Changes in blubber distribution and morphology associated with starvation in the harbor porpoise (Phocoena phocoena): evidence for regional differences in blubber structure and function.

Published

Journal Article

To examine patterns of blubber loss accompanying a decline in body condition, blubber thickness of juvenile harbor porpoises in normal/robust body condition (n=69) was compared with that of starved conspecifics (n=31). Blubber thickness in the thorax of starved porpoises (9-11 mm) was only 50%-60% of that of normal animals (18-20 mm); however, very little tailstock blubber was lost during starvation. Adipocytes in thorax and tailstock blubber were measured in both groups (n=5) to determine whether thickness changes were homogeneous throughout blubber depth. In the thorax of normal porpoises, adipocytes near the epidermis (outer blubber) were smaller (0.11 nL) than inner blubber adipocytes (0.17 nL). Conversely, the size of tailstock adipocytes was uniform. Starved animals had fewer, smaller adipocytes in the inner thorax blubber, suggesting a possible combination of adipocyte shrinkage and loss. Lipids were withdrawn only from the inner layer of thorax blubber during starvation, supporting a hypothesis of regional specialization of function in blubber. Blubber of the thorax serves as the site of lipid deposition and mobilization, while the tailstock is metabolically inert and likely important in locomotion and streamlining. Therefore, some proportion of the blubber of small odontocetes must be considered structural/mechanical rather than an energy reserve.

Full Text

Duke Authors

Cited Authors

  • Koopman, HN; Pabst, DA; McLellan, WA; Dillaman, RM; Read, AJ

Published Date

  • September 2002

Published In

Volume / Issue

  • 75 / 5

Start / End Page

  • 498 - 512

PubMed ID

  • 12529851

Pubmed Central ID

  • 12529851

Electronic International Standard Serial Number (EISSN)

  • 1537-5293

International Standard Serial Number (ISSN)

  • 1522-2152

Digital Object Identifier (DOI)

  • 10.1086/342799

Language

  • eng