Total photosynthetic biomass record between 9400 and 2200 BP and its link to temperature changes at a High Arctic site near Ny-Ålesund, Svalbard

Arctic woollybear caterpillars, Gynaephora groenlandica, had the capacity to rapidly and dramatically increase respiration rates up to fourfold within 12–24 h of feeding and exhibited similar decreases in respiration of 60–85 % in as little as 12 h of starvation. At the peak of their feeding season, the respiration rates of caterpillars also increased significantly with temperature from 0.5 to 22 degreesC for both fed and starved caterpillars (Q10=1-5). Indicative of diapause, late season caterpillars had depressed respiration rates which were less sensitive to temperature changes (Q10 approximately 1.5), while respiration rates for caterpillars that had spun hibernacula were even lower. G. groenlandica did not appear to demonstrate metabolic cold adaptation compared with other temperate lepidopteran larvae. The seasonal capacity to adjust metabolic rate rapidly in response to food consumption and temperature (which can be elevated by basking) may promote the efficient acquisition of energy during the brief (1 month) summer growing and feeding season, while conserving energy by entering diapause when conditions are less favorable. These adaptations, along with their long 15–20 year life cycle and the retention of freeze tolerance year-round, promote the survival of G. groenlandica in this harsh polar environment.

Download Full-text

Reconstruction of past temperatures for Arctic glaciers subjected to intense subsurface melting

Annals of Glaciology ◽

10.3189/172756405781813654 ◽

2005 ◽

Vol 40 ◽

pp. 61-66 ◽

Cited By ~ 4

Author(s):

Oleg V. Nagornov ◽

Yuri V. Konovalov ◽

Vladimir Tchijov

Keyword(s):

High Arctic ◽

Temperature Fields ◽

Model Parameters ◽

Temperature Changes ◽

Ice Caps ◽

Air Temperatures ◽

Subsurface Layers ◽

Climate Signals ◽

Arctic Temperature ◽

Severnaya Zemlya

AbstractMany glaciers are subject to melting due to high summer air temperatures. Here, the presence of meltwater in the subsurface layers of the glacier bulk, and its subsequent percolation and refreezing are implemented in the calibration of a paleothermometer. Accounting for the melt feature index and the measured oxygen-isotope ratio allows for calibration of the paleothermometer and comparison of different climatic proxies. The results of reconstructions agree with previous reconstructions at the depth of attenuation of the seasonal climate signals, which supports the validity of the paleothermometer calibration. The sensitivity of the reconstruction to variations of the model parameters was also studied. It was found that most likely snow–firn sequence and temperature fields were subjected to significant change due to current warming. Temperature changes in the snow–firn thickness of Akademii Nauk (Severnaya Zemlya, Russian High Arctic) and Austfonna (Svalbard) ice caps exceed by ∼6˚C the average Arctic temperature anomalies for the last 150 years. The reconstruction of the past surface temperatures and the parameters of the subsurface heat source due to refreezing of meltwater lead to the conclusion that meltwater spreads inside two to four annual layers for Akademii Nauk and Austfonna ice caps, respectively.

Download Full-text

DIEL PERIODICITIES OF EMERGENCE OF SOME HIGH ARCTIC CHIRONOMIDAE (DIPTERA)

The Canadian Entomologist ◽

10.4039/ent104903-6 ◽

1972 ◽

Vol 104 (6) ◽

pp. 903-916 ◽

Cited By ~ 29

Author(s):

H. V. Danks ◽

D. R. Oliver

Keyword(s):

Light Intensity ◽

Water Temperature ◽

Temperature Fluctuation ◽

High Arctic ◽

Middle Part ◽

Physical Factors ◽

Short Term ◽

Temperature Changes ◽

Emergence Pattern ◽

Critical Thresholds

AbstractThe diel periodicities of emergence of seven species of chironomids from two ponds in the Hazen Camp area (81°49′ N., 71°18′ W.) are considered in relation to physical factors. Emergence of all species is greatest during the middle part of the day: an increase in water temperature induces emergence and a decrease inhibits it, whereas changes in light intensity, ultraviolet radiation, sunshine, and wind appear to have no effect on the diel emergence pattern. In a shallow pond, males emerge slightly earlier in the day than females in some species. In the same pond also, emergence, particularly of females, is sometimes distinctly bimodal. In a deeper tarn where the diel temperature fluctuation is very small there is a single peak, which is less pronounced than in the shallow pond.That temperature controls the periodicity of emergence implies that short-term temperature changes which may inhibit adult activity are of great importance in the high arctic. At these latitudes, changes in light intensity evidently do not reliably indicate to the emerging organisms temperatures which fluctuate near critical thresholds for activity.

Download Full-text

Cryo-TEM of amphiphilic polymer and amphiphile/polymer solutions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150216 ◽

1993 ◽

Vol 51 ◽

pp. 876-877

Author(s):

Yeshayahu Talmon

Keyword(s):

Microstructural Characterization ◽

Building Blocks ◽

Quantitative Information ◽

Physical Models ◽

Specimen Preparation ◽

Time Resolved ◽

Temperature Changes ◽

Temperature And Humidity ◽

Microstructured Fluids ◽

Air Streams

To achieve complete microstructural characterization of self-aggregating systems, one needs direct images in addition to quantitative information from non-imaging, e.g., scattering or Theological measurements, techniques. Cryo-TEM enables us to image fluid microstructures at better than one nanometer resolution, with minimal specimen preparation artifacts. Direct images are used to determine the “building blocks” of the fluid microstructure; these are used to build reliable physical models with which quantitative information from techniques such as small-angle x-ray or neutron scattering can be analyzed.To prepare vitrified specimens of microstructured fluids, we have developed the Controlled Environment Vitrification System (CEVS), that enables us to prepare samples under controlled temperature and humidity conditions, thus minimizing microstructural rearrangement due to volatile evaporation or temperature changes. The CEVS may be used to trigger on-the-grid processes to induce formation of new phases, or to study intermediate, transient structures during change of phase (“time-resolved cryo-TEM”). Recently we have developed a new CEVS, where temperature and humidity are controlled by continuous flow of a mixture of humidified and dry air streams.

