Structure of a toothed cetacean community around a tropical island (Mayotte, Mozambique Channel)

  • J Kiszka
  • PJ Ersts
  • V Ridoux

Abstract

We describe the structure of a toothed cetacean community around the island of Mayotte (South-West Indian Ocean, 45°10′ E, 12°50′ S), using data collected from small boat-based surveys conducted between July 2004 and June 2006. In all, 16 odontocete species were recorded. Diversity (Shannon-Weaver index) was particularly high along the outer slope of the barrier reef. Patterns of spatial distribution underscore the existence of three main cetacean habitat types: the inner lagoon (Indo-Pacific bottlenosed dolphin Tursiops aduncus and humpback dolphin Sousa chinensis), the outer-reef slope (spinner dolphin Stenella longirostris, pantropical spotted dolphin S. attenuate and melon-headed whale Peponocephala electra) and oceanic waters deeper than 500 m (e.g. Blainville’s beaked whale Mesoplodon densirostris). Group characteristics were highly variable among species, with oceanic small delphinids characterised by larger group sizes than strictly coastal and non-delphinid oceanic species. The outer slope of the barrier reef appears to be of primary importance in terms of density and diversity of odontocetes around Mayotte. Results support the hypothesis that a number of cetacean species, particularly several delphinid species, are dependent on coral reef complexes.

Keywords: barrier reef slope, cetaceans, community composition, distribution, encounter rates, Indian Ocean, Mayotte, odontocetes

African Journal of Marine Science 2010, 32(3): 543–551

Author Biographies

J Kiszka
Observatoire des Mammifères Marins, Direction de l’Agriculture et de la Forêt & Office National de la Chasse et de la Faune Sauvage, BP 103, 97600 Mamoudzou, Mayotte; current address: LIttoral, ENvironnement et Sociétés (LIENSs), UMR 6250, CNRS-Université de La Rochelle, 2, rue Olympe de Gouges, F-17000, La Rochelle, France; Direction de l’Environnement et du Développement Durable, Collectivité Départementale de Mayotte, BP 101 F-97600 Mamoudzou, Mayotte
PJ Ersts
Center for Biodiversity and Conservation, American Museum of Natural History, Central Park West at 79th Street, New York, 10024 USA
V Ridoux
Observatoire des Mammifères Marins, Direction de l’Agriculture et de la Forêt & Office National de la Chasse et de la Faune Sauvage, BP 103, 97600 Mamoudzou, Mayotte; current address: LIttoral, ENvironnement et Sociétés (LIENSs), UMR 6250, CNRS-Université de La Rochelle, 2, rue Olympe de Gouges, F-17000, La Rochelle, France
Section
Articles

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eISSN: 1814-2338
print ISSN: 1814-232X