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  • 1
    Call number: ZSP-168-124
    In: Berichte zur Polarforschung
    Type of Medium: Series available for loan
    Pages: XI, 141, [57] S. : graph. Darst., Kt.
    ISSN: 0176-5027
    Series Statement: Berichte zur Polarforschung 124
    Language: German
    Note: Zugl.: Bremen, Univ., Diss., 1992
    Location: Reading room
    Branch Library: AWI Library
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  • 2
    Publication Date: 2019-02-06
    Type: Dataset
    Format: text/tab-separated-values, 70 data points
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  • 3
    Publication Date: 2018-09-27
    Type: Dataset
    Format: text/tab-separated-values, 58 data points
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  • 4
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    PANGAEA
    In:  Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven
    Publication Date: 2019-01-27
    Type: Dataset
    Format: text/tab-separated-values, 184938 data points
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  • 5
    Publication Date: 2016-08-26
    Description: Ongoing ocean warming and acidification have been found to particularly affect polar marine ecosystems. However, few data exist about the ability of Antarctic fish to respond to environmental change. We therefore studied the acclimatory capacities of the Antarctic fish Notothenia rossii after 4-6 weeks of acclimation to 7°C, hypercapnia (0.2 kPa CO2) and the combination of both. We analysed routine metabolic rate (RMR) during acute thermal challenge and after acclimation, extra- and intracellular acid-base status, mitochondrial as well as enzymatic capacities and lipid composition. Our results showed partially compensated RMR after warm acclimation and no effect of increased PCO2 on the RMR. Hypercapnic acclimation led to a general overcompensation of extracellular pH. Intracellular pH displayed a slight acidosis in liver after warm normocapnic/hypercapnic acclimation, whereas white muscle remained well buffered under hypercapnia. Mitochondrial state III respiration in liver was unaffected by temperature acclimation, but depressed in the hypercapnia acclimated animals, which went along with reduced rates of proton leak. The activities of the mitochondrial enzymes citrate synthase and cytochrome c oxidase increased during hypercapnia acclimation in red and white muscle, but not in liver and heart. Furthermore, there was a trend towards an enrichment of poly-unsaturated fatty acids in liver mitochondria towards the warm hypercapnic conditions. We conclude that N. rossii possesses basic acclimatory capacities towards ocean warming and acidification. However, these capacities are confined within strict limits, becoming obvious in metabolically more active organs like heart and liver that show less plasticity than muscle and ultimately define animal survival.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 6
    Publication Date: 2014-08-26
    Description: The high Arctic Kongsfjorden (79°N) is mainly influenced by cold Arctic but also warmer Atlantic water masses. In recent years, the proportion of Atlantic inflow increased, attributed to climate change. Concurrently, two boreal and one subtropical krill species are now being regularly found in Kongsfjorden – in addition to the previously prevailing arcto-boreal species Thysanoessa inermis and T. raschii (Buchholz et al. 2010). Krill occupy a central trophic position in the pelagic food-web. Although a change in a krill population may have a significant impact on the ecosystem, knowledge on the physiological performance of the species inhabiting Arctic waters is still scarce. In our study we aim at investigating the thermal limits of metabolic adaptability and the allocation of energy reserves in order to predict each species’ potential to persist in this challenging environment, in which temperature and food supply are among the most important factors determining survival. Total lipid content and lipid class composition show remarkable differences between species, reflecting the specific adaptations to the environments of origin. Furthermore, Thysanoessa spp. appear more stenotherm than the boreal and the subtropical krill species: the upper level of respiration is reached at temperatures 〈 12°C (Fig. 1). The other krill species show a higher tolerance to temperature changes, which may support the species’ success in northward expansion as reported through increasing abundances at lower latitudes (e.g. Zhukova et al. 2009). Accordingly, at least one of the latter species may profit from the increasing “Atlantification” of the Kongsfjord ecosystem. In turn, due to the differences in biochemical composition, a change in species composition may result in significant changes in the marine food-web of Kongsfjorden - especially for higher trophic levels.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 7
    Publication Date: 2017-01-24
