title: Regional variability in diving physiology and behavior in a widely distributed air-breathing marine predator, the South American sea lion (Otaria byronia).
abstract: Our understanding of how air-breathing marine predators cope with environmental variability is limited by our inadequate knowledge of their ecological and physiological parameters. Because of their wide distribution along both coasts of the sub-continent, South American sea lions (Otaria byronia) provide a valuable opportunity to study the behavioral and physiological plasticity of a marine predator in different environments. We measured the oxygen stores and diving behavior of South American sea lions throughout most of its range, allowing us to demonstrate that diving ability and behavior vary across its range. We found no significant differences in mass-specific blood volumes of sea lions among field sites and a negative relationship between mass-specific oxygen storage and size, which suggests that exposure to different habitats and geographical locations better explains oxygen storage capacities and diving capability in South American sea lions than body size alone. The largest animals in our study (individuals from Uruguay) were the shallowest and shortest duration divers, and had the lowest mass-specific total body oxygen stores, while the deepest and longest duration divers (individuals from southern Chile) had significantly larger mass-specific oxygen stores, despite being much smaller animals. Our study suggests that the physiology of air-breathing diving predators is not fixed, but that it can be adjusted, to a certain extent, depending on the ecological setting and or habitat. These adjustments can be thought of as a 'training effect': as the animal continues to push its physiological capacity through greater hypoxic exposure, its breath-holding capacity increases.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Long Marine Laboratory, 100 Shaffer Road, Santa Cruz, CA 95060, USA lahuckst@ucsc.edu.
authors.forename: Luis A
authors.identifier: 0000-0002-2453-7350
authors.initials: LA
authors.lastname: Hückstädt
authors.affiliation: Scripps Institution of Oceanography, University of California San Diego, Center for Marine Biodiversity and Biomedicine, 8655 Kennel Way, La Jolla, CA 92037, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Tift
authors.affiliation: Laboratorio de Ecologia Molecular de Vertebrados Acuaticos (LEMVA), Departamento de Ciencias Biologicas, Facultad de Ciencias, Universidad de Los Andes, Carrera 1E, #18A-10, Bogota, Colombia.
authors.forename: Federico
authors.initials: F
authors.lastname: Riet-Sapriza
authors.affiliation: Departamento de Ecología y Evolución Facultad de Ciencias, Universidad de la República, Iguá 4225 Esq. Mataojo C.P, 11400 Montevideo, Uruguay.
authors.forename: Valentina
authors.initials: V
authors.lastname: Franco-Trecu
authors.affiliation: South Atlantic Environmental Research Institute, Stanley FIQQ1ZZ, Falkland Islands School of Life and Environmental Sciences, Deakin University, Warrnambool Campus, Geelong, Australia.
authors.forename: Alastair M M
authors.initials: AM
authors.lastname: Baylis
authors.affiliation: Hatfield Marine Science Center, Oregon State University, 2030 SE Marine Science Drive, Newport, OR 97365, USA.
authors.forename: Rachael A
authors.initials: RA
authors.lastname: Orben
authors.affiliation: School of Life and Environmental Sciences, Deakin University, Burwood Campus, Geelong, Australia.
authors.forename: John P Y
authors.initials: JP
authors.lastname: Arnould
authors.affiliation: Centro de Investigación y Gestión en Recursos Naturales (CIGREN), Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Avenida Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile.
authors.forename: Maritza
authors.initials: M
authors.lastname: Sepulveda
authors.affiliation: Centro de Investigación y Gestión en Recursos Naturales (CIGREN), Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Avenida Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile.
authors.forename: Macarena
authors.initials: M
authors.lastname: Santos-Carvallo
authors.affiliation: Department of Biological Sciences, University of Alaska Anchorage. 3211 Providence Drive Anchorage, AK 99508, USA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Burns
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Long Marine Laboratory, 100 Shaffer Road, Santa Cruz, CA 95060, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Costa
mesh_terms: D000332:Aerobiosis; D000388:Air; D000818:Animals; D001835:Body Weight; D004242:Diving / Q000502:physiology*; D005843:Geography; D010100:Oxygen / Q000097:blood; D011235:Predatory Behavior / Q000502:physiology*; D012119:Respiration; D046070:Sea Lions / Q000502:physiology*; D013020:South America
chemical_list: D010100:Oxygen
keywords: Aerobic dive limit; Diving; Oxygen stores; Pinniped; South America