Topographical variation in lipid content and morphological structure of the blubber in the striped dolphin

• Published in: Scientia marina 2015-06, Vol.79 (2), p.189-197
• Main Authors: Gómez-Campos, Encarna, Borrell, Asunción, Correas, Jordi, Aguilar, Alex
• Format: Article
• Language: English
• Subjects: adipocytes; Cetacea; cetacean; Cetacis; Dofins; Dolphins; Histologia; Histology; lipid content; Morfologia (Biologia); Morphology (Biology); Stenella coeruleoalba; stratification
• ISSN: 0214-8358; 1886-8134
• DOI: 10.3989/scimar.04093.25A

We investigate stratification patterns and topographical variations in the blubber of the striped dolphin (Stenella coeruleoalba) to gain insights into its regionally-specific functions. We collected blubber from 10 stranded striped dolphins (5 females and 5 males) from the eastern coast of Spain in 2007-2009, at 11 body positions. Histological measurements (adipocyte number and area) and blubber lipid content were analysed for each position. Histological measurements revealed stratification of blubber into outer, middle, and inner layers. Both the adipocyte number and area were largest in the middle layer. The adipocyte number was higher in the outer than the inner layer, whereas the adipocyte area was higher in the inner than the outer layer. The ventral anterior position did not follow this pattern, likely due to its proximity to the acoustic blubber, which is known to have a different biochemical composition. The stratification in morphological blubber characteristics most likely reflects functional differences. The outer layer may provide structural support and act as a mechanical barrier with a minor role in energy storage. The middle layer may be responsible for thermoregulation, and the inner layer could be responsible for energy mobilization, which is favoured by its proximity to the body core and a higher vascularization. In addition, an increasing gradient from dorsal to ventral positions was observed in the mean number of adipocytes and lipid content, with the exception of the caudal region. Although both ventral and dorsal blubber can have insulator and buoyancy functions, the ventral blubber may mainly serve as an energy reserve.Original Abstract: En el presente estudio se investigaron los patrones de estratificacion asi como las variaciones topograficas en la grasa del delfin listado (Stenella coeruleoalba) con el fin de conocer mejor las posibles funciones regionales de este tejido. Se recolectaron muestras de grasa en 11 posiciones corporales diferentes de 10 delfines listados (5 hembras y 5 machos) varados en la costa este de Espana entre los anos 2007 y 2009. Las medidas histologicas (numero de adipocitos y area de los mismos) y el contenido lipidico se analizaron en cada una de las posiciones. Las medidas histologicas mostraron que la grasa se estratificaba en 3 capas: externa, media e interna. Tanto el numero de adipocitos como su area eran mayores en la capa media. El numero de adipocitos era superior en la capa externa que en la inte