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Soulié T, Vidussi F, Mas S, Mostajir B. Functional and structural responses of plankton communities toward consecutive experimental heatwaves in Mediterranean coastal waters. Sci Rep 2023; 13:8050. [PMID: 37198394 DOI: 10.1038/s41598-023-35311-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/16/2023] [Indexed: 05/19/2023] Open
Abstract
The frequency of marine heatwaves (HWs) is projected to increase in the Mediterranean Sea over the next decades. An in situ mesocosm experiment was performed in a Mediterranean lagoon for 33 days. Three mesocosms were used as controls following the natural temperature of the lagoon. In three others, two HWs of + 5 °C compared to the controls were applied from experimental day (d) 1 to d5 (HW1) and from d11 to d15 (HW2). High-frequency data of oxygen, chlorophyll-a (chl-a), temperature, salinity and light from sensors immersed in all mesocosms were used to calculate gross primary production (GPP), respiration (R) and phytoplankton growth (µ) and loss (L) rates. Nutrients and phytoplankton community structure from pigments were also analyzed. HW1 significantly increased GPP, R, chl-a, µ and L by 7 to 38%. HW2 shifted the system toward heterotrophy by only enhancing R. Thus, the effects of the first HW resulted in the attenuation of those of a second HW on phytoplankton processes, but not on community respiration, which was strongly regulated by temperature. In addition, natural phytoplankton succession from diatoms to haptophytes was altered by both HWs as cyanobacteria and chlorophytes were favored at the expense of haptophytes. These results indicate that HWs have pronounced effects on Mediterranean plankton communities.
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Affiliation(s)
- Tanguy Soulié
- MARBEC (MARine Biodiversity, Exploitation and Conservation), Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France.
| | - Francesca Vidussi
- MARBEC (MARine Biodiversity, Exploitation and Conservation), Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - Sébastien Mas
- MEDIMEER (MEDIterranean Platform for Marine Ecosystems Experimental Research), OSU OREME, CNRS, Univ Montpellier, IRD, INRAE, Sète, France
| | - Behzad Mostajir
- MARBEC (MARine Biodiversity, Exploitation and Conservation), Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France.
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Soulié T, Vidussi F, Courboulès J, Mas S, Mostajir B. Metabolic responses of plankton to warming during different productive seasons in coastal Mediterranean waters revealed by in situ mesocosm experiments. Sci Rep 2022; 12:9001. [PMID: 35637213 PMCID: PMC9151769 DOI: 10.1038/s41598-022-12744-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/16/2022] [Indexed: 11/28/2022] Open
Abstract
The response of coastal lagoon plankton communities to warming was studied during two in situ mesocosm experiments in spring and fall of 2018 in the Mediterranean. Phytoplankton biomass, gross primary production (GPP), community respiration (R), phytoplankton growth (µ), and loss (l) rates were estimated using high-frequency chlorophyll-a fluorescence and dissolved oxygen sensors, and daily sampling was used to evaluate the nutrient status and phytoplankton pigment functional groups. Warming strongly depressed the dominant phytoplankton functional groups, mainly the prymnesiophytes, diatoms (spring), and green flagellates (fall). It favored minor groups such as the dinoflagellates (spring) and diatoms (fall). In spring, warming depressed GPP and R by half; however, µ (+ 18%) and l (+ 37%) were enhanced. In contrast, both GPP and µ were enhanced by 21% and 28%, respectively, in fall, and no effects were observed for R and l. Warming strongly decreased phytoplankton biomass and oxygen production in spring, and enhanced them, to a lesser extent, in fall. This led to an overall loss of production over both seasons. This study improves understanding of the contrasting effects of warming during two productive seasons, which depend on plankton community composition and interactions between components and environmental conditions.
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Trombetta T, Vidussi F, Roques C, Mas S, Scotti M, Mostajir B. Co-occurrence networks reveal the central role of temperature in structuring the plankton community of the Thau Lagoon. Sci Rep 2021; 11:17675. [PMID: 34480057 PMCID: PMC8417261 DOI: 10.1038/s41598-021-97173-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 08/18/2021] [Indexed: 02/07/2023] Open
Abstract
To identify the environmental factors that drive plankton community composition and structure in coastal waters, a shallow northwestern Mediterranean lagoon was monitored from winter to spring in two contrasting years. The campaign was based on high-frequency recordings of hydrological and meteorological parameters and weekly samplings of nutrients and the plankton community. The collected data allowed the construction of correlation networks, which revealed that water temperature was the most important factor governing community composition, structure and succession at different trophic levels, suggesting its ubiquitous food web control. Temperature favoured phytoplanktonic flagellates (Cryptophyceae, Chrysophyceae, and Chlorophyceae) and ciliates during winter and early spring. In contrast, it favoured Bacillariophyceae, dinoflagellates, phytoplankton < 6 µm and aloricate Choreotrichida during spring. The secondary factors were light, which influenced phytoplankton, and wind, which may regulate turbidity and the nutrient supply from land or sediment, thus affecting benthic species such as Nitzschia sp. and Uronema sp. or salinity-tolerant species such as Prorocentrum sp. The central role of temperature in structuring the co-occurrence network suggests that future global warming could deeply modify plankton communities in shallow coastal zones, affecting whole-food web functioning.
