21198589
not annotated - annotated - LINNAEUS only
Ice-cover effects on competitive interactions between two fish species.
1. Variations in the strength of ecological interactions between seasons have received little attention, despite an increased focus on climate alterations on ecosystems. Particularly, the winter situation is often neglected when studying competitive interactions. In northern temperate freshwaters, winter implies low temperatures and reduced food availability, but also strong reduction in ambient light because of ice and snow cover. Here, we study how brown trout [Salmo trutta (L.)] respond to variations in ice-cover duration and competition with Arctic charr [Salvelinus alpinus (L.)], by linking laboratory-derived physiological performance and field data on variation in abundance among and within natural brown trout populations. 2. Both Arctic charr and brown trout reduced resting metabolic rate under simulated ice-cover (darkness) in the laboratory, compared to no ice (6-h daylight). However, in contrast to brown trout, Arctic charr was able to obtain positive growth rate in darkness and had higher food intake in tank experiments than brown trout. Arctic charr also performed better (lower energy loss) under simulated ice-cover in a semi-natural environment with natural food supply. 3. When comparing brown trout biomass across 190 Norwegian lakes along a climate gradient, longer ice-covered duration decreased the biomass only in lakes where brown trout lived together with Arctic charr. We were not able to detect any effect of ice-cover on brown trout biomass in lakes where brown trout was the only fish species. 4. Similarly, a 25-year time series from a lake with both brown trout and Arctic charr showed that brown trout population growth rate depended on the interaction between ice breakup date and Arctic charr abundance. High charr abundance was correlated with low trout population growth rate only in combination with long winters. 5. In conclusion, the two species differed in performance under ice, and the observed outcome of competition in natural populations was strongly dependent on duration of the ice-covered period. Our study shows that changes in ice phenology may alter species interactions in Northern aquatic systems. Increased knowledge of how adaptations to winter conditions differ among coexisting species is therefore vital for our understanding of ecological impacts of climate change.
Ann file
T1 Species 528 539 brown trout
N1 Reference T1 Taxonomy:8032
T2 Species 541 553 Salmo trutta
N2 Reference T2 Taxonomy:8032
T3 Species 625 637 Arctic charr
N3 Reference T3 Taxonomy:8036
T4 Species 639 657 Salvelinus alpinus
N4 Reference T4 Taxonomy:8036
T5 Species 787 798 brown trout
N5 Reference T5 Taxonomy:8032
T6 Species 820 832 Arctic charr
N6 Reference T6 Taxonomy:8036
T7 Species 837 848 brown trout
N7 Reference T7 Taxonomy:8032
T8 Species 995 1006 brown trout
N8 Reference T8 Taxonomy:8032
T9 Species 1008 1020 Arctic charr
N9 Reference T9 Taxonomy:8036
T10 Species 1125 1136 brown trout
N10 Reference T10 Taxonomy:8032
T11 Species 1138 1150 Arctic charr
N11 Reference T11 Taxonomy:8036
T12 Species 1293 1304 brown trout
N12 Reference T12 Taxonomy:8032
T13 Species 1436 1447 brown trout
N13 Reference T13 Taxonomy:8032
T14 Species 1468 1480 Arctic charr
N14 Reference T14 Taxonomy:8036
T15 Species 1536 1547 brown trout
N15 Reference T15 Taxonomy:8032
T16 Species 1571 1582 brown trout
N16 Reference T16 Taxonomy:8032
T17 Species 1668 1679 brown trout
N17 Reference T17 Taxonomy:8032
T18 Species 1684 1696 Arctic charr
N18 Reference T18 Taxonomy:8036
T19 Species 1709 1720 brown trout
N19 Reference T19 Taxonomy:8032
T20 Species 1801 1813 Arctic charr
N20 Reference T20 Taxonomy:8036
T21 Species 1830 1835 charr
N21 Reference T21 Taxonomy:8036
T22 Species 1870 1875 trout
N22 Reference T22 Taxonomy:8032