scholarly journals Stable isotope signatures of Holocene syngenetic permafrost trace seabird presence in the Thule District (NW Greenland)

2019 ◽  
Vol 16 (21) ◽  
pp. 4261-4275
Author(s):  
Sebastian Wetterich ◽  
Thomas A. Davidson ◽  
Anatoly Bobrov ◽  
Thomas Opel ◽  
Torben Windirsch ◽  
...  
Keyword(s):  
Organic Matter ◽  
Cold Season ◽  
Accumulation Rates ◽  
Climate Trends ◽  
High Accumulation ◽  
Opposite Pattern ◽  
Little Auk ◽  
Peat Accumulation ◽  
The North ◽  
Ice Wedge

Abstract. Holocene permafrost from ice wedge polygons in the vicinity of large seabird breeding colonies in the Thule District, NW Greenland, was drilled to explore the relation between permafrost aggradation and seabird presence. The latter is reliant on the presence of the North Water Polynya (NOW) in the northern Baffin Bay. The onset of peat accumulation associated with the arrival of little auks (Alle alle) in a breeding colony at Annikitisoq, north of Cape York, is radiocarbon-dated to 4400 cal BP. A thick-billed murre (Uria lomvia) colony on Appat (Saunders Island) in the mouth of the Wolstenholme Fjord started 5650 cal BP. Both species provide marine-derived nutrients (MDNs) that fertilize vegetation and promote peat growth. The geochemical signature of organic matter left by the birds is traceable in the frozen Holocene peat. The peat accumulation rates at both sites are highest after the onset, decrease over time, and were about 2-times faster at the little auk site than at the thick-billed murre site. High accumulation rates induce shorter periods of organic matter (OM) decomposition before it enters the perennially frozen state. This is seen in comparably high C∕N ratios and less depleted δ13C, pointing to a lower degree of OM decomposition at the little auk site, while the opposite pattern can be discerned at the thick-billed murre site. Peat accumulation rates correspond to δ15N trends, where decreasing accumulation led to increasing depletion in δ15N as seen in the little-auk-related data. In contrast, the more decomposed OM of the thick-billed murre site shows almost stable δ15N. Late Holocene wedge ice fed by cold season precipitation was studied at the little auk site and provides the first stable-water isotopic record from Greenland with mean δ18O of -18.0±0.8 ‰, mean δD of -136.2±5.7 ‰, mean d excess of 7.7±0.7 ‰, and a δ18O-δD slope of 7.27, which is close to those of the modern Thule meteoric water line. The syngenetic ice wedge polygon development is mirrored in testacean records of the little auk site and delineates polygon low-center, dry-out, and polygon-high-center stages. The syngenetic permafrost formation directly depending on peat growth (controlled by bird activity) falls within the period of neoglacial cooling and the establishment of the NOW, thus indirectly following the Holocene climate trends.

scholarly journals Stable isotope signatures of Holocene syngenetic permafrost trace seabird presence in the Thule District (NW Greenland)

2019 ◽  
Author(s):  
Sebastian Wetterich ◽  
Thomas A. Davidson ◽  
Anatoly Bobrov ◽  
Thomas Opel ◽  
Torben Windirsch ◽  
...  
Keyword(s):  
Organic Matter ◽  
Cold Season ◽  
Accumulation Rates ◽  
Climate Trends ◽  
High Accumulation ◽  
Opposite Pattern ◽  
Little Auk ◽  
Peat Accumulation ◽  
The North ◽  
Ice Wedge

