Meeting Abstract
71.3 Thursday, Jan. 6 Depth-specific fatty acid composition and temperature dependent thermal properties of the blubber of short-finned pilot whales (Globicephala macrorhynchus) BAGGE, L.E.*; KOOPMAN, H.N; POKORNY, A.; MCLELLAN, W.A.; PABST, D.A.; Univ. of North Carolina Wilmington leb3576@uncw.edu
Blubber, the specialized hypodermis of cetaceans, stores lipids and provides thermal insulation. Blubber is stratified across its depth, but how blubber’s stratified lipid content and fatty acid (FA) composition affect its depth-specific thermal properties has not yet been investigated. We utilized samples from short-finned pilot whales (Globicephala macrorhynchus) to measure the thermal properties of the integument (epidermis and blubber) of adult females (n=12). The thermal conductivities (Wm-1°C-1) of the deep, middle, and superficial layers of blubber were measured using the standard material method. Although the deep and middle blubber layers possessed more lipid, their conductivity values were unexpectedly higher than those of superficial blubber. Factors influencing the complex thermal properties of blubber across layers may include (a) FA compositional differences (chain length and degree of unsaturation can affect conductivity) and/or (b) blubber’s ability to store heat by undergoing temperature dependent phase change. Gas chromatography analyses demonstrated that the deep layer contains more long chain, polyunsaturated FA than the superficial layer. To better understand how this composition affects blubber’s heat storing capacity, we are investigating the phase change behavior of blubber’s constituent lipids using differential scanning calorimetry. Preliminary results show that blubber lipids undergo a broad phase transition within the range of physiologically relevant temperatures. These results suggest that blubber’s function as an insulator is complex and may rely upon its stratified composition and dynamic heat storage capabilities.
