Environmental Concerns and International Migration

1996 ◽  
Vol 30 (1) ◽  
pp. 105-131 ◽  
Author(s):  
Graeme Hugo
Keyword(s):  
Environmental Factors ◽  
International Migration ◽  
Environmental Changes ◽  
Environmental Concerns ◽  
Independent Variable

This article focuses on international migration occurring as a result of environmental changes and processes. It briefly reviews attempts to conceptualize environment-related migration and then considers the extent to which environmental factors have been and may be significant in initiating migration. Following is an examination of migration as an independent variable in the migration-environment relationship. Finally, ethical and policy dimensions are addressed.

scholarly journals Distribution Patterns of Odonate Assemblages in Relation to Environmental Variables in Streams of South Korea

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 152 ◽  
Author(s):  
Da-Yeong Lee ◽  
Dae-Seong Lee ◽  
Mi-Jung Bae ◽  
Soon-Jin Hwang ◽  
Seong-Yu Noh ◽  
...  
Keyword(s):  
Land Use ◽  
Ecosystem Services ◽  
Environmental Factors ◽  
South Korea ◽  
Habitat Heterogeneity ◽  
Environmental Variables ◽  
Environmental Changes ◽  
Distribution Patterns ◽  
Self Organizing Map ◽  
Factors Affecting

Odonata species are sensitive to environmental changes, particularly those caused by humans, and provide valuable ecosystem services as intermediate predators in food webs. We aimed: (i) to investigate the distribution patterns of Odonata in streams on a nationwide scale across South Korea; (ii) to evaluate the relationships between the distribution patterns of odonates and their environmental conditions; and (iii) to identify indicator species and the most significant environmental factors affecting their distributions. Samples were collected from 965 sampling sites in streams across South Korea. We also measured 34 environmental variables grouped into six categories: geography, meteorology, land use, substrate composition, hydrology, and physicochemistry. A total of 83 taxa belonging to 10 families of Odonata were recorded in the dataset. Among them, eight species displayed high abundances and incidences. Self-organizing map (SOM) classified sampling sites into seven clusters (A–G) which could be divided into two distinct groups (A–C and D–G) according to the similarities of their odonate assemblages. Clusters A–C were characterized by members of the suborder Anisoptera, whereas clusters D–G were characterized by the suborder Zygoptera. Non-metric multidimensional scaling (NMDS) identified forest (%), altitude, and cobble (%) in substrata as the most influential environmental factors determining odonate assemblage compositions. Our results emphasize the importance of habitat heterogeneity by demonstrating its effect on odonate assemblages.

scholarly journals Graptolite dynamics in Silurian and Devonian time

1987 ◽  
Vol 35 ◽  
pp. 149-159
Author(s):  
T. N. Koren'
Keyword(s):  
Environmental Factors ◽  
Sea Level ◽  
Comparative Studies ◽  
Climate Changes ◽  
Environmental Changes ◽  
Time Intervals ◽  
Early Devonian ◽  
Carbonate Sedimentation ◽  
Reference Sections ◽  
Devonian Age

On the basis of biostratigraphic data known at present some preliminary attempts are made to evaluate graptolite dynamics, that is changes in graptolite diversity in time and space within pelagic fades of Si­lurian and Early Devonian age. For the comparative studies of diversity fluctuations versus some major environmental changes a standard graptolite zonation is used. Several critical and more or less well stu­died stratigraphical intervals are chosen; among them the Ordovician/Silurian, Sheinwoodian/Gorstian and Gorstian/Ludfordian boundary beds. For each level the most complete reference sections are analy­zed. Special attention is given to the graptolite extinction, specification and radiation events within these time intervals. They might have been partly connected with or influenced by the environmental factors as a result of eustatic sea-level and climate changes, alteration of anoxic conditions, migration of carbonate sedimentation in pelagic direction, and other globally detectable events. The graptolite evolution during the time of monograptid existence can be subdivided into three phases using the comparison of the ampli­tude of the extinction-origination events and repeatability of the synphasic cycles.

scholarly journals Key Environmental Factors Controlling Planktonic Foraminiferal and Pteropod Community’s Response to Late Quaternary Hydroclimate Changes in the South Aegean Sea (Eastern Mediterranean)

2020 ◽  
Vol 8 (9) ◽  
pp. 709
Author(s):  
Christina Giamali ◽  
George Kontakiotis ◽  
Efterpi Koskeridou ◽  
Chryssanthi Ioakim ◽  
Assimina Antonarakou
Keyword(s):  
Environmental Factors ◽  
Environmental Changes ◽  
Late Quaternary ◽  
Eastern Mediterranean ◽  
Planktonic Foraminifera ◽  
Explanatory Power ◽  
Principal Component ◽  
Aegean Sea ◽  
Late Glacial ◽  
The South

