scholarly journals Interactions between climate and landscape drive Holocene ecological change in a High Arctic lake on Somerset Island, Nunavut, Canada

2017 ◽  
Vol 3 (1) ◽  
pp. 17-38 ◽  
Author(s):  
Tara M. Paull ◽  
Sarah A. Finkelstein ◽  
Konrad Gajewski
Keyword(s):  
Environmental History ◽  
Lake Water ◽  
Sediment Accumulation ◽  
Base Cations ◽  
High Arctic ◽  
Ecological Change ◽  
Diatom Assemblages ◽  
Time Period ◽  
Water Ph ◽  
Somerset Island

This study presents a diatom-based analysis of the post-glacial Holocene environmental history at Lake RS29 on Somerset Island in the Canadian High Arctic. Earliest post-glacial diatom assemblages (10 200–10 000 cal yr BP) consisted mainly of small, benthic fragilarioid taxa. Poor diatom preservation in the early Holocene (~10 000–6200 cal yr BP) is associated with warm conditions, as determined by pollen data from the same core and other paleoclimate estimates from the region. Analysis of this and other sites from across the Canadian Arctic suggest that zones of poor diatom preservation or diatom absence in lake sediment records may be associated with warm conditions. After 6200 cal yr BP, acidophilic assemblages consisting of Aulacoseira spp. and a suite of periphytic taxa indicate acidification since the mid-Holocene. During this time period, cooling causing changes in lake ice phenology was likely a major driver of the reconstructed mid-Holocene pH decline. Watershed processes, including reduced fluxes of base cations as the rate of sediment accumulation slowed, may also be contributors to long-term shifts in lake water pH and associated changes in diatom assemblages. The uppermost sediments in the Lake RS29 record were characterized by abrupt declines in Aulacoseira alpigena and increases in benthic diatom taxa Cyclotella sensu lato, suggesting an increase in lake water pH and longer ice-free seasons.

Palaeolimnology of Lake Zeribar, Iran, and its Climatic Implications

2006 ◽  
Vol 66 (3) ◽  
pp. 477-493 ◽  
Author(s):  
Krystyna Wasylikowa ◽  
Andrzej Witkowski ◽  
Adam Walanus ◽  
Andrzej Hutorowicz ◽  
Stefan W. Alexandrowicz ◽  
...  
Keyword(s):  
Water Level ◽  
Lake Water ◽  
Climatic Changes ◽  
Strong Increase ◽  
Diatom Assemblages ◽  
Pronounced Increase ◽  
Lake Water Level ◽  
Water Level Changes ◽  
Time Period ◽  
Distinct Increase

AbstractLake Zeribar sediments covering the time period of the last 25,000 years were examined for the contents of seeds, fruits, Characeae, diatoms, and molluscs. Reconstructions of the variations in the lake water level, salinity, and trophy suggest a sequence of climatic changes. Three pronounced stages of low and varying lake-water level occurred ca. 17,700–15,400, 12,600–12,000, and 10,000–6000 cal yr BP. Some water-level changes were correlated with variations in salinity. The most pronounced increase of salinity occurred 17,700–15,700 and 12,600–12,000 cal yr BP, and less distinct ones occurred about 6400–5900 and 2500 cal yr BP. Diatom assemblages indicated a strong increase of lake trophy ca. 20,200 cal yr BP. Between 6000 and 5000 cal yr BP diatoms characteristic of eutrophy increased in core 63J, and at about 3200 cal yr BP a distinct increase in mesotrophic forms occurred in core 70B. The changes in the occurrence of various organisms indicate increased temperatures about 21,000 cal yr BP, between 15,400 and 12,600, about 12,000, and about 11,700 cal yr BP. The reduced occurrence or disappearance of some of them suggest temperature decreases about 17,700–15,400 and 12,600–12,000 cal yr BP.

scholarly journals Contrasting the ecological effects of decreasing ice cover versus accelerated glacial melt on the High Arctic's largest lake

2020 ◽  
Vol 287 (1929) ◽  
pp. 20201185
Author(s):  
Neal Michelutti ◽  
Marianne S. V. Douglas ◽  
Dermot Antoniades ◽  
Igor Lehnherr ◽  
Vincent L. St. Louis ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Fold Increase ◽  
Mass Gain ◽  
Ecological Change ◽  
Diatom Assemblages ◽  
Lake Ice ◽  
Glacial Meltwater ◽  
Glacial Runoff ◽  
Common Era ◽  
Ecological Functioning