Abstract. Holocene permafrost from ice wedge polygons in the vicinity of large seabird breeding colonies in the Thule District, NW Greenland, was drilled to explore the relation between permafrost aggradation and seabird presence. The latter is reliant on the presence of the North Water (NOW) polynya in the northern Baffin Bay. The onset of peat accumulation associated with the arrival of little auks (Alle alle) in a breeding colony at Annikitisoq north of Cape York is radiocarbon-dated to 4400 cal yr BP. A thick-billed murre (Uria lomvia) colony on Appat (Saunders Ø) in the mouth of the Wolstenholme Fjord started 5650 cal yr BP. Both species provide marine-derived nutrients (MDNs) that fertilise vegetation and promote peat growth. The geochemical signature of organic matter left by the birds is traceable in the frozen Holocene peat. The peat accumulation rates at both sites are highest after the onset and decrease over time and were about two-times faster at the little auk site than at the thick-billed murre site. High accumulation rates induce shorter periods of organic matter (OM) decomposition before it enters the perennially frozen state. This is seen in comparably high C / N and less depleted δ13C, pointing to a lower degree of OM decomposition at the little auk site, while the opposite pattern can be discerned at the thick-billed murre site. Peat accumulation rates correspond to δ15N trends, where decreasing accumulation led to increasing depletion in δ15N as seen in the little-auk related data. In contrast, the more decomposed OM of the thick-billed murre site shows almost stable δ15N. Late Holocene wedge ice fed by cold season precipitation was studied at the little auk site and provides the first such stable-water isotopic records from Greenland with mean δ18O of −18.0 ± 0.8 ‰, mean δD of −136.2 ± 5.7 ‰, mean d excess of 7.7 ± 0.7 ‰, and a δ18O-δD slope of 7.27, which is close to those of the modern Thule Meteoric Water Line. The syngenetic ice wedge polygon development is mirrored in testacean records of the little auk site and delineates polygon low-centre, dry-out and polygon-high-centre stages. The syngenetic permafrost formation directly depending on peat growth (controlled by bird activity) falls within the period of Neoglacial cooling and the establishment of the NOW polynya, thus indirectly follows the Holocene climate trends.

scholarly journals Eclipse Ice Core Accumulation and Stable Isotope Variability as an Indicator of North Pacific Climate

2012 ◽  
Vol 25 (18) ◽  
pp. 6426-6440 ◽  
Author(s):  
Eric P. Kelsey ◽  
Cameron P. Wake ◽  
Kaplan Yalcin ◽  
Karl Kreutz
Keyword(s):  
Stable Isotope ◽  
North Pacific ◽  
Geopotential Height ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Cold Season ◽  
High Accumulation ◽  
The North ◽  
The Individual

Abstract The high accumulation rate and negligible amount of melt at Eclipse Icefield (3017 m) in the Saint Elias Range of Yukon, Canada, allows for the preservation of a high-resolution isotopic and glaciochemical records valuable for reconstruction of climatic variables. Each of the three Eclipse ice cores have a well-constrained depth–age scale with dozens of reference horizons over the twentieth century that permits an exceptional level of confidence in the results of the current calibration exercise. Stacked time series of accumulation and stable isotopes were divided into cold and warm seasons and seasons of extreme high and extreme low accumulation and stable isotope values (eight groups). For each group, season-averaged composites of 500-hPa geopotential height grids, and the individual seasons that constitute them, were analyzed to elucidate common anomalous flow patterns. This analysis shows that the most fractionated isotopes and lowest accumulation cold seasons reflect a more zonal height pattern in the North Pacific associated with negative Pacific–North American (PNA) and Pacific decadal oscillation (PDO) indices. Conversely, the least fractionated isotopes and highest accumulation cold seasons are associated with a positive PNA pattern. Although only a maximum of approximately 20% of the total number of accumulation and stable isotope seasons exhibit a relatively consistent relationship with 500-hPa geopotential height patterns, these results support the hypothesis that the most extreme accumulation and extreme isotope cold-season values in the Saint Elias Mountains are related to consistent atmospheric circulation and oceanic sea surface temperature patterns.

scholarly journals Vulnerability of the North Water ecosystem to climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sofia Ribeiro ◽  
Audrey Limoges ◽  
Guillaume Massé ◽  
Kasper L. Johansen ◽  
William Colgan ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Late Holocene ◽  
Sediment Cores ◽  
Arctic Ecosystems ◽  
Little Auk ◽  
The North ◽  
Water Ecosystem ◽  
North Water

