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  • 1
    In: Freshwater Biology, Wiley, Vol. 67, No. 1 ( 2022-01), p. 141-158
    Kurzfassung: Arctic freshwaters are facing multiple environmental pressures, including rapid climate change and increasing land___use activities. Freshwater plankton assemblages are expected to reflect the effects of these stressors through shifts in species distributions and changes to biodiversity. These changes may occur rapidly due to the short generation times and high dispersal capabilities of both phyto___ and zooplankton. Spatial patterns and contemporary trends in plankton diversity throughout the circumpolar region were assessed using data from more than 300 lakes in the U.S.A. (Alaska), Canada, Greenland, Iceland, the Faroe Islands, Norway, Sweden, Finland, and Russia. The main objectives of this study were: (1) to assess spatial patterns of plankton diversity focusing on pelagic communities; (2) to assess dominant component of __ diversity (turnover or nestedness); (3) to identify which environmental factors best explain diversity; and (4) to provide recommendations for future monitoring and assessment of freshwater plankton communities across the Arctic region. Phytoplankton and crustacean zooplankton diversity varied substantially across the Arctic and was positively related to summer air temperature. However, for zooplankton, the positive correlation between summer temperature and species numbers decreased with increasing latitude. Taxonomic richness was lower in the high Arctic compared to the sub___ and low Arctic for zooplankton but this pattern was less clear for phytoplankton. Fennoscandia and inland regions of Russia represented hotspots for, respectively, phytoplankton and zooplankton diversity, whereas isolated regions had lower taxonomic richness. Ecoregions with high __ diversity generally also had high __ diversity, and turnover was the most important component of __ diversity in all ecoregions. For both phytoplankton and zooplankton, climatic variables were the most important environmental factors influencing diversity patterns, consistent with previous studies that examined shorter temperature gradients. However, barriers to dispersal may have also played a role in limiting diversity on islands. A better understanding of how diversity patterns are determined by colonisation history, environmental variables, and biotic interactions requires more monitoring data with locations dispersed evenly across the circumpolar Arctic. Furthermore, the importance of turnover in regional diversity patterns indicates that more extensive sampling is required to fully characterise the species pool of Arctic lakes.
    Materialart: Online-Ressource
    ISSN: 0046-5070 , 1365-2427
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2022
    ZDB Id: 2020306-8
    ZDB Id: 121180-8
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Online-Ressource
    Online-Ressource
    Wiley ; 2022
    In:  Limnology and Oceanography Vol. 67, No. 4 ( 2022-04), p. 843-855
    In: Limnology and Oceanography, Wiley, Vol. 67, No. 4 ( 2022-04), p. 843-855
    Kurzfassung: Understanding how marine microbial food webs and their ecosystem functions are changing is crucial for projections of the future ocean. Often, simplified food web models are employed and their solutions are only evaluated against available observations of plankton biomass. With such an approach, it remains unclear how different underlying trophic interactions affect interpretations of plankton dynamics and functioning. Here, we quantitatively compare four hypothetical food webs to data from an existing mesocosm experiment using a refined version of the Minimum Microbial Food Web model. Food web representations range from separated food chains to complex food webs featuring additional trophic links including intraguild predation (IGP). Optimization against observations and taking into account model complexity ensures a fair comparison of the different food webs. Although the different optimized model food webs capture the observations similarly well, projected ecosystem functions differ depending on the underlying food web structure and the presence or absence of IGP. Mesh‐like food webs dominated by the microbial loop yield higher recycling and net primary production (NPP) than models dominated by the classical diatom‐copepod food chain. A high degree of microzooplankton IGP increases NPP and organic matter recycling, but decreases trophic transfer efficiency (TTE) to copepods. Copepod production, the trophic role of copepods, and TTE are more sensitive to initial biomass changes in chain‐like than in complex food webs. Measurements resolving trophic interactions, in particular those quantifying IGP, remain essential to reduce model uncertainty and allow sound conclusions for ecosystem functioning in plankton ecosystems.
    Materialart: Online-Ressource
    ISSN: 0024-3590 , 1939-5590
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2022
    ZDB Id: 2033191-5
    ZDB Id: 412737-7
    SSG: 12
    SSG: 14
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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