scholarly journals Essai: Is Arctic Palynology a “Blunt Instrument”?

2007 ◽  
Vol 60 (2) ◽  
pp. 95-102 ◽  
Author(s):  
Konrad Gajewski
Keyword(s):  
Environmental Change ◽  
Spatial Resolution ◽  
The Arctic ◽  
Arctic Ecosystems ◽  
Temporal And Spatial ◽  
Pollen Analyses ◽  
The Way

AbstractFor nearly forty years, palynologists and other scientists studying the Quaternary have claimed that palynology, when applied in the Arctic, is a “blunt instrument” for analysing environmental change in this region. In this essay, the author explains why this expression should be laid to rest. Limits to palynological resolution are spatial, temporal and taxonomic. These are discussed and examples are shown where both the temporal and spatial resolution of pollen analyses is far higher than previously thought possible. The supposed “bluntness” of Arctic palynology is due to the way this tool has been applied in Arctic environments rather than inherent limits of palynology in Arctic ecosystems.

3. Arctic ecosystems

2021 ◽  
pp. 39-62
Author(s):  
Klaus Dodds ◽  
Jamie Woodward
Keyword(s):  
Environmental Change ◽  
Soil Depth ◽  
Nutrient Supply ◽  
The Arctic ◽  
High Latitudes ◽  
Arctic Ecosystems ◽  
Arctic Vegetation ◽  
Animal Populations ◽  
Key Characteristics ◽  
The Arctic Ocean

‘Arctic ecosystems’ highlights the treeless landscapes that fringe the Arctic Ocean, in which the diversity of plants is low, nutrient supply is limited, and soil depth is constrained by permafrost. The aim is to capture some of the key characteristics of the Arctic biome in the past and present. How do ecosystems function in the northern high latitudes? How have they responded to the recent environmental change? Arctic vegetation is grouped into twenty-one provinces based on various characteristics including relative uniformity of species and number of endemics. High fluctuation in animal populations is a key feature of the Arctic biome.

scholarly journals Dispersal limitation and climate-related environmental gradients structure microcrustacean composition in freshwater lakes, Ellesmere Island, Canada

2008 ◽  
Vol 65 (9) ◽  
pp. 1905-1918 ◽  
Author(s):  
Angela L. Strecker ◽  
Rebecca Milne ◽  
Shelley E. Arnott
Keyword(s):  
Species Richness ◽  
Environmental Change ◽  
Community Composition ◽  
Environmental Gradients ◽  
Negative Relationship ◽  
Ellesmere Island ◽  
Arctic Lakes ◽  
The Arctic ◽  
Arctic Ecosystems ◽  
Daphnia Middendorffiana

Dramatic environmental change is expected in the Arctic, yet little is known about the occurrence and community composition of microcrustaceans in Arctic lakes and how this will be influenced by future environmental change. We sampled and calculated relative abundances of microcrustacean species in 54 lakes on Ellesmere Island, Canada. New species records on Ellesmere Island included Daphnia umbra , Tachidius discipes , and Artemeopsis stefanssoni . Daphnia middendorffiana/tenebrosa was the most common taxon and often dominated microcrustacean assemblages, likely a result of its pigmentation, which offers resistance to ultraviolet radiation. Species richness was positively associated with nutrients, dissolved organic carbon (DOC), temperature, calcium, and conductivity and negatively affected by elevation. In contrast to most findings in temperate systems, we detected a negative relationship between species richness and surface area. Community composition was influenced by DOC, nutrients, and elevation but was also related to spatial variables, suggesting that spatial gradients in environmental conditions and dispersal are important drivers of differences among sites. Arctic ecosystems are expected to change rapidly in the coming years because of climate change and ozone thinning, and we expect that associated changes in DOC, temperature, and nutrients will affect microcrustacean species richness and distribution throughout the landscape.

scholarly journals Automatic High-Accuracy Sea Ice Mapping in the Arctic Using MODIS Data

2021 ◽  
Vol 13 (4) ◽  
pp. 550
Author(s):  
Liyuan Jiang ◽  
Yong Ma ◽  
Fu Chen ◽  
Jianbo Liu ◽  
Wutao Yao ◽  
...  
Keyword(s):  
Sea Ice ◽  
Spatial Resolution ◽  
Feature Fusion ◽  
Learning Algorithm ◽  
High Accuracy ◽  
The Arctic ◽  
Polar Regions ◽  
Generation Model ◽  
Clear Sky ◽  
Temporal And Spatial

The sea ice cover is changing rapidly in polar regions, and sea ice products with high temporal and spatial resolution are of great importance in studying global climate change and navigation. In this paper, an ice map generation model based on Moderate-Resolution Imaging Spectroradiometer (MODIS) reflectance bands is constructed to obtain sea ice data with a high temporal and spatial resolution. By constructing a training sample library and using a multi-feature fusion machine learning algorithm for model classification, the high-accuracy recognition of ice and cloud regions is achieved. The first product provided by this algorithm is a near real-time single-scene sea ice presence map. Compared with the photo-interpreted ground truth, the verification shows that the algorithm can obtain a higher recognition accuracy for ice, clouds, and water, and the accuracy exceeds 98%. The second product is a daily and weekly clear sky map, which provides synthetic ice presence maps for one day or seven consecutive days. A filtering method based on cloud motion is used to make the product more accurate. The third product is a weekly fusion of clear sky optical images. In a comparison with the Advanced Microwave Scanning Radiometer 2 (AMSR2) sea ice concentration products performed in August 2019 and September 2020, these composite images showed spatial consistency over time, suggesting that they can be used in many scientific and practical applications in the future.

