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Blubber morphology in wild bottlenose dolphins ( Tursiops truncatus ) from the Southeastern United States: Influence of geographic location, age class, and reproductive state
Author(s) -
Montie Eric W.,
Garvin Scott R.,
Fair Patricia A.,
Bossart Gregory D.,
Mitchum Greg B.,
McFee Wayne E.,
Speakman Todd,
Starczak Victoria R.,
Hahn Mark E.
Publication year - 2008
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.10602
Subject(s) - blubber , biology , bottlenose dolphin , zoology , predation , reproduction , ecology
This study investigated blubber morphology and correlations of histological measurements with ontogeny, geography, and reproductive state in live, wild bottlenose dolphins ( Tursiops truncatus ) from the southeastern United States. Surgical skin‐blubber biopsies ( N = 74) were collected from dolphins during capture–release studies conducted in two geographic locations: Charleston, SC ( N = 38) and Indian River Lagoon, FL ( N = 36). Histological analysis of blubber revealed stratification into superficial, middle, and deep layers. Adipocytes of the middle blubber were 1.6× larger in Charleston subadults than in Indian River Lagoon subadults (4,590 ± 340 compared to 2,833 ± 335 μm 2 per cell). Charleston subadult dolphins contained higher levels of total blubber lipids than Charleston adult animals (49.3% ± 1.9% compared to 34.2% ± 1.7%), and this difference was manifested in more adipocytes in the middle blubber layer (19.2 ± 0.9 compared to 14.9 ± 0.5 cells per field). However, dolphins from Indian River Lagoon did not exhibit this pattern, and the adipocyte cell counts of subadults were approximately equal to those of the adults (16.0 ± 1.4 compared to 13.4 ± 0.8 cells per field). The colder year‐round water temperatures in Charleston compared to Indian River Lagoon may explain these differences. Adipocytes in the deep blubber layer were significantly smaller in lactating and simultaneously pregnant and lactating animals compared to pregnant dolphins (840 ± 179, 627 ± 333, and 2,776 ± 586 μm 2 per cell, respectively). Total blubber lipid content and adipocyte size in the deep blubber of mothers with calves decreased linearly with calf length. Lactating females may utilize lipids from the deep blubber during periods of increased energetic demands associated with offspring care. This study demonstrates that ontogeny, geography, and reproductive state may influence morphological parameters such as structural fiber densities and adipocyte numbers and sizes, measured in bottlenose dolphin blubber. J. Morphol. 269:496–511, 2008. © 2007 Wiley‐Liss, Inc.