A multidisciplinary study was conducted in order to investigate the environmental factors affecting the planktonic foraminiferal and pteropod communities of the south Aegean Sea. Aspects of the Late Quaternary paleoceanographic evolution were revealed by means of quantitative analyses of planktonic foraminiferal and pteropod assemblages (including multivariate statistical approach; principal component analysis (PCA)), the oxygen (δ18O) and carbon (δ13C) isotopic composition of planktonic foraminifera and related paleoceanographic (planktonic paleoclimatic curve (PPC), productivity (E-index), stratification (S-index), seasonality) indices, extracted by the gravity core KIM-2A derived from the submarine area between Kimolos and Sifnos islands. Focusing on the last ~21 calibrated thousands of years before present (ka BP), cold and eutrophicated conditions were identified during the Late Glacial period (21.1–15.7 ka BP) and were followed by warmer and wetter conditions during the deglaciation phase. The beginning of the Holocene was marked by a climatic amelioration and increased seasonality. The more pronounced environmental changes were identified during the deposition of the sapropel sublayers S1a (9.4–7.7 ka BP) and S1b (6.9–6.4 ka BP), with extremely warm and stratified conditions. Pteropod fauna during the sapropel deposition were recorded for the first time in the south Aegean Sea, suggesting arid conditions towards the end of S1a. Besides sea surface temperature (SST), which shows the highest explanatory power for the distribution of the analyzed fauna, water column stratification, primary productivity, and seasonality also control their communities during the Late Quaternary.

scholarly journals The Effect of Host, Habitat and Fasting Time on the Gut Microbiota of Amphibian

2021 ◽  
Author(s):  
Qing Tong ◽  
Li-yong Cui ◽  
Zong-fu Hu ◽  
Xiao-peng Du ◽  
Hong-bin Wang
Keyword(s):  
Environmental Factors ◽  
Gut Microbiota ◽  
Environmental Changes ◽  
Early Stage ◽  
Information Criterion ◽  
Shannon Index ◽  
Lifestyle Changes ◽  
Fasting Time ◽  
The Impact ◽  
Late Stages

Abstract Wild animals entering captivity experience radical lifestyle changes resulting in microbiota alterations, in large part due to differences in diet. However, little is known about how external environmental factors influences the gut microbiota and the interaction of the environment-host-microbe interactions in host fasting. The gut microbiota in the early stage (amA and dyA groups) and late stage of hibernation in Rana amurensis and R. dybowskii of entering captivity (amL and dyL groups) and wild environments (amS and dyS groups) was determined, and the effects of host, environmental factors and fasting time on the gut microbiota were investigated via high-throughput Illumina sequencing. The Shannon index differed significantly between the amL and dyL groups and between the amA and amS groups. The PD index differed significantly between the dyL and dyS groups. Eight core OTUs were widely distributed between species, habitats and fasting times and were dominant in abundance. Captive and wild environments, host species, and fasting time significantly affected the composition and structure of the gut microbiota. Akaike information criterion (AIC)-based model results suggested that the environment and host were the variables that needed to be included in redundancy analysis (RDA) to explain the variance in taxa. The pairwise distances between the early and late stages of hibernation of were greater in R. amurensis and R. dybowskii entering captivity than in wild. The average of OTUs shared by early and late stages of hibernation of captive frogs was significantly lower than the average of wild frogs. These results can reveal the impact of environmental changes on the gut microbiota, thereby revealing the important interactions between environment-host-microbes, and helping to protect vertebrate hosts.

scholarly journals Machine learning-assisted neurotoxicity prediction in human midbrain organoids

2019 ◽  
Author(s):  
Anna S. Monzel ◽  
Kathrin Hemmer ◽  
Tony Kaoma Mukendi ◽  
Philippe Lucarelli ◽  
Isabel Rosety ◽  
...  
Keyword(s):  
Machine Learning ◽  
Environmental Factors ◽  
Neurodegenerative Diseases ◽  
Cellular Response ◽  
Environmental Changes ◽  
Complex Structure ◽  
Cellular Tissue ◽  
Imaging Data ◽  
Induced Pluripotent

