The fatty acid composition of the leatherback turtle Dermochelys coriacea and its jellyfish prey

Abstract

The leatherback turtle, Dermochelys coriacea (L.) studied was a male, weighing 916 kg, with a total dorsal length of 291 cm. It was beached on the Welsh coast, UK in September 1988 and is currently the largest leatherback ever recorded.Total lipid formed between 87.5 and 95.4% of the dry weight of representative samples of the blubber and 43.0% and 4.9% of the liver and pectoral muscle respectively. High levels of neutral lipid in the liver (79.0% of the total lipid) as well as the blubber (87.6–99.9% of the total lipid) suggest an important energy storage function for these tissues.Overall, with the notable exception of 22:lwll, fatty acids which are found in a putative jellyfish diet of Rhizostoma, Amelia, Cyanea and Chrysaora are also present in the leatherback liver and muscle, blubber and other fatty tissues. Fatty acid 22:lwll is present in the jellyfish samples, but is absent or at trace levels only in the leatherback tissues (0.1–0.3% of the total fatty acids).The polyunsaturated fatty acids of the w3 series 20:5w3, 22:5w3 and 22:6w3 are well represented in leatherback adipose tissues, muscle and liver as well as in the jellyfish examined. The leatherback and jellyfish lipids are therefore marine in character, but are also similar to terrestrial animal lipid in having a high proportion of fatty acids of the w6 series, principally arachidonic acid, 20:4w6. The significant levels of 20:4w6 in jellyfish total lipid (9.7–20.0% of the total fatty acids) and in the leatherback neutral lipid (1.0–10.9% of the total fatty acids) and phospholipid (0.6–15.5% of total fatty acids) fractions of all tissues sampled suggests that arachidonic acid assumes more importance in food chain relationships involving leatherbacks than in other marine food webs such as those involving fish.