Search

Your search keyword '"Pavanee Annasawmy"' showing total 4 results
Start Over Author "Pavanee Annasawmy" Publisher hal ccsd
4 results on '"Pavanee Annasawmy"'

1. Trace elements and δ15N values in micronekton of the south-western Indian Ocean

Author

Pavanee Annasawmy, Paco Bustamante, David Point, Carine Churlaud, Evgeny V. Romanov, Nathalie Bodin, Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Centre technique de recherche et de valorisation des milieux aquatiques (CITEB), and Sustainable Ocean Seychelles (SOS)

Subjects
Myctophids, Principal Component Analysis, Squids, Fishes, Seamounts, Body size, [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology, Aquatic Science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Oceanography, Pollution, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Crustaceans
Abstract

International audience; Trace elements and δ 15 N values were analysed in micronekton (crustaceans, fishes and squids) sampled in the southwestern Indian Ocean. Myctophids were associated with high concentrations of arsenic at La Pérouse and MAD-Ridge seamounts, and with lead and manganese at MAD-Ridge and in the Mozambique Channel. The difference in cadmium, copper and zinc concentrations between micronekton broad categories reflected differing metabolic and storage processes. When significant, negative relationships were found between micronekton body size and trace element concentrations, which can possibly be attributed to differing metabolic activity in young and old individuals, dietary shifts and/or dilution effect of growth. No relationships were found between trace element concentrations and δ 15 N values of micronekton (except cobalt which decreased with increasing δ 15 N values), since most trace elements are not biomagnified in food webs due to regulation and excretion processes within organisms. All trace element pairs were positively correlated in fishes suggesting regulation processes.

Published
2022
Full Text
View/download PDF

2. Micronekton distribution as influenced by mesoscale eddies, Madagascar shelf and shallow seamounts in the south-western Indian Ocean: an acoustic approach

Author

Pascal Cotel, Steven Herbette, Pavanee Annasawmy, Jean-François Ternon, Anne Lebourges-Dhaussy, Francis Marsac, Frédéric Ménard, Gildas Roudaut, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), University of Cape Town, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), The study was mainly supported by the Flotte Océanographique Française (French Oceanographic Fleet) and the Institut de Recherche pour le Développement (IRD) in relation to the logistics of the RV Antea. Additional funding was received from the Conseil Régional de la Reunion (Réunion Regional Council, Bop 123/2016) for the La Pérouse cruise, and from the Fonds Français pour l’Environnement Mondial (FFEM) as part of the FFEM-SWIO project on Areas Beyond National Jurisdiction (ABNJ) of the South West Indian Ocean for the MAD-Ridge cruise. The first author was the beneficiary of a doctoral bursary granted by IRD (France) and the ICEMASA French-South African International Laboratory., Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, Diel vertical migration, 010504 meteorology & atmospheric sciences, Mesopelagic zone, Seamount, Mesoscale meteorology, Oceanography, 01 natural sciences, South-western indian ocean, Water column, Ocean gyre, Mesoscale eddies, 14. Life underwater, Micronekton, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Multi-frequency, 010604 marine biology & hydrobiology, Acl, Madagascar shelf, 13. Climate action, Anticyclone, Cyclone, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Geology
Abstract

