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The Bransfield Current System
Deep-Sea Research I 58 (2011) 390–402 Contents lists available at ScienceDirect Deep-Sea Research I journal homepage: www.elsevier.com/locate/dsri The Bransfield current system Pablo Sangra a,n, Carmen Gordo a,Mo´ nica Herna´ndez-Arencibia a, Angeles Marrero-Dı´az a, Angel Rodrı´guez-Santana a, Alexander Stegner b,c, Antonio Martı´nez-Marrero a, Josep L. Pelegrı´ d, Thierry Pichon c a Departamento de Fı´sica, Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas, Spain b Laboratoire de Me´te´orologie Dynamique (LMD), CNRS, Ecole Polytechnique, 91128 Palaiseau, France c Unite´ de Me´canique (UME), ENSTA Chemin de la Huniere, 91126 Palaiseau, France d Departament d’Oceanografı´aFı´sica, Institut de Ciencies del Mar, CSIC, Spain article info abstract Article history: We use hydrographic data collected during two interdisciplinary cruises, CIEMAR and BREDDIES, to Received 24 July 2010 describe the mesoscale variability observed in the Central Basin of the Bransfield Strait (Antarctica). The Received in revised form main mesoscale feature is the Bransfield Front and the related Bransfield Current, which flows 16 December 2010 northeastward along the South Shetland Island Slope. A laboratory model suggests that this current Accepted 25 January 2011 behaves as a gravity current driven by the local rotation rate and the density differences between the Available online 19 February 2011 Transitional Zonal Water with Bellingshausen influence (TBW) and the Transitional Zonal Water with Keywords: Weddell Sea influence (TWW). Below the Bransfield Front we observe a narrow (10 km wide) tongue of Bransfield Strait Circumpolar Deep Water all along the South Shetland Islands Slope. -
Along-Shelf Connectivity and Circumpolar Gene Flow in Antarctic
www.nature.com/scientificreports OPEN Along-shelf connectivity and circumpolar gene fow in Antarctic silverfsh (Pleuragramma Received: 16 March 2018 Accepted: 12 November 2018 antarctica) Published: xx xx xxxx Jilda Alicia Caccavo 1, Chiara Papetti1,2, Maj Wetjen3, Rainer Knust4, Julian R. Ashford5 & Lorenzo Zane1,2 The Antarctic silverfsh (Pleuragramma antarctica) is a critically important forage species with a circumpolar distribution and is unique among other notothenioid species for its wholly pelagic life cycle. Previous studies have provided mixed evidence of population structure over regional and circumpolar scales. The aim of the present study was to test the recent population hypothesis for Antarctic silverfsh, which emphasizes the interplay between life history and hydrography in shaping connectivity. A total of 1067 individuals were collected over 25 years from diferent locations on a circumpolar scale. Samples were genotyped at ffteen microsatellites to assess population diferentiation and genetic structuring using clustering methods, F-statistics, and hierarchical analysis of variance. A lack of diferentiation was found between locations connected by the Antarctic Slope Front Current (ASF), indicative of high levels of gene fow. However, gene fow was signifcantly reduced at the South Orkney Islands and the western Antarctic Peninsula where the ASF is absent. This pattern of gene fow emphasized the relevance of large-scale circulation as a mechanism for circumpolar connectivity. Chaotic genetic patchiness characterized population structure over time, with varying patterns of diferentiation observed between years, accompanied by heterogeneous standard length distributions. The present study supports a more nuanced version of the genetic panmixia hypothesis that refects physical-biological interactions over the life history. -