Diel activity and foraging mode of juvenile Arctic charr in fluctuating water flow - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Journal Articles River Research and Applications Year : 2018

Diel activity and foraging mode of juvenile Arctic charr in fluctuating water flow

Abstract

Streams fluctuate in water flow because of natural (e.g., rain) and human‐induced events (e.g., hydropeaking). Magnitude, frequency, and predictability of these events can have drastic consequences for fish populations. We studied how rapid modifications of water flow affect diel activity and foraging mode of juvenile Arctic charr Salvelinus alpinus in stream enclosures exposed to either stable (intermediate) or fluctuating (low vs. high) water flow. Under stable conditions, Arctic charr showed limited activity (9.4%). In fluctuating water flow, charr increased activity during low flow periods, especially during the first hours after the flow decreased, but ceased activity almost completely at high flow. Charr were mostly nocturnal, and more nocturnal at low than intermediate water flow. Fish were more mobile and swam faster during prey search and attacked prey at longer distances at low water flow. Activity and foraging mode differed between the first and second day after reduced water flow, suggesting that Arctic charr require time to adjust their foraging behaviour. This study demonstrates the importance of behavioural flexibility for population ecology in fluctuating environments such as regulated rivers.

Dates and versions

hal-04440910 , version 1 (06-02-2024)

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Nicolas Larranaga, S.K. Valdimarsson, T. Linnansaari, S.Ó. Steingrímsson. Diel activity and foraging mode of juvenile Arctic charr in fluctuating water flow. River Research and Applications, 2018, 34 (4), pp.348-356. ⟨10.1002/rra.3256⟩. ⟨hal-04440910⟩

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