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The influence of buoyancy on diving metabolism of Steller sea lions (Eumetopias jubatus)
Author(s) -
Fahlman Andreas,
Hastie Gordon D.,
Rosen David A.S.,
Trites Andrew W
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a593-d
Subject(s) - sea lion , buoyancy , zoology , adipose tissue , biology , subcutaneous adipose tissue , chemistry , ecology , endocrinology , physics , quantum mechanics
Resting (RMR) and diving metabolic rates (DMR, l O 2 ·min −1 ) were measured in 3 female Steller sea lions (body masses, M b ): 135.0, 168.8 and 213.1 kg) in water with and without adjustment in buoyancy to determine if seasonal fluctuations in subcutaneous adipose tissue affect DMR. Total body water was used to assess percent body fat (body condition) and buoyancy for the control condition (B, range: −86N to −51N). Buoyancy was adjusted either positively (B+, range: −62N to −33 N) or negatively (B−, −101N to 64N) from the control condition to investigate the full range of body conditions experienced in the wild (12–27% body fat). Mean RMR ranged between 1.65 to 1.12 l O 2 · min −1 and was positively correlated with M b (P < 0.01). DMR was corrected for M b (sDMR) using a mass exponent of 0.6 (McPhee et al., J Exp Biol 2002). sDMR was found to decline exponentially with dive duration (DD, min), although significant differences were observed in slope and intercept (P < 0.01) between animals (r 2 = 0.51, ANCOVA). The best mixed model ANOVA, including animal as a random factor, was:s D M R = 0 . 130 ‐ 0 . 102 · [ 1 ‐e ( ‐ D D ) ]+ 6 . 48 · 10 ‐ 4 · D e p t hConsequently, sDMR was unaffected by changes in buoyancy but increased with depth and decreased with DD. (Support: North Pacific Marine Science Foundation and NOAA)