Remains of non-pollen-palynomorphs – tardigrades from Spitsbergen found during pollen analyses

Polar Record ◽  
2016 ◽  
Vol 52 (4) ◽  
pp. 450-463 ◽  
Author(s):  
Vlasta Jankovská ◽  
Milena Roszkowska ◽  
Łukasz Kaczmarek
Keyword(s):  
Environmental Conditions ◽  
Sediment Cores ◽  
Peat Bogs ◽  
Northwestern Part ◽  
Polar Regions ◽  
Native Flora ◽  
The Past ◽  
Analytical Studies ◽  
Pollen Analyses

ABSTRACTPollen- and non-pollen-palynomorphs (NPP) analytical studies of the northwestern part of Spitsbergen were conducted between 1988 and 1991. As well as pollen from local native flora and more dispersed species, some well preserved remains of tardigrada exuvia, buccal tubes and eggs were found. This study reviewed the remains of at least six tardigrade taxa reported:Dactylobiotus ambiguous, Paramacrobiotus richtersigroup,Richtersius coronifer, Macrobiotus hufelandigroup,Macrobiotus peterseniandMinibiotuscf.intermedius, which are reassessed and determined more accurately. These findings provide some new insights into the past environmental conditions and changes for Spitsbergen. Based on the present research it can be concluded that tardigrade remains are frequent NPP elements of pollen analyses from lake, peat bogs and detritus sub-fossil sediment cores, at least in polar regions. It can also be stated that tardigrades can be considered indicators in further palaeontological studies helping to reconstruct past environmental conditions (for example humidity) for some regions. However, the knowledge of tardigrades in these types of analyses is still rather poor.

Developments in sugarcane processing over the past 15 years

2019 ◽  
pp. 451-458
Author(s):  
Peter W. Rein
Keyword(s):  
Environmental Conditions ◽  
Energy Value ◽  
The Past ◽  
Recent Developments ◽  
Technology Of Production ◽  
Sugarcane Processing

Developments in the technology of production of sugar from sugarcane tend to be incremental improvements in an effort to reduce costs and boost revenue. Nonetheless the developments are significant and contribute to sustainable sugarcane enterprises. Some technologies have adapted to changing environmental conditions, and more attention is being given to boosting revenue through associated activities, particularly in enhancing the potential for sugarcane operations to exploit the energy value of sugarcane. This paper outlines recent developments of interest in processing sugarcane.

scholarly journals Quantifying sea surface temperature ranges of the Arabian Sea for the past 20 000 years

2011 ◽  
Vol 7 (4) ◽  
pp. 1337-1349 ◽  
Author(s):  
G. M. Ganssen ◽  
F. J. C. Peeters ◽  
B. Metcalfe ◽  
P. Anand ◽  
S. J. A. Jung ◽  
...  
Keyword(s):  
Arabian Sea ◽  
Isotope Composition ◽  
Planktonic Foraminifera ◽  
Sediment Cores ◽  
Maximum Temperature ◽  
Physical Parameters ◽  
Seasonal Temperature ◽  
Mean Values ◽  
The Past ◽  
Temperature Ranges

Abstract. The oxygen isotopic composition of planktonic foraminifera tests is one of the widest used geochemical tools to reconstruct past changes of physical parameters of the upper ocean. It is common practice to analyze multiple individuals from a mono-specific population and assume that the outcome reflects a mean value of the environmental conditions during calcification of the analyzed individuals. Here we present the oxygen isotope composition of individual specimens of the surface-dwelling species Globigerinoides ruber and Globigerina bulloides from sediment cores in the Western Arabian Sea off Somalia, inferred as indicators of past seasonal ranges in temperature. Combining the δ18O measurements of individual specimens to obtain temperature ranges with Mg/Ca based mean calcification temperatures allows us to reconstruct temperature extrema. Our results indicate that over the past 20 kyr the seasonal temperature range has fluctuated from its present value of 16 °C to mean values of 13 °C and 11 °C for the Holocene and LGM, respectively. The data for the LGM suggest that the maximum temperature was lower, whilst minimum temperature remained approximately constant. The rather minor variability in lowest summer temperatures during the LGM suggests roughly constant summer monsoon intensity, while upwelling-induced productivity was lowered.

