cornwallis Island, Canadian Arctic; Northwest Spain). The rare cryptospore, only one specimen ( Tetrahedraletes sp.) had been found to be associated with the Chinese trilete spore assemblage. The discovery of the trilete spores from Late Silurian rocks indicates the existence of early land plants, some possibly vascular, at that time in northern Jiangsu, China.

Sediment dynamics and the transport of suspended matter in the upstream area of Lake St. Francis

A long-term project was initiated in autumn 1994 to monitor the suspended matter (SM) in the upstream area of Lake St. Francis. Over a 32-month period, 190 SM samples were collected at six study sites while conductivity and current velocity measurements were made to study resuspension and transport of SM. Weather data from a nearby station and daily discharge rates for the St. Lawrence River were also utilised. Overall, the study shows that the SM load in the central portion of Lake St. Francis is not evenly distributed. On the northern side of the lake, the SM load is mainly a function of the SM load carried by the St. Lawrence River waters coming from the Great Lakes. On the southern side, an important contribution to the SM load comes from sediment resuspension and from the local tributaries. Calculations show that wave action is likely to resuspend surficial sediments in depths shallower than 2 m, a surface area estimated to be 32-35 km2 between Cornwall Island and Thompson Basin. Also, important fluctuations of the south shore tributaries' winter discharge are thought to contribute to sediment resuspension and redistribution of contaminants such as mercury and polychlorinated biphenyls.

Eutrophication and recovery in the High Arctic: Meretta Lake (Cornwallis Island, Nunavut, Canada) revisited

Meretta Lake (Resolute Bay, Cornwallis Island, Nunavut, Canada) is a polar lake that has been receiving sewage since 1949 via a series of watercourses and utilidors from the so-called `North Base' of the Canadian Department of Transport. The lake's physical, chemical and biological characteristics were studied between 1968 and 1972 as part of the Char Lake Project, which was a component of the International Biological Programme (IBP). This was the first detailed study of high arctic lake eutrophication. However, since the time of the IBP, use of the North Base has declined markedly. Between 1992 and 1999, we re-sampled Meretta Lake for a suite of limnological variables, and compared our findings to those gathered during IBP. Our data indicate that, although Meretta Lake was still more eutrophic in the 1990s than near-by, undisturbed high arctic lakes, it presently has much lower nutrient concentrations and other trophic state variables than it did during IBP. These concentrations continued to decline in the 1990s, coincident with further decreases in usage of the base. Our most recent data indicate that Meretta Lake nutrient levels are now near `natural' background levels. Furthermore, phytoplankton are characterised by higher abundances of cryptophytes than those recorded in the early 1970s, again indicating less eutrophic conditions. Diatom-based, paleolimnological techniques recorded marked species assemblage shifts coincident with the eutrophication from the North Base. However, similar to the phytoplankton data, species assemblage changes were different from those recorded following eutrophication in more temperate regions, with periphytic diatoms overwhelmingly dominating the assemblages.

Pristine Lake Saint-François, St. Lawrence River: Hydrodynamic Simulation and Cumulative Impact

Lake Saint-François is a fluvial lake of the St. Lawrence system which is used for hydropower production and commercial navigation. For 150 years, it was dredged and dammed regularly without any impact analysis being made. The cumulative impact of dredging and damming on large rivers such as the St. Lawrence is an issue with only qualitative answers. Bidimensional hydrodynamics was used to simulate ancient flow conditions and to produce quantitative descriptors. Two Numerical Field Models (NFM) were prepared, one representing present state geometry, which contains 300,000 sounding points, and the other representing pristine state, based on 1900 and 1870 measurements and containing 70,000 soundings. These two NFMs were compared, showing important changes in the morphology of the lake. The NFMs were then used for bidimensional hydrodynamic simulations of both actual and pristine states for 3 different discharges: 5,000 m 3/s, 7,500 m 3/s, and 10,000 m 3/s. Results highlight the cumulative physical transformation of the system. Hydrodynamic simulations and velocity differences show an increase of velocities over shoals for discharge under 8,800 m 3/s, and a decrease of velocities in deeper water for the same range of discharge. Dredging and straightening around Cornwall Island resulted in changes from 64% to 71% of the total river flow passing through the south channel while the flow in the north channel decreased from 36% to 29%. These hydrodynamic transformations had a definitive impact on sedimentation and most probably on aquatic plant distribution.

Insolitignum n.gen. and Palaeoephippium Goodbody 1986 (Radiolaria) from the Lower Silurian of the Cape Phillips Formation, Arctic Canada

Radiolaria of the family Palaeoscenidiidae were recovered from two bedded-limestone and two limestone-concretion samples from the upper Llandovery of the Cape Phillips Formation, Cornwallis Island, Arctic Canada. The new genus Insolitignum is defined by two apical rays, three basal rays, and a principal ray in an intermediate position. The principal ray distinguishes this genus from Palaeoephippium. Insolitignum dissimile, the type species of the new genus, was previously placed in Palaeoephippium. New species described here are Insolitignum peranima, Insolitignum vivanima, and Palaeoephippium adraini.