Flores Hauke

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  • Article
    Allometric relationships of ecologically important Antarctic and Arctic zooplankton and fish species
    (Springer, 2022-01-08) Schaafsma, Fokje L. ; David, Carmen L. ; Kohlbach, Doreen ; Ehrlich, Julia ; Castellani, Giulia ; Lange, Benjamin A. ; Vortkamp, Martina ; Meijboom, André ; Fortuna-Wünsch, Anna ; Immerz, Antonia ; Cantzler, Hannelore ; Klasmeier, Apasiri ; Zakharova, Nadezhda ; Schmidt, Katrin ; Van de Putte, Anton ; van Franeker, Jan A. ; Flores, Hauke
    Allometric relationships between body properties of animals are useful for a wide variety of purposes, such as estimation of biomass, growth, population structure, bioenergetic modelling and carbon flux studies. This study summarizes allometric relationships of zooplankton and nekton species that play major roles in polar marine food webs. Measurements were performed on 639 individuals of 15 species sampled during three expeditions in the Southern Ocean (winter and summer) and 2374 individuals of 14 species sampled during three expeditions in the Arctic Ocean (spring and summer). The information provided by this study fills current knowledge gaps on relationships between length and wet/dry mass of understudied animals, such as various gelatinous zooplankton, and of animals from understudied seasons and maturity stages, for example, for the krill Thysanoessa macrura and larval Euphausia superba caught in winter. Comparisons show that there is intra-specific variation in length–mass relationships of several species depending on season, e.g. for the amphipod Themisto libellula. To investigate the potential use of generalized regression models, comparisons between sexes, maturity stages or age classes were performed and are discussed, such as for the several krill species and T. libellula. Regression model comparisons on age classes of the fish E. antarctica were inconclusive about their general use. Other allometric measurements performed on carapaces, eyes, heads, telsons, tails and otoliths provided models that proved to be useful for estimating length or mass in, e.g. diet studies. In some cases, the suitability of these models may depend on species or developmental stages.
  • Article
    Reviews and syntheses: a framework to observe, understand and project ecosystem response to environmental change in the East Antarctic Southern Ocean
    (European Geosciences Union, 2022-11-23) Gutt, Julian ; Arndt, Stefanie ; Barnes, David Keith Alan ; Bornemann, Horst ; Brey, Thomas ; Eisen, Olaf ; Institute, Hauke ; Griffiths, Huw ; Institute, Christian ; Hain, Stefan ; Hattermann, Tore ; Held, Christoph ; Hoppema, Mario ; Isla, Enrique ; Janout, Markus ; Le Bohec, Céline ; Link, Heike ; Mark, Felix Christopher ; Moreau, Sebastien ; Trimborn, Scarlett ; Van Opzeeland, Ilse ; Pörtner, Hans-Otto ; Schaafsma, Fokje ; Teschke, Katharina ; Tippenhauer, Sana ; Van De Putte, Anton ; Wege, Mia ; Zitterbart, Daniel ; Piepenburg, Dieter
    Systematic long-term studies on ecosystem dynamics are largely lacking from the East Antarctic Southern Ocean, although it is well recognized that they are indispensable to identify the ecological impacts and risks of environmental change. Here, we present a framework for establishing a long-term cross-disciplinary study on decadal timescales. We argue that the eastern Weddell Sea and the adjacent sea to the east, off Dronning Maud Land, is a particularly well suited area for such a study, since it is based on findings from previous expeditions to this region. Moreover, since climate and environmental change have so far been comparatively muted in this area, as in the eastern Antarctic in general, a systematic long-term study of its environmental and ecological state can provide a baseline of the current situation, which will be important for an assessment of future changes from their very onset, with consistent and comparable time series data underpinning and testing models and their projections. By establishing an Integrated East Antarctic Marine Research (IEAMaR) observatory, long-term changes in ocean dynamics, geochemistry, biodiversity, and ecosystem functions and services will be systematically explored and mapped through regular autonomous and ship-based synoptic surveys. An associated long-term ecological research (LTER) programme, including experimental and modelling work, will allow for studying climate-driven ecosystem changes and interactions with impacts arising from other anthropogenic activities. This integrative approach will provide a level of long-term data availability and ecosystem understanding that are imperative to determine, understand, and project the consequences of climate change and support a sound science-informed management of future conservation efforts in the Southern Ocean.