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Marine Ecology Progress Series

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MEPS 305:101-111 (2005)  -  doi:10.3354/meps305101

Gonad fatty acids and trophic interactions of the echinoid Psammechinus miliaris

Adam D. Hughes1,*, Ana I. Catarino1,2, Maeve S. Kelly1, David K. A. Barnes3, Kenneth D. Black1

1Scottish Association for Marine Science, Dunbeg, Oban, Argyll PA37 1QA, UK
2Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1149-016 Lisboa, Portugal
3Biological Sciences Division, British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK

ABSTRACT: Variation in gonadal somatic indices (GSI) and fatty acid signatures of 2 contrasting Scottish west coast populations of the echinoid Psammechinus miliaris were examined. P. miliaris was sampled from both the shallow subtidal and at the upper limit of its distribution in the intertidal. The intertidal population had a significantly higher GSI than the subtidal at both locations. Multivariate analysis (ANOSIM) of the fatty acid signature showed significant variation between the 2 depths as well as between sex and location. SIMPER analysis indicated a complex pattern of variation between location and depths. Both 20:4(n-6) and 20:5(n-6), associated with brown algae, were found in higher levels in subtidal populations, while levels of 22:6(n-3) were higher in the intertidal at one site, and 18:4(n-3) higher at the other. Of these acids, 22:6(n-3) is associated with filter feeding invertebrates, and 18:4(n-3) with green algae. Omnivorous diets in urchins have been associated with increased gonadal growth and the results from this study strongly suggest that the observed differences in GSI between intertidal and subtidal P. miliaris result from a higher quality diet in the intertidal, consisting of invertebrates and green algae.

KEY WORDS: Sea urchin · Fatty acid · Gonadal somatic indices · Psammechinus miliaris · Diet

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