The populations of two epibenthic ophiuroids Ophiothrix fragilis and Ophiocomina nigra at the tip of Brittany (France) : evolution and trophic ecology
type: Dataset
description: The temporal and spatial changes in the densities and biomass of two co-occurring ophiuroid populations Ophiocomina nigra and Ophiothrix fragilis (Ophiuroidea, Echinodermata) were studied in two contrasted coastal systems at the tip of Brittany (France); the Bay of Brest and the Bay of Douarnenez. Ophiocomina nigra increased about 5 times in density in the Bay of Brest. The current distribution pattern in this site revealed a spatial exclusion of O. fragilis from the central part toward the southern part of the study area and now overlapped dead slimper-limpet Crepidula fornicata beds. 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. Stable isotopes (δ13C and δ15N) and fatty acids were used as complementary tools to characterize the trophic ecology of these 2 ophiuroids. Preliminary, the tissue-diet discrimination factors (Δδ13C and Δδ15N) were studied and revealed differences between species but appeared to be mainly driven by the diet and to a lesser extent the physiological state of the organisms. We designed a field survey and used the dual stable isotope and fatty acid biomarkers approach to explore the contribution of oceanic vs continental inputs to the diet of ophiurids, according to seasons. In our study, spatiotemporal variations in stable isotopes and fatty acid profiles of ophiurids were generally low compared to interspecific differences. Both ophiurids rely mainly on phytoplankton (diatoms) inputs with higher contribution for O. fragilis. The more δ15N-enriched values as well as higher contribution of bacteria, detritus and animal material inputs to the diet of O.nigra supported a broad range of food sources to the diet of O. nigra. The terrestrial and/or green algae did not contribute greatly to the diet of ophiurids despite a significant increase of these food sources at the end of the study period in both inside sites.
identifier: NNT: 2012BRES0041
issued: 2026-05-09T17:01:25.301600
language: fr
modified: 2026-05-09T17:01:25.301604
contact point: Organization
  fn: CCSD
keyword: 15n
keyword: acides-gras
keyword: bretagne-finistere
keyword: brittany-finistere
keyword: echinodermes
keyword: echinoderms
keyword: ecologie-trophique
keyword: facteurs-de-discrimination-13c
keyword: fatty-acids
keyword: infoeu-reposemanticsdoctoralthesis
keyword: isotopes-stables
keyword: matiere-organique
keyword: organic-matter
keyword: proliferation
keyword: sdvbalife-sciences-q-bioanimal-biology
keyword: stable-isotopes
keyword: theses
keyword: tissue-diet-discrimination-factors-13c
keyword: trophic-ecology
landing page: https://theses.hal.science/tel-00863260

The populations of two epibenthic ophiuroids Ophiothrix fragilis and Ophiocomina nigra at the tip of Brittany (France) : evolution and trophic ecology
type: Distribution
format: HTML
issued: 2026-05-09T17:01:25.303794
modified: 2026-05-09T17:01:25.280223
access URL: https://theses.hal.science/tel-00863260

test_moissonnage_selune
type: Agent