Isotopic tissue fractionation in captive and wild lobsters Palinurus elephas (Fabricius, 1787)

Abstract

Isotopic fractionation δ13C and for δ15N of the spiny lobster Palinurus elephas has been tested in four tissues: tail and leg muscle, telson and hemolymph. Comparison of tissue fractionation factors among tissues in two groups of lobsters, captive (controlled diet) and wild, show lower intra-individual variability in captive than in wild individuals. Statistical analysis (PERMANOVA) was performed to check for significant differences in δ13C and δ15N isotopic signatures between tissues and treatments. Results show significant differences in the δ13C and δ15N isotopic composition among the four tissues analyzed. Legs are the most enriched tissue in δ15N, followed by muscle, hemolymph and telson in both captive and wild specimens. For δ13C the sequence is muscle > legs> hemolymph ~ telson. The fractionation or enrichment factor for δ 13C is 0.87‰ and 1.17‰ and for δ15N 1.99‰ and 2.38‰, in captive and wild lobsters respectively. Leg muscle presents the lowest variability at isotopic level for N and telson for C. Telson presents differences for N and C in both captive and wild lobsters (Mann-U Whitney p<0.05). Hemolymph and leg only present statistical differences for N between captive and wild individuals. In the first study of tissue isotopic fractioning of a spiny lobster species we conclude that leg muscle is the best tissue for studying P. elephas trophic dynamics applying non-invasive techniques