The crayfish distribution, feeding plasticity, seasonal isotopic variation and trophic role across ontogeny and habitat in a canyon-shaped reservoir
Laen...
Kuupäev
2020
Kättesaadav alates
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Springer
Abstrakt
Man-made reservoirs are important fresh-water 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 habitat-
modifying 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 Nýrsko 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 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
gradient. These findings indicate that crayfish are
indeed ecologically important species with both direct
and indirect roles in the trophic web of this reservoir
ecosystem.
This study was supported by the Ministry of Education, Youth, and Sports of the Czech Republic (Projects CENAKVA – CZ.1.05/2.1.00/01.0024, and CENAKVA II – LO1205 under the NPU I Programme). We also thank two anonymous reviewers for helpful comments. The authors declare no potential sources of conflict of interest.
This study was supported by the Ministry of Education, Youth, and Sports of the Czech Republic (Projects CENAKVA – CZ.1.05/2.1.00/01.0024, and CENAKVA II – LO1205 under the NPU I Programme). We also thank two anonymous reviewers for helpful comments. The authors declare no potential sources of conflict of interest.
Kirjeldus
Märksõnad
stable isotopes, reservoir, trophic chain, depth distribution, season, habitat, Astacus astacus