International audience; An investigation of the vertical and horizontal distributions of micronekton, as influenced by mesoscale eddies, the Madagascar shelf and shallow seamounts, was undertaken using acoustic data collected during two research cruises at an unnamed pinnacle (summit depth ~240 m) thereafter named “MAD-Ridge”, and at La Pérouse seamount (~60 m) in the south-western Indian Ocean. MAD-Ridge is located to the south of Madagascar, in an “eddy corridor”, known both for its high mesoscale activity and high primary productivity. In contrast, La Pérouse is located on the outskirts of the Indian South Subtropical Gyre (ISSG) province, characterised by low mesoscale activity and low primary productivity. During the MAD-Ridge cruise, a dipole was located in the vicinity of the seamount, with the anticyclone being almost stationary on the pinnacle. Total micronekton acoustic densities were greater at MAD-Ridge than at La Pérouse. Micronekton acoustic densities of the total water column were lower within the anticyclone than within the cyclone during MAD-Ridge. Micronekton followed the usual diel vertical migration (DVM) pattern, except within the cyclone during MAD-Ridge where greater acoustic densities were recorded in the daytime surface layer. The backscatter intensities were stronger at the 38 kHz than at the 70 and 120 kHz frequencies in the daytime surface layer at MAD-Ridge cyclonic stations. These backscatter intensities likely correspond to gas-filled swimbladders of epi- and mesopelagic fish actively swimming and feeding within the cyclone or gelatinous organisms with gas inclusions. Our findings evidenced that the distributions of micronekton and DVM patterns are complex and are influenced significantly by physical processes within mesoscale eddies. The mesoscale eddies’ effects were dominant over any potential seamount effects at the highly dynamic environment prevailing at MAD-Ridge during the cruise. No significant increase in total micronekton acoustic densities was observed over either seamount, but dense aggregations of biological scatterers were observed on their summits during both day and night.

Published
2020
Full Text
View/download PDF

3. Micronekton distributions and assemblages at two shallow seamounts of the south-western Indian Ocean: Insights from acoustics and mesopelagic trawl data

Author

Gildas Roudaut, Evgeny V. Romanov, Yves Cherel, Pavanee Annasawmy, Frédéric Ménard, Anne Lebourges-Dhaussy, Jean-François Ternon, Pascal Cotel, Francis Marsac, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), University of Cape Town, Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Centre technique d’appui à la pêche réunionnaise (CAP RUN)-NEXA [Ile de la Réunion], Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), Aix Marseille Université (AMU), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Marine Research Institute and Department of Biological Sciences, Institut National de la Recherche Agronomique (INRA)-Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD [France-Ouest])

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, Mesopelagic zone, Seamount, Mesoscale meteorology, Aquatic Science, 01 natural sciences, Ocean gyre, Sunrise, Deep scattering layer, 14. Life underwater, Micronekton, Diel vertical migration, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, 010604 marine biology & hydrobiology, ACL, Geology, South-western Indian Ocean, Acoustics, Seamount-associated fauna, Oceanography, Productivity (ecology), [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

International audience; Micronekton distributions and assemblages were investigated at two shallow seamounts of the south-western Indian Ocean using a combination of trawl data and multi-frequency acoustic visualisation techniques. La Pérouse (∼60 m) seamount is located on the outskirts of the oligotrophic Indian South Subtropical Gyre province with weak mesoscale activities and low primary productivity all year round. The “MAD-Ridge” seamount (thus termed in this study; ∼240 m) is located in the productive East African Coastal (EAFR) province with high mesoscale activities to the south of Madagascar. This resulted in higher micronekton species richness at MAD-Ridge compared to La Pérouse. Resulting productivity at MAD-Ridge seamount was likely due to the action of mesoscale eddies advecting larvae and productivity from the Madagascar shelf rather than local dynamic processes such as Taylor column formation. Mean micronekton abundance/biomass, as estimated from mesopelagic trawl catches, were lower over the summit compared to the vicinity of the seamounts, due to net selectivity and catchability and depth gradient on micronekton assemblages. Mean acoustic densities in the night shallow scattering layer (SSL: 10-200 m) over the summit were not significantly different compared to the vicinity (within 14 nautical miles) of MAD-Ridge. At La Pérouse and MAD-Ridge, the night and day SSL were dominated by common diel vertical migrant and non-migrant micronekton species respectively. While seamount-associated mesopelagic fishes such as Diaphus suborbitalis (La Pérouse and MAD-Ridge) and Benthosema fibulatum performed diel vertical migrations (DVM) along the seamounts’ flanks, seamount-resident benthopelagic fishes, including Cookeolus japonicus (MAD-Ridge), were aggregated over MAD-Ridge summit both during the day and night. Before sunrise, mid-water migrants initiated the first vertical migration event from the intermediate to the deep scattering layer (DSL, La Pérouse: 500-650m; MAD-Ridge: 400-700 m) or deeper. During sunrise, the other taxa contributing to the night SSL exhibited a successive series of vertical migration events from the surface to the DSL or deeper. Some scatterers were blocked in their upward and downward migrations due to the seamount topography, more commonly known as the sound scattering layer interception/topographic blockage hypothesis. Possible mechanisms leading to the observed patterns in micronekton vertical and horizontal distributions are discussed. This study contributes to a better understanding of how seamounts influence the diel vertical migration, horizontal distribution and community composition of micronekton and seamount-associated/resident species at two poorly studied shallow topographic features in the south-western Indian Ocean.

