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Auteur (down) Ram, P.A.S.; Mari, X.; Brune, J.; Torreton, J.P.; Chu, V.T.; Raimbault, P.; Niggemann, J.; Sime-Ngando, T.
Titre Bacterial-viral interactions in the sea surface microlayer of a black carbon-dominated tropical coastal ecosystem (Halong Bay, Vietnam) Type Article scientifique
Année 2018 Publication Revue Abrégée Elementa-Sci. Anthrop.
Volume 6 Numéro Pages 13
Mots-Clés dissolved organic-matter; marine; communities; seawater; lysogeny; black carbon; variability; viruses; waters; aquatic ecosystems; hexane soot; ocean surface; sea surface microlayer; tropical coastal ocean; viral lysis; virus-bacteria interaction
Résumé Increasing human activity has raised concerns about the impact of deposition of anthropogenic combustion aerosols (i.e., black carbon; BC) on marine processes. The sea surface microlayer (SML) is a key gate for the introduction of atmospheric BC into the ocean; however, relatively little is known of the effects of BC on bacteria-virus interactions, which can strongly influence microbially mediated processes. To study the impact of BC on bacteria-virus interactions, field investigations involving collection from the SML and underlying water were carried out in Halong Bay (Vietnam). Most inorganic nutrient concentrations, as well as dissolved organic carbon, were modestly but significantly higher (p = 0.02-0.05) in the SML than in underlying water. The concentrations of particulate organic carbon (though not chlorophyll a) and of total particulate carbon, which was composed largely of particulate BC (mean = 1.7 +/- 6.4 mmol L-1), were highly enriched in the SML, and showed high variability among stations. On average, microbial abundances (both bacteria and viruses) and bacterial production were 2- and 5fold higher, respectively, in the SML than in underlying water. Significantly lower bacterial production (p < 0.01) was observed in the particulate fraction (> 3 mu m) compared to the bulk sample, but our data overall suggest that bacterial production in the SML was stimulated by particulate BC. Higher bacterial production in the SML than in underlying water supported high viral lytic infection rates (from 5.3 to 30.1%) which predominated over percent lysogeny (from undetected to 1.4%). The sorption of dissolved organic carbon by black carbon, accompanied by the high lytic infection rate in the black carbon-enriched SML, may modify microbially mediated processes and shift the net ecosystem metabolism (ratio of production and respiration) to net heterotrophy and CO2 production in this critical layer between ocean and atmosphere.
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Volume de collection Numéro de collection Edition
ISSN 2325-1026 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2276
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Auteur (down) Mostajir, B.; Le Floc'h, E.; Mas, S.; Pete, R.; Parin, D.; Nouguier, J.; Fouilland, E.; Vidussi, F.
Titre A new transportable floating mesocosm platform with autonomous sensors for real time data acquisition and transmission for studying the pelagic food web functioning Type Article scientifique
Année 2013 Publication Revue Abrégée Limnol Oceanogr-Meth
Volume 11 Numéro Pages 394-409
Mots-Clés Oxygen; diatom bloom; fluorescence; phytoplankton; planktonic community; respiration; seawater; technical note; ultraviolet-b radiation; winkler method
Résumé We describe a new transportable floating mesocosm platform with autonomous sensors. The platform has 9 separate units that can be transported by medium-sized research vessels and positioned in coastal waters. The in situ mesocosms are equipped with a set of sensors for measuring water temperature, conductivity, chlorophyll a fluorescence (Chl a), and dissolved oxygen concentration. It can take measurements every 2 min, store these measurements, and transmit them in real time. Each mesocosm has a pump with regulated flow to mix the water column. One of the floating units is used as an in situ observatory to monitor the water temperature and Chl a in the water around the mesocosms as well as weather data and the incident light. The main data logger on the platform sends all the data collected to a remote PC computer. This floating mesocosm platform was successfully deployed in 2010 and 2011 in Mediterranean coastal waters (Thau lagoon and Cretan Sea, respectively). Simultaneous, automatic, high temporal resolution monitoring of physical, chemical, and biological parameters in the mesocosms proved to be a powerful, noninvasive, and effective approach for i) monitoring the variations in physical and chemical parameters in real time and ii) assessing the short-term variations in Chl a and the pelagic food web metabolism (e.g., the community respiration, gross primary production, and net community production) in the mesocosms without any manipulation of water samples.
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Volume de collection Numéro de collection Edition
ISSN 1541-5856 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 394
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Auteur (down) Moreau, S.; Mostajir, B.; Bélanger, S.; Schloss, I.R.; Vancoppenolle, M.; Demers, S.; Ferreyra, G.A.
Titre Climate change enhances primary production in the western Antarctic Peninsula Type Article scientifique
Année 2015 Publication Revue Abrégée Glob Change Biol
Volume 21 Numéro 6 Pages 2191-2205
Mots-Clés ozone hole; photoinhibition; primary production; regional warming; sea ice; seawater temperature; ultraviolet radiation
Résumé Intense regional warming was observed in the western Antarctic Peninsula (WAP) over the last 50 years. Here, we investigate the impact of climate change on primary production (PP) in this highly productive region. This study is based on temporal data series of ozone thickness (1972–2010), sea ice concentration (1978–2010), sea-surface temperature (1990–2010), incident irradiance (1988–2010) and satellite-derived chlorophyll a concentration (Chl-a, 1997–2010) for the coastal WAP. In addition, we apply a photosynthesis/photoinhibition spectral model to satellite-derived data (1997–2010) to compute PP and examine the separate impacts of environmental forcings. Since 1978, sea ice retreat has been occurring earlier in the season (in March in 1978 and in late October during the 2000s) while the ozone hole is present in early spring (i.e. August to November) since the early 1990s, increasing the intensity of ultraviolet-B radiation (UVBR, 280–320 nm). The WAP waters have also warmed over 1990–2010. The modelled PP rates are in the lower range of previously reported PP rates in the WAP. The annual open water PP in the study area increased from 1997 to 2010 (from 0.73 to 1.03 Tg C yr−1) concomitantly with the increase in the production season length. The coincidence between the earlier sea ice retreat and the presence of the ozone hole increased the exposure to incoming radiation (UVBR, UVAR and PAR) and, thus, increased photoinhibition during austral spring (September to November) in the study area (from 0.014 to 0.025 Tg C yr−1). This increase in photoinhibition was minor compared to the overall increase in PP, however. Climate change hence had an overall positive impact on PP in the WAP waters.
