Multi-decadal changes in two co-occurring ophiuroid populations

Blanchet-Aurigny, Aline; Dubois, Stanislas F.; Hily, Christian; Rochette, Sébastien; Goaster, E. Le; Guillou, Monique

doi:10.3354/meps09784

Cited by 8 publications

(12 citation statements)

References 57 publications

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“…Carré Renard hosts a population of a small echinoderm (Ophiocomina nigra) structuring the benthic habitat (Blanchet-Aurigny et al 2012). This population has been monitored many times since the 1990s, with the conclusion that after an increase of the population between early 1990s and 2011, the density and structure of the seabed are now stable and do not show significant seasonal fluctuations (BlanchetAurigny, pers.…”

Section: Carré Renard Reference Areamentioning

confidence: 99%

Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas

Roche¹,

Degrendele²,

Vrignaud

et al. 2018

Mar Geophys Res

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The increased use of backscatter measurements in time series for environmental monitoring necessitates the comparability of individual results. With the current lack of pre-calibrated multibeam echosounder systems for absolute backscatter measurement, a pragmatic solution is the use of natural reference areas for ensuring regular assessment of the backscatter measurement repeatability. This method mainly relies on the assumption of a sufficiently stable reference area regarding its backscatter signature. The aptitude of a natural area to provide a stable and uniform backscatter response must be carefully considered and demonstrated by a sufficiently long time-series of measurements. Furthermore, this approach requires a strict control of the acquisition and processing parameters. If all these conditions are met, stability check and relative calibration of a system are possible by comparison with the averaged backscatter values for the area. Based on a common multibeam echosounder and sampling campaign completed by available bathymetric and backscatter time series, the suitability as a backscatter reference area of three different candidates was evaluated. Two among them, Carré Renard and Kwinte, prove to be excellent choices, while the third one, Western Solent, lacks sufficient data over time, but remains a valuable candidate. The case studies and the available backscatter data on these areas prove the applicability of this method. The expansion of the number of commonly used reference areas and the growth of the number of multibeam echosounder controlled thereon could greatly contribute to the further development of quantitative applications based on multibeam echosounder backscatter measurements.

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Section: Carré Renard Reference Areamentioning

confidence: 99%

Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas

Roche¹,

Degrendele²,

Vrignaud

et al. 2018

Mar Geophys Res

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“…Although this species assemblage is reported to be stable over time and is usually dominated by O. fragilis (Hily 1991), recent investigations in Brittany revealed long-term density changes and spatial shifts in O. nigra and O. fragilis beds between 1987(Blanchet-Aurigny et al 2012a, Guillou et al 2013. It was hypothesized that a combination of changes in food supply and the biological traits of O. nigra were a key factor of its proliferation in this area (Blanchet-Aurigny et al 2012a).…”

Section: Introductionmentioning

confidence: 97%

“…nigra and O. fragilis beds between 1987(Blanchet-Aurigny et al 2012a, Guillou et al 2013. It was hypothesized that a combination of changes in food supply and the biological traits of O. nigra were a key factor of its proliferation in this area (Blanchet-Aurigny et al 2012a). As demonstrated with other echinoderms, it was suggested that flexibility in feeding habits (Thrush & Cummings 2011) as well as an increase in fecundity and fertilization (Sewell & Levitan 1992) contributed to the species' success.…”

Section: Introductionmentioning

confidence: 99%

Trophic niche of two co-occurring ophiuroid species in impacted coastal systems, derived from fatty acid and stable isotope analyses

Blanchet-Aurigny¹,

Dubois²,

Quéré³

et al. 2015

Mar. Ecol. Prog. Ser.