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Affiliation(s)
- Thomas Trombetta
- grid.121334.60000 0001 2097 0141MARBEC (Marine Biodiversity, Exploitation and Conservation), Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - Francesca Vidussi
- grid.121334.60000 0001 2097 0141MARBEC (Marine Biodiversity, Exploitation and Conservation), Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - Cécile Roques
- grid.121334.60000 0001 2097 0141MARBEC (Marine Biodiversity, Exploitation and Conservation), Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - Sébastien Mas
- grid.121334.60000 0001 2097 0141MEDIMEER (Mediterranean Platform for Marine Ecosystems Experimental Research), OSU OREME, Univ Montpellier, CNRS, IRD, IRSTEA, Sète, France
| | - Marco Scotti
- grid.15649.3f0000 0000 9056 9663GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Behzad Mostajir
- grid.121334.60000 0001 2097 0141MARBEC (Marine Biodiversity, Exploitation and Conservation), Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
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Richard M, Rolland JL, Gueguen Y, de Lorgeril J, Pouzadoux J, Mostajir B, Bec B, Mas S, Parin D, Le Gall P, Mortreux S, Fiandrino A, Lagarde F, Messiaen G, Fortune M, Roque d'Orbcastel E. In situ characterisation of pathogen dynamics during a Pacific oyster mortality syndrome episode. Mar Environ Res 2021; 165:105251. [PMID: 33548594 DOI: 10.1016/j.marenvres.2020.105251] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 12/17/2020] [Accepted: 12/26/2020] [Indexed: 06/12/2023]
Abstract
Significant mortality of Crassostrea gigas juveniles is observed systematically every year worldwide. Pacific Oyster Mortality Syndrome (POMS) is caused by Ostreid Herpesvirus 1 (OsHV-1) infection leading to immune suppression, followed by bacteraemia caused by a consortium of opportunistic bacteria. Using an in-situ approach and pelagic chambers, our aim in this study was to identify pathogen dynamics in oyster flesh and in the water column during the course of a mortality episode in the Mediterranean Thau lagoon (France). OsHV-1 concentrations in oyster flesh increased before the first clinical symptoms of the disease appeared, reached maximum concentrations during the moribund phase and the mortality peak. The structure of the bacterial community associated with oyster flesh changed in favour of bacterial genera previously associated with oyster mortality including Vibrio, Arcobacter, Psychrobium, and Psychrilyobacter. During the oyster mortality episode, releases of OsHV-1 and opportunistic bacteria were observed, in succession, in the water surrounding the oyster lanterns. These releases may favour the spread of disease within oyster farms and potentially impact other marine species, thereby reducing marine biodiversity in shellfish farming areas.
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Affiliation(s)
- Marion Richard
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Sète, France.
| | - Jean Luc Rolland
- IHPE, Univ Montpellier, CNRS, Ifremer, UPVD, Montpellier, France
| | - Yannick Gueguen
- IHPE, Univ Montpellier, CNRS, Ifremer, UPVD, Montpellier, France
| | - Julien de Lorgeril
- IHPE, Univ Montpellier, CNRS, Ifremer, UPVD, Montpellier, France; Ifremer, IRD, Univ Nouvelle-Calédonie, Univ La Réunion, ENTROPIE, F-98800 Nouméa, Nouvelle-Calédonie, France
| | | | - Behzad Mostajir
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - Béatrice Bec
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - Sébastien Mas
- OSU-OREME, Univ Montpellier, CNRS, IRD, IRSTEA, Sète, France
| | - David Parin
- OSU-OREME, Univ Montpellier, CNRS, IRD, IRSTEA, Sète, France
| | - Patrik Le Gall
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Sète, France
| | - Serge Mortreux
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Sète, France
| | | | - Franck Lagarde
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Sète, France
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Trombetta T, Vidussi F, Roques C, Scotti M, Mostajir B. Marine Microbial Food Web Networks During Phytoplankton Bloom and Non-bloom Periods: Warming Favors Smaller Organism Interactions and Intensifies Trophic Cascade. Front Microbiol 2020; 11:502336. [PMID: 33193116 PMCID: PMC7644461 DOI: 10.3389/fmicb.2020.502336] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 10/02/2020] [Indexed: 01/17/2023] Open
Abstract
Microbial food web organisms are at the base of the functioning of pelagic ecosystems and support the whole marine food web. They are very reactive to environmental changes and their interactions are modified in response to different productive periods such as phytoplankton bloom and non-bloom as well as contrasted climatic years. To study ecological associations, identify potential interactions between microorganisms and study the structure of the microbial food web in coastal waters, a weekly monitoring was carried out in the Thau Lagoon on the French Mediterranean coast. The monitoring lasted from winter to late spring during two contrasting climatic years, a typical Mediterranean (2015) and a year with an extreme warm winter (2016). Correlation networks comprising 110 groups/taxa/species were constructed to characterize potential possible interactions between the microorganisms during bloom and non-bloom periods. Complex correlation networks during the bloom and dominated by negative intraguild correlations and positive correlations of phytoplankton with bacteria. Such pattern can be interpreted as a dominance of competition and mutualism. In contrast, correlation networks during the non-bloom period were less complex and mostly dominated by tintinnids associations with bacteria mostly referring to potential feeding on bacteria, which suggests a shift of biomass transfer from phytoplankton-dominated food webs during bloom to more bacterioplankton-based food webs during non-bloom. Inter-annual climatic conditions significantly modified the structure of microbial food webs. The warmer year favored relationships among smaller group/taxa/species at the expense of large phytoplankton and ciliates, possibly due to an intensification of the trophic cascade with a potential shift in energy circulation through microbial food web. Our study compares a typical Mediterranean spring with another mimicking the prospected intensification of global warming; if such consideration holds true, the dominance of future coastal marine ecosystems will be shifted from the highly productive herbivorous food web to the less productive microbial food web.