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ISSN 1365-2486 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1339
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Auteur (down) Maugars, G.; Manirafasha, M.-C.; Grousset, E.; Boulo, V.; Lignot, J.-H.
Titre The effects of acute transfer to freshwater on ion transporters of the pharyngeal cavity in European seabass (Dicentrarchus labrax) Type Article scientifique
Année 2018 Publication Revue Abrégée Fish Physiol. Biochem.
Volume 44 Numéro 5 Pages 1393-1408
Mots-Clés atlantic salmon; atpase alpha-1 isoforms; branchial chloride cells; carbonic-anhydrase; Dicentrarchus labrax; gill na+/k+-atpase; Gills and extrabranchial organs; Ion transporters; k+-atpase; mitochondrion-rich cells; Osmoregulation; salinity transfer; salmon salmo-salar; seawater acclimation; Seawater to freshwater transfer; Teleost fish
Résumé Gene expression of key ion transporters (the Na+/K+-ATPase NKA, the Na+, K+-2Cl(-) cotransporter NKCC1, and CFTR) in the gills, opercular inner epithelium, and pseudobranch of European seabass juveniles (Dicentrarchus labrax) were studied after acute transfer up to 4days from seawater (SW) to freshwater (FW). The functional remodeling of these organs was also studied. Handling stress (SW to SW transfer) rapidly induced a transcript level decrease for the three ion transporters in the gills and operculum. NKA and CFTR relative expression level were stable, but in the pseudobranch, NKCC1 transcript levels increased (up to 2.4-fold). Transfer to FW induced even more organ-specific responses. In the gills, a 1.8-fold increase for NKA transcript levels occurs within 4days post transfer with also a general decrease for CFTR and NKCC1. In the operculum, transcript levels are only slightly modified. In the pseudobranch, there is a transient NKCC1 increase followed by 0.6-fold decrease and 0.8-fold CFTR decrease. FW transfer also induced a density decrease for the opercular ionocytes and goblet cells. Therefore, gills and operculum display similar trends in SW-fish but have different responses in FW-transferred fish. Also, the pseudobranch presents contrasting response both in SW and in FW, most probably due to the high density of a cell type that is morphologically and functionally different compared to the typical gill-type ionocyte. This pseudobranch-type ionocyte could be involved in blood acid-base regulation masking a minor osmotic regulatory capacity of this organ compared to the gills.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0920-1742 ISBN Médium
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Notes Approuvé pas de
Numéro d'Appel MARBEC @ alain.herve @ collection 2417
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Auteur (down) Masroor, W.; Farcy, E.; Blondeau-Bidet, E.; Venn, A.; Tambutte, E.; Lorin-Nebel, C.
Titre Effect of salinity and temperature on the expression of genes involved in branchial ion transport processes in European sea bass Type Article scientifique
Année 2019 Publication Revue Abrégée J. Therm. Biol.
Volume 85 Numéro Pages Unsp-102422
Mots-Clés cftr anion channel; chloride channel; cod gadus-morhua; Dicentrarchus labrax; dicentrarchus-labrax; fresh-water; functional classification; Gill; h+-atpase; Ion transporter; mRNA expression; na+/k+-atpase; na+/k+/2cl(-) cotransporter; Salinity; seawater-acclimated medaka; Thermal acclimation
Résumé The responses of European sea bass to temperature increase and salinity decrease were investigated measuring mRNA expression levels of main genes involved in ion transport. Juvenile fish were pre-acclimated to seawater (SW) at 18 degrees C (temperate) or 24 degrees C (warm) for two weeks and then transferred for two weeks to either fresh water (FW) or SW at the respective temperature. Unlike temperate conditions, there is no change in Na+/K+-ATPase ala (nka ala) and Na+/H+ exchanger 3 (nhe3) mRNA expression following FW transfer in warm conditions. This is linked to the high expression of these genes in warm SW compared to temperate SW. Na+/Cl--cotransporter (ncc2a) expression however is increased following FW transfer in temperate and warm conditions. Main transporters involved in ion excretion (Na+/K+/2Cl-1( )cotransporter, nkcc1 and cystic fibrosis transmembrane conductance regulator, cftr) as well as nitrogen excretion (Rh-glycoproteins, rhcg1 and rhbg) and acid-base regulation (V-H+-ATPase, vha-a and b) are highly expressed in SW warm conditions vs FW warm. Overall, our results suggest a higher activation of ion transport processes in warm conditions and more strikingly in SW. This is linked to a strong interplay between diverse ion transporters in order to coordinate physiological responses at the gill level.
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Langue English Langue du Résumé Titre Original
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ISSN 0306-4565 ISBN Médium
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Notes WOS:000497246100023 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2669
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