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Marine Ecology Progress Series

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MEPS 624:195-212 (2019)  -  DOI:

Spatial structuring and life history connectivity of Antarctic silverfish along the southern continental shelf of the Weddell Sea

Jilda Alicia Caccavo1,2,*, Julian R. Ashford3, Svenja Ryan1, Chiara Papetti4,5, Michael Schröder1, Lorenzo Zane4,5

1Alfred Wegener Institute, Helmholtz Center of Polar and Marine Research, Bremerhaven 27570, Germany
2Berlin Center for Genomics in Biodiversity Research (BeGenDiv), Berlin 14195, Germany
3Department of Ocean, Earth and Atmospheric Sciences, Center for Quantitative Fisheries Ecology, Old Dominion University, Norfolk, VA 23508, USA
4Department of Biology, University of Padua, Padua 35121, Italy
5Consorzio Nazionale Interuniversitario per le Scienze del Mare (CoNISMa), Rome 00196, Italy
*Corresponding author:

ABSTRACT: A multi-disciplinary approach was employed to examine a physical-biological population hypothesis for a critical forage species, the Antarctic silverfish Pleuragramma antarctica. Caccavo et al. (2018; Sci Rep 8:17856) had shown strong gene flow along the westward Antarctic Slope Current, in addition to spatially recurring length modes that provided evidence for episodic connectivity. In this paper, otolith nucleus chemistry from a subset of fish collected in the southern Weddell Sea as part of a hydrographic survey of the Filchner Trough system was used to test between connectivity scenarios. Nucleus chemistry, which reflects environmental exposure during early life, showed significant spatial structuring despite homogeneity in microsatellite allele frequencies. Mg:Ca and Sr:Ca differentiated length modes, and Mg:Ca showed significant contrasts between Atka Bay, Halley Bay, and Filchner Trough. Physical-biological mechanisms may help reconcile structuring shown by otolith chemistry, length, and abundance data with prior evidence of gene flow. Such mechanisms include self-recruitment shaped by circulation associated with the Filchner Trough, fluctuations in mixing between immigrant and locally recruited fish, and feeding opportunities between inflowing Modified Warm Deep Water and outflowing Ice Shelf Water. The results illustrate how comparisons between multi-disciplinary techniques based on integrated sampling designs that incorporate hydrography can enhance understanding of population structure and connectivity around the Southern Ocean.

KEY WORDS: Physical-biological interactions · Filchner Trough · Population structure · Life history connectivity · Trough circulation · Modified Warm Deep Water · MWDW · Ice Shelf Water · ISW · Otolith chemistry

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Cite this article as: Caccavo JA, Ashford JR, Ryan S, Papetti C, Schröder M, Zane L (2019) Spatial structuring and life history connectivity of Antarctic silverfish along the southern continental shelf of the Weddell Sea. Mar Ecol Prog Ser 624:195-212.

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