The crayfish distribution, feeding plasticity, seasonal isotopic variation and trophic role across ontogeny and habitat
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The crayfish distribution, feeding plasticity, seasonal isotopic variation and trophic role across ontogeny and habitat in a canyon-shaped reservoir Luka´sˇ Vesely´ . Fabio Ercoli . Timo J. Ruokonen . Martin Bla´ha . Jan Kubec . Milosˇ Burˇicˇ . Heikki Ha¨ma¨la¨inen . Antonı´n Kouba
Received: 11 October 2019 / Accepted: 1 October 2020 Ó Springer Nature B.V. 2020
Abstract Man-made reservoirs are important freshwater ecosystems as they are globally common and share features of both standing and running waters. In streams and lakes, crayfish are an important component of freshwater ecosystems due to their habitatmodifying behaviour, substantial size, omnivorous feeding and often high abundance; however, their trophic role in reservoirs is not known. We evaluated the distribution and diet of noble crayfish (Astacus astacus) in the canyon-shaped, oligotrophic Ny´rsko Handling Editor: Te´lesphore Sime-Ngando.
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10452-020-09801-w) contains supplementary material, which is available to authorized users. L. Vesely´ (&) M. Bla´ha J. Kubec M. Burˇicˇ A. Kouba South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Faculty of Fisheries and Protection of Waters, University of South Bohemia in Cˇeske´ Budeˇjovice, Za´tisˇ´ı 728/II, 38925 Vodnˇany, Czech Republic e-mail: [email protected]
reservoir in West Bohemia region, Czech Republic. Using stable isotope analysis, we quantified the trophic level of all major components of the reservoir food web and investigated seasonal isotopic variation and how the trophic role of noble crayfish varied with habitat and ontogeny. Crayfish were an important food source for both predatory and omnivorous fish and consumed food sources from multiple trophic levels, including detritus, algae, zoobenthos and other crayfish. Throughout ontogeny, crayfish had similar levels of carnivory, but cannibalism was more prevalent in adult crayfish, while juveniles and sub-adults fed more on other zoobenthos. Moreover, crayfish had high feeding plasticity in time, as the relative importance of dominant food sources varied with season. Their feeding plasticity was especially evident in crayfish F. Ercoli Chair of Hydrobiology and Fishery, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 5, 51006 Tartu, Estonia T. J. Ruokonen Natural Resources Finland, Jyva¨skyla¨, Survontie 9 A, 40500 Jyvaskyla, Finland
F. Ercoli T. J. Ruokonen H. Ha¨ma¨la¨inen Department of Biological and Environmental Science, University of Jyva¨skyla¨, P.O. Box 35, 40014 Jyvaskyla, Finland
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populations from different habitats, which adapted their feeding strategy to local resources. In addition, pelagic source usage increased with the depth as detritus and algae usage decreased. Proportion of females increased with the depth, while population density showed a unimodal response to the depth
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