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Affiliation(s)
- Thomas Trombetta
- Marine Biodiversity, Exploitation and Conservation, Centre National de la Recherche Scientifique, Institut Français de Recherche pour l'Exploitation de la Mer, Institut de Recherche pour le Développement, University of Montpellier, Montpellier, France
| | - Francesca Vidussi
- Marine Biodiversity, Exploitation and Conservation, Centre National de la Recherche Scientifique, Institut Français de Recherche pour l'Exploitation de la Mer, Institut de Recherche pour le Développement, University of Montpellier, Montpellier, France
| | - Cécile Roques
- Marine Biodiversity, Exploitation and Conservation, Centre National de la Recherche Scientifique, Institut Français de Recherche pour l'Exploitation de la Mer, Institut de Recherche pour le Développement, University of Montpellier, Montpellier, France
| | - Marco Scotti
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Behzad Mostajir
- Marine Biodiversity, Exploitation and Conservation, Centre National de la Recherche Scientifique, Institut Français de Recherche pour l'Exploitation de la Mer, Institut de Recherche pour le Développement, University of Montpellier, Montpellier, France
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Trombetta T, Vidussi F, Mas S, Parin D, Simier M, Mostajir B. Water temperature drives phytoplankton blooms in coastal waters. PLoS One 2019; 14:e0214933. [PMID: 30951553 PMCID: PMC6450617 DOI: 10.1371/journal.pone.0214933] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 03/24/2019] [Indexed: 11/30/2022] Open
Abstract
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 (Thau Lagoon). This study was carried out from winter to late spring in two successive years with different climatic conditions: 2014/2015 was typical, but the winter of 2015/2016 was the warmest on record. Rising water temperature was the main driver of phytoplankton blooms. However, blooms were sometimes correlated with winds and sometimes correlated with salinity, suggesting nutrients were supplied by water transport via winds, saltier seawater intake, rain and water flow events. This finding indicates the joint role of these factors in determining the success of phytoplankton blooms. Furthermore, interannual variability showed that winter water temperature was higher in 2016 than in 2015, resulting in lower phytoplankton biomass accumulation in the following spring. Moreover, the phytoplankton abundances and diversity also changed: cyanobacteria (< 1 μm), picoeukaryotes (< 1 μm) and nanoeukaryotes (3–6 μm) increased to the detriment of larger phytoplankton such as diatoms. Water temperature is a key factor affecting phytoplankton bloom dynamics in shallow productive coastal waters and could become crucial with future global warming by modifying bloom phenology and changing phytoplankton community structure, in turn affecting the entire food web and ecosystem services.
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Affiliation(s)
- Thomas Trombetta
- MARBEC (Marine Biodiversity, Exploitation and Conservation), Centre National de la Recherche Scientifique, Université de Montpellier, Institut Français de Recherche pour l’Exploitation de la Mer, Institut de Recherche pour le Développement, Montpellier, France
- * E-mail:
| | - Francesca Vidussi
- MARBEC (Marine Biodiversity, Exploitation and Conservation), Centre National de la Recherche Scientifique, Université de Montpellier, Institut Français de Recherche pour l’Exploitation de la Mer, Institut de Recherche pour le Développement, Montpellier, France
| | - Sébastien Mas
- MEDIMEER (Mediterranean Platform for Marine Ecosystems Experimental Research), Observatoire de Recherche Méditerranéen de l’Environnement, Centre National de la Recherche Scientifique, Université de Montpellier, Institut de Recherche pour le Développement, Institut National de Recherche en Sciences et Technologies pour l’Environnement et l’Agriculture, Sète, France
| | - David Parin
- MEDIMEER (Mediterranean Platform for Marine Ecosystems Experimental Research), Observatoire de Recherche Méditerranéen de l’Environnement, Centre National de la Recherche Scientifique, Université de Montpellier, Institut de Recherche pour le Développement, Institut National de Recherche en Sciences et Technologies pour l’Environnement et l’Agriculture, Sète, France
| | - Monique Simier
- MARBEC (Marine Biodiversity, Exploitation and Conservation), Institut de Recherche pour le Développement, Centre National de la Recherche Scientifique, Université de Montpellier, Institut Français de Recherche pour l’Exploitation de la Mer, Sète, France
| | - Behzad Mostajir
- MARBEC (Marine Biodiversity, Exploitation and Conservation), Centre National de la Recherche Scientifique, Université de Montpellier, Institut Français de Recherche pour l’Exploitation de la Mer, Institut de Recherche pour le Développement, Montpellier, France
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Fouilland E, Trottet A, Alves-de-Souza C, Bonnet D, Bouvier T, Bouvy M, Boyer S, Guillou L, Hatey E, Jing H, Leboulanger C, Le Floc'h E, Liu H, Mas S, Mostajir B, Nouguier J, Pecqueur D, Rochelle-Newall E, Roques C, Salles C, Tournoud MG, Vasseur C, Vidussi F. Significant Change in Marine Plankton Structure and Carbon Production After the Addition of River Water in a Mesocosm Experiment. Microb Ecol 2017; 74:289-301. [PMID: 28303313 DOI: 10.1007/s00248-017-0962-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 03/02/2017] [Indexed: 06/06/2023]
Abstract
Rivers are known to be major contributors to eutrophication in marine coastal waters, but little is known on the short-term impact of freshwater surges on the structure and functioning of the marine plankton community. The effect of adding river water, reducing the salinity by 15 and 30%, on an autumn plankton community in a Mediterranean coastal lagoon (Thau Lagoon, France) was determined during a 6-day mesocosm experiment. Adding river water brought not only nutrients but also chlorophyceans that did not survive in the brackish mesocosm waters. The addition of water led to initial increases (days 1-2) in bacterial production as well as increases in the abundances of bacterioplankton and picoeukaryotes. After day 3, the increases were more significant for diatoms and dinoflagellates that were already present in the Thau Lagoon water (mainly Pseudo-nitzschia spp. group delicatissima and Prorocentrum triestinum) and other larger organisms (tintinnids, rotifers). At the same time, the abundances of bacterioplankton, cyanobacteria, and picoeukaryote fell, some nutrients (NH4+, SiO43-) returned to pre-input levels, and the plankton structure moved from a trophic food web based on secondary production to the accumulation of primary producers in the mesocosms with added river water. Our results also show that, after freshwater inputs, there is rapid emergence of plankton species that are potentially harmful to living organisms. This suggests that flash flood events may lead to sanitary issues, other than pathogens, in exploited marine areas.