Published
2019
Full Text
View/download PDF

4. Micronekton diel migration, community composition and trophic position within two biogeochemical provinces of the South West Indian Ocean: Insight from acoustics and stable isotopes

Author

Gildas Roudaut, Hervé Demarcq, C.L. Moloney, Pavanee Annasawmy, Sébastien Jaquemet, Yves Cherel, J.-F. Ternon, Francis Marsac, Anne Lebourges-Dhaussy, Nolwenn Behagle, Frédéric Ménard, Marine Research Institute and Department of Biological Sciences, University of Cape Town, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Institut National de la Recherche Agronomique (INRA)-Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Ecologie marine tropicale dans les Océans Pacifique et Indien (ENTROPIE [Réunion]), Institut de Recherche pour le Développement (IRD)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA)-Université de La Rochelle (ULR), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Institut de Recherche pour le Développement (IRD), Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, Biogeochemical cycle, Diel vertical migration, 010504 meteorology & atmospheric sciences, Mesopelagic zone, Aquatic Science, Oceanography, Spatial distribution, 010603 evolutionary biology, 01 natural sciences, Trophic level, East African Coastal province, Ocean gyre, 14. Life underwater, Micronekton, 0105 earth and related environmental sciences, Ecological niche, geography, geography.geographical_feature_category, Swordfish, ACL, 13. Climate action, Indian South Subtropical Gyre, [SDE]Environmental Sciences, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

Spatial distribution, community composition and trophic roles of micronekton (crustaceans, fishes and squids) were investigated in the Indian South Subtropical Gyre (ISSG) province and the East African Coastal province (EAFR), by combining acoustic surveys, mid-water trawls and stable isotope analyses from scientific cruises conducted in 2009 and 2010. Mesopelagic micronekton performed diel vertical migrations in both provinces, from deep (400–740 m) to surface (0–200 m) layers at dusk and in the opposite direction at dawn, with some species migrating below 740 m. The EAFR province was more dynamic than the oligotrophic ISSG province, with enhanced eddy activity and enhanced yearly productivity. The active enrichment mechanisms in the EAFR, in terms of available primary production, led to high micronekton acoustic density (as a proxy of micronekton abundance) and large micronekton weight and abundance estimates from trawl data. Particulate organic matter in the EAFR exhibited greater enrichment in 13 C and 15 N compared to the ISSG and, consequently, tissues of selected micronekton organisms in the EAFR were more enriched in 15 N (higher δ 15 N values). In both provinces, micronekton encompassed a wide range of isotopic niches, with large overlaps between species. Micronekton and swordfish in the EAFR had an overlapping range of δ 15 N values, contrasting with the ISSG province where swordfish were two trophic levels higher than the sampled micronekton. Our results provide some evidence that the combined action of riverine input and the dynamics of eddies might influence productivity in the EAFR, and hence the abundance of micronekton and the enrichment of tissues in 15 N, compared to the oligotrophic ISSG province.

Published
2018
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results