Transatlantic movements of juvenile Atlantic bluefin tuna inferred from analyses of organochlorine tracers

2015 ◽  
Vol 72 (4) ◽  
pp. 625-633 ◽  
Author(s):  
John E. Graves ◽  
Andrew S. Wozniak ◽  
Rebecca M. Dickhut ◽  
Michele A. Cochran ◽  
Elizabeth H. MacDonald ◽  
...  
Keyword(s):  
North Atlantic ◽  
Bluefin Tuna ◽  
Fish Tissues ◽  
Atlantic Bluefin Tuna ◽  
The North ◽  
Limited Variation ◽  
The North Atlantic ◽  
Young Of The Year ◽  
Eastern North Atlantic ◽  
Organochlorine Pollutant

Ratios of certain organochlorine pollutants in fish tissues are significantly different between the eastern and western North Atlantic and have been used to identify recent (<1 year) transatlantic migrants of Atlantic bluefin tuna (Thunnus thynnus). In this study we observed limited variation of organochlorine pollutant ratios across collections of young-of-the-year (YOY) bluefin tuna from the western North Atlantic (WNA) and eastern North Atlantic (ENA) in different years and highly significant differences between WNA and ENA YOY samples each year and for all years combined. A significant increase in organochlorine ratios was noted between YOY and age-1 ENA bluefin tuna, consistent with the movement of YOY out of the Mediterranean Sea and into the ENA. Using baseline organochlorine ratios from WNA YOY to identify recent eastern migrants, 29% of age-2, 33% of age-3, and 24% of age-4 juvenile bluefin tuna in the WNA were identified as recent migrants from the east during 2011 and 2012. Applying baseline ratios from age-1 ENA bluefin tuna to identify recent migrants from the WNA, 14.3% of age-2, 9.5% of age-3, and 0% of age-4 juvenile bluefin tuna caught in the Bay of Biscay fishery were identified as recent western migrants during 2010 and 2011. These data reveal substantial connectivity of juvenile bluefin tuna across the North Atlantic and demonstrate that WNA juveniles are heavily subsidized by eastern fish.

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.

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 Declining Mercury Concentrations in Bluefin Tuna Reflect Reduced Emissions to the North Atlantic Ocean

2016 ◽  
Vol 50 (23) ◽  
pp. 12825-12830 ◽  
Author(s):  
Cheng-Shiuan Lee ◽  
Molly E. Lutcavage ◽  
Emily Chandler ◽  
Daniel J. Madigan ◽  
Robert M. Cerrato ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Bluefin Tuna ◽  
The North ◽  
The North Atlantic ◽  
Reduced Emissions

scholarly journals Influence of Storm–Storm and Storm–Environment Interactions on Tropical Cyclone Formation and Evolution

2017 ◽  
Vol 145 (12) ◽  
pp. 4855-4875 ◽  
Author(s):  
James P. Fowler ◽  
Thomas J. Galarneau
Keyword(s):  
North Atlantic ◽  
Vertical Wind Shear ◽  
Meridional Flow ◽  
Easterly Waves ◽  
The North ◽  
Close Proximity ◽  
Formation And Evolution ◽  
The North Atlantic ◽  
Eastern North Atlantic ◽  
Difficult Challenge

The aim of this study is to examine the development of four tropical cyclones (TCs) in the North Atlantic basin in late August and early September 2010. This period is of interest because four consecutive easterly waves emerged from West Africa and resulted in a multiple TC event (MTCE) over the North Atlantic. The first two TCs—Danielle and Earl—quickly developed into TCs east of 40°W and eventually intensified into major hurricanes. Conversely, the last two TCs—Fiona and Gaston—developed more slowly reaching only weak tropical storm intensity at their peak. The close proximity and differing evolution of these four TCs provides a unique opportunity to examine how these TCs interacted with each other and their surrounding environment, which influenced their development as they moved westward across the North Atlantic. The results showed that concurrent extratropical cyclogenesis events over the western and eastern North Atlantic and the recurvature of TC Danielle produced increased meridional flow over the midlatitude North Atlantic. This increased meridional flow resulted in subsynoptic-scale regions of increased vertical wind shear in the subtropics, which delayed Earl’s development and led to Fiona’s demise. Additionally, increased meridional flow in midlatitudes contributed to anomalous drying of the subtropics. This dry air was entrained into Gaston’s circulation leading to reduced convection and weakening. These TC–TC and TC–environment interactions highlight the difficult challenge of forecasting TC genesis and position posed by MTCEs in a rapidly evolving synoptic-scale flow.