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Affiliation(s)
- E Fouilland
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France.
| | - A Trottet
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
- DHI Water & Environment (S) Pte Ltd, 1 Cleantech loop #03-05 Clean Tech One, Singapore, 637141, Singapore
| | - C Alves-de-Souza
- Sorbonne Universités, Université Pierre et Marie Curie - Paris 6, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, CS90074, 29688, Roscoff cedex, France
- Laboratório de Ficologia, Departamento de Botânica, Museu Nacional/Universidade Federal do Rio de Janeiro, Quinta da Boa Vista, s/n, São Cristovão, Rio de Janeiro, RJ, 20940-040, Brazil
| | - D Bonnet
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - T Bouvier
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - M Bouvy
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - S Boyer
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - L Guillou
- Sorbonne Universités, Université Pierre et Marie Curie - Paris 6, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, CS90074, 29688, Roscoff cedex, France
| | - E Hatey
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - H Jing
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - C Leboulanger
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - E Le Floc'h
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - H Liu
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - S Mas
- UMS 3301Centre d'écologie marine expérimentale MEDIMEER, Université de Montpellier, CNRS, Station Marine, 2 rue des Chantiers, 34200, Sète, France
| | - B Mostajir
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - J Nouguier
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - D Pecqueur
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - E Rochelle-Newall
- UMR 7618 iEES-Paris (IRD-UPMC-CNRS-INRA-UDD-UPEC), UPMC, case 237, 4 place Jussieu, 75252, Paris cedex, France
| | - C Roques
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
| | - C Salles
- UMR 5569 Laboratoire HydroSciences (CNRS, IRD, UM), Université de Montpellier, case courrier 057, 34095, Montpellier cedex 5, France
| | - M-G Tournoud
- UMR 5569 Laboratoire HydroSciences (CNRS, IRD, UM), Université de Montpellier, case courrier 057, 34095, Montpellier cedex 5, France
| | - C Vasseur
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
- LOV-UPMC-CNRS, UMR 7093, Station zoologique, BP 28 06234, Villefranche-sur-mer, France
| | - F Vidussi
- UMR 9190 MARBEC Marine Biodiversity, Exploitation and Conservation, CNRS, IRD, IFREMER, Université de Montpellier, Montpellier & Sète, France
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Tsiola A, Pitta P, Fodelianakis S, Pete R, Magiopoulos I, Mara P, Psarra S, Tanaka T, Mostajir B. Nutrient Limitation in Surface Waters of the Oligotrophic Eastern Mediterranean Sea: an Enrichment Microcosm Experiment. Microb Ecol 2016; 71:575-588. [PMID: 26626911 DOI: 10.1007/s00248-015-0713-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 11/17/2015] [Indexed: 06/05/2023]
Abstract
The growth rates of planktonic microbes in the pelagic zone of the Eastern Mediterranean Sea are nutrient limited, but the type of limitation is still uncertain. During this study, we investigated the occurrence of N and P limitation among different groups of the prokaryotic and eukaryotic (pico-, nano-, and micro-) plankton using a microcosm experiment during stratified water column conditions in the Cretan Sea (Eastern Mediterranean). Microcosms were enriched with N and P (either solely or simultaneously), and the PO4 turnover time, prokaryotic heterotrophic activity, primary production, and the abundance of the different microbial components were measured. Flow cytometric and molecular fingerprint analyses showed that different heterotrophic prokaryotic groups were limited by different nutrients; total heterotrophic prokaryotic growth was limited by P, but only when both N and P were added, changes in community structure and cell size were detected. Phytoplankton were N and P co-limited, with autotrophic pico-eukaryotes being the exception as they increased even when only P was added after a 2-day time lag. The populations of Synechococcus and Prochlorococcus were highly competitive with each other; Prochlorococcus abundance increased during the first 2 days of P addition but kept increasing only when both N and P were added, whereas Synechococcus exhibited higher pigment content and increased in abundance 3 days after simultaneous N and P additions. Dinoflagellates also showed opportunistic behavior at simultaneous N and P additions, in contrast to diatoms and coccolithophores, which diminished in all incubations. High DNA content viruses, selective grazing, and the exhaustion of N sources probably controlled the populations of diatoms and coccolithophores.
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Affiliation(s)
- A Tsiola
- Institute of Oceanography, Hellenic Centre for Marine Research (HCMR), Ex American Base Gournes, P.O. Box 2214, 71003, Heraklion, Crete, Greece.
- Biology Department, Marine Ecology Laboratory, University of Crete, Heraklion, Crete, Greece.
