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| Van Wambeke, France; Pulido, Elvira; Catala, Philippe; Dinasquet, Julie; Djaoudi, Kahina; Engel, Anja; Garel, Marc; Guasco, Sophie; Barbara, Marie; Nunige, Sandra; Taillandier, Vincent; Zancker, Birthe; Tamburini, Christian. |
| Ectoenzymatic activity, prokaryotic heterotrophic abundances and production were determined in the Mediterranean Sea. Sampling was carried out in the sub-surface, the deep chlorophyll maximum layer (DCM), the core of the Levantine intermediate waters and in the deeper part of the mesopelagic layers. Michaelis–Menten kinetics were assessed using a large range of concentrations of fluorogenic substrates (0.025 to 50 µM). As a consequence, Km (Michaelis–Menten half-saturation constant) and Vm (maximum hydrolysis velocity) parameters were determined for both low- and high-affinity enzymes for alkaline phosphatase, aminopeptidase (LAP) and β-glucosidase (βGLU). Based on the constant derived from the high-LAP-affinity enzyme (0.025–1 µM substrate concentration... |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00642/75452/76268.pdf |
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| Freney, Evelyn; Sellegri, Karine; Nicosia, Alessia; Trueblood, Jonathan T; Rinaldi, Matteo; Williams, Leah R; Prévôt, André Sh; Thyssen, Melilotus; Gregori, Gerald; Haëntjens, Nils; Dinasquet, Julie; Obernosterer, Ingrid; Van Wambeke, France; Engel, Anja; Zancker, Birthe; Desboeufs, Karine; Asmi, Eija; Timmonen, Hilka; Guieu, Cécile. |
| The organic mass fraction from sea spray aerosol (SSA) is currently a subject of intense research. The majority of this research is dedicated to measurements in ambient air, although recently a small number of studies have additionally focused on nascent sea spray aerosol. This work presents measurements collected during a five-week cruise in May and June 2017 in the central and western Mediterranean Sea, an oligotrophic marine region with low phytoplankton biomass. Surface seawater was continuously pumped into a bubble bursting apparatus to generate nascent sea spray aerosol. Size distributions were measured with a differential mobility particle sizer (DMPS). Chemical characterization of the submicron aerosol was performed with a time of flight aerosol... |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00688/80017/82995.pdf |
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| Gazeau, Frédéric; Ridame, Céline; Van Wambeke, France; Alliouane, Samir; Stolpe, Christian; Irisson, Jean-olivier; Marro, Sophie; Grisoni, Jean-michel; De Liège, Guillaume; Nunige, Sandra; Djaoudi, Kahina; Pulido-villena, Elvira; Dinasquet, Julie; Obernosterer, Ingrid; Catala, Philippe; Guieu, Cécile. |
| In Low Nutrient Low Chlorophyll areas, such as the Mediterranean Sea, atmospheric fluxes represent a considerable external source of nutrients likely supporting primary production especially during stratification periods. These areas are expected to expand in the future due to lower nutrient supply from sub-surface waters caused by enhanced stratification, likely further increasing the role of atmospheric deposition as a source of new nutrients to surface waters. Yet, whether plankton communities will react differently to dust deposition in a warmer and acidified environment remains an open question. The impact of dust deposition both in present and future climate conditions was assessed through three perturbation experiments in the open Mediterranean Sea.... |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00688/80015/82994.pdf |
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| Maranon, Emilio; Van Vambeke, France; Uitz, Julia; Boss, Emmanuel S; Dimier, Céline; Dinasquet, Julie; Engel, Anja; Haentjens, Nils; Perez-lorenzo, Maria; Taillandier, Vincent; Zancker, Birthe. |
| The deep chlorophyll maximum (DCM) is a ubiquitous feature of phytoplankton vertical distribution in stratified waters that is relevant to our understanding of the mechanisms that underpin the variability in photoautotroph ecophysiology across environmental gradients and has implications for remote sensing of aquatic productivity. During the PEACETIME (Process studies at the air-sea interface after dust deposition in the Mediterranean Sea) cruise, carried out from 10 May to 11 June 2017, we obtained 23 concurrent vertical profiles of phytoplankton chlorophyll a, carbon biomass and primary production, as well as heterotrophic prokaryotic production, in the western and central Mediterranean basins. Our main aims were to quantify the relative role of... |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00642/75454/76271.pdf |
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| Van Wambeke, France; Taillandier, Vincent; Deboeufs, Karine; Pullido-villena, Elvira; Dinasquet, Julie; Engel, Anja; Maranon, Emilio; Ridame, Céline; Guieu, Cécile. |
| The surface mixed layer (ML) in the Mediterranean Sea is a well stratified domain characterized by low macro-nutrient and low chlorophyll content, during almost 6 months of the year. Nutrient dynamics in the ML depend on allochthonous inputs, through atmospheric deposition and on biological recycling. Here we characterize the biogeochemical cycling of N in the ML by combining simultaneous in situ measurements of atmospheric deposition, nutrients, hydrological conditions, primary production, heterotrophic prokaryotic production, N2 fixation and leucine aminopeptidase activity. The measurements were conducted along a 4300 km transect across the central and western open Mediterranean Sea in spring 2017. Dry deposition was measured on a continuous basis while... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00659/77153/78527.pdf |
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| Gazeau, Frédéric; Van Wambeke, France; Maranon, Emilio; Perez-lorenzo, Maria; Alliouane, Samir; Stolpe, Christian; Blasco, Thierry; Leblond, Nathalie; Zancker, Birthe; Engel, Anja; Marie, Barbara; Dinasquet, Julie; Guieu, Cécile. |
| Although atmospheric dust fluxes from arid as well as human-impacted areas represent a significant source of nutrients to surface waters of the Mediterranean Sea, studies focusing on the evolution of the metabolic balance of the plankton community following a dust deposition event are scarce and none were conducted in the context of projected future levels of temperature and pH. Moreover, most of the experiments took place in coastal areas. In the framework of the PEACETIME project, three dust-addition perturbation experiments were conducted in 300-L tanks filled with surface seawater collected in the Tyrrhenian Sea (TYR), Ionian Sea (ION) and in the Algerian basin (FAST) onboard the R/V “Pourquoi Pas?” in late spring 2017. For each experiment, six tanks... |
| Tipo: Text |
Palavras-chave: Mediterranean Sea; Atmospheric deposition; Plankton community metabolism; Carbon export; Ocean acidification; Ocean warming. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00688/79967/82900.pdf |
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| Trueblood, Jonathan, V; Nicosia, Alessia; Engel, Anja; Zancker, Birthe; Rinaldi, Matteo; Freney, Evelyn; Thyssen, Melilotus; Obernosterer, Ingrid; Dinasquet, Julie; Belosi, Franco; Tovar-sanchez, Antonio; Rodriguez-romero, Araceli; Santachiara, Gianni; Guieu, Cecile; Sellegri, Karine. |
| Ice-nucleating particles (INPs) have a large impact on the climate-relevant properties of clouds over the oceans. Studies have shown that sea spray aerosols (SSAs), produced upon bursting of bubbles at the ocean surface, can be an important source of marine INPs, particularly during periods of enhanced biological productivity. Recent mesocosm experiments using natural seawater spiked with nutrients have revealed that marine INPs are derived from two separate classes of organic matter in SSAs. Despite this finding, existing parameterizations for marine INP abundance are based solely on single variables such as SSA organic carbon (OC) or SSA surface area, which may mask specific trends in the separate classes of INP. The goal of this paper is to improve the... |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00688/79985/82974.pdf |
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