Mesozooplankton succession in a sub-Antarctic bay (Beagle channel, Southern tip of South America): distinctive annual pa
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ORIGINAL PAPER
Mesozooplankton succession in a sub‑Antarctic bay (Beagle channel, Southern tip of South America): distinctive annual patterns between two environmentally different zones María Laura Presta1 · Mónica Susana Hoffmeyer2,3 · Fabiana Lía Capitanio1 Received: 22 May 2019 / Revised: 2 May 2020 / Accepted: 15 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Frequent sampling of zooplankton is essential to understand their annual dynamics. However, in polar and subpolar ecosystems, such sampling is rare. This study comparatively analysed, for the first time, the annual mesozooplankton succession in the northwest nearshore and external zones of Ushuaia Bay in the sub-Antarctic Beagle Channel by monthly sampling over two years. The nearshore zone, with shallow waters and strong continental and anthropogenic influence, was characterised by the year-round occurrence of the euryhaline copepod Eurytemora americana and adventitious taxa. The mesozooplankton community exhibited pronounced monthly and year-to-year variability but, as a general seasonal trend, winter assemblages were dominated by the copepod Oithona similis and adventitious nematodes, whereas the spring–summer ones were dominated by E. americana, the cladoceran Podon leuckarti and Cirripedia nauplii. In the external zone, the copepods Drepanopus forcipatus and Ctenocalanus citer were found throughout the year. The annual succession showed a clearer seasonal pattern. Main shifts in community structure occurred in late winter–spring and late summer–autumn, when a high representation of meroplankton and appendicularians was closely associated with phytoplankton blooms. The higher temporal variability in the nearshore community was partially related to variable contributions of adventitious taxa to assemblage composition and may be also reflecting stressful conditions for plankton species linked to freshwater and urban discharges reported within the bay. This study allowed filling the temporal gaps in previous research and providing a more complete picture of the annual mesozooplankton dynamics in the Beagle Channel, generating hypotheses at the community and population levels for future research. Keywords Monthly sampling · Mesozooplankton dynamics · Ushuaia Bay · Year-to-year variability · Sub-Antarctic fjords
Introduction Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00300-020-02698-z) contains supplementary material, which is available to authorized users. * María Laura Presta [email protected] 1
Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires & Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), CONICET-UBA, C1428EGA Buenos Aires, Argentina
2
Instituto Argentino de Oceanografía, CONICET-UNS, Bahía Blanca, Argentina
3
Facultad Regional Bahía Blanca, Universidad Tecnológica Nacional, Bahía Blanca, Argentina
At mid and high latitudes, a substantial part o
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