| | - P Pitta
- Institute of Oceanography, Hellenic Centre for Marine Research (HCMR), Ex American Base Gournes, P.O. Box 2214, 71003, Heraklion, Crete, Greece
| | - S Fodelianakis
- Biology Department, Marine Ecology Laboratory, University of Crete, Heraklion, Crete, Greece
- King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
| | - R Pete
- Laboratoire d'Ecologie des Systèmes Marins Côtiers (ECOSYM), CNRS-Université Montpellier 2 & 1-Ifremer-IRD, Montpellier, France
| | - I Magiopoulos
- Institute of Oceanography, Hellenic Centre for Marine Research (HCMR), Ex American Base Gournes, P.O. Box 2214, 71003, Heraklion, Crete, Greece
- Biology Department, Marine Ecology Laboratory, University of Crete, Heraklion, Crete, Greece
| | - P Mara
- Chemistry Department, Environmental Chemical Processes Laboratory, University of Crete, Heraklion, Crete, Greece
| | - S Psarra
- Institute of Oceanography, Hellenic Centre for Marine Research (HCMR), Ex American Base Gournes, P.O. Box 2214, 71003, Heraklion, Crete, Greece
| | - T Tanaka
- INSU-CNRS, Laboratoire d'Océanographie de Villefranche, Villefranche sur Mer cedex, France
- Université Pierre et Marie Curie-Paris 6, Observatoire Océanologie de Villefranche, Villefranche sur Mer cedex, France
| | - B Mostajir
- Laboratoire d'Ecologie des Systèmes Marins Côtiers (ECOSYM), CNRS-Université Montpellier 2 & 1-Ifremer-IRD, Montpellier, France
- Centre d'Ecologie Marine Expérimentale MEDIMEER, Mediterranean Center for Marine Ecosystem Experimental Research, CNRS-Université Montpellier 2, Montpellier, Sète, France
- Marine Biodiversity, Exploitation and Conservation (MARBEC), UMR 9190, CNRS-Université de Montpellier-IFREMER-IRD, Montpellier, France
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9
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Sebastián M, Smith AF, González JM, Fredricks HF, Van Mooy B, Koblížek M, Brandsma J, Koster G, Mestre M, Mostajir B, Pitta P, Postle AD, Sánchez P, Gasol JM, Scanlan DJ, Chen Y. Lipid remodelling is a widespread strategy in marine heterotrophic bacteria upon phosphorus deficiency. ISME J 2016; 10:968-78. [PMID: 26565724 PMCID: PMC4796936 DOI: 10.1038/ismej.2015.172] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 08/10/2015] [Indexed: 11/25/2022]
Abstract
Upon phosphorus (P) deficiency, marine phytoplankton reduce their requirements for P by replacing membrane phospholipids with alternative non-phosphorus lipids. It was very recently demonstrated that a SAR11 isolate also shares this capability when phosphate starved in culture. Yet, the extent to which this process occurs in other marine heterotrophic bacteria and in the natural environment is unknown. Here, we demonstrate that the substitution of membrane phospholipids for a variety of non-phosphorus lipids is a conserved response to P deficiency among phylogenetically diverse marine heterotrophic bacteria, including members of the Alphaproteobacteria and Flavobacteria. By deletion mutagenesis and complementation in the model marine bacterium Phaeobacter sp. MED193 and heterologous expression in recombinant Escherichia coli, we confirm the roles of a phospholipase C (PlcP) and a glycosyltransferase in lipid remodelling. Analyses of the Global Ocean Sampling and Tara Oceans metagenome data sets demonstrate that PlcP is particularly abundant in areas characterized by low phosphate concentrations. Furthermore, we show that lipid remodelling occurs seasonally and responds to changing nutrient conditions in natural microbial communities from the Mediterranean Sea. Together, our results point to the key role of lipid substitution as an adaptive strategy enabling heterotrophic bacteria to thrive in the vast P-depleted areas of the ocean.
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Affiliation(s)
- Marta Sebastián
- Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC, Barcelona, Spain
| | | | - José M González
- Department of Microbiology, University of La Laguna, La Laguna, Spain
| | - Helen F Fredricks
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Benjamin Van Mooy
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Michal Koblížek
- Institute of Microbiology, Center Algatech, Třeboň, Czech Republic
| | - Joost Brandsma
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Grielof Koster
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Mireia Mestre
- Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC, Barcelona, Spain
| | - Behzad Mostajir
- Center of Marine Biodiversity, Exploitation and Conservation (MARBEC), UMR 9190, CNRS – Université de Montpellier – IRD – IFREMER, Place Eugène Bataillon, Université de Montpellier, Case 93, Montpellier, France
| | - Paraskevi Pitta
- Hellenic Centre for Marine Research, Oceanography Institute, Heraklion, Greece
| | - Anthony D Postle
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Pablo Sánchez
- Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC, Barcelona, Spain
| | - Josep M Gasol
- Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC, Barcelona, Spain
| | - David J Scanlan
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Yin Chen
- School of Life Sciences, University of Warwick, Coventry, UK
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10
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Alves-de-Souza C, Pecqueur D, Le Floc’h E, Mas S, Roques C, Mostajir B, Vidussi F, Velo-Suárez L, Sourisseau M, Fouilland E, Guillou L. Significance of plankton community structure and nutrient availability for the control of dinoflagellate blooms by parasites: a modeling approach. PLoS One 2015; 10:e0127623. [PMID: 26030411 PMCID: PMC4452582 DOI: 10.1371/journal.pone.0127623] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 04/16/2015] [Indexed: 11/18/2022] Open
Abstract
Dinoflagellate blooms are frequently observed under temporary eutrophication of coastal waters after heavy rains. Growth of these opportunistic microalgae is believed to be promoted by sudden input of nutrients and the absence or inefficiency of their natural enemies, such as grazers and parasites. Here, numerical simulations indicate that increasing nutrient availability not only promotes the formation of dinoflagellate blooms but can also stimulate their control by protozoan parasites. Moreover, high abundance of phytoplankton other than dinoflagellate hosts might have a significant dilution effect on the control of dinoflagellate blooms by parasites, either by resource competition with dinoflagellates (thus limiting the number of hosts available for infection) or by affecting numerical-functional responses of grazers that consume free-living parasite stages. These outcomes indicate that although both dinoflagellates and their protozoan parasites are directly affected by nutrient availability, the efficacy of the parasitic control of dinoflagellate blooms under temporary eutrophication depends strongly on the structure of the plankton community as a whole.