Lake Hazen, the High Arctic's largest lake, has received an approximately 10-fold increase in glacial meltwater since its catchment glaciers shifted from net mass gain to net mass loss in 2007 common era (CE), concurrent with recent warming. Increased glacial meltwater can alter the ecological functioning of recipient aquatic ecosystems via changes to nutrient budgets, turbidity and thermal regimes. Here, we examine a rare set of five high-resolution sediment cores collected in Lake Hazen between 1990 and 2017 CE to investigate the influence of increased glacial meltwater versus alterations to lake ice phenology on ecological change. Subfossil diatom assemblages in all cores show two major shifts over the past approximately 200 years including: (i) a proliferation of pioneering, benthic taxa at approximately 1900 CE from previously depauperate populations; and (ii) a rise in planktonic taxa beginning at approximately 1980 CE to present-day dominance. The topmost intervals from each sequentially collected core provide exact dates and demonstrate that diatom regime shifts occurred decades prior to accelerated glacial inputs. These data show that diatom assemblages in Lake Hazen are responding primarily to intrinsic lake factors linked to decreasing duration of lake ice and snow cover rather than to limnological impacts associated with increased glacial runoff.

scholarly journals Assessing volumetric change distributions and scaling relations of retrogressive thaw slumps across the Arctic

2022 ◽  
Vol 16 (1) ◽  
pp. 1-15
Author(s):  
Philipp Bernhard ◽  
Simon Zwieback ◽  
Nora Bergner ◽  
Irena Hajnsek
Keyword(s):  
Regional Differences ◽  
Scaling Laws ◽  
Remote Sensing Data ◽  
High Arctic ◽  
The Arctic ◽  
Scaling Relations ◽  
Volumetric Change ◽  
Inverse Gamma ◽  
Time Period ◽  
Study Sites

Abstract. Arctic ice-rich permafrost is becoming increasingly vulnerable to terrain-altering thermokarst, and among the most rapid and dramatic of these changes are retrogressive thaw slumps (RTSs). They initiate when ice-rich soils are exposed and thaw, leading to the formation of a steep headwall which retreats during the summer months. The impacts and the distribution and scaling laws governing RTS changes within and between regions are unknown. Using TanDEM-X-derived digital elevation models, we estimated RTS volume and area changes over a 5-year time period from winter 2011/12 to winter 2016/17 and used for the first time probability density functions to describe their distributions. We found that over this time period all 1853 RTSs mobilized a combined volume of 17×106 m3 yr−1, corresponding to a volumetric change density of 77 m3 yr−1 km−2. Our remote sensing data reveal inter-regional differences in mobilized volumes, scaling laws, and terrain controls. The distributions of RTS area and volumetric change rates follow an inverse gamma function with a distinct peak and an exponential decrease for the largest RTSs. We found that the distributions in the high Arctic are shifted towards larger values than at other study sites We observed that the area-to-volume scaling was well described by a power law with an exponent of 1.15 across all study sites; however the individual sites had scaling exponents ranging from 1.05 to 1.37, indicating that regional characteristics need to be taken into account when estimating RTS volumetric changes from area changes. Among the terrain controls on RTS distributions that we examined, which included slope, adjacency to waterbodies, and aspect, the latter showed the greatest but regionally variable association with RTS occurrence. Accounting for the observed regional differences in volumetric change distributions, scaling relations, and terrain controls may enhance the modelling and monitoring of Arctic carbon, nutrient, and sediment cycles.

scholarly journals Multi-year comparisons of ground-based and space-borne Fourier transform spectrometers in the high Arctic between 2006 and 2013

2017 ◽  
Vol 10 (9) ◽  
pp. 3273-3294 ◽  
Author(s):  
Debora Griffin ◽  
Kaley A. Walker ◽  
Stephanie Conway ◽  
Felicia Kolonjari ◽  
Kimberly Strong ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Atmospheric Chemistry ◽  
Trace Gases ◽  
Correlation Coefficients ◽  
High Arctic ◽  
Atmospheric Research ◽  
Time Period ◽  
Experiment Validation ◽  
Mean Differences ◽  
Good Agreement

