Anatomical distribution of lipids and their fatty acids in the semipalmated sandpiper Calidris pusilla L. from Shepody Bay, New Brunswick, Canada

Abstract

Lipids have been analyzed in several tissues of the semipalmated sandpiper Calidris pusilla L. from eastern Canada. Specimens of this migratory shorebird were captured in July and August 1986. Large lipid stores were observed not only in subdermal fat, but in all the tissues examined. Total lipid content was very variable, ranging from 20.5 to 41% of the wet weight. A very high lipid content was found associated with the empty digestive tract of both lean and fat birds. Triacylglycerols were the dominant lipid class in all tissues analyzed; they accounted for 49% of the total lipids in liver, 60% in pectoral muscle, 81% in the digestive tract, 90% in the carcasses and 95% in adipose tissue. Squalene, apparently endogenous, was the only hydrocarbon detected. The contents of this isoprenoid hydrocarbon in adipose tissue, carcass and feathers were 22.5; 510 and 880 μg·g −1 of lipid, respectively. The fatty acid compositions of the different semipalmated sandpiper tissues analyzed were very similar since the profiles were dominated by the triacylglycerol fatty acids. Total lipid fatty acids of all organs examined showed relatively high levels of conserved n-3-polyunsaturated fatty acids of dietary origin (≈20% of the total). High proportions of 18:0 and 18:1n-9, apparently freshly biosynthesized, completed a fatty acid composition which was intermediate between a marine and a terrestrial pattern.