[en] Analyses of the natural abundance of carbon and nitrogen stable isotopes were performed to investigate the feeding habits of two ophiurolds, Ophiomastix venosa and Ophiocoma scolopendrina, and to assess the potential benefit obtained by the symbiotic Ophiomastix venosa juveniles. A tracer experiment was also carried Out to clarify the contribution of algae to the nitrogen uptake amongst the tested ophiurolds. Our results suggest that Ophiocoma scolopendrina adults occupy a higher position in the food web than Ophiomastix venosa and mainly feed on neuston. In contrast, O. venosa adults feed on the alga Sargassum densifolium, and on organic matter associated with sediment. Free juveniles and symbiotic juveniles of O. venosa have intermediate PC values between both adult species. The high proportion of C-13 in the symbiotic juveniles compared to the one in their conspecific adults indicates that their diet slightly differs from the latter and is closer to that of Ophiocoma scolopendrina. This raises the hypothesis that symbiotic juveniles steal neuston front their associated host, O. scolopendrina.
Research center :
MARE - Centre Interfacultaire de Recherches en Océanologie - ULiège
Disciplines :
Aquatic sciences & oceanology
Author, co-author :
Fourgon, Didier
Lepoint, Gilles ; Université de Liège - ULiège > Département des sciences et gestion de l'environnement > Océanologie
Eeckhaut, Igor
Language :
English
Title :
Assessment of trophic relationships between symbiotic tropical ophiuroids using C and N stable isotope analysis
Publication date :
December 2006
Journal title :
Journal of the Marine Biological Association of the United Kingdom
ISSN :
0025-3154
eISSN :
1469-7769
Publisher :
Cambridge Univ Press, New York, United States - New York
Bearhop, S., Adams, C.E., Waldron, S., Fuller, R.A. & Macleod, H., 2004. Determining trophic niche width: a novel approach using stable isotope analysis. Journal of Animal Ecology, 73, 1007-1012.
Chartock, M.A., 1983. Habitat and feeding observations on species of Ophiocoma (Ophiocomidae) at Enewetak. Micronesica, 19, 131-149.
Clark, A.M., 1976.Tropical epizoic echinoderms and their distribution. Micronesica, 12, 111-117.
Fourgon, D., 2006. Etude intégrée (écologique, éthologique et morphologique) d'une symbiose interophiuroidéenne dans l'écosyste' me corallien à Madagascar. PhD thesis, Free University of Brussels, Belgium.
Fry, B., 1988. Food web structure on Georges Bank from stable C, N, and S isotopic compositions. Limnology and Oceanography, 33, 1182-1190.
Hsieh, H.L., Kao, W.Y., Chen, C.P. & Liu, P.J., 2000. Detrital £ows through the feeding pathway of the oyster (Crassostrea gigas) in a tropical shallow lagoon: δ13C signals. Marine Biology, 136, 677-684.
Lepoint, G., Nyssen, F., Gobert, S., Dauby, P. & Bouquegneau, J.M., 2000. Relative impact of a Posidonia seagrass bed and its adjacent epilithic algal community in consumers diet. Marine Biology, 136, 513-518.
Magnus, D.B., 1967. Ecological and ethological studies and experiments on the echinoderms of the Red Sea. Studies in Tropical Oceanography, 5, 635-664.
Matthews, B. & Mazumder, A., 2004. A critical evaluation of intrapopulation variation of δ13C and isotopic evidence of individual specialization. Oecologia, 140, 361-371.
McConnaughey, T. & McRoy, C.P., 1979. Food-web structure and the fractionation of carbon isotopes in the Bering Sea. Marine Biology, 53, 257-262.
McCutchan, J.H., Lewis, W.M., Kendall, C. & McGrath, C.C., 2003. Variation in trophic shift for stable isotope ratios of carbon, nitrogen, and sulfur. Oikos, 102, 378-390.
Post, D.M., 2002. Using stable isotopes to estimate trophic position: models, methods and assumptions. Ecology, 83, 703-718.
Vanderklift, M.A. & Ponsard, S., 2003. Sources of variation in consumer-diet δ15N enrichment: a meta-analysis. Oecologia, 136, 169-182.
Vander Zanden, M.J & Rasmussen, J.B., 2001. Variation of δ15N and δ13C trophic fractionation: implication for aquatic food web studies. Limnology and Oceanography, 46, 2061-2066.