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The trophic niches of 2 common co-occurring ophiuroids, Ophiocomina nigra and Ophiothrix fragilis (Echinodermata, Ophiuroidea), in 2 contrasting coastal systems of Brittany (France) were investigated. We used a combination of fatty acid biomarkers derived from neutral lipids and stable isotopic compositions to explore the contributions of oceanic versus continental inputs to the ophiuroids' diet. We investigated 2 different systems with an inshore versus offshore comparison. We sampled potential food sources and surveyed organisms every 2 mo for 1 yr. Spatio-temporal variations in stable isotopes and fatty acid profiles of the ophiuroids were generally low compared to interspecific differences. Fatty acid markers showed that both ophiuroids relied on diatom inputs. However, a more δ 15 N-enriched isotopic composition as well as a more balanced plant-versus animal-derived fatty acid composition in O. nigra suggest that a broader range of food sources are being used by this species irrespective of location or sampling time. The positive correlation between the 18:1n-9/18:1n-7 fatty acid ratio and δ 15 N values indicates a higher trophic position for O. nigra (suggesting an omnivorous feeding mode), whereas O. fragilis appears to be more herbivorous. Moreover, the low polyunsaturated/saturated fatty acid ratio associated with elevated bacterial fatty acid markers indicates that O. nigra preferentially consumes detritus, while O. fragilis relies more on fresh phytoplankton-derived material. Both stable isotope and fatty acid analyses suggest that terrestrial inputs do not contribute significantly to the diet of these ophiuroids. However, phytodetritus derived from decomposing green macroalgae contributed to the diet of O. nigra in the Bay of Douarnenez.KEY WORDS: Echinoderm · Feeding ecology · Ophiocomina nigra · Ophiothrix fragilis · Trophic markers · Green algae Resale or republication not permitted without written consent of the publisher

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“…the bay of Douarnenez and the bay of Brest, over the last twenty years 11,12 . Blanchet-Aurigny et al 11,13 argued that changes in food supply to adults in response to eutrophication, with the proliferation of green macroalgae, could be the primary cause of the population outbreak of this species which displays a wide trophic plasticity. Therefore, following a fivefold increase in density and a threefold increase in biomass in the bay of Brest, O. nigra became the predominant primary consumer within the benthic habitats of this bay with strong impacts on the community structure and the bentho-pelagic coupling.…”

mentioning

confidence: 99%

“…One major impact was the significant decline of the populations of the co-occurring brittle-star Ophiothrix fragilis (Abildgaard in O.F. Müller, 1789) which was previously dominant in the two bays 11,12 (Blanchet-Aurigny, pers. obs.…”

mentioning

confidence: 99%

Vertical distribution of brittle star larvae in two contrasting coastal embayments: implications for larval transport

Guillam

Bessin

Blanchet-Aurigny

et al. 2020

Sci Rep

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the ability of marine invertebrate larvae to control their vertical position shapes their dispersal pattern. in species characterized by large variations in population density, like many echinoderm species, larval dispersal may contribute to outbreak and die-off phenomena. A proliferation of the ophiuroid Ophiocomina nigra was observed for several years in western Brittany (france), inducing drastic changes on the benthic communities. We here studied the larval vertical distribution in this species and two co-occurring ophiuroid species, Ophiothrix fragilis and Amphiura filiformis, in two contrasting hydrodynamic environments: stratified in the bay of Douarnenez and well-mixed in the bay of Brest. Larvae were collected at 3 depths during 25 h within each bay. In the bay of Brest, all larvae were evenly distributed in the water column due to the intense vertical mixing. Conversely, in the bay of Douarnenez, a diel vertical migration was observed for O. nigra, with a night ascent of young larvae, and ontogenetic differences. These different patterns in the two bays mediate the effects of tidal currents on larval fluxes. O. fragilis larvae were mainly distributed above the thermocline which may favour larval retention within the bay, while A. filiformis larvae, mostly concentrated near the bottom, were preferentially exported. This study highlighted the complex interactions between coastal hydrodynamics and specific larval traits, e.g. larval morphology, in the control of larval vertical distribution and larval dispersal.

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Multi-decadal changes in two co-occurring ophiuroid populations

Cited by 8 publications

References 57 publications

Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas

Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas

Trophic niche of two co-occurring ophiuroid species in impacted coastal systems, derived from fatty acid and stable isotope analyses

Vertical distribution of brittle star larvae in two contrasting coastal embayments: implications for larval transport

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