AbstractA major challenge in the field of neurodegenerative diseases is the poor translation of pre-clinical models to clinical applications. The human brain is an immensely complex structure, which makes it difficult to recapitulate its development, function and disorders. In the recent years, brain organoids derived from human induced pluripotent stem cells have risen as novel tools to study neurodegenerative diseases such as Parkinson’s disease (PD). PD is a multifactorial disorder, with aging, genetics and environmental factors as key etiological elements. The majority of the PD cases are idiopathic and proposed to result from a complex interaction between genetic predisposition and environmental exposure. Consequently, the identification of potentially disease causing environmental factors is of critical importance. Organoids, as complex multi-cellular tissue proxies, are an ideal tool to study cellular response to environmental changes. However, with increasing complexity of the system, usage of quantitative tools becomes challenging. This led us to develop an automated high-content image analysis pipeline for image-based cell profiling in the organoid system. Here, we introduce a midbrain organoid system that recapitulates features of neurotoxin-induced PD, representing a platform for machine-learning-assisted prediction of neurotoxicity in high-content imaging data. This model is a valuable tool for advanced in vitro PD modeling and for the screening of putative neurotoxic compounds.

scholarly journals Diversity and distribution of heterotrophic flagellates in seawater of the Powell Basin, Antarctic Peninsula

2021 ◽  
Vol 40 ◽  
Author(s):  
Zhiyi Chen ◽  
Jianfeng He ◽  
Shunan Cao ◽  
Zhibo Lu ◽  
Musheng Lan ◽  
...  
Keyword(s):  
Community Structure ◽  
Environmental Factors ◽  
Antarctic Peninsula ◽  
Environmental Changes ◽  
Bacterial Biomass ◽  
Heterotrophic Nanoflagellates ◽  
Heterotrophic Flagellates ◽  
Polar Regions ◽  
Biological Interactions ◽  
Essential Components

Heterotrophic flagellates are essential components of the marine microbial food web. However, how the changes in flagellate populations reflect environmental changes in marine ecosystems is still unclear, especially in polar regions. In this study, we used pyrosequencing to examine the community structure of heterotrophic flagellates (HFs) in the Powell Basin’s surface waters of the northern Antarctic Peninsula. OTUs (operational taxonomic units) of different taxa and the correlations between community structure and environmental factors were analysed. Eight taxa of HFs were selected for the principal analysis: Telonemia, Picozoa, Rhizaria, Amoebozoa, Apusomonas, Centrohelida, Choanomonada and marine stramenopiles (MASTs). The HFs were defined as heterotrophic picoflagellates (HPFs; <3 μm) and heterotrophic nanoflagellates (HNFs; >3 μm, <20 μm), which had similar dominant phyla (MASTs and Telonemia). However, their taxonomic composition differed. Environmental factors exerted similar effects on the community structure of both HPFs and HNPs. Compared with the correlation between HPF and environmental factors, the correlation between HNF and environmental factors was stronger. Salinity, bacterial biomass and the biological interactions amongst dominant taxa were the main variables to influence the diversity and community structure of HFs.

scholarly journals Evaluating environmental drivers of spatial variability in free-living nematode assemblages along the Portuguese margin

2017 ◽  
Vol 14 (3) ◽  
pp. 651-669 ◽  
Author(s):  
Lidia Lins ◽  
Frederik Leliaert ◽  
Torben Riehl ◽  
Sofia Pinto Ramalho ◽  
Eliana Alfaro Cordova ◽  
...  
Keyword(s):  
Community Structure ◽  
Environmental Factors ◽  
Food Availability ◽  
Environmental Changes ◽  
Shelf Break ◽  
Environmental Drivers ◽  
Continental Margins ◽  
Sediment Heterogeneity ◽  
Iberian Margin ◽  
Upper Slope

Abstract. Understanding processes responsible for shaping biodiversity patterns on continental margins is an important requirement for comprehending anthropogenic impacts in these environments and further management of biodiversity. Continental margins perform crucial functions linked to key ecological processes which are mainly structured by surface primary productivity and particulate organic matter flux to the seafloor, but also by heterogeneity in seafloor characteristics. However, to what extent these processes control local and regional biodiversity remains unclear. In this study, two isobathic parallel transects located at the shelf break (300–400 m) and upper slope (1000 m) of the western Iberian margin were used to test how food input and sediment heterogeneity affect nematode diversity independently from the spatial factors geographical distance and water depth. We also examined the potential role of connectedness between both depth transects through molecular phylogenetic analyses. Regional generic diversity and turnover were investigated at three levels: within a station, between stations from the same depth transect, and between transects. High variability in food availability and high sediment heterogeneity at the shelf-break transect were directly linked to high diversity within stations and higher variation in community structure across stations compared to the upper slope transect. Contrastingly, environmental factors (food availability and sediment) did not vary significantly between stations located at the upper slope, and this lack of differences were also reflected in a low community turnover between these deeper stations. Finally, differences in nematode communities between both transects were more pronounced than differences within each of the isobathic transects, but these changes were paralleled by the previously mentioned environmental changes. These results suggest that changes in community structure are mainly dictated by environmental factors rather than spatial differences at the western Iberian margin. Furthermore, phylogenetic relationships revealed no evidence for depth-endemic lineages, indicating regular species interchanges across different depths.