scholarly journals Longitude-dependent decadal ozone changes and ozone trends in boreal winter months during 1960–2000

2008 ◽  
Vol 26 (5) ◽  
pp. 1275-1286 ◽  
Author(s):  
D. H. W. Peters ◽  
A. Gabriel ◽  
G. Entzian
Keyword(s):  
Rossby Wave ◽  
North Atlantic ◽  
Total Ozone ◽  
Planetary Wave ◽  
Wave Structure ◽  
Boreal Winter ◽  
The North ◽  
The North Atlantic ◽  
Eastern North Atlantic ◽  
The 1960S

Abstract. This study examines the longitude-dependent decadal changes and trends of ozone for the boreal winter months during the period of 1960–2000. These changes are caused primarily by changes in the planetary wave structure in the upper troposphere and lower stratosphere. The decadal changes and trends over 4 decades of geopotential perturbations, defined as a deviation from the zonal mean, are estimated by linear regression with time. The decadal changes in longitude-dependent ozone were calculated with a simple transport model of ozone based on the known planetary wave structure changes and prescribed zonal mean ozone gradients. For December of the 1960s and 1980s a statistically significant Rossby wave track appeared over the North Atlantic and Europe with an anticyclonic disturbance over the Eastern North Atlantic and Western Europe, flanked by cyclonic disturbances. In the 1970s and 1990s statistically significant cyclonic disturbances appeared over the Eastern North Atlantic and Europe, surrounded by anticyclonic anomalies over Northern Africa, Central Asia and Greenland. Similar patterns have been found for January. The Rossby wave track over the North Atlantic and Europe is stronger in the 1980s than in the 1960s. For February, the variability of the regression patterns is higher. For January we found a strong alteration in the modelled decadal changes in total ozone over Central and Northern Europe, showing a decrease of about 15 DU in the 1960s and 1980s and an increase of about 10 DU in the 1970s and 1990s. Over Central Europe the positive geopotential height trend (increase of 2.3 m/yr) over 40 years is of the same order (about 100 m) as the increase in the 1980s alone. This is important to recognize because it implies a total ozone decrease over Europe of the order of 14 DU for the 1960–2000 period, for January, if we use the standard change regression relation that about a 10-m geopotential height increase at 300 hPa is related to about a 1.4-DU total ozone decrease.

scholarly journals The silicon stable isotope distribution along the GEOVIDE section (GEOTRACES GA-01) of the North Atlantic Ocean

2018 ◽  
Vol 15 (18) ◽  
pp. 5663-5676 ◽  
Author(s):  
Jill N. Sutton ◽  
Gregory F. de Souza ◽  
Maribel I. García-Ibáñez ◽  
Christina L. De La Rocha
Keyword(s):  
Stable Isotope ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
Deep Water ◽  
North Atlantic Ocean ◽  
Water Masses ◽  
Labrador Sea ◽  
The North ◽  
The North Atlantic ◽  
Eastern North Atlantic

