Short-and long term niche segregation and individual specialization of brown trout (Salmo trutta) in species poor Faroese lakes |
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Authors: | Jakob Brodersen Hilmar J Malmquist Frank Landkildehus Torben L Lauridsen Susanne L Amsinck Rikke Bjerring Martin S?ndergaard Liselotte S Johansson Kirsten S Christoffersen Erik Jeppesen |
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Institution: | (1) Department of Bioscience, Aarhus University, Vejls?vej 25, DK-8600 Silkeborg, Denmark;(2) Department of Biology/Aquatic Ecology, Lund University, 223 62 Lund, Sweden;(3) Natural History Museum of K?pavogur, Hamraborg 6a, IS-200 K?pavogur, Iceland;(4) Freshwater Biological Laboratory, University of Copenhagen, Helsing?rsgade 51, DK-3400 Hiller?d, Denmark;(5) Greenland Climate Research Centre (GCRC), Greenland Institute of Natural Resources, Nuuk, Greenland;(6) The Sino-Danish Center for Education and Research (SDC), Beijing, China;(7) Present address: Department of Fish Ecology and Evolution, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Center of Ecology, Evolution and Biochemistry, Seestrasse 79, CH-6047 Kastanienbaum, Switzerland |
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Abstract: | Trophic niche divergence is considered to be a major process by which species coexistence is facilitated. When studying niche
segregation in lake ecosystems, we tend to view the niche on a one-dimensional pelagic-littoral axis. In reality, however,
the niche use may be more complex and individual fidelity to a niche may be variable both between and within populations.
In order to study this complexity, relative simple systems with few species are needed. In this paper, we study how competitor
presence affects the resource use of brown trout (Salmo trutta) in 11 species-poor Faroese lakes by comparing relative abundance, stable isotope ratios and diet in multiple habitats. In
the presence of three-spined sticklebacks (Gasterosteus aculeatus), a higher proportion of the trout population was found in the pelagic habitat, and trout in general relied on a more pelagic
diet base as compared to trout living in allopatry or in sympatry with Arctic charr (Salvelinus alpinus). Diet analyses revealed, however, that niche-segregation may be more complex than described on a one-dimensional pelagic-littoral
axis. Trout from both littoral and offshore benthic habitats had in the presence of sticklebacks a less benthic diet as compared
to trout living in allopatry or in sympatry with charr. Furthermore, we found individual habitat specialization between littoral/benthic
and pelagic trout in deep lakes. Hence, our findings indicate that for trout populations interspecific competition can drive
shifts in both habitat and niche use, but at the same time they illustrate the complexity of the ecological niche in freshwater
ecosystems. |
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