Morphological variation in genetically divergent populations of the common whelk, Buccinum undatum (Gastropoda: Buccinidae), across the North Atlantic

2019 ◽  
Vol 128 (1) ◽  
pp. 93-106 ◽  
Author(s):  
Hildur Magnúsdóttir ◽  
Snæbjörn Pálsson ◽  
Kristen Marie Westfall ◽  
Zophonías O Jónsson ◽  
Erla Björk Örnólfsdóttir
Keyword(s):  
North Atlantic ◽  
Morphological Variation ◽  
Isolation By Distance ◽  
Shell Morphology ◽  
Buccinum Undatum ◽  
The North ◽  
The Common ◽  
The North Atlantic ◽  
Eastern North Atlantic ◽  
The Impact

Abstract The variation in shelled marine gastropod morphology across small spatial scales can reflect restricted population connectivity, resulting in evolution or plastic responses to environmental heterogeneity. The common whelk, Buccinum undatum, is a subtidal gastropod, ubiquitous in the North Atlantic, that exhibits considerable spatial variation in shell morphology and colour. Given that species delimitation in shelled marine gastropods is often based on shell characteristics, such morphological variation can lead to taxonomic confusion. Phylogeographical analysis based on mitochondrial DNA and microsatellites suggested cryptic species composed of Western and Eastern North Atlantic common whelk populations, the separation of which dates to the onset of the Pleistocene glaciation ~2.1 Mya. Divergence within the Eastern North Atlantic is more recent and characterized by isolation by distance. In the present study, phenotypic variation in shell morphology across the North Atlantic range is analysed and compared with molecular divergence. The morphological variation of B. undatum populations reflected the pattern observed for the molecular markers only for certain comparisons of populations and might, in other cases, reflect larger constraints on the morphological variation and, possibly, the impact of environmental influences.

scholarly journals External forcing mechanisms controlling the North Atlantic coastal upwelling regime during the mid-Holocene

Geology ◽  
2020 ◽  
Author(s):  
Armand Hernández ◽  
Mário Cachão ◽  
Pedro Sousa ◽  
Ricardo M. Trigo ◽  
Jürg Luterbacher ◽  
...  
Keyword(s):  
North Atlantic ◽  
Coastal Upwelling ◽  
Marine Ecosystem ◽  
External Forcing ◽  
The North ◽  
New Findings ◽  
The North Atlantic ◽  
Eastern North Atlantic ◽  
Forcing Mechanisms ◽  
The Impact

Nearshore upwelling along the eastern North Atlantic margin regulates regional marine ecosystem productivity and thus impacts blue economies. While most global circulation models show an increase in the intensity and duration of seasonal upwelling at high latitudes under future human-induced warmer conditions, projections for the North Atlantic are still ambiguous. Due to the low temporal resolution of coastal upwelling records, little is known about the impact of natural forcing mechanisms on upwelling variability. Here, we present a microfossil-based proxy record and modeling simulations for the warmest period of the Holocene (ca. 9–5 ka) to estimate the contribution of the natural variability in North Atlantic upwelling via atmospheric and oceanic dynamics. We found that more frequent high-pressure conditions in the eastern North Atlantic associated with solar activity and orbital parameters triggered upwelling variations at multidecadal and millennial time scales, respectively. Our new findings offer insights into the role of external forcing mechanisms in upwelling changes before the Anthropocene, which must be considered when producing future projections of midlatitude upwelling activity.

Preaching and Sermons

2017 ◽  
Author(s):  
Robert H. Ellison
Keyword(s):  
Eighteenth Century ◽  
North Atlantic ◽  
Religious Revival ◽  
Early Nineteenth Century ◽  
Denominational Identity ◽  
The North ◽  
The North Atlantic ◽  
The One ◽  
The Impact

Prompted by the convulsions of the late eighteenth century and inspired by the expansion of evangelicalism across the North Atlantic world, Protestant Dissenters from the 1790s eagerly subscribed to a millennial vision of a world transformed through missionary activism and religious revival. Voluntary societies proliferated in the early nineteenth century to spread the gospel and transform society at home and overseas. In doing so, they engaged many thousands of converts who felt the call to share their experience of personal conversion with others. Though social respectability and business methods became a notable feature of Victorian Nonconformity, the religious populism of the earlier period did not disappear and religious revival remained a key component of Dissenting experience. The impact of this revitalization was mixed. On the one hand, growth was not sustained in the long term and, to some extent, involvement in interdenominational activity undermined denominational identity; on the other hand, Nonconformists gained a social and political prominence they had not enjoyed since the middle of the seventeenth century and their efforts laid the basis for the twentieth-century explosion of evangelicalism in Africa, Asia, and South America.

