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Blubber deposition during ontogeny in free‐ranging bottlenose dolphins (Tursiops truncatus): balancing disparate roles of insulation and locomotion
Author(s) -
Noren Shawn Ranee,
Wells Randall S.
Publication year - 2009
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.23.1_supplement.598.12
Subject(s) - blubber , thermoregulation , buoyancy , deposition (geology) , neutral buoyancy , bay , biology , ontogeny , zoology , environmental science , ecology , fishery , oceanography , geology , physics , paleontology , genetics , quantum mechanics , sediment
Water conducts heat 25 times faster than air creating an extreme environment for mammalian thermoregulation. Blubber is a key component of dolphin thermoregulation but the cost of descent (COD) to overcome blubber's buoyant force while diving could constrain its deposition. This conflict was examined in 1‐12 year‐old bottlenose dolphins in Sarasota Bay, Florida in summer (mean water temperature: 29.7 ± 0.1 °C) and winter (mean water temperature: 19.2 ± 0.4 °C). Surface area to volume ratio decreased significantly with age. Yearlings had significantly thicker blubber than 2‐12 year‐olds during summer, but this difference diminished by winter as blubber deposition in response to colder water temperature was smaller in yearlings (2 mm increase) compared to 2‐12 year‐olds (3‐6 mm increase). This disparity may be explained by the buoyant force of blubber and the associated locomotor costs to overcome buoyancy while diving. During summer, calculated buoyancy was highest in yearlings, 6.24 ± 0.41 N compared to ‐0.98 ± 0.90 N (neutrally buoyant) for 12 year‐olds. Conversely, all dolphins converged upon a similar buoyant force in winter (8.01 ± 0.56 N). As a result, the calculated mass‐specific COD to overcome buoyancy on a 10 m dive was greatest in yearlings. Balancing energetic demands of locomotion and thermoregulation may limit the flexibility of yearlings to adjust blubber in response to fluctuating water temperatures.