scholarly journals Unraveling the effects of environmental drivers and spatial structure on benthic species distribution patterns in Eurasian-Arctic seas (Barents, Kara and Laptev Seas)

Polar Biology ◽  
2020 ◽  
Vol 43 (11) ◽  
pp. 1693-1705
Author(s):  
Miriam L. S. Hansen ◽  
Dieter Piepenburg ◽  
Dmitrii Pantiukhin ◽  
Casper Kraan
Keyword(s):  
Environmental Factors ◽  
Spatial Structure ◽  
Large Scale ◽  
Environmental Changes ◽  
Spatial Scales ◽  
Distribution Patterns ◽  
Environmental Drivers ◽  
Arctic Seas ◽  
Faunal Distribution ◽  
The Impact

Abstract In times of accelerating climate change, species are challenged to respond to rapidly shifting environmental settings. Yet, faunal distribution and composition are still scarcely known for remote and little explored seas, where observations are limited in number and mostly refer to local scales. Here, we present the first comprehensive study on Eurasian-Arctic macrobenthos that aims to unravel the relative influence of distinct spatial scales and environmental factors in determining their large-scale distribution and composition patterns. To consider the spatial structure of benthic distribution patterns in response to environmental forcing, we applied Moran’s eigenvector mapping (MEM) on a large dataset of 341 samples from the Barents, Kara and Laptev Seas taken between 1991 and 2014, with a total of 403 macrobenthic taxa (species or genera) that were present in ≥ 10 samples. MEM analysis revealed three spatial scales describing patterns within or beyond single seas (broad: ≥ 400 km, meso: 100–400 km, and small: ≤ 100 km). Each scale is associated with a characteristic benthic fauna and environmental drivers (broad: apparent oxygen utilization and phosphate, meso: distance-to-shoreline and temperature, small: organic carbon flux and distance-to-shoreline). Our results suggest that different environmental factors determine the variation of Eurasian-Arctic benthic community composition within the spatial scales considered and highlight the importance of considering the diverse spatial structure of species communities in marine ecosystems. This multiple-scale approach facilitates an enhanced understanding of the impact of climate-driven environmental changes that is necessary for developing appropriate management strategies for the conservation and sustainable utilization of Arctic marine systems.

Revisiting Bedrock Values: The Stability and Predictive Power of the Society Works Best Index

2017 ◽  
Vol 46 (2) ◽  
pp. 308-335 ◽  
Author(s):  
Michelle Torres ◽  
Steven S. Smith
Keyword(s):  
Measurement Error ◽  
Panel Data ◽  
Environmental Factors ◽  
Predictive Power ◽  
Environmental Changes ◽  
Political Attitudes ◽  
Political Interest ◽  
Empirical Application ◽  
The Stability

In their 2011 piece, Smith et al. argue that there is a set of fundamental or bedrock values that predict ideology and that are strongly influenced by genetics. These values are considered universal, stable, and less susceptible to environmental changes. Smith et al. propose a scale to measure such values: the Society Works Best Index (SWBI). This is an important contribution, but the SWBI requires further evaluation. Using novel panel data, we evaluate the measure, improve on the empirical application with a national panel, and suggest improvements in the scale. We find that the SWBI is no more stable than other measures of ideology and that the observed changes are attributed to measurement error and environmental factors. Furthermore, like many other political attitudes, its predictive power is mediated by levels of political interest.

Different but the Same

2016 ◽  
Vol 666 (1) ◽  
pp. 203-218 ◽  
Author(s):  
Katharine M. Donato ◽  
Amanda R. Carrico ◽  
Blake Sisk ◽  
Bhumika Piya
Keyword(s):  
Labor Market ◽  
International Migration ◽  
Legal Status ◽  
Environmental Changes ◽  
Economic Outcomes ◽  
Event History ◽  
Substantial Variation ◽  
Bank Account ◽  
Social Contacts ◽  
Unique Dataset

This article builds on prior studies that document how legal status stratifies society, specifically in outcomes related to international migration. Here, we study such outcomes in Bangladesh, a low-lying nation that has experienced dramatic environmental changes in recent decades and high rates of out-migration. We do event history analyses of a new and unique dataset that includes information from approximately eighteen hundred households in nine villages to investigate whether and how legal status differentiates out-migration from Bangladesh. We find substantial variation in legal status among the women and men who make an initial international trip and that unauthorized migration affects other labor market and economic outcomes: it reduces the number of hours that migrants work in destination countries, lowers the odds that migrants pay taxes or open a bank account, and increases the odds that migrants use social contacts to find jobs.

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