Spatiotemporal dynamics of brown trout populations in natural and bypassed reaches

Autor: Bret, Victor
Přispěvatelé: Milieux aquatiques, écologie et pollutions (UR MALY), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Université de Lyon, Hervé Capra, Véronique Gouraud
Jazyk: francouzština
Rok vydání: 2016
Předmět:
Zdroj: Zootechnie. Université de Lyon, 2016. Français. ⟨NNT : 2016LYSE1051⟩
Popis: Brown trout (Salmo trutta) ecology was largely studied. However, the process structuring the spatiotemporal patterns of population dynamics remains unclear. The objective of this thesis was to identify the demographic processes (e.g. survival or displacements) and the influence of biotic (between-individuals interactions) and abiotic (environmental conditions) processes structuring the age-stages (fry, juveniles and adults) of these populations in time and space.I studied (1) the role of density-dependence on survival and (2) the influence of environmental conditions experienced by trouts (hydraulics and water temperature). To assess the results’ transferability, I studied (3) the spatial scale (global or local) of influence of the processes and (4) if those processes varied among populations (hierarchical approach).I considered the dynamics of 45 trout populations, 22 being located downstream a hydropower facility. At a large scale, the recruitment of distant populations (up to 75 km apart) may be synchronized by large floods during emergence of fry or by spawning substratum displacements. We summarized the results of a determinist population dynamics models, locally calibrated on nine reaches showing well-described environmental conditions. This summary revealed the influence of various local drivers on population dynamics. Finally, a hierarchical model showed that density-dependent mortality among juveniles and adults was a key biotic process. The strength of the competition was greater in absence of shelter (
Databáze: OpenAIRE
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