The impact of water obstacles on migrating young eels Anguilla anguilla

• Main Author: Podgorniak, Tomasz
• Other Authors: Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Ecosystèmes aquatiques et changements globaux (UR EABX), Université de Bordeaux, Françoise Daverat, Fabien Pierron, Eric De Oliveira
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2016
• Subjects: Dams; Behaviour; Transcription; Brain; Eel; Barrages; Comportement; Anguille; Cerveau; [SDV.EE]Life Sciences [q-bio]/Ecology; environment; Anguilla anguilla; European eel
• Online Access: https://tel.archives-ouvertes.fr/tel-01306573; https://tel.archives-ouvertes.fr/tel-01306573/document; https://tel.archives-ouvertes.fr/tel-01306573/file/PODGORNIAK_TOMASZ_2016_CORR.pdf

The European eel Anguilla anguilla is a catadromous fish with a large scale migration loop including the Sargasso sea, Europe and North Africa. In the last 30 years, drastic declines of abundance have been observed and the species is currently considered as critically endangered. One of the main causes of species decline is habitat fragmentation, which prevents migrating fish accessing growth zones.We studied whether aquatic obstacles can enact selectively on migrating young eels. We applied a no a priori approach to detect any traits involved in the process of obstacle passage. We used a microarray analysis for gene expression screening in three tissues (brain, liver, muscle) of young eels sampled in different sections of an impounded watercourse (article 1). The only differences detected between groups of fish concerned the brain tissue, and the detected genes were related to synaptic plasticity. We also found that transcription levels of genes related to neural activity, oestrogen and thyroid metabolisms were different after two months of common garden (article 2). Finally, we studied the relationship between the gene transcription and climbing behaviour (article 3). Upstream fish showed the highest climbing tendency. Moreover, we found that the ‘climbing’ leaders showed lower transcription levels of cognition-related gene than fish following them. We suggest that leaders can enact as bold and proactive individuals, in contrast to reactive followers.The implication of our results is discussed in an ecological context, where the presence of water obstacles can modify the distribution of different phenotypes in the upstream and downstream parts of the water axis. L’anguille européenne Anguilla anguilla est une espèce catadrome avec un cycle de vie complexe incluant des migrations entre la mer de Sargasses et l’Europe et l’Afrique du Nord. On a noté une baisse drastique de sa population depuis les 30 ans et on la considère aujourd’hui comme ‘en danger critique’. Une des causes principales de ce déclin est la ...