Nocturnal light pollution impact on the oyster Crassostrea gigas : Study of the biological rhythm disruption and physiological consequences

• Main Author: Botté, Audrey
• Other Authors: Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-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), Université de Bordeaux, Damien Tran
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2023
• Subjects: Artificial Light at Night; Crassostrea gigas; Daily rhythm; Circadian clock; Behavior; Physiological processes; Lumière artificielle nocturne; Rythme journalier; Horloge circadienne; Comportement; Processus physiologiques; [SDV.BA.ZI]Life Sciences [q-bio]/Animal biology/Invertebrate Zoology
• Online Access: https://theses.hal.science/tel-04416121; https://theses.hal.science/tel-04416121/document; https://theses.hal.science/tel-04416121/file/BOTTE_AUDREY_2023.pdf

Artificial Light At Night (ALAN) masks natural light cycles used by organisms to synchronize their biological rhythm with the environment. By disrupting these rhythms, ALAN can have harmful physiological consequences. Coastal environments are largely affected by ALAN due to the high and growing human population density. However, despite this growing threat, ALAN effects on these ecosystems are poorly studied. The oyster Crassostrea gigas is a key species of these ecosystems likely exposed to ALAN. This work evaluates ALAN effects at low and realistic intensities on the oyster’s behavioral daily rhythm and on its internal clock according to its intensity, spectral composition and exposure modality. Furthermore, the impact of ALAN is also studied on the oyster’s shell growth and gill’s microbiota. Results show that ALAN affects the oyster behavioral daily rhythm and its molecular clock, suggesting a disruption of its functioning, strating from 0.1 lx with the strongest effects in blue light and the least strong in green light. In addition, this study suggests that cutting off direct lighting in the middle of the night but in the presence of skyglow could increase harmful effects. Finally, ALAN reduces shell growth and leads to dysbiosis of the gill’s microbiota. These adverse effects are directly correlated with the daily rhythm robustness. La lumière artificielle nocturne (LAN) masque les cycles naturels lumineux utilisés par les organismes pour synchroniser leurs rythmes biologiques avec l’environnement. En perturbant ces rythmes, LAN peut avoir de graves conséquences physiologiques. LAN touche fortement les environnements côtiers du fait de l’importante et croissante densité de population humaine. Cependant, malgré cette menace grandissante, les effets de LAN sur ces écosystèmes sont peu étudiés. L’huitre Crassostrea gigas est une espèce clé des environnements côtiers susceptible d’être exposée à LAN. Ce travail évalue les effets de LAN à des intensités faibles et realistes sur le rythme journalier ...