Abstract. The stable isotope composition of dissolved silicon in seawater (δ30SiDSi) was examined at 10 stations along the GEOVIDE section (GEOTRACES GA-01), spanning the North Atlantic Ocean (40–60∘ N) and Labrador Sea. Variations in δ30SiDSi below 500 m were closely tied to the distribution of water masses. Higher δ30SiDSi values are associated with intermediate and deep water masses of northern Atlantic or Arctic Ocean origin, whilst lower δ30SiDSi values are associated with DSi-rich waters sourced ultimately from the Southern Ocean. Correspondingly, the lowest δ30SiDSi values were observed in the deep and abyssal eastern North Atlantic, where dense southern-sourced waters dominate. The extent to which the spreading of water masses influences the δ30SiDSi distribution is marked clearly by Labrador Sea Water (LSW), whose high δ30SiDSi signature is visible not only within its region of formation within the Labrador and Irminger seas, but also throughout the mid-depth western and eastern North Atlantic Ocean. Both δ30SiDSi and hydrographic parameters document the circulation of LSW into the eastern North Atlantic, where it overlies southern-sourced Lower Deep Water. The GEOVIDE δ30SiDSi distribution thus provides a clear view of the direct interaction between subpolar/polar water masses of northern and southern origin, and allow examination of the extent to which these far-field signals influence the local δ30SiDSi distribution.

Observations on the Vertical Distribution of the Genus Acanthephyra (Crustacea: Decapoda) in the eastern North Atlantic, with particular reference to Species of the ‘purpurea’ Group.

1972 ◽  
Vol 73 ◽  
pp. 301-313 ◽  
Author(s):  
P. Foxton
Keyword(s):  
Vertical Distribution ◽  
North Atlantic ◽  
South Atlantic ◽  
The North ◽  
Mesopelagic Zone ◽  
Vertical Distributions ◽  
The North Atlantic ◽  
Eastern North Atlantic ◽  
The Vertical Distribution ◽  
Mesopelagic Species

SynopsisThe vertical distribution of pelagic decapods has been investigated at six positions, each located approximately at 10° interval of latitude between 11°N and 60°N in the eastern North Atlantic. An account of the day and night depth distribution of four mesopelagic species, Acanthephyra purpurea, A. pelagica, A. sexspinosa and A. acanthitelsonis, and four bathypelagic species, A. prionota, A. curtirostris, A. acutifrons and A. stylorostratis, is presented. The four mesopelagic species have vertical distributions which vary latitudinally in association with geographical gradients in temperature, the mesopelagic zone from about the latitude of 28°N cooling both polewards and equatorwards. It is concluded that environmental temperature is a major factor in controlling the vertical ranges of these species although other physical variables, principally light, must also be involved.A faunal boundary exists in the region of 18°N, where the North Atlantic species A. purpurea and A.pelagica are replaced by the Central and South Atlantic species A. sexspinosa and A. acanthitelsonis. The nature of the physical boundary is not clear, but it is tentatively proposed that it represents a relatively broad area where the North Atlantic Central Water and South Atlantic Central Water meet.

On the Temporally Varying Northward Penetration of Mediterranean Overflow Water and Eastward Penetration of Labrador Sea Water

2008 ◽  
Vol 38 (9) ◽  
pp. 2097-2103 ◽  
Author(s):  
M. Susan Lozier ◽  
Nicole M. Stewart
Keyword(s):  
North Atlantic ◽  
Water Mass ◽  
Sea Water ◽  
Labrador Sea ◽  
Subpolar Gyre ◽  
The North ◽  
The North Atlantic ◽  
Eastern North Atlantic ◽  
The North Atlantic Oscillation ◽  
Water Mass Transformations

Abstract Historical hydrographic data in the eastern North Atlantic are used to suggest a connection between the northward penetration of Mediterranean Overflow Water (MOW) and the location of the subpolar front, the latter of which is shown to vary with the North Atlantic Oscillation (NAO). During persistent high-NAO periods, when the subpolar front moves eastward, waters in the subpolar gyre essentially block the northward-flowing MOW, preventing its entry into the subpolar gyre. Conversely, during low NAO periods, the subpolar front moves westward, allowing MOW to penetrate past Porcupine Bank into the subpolar gyre. The impacts of an intermittent penetration of MOW into the subpolar gyre, including the possible effect on water mass transformations, remain to be investigated.

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