scholarly journals RAD sequencing of common whelk, Buccinum undatum, reveals fine‐scale population structuring in Europe and cryptic speciation within the North Atlantic

2021 ◽  
Vol 11 (6) ◽  
pp. 2616-2629
Author(s):  
Jake Goodall ◽  
Kristen Marie Westfall ◽  
Hildur Magnúsdóttir ◽  
Snæbjörn Pálsson ◽  
Erla Björk Örnólfsdóttir ◽  
...  
Keyword(s):  
North Atlantic ◽  
Cryptic Speciation ◽  
Rad Sequencing ◽  
Fine Scale ◽  
Buccinum Undatum ◽  
The North ◽  
Scale Population ◽  
Population Structuring ◽  
The North Atlantic

REGIONAL SECURITY DYNAMICS IN NORTHERN EUROPE (ON THE EXAMPLE OF NORWAY) IN THE LIGHT OF RECENT CHANGES

2020 ◽  
Vol 73 (1) ◽  
pp. 103-111
Author(s):  
D. Kalibekuly ◽  
◽  
Y.S. Chukubayev ◽  
Keyword(s):  
North Atlantic ◽  
Member Country ◽  
Security Policy ◽  
Security System ◽  
Regional Security ◽  
Northern Europe ◽  
The North ◽  
The North Atlantic ◽  
The Impact

The paper examines the dynamics of regional security in Norway as a part of Northern Europe. Being a political and geographical part of the Euro-Atlantic security system. Northern Europe, in its turn, is experiencing the impact of the confrontation between Russia and NATO. Norway's security policy analyzed from the perspective of a regional leader, as a NATO member country participating in the operations of the North Atlantic Alliance and as NATO's northern wing.

scholarly journals Climatic impacts of fresh water hosing under Last Glacial Maximum conditions: a multi-model study

2013 ◽  
Vol 9 (2) ◽  
pp. 935-953 ◽  
Author(s):  
M. Kageyama ◽  
U. Merkel ◽  
B. Otto-Bliesner ◽  
M. Prange ◽  
A. Abe-Ouchi ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Fresh Water ◽  
North Atlantic ◽  
Greenland Ice Sheet ◽  
Meridional Overturning Circulation ◽  
Last Glacial ◽  
The North ◽  
Tropical North Atlantic ◽  
The North Atlantic ◽  
The Impact

Abstract. Fresh water hosing simulations, in which a fresh water flux is imposed in the North Atlantic to force fluctuations of the Atlantic Meridional Overturning Circulation, have been routinely performed, first to study the climatic signature of different states of this circulation, then, under present or future conditions, to investigate the potential impact of a partial melting of the Greenland ice sheet. The most compelling examples of climatic changes potentially related to AMOC abrupt variations, however, are found in high resolution palaeo-records from around the globe for the last glacial period. To study those more specifically, more and more fresh water hosing experiments have been performed under glacial conditions in the recent years. Here we compare an ensemble constituted by 11 such simulations run with 6 different climate models. All simulations follow a slightly different design, but are sufficiently close in their design to be compared. They all study the impact of a fresh water hosing imposed in the extra-tropical North Atlantic. Common features in the model responses to hosing are the cooling over the North Atlantic, extending along the sub-tropical gyre in the tropical North Atlantic, the southward shift of the Atlantic ITCZ and the weakening of the African and Indian monsoons. On the other hand, the expression of the bipolar see-saw, i.e., warming in the Southern Hemisphere, differs from model to model, with some restricting it to the South Atlantic and specific regions of the southern ocean while others simulate a widespread southern ocean warming. The relationships between the features common to most models, i.e., climate changes over the north and tropical Atlantic, African and Asian monsoon regions, are further quantified. These suggest a tight correlation between the temperature and precipitation changes over the extra-tropical North Atlantic, but different pathways for the teleconnections between the AMOC/North Atlantic region and the African and Indian monsoon regions.

scholarly journals Impact of Agulhas Leakage on the Atlantic Overturning Circulation in the CCSM4