scholarly journals Dayside and nightside contributions to the cross polar cap potential: placing an upper limit on a viscous-like interaction

2004 ◽  
Vol 22 (10) ◽  
pp. 3771-3777 ◽  
Author(s):  
S. E. Milan
Keyword(s):  
Magnetic Flux ◽  
Polar Regions ◽  
Polar Cap ◽  
Average Decrease ◽  
The Past ◽  
Viscous Interaction ◽  
The North ◽  
Upper Limit ◽  
The Cross ◽  
Cross Polar Cap Potential

Abstract. Observations of changes in size of the ionospheric polar cap allow the dayside and nightside reconnection rates to be quantified. From these it is straightforward to estimate the rate of antisunward transport of magnetic flux across the polar regions, quantified by the cross polar cap potential ΦPC. When correlated with upstream measurements of the north-south component of the IMF, ΦPC is found to increase for more negative Bz, as expected. However, we also find that ΦPC does not, on average, decrease to zero, even for strongly northward IMF. In the past this has been interpreted as evidence for a viscous interaction between the magnetosheath flow and the outer boundaries of the magnetosphere. In contrast, we show that this is the consequence of flows excited by tail reconnection, which is inherently uncorrelated with IMF Bz.

scholarly journals Pre-akinete formation in Zygnema sp. from polar habitats is associated with metabolite re-arrangement

2020 ◽  
Vol 71 (11) ◽  
pp. 3314-3322 ◽  
Author(s):  
Erwann Arc ◽  
Martina Pichrtová ◽  
Ilse Kranner ◽  
Andreas Holzinger
Keyword(s):  
Environmental Conditions ◽  
Morphological Changes ◽  
Tca Cycle ◽  
Survival Strategies ◽  
Polar Regions ◽  
Akinete Formation ◽  
Metabolite Profiles ◽  
Dividing Cells ◽  
Storage Products ◽  
Chloroplast Morphology

Abstract In streptophytic green algae in the genus Zygnema, pre-akinete formation is considered a key survival strategy under extreme environmental conditions in alpine and polar regions. The transition from young, dividing cells to pre-akinetes is associated with morphological changes and the accumulation of storage products. Understanding the underlying metabolic changes could provide insights into survival strategies in polar habitats. Here, GC-MS-based metabolite profiling was used to study the metabolic signature associated with pre-akinete formation in Zygnema sp. from polar regions under laboratory conditions, induced by water and nutrient depletion, or collected in the field. Light microscopy and TEM revealed drastic changes in chloroplast morphology and ultrastructure, degradation of starch grains, and accumulation of lipid bodies in pre-akinetes. Accordingly, the metabolite profiles upon pre-akinete formation reflected a gradual shift in metabolic activity. Compared with young cells, pre-akinetes showed an overall reduction in primary metabolites such as amino acids and intermediates of the tricarboxylic acid (TCA) cycle, consistent with a lower metabolic turnover, while they accumulated lipids and oligosaccharides. Overall, the transition to the pre-akinete stage involves re-allocation of photosynthetically fixed energy into storage instead of growth, supporting survival of extreme environmental conditions.