    Description: Our study deals with the lipid biochemistry of the krill community in the ecosystem of the high Arctic Kongsfjord (Svalbard). During the last decades, Kongsfjord experienced a change in krill species composition due to recent increased advection of Atlantic water masses carrying characteristic boreal as well as subtropical-boreal euphausiids into the ecosystem. The lipid biochemistry and trophic relationships of the species recently inhabiting the Arctic water masses are scarcely known, although a change in a krill population may have a significant impact on the ecosystem. A comparison of nutrition and energy storage strategies, stable isotopes, lipid profiles and fatty acid compositions showed remarkable differences between the krill species. These reflected the diverse feeding behaviours and specific adaptations to the environments of their origin: the boreal Meganyctiphanes norvegica and subtropical Nematoscelis megalops appear more carnivorous, have significantly lower mean lipid contents (29 % and 10 %, respectively) and a different energy storage pattern (triacylglycerols and polar lipids, respectively) than the arcto-boreal Thysanoessa inermis, which consists of up to 54 % of lipids mainly stored as wax esters (〉 40 %). These differences may have significant implications for the rapidly changing marine food-web of Kongsfjord - especially for higher trophic levels relying on the nutritional input of animal lipids.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 8
    Publication Date: 2015-07-06
    Description: ABSTRACT: Mediterranean Posidonia oceanica meadows shelter a high biomass and an important biodiversity of amphipod crustaceans. In other temperate meadows, the amphipods play an important part in the functioning of the ecosystem, notably in organic matter transfers from producers to higher level consumers. However, the situation in Posidonia oceanica meadows remains unclear, and little is known about the trophic ecology of amphipods, which are generally regarded as generalist herbivores/detritivores despite the lack of precise studies. Here, we combined gut content examination and trophic markers (fatty acids, stables isotopes of C and N) to delineate the diet of the dominant species of amphipods from Posidonia oceanica seagrass meadows and to highlight trophic diversity among this community. Our results indicate that contribution of microepiphytic diatoms and of benthic and suspended particulate organic matter to the diet of amphipods were anecdotal. On the other hand, all dominant species heavily relied on macroalgal epiphytes, suggesting a certain extent of overlapping in the diets of the dominant species. Considerable interspecific differences nonetheless existed, notably concerning grazing preferences towards epiphytes from leaves or litter fragments vs. epiphytes from rhizomes. In addition, the use of the SIAR isotopic mixing model showed that most species had a mixed diet, and relied on several food items. None of the examined species seemed to graze on their seagrass host, but Gammarus aequicauda partly relied on seagrass leaf detritus. Overall, our findings demonstrate that amphipods have the potential to be key-items in trophic and functional interactions occurring among Mediterranean Posidonia oceanica meadows. 8th International Conference on Applications of Stable Isotope Techniques to Ecological Studies (IsoEcol), Brest, France; 08/2012
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 9
    Publication Date: 2015-02-17
    Description: The copepod Calanus glacialis comprises up to 80% of the zooplankton biomass in Arctic shelf seas and plays a key role in Arctic marine ecosystems. It is primarily a grazer, accumulating essential polyunsaturated fatty acids from its algal diet as well as converting low-energy carbohydrates and proteins in algae into high-energy wax ester lipids. It is able to survive long periods without food by descending to depth and lowering its metabolism to a minimum, a state referred to as diapause. Although C. glacialis may be in this physiological state for up to 8 months each year we know very little about the energetic costs required during diapause. We therefore initiated an extensive field campaign in a high-Arctic fjord, sampling the local population monthly from June 2012 to July 2013. Monthly carbon demand was estimated by measuring respiration, image analysis was used to analyse variability in lipid content over the season. The carbon demand during winter differed among C. glacialis CIV, CV, females and males, with CV and adults being active much earlier previously assumed. Lipid reserves in CV and females remain largely untouched throughout autumn but decrease from January on, most likely to fuel moulting and maturation. The C. glacialis population declined steeply from January to May suggesting that individuals may run out of energy stores during winter. Of the verwintering stages, only IV seems to stay in diapause over an extended period, utilizing little of its lipid storage from fall through winter
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 10
    Publication Date: 2015-03-23
    Description: Calanus glacialis dominates the zooplankton communities on the Arctic Shelf and plays a key role in Arctic food webs. To overwinter, most juvenile copepods (CV) migrate to deeper waters. Metabolic activity is low at that time but nevertheless the gonads start developing fuelled by internal reserves. The timing of this process is not yet known in C. glacialis from the high Arctic although this information would help to fully understand the physiological characteristics of the overwintering copepods. We therefore sampled the same population in the Billefjorden (Svalbard) from June 2012 to July 2013 and studied the gonad morphology in CV. In summer and early autumn, few cells were visible in the gonads. In late autumn, gonads increased in size in CV remaining at the surface and in CV residing at 〉100m depth. Gonads of CV were largest in January and at that time moulting to adults started. Lipids fuelled gonad growth, as lipid contents decreased from 41% to 20% of dry mass. Our data suggest that gonad development was independent from ambient conditions but triggered internally.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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