Memories for the Return? Remembering the Nakba by the First Generation of Palestinian Refugees in Syria

2017 ◽  
Vol 16 (2) ◽  
pp. 177-192 ◽  
Author(s):  
Anaheed Al-Hardan
Keyword(s):  
First Generation ◽  
Palestinian Refugees ◽  
Oslo Accords ◽  
Right Of Return ◽  
Palestinian Refugee ◽  
Temporal And Spatial ◽  
The Right ◽  
Political Realities ◽  
The Way

The 1948 Nakba has, in light of the 1993 Oslo Accords and Palestinian refugee activists' mobilisation around the right of return, taken on a new-found centrality and importance in Palestinian refugee communities. Closely-related to this, members of the ‘Generation of Palestine’, the only individuals who can recollect Nakba memories, have come to be seen as the guardians of memories that are eventually to reclaim the homeland. These historical, social and political realities are deeply rooted in the ways in which the few remaining members of the generation of Palestine recollect 1948. Moreover, as members of communities that were destroyed in Palestine, and whose common and temporal and spatial frameworks were non-linearly constituted anew in Syria, one of the multiples meanings of the Nakba today can be found in the way the refugee communities perceive and define this generation.

Humans and the Environment

2013 ◽  
Keyword(s):  
Spatial Scales ◽  
Empirical Studies ◽  
Human Action ◽  
Cultural Practice ◽  
Environmental Archaeology ◽  
Archaeological Data ◽  
Temporal And Spatial ◽  
Global And Local ◽  
The Relationship ◽  
The Way

The environment has always been a central concept for archaeologists and, although it has been conceived in many ways, its role in archaeological explanation has fluctuated from a mere backdrop to human action, to a primary factor in the understanding of society and social change. Archaeology also has a unique position as its base of interest places it temporally between geological and ethnographic timescales, spatially between global and local dimensions, and epistemologically between empirical studies of environmental change and more heuristic studies of cultural practice. Drawing on data from across the globe at a variety of temporal and spatial scales, this volume resituates the way in which archaeologists use and apply the concept of the environment. Each chapter critically explores the potential for archaeological data and practice to contribute to modern environmental issues, including problems of climate change and environmental degradation. Overall the volume covers four basic themes: archaeological approaches to the way in which both scientists and locals conceive of the relationship between humans and their environment, applied environmental archaeology, the archaeology of disaster, and new interdisciplinary directions.The volume will be of interest to students and established archaeologists, as well as practitioners from a range of applied disciplines.

scholarly journals Semi-automated classification of colonial Microcystis by FlowCAM imaging flow cytometry in mesocosm experiment reveals high heterogeneity during seasonal bloom

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yersultan Mirasbekov ◽  
Adina Zhumakhanova ◽  
Almira Zhantuyakova ◽  
Kuanysh Sarkytbayev ◽  
Dmitry V. Malashenkov ◽  
...  
Keyword(s):  
Machine Learning ◽  
Flow Cytometry ◽  
Spatial Resolution ◽  
Mesocosm Experiment ◽  
Imaging Flow Cytometry ◽  
Leibler Divergence ◽  
Temporal And Spatial ◽  
High Level ◽  
Training Sets

AbstractA machine learning approach was employed to detect and quantify Microcystis colonial morphospecies using FlowCAM-based imaging flow cytometry. The system was trained and tested using samples from a long-term mesocosm experiment (LMWE, Central Jutland, Denmark). The statistical validation of the classification approaches was performed using Hellinger distances, Bray–Curtis dissimilarity, and Kullback–Leibler divergence. The semi-automatic classification based on well-balanced training sets from Microcystis seasonal bloom provided a high level of intergeneric accuracy (96–100%) but relatively low intrageneric accuracy (67–78%). Our results provide a proof-of-concept of how machine learning approaches can be applied to analyze the colonial microalgae. This approach allowed to evaluate Microcystis seasonal bloom in individual mesocosms with high level of temporal and spatial resolution. The observation that some Microcystis morphotypes completely disappeared and re-appeared along the mesocosm experiment timeline supports the hypothesis of the main transition pathways of colonial Microcystis morphoforms. We demonstrated that significant changes in the training sets with colonial images required for accurate classification of Microcystis spp. from time points differed by only two weeks due to Microcystis high phenotypic heterogeneity during the bloom. We conclude that automatic methods not only allow a performance level of human taxonomist, and thus be a valuable time-saving tool in the routine-like identification of colonial phytoplankton taxa, but also can be applied to increase temporal and spatial resolution of the study.

