title: Energy expenditure of freely swimming adult green turtles (Chelonia mydas) and its link with body acceleration.
abstract: Marine turtles are globally threatened. Crucial for the conservation of these large ectotherms is a detailed knowledge of their energy relationships, especially their at-sea metabolic rates, which will ultimately define population structure and size. Measuring metabolic rates in free-ranging aquatic animals, however, remains a challenge. Hence, it is not surprising that for most marine turtle species we know little about the energetic requirements of adults at sea. Recently, accelerometry has emerged as a promising tool for estimating activity-specific metabolic rates of animals in the field. Accelerometry allows quantification of the movement of animals (ODBA/PDBA, overall/partial dynamic body acceleration), which, after calibration, might serve as a proxy for metabolic rate. We measured oxygen consumption rates (V(O(2))) of adult green turtles (Chelonia mydas; 142.1±26.9 kg) at rest and when swimming within a 13 m-long swim channel, using flow-through respirometry. We investigated the effect of water temperature (T(w)) on turtle and tested the hypothesis that turtle body acceleration can be used as a proxy for V(O(2)). Mean mass-specific V(O(2)) (sV(O(2))) of six turtles when resting at a T(w) of 25.8±1.0°C was 0.50±0.09 ml min(-1) kg(-0.83). sV(O(2))increased significantly with T(w) and activity level. Changes in sV(O(2)) were paralleled by changes in respiratory frequency (f(R)). Deploying bi-axial accelerometers in conjunction with respirometry, we found a significant positive relationship between sV(O(2)) and PDBA that was modified by T(w). The resulting predictive equation was highly significant (r(2)=0.83, P<0.0001) and associated error estimates were small (mean algebraic error 3.3%), indicating that body acceleration is a good predictor of V(O(2)) in green turtles. Our results suggest that accelerometry is a suitable method to investigate marine turtle energetics at sea.
authors.affiliation: Université de Strasbourg, IPHC, Strasbourg, France. manfred.enstipp@c-strasbourg.fr
authors.forename: Manfred R
authors.initials: MR
authors.lastname: Enstipp
authors.forename: Stéphane
authors.initials: S
authors.lastname: Ciccione
authors.forename: Benoit
authors.initials: B
authors.lastname: Gineste
authors.forename: Myriam
authors.initials: M
authors.lastname: Milbergue
authors.forename: Katia
authors.initials: K
authors.lastname: Ballorain
authors.forename: Yan
authors.initials: Y
authors.lastname: Ropert-Coudert
authors.forename: Akiko
authors.initials: A
authors.lastname: Kato
authors.forename: Virginie
authors.initials: V
authors.lastname: Plot
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Georges
mesh_terms: D000054:Acceleration; D000375:Aging / Q000502:physiology*; D000818:Animals; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D010101:Oxygen Consumption / Q000502:physiology; D015203:Reproducibility of Results; D012119:Respiration; D012621:Seasons; D013550:Swimming / Q000502:physiology*; D013696:Temperature; D014426:Turtles / Q000502:physiology*; D014867:Water
chemical_list: D014867:Water