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Ice-cover effects on competitive interactions between two fish species
Ingeborg P Helland1, Anders G Finstad, Torbjørn Forseth
1Norwegian Institute for Nature Research, PO Box 5685, Sluppen, NO-7485 Trondheim, Norway. ingeborg.helland@nina.no
The Journal of Animal Ecology
|January 5, 2011
Summary
Winter ice cover duration significantly impacts fish competition. Arctic charr thrives in darkness, outcompeting brown trout during longer winters, affecting trout populations in northern freshwater ecosystems.
Area of Science:
- Ecology
- Climate Change Biology
- Freshwater Ecology
Background:
- Seasonal variations in ecological interactions, especially winter conditions, are understudied.
- Climate change is altering ecosystems, necessitating research into seasonal ecological dynamics.
- Winter in northern temperate freshwaters presents challenges like low temperatures, reduced food, and darkness due to ice cover.
Purpose of the Study:
- To investigate how brown trout (Salmo trutta) respond to varying ice-cover duration and competition with Arctic charr (Salvelinus alpinus).
- To link laboratory-derived physiological performance with field data on brown trout abundance.
- To understand the ecological impacts of changing ice phenology on freshwater fish interactions.
Main Methods:
- Laboratory experiments simulating ice-cover (darkness) versus daylight conditions to measure metabolic rates and growth.
- Semi-natural environment experiments with natural food supply to assess species performance.
- Field studies across 190 Norwegian lakes to correlate brown trout biomass with ice-cover duration and Arctic charr presence.
- Analysis of a 25-year time series data to examine brown trout population growth in relation to ice breakup date and Arctic charr abundance.
Main Results:
- Both species reduced metabolic rates in darkness, but Arctic charr maintained positive growth and had higher food intake than brown trout.
- Arctic charr exhibited better energy utilization (lower energy loss) under simulated ice-cover in semi-natural conditions.
- Increased ice-cover duration negatively impacted brown trout biomass only in lakes shared with Arctic charr.
- Brown trout population growth rate was negatively affected by long winters only when Arctic charr was abundant.
Conclusions:
- Species-specific physiological differences in winter performance influence competitive outcomes.
- The duration of ice cover is a critical factor modulating the strength of interspecific competition between brown trout and Arctic charr.
- Changes in ice phenology due to climate change can significantly alter species interactions and community structure in northern aquatic ecosystems.
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