Antarctic meteorites

1989 ◽  
Vol 1 (1) ◽  
pp. 3-14 ◽  
Author(s):  
A.L. Graham ◽  
John O. Annexstad
Keyword(s):  
Environmental Conditions ◽  
Ice Sheets ◽  
Unknown Number ◽  
The Past ◽  
Lunar Material ◽  
The Earth ◽  
Extraterrestrial Material

Antarctica is currently the most productive region of the Earth for the recovery of meteorites and over 9800 specimens have been found there, most of these since 1969. This material consists of meteoritic fragments representing a much smaller, but unknown, number of distinct meteorites. The particular climatic and environmental conditions of Antarctica result in the recovery of a much larger fraction of the extraterrestrial material that falls to Earth than would be the case in other regions. Remarkable concentrations of meteorites are found in some ‘blue ice’ areas resulting from the movement and ablation of the ice. Most meteorites are believed to have been derived from asteroids less then 200 km in diameter. The discovery in Antarctica of meteorites of lunar material proved that other sources are possible. Indeed two meteorites from Antarctica may have come from the planet Mars. Antarctic meteorites have much older terrestrial ages than non-Antarctic specimens and may be used to obtain information on the movement of the ice sheets in the past.

scholarly journals A Worm's World: Ecological Flexibility Pays Off for Free-Living Nematodes in Sediments and Soils

BioScience ◽  
2019 ◽  
Vol 69 (11) ◽  
pp. 867-876 ◽  
Author(s):  
Michaela Schratzberger ◽  
Martijn Holterman ◽  
Dick van Oevelen ◽  
Johannes Helder
Keyword(s):  
Environmental Conditions ◽  
Food Sources ◽  
Polar Regions ◽  
Soil Processes ◽  
Free Living ◽  
Ecological Flexibility ◽  
Ecological Success ◽  
The Tropics ◽  
Animal Communities ◽  
The Impact

Abstract Free-living nematodes, an ancient animal phylum of unsegmented microscopic roundworms, have successfully adapted to nearly every ecosystem on Earth: from marine and freshwater to land, from the polar regions to the tropics, and from the mountains to the ocean depths. They are globally the most abundant animals in sediments and soils. In the present article, we identify the factors that collectively explain the successful ecological proliferation of free-living nematodes and demonstrate the impact they have on vital sediment and soil processes. The ecological success of nematodes is strongly linked to their ability to feed on various food sources that are present in both sediments and soils, and to proliferate rapidly and survive in contrasting environmental conditions. The adaptations, roles, and behaviors of free-living nematodes have important implications for the resilience of sediments and soils, and for emergent animal communities responding to human alterations to ecosystems worldwide.

scholarly journals Forest carbon allocation modelling under climate change

2019 ◽  
Vol 39 (12) ◽  
pp. 1937-1960 ◽  
Author(s):  
Katarína Merganičová ◽  
Ján Merganič ◽  
Aleksi Lehtonen ◽  
Giorgio Vacchiano ◽  
Maša Zorana Ostrogović Sever ◽  
...  
Keyword(s):  
Climate Change ◽  
Environmental Conditions ◽  
Carbon Allocation ◽  
Hybrid Approach ◽  
Ecosystem Dynamics ◽  
Nonstructural Carbohydrates ◽  
The Past ◽  
Process Understanding ◽  
Vegetation Models ◽  
The Impact

Abstract Carbon allocation plays a key role in ecosystem dynamics and plant adaptation to changing environmental conditions. Hence, proper description of this process in vegetation models is crucial for the simulations of the impact of climate change on carbon cycling in forests. Here we review how carbon allocation modelling is currently implemented in 31 contrasting models to identify the main gaps compared with our theoretical and empirical understanding of carbon allocation. A hybrid approach based on combining several principles and/or types of carbon allocation modelling prevailed in the examined models, while physiologically more sophisticated approaches were used less often than empirical ones. The analysis revealed that, although the number of carbon allocation studies over the past 10 years has substantially increased, some background processes are still insufficiently understood and some issues in models are frequently poorly represented, oversimplified or even omitted. Hence, current challenges for carbon allocation modelling in forest ecosystems are (i) to overcome remaining limits in process understanding, particularly regarding the impact of disturbances on carbon allocation, accumulation and utilization of nonstructural carbohydrates, and carbon use by symbionts, and (ii) to implement existing knowledge of carbon allocation into defence, regeneration and improved resource uptake in order to better account for changing environmental conditions.