scholarly journals Variability in nitrogen-derived trophic levels of Arctic marine biota

Polar Biology ◽  
2020 ◽  
Author(s):  
Renske P. J. Hoondert ◽  
Nico W. van den Brink ◽  
Martine J. van den Heuvel-Greve ◽  
Ad M. J. Ragas ◽  
A. Jan Hendriks
Keyword(s):  
Stable Isotopes ◽  
Enrichment Factors ◽  
Trophic Levels ◽  
The Arctic ◽  
Marine Biota ◽  
Arctic Ecosystems ◽  
Arctic Species ◽  
Single Region ◽  
Benthic Food ◽  
Species Specific

AbstractStable isotopes are often used to provide an indication of the trophic level (TL) of species. TLs may be derived by using food-web-specific enrichment factors in combination with a representative baseline species. It is challenging to sample stable isotopes for all species, regions and seasons in Arctic ecosystems, e.g. because of practical constraints. Species-specific TLs derived from a single region may be used as a proxy for TLs for the Arctic as a whole. However, its suitability is hampered by incomplete knowledge on the variation in TLs. We quantified variation in TLs of Arctic species by collating data on stable isotopes across the Arctic, including corresponding fractionation factors and baseline species. These were used to generate TL distributions for species in both pelagic and benthic food webs for four Arctic areas, which were then used to determine intra-sample, intra-study, intra-region and inter-region variation in TLs. Considerable variation in TLs of species between areas was observed. This is likely due to differences in parameter choice in estimating TLs (e.g. choice of baseline species) and seasonal, temporal and spatial influences. TLs between regions were higher than the variance observed within regions, studies or samples. This implies that TLs derived within one region may not be suitable as a proxy for the Arctic as a whole. The TL distributions derived in this study may be useful in bioaccumulation and climate change studies, as these provide insight in the variability of trophic levels of Arctic species.

scholarly journals Societal implications of a changing Arctic Ocean

AMBIO ◽  
2021 ◽  
Author(s):  
Henry P. Huntington ◽  
Andrey Zagorsky ◽  
Bjørn P. Kaltenborn ◽  
Hyoung Chul Shin ◽  
Jackie Dawson ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Indigenous Peoples ◽  
Global Climate ◽  
Rapid Change ◽  
The Arctic ◽  
Cultural Continuity ◽  
Societal Implications ◽  
Arctic Ecosystems ◽  
The Many

AbstractThe Arctic Ocean is undergoing rapid change: sea ice is being lost, waters are warming, coastlines are eroding, species are moving into new areas, and more. This paper explores the many ways that a changing Arctic Ocean affects societies in the Arctic and around the world. In the Arctic, Indigenous Peoples are again seeing their food security threatened and cultural continuity in danger of disruption. Resource development is increasing as is interest in tourism and possibilities for trans-Arctic maritime trade, creating new opportunities and also new stresses. Beyond the Arctic, changes in sea ice affect mid-latitude weather, and Arctic economic opportunities may re-shape commodities and transportation markets. Rising interest in the Arctic is also raising geopolitical tensions about the region. What happens next depends in large part on the choices made within and beyond the Arctic concerning global climate change and industrial policies and Arctic ecosystems and cultures.

Potential of Arabic documentary sources for reconstructing past climate in the western Mediterranean region from AD 680 to 1815

The Holocene ◽  
2021 ◽  
pp. 095968362110332
Author(s):  
Yassin Meklach ◽  
Chantal Camenisch ◽  
Abderrahmane Merzouki ◽  
Ricardo Garcia Herrera
Keyword(s):  
Spatial Resolution ◽  
Mediterranean Region ◽  
Climate Extremes ◽  
Western Mediterranean ◽  
Historical Documents ◽  
Atmospheric Conditions ◽  
Documentary Sources ◽  
Drought Conditions ◽  
Temporal And Spatial ◽  
Climate Proxies

Archival records and historical documents offer direct observation of weather and atmospheric conditions and have the highest temporal and spatial resolution, and precise dating, of the available climate proxies. They also provide information about variables such as temperature, precipitation and climate extremes, as well as floods, droughts and storms. The present work studied Arab-Islamic documentary sources covering the western Mediterranean region (documents written by Arab-Islamic historians that narrate social, political and religious history) available for the period AD 680–1815. They mostly provide information on hydrometeorological events. In Iberia the most intense droughts were reported during AD 747–753, AD 814–822, AD 846–847, AD 867–874 and AD 914–915 and in the Maghreb AD 867–873, AD 898–915, AD 1104–1147, AD 1280–1340 and AD 1720–1815 had prevalent drought conditions. Intense rain episodes are also reported.

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