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Marine Ecology Progress Series

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MEPS 460:79-90 (2012)  -  DOI:

Multi-decadal changes in two co-occurring ophiuroid populations

A. Blanchet-Aurigny1,*, S. F. Dubois1, C. Hily2, S. Rochette3, E. Le Goaster1,2, M. Guillou2

1IFREMER, Laboratoire d’Ecologie Benthique, Département Océanographie et Dynamique des Ecosystèmes, Centre de Bretagne, BP70, 29280 Plouzané, France
2Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, LEMAR UMR CNRS IRD 6539, Place Nicolas Copernic, 29280 Plouzané, France
3IFREMER, Laboratoire Applications Géomatiques, Département Océanographie et Dynamique des Ecosystèmes, Centre de Bretagne, BP70, 29280 Plouzané, France

ABSTRACT: Mixed beds of Ophiocomina nigra and Ophiothrix fragilis (Echinodermata, Ophiuroidea) are usually predominated by O. fragilis and are reported to be stable over time. The Bay of Brest (Brittany, France) is a highly productive ecosystem where both species co-occur in the main central part. Using a geostatistical approach, we tested for changes in O. nigra and O. fragilis density and total biomass patterns between 1987 and 2011. Our results highlighted an increase in O. nigra population size and the induction of a spatial shift of the co-occurring O. fragilis. O. nigra increased ~5 times in density and covered almost all the study area, while its density-dependent biomass increased ~3 times (22 t km−2, ash-free dry mass) between 1987 and 2011. Overall, the O. fragilis population decreased in density by ~30%, but its total biomass did not change over time. The current distribution pattern revealed a clear spatial exclusion of O. fragilis from the central part of the study area toward the southern part, overlapping beds of dead slipper limpet Crepidula fornicata, which were formerly considered to be the dominant suspension-feeder species in the bay. The success of O. nigra colonization is linked to its biological and functional traits, as well as deep changes in food supply over the studied period. Ecological consequences of such a large change in the benthic compartment of the bay are explored in the light of associated changes in environmental patterns.

KEY WORDS: Echinoderm · Ophiocomina nigra · Ophiothrix fragilis · Food supply · Kriging method · Suspension-feeder

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Cite this article as: Blanchet-Aurigny A, Dubois SF, Hily C, Rochette S, Le Goaster E, Guillou M (2012) Multi-decadal changes in two co-occurring ophiuroid populations. Mar Ecol Prog Ser 460:79-90.

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