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Affiliation(s)
- Catharina Alves-de-Souza
- Laboratório de Ficologia, Departamento de Botânica, Museu Nacional/Universidade Federal do Rio de Janeiro, Quinta da Boa Vista S/N, São Cristóvão, Rio de Janeiro, RJ, Brasil
| | - David Pecqueur
- UMR 9190 MARBEC Center of Marine Biodiversity, Exploitation & Conservation, CNRS, UM, IRD, IFREMER, Université Montpellier, Place E. Bataillon, CC 093, Montpellier, France
| | - Emilie Le Floc’h
- UMR 9190 MARBEC Center of Marine Biodiversity, Exploitation & Conservation, CNRS, UM, IRD, IFREMER, Université Montpellier, Place E. Bataillon, CC 093, Montpellier, France
- UMS 3282 OSU OREME-MEDIMEER, IRD, UM, CNRS, SMEL, 2 rue des Chantiers, Sète, France
- UMR 9190 MARBEC Center of Marine Biodiversity, Exploitation & Conservation, CNRS, UM, IRD, IFREMER, SMEL, Sète, France
| | - Sébastien Mas
- UMS 3282 OSU OREME-MEDIMEER, IRD, UM, CNRS, SMEL, 2 rue des Chantiers, Sète, France
| | - Cécile Roques
- UMR 9190 MARBEC Center of Marine Biodiversity, Exploitation & Conservation, CNRS, UM, IRD, IFREMER, Université Montpellier, Place E. Bataillon, CC 093, Montpellier, France
| | - Behzad Mostajir
- UMR 9190 MARBEC Center of Marine Biodiversity, Exploitation & Conservation, CNRS, UM, IRD, IFREMER, Université Montpellier, Place E. Bataillon, CC 093, Montpellier, France
| | - Franscesca Vidussi
- UMR 9190 MARBEC Center of Marine Biodiversity, Exploitation & Conservation, CNRS, UM, IRD, IFREMER, Université Montpellier, Place E. Bataillon, CC 093, Montpellier, France
| | | | | | - Eric Fouilland
- UMR 9190 MARBEC Center of Marine Biodiversity, Exploitation & Conservation, CNRS, UM, IRD, IFREMER, SMEL, Sète, France
| | - Laure Guillou
- CNRS, UMR 7144 & Université Pierre et Marie Curie, Station Biologique de Roscoff, Place Georges Teissier, Roscoff, France
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11
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Moreau S, Mostajir B, Bélanger S, Schloss IR, Vancoppenolle M, Demers S, Ferreyra GA. Climate change enhances primary production in the western Antarctic Peninsula. Glob Chang Biol 2015; 21:2191-205. [PMID: 25626857 DOI: 10.1111/gcb.12878] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 12/09/2014] [Accepted: 01/15/2015] [Indexed: 05/22/2023]
Abstract
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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Affiliation(s)
- Sébastien Moreau
- Georges Lemaître Centre for Earth and Climate Research, Earth and Life Institute, Université catholique de Louvain, Louvain-La-Neuve, Belgium; Institut des sciences de la mer de Rimouski (ISMER), Université du Québec à Rimouski (UQAR), 310 allée des Ursulines, Rimouski, QC, G5L 3A1, Canada
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12
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Fouilland E, Tolosa I, Bonnet D, Bouvier C, Bouvier T, Bouvy M, Got P, Le Floc'h E, Mostajir B, Roques C, Sempéré R, Sime-Ngando T, Vidussi F. Bacterial carbon dependence on freshly produced phytoplankton exudates under different nutrient availability and grazing pressure conditions in coastal marine waters. FEMS Microbiol Ecol 2013; 87:757-69. [DOI: 10.1111/1574-6941.12262] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Eric Fouilland
- Ecologie des Systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1); Sète France
- Station Méditerranéenne de l'Environnement Littoral; Sète France
- Université Montpellier 2; Montpellier France
| | - Imma Tolosa
- International Atomic Energy Agency- Environment Laboratories; Monaco Monaco
| | - Delphine Bonnet
- Ecologie des Systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1); Sète France
- Université Montpellier 2; Montpellier France
| | - Corinne Bouvier
- Ecologie des Systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1); Sète France
- Université Montpellier 2; Montpellier France
| | - Thierry Bouvier
- Ecologie des Systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1); Sète France
- Université Montpellier 2; Montpellier France
| | - Marc Bouvy
- Ecologie des Systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1); Sète France
- Université Montpellier 2; Montpellier France
| | - Patrice Got
- Ecologie des Systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1); Sète France
- Université Montpellier 2; Montpellier France
| | - Emilie Le Floc'h
- Ecologie des Systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1); Sète France
- Station Méditerranéenne de l'Environnement Littoral; Sète France
- Université Montpellier 2; Montpellier France
- Centre d'écologie marine expérimentale MEDIMEER (Mediterranean Center for Marine Ecosystem Experimental Research) UMS 3301 (Université Montpellier 2, CNRS); Station Méditerranéenne de l'Environnement Littoral; Sète France
| | - Behzad Mostajir
- Ecologie des Systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1); Sète France
- Université Montpellier 2; Montpellier France
- Centre d'écologie marine expérimentale MEDIMEER (Mediterranean Center for Marine Ecosystem Experimental Research) UMS 3301 (Université Montpellier 2, CNRS); Station Méditerranéenne de l'Environnement Littoral; Sète France
| | - Cécile Roques
- Ecologie des Systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1); Sète France
- Université Montpellier 2; Montpellier France
| | - Richard Sempéré
- Aix-Marseille Université; Université du Sud Toulon-Var; CNRS/INSU, IRD; Mediterranean Institute of Oceanography (MIO) UM 110; Marseille France
| | - Télesphore Sime-Ngando
- Laboratoire Microorganismes: Génome et Environnement (LMGE); UMR CNRS 6023; Clermont Université Blaise Pascal; Aubière France
| | - Francesca Vidussi
- Ecologie des Systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1); Sète France
- Université Montpellier 2; Montpellier France
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13
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Domaizon I, Lepère C, Debroas D, Bouvy M, Ghiglione JF, Jacquet S, Bettarel Y, Bouvier C, Torréton JP, Vidussi F, Mostajir B, Kirkham A, Lefloc'h E, Fouilland E, Montanié H, Bouvier T. Short-term responses of unicellular planktonic eukaryotes to increases in temperature and UVB radiation. BMC Microbiol 2012; 12:202. [PMID: 22966751 PMCID: PMC3478981 DOI: 10.1186/1471-2180-12-202] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 08/27/2012] [Indexed: 11/18/2022] Open
Abstract
Background Small size eukaryotes play a fundamental role in the functioning of coastal ecosystems, however, the way in which these micro-organisms respond to combined effects of water temperature, UVB radiations (UVBR) and nutrient availability is still poorly investigated. Results We coupled molecular tools (18S rRNA gene sequencing and fingerprinting) with microscope-based identification and counting to experimentally investigate the short-term responses of small eukaryotes (<6 μm; from a coastal Mediterranean lagoon) to a warming treatment (+3°C) and UVB radiation increases (+20%) at two different nutrient levels. Interestingly, the increase in temperature resulted in higher pigmented eukaryotes abundances and in community structure changes clearly illustrated by molecular analyses. For most of the phylogenetic groups, some rearrangements occurred at the OTUs level even when their relative proportion (microscope counting) did not change significantly. Temperature explained almost 20% of the total variance of the small eukaryote community structure (while UVB explained only 8.4%). However, complex cumulative effects were detected. Some antagonistic or non additive effects were detected between temperature and nutrients, especially for Dinophyceae and Cryptophyceae. Conclusions This multifactorial experiment highlights the potential impacts, over short time scales, of changing environmental factors on the structure of various functional groups like small primary producers, parasites and saprotrophs which, in response, can modify energy flow in the planktonic food webs.
