Multi-decadal changes in two co-occurring ophiuroid populations

Mixed beds ofOphiocomina nigraandOphiothrix fragilis(Echinodermata, Ophiuroidea) are usually predominated byO. fragilisand 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 geostatis...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 2012-07, Vol.460, p.79-90
Main Authors: Blanchet-Aurigny, A., Dubois, S. F., Hily, C., Rochette, S., Le Goaster, E., Guillou, M.
Format: Article
Language:English
Subjects:
Average linear density
Biomass
Continental interfaces, environment
Crepidula fornicata
Density
Echinodermata
Echinoderms
Environmental Sciences
Marine
Ophiocomina nigra
Ophiothrix fragilis
Ophiuroidea
Population density
Population dynamics
Population ecology
Sciences of the Universe
Sediments
Slippers
Species
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Summary:Mixed beds ofOphiocomina nigraandOphiothrix fragilis(Echinodermata, Ophiuroidea) are usually predominated byO. fragilisand 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 inO. nigraandO. fragilisdensity and total biomass patterns between 1987 and 2011. Our results highlighted an increase inO. nigrapopulation size and the induction of a spatial shift of the co-occurringO. fragilis.O. nigraincreased ~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, theO. fragilispopulation decreased in density by ~30%, but its total biomass did not change over time. The current distribution pattern revealed a clear spatial exclusion ofO. fragilisfrom the central part of the study area toward the southern part, overlapping beds of dead slipper limpetCrepidula fornicata, which were formerly considered to be the dominant suspension-feeder species in the bay. The success ofO. nigracolonization 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.
ISSN:0171-8630
1616-1599
DOI:10.3354/meps09784