Characterization and modeling of the vertical physical and biological habitat of deep-diving mammals

• Main Author: Tournier, Martin
• Other Authors: Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université de La Rochelle, Christophe Guinet, Mark Peter Johnson
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2022
• Subjects: Active acoustic; Sonar; Functional data analysis; Biologging; Mirounga leonina; Mesoplodon densirostris; Acoustique active; Analyses de données fonctionnelles; Bio-logging; [SDV.BA]Life Sciences [q-bio]/Animal biology; [SDV.SA]Life Sciences [q-bio]/Agricultural sciences; Elephant Seals; Southern Elephant Seals
• Online Access: https://theses.hal.science/tel-03962421; https://theses.hal.science/tel-03962421/document; https://theses.hal.science/tel-03962421/file/2022TOURNIER192188.pdf

Deep-diving mammals evolve within a tri-dimensional environment where the physical and biological conditions vary. These variations can influence their utilization of the vertical dimension. This Ph.D. thesis focuses, first, on acoustic signal analysis, the signal being sampled by a miniaturized echo-sounder deployed on southern elephant seals, and aims at biologically describing the water column. Through that acoustic signal, mid-trophic level organisms have been observed, as well as important particle export. Second, to determine the influence of dynamic environmental variables, such as temperature or salinity, on the vertical position of elephant seals and Blainville’s beaked whales, we proposed a new methodology suitable for using environmental predictors described in the form of profiles by using functional analysis approaches. When using the variables obtained in situ by elephant seals, we show that the environmental profiles influence the depth of the dives. However, the model tends to underestimate the predicted depth of animals, mainly in areas where high oceanic dynamics are observed. When using the same approach on the restricted beaked whales’ dataset, and by using environmental variables obtained from oceanographic models, we did not observe any impact of the environmental conditions on the whales’ water column use. This methodological approach could allow the integration of the vertical dimension toward the development of tri-dimensional habitat modelling under the conditions that the spatial and temporal resolutions of the dataset are adequate. Les mammifères marins grands plongeurs évoluent dans un environnement tridimensionnel dans lequel les conditions physiques et biologiques varient. Les variations de ces conditions peuvent influencer leur utilisation de la dimension verticale. Les travaux de cette thèse s’appuient dans un premier temps sur le traitement du signal acoustique échantillonné par un échosondeur miniaturisé déployé sur des éléphants de mer austraux, pour apporter une ...