AbstractHigh Arctic ecosystems and Indigenous livelihoods are tightly linked and exposed to climate change, yet assessing their sensitivity requires a long-term perspective. Here, we assess the vulnerability of the North Water polynya, a unique seaice ecosystem that sustains the world’s northernmost Inuit communities and several keystone Arctic species. We reconstruct mid-to-late Holocene changes in sea ice, marine primary production, and little auk colony dynamics through multi-proxy analysis of marine and lake sediment cores. Our results suggest a productive ecosystem by 4400–4200 cal yrs b2k coincident with the arrival of the first humans in Greenland. Climate forcing during the late Holocene, leading to periods of polynya instability and marine productivity decline, is strikingly coeval with the human abandonment of Greenland from c. 2200–1200 cal yrs b2k. Our long-term perspective highlights the future decline of the North Water ecosystem, due to climate warming and changing sea-ice conditions, as an important climate change risk.

Sinking organic matter spreads the nitrogen isotope signal of pelagic denitrification in the North Pacific

2009 ◽  
Vol 36 (8) ◽  
Author(s):  
Daniel M. Sigman ◽  
Peter J. DiFiore ◽  
Mathis P. Hain ◽  
Curtis Deutsch ◽  
David M. Karl
Keyword(s):  
Organic Matter ◽  
North Pacific ◽  
Nitrogen Isotope ◽  
The North ◽  
The North Pacific

scholarly journals Diet composition and feeding habits of the eyespot skate, Atlantoraja cyclophora (Elasmobranchii: Arhynchobatidae), off Uruguay and northern Argentina

2016 ◽  
Vol 14 (3) ◽  
Author(s):  
Santiago A. Barbini ◽  
Luis O. Lucifora
Keyword(s):  
Body Size ◽  
Diet Composition ◽  
Prey Size ◽  
Prey Availability ◽  
Feeding Habits ◽  
Warm Season ◽  
Cold Season ◽  
The North ◽  
Multiple Hypothesis ◽  
Modelling Approach

ABSTRACT The eyespot skate, Atlantoraja cyclophora, is an endemic species from the southwestern Atlantic, occurring from Rio de Janeiro, Brazil, to northern Patagonia, Argentina. The feeding habits of this species, from off Uruguay and north Argentina, were evaluated using a multiple hypothesis modelling approach. In general, the diet was composed mainly of decapod crustaceans, followed by teleost fishes. Molluscs, mysidaceans, amphipods, isopods, lancelets and elasmobranchs were consumed in lower proportion. The consumption of shrimps drecreased with increasing body size of A. cyclophora. On the other hand, the consumption of teleosts increased with body size. Mature individuals preyed more heavily on crabs than immature individuals. Teleosts were consumed more in the south region (34º - 38ºS) and crabs in the north region (38º - 41ºS). Shrimps were eaten more in the warm season than in the cold season. Prey size increased with increasing body size of A. cyclophora , but large individuals also consumed small teleosts and crabs. Atlantoraja cyclophora has demersal-benthic feeding habits, shifts its diet with increasing body size and in response to seasonal and regional changes in prey availability and distribution.

scholarly journals SEDIMENTOLOGICAL AND GEOCHEMICAL ANALYSIS OF MIOCENE DEPOSITS IN MOSCHOPOTAMOS AREA, IN THE WESTERN PART OF AXIOS-THERMAIKOS BASIN, NW GREECE

2017 ◽  
Vol 50 (1) ◽  
pp. 374
Author(s):  
V. Savva ◽  
P. Tserolas ◽  
A. Maravelis ◽  
N. Bourli ◽  
A. Zelilidis
Keyword(s):  
Organic Matter ◽  
Organic Content ◽  
Sieve Analysis ◽  
Organic Carbon Content ◽  
Geochemical Analysis ◽  
Aegean Area ◽  
Sedimentary Characteristics ◽  
The North ◽  
Caco3 Content ◽  
North Aegean

