Competitive effects of fish in structurally simple habitats: perch,invertebrates, and goldeneye in small boreal lakes |
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Authors: | Email author" target="_blank">Petri?NummiEmail author Veli-Matti?V??n?nen Martti?Rask Kari?Nyberg Keijo?Taskinen |
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Institution: | (1) Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 Helsinki, Finland;(2) Finnish Game and Fisheries Research Institute, Evo Game and Fisheries Research, 16970 Evo, Finland;(3) Department of Environmental Sciences, University of Helsinki, P.O. Box 65, 00014 Helsinki, Finland |
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Abstract: | We determined the associations between Eurasian perch Perca fluviatilis, invertebrates, and common goldeneye Bucephala clangula in boreal lakes. Our aim was to test the hypothesis that perch play a controlling role in small, oligotrophic, acidic, and
poorly vegetated boreal lakes, affecting both invertebrate numbers and community structure. In addition, we predicted that
perch impact lake usage by goldeneye. In the observational part of our study, we first explored the association between perch,
invertebrates and goldeneye (pairs and broods per shore km) in 18 boreal, poorly vegetated lakes. Perch densities were associated
negatively with invertebrate abundance and lake usage by goldeneye broods. In the experimental part in three fish-free lakes,
we found that upon successful perch introductions, the number and biomass of invertebrates, the proportion of large dytiscids,
and lake usage by goldeneye broods significantly decreased. We conclude that perch apparently plays a key role as a predator
of invertebrates in boreal lakes with few aquatic macrophytes. It is evident that perch can strongly affect their prey populations
and communities, and this predation may have an indirect effect on species, e.g. goldeneye, that consume the same prey. |
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