Abstract. This paper presents 8 years (2006–2013) of measurements obtained from Fourier transform spectrometers (FTSs) in the high Arctic at the Polar Environment Atmospheric Research Laboratory (PEARL; 80.05° N, 86.42° W). These measurements were taken as part of the Canadian Arctic ACE (Atmospheric Chemistry Experiment) validation campaigns that have been carried out since 2004 during the polar sunrise period (from mid-February to mid-April). Each spring, two ground-based FTSs were used to measure total and partial columns of HF, O3, and trace gases that impact O3 depletion, namely, HCl and HNO3. Additionally, some tropospheric greenhouse gases and pollutant species were measured, namely CH4, N2O, CO, and C2H6. During the same time period, the satellite-based ACE-FTS made measurements near Eureka and provided profiles of the same trace gases. Comparisons have been carried out between the measurements from the Portable Atmospheric Research Interferometric Spectrometer for the InfraRed (PARIS-IR) and the co-located high-resolution Bruker 125HR FTS, as well as with the latest version of the ACE-FTS retrievals (v3.5). The total column comparison between the two co-located ground-based FTSs, PARIS-IR and Bruker 125HR, found very good agreement for most of these species (except HF), with differences well below the estimated uncertainties ( ≤ 6  %) and with high correlations (R ≥ 0. 8). Partial columns have been used for the ground-based to space-borne comparison, with coincident measurements selected based on time, distance, and scaled potential vorticity (sPV). The comparisons of the ground-based measurements with ACE-FTS show good agreement in the partial columns for most species within 6  % (except for C2H6 and PARIS-IR HF), which is consistent with the total retrieval uncertainty of the ground-based instruments. The correlation coefficients (R) of the partial column comparisons for all eight species range from approximately 0.75 to 0.95. The comparisons show no notable increases of the mean differences over these 8 years, indicating the consistency of these datasets and suggesting that the space-borne ACE-FTS measurements have been stable over this period. In addition, changes in the amounts of these trace gases during springtime between 2006 and 2013 are presented and discussed. Increased O3 (0. 9  %  yr−1), HCl (1. 7  %  yr−1), HF (3. 8  %  yr−1), CH4 (0.5  % yr−1), and C2H6 (2. 3 % yr−1, 2009–2013) have been found with the PARIS-IR dataset, the longer of the two ground-based records.

The migratory behaviour of narwhals (Monodon monoceros)

2003 ◽  
Vol 81 (8) ◽  
pp. 1298-1305 ◽  
Author(s):  
Mads Peter Heide-Jørgensen ◽  
Rune Dietz ◽  
Kristin L Laidre ◽  
Pierre Richard ◽  
Jack Orr ◽  
...  
Keyword(s):  
Open Water ◽  
High Arctic ◽  
Early Summer ◽  
Canadian High Arctic ◽  
Baffin Bay ◽  
Bay Area ◽  
Monodon Monoceros ◽  
Migratory Routes ◽  
Somerset Island ◽  
Wintering Ground

Sixteen female narwhals (Monodon monoceros) were tracked by satellite in 2000 and 2001 from their summering ground near Somerset Island in the Canadian High Arctic to their wintering ground in central Baffin Bay. The wintering ground location was spatially discrete from another narwhal wintering ground in southern Baffin Bay. Area extent of the summering ground was approximately 9464 km2 and area extent of the wintering ground was 25 846 km2. Two of the narwhals were tracked for more than 12 consecutive months. These whales used three focal areas between their spring and autumn migration: a coastal area in the open-water season in August in the Canadian High Arctic, a wintering area from November through April in the consolidated pack ice of Baffin Bay, and an early summer area in front of the receding fast ice edge in Lancaster Sound. The whales showed remarkable site fidelity to summering grounds and had specific migratory routes that followed sea ice formation and recession.

scholarly journals Pathways for Ecological Change in Canadian High Arctic Wetlands Under Rapid Twentieth Century Warming

2019 ◽  
Vol 46 (9) ◽  
pp. 4726-4737 ◽  
Author(s):  
T. G. Sim ◽  
G. T. Swindles ◽  
P. J. Morris ◽  
M. Gałka ◽  
D. Mullan ◽  
...  
Keyword(s):  
Twentieth Century ◽  
High Arctic ◽  
Ecological Change ◽  
Canadian High Arctic ◽  
Arctic Wetlands

Assessment of Changes in Lake Water Chemistry in Sudbury Area Lakes since Preindustrial Times

1992 ◽  
Vol 49 (S1) ◽  
pp. 8-16 ◽  
Author(s):  
Sushil S. Dixit ◽  
Aruna S. Dixit ◽  
John P. Smol
Keyword(s):  
Lake Water ◽  
Acidic Ph ◽  
Prevailing Wind ◽  
Alkaline Ph ◽  
Sediment Samples ◽  
Ion Concentrations ◽  
The Past ◽  
Lake Water Chemistry ◽  
Water Ph ◽  
Inferred Ph