A total of 27 samples of the Moschopotamos area lignite-bearing strata were studied in regard of their geochemical and sedimentary characteristics. Organic content and calcium carbonate evaluation, sieve analysis and micropaleontological observations were used and combined to investigate the paleoenvironment and the depositional conditions of the study area. TOC analysis showed that organic matter values range from 0.07% up to 13.42% with an average of ~3.26 %. The high average of organic carbon content indicates a promising basis for the sediments’ source rock potential, inquiring further and thorough examination. CaCO3 measurements present a range between 4% and 23%. A comparison between TOC-CaCO3 content throughout the stratigraphic column presented certain synchronous and inverse trends, due to alterations of the depositional conditions. This study provides new insights for the understanding of the broader Axios-Thermaikos basin, and depositional conditions in the North Aegean area.

scholarly journals CHROMOSOME STUDIES IN WILD POPULATIONS OF DROSOPHILA MELANOGASTER. II. RELATIONSHIP OF INVERSION FREQUENCIES TO LATITUDE, SEASON, WING-LOADING AND FLIGHT ACTIVITY

Genetics ◽  
1980 ◽  
Vol 95 (1) ◽  
pp. 211-223
Author(s):  
Harrison D Stalker
Keyword(s):  
Drosophila Melanogaster ◽  
Warm Season ◽  
Cold Season ◽  
South Texas ◽  
Temperature Adaptation ◽  
Wing Loading ◽  
Ambient Temperatures ◽  
The North ◽  
Wing Load ◽  
Relationship Of

ABSTRACT In the midwestern and eastern U.S. populations of Drosophila melanogaster, the Standard gene arrangements show higher frequencies in the north than in the south. In a Missouri population, and to a lesser extent in a south Texas population, the frequencies of Standard chromosomes regularly rise during the cold season and drop during the warm season, thus paralleling the north-south frequency differences. In the Missouri population in 1976 and 1978, wild males were tested far their ability to fly to bait at different ambient temperatures. In both years, males flying in nature in the temperature range of 13° to 15° showed significantly higher frequencies of Standard chromosomes than did those flying in the 16° to 28° range. Wild males flying at 13° to 15° also have different tharax/wing proportions and significantly lower wingloading indices than do those flying at 16° to 28°. Moreover, wild flies homozygous Standard in 2R and/or 3R have significantly lower wing-loading indices than flies carrying inversions in these arms. Thus, wild flies with high frequencies of Standard chromosommes are karyotypically northern, are selectively favored during the cold season, have a relatively low wing-load and are most capable of flying at critically low ambient temperatures.—In summary, in Missouri, presence or absence of the common cosmopolitan inversions is an important factor in low temperature adaptation, and at least part of the adaptive mechanism involves control of thorax/wing proportions and thus control of wing-loading.

scholarly journals Transformation of Atlantic Water in the north-eastern Barents Sea in winter

2020 ◽  
Vol 66 (3) ◽  
pp. 246-266
Author(s):  
V. V. Ivanov ◽  
I. E. Frolov ◽  
K. V. Filchuk
Keyword(s):  
Barents Sea ◽  
Cold Season ◽  
Atlantic Water ◽  
High Concentration ◽  
The North ◽  
Driving Mechanisms ◽  
The Barents Sea ◽  
Open Sea ◽  
North Eastern ◽  
Transformation Mechanisms

Hydrographic observations, carried out in March-May, 2019 during “Transarktika-2019” expedition onboard R/V “Akademik Tryoshnikov” allowed studying mechanisms of Atlantic Water (AW) transformation in the Barents Sea. Although this research topic is rather traditional for oceanographic studies, there are still a number of questions, which require clarification. Among these is a deeper understanding of the AW transformation in specific regions in cold season, when the coverage by observations is scarce. In this study we performed temperature and salinity (TS) analysis of conductivity — temperature — depth (CTD) data, collected in the north-eastern “corner” of the Barents Sea — this is the area with difficult access in winter due to high concentration of pack ice. The results allowed identification of areas along the pathways of AW branches, where various types of open sea convection and cascading acted as dominant processes of AW properties change. We distinguish several driving mechanisms controlling modification of the waters of Atlantic origin. An advantage of winter measurements is that the active stage of AW transformation mechanisms is explicitly observed at the consecutive CTD sections.

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