title: Predicting cetacean habitats from their energetic needs and the distribution of their prey in two contrasted tropical regions.
abstract: To date, most habitat models of cetaceans have relied on static and oceanographic covariates, and very few have related cetaceans directly to the distribution of their prey, as a result of the limited availability of prey data. By simulating the distribution of six functional micronekton groups between the surface and ≃1,000 m deep, the SEAPODYM model provides valuable insights into prey distributions. We used SEAPODYM outputs to investigate the habitat of three cetacean guilds with increasing energy requirements: sperm and beaked whales, Globicephalinae and Delphininae. We expected High Energy Requirements cetaceans to preferentially forage in habitats of high prey biomass and/or production, where they might easily meet their high energetic needs, and Low Energy Requirements cetaceans to forage in habitats of either high or low prey biomass and/or production. Cetacean sightings were collected from dedicated aerial surveys in the South West Indian Ocean (SWIO) and French Polynesia (FP). We examined cetacean densities in relation to simulated distributions of their potential prey using Generalised Additive Models and predicted their habitats in both regions. Results supported their known diving abilities, with Delphininae mostly related to prey present in the upper layers of the water column, and Globicephalinae and sperm and beaked whales also related to prey present in deeper layers. Explained deviances ranged from 9% for sperm and beaked whales in the SWIO to 47% for Globicephalinae in FP. Delphininae and Globicephalinae appeared to select areas where high prey biomass and/or production were available at shallow depths. In contrast, sperm and beaked whales showed less clear habitat selection. Using simulated prey distributions as predictors in cetacean habitat models is crucial to understand their strategies of habitat selection in the three dimensions of the ocean.
authors.affiliation: Centre d'Études Biologiques de Chizé-La Rochelle, UMR 7372 Université de La Rochelle - CNRS, Institut du Littoral et de l'Environnement, La Rochelle, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Lambert
authors.affiliation: Marine Geospatial Ecology Lab, Duke University West Campus, Durham, North Carolina, United States of America.
authors.forename: Laura
authors.initials: L
authors.lastname: Mannocci
authors.affiliation: MEMMS (Marine Ecosystems Modeling and Monitoring by Satellites), CLS, Space Oceanography Division, Ramonville, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Lehodey
authors.affiliation: Centre d'Études Biologiques de Chizé-La Rochelle, UMR 7372 Université de La Rochelle - CNRS, Institut du Littoral et de l'Environnement, La Rochelle, France; Observatoire PELAGIS, UMS 3462 Université de La Rochelle - CNRS, Systèmes d'Observation pour la Conservation des Mammifères et des Oiseaux Marins, La Rochelle, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Ridoux
mesh_terms: D063147:Animal Distribution / Q000502:physiology*; D025041:Animal Migration / Q000502:physiology; D000818:Animals; D002591:Cetacea / Q000502:physiology*; D004455:Echolocation / Q000502:physiology; D017753:Ecosystem; D004734:Energy Metabolism / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology; D020387:Food Chain; D019156:Indian Ocean; D015233:Models, Statistical; D011114:Polynesia; D011235:Predatory Behavior / Q000502:physiology; D013045:Species Specificity; D050661:Sperm Whale / Q000502:physiology*; D014907:Whales / Q000502:physiology*; D050686:Whales, Pilot / Q000502:physiology*