scholarly journals Glacier and ocean variability in Ata Sund, west Greenland, since 1400 CE

The Holocene ◽  
2020 ◽  
Vol 30 (12) ◽  
pp. 1681-1693
Author(s):  
Fanny Ekblom Johansson ◽  
David J Wangner ◽  
Camilla S Andresen ◽  
Jostein Bakke ◽  
Eivind Nagel Støren ◽  
...  
Keyword(s):  
Large Scale ◽  
Bottom Water ◽  
Sediment Cores ◽  
Ice Age ◽  
Bottom Water Temperature ◽  
Ocean Variability ◽  
The Past ◽  
Period 2 ◽  
Climate Cooling ◽  
Tomography Scan

To improve knowledge of marine-terminating glaciers in western Greenland, marine sediment cores from the Ata Sund fjord system, hosting two outlet glaciers, Eqip Sermia and Kangilerngata Sermia, were investigated. The main objective was to reconstruct glacial activity and paleoceanographic conditions during the past 600 years. Ice-rafted debris (IRD) was quantified by wet-sieving sediment samples and by using a computed tomography scan. Variability in relative bottom water temperatures in the fjord was reconstructed using foraminiferal analysis. On the basis of this, three periods of distinct glacial regimes were identified: Period 1 (1380–1810 CE), which covers the culmination of the Little Ice Age (LIA) and is interpreted as having advanced glaciers with high IRD content. Period 2 (1810–1920 CE), the end of the LIA, which was characterised by a lowering of the glaciers’ calving flux in response to climate cooling. During Period 3 (1920–2014 CE), both glaciers retreated substantially to their present-day extent. The bottom water temperature started to decrease just before Period 2 and remained relatively low until just before the end of Period 3. This is interpreted as a local response to increased glacial meltwater input. Our study was compared with a study in Disko Bay, nearby Jakobshavn Glacier and the result shows that both of these Greenlandic marine-terminating glaciers are responding to large-scale climate change. However, the specific imprint on the glaciers and the different fjord waters in front of them result in contrasting glacial responses and sediment archives in their respective fjords.

Forest stability during the early and late Holocene in the igapó floodplains of the Rio Negro, northwestern Brazil

2017 ◽  
Vol 89 (1) ◽  
pp. 75-89 ◽  
Author(s):  
Paula A. Rodríguez-Zorro ◽  
Bruno Turcq ◽  
Renato C. Cordeiro ◽  
Luciane S. Moreira ◽  
Renata L. Costa ◽  
...  
Keyword(s):  
Late Holocene ◽  
Amazon Basin ◽  
Vegetation History ◽  
Sediment Cores ◽  
Northwestern Part ◽  
Human Disturbances ◽  
River Dynamics ◽  
Rio Negro ◽  
Igapó Forest ◽  
Forest Stability

AbstractLocated at the northwestern part of the Amazon basin, Rio Negro is the largest black-water river in the world and is one of the poorest studied regions of the Amazon lowlands. In the middle-upper part of the Rio Negro were retrieved sediment cores form Lake Acarabixi, which were analyzed using pollen, spores, charcoal, and geochemistry. The aim of this study was to detect the influences from humans and river dynamics on the vegetation history in the region. Two main periods of vegetation and river dynamics were detected. From 10,840 to 8240 cal yr BP, the river had a direct influence into the lake. The lake had a regional input of charcoal particles, which reflected the effect of the dry Holocene period in the basin. Furthermore, highland taxa such asHedyosmumandMyrsinewere found at that time along with igapó forest species that are characteristic to tolerate extended flooding likeEschweilera,Macrolobium, Myrtaceae,Swartzia, andAstrocaryum. During the late Holocene (1600 to 650 cal yr BP), more lacustrine phases were observed. There were no drastic changes in vegetation but the presence of pioneer species likeVismiaandCecropia, along with the signal of fires, which pointed to human disturbances.

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