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Auteur Rossi, F.; Baeta, A.; Marques, J.C.
Titre Stable isotopes reveal habitat-related diet shifts in facultative deposit-feeders Type Article scientifique
Année 2015 Publication Revue Abrégée J. Sea Res.
Volume 95 Numéro Pages 172-179
Mots-Clés Benthos; burying depth; carbon; Estuaries; estuarine habitats; food-web; Macrofauna; marine; polychaete nereis-diversicolor; scrobicularia-plana; Seagrass; seagrass meadows; Sediment; water-flow; zostera-noltii
Résumé Seagrass patches interspersed in a sediment matrix may vary environmental conditions and affect feeding habits of consumers and food-web structure. This paper investigates diet shifts between bare sediments and a Zostera noltei (Hornemann, 1832) meadow for three facultative deposit-feeding macrofaunal consumers, notably the bivalve Scrobicularia piano (da Costa, 1778), the polychaete Hediste diversicolor (O.T. Muller, 1776), and the gastropod Hydrobia ulvae (Pennant, 1778). In July 2008, one eelgrass meadow and two bare sediment locations were chosen in the Mondego estuary (40 degrees 08" N, 8 degrees 50'W, Portugal) and sampled for stable isotope signatures (delta C-13 and delta N-15) of macrofauna consumers and some of their potential basal food sources, such as sedimentary organic matter (SOM), microphytobenthos (MPB), seagrass shoots, leaves and seaweeds laying on the surface sediment. The delta N-15 of H. diversicolor was 3% higher in the eelgrass meadow than in bare sediment, indicating a change of trophic position, whereas the Bayesian stable-isotope mixing model showed that S. piano assimilated more macroalgal detritus than microphytobenthos in the eelgrass bed. Such habitat-related diet shifts have the potential to change structure and spatial dynamics of benthic food webs. (C) 2014 Elsevier B.V. All rights reserved.
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Volume de collection Numéro de collection Edition
ISSN 1385-1101 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1549
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Auteur Vianello, P.; Ternon, J.-F.; Demarcq, H.; Herbette, S.; Roberts, M.J.
Titre Ocean currents and gradients of surface layer properties in the vicinity of the Madagascar Ridge (including seamounts) in the South West Indian Ocean Type Article scientifique
Année 2020 Publication Revue Abrégée Deep-Sea Res. Part II-Top. Stud. Oceanogr.
Volume 176 Numéro Pages 104816
Mots-Clés agulhas current; biology; bloom; Chlorophyll-a; communities; dipoles; Eddy kinetic energy; fauna; Geostrophic currents; Madagascar Ridge; mesoscale eddies; Mixed layer depth; retroflection; Sea surface temperature; Seamounts; South West Indian Ocean; terms; variability; Walters shoal
Résumé This work is part of the MADRidge Project special issue which aims to describe pelagic ecosystems in the vicinity of three prominent shallow seamounts in the South West Indian Ocean: one here named MAD-Ridge (240 m below the surface) plus Walters Shoal (18 m) on the Madagascar Ridge, and La Perouse (60 m) on the abyssal plain east of Madagascar. The three span latitudes 20 degrees S and 33 degrees S, some 1500 km. The study provides the background oceanography for the once-off, multidisciplinary snapshot cruise studies around the seamounts. As life on seamounts is determined by factors such as summit depth, proximity to the light layers of the ocean, and the ambient circulation, a first description of regional spatial-field climatologies (16-22 years) and monthly along-ridge gradients of surface wind (driving force), water column properties of sea surface temperature, mixed layer depth, chlorophyll-a and eddy kinetic energy, plus ocean currents is provided. Being relevant to many applications in the study domain, these properties in particular reveal contrasting environments along the Madagascar Ridge and between the three seamounts that should drive biological differences. Relative to the other two seamounts, MAD-Ridge is in the more extreme situation, being at the end of the East Madagascar Current, where it experiences sturdy, albeit variable, currents and the frequent passing of mesoscale eddies.
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Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0967-0645 ISBN Médium
Région Expédition Conférence
Notes WOS:000556810400013 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2859
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Auteur Zhou, C.; He, P.; Xu, L.; Bach, P.; Wang, X.; Wan, R.; Tang, H.; Zhang, Y.
Titre The effects of mesoscale oceanographic structures and ambient conditions on the catch of albacore tuna in the South Pacific longline fishery Type Article scientifique
Année 2020 Publication Revue Abrégée Fisheries Oceanography
Volume Numéro Pages
Mots-Clés albacore tuna; environmental conditions; hook depth; longline; ocean eddy; ocean fronts; South Pacific Ocean
Résumé Albacore tuna (Thunnus alalunga) exhibit patchy concentrations associated with biological process at a wide range of spatial scales, resulting in variations in their catchability by fishing gears. Here, we investigated the association of catch variation for pelagic longlines in the South Pacific Ocean with oceanographic mesoscale structures (in horizontal dimension) and ambient conditions (in vertical dimension). The distribution of albacore tuna as indicated by catch per unit effort (CPUE) of longlines was significantly related to the presence of mesoscale structures, with higher CPUE found at locations closer to thermal fronts and with greater gradient magnitudes, as well as areas marked by peripheral contour line of the anticyclone indicated by Sea Surface Height Anomalies 0.05 m. Surface mesoscale current velocity had the negative effect on the catch, probably as a result of decreased catchability by shoaling the hook depth. Vertical distribution of albacore in the survey region of South Pacific Ocean was hardly restricted by ambient temperature and oxygen concentration, though effect of ambient temperature was relevant and showed a negatively linear correlation with CPUE at the range of 20–24°C. On the contrary, albacore distribution was evidently dominated by the water depth and showed strong preference on water depth of 200 m, which was likely a representative feeding layer. The presence of prey resources and their accessibility by albacore revealed by mesoscale structures in the biological and physical processes, and catchability determined by the location of the baited hooks comprehensively contribute to the variability of catch.
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ISSN 1365-2419 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2732
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