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14
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Vasseur C, Bougaran G, Garnier M, Hamelin J, Leboulanger C, Le Chevanton M, Mostajir B, Sialve B, Steyer JP, Fouilland E. Carbon conversion efficiency and population dynamics of a marine algae-bacteria consortium growing on simplified synthetic digestate: first step in a bioprocess coupling algal production and anaerobic digestion. Bioresour Technol 2012; 119:79-87. [PMID: 22728186 DOI: 10.1016/j.biortech.2012.05.128] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 05/25/2012] [Accepted: 05/26/2012] [Indexed: 06/01/2023]
Abstract
Association of microalgae culture and anaerobic digestion seems a promising technology for sustainable algal biomass and biogas production. The use of digestates for sustaining the growth of microalgae reduces the costs and the environmental impacts associated with the substantial algal nutrient requirements. A natural marine algae-bacteria consortium was selected by growing on a medium containing macro nutrients (ammonia, phosphate and acetate) specific of a digestate, and was submitted to a factorial experimental design with different levels of temperature, light and pH. The microalgal consortium reached a maximum C conversion efficiency (i.e. ratio between carbon content produced and carbon supplied through light photosynthetic C conversion and acetate) of 3.6%. The presence of bacteria increased this maximum C conversion efficiency up to 6.3%. The associated bacterial community was considered beneficial to the total biomass production by recycling the carbon lost during photosynthesis and assimilating organic by-products from anaerobic digestion.
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Affiliation(s)
- Christophe Vasseur
- Laboratoire Ecologie des systèmes Marins côtiers UMR 5119 ECOSYM (Université Montpellier 2, CNRS, IRD, IFREMER, Université Montpellier 1), SMEL, 2 rue des Chantiers, Sète F-34200, France
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15
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Sucré E, Vidussi F, Mostajir B, Charmantier G, Lorin-Nebel C. Impact of ultraviolet-B radiation on planktonic fish larvae: alteration of the osmoregulatory function. Aquat Toxicol 2012; 109:194-201. [PMID: 22018917 DOI: 10.1016/j.aquatox.2011.09.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 09/26/2011] [Accepted: 09/28/2011] [Indexed: 05/31/2023]
Abstract
Coastal marine ecosystems are submitted to variations of several abiotic and biotic parameters, some of them related to global change. Among them the ultraviolet-B (UV-B) radiation (UVBR: 280-320 nm) may strongly impact planktonic fish larvae. The consequences of an increase of UVBR on the osmoregulatory function of Dicentrarchus labrax larvae have been investigated in this study. In young larvae of D. labrax, as in other teleosts, osmoregulation depends on tegumentary ion transporting cells, or ionocytes, mainly located on the skin of the trunk and of the yolk sac. As early D. labrax larvae passively drift in the top water column, ionocytes are exposed to solar radiation. The effect of UVBR on larval osmoregulation in seawater was evaluated through nanoosmometric measurements of the blood osmolality after exposure to different UV-B treatments. A loss of osmoregulatory capability occured in larvae after 2 days of low (50 μWcm(-2): 4 h L/20 h D) and medium (80 μWcm(-2): 4 h L/20 h D) UVBR exposure. Compared to control larvae kept in the darkness, a significant increase in blood osmolality, abnormal behavior and high mortalities were detected in larvae exposed to UVBR from 2 days on. At the cellular level, an important decrease in abundance of tegumentary ionocytes and mucous cells was observed after 2 days of exposure to UVBR. In the ionocytes, two major osmoeffectors were immunolocalized, the Na+/K(+)-ATPase and the Na+/K+/2Cl- cotransporter. Compared to controls, the fluorescent immunostaining was lower in UVBR-exposed larvae. We hypothesize that the impaired osmoregulation in UVBR-exposed larvae originates from the lower number of tegumentary ionocytes and mucous cells. This alteration of the osmoregulatory function could negatively impact the survival of young larvae at the surface water exposed to UVBR.
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Affiliation(s)
- Elliott Sucré
- AEO Team (Adaptation Ecophysiologique et Ontogenèse), UMR 5119 Ecosym UM2, CNRS, IRD, Ifremer, UM1, Université Montpellier 2, cc092, Pl. Eugène Bataillon, 34095 Montpellier, Cx 05, France.
