Abstract
Perch Perca fluviatilis is a widespread predator in European reservoirs, frequent in open waters but also known to spend a lot of time in the littoral zones. To get insight into how adult perch used and selected their habitat in an environment subject to water-level (WL) fluctuations, 21 perch were continuously tracked using acoustic telemetry over 2 years in the Bariousses Reservoir (France). The different available habitats were characterized by depth classes and substrate types, presence of emerging trees and presence of tree stumps in the littoral zone. We showed that perch habitat preferences were strongly dependent on the season, except for substrate type, and in line with their habitat use. Surprisingly we did not find any influence of the WL which, however, reduced the structural complexity of the littoral zone when lowering. In spring and summer, whatever the WL, we observed a strong preference for the littoral zone and complex habitats. In autumn and winter, perch migrated into deeper waters. However, the individual variability of the habitat preferences was quite high. This type of research helps to understand the spatial ecology of fish and provides useful guidance to hydromorphological restoration for fish populations.
Highlights
Whatever their origin, lake littoral zones are transitional areas between terrestrial and aquatic habitats that generally host a high biodiversity (Schmieder, 2004)
Variability of habitat availability with water level (WL) Using a precise qualitative and quantitative description of the different habitats, we highlighted an influence of WL on the structure of the available littoral habitats of the Bariousses reservoir: they tended to become more homogeneous with a lowering structural complexity when the WL dropped
Influence of WL on habitat preference water level fluctuations (WLF) directly impacted the relative availability of the different littoral habitats; we did not observe any significant effect of WL on the habitat preference of adult perch
Summary
Lake littoral zones are transitional areas between terrestrial and aquatic habitats that generally host a high biodiversity (Schmieder, 2004). They provide resources available nowhere else in the lacustrine ecosystem (Zohary & Gasith, 2014) and most lake fishes use them during their life cycle (Winfield, 2004). WLF can lead to loss of potential prey (Winfield, 2004), loss of refuge areas (Kaczka & Miranda, 2014) and loss of spawning habitats (Hudon et al, 2005) for fish fauna.
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