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| Mostajir, Behzad; Roques, Cecile; Bouvier, Corinne; Bouvier, Thierry; Fouilland, Eric; Got, Patrice; Le Floc'H, Emilie; Nouguier, Jean; Mas, Sebastien; Sempere, Richard; Sime-ngando, Telesphore; Troussellier, Marc; Vidussi, Francesca. |
| The impact of fish and oysters on components of the pelagic microbial food web (MFW) was studied in a 10 d mesocosm experiment using Mediterranean coastal waters. Two mesocosms contained natural water only ('Controls'), 2 contained natural water with Crassostrea gigas ('Oyster'), and 2 contained natural water with Atherina spp. ('Fish'). Abundances and biomasses of microorganisms (viruses, bacteria, phytoplankton, heterotrophic flagellates, and ciliates) were measured to estimate their contribution to the total microbial carbon biomass. Two MFW indices, the microbial autotroph: heterotroph C biomass ratio (A:H) structural index and the gross primary production: respiration ratio (GPP:R) functional index, were defined. In the Fish mesocosms, selective... |
| Tipo: Text |
Palavras-chave: Microbial food web; Virioplankton; Bacterioplankton; Phytoplankton; Protozooplankton; Crassostrea; Atherina; Autotrophy; Heterotrophy. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00284/39489/73675.pdf |
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| Trottet, Aurore; Leboulanger, Christophe; Vidussi, Francesca; Pete, Romain; Bouvy, Marc; Fouilland, Eric. |
| The importance of heterotrophic bacteria relative to phytoplankton in the uptake of ammonium and nitrate was studied in Mediterranean coastal waters (Thau Lagoon) during autumn, when the Mediterranean Sea received the greatest allochthonous nutrient loads. Specific inhibitors and size-fractionation methods were used in combination with isotopic N-15 tracers. NO3 (-) and NH4 (+) uptake was dominated by phytoplankton (60 % on average) during the study period, which included a flood event. Despite lower biomass specific NH4 (+) and NO3 uptake rates, free-living heterotrophic bacteria contributed significantly (> 30 %) to total microbial NH4 (+) and NO3 (-) uptake rates in low chlorophyll waters. Under these conditions, heterotrophic bacteria may be... |
| Tipo: Text |
Palavras-chave: Bacteria; Phytoplankton; Inhibitors; Size fractionation; Nitrogen uptake; Dissolved inorganic nitrogen. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00314/42497/41907.pdf |
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| Trombetta, Thomas; Vidussi, Francesca; Mas, Sébastien; Parin, David; Simier, Monique; Mostajir, Behzad. |
| Phytoplankton blooms are an important, widespread phenomenon in open oceans, coastal waters and freshwaters, supporting food webs and essential ecosystem services. Blooms are even more important in exploited coastal waters for maintaining high resource production. However, the environmental factors driving blooms in shallow productive coastal waters are still unclear, making it difficult to assess how environmental fluctuations influence bloom phenology and productivity. To gain insights into bloom phenology, Chl a fluorescence and meteorological and hydrological parameters were monitored at high-frequency (15 min) and nutrient concentrations and phytoplankton abundance and diversity, were monitored weekly in a typical Mediterranean shallow coastal system... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00488/60004/63240.pdf |
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| Soulié, Tanguy; Mas, Sébastien; Parin, David; Vidussi, Francesca; Mostajir, Behzad. |
| Understanding how aquatic ecosystems respond to perturbations has emerged as a crucial way to predict the future of these ecosystems and to assess their capacity to produce oxygen and store atmospheric carbon. In this context, in situ mesocosm experiments are a useful approach for simulating disturbances and observing changes in planktonic communities over time and under controlled conditions. Within mesocosm experiments, the estimation of fundamental parameters such as gross primary production (GPP), net community production (NCP), and respiration (R) allows the evaluation of planktonic metabolic responses to a perturbation. The continuous estimation of these metabolic parameters in real time and at high frequency is made possible by employing noninvasive... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00686/79762/82562.pdf |
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| Courboulès, Justine; Vidussi, Francesca; Soulié, Tanguy; Mas, Sébastien; Pecqueur, David; Mostajir, Behzad. |
| To investigate the responses of a natural microbial plankton community of coastal Mediterranean waters to warming, which are still poorly known, an in situ mesocosm experiment was carried out in Thau Lagoon during autumn 2018. Several microorganisms, including virio-, bacterio-, and phytoplankton < 10 µm in size, were monitored daily and analysed using flow cytometry for 19 consecutive days in six mesocosms. Three mesocosms (control) had the same natural water temperature as the lagoon, and the other three were warmed by + 3 °C in relation to the control temperature. The cytometric analyses revealed an unexpected community dominated by picophytoplanktonic cells, including Prochlorococcus-like and Picochlorum-like cells, which had not previously been... |
| Tipo: Text |
Palavras-chave: Pico- and nanophytoplankton; Bacterioplankton; Virus; Warming; In situ mesocosm; Thau lagoon. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00688/79979/82933.pdf |
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