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16
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Fouilland E, Mostajir B. Complementary support for the new ecological concept of ‘bacterial independence on contemporary phytoplankton production’ in oceanic waters. FEMS Microbiol Ecol 2011. [DOI: 10.1111/j.1574-6941.2011.01170.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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17
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Bouvy M, Bettarel Y, Bouvier C, Domaizon I, Jacquet S, Le Floc'h E, Montanié H, Mostajir B, Sime-Ngando T, Torréton JP, Vidussi F, Bouvier T. Trophic interactions between viruses, bacteria and nanoflagellates under various nutrient conditions and simulated climate change. Environ Microbiol 2011; 13:1842-57. [DOI: 10.1111/j.1462-2920.2011.02498.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Fouilland E, Mostajir B. Revisited phytoplanktonic carbon dependency of heterotrophic bacteria in freshwaters, transitional, coastal and oceanic waters. FEMS Microbiol Ecol 2010. [PMID: 20491928 DOI: 10.1111/j.1574‐6941.2010.00896.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Positive relationships between heterotrophic bacteria and particulate phytoplankton production (respectively, BP and PPP) have been reported for several areas, suggesting that material produced by phytoplankton was a major substrate for bacterial growth. Since then, thousands of simultaneous measurements of both PPP and BP have been performed. A review of these data showed that BP may exceed PPP considerably (median ranged between 132% and 484%) in all aquatic systems with the lowest PPP. In oceanic waters, BP did not seem to be temporally synchronized with PPP and the median BP : PPP ratio is 15% with moderate PPP, but the immediate bacterial carbon (C) demand (including bacterial respiration) was greater than the corresponding total primary production (i.e. dissolved and particulate primary production) for >80% of both volumetric and areal datasets. In freshwaters, the strong covariation observed between BP and PPP seemed mainly due to a common response to sudden nutrient inputs into enclosed systems, leading to a similar range of production rates and temporal synchronicities. Indeed, phytoplankton exudates contributed directly to only 32% (median) of BP when C-tracking experiments were performed in freshwaters. Therefore, because direct C dependency of bacteria on phytoplankton is questionable, other C sources might be more significant for bacterial growth.
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Affiliation(s)
- Eric Fouilland
- Laboratoire Ecosystèmes lagunaires, ECOLAG, UMR 5119 (CNRS, Université Montpellier 2, IFREMER, IRD), Montpellier and Sète, France.
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19
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Fouilland E, Mostajir B. Revisited phytoplanktonic carbon dependency of heterotrophic bacteria in freshwaters, transitional, coastal and oceanic waters. FEMS Microbiol Ecol 2010; 73:419-29. [DOI: 10.1111/j.1574-6941.2010.00896.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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20
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Mas S, Roy S, Blouin F, Mostajir B, Therriault JC, Nozais C, Demers S. DIEL VARIATIONS IN OPTICAL PROPERTIES OF IMANTONIA ROTUNDA (HAPTOPHYCEAE) AND THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE) EXPOSED TO DIFFERENT IRRADIANCE LEVELS(1). J Phycol 2008; 44:551-563. [PMID: 27041415 DOI: 10.1111/j.1529-8817.2008.00501.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Diel variations of cellular optical properties were examined for cultures of the haptophyte Imantonia rotunda N. Reynolds and the diatom Thalassiosira pseudonana (Hust.) Hasle et Heimdal grown under a 14:10 light:dark (L:D) cycle and transferred from 100 μmol photons · m(-2) · s(-1) to higher irradiances of 250 and 500 μmol photons · m(-2) · s(-1) . Cell volume and abundance, phytoplankton absorption coefficients, flow-cytometric light scattering and chl fluorescence, and pigment composition were measured every 2 h over a 24 h period. Results showed that cell division was more synchronous for I. rotunda than for T. pseudonana. Several variables exhibited diel variability with an amplitude >100%, notably mean cell volume for the haptophyte and photoprotective carotenoids for both species, while optical properties such as flow-cytometric scattering and chl a-specific phytoplankton absorption generally showed <50% diel variability. Increased irradiance induced changes in pigments (both species) and mean cell volume (for the diatom) and amplified diel variability for most variables. This increase in amplitude is larger for pigments (factor of 2 or more, notably for cellular photoprotective carotenoid content in I. rotunda and for photosynthetic pigments in T. pseudonana) than for optical properties (a factor of 1.5 for chl a-specific absorption, at 440 nm, in I. rotunda and a factor of 2 for the absorption cross-section and the chl a-specific scattering in T. pseudonana). Consequently, diel changes in optical properties and pigmentation associated with the L:D cycle and amplified by concurrent changes in irradiance likely contribute significantly to the variability in optical properties observed in biooptical field studies.
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Affiliation(s)
- Sébastien Mas
- Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, CanadaCNRS-GDR 2476 Réseaux Trophiques Aquatiques et UMR 5119 Ecosystèmes Lagunaires, CNRS/Université Montpellier II, Case 093, 34095 Montpellier Cedex 5, FranceInstitut Maurice-Lamontagne, Ministère des Pêches et des Océans, 850 route de la Mer, Mont-Joli, Québec G5H 3Z4, CanadaInstitut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, Canada
| | - Suzanne Roy
- Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, CanadaCNRS-GDR 2476 Réseaux Trophiques Aquatiques et UMR 5119 Ecosystèmes Lagunaires, CNRS/Université Montpellier II, Case 093, 34095 Montpellier Cedex 5, FranceInstitut Maurice-Lamontagne, Ministère des Pêches et des Océans, 850 route de la Mer, Mont-Joli, Québec G5H 3Z4, CanadaInstitut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, Canada
| | - Frédérick Blouin
- Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, CanadaCNRS-GDR 2476 Réseaux Trophiques Aquatiques et UMR 5119 Ecosystèmes Lagunaires, CNRS/Université Montpellier II, Case 093, 34095 Montpellier Cedex 5, FranceInstitut Maurice-Lamontagne, Ministère des Pêches et des Océans, 850 route de la Mer, Mont-Joli, Québec G5H 3Z4, CanadaInstitut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, Canada
| | - Behzad Mostajir
- Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, CanadaCNRS-GDR 2476 Réseaux Trophiques Aquatiques et UMR 5119 Ecosystèmes Lagunaires, CNRS/Université Montpellier II, Case 093, 34095 Montpellier Cedex 5, FranceInstitut Maurice-