Surface (recent) and bottom (pre-1880s) sediment samples from each of 72 Sudbury area lakes were analyzed for diatom valves and chrysophyte scales, and using these microfossils, we inferred changes in lake water pH, [Al], [Ni], conductance, and [Ca]. The study shows that extensive acidification has occurred in presently acidic (pH < 6.0) Sudbury lakes. Inferred [Al] has also increased in these lakes. The region also contains a few naturally acidic lakes; however, even these lakes have acidified further since the bottom sediments were deposited. Lakes that have current measured pH between 6.0 and 7.0 have either declined or increased in inferred pH in the past, whereas all lakes that are presently alkaline (pH > 7.0) have become more alkaline. The increase in inferred [Ni] in most of the study lakes indicates that Ni inputs are mainly atmospheric. Our data suggest that, in general, ion concentrations have increased in Sudbury lakes. The extent of acidification or alkalification in Sudbury lakes was primarily a function of proximity of the lakes to the smelters, orientation of prevailing wind patterns, and differences in watershed geology.

Spatial and Temporal Assessment of Titiwangsa Lake Water Quality Using Chemometrics Analysis

2018 ◽  
Vol 7 (3.14) ◽  
pp. 20
Author(s):  
Hafizan Juahir ◽  
Adiana Ghazali ◽  
Azimah Ismail ◽  
Mahadzirah Mohamad ◽  
Firdaus Mohamad Hamzah ◽  
...  
Keyword(s):  
Water Quality ◽  
Lake Water ◽  
Monitoring Program ◽  
Water Quality Monitoring ◽  
Quality Monitoring ◽  
Current Status ◽  
Small Scale ◽  
Lake Water Quality ◽  
Night Time ◽  
Time Period

Titiwangsa Lake is a renowned recreational lake in Kuala Lumpur, Malaysia. The present study was purposely to define the current status of Titiwangsa Lake water quality and propose a water quality monitoring program to conserve and sustain the health of this lake. Samples were collected in January 2017 during the day and night-time periods. Spatial classification using hierarchical agglomerative cluster analysis (HACA) has clustered the sampling stations into low, medium and high contaminated areas. Temporal classification of discriminant analysis (DA) forward stepwise mode has highlighted DO, chlorophyll-a and E-coli are the significant variables. They showed a lower range of data during the day-time period compared to night-time period. DA backward stepwise model showed  significant variables of total suspended solid (TSS) and total phosphate (TP) were higher in concentration during the day-time period as compared to night-time period. The significant of varimax factors (VFs) in the principal component analysis (PCA) might contribute by the landscaping, small-scale domestic wastewater, urban stormwater and land erosion. In a nutshell, based on HACA classification, samples can be collected at only three stations represent each cluster during the next water quality monitoring activities as this could reduce the time and cost of sampling and sample analysis. 

Correlation of surface sediment diatoms with the present lake water pH in 28 Algoma lakes, Ontario, Canada

Hydrobiologia ◽  
1986 ◽  
Vol 131 (2) ◽  
pp. 133-143 ◽  
Author(s):  
Sushil S. Dixit ◽  
Mike D. Dickman
Keyword(s):  
Surface Sediment ◽  
Lake Water ◽  
Water Ph

scholarly journals Transitional occupations of southeastern Somerset Island, Nunavut

2005 ◽  
Vol 27 (1-2) ◽  
pp. 213-238
Author(s):  
Eric Damkjar
Keyword(s):  
High Arctic ◽  
Transitional Period ◽  
Radiocarbon Dates ◽  
Somerset Island ◽  
Architectural Characteristics

Abstract Four transitional period sites on Somerset Island compare closely with High Arctic sites attributed to Independence II. The four sites are situated at elevations between Pre-Dorset and Early Dorset occupations in the same area. The sites are described, with an emphasis on architectural characteristics. Vertical slab midpassage structures are present at all sites along with artifact assemblages containing shallowly side-notched bifaces, "cloven hoof" lance heads, a closed socket harpoon head, burin-like tools, narrow microblades, and needles with gouged eyes. Some sites also have exterior hearths and possible caches. Radiocarbon dates place the occupations within the transitional period (i.e. 800-500 B.C.). As during Independence II, the sites are of various size (three small ones and a large one), and are in association with polynyas.

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