Download Full-text

Application of pyrometer and standard sample to determine surface temperature of studied materials

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2019-12-9-13 ◽

2019 ◽

pp. 9-13

Author(s):

V.Ya. Mendeleyev ◽

V.A. Petrov ◽

A.V. Yashin ◽

A.I. Vangonen ◽

O.K. Taganov

Keyword(s):

Composite Material ◽

Surface Temperature ◽

Relative Error ◽

Wavelength Range ◽

Standard Sample ◽

A Priori ◽

Temperature Changes ◽

Surface Temperatures ◽

Relative Errors ◽

Normal Emissivity

Determining the surface temperature of materials with unknown emissivity is studied. A method for determining the surface temperature using a standard sample of average spectral normal emissivity in the wavelength range of 1,65–1,80 μm and an industrially produced Metis M322 pyrometer operating in the same wavelength range. The surface temperature of studied samples of the composite material and platinum was determined experimentally from the temperature of a standard sample located on the studied surfaces. The relative error in determining the surface temperature of the studied materials, introduced by the proposed method, was calculated taking into account the temperatures of the platinum and the composite material, determined from the temperature of the standard sample located on the studied surfaces, and from the temperature of the studied surfaces in the absence of the standard sample. The relative errors thus obtained did not exceed 1,7 % for the composite material and 0,5% for the platinum at surface temperatures of about 973 K. It was also found that: the inaccuracy of a priori data on the emissivity of the standard sample in the range (–0,01; 0,01) relative to the average emissivity increases the relative error in determining the temperature of the composite material by 0,68 %, and the installation of a standard sample on the studied materials leads to temperature changes on the periphery of the surface not exceeding 0,47 % for composite material and 0,05 % for platinum.

Download Full-text

Late Holocene precipitation and temperature changes in Northern Europe linked with North Atlantic forcing

Climate Research ◽

10.3354/cr01331 ◽

2015 ◽

Vol 66 (1) ◽

pp. 37-48 ◽

Cited By ~ 9

Author(s):

TP Luoto ◽

L Nevalainen

Keyword(s):

North Atlantic ◽

Late Holocene ◽

Northern Europe ◽

Temperature Changes ◽

Precipitation And Temperature

Download Full-text

Ecological niche modelling of cold-water corals in the Southern Ocean (N Antarctic), present distribution and future projections due to temperature changes

Marine Ecology Progress Series ◽

10.3354/meps13085 ◽

2019 ◽

Vol 628 ◽

pp. 73-93

Author(s):

S Chaabani ◽

PJ López-González ◽

P Casado-Amezua ◽

H Pehlke ◽

L Weber ◽

...

Keyword(s):

Southern Ocean ◽

Ecological Niche ◽

Cold Water ◽

Ecological Niche Modelling ◽

Niche Modelling ◽

Future Projections ◽

Temperature Changes ◽

Present Distribution

Download Full-text

Summer phytoplankton of the northern Barents Sea (75–80º N)

Hydrosphere Еcology (Экология гидросферы) ◽

10.33624/2587-9367-2019-2(4)-8-19 ◽

2019 ◽

pp. 8-19

Author(s):

Larisa A. Pautova ◽

Vladimir A. Silkin ◽

Marina D. Kravchishina ◽

Valeriy G. Yakubenko ◽

Anna L. Chultsova

Keyword(s):

Barents Sea ◽

Weighted Average ◽

Arctic Basin ◽

High Arctic ◽

Alexandrium Tamarense ◽

Warm Water ◽

The Arctic ◽

Absolute Maximum ◽

Deep Trench ◽

Maximum Biomass

The structure of the summer planktonic communities of the Northern part of the Barents sea in the first half of August 2017 were studied. In the sea-ice melting area, the average phytoplankton biomass producing upper 50-meter layer of water reached values levels of eutrophic waters (up to 2.1 g/m3). Phytoplankton was presented by diatoms of the genera Thalassiosira and Eucampia. Maximum biomass recorded at depths of 22–52 m, the absolute maximum biomass community (5,0 g/m3) marked on the horizon of 45 m (station 5558), located at the outlet of the deep trench Franz Victoria near the West coast of the archipelago Franz Josef Land. In ice-free waters, phytoplankton abundance was low, and the weighted average biomass (8.0 mg/m3 – 123.1 mg/m3) corresponded to oligotrophic waters and lower mesotrophic waters. In the upper layers of the water population abundance was dominated by small flagellates and picoplankton from, biomass – Arctic dinoflagellates (Gymnodinium spp.) and cold Atlantic complexes (Gyrodinium lachryma, Alexandrium tamarense, Dinophysis norvegica). The proportion of Atlantic species in phytoplankton reached 75%. The representatives of warm-water Atlantic complex (Emiliania huxleyi, Rhizosolenia hebetata f. semispina, Ceratium horridum) were recorded up to 80º N, as indicators of the penetration of warm Atlantic waters into the Arctic basin. The presence of oceanic Atlantic species as warm-water and cold systems in the high Arctic indicates the strengthening of processes of “atlantificacion” in the region.

Download Full-text