2014 ◽  
Vol 27 (1) ◽  
pp. 101-110 ◽  
Author(s):  
Wilbert Weijer ◽  
Erik van Sebille
Keyword(s):  
North Atlantic ◽  
South Atlantic ◽  
Meridional Overturning Circulation ◽  
Overturning Circulation ◽  
Climate System Model ◽  
The North ◽  
Salinity Variability ◽  
Meridional Overturning ◽  
The North Atlantic ◽  
The Impact

Abstract The impact of Agulhas leakage variability on the strength of the Atlantic meridional overturning circulation (AMOC) in the Community Climate System Model, version 4 (CCSM4) is investigated. In this model an advective connection exists that transports salinity anomalies from the Agulhas region into the North Atlantic on decadal (30–40 yr) time scales. However, there is no identifiable impact of Agulhas leakage on the strength of the AMOC, suggesting that the salinity variations are too weak to significantly modify the stratification in the North Atlantic. It is argued that this study is inconclusive with respect to an impact of Agulhas leakage on the AMOC. Salinity biases leave the South Atlantic and Indian Oceans too homogeneous, in particular erasing the observed salinity front in the Agulhas retroflection region. Consequently, salinity variability in the southeastern South Atlantic is found to be much weaker than observed.

scholarly journals Multimodel Future Projections of Wintertime North Atlantic and North Pacific Tropospheric Jets: A Bayesian Analysis

2018 ◽  
Vol 31 (6) ◽  
pp. 2533-2545 ◽  
Author(s):  
D. Whittleston ◽  
K. A. McColl ◽  
D. Entekhabi
Keyword(s):  
Greenhouse Gas ◽  
North Atlantic ◽  
North Pacific ◽  
Current Model ◽  
Systematic Bias ◽  
Weighting Method ◽  
The North ◽  
State Dependent ◽  
The North Atlantic ◽  
The Impact

The impact of future greenhouse gas forcing on the North Atlantic and North Pacific tropospheric jets remains uncertain. Opposing changes in the latitudinal temperature gradient—forced by amplified lower-atmospheric Arctic warming versus upper-atmospheric tropical warming—make robust predictions a challenge. Despite some models simulating more realistic jets than others, it remains the prevailing approach to treat each model as equally probable (i.e., democratic weighting). This study compares democratically weighted projections to an alternative Bayesian-weighting method based on the ability of models to simulate historical wintertime jet climatology. The novel Bayesian technique is developed to be broadly applicable to high-dimensional fields. Results show the Bayesian weighting can reduce systematic bias and suggest the wintertime jet response to greenhouse gas forcing is largely independent of this historical bias (i.e., not state dependent). A future strengthening and narrowing is seen in both winter jets, particularly at the upper levels. The widely reported poleward shift at the level of the eddy-driven jet does not appear statistically robust, particularly over the North Atlantic, indicating sensitivity to current model deficiencies.

Long-term ventilation changes of Subpolar Mode Waters in the North Atlantic Ocean and its impact on the oxygen distribution

2021 ◽  
Author(s):  
Ilaria Stendardo ◽  
Bruno Buongiorno Nardelli ◽  
Sara Durante
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Horizontal Resolution ◽  
Late Winter ◽  
Mode Water ◽  
Mode Waters ◽  
The North ◽  
The North Atlantic ◽  
The Impact

<p>In the subpolar North Atlantic Ocean, Subpolar Mode Waters (SPMWs) are formed during late winter convection following the cyclonic circulation of the subpolar gyre. SPMWs participate in the upper flow of the Atlantic overturning circulation (AMOC) and provide much of the water that is eventually transformed into several components of the North Atlantic deep water (NADW), the cold, deep part of the AMOC. In a warming climate, an increase in upper ocean stratification is expected to lead to a reduced ventilation and a loss of oxygen. Thus, understanding how mode waters are affected by ventilation changes will help us to better understand the variability in the AMOC. In particular, we would like to address how the volume occupied by SPMWs has varied over the last decades due to ventilation changes, and what are the aspects driving the subpolar mode water formation, their interannual variations as well as the impact of the variability in the mixing and subduction and vertical dynamics on ocean deoxygenation. For this purpose, we use two observation-based 3D products from Copernicus Marine Service (CMEMS), the ARMOR3D and the OMEGA3D datasets. The first consists of 3D temperature and salinity fields, from the surface to 1500 m depth, available weekly over a regular grid at 1/4° horizontal resolution from 1993 to present. The second consists of observation-based quasi-geostrophic vertical and horizontal ocean currents with the same temporal and spatial resolution as ARMOR3D.</p>

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