title: Circadian behaviour of Tectus (Trochus) niloticus in the southwest Pacific inferred from accelerometry.
abstract: BACKGROUND
  Behaviour and time spent active and inactive are key factors in animal ecology, with important consequences for bioenergetics. For the first time, here, we equipped the gastropod Tectus (= Trochus) niloticus with accelerometers to describe activity rhythms at two sites in the Southwest Pacific with different temperature regimes: New Caledonia and Vanuatu.
  
  
  RESULTS
  Based on a 24-hour cycle, T. niloticus activity began at dusk and gradually stopped during the night, before sunrise. This nocturnal behaviour was characterised by short (duration <30 s), low intensity (acceleration < 0.12 ɡ) movements and was probably associated with foraging behaviour. We assumed that activity ceased once the animal was satiated. Our analysis of two size groups in Vanuatu (80-90 mm vs. 120-140 mm, basal shell diameter) revealed a size effect; smaller specimens displayed greater activity, reflected by more intense and longer movements while migrating at night toward the edge of the reef. This nocturnal behaviour is not uncommon for grazing gastropods and is mainly associated with attempting to avoid visual predators whilst feeding.
  
  
  CONCLUSIONS
  The use of accelerometers coupled with light and temperature sensors provided detailed information on topshell behaviour and physiology under natural conditions. These data provide a foundation for identifying potential changes in the fine-scale behaviour of T. niloticus in response to environmental changes, which is essential in animal ecology and stock conservation.
authors.affiliation: Institut Universitaire Européen de la Mer (UMR CNRS 6539), Université de Bretagne Occidentale, rue Dumont d'Urville, F-29280 Plouzané, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Jolivet
authors.affiliation: Institut Universitaire Européen de la Mer (UMR CNRS 6539), Université de Bretagne Occidentale, rue Dumont d'Urville, F-29280 Plouzané, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Chauvaud
authors.affiliation: Institut Universitaire Européen de la Mer (UMR CNRS 6539), Université de Bretagne Occidentale, rue Dumont d'Urville, F-29280 Plouzané, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Thébault
authors.affiliation: LabexMER, UMS 3113 CNRS, Institut Universitaire Européen de la Mer, Université de Brest, Rue Dumont D'Urville, 29280 Plouzané, France ; Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8564 Japan.
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Robson
authors.affiliation: Institut de Recherche pour le Développement (UR 227 CoReUs), 2, Fisheries Department of Vanuatu, Port-Vila, Vanuatu.
authors.forename: Pascal
authors.initials: P
authors.lastname: Dumas
authors.affiliation: SANMA Fisheries Department of Vanuatu, Port-Vila, Vanuatu.
authors.forename: George
authors.initials: G
authors.lastname: Amos
authors.affiliation: Institut de Recherche pour le Développement (UMR 6539 CNRS/UBO/IRD/IFREMER), BPA5, 98848 Nouméa cedex, Nouvelle Calédonie.
authors.forename: Anne
authors.initials: A
authors.lastname: Lorrain
keywords: 24-hour periodicity; Accelerometry; Activity; Foraging; Migration; Tectus niloticus