caa a22 4500 605514089 CHVBK 20210128100703.0 cr unu---uuuuu 210128e20151001xx s 000 0 eng 10.1007/s00360-015-0922-8 doi (NATIONALLICENCE)springer-10.1007/s00360-015-0922-8 Scaling matters: incorporating body composition into Weddell seal seasonal oxygen store comparisons reveals maintenance of aerobic capacities [Elektronische Daten] [Michelle Shero, Daniel Costa, Jennifer Burns] Adult Weddell seals (Leptonychotes weddellii) haul-out on the ice in October/November (austral spring) for the breeding season and reduce foraging activities for ~4months until their molt in the austral fall (January/February). After these periods, animals are at their leanest and resume actively foraging for the austral winter. In mammals, decreased exercise and hypoxia exposure typically lead to decreased production of O2-carrying proteins and muscle wasting, while endurance training increases aerobic potential. To test whether similar effects were present in marine mammals, this study compared the physiology of 53 post-molt female Weddell seals in the austral fall to 47 pre-breeding females during the spring in McMurdo Sound, Antarctica. Once body mass and condition (lipid) were controlled for, there were no seasonal changes in total body oxygen (TBO2) stores. Within each season, hematocrit and hemoglobin values were negatively correlated with animal size, and larger animals had lower mass-specific TBO2 stores. But because larger seals had lower mass-specific metabolic rates, their calculated aerobic dive limit was similar to smaller seals. Indicators of muscular efficiency, myosin heavy chain composition, myoglobin concentrations, and aerobic enzyme activities (citrate synthase and β-hydroxyacyl CoA dehydrogenase) were likewise maintained across the year. The preservation of aerobic capacity is likely critical to foraging capabilities, so that following the molt Weddell seals can rapidly regain body mass at the start of winter foraging. In contrast, muscle lactate dehydrogenase activity, a marker of anaerobic metabolism, exhibited seasonal plasticity in this diving top predator and was lowest after the summer period of reduced activity. Springer-Verlag Berlin Heidelberg, 2015 Aerobic dive limit nationallicence Body composition nationallicence Diving physiology nationallicence Enzymes nationallicence Myosin heavy chain nationallicence Oxygen stores nationallicence BV : Blood volume nationallicence (c)ADL : (Calculated) aerobic dive limit nationallicence CS : Citrate synthase (IUg wet tissue−1) nationallicence DMR : Diving metabolic rate nationallicence FOG : Fast-twitch oxidative glycolytic nationallicence Hb : Hemoglobin (gdL whole blood−1) nationallicence Hct : Hematocrit (% whole blood) nationallicence HOAD : β-Hydroxyacyl CoA dehydrogenase (IUg wet tissue−1) nationallicence LBM : Lean body mass (kg) nationallicence LD : Longissimus dorsi skeletal muscle nationallicence LDH : Lactate dehydrogenase (IUg wet tissue−1) nationallicence Mb : Myoglobin (mgg wet tissue−1) nationallicence MCHC : Mean corpuscular hemoglobin concentration (%) nationallicence MHC : Myosin heavy chain nationallicence PV : Plasma volume nationallicence RBC : Red blood cell (106μL whole blood−1) nationallicence SO : Slow-twitch oxidative nationallicence TBM : Total body mass (kg) nationallicence TBO2 : Total body oxygen stores nationallicence Shero Michelle Department of Biological Sciences, University of Alaska Anchorage, 99508, Anchorage, AK, USA aut Costa Daniel Department of Ecology and Evolutionary Biology, University of California Santa Cruz, 95060, Santa Cruz, CA, USA aut Burns Jennifer Department of Biological Sciences, University of Alaska Anchorage, 99508, Anchorage, AK, USA aut Journal of Comparative Physiology B Springer Berlin Heidelberg 185/7(2015-10-01), 811-824 0174-1578 185:7<811 2015 185 360 https://doi.org/10.1007/s00360-015-0922-8 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00360-015-0922-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Shero Michelle Department of Biological Sciences, University of Alaska Anchorage, 99508, Anchorage, AK, USA aut NATIONALLICENCE 700 1- Costa Daniel Department of Ecology and Evolutionary Biology, University of California Santa Cruz, 95060, Santa Cruz, CA, USA aut NATIONALLICENCE 700 1- Burns Jennifer Department of Biological Sciences, University of Alaska Anchorage, 99508, Anchorage, AK, USA aut NATIONALLICENCE 773 0- Journal of Comparative Physiology B Springer Berlin Heidelberg 185/7(2015-10-01), 811-824 0174-1578 185:7<811 2015 185 360