Predicting Cetacean Habitats from Their Energetic Needs and the Distribution of Their Prey in Two Contrasted Tropical Regions

Charlotte Lambert (1) , Laura Mannocci (2) , Patrick Lehodey (3) , Vincent Ridoux (2)

1 CEBC - Centre d'Études Biologiques de Chizé - UMR 7372
2 LIENSs - LIttoral ENvironnement et Sociétés
3 MEMMS - Marine Ecosystems Modeling and Monitoring by Satellites

To date, most habitat models of cetaceans have relied on static and oceanographic covariates, and very few have relatedcetaceans directly to the distribution of their prey, as a result of the limited availability of prey data. By simulating thedistribution of six functional micronekton groups between the surface and .1,000 m deep, the SEAPODYM model providesvaluable insights into prey distributions. We used SEAPODYM outputs to investigate the habitat of three cetacean guildswith increasing energy requirements: sperm and beaked whales, Globicephalinae and Delphininae. We expected HighEnergy Requirements cetaceans to preferentially forage in habitats of high prey biomass and/or production, where theymight easily meet their high energetic needs, and Low Energy Requirements cetaceans to forage in habitats of either highor low prey biomass and/or production. Cetacean sightings were collected from dedicated aerial surveys in the South WestIndian Ocean (SWIO) and French Polynesia (FP). We examined cetacean densities in relation to simulated distributions oftheir potential prey using Generalised Additive Models and predicted their habitats in both regions. Results supported theirknown diving abilities, with Delphininae mostly related to prey present in the upper layers of the water column, andGlobicephalinae and sperm and beaked whales also related to prey present in deeper layers. Explained deviances rangedfrom 9% for sperm and beaked whales in the SWIO to 47% for Globicephalinae in FP. Delphininae and Globicephalinaeappeared to select areas where high prey biomass and/or production were available at shallow depths. In contrast, spermand beaked whales showed less clear habitat selection. Using simulated prey distributions as predictors in cetacean habitatmodels is crucial to understand their strategies of habitat selection in the three dimensions of the ocean.

Domaines: Biodiversité et Ecologie; Océanographie; Zoologie des vertébrés

Charlotte Lambert, Laura Mannocci, Patrick Lehodey, Vincent Ridoux. Predicting Cetacean Habitats from Their Energetic Needs and the Distribution of Their Prey in Two Contrasted Tropical Regions. PLoS ONE, 2014, 9 (8), pp.e105958. ⟨10.1371/journal.pone.0105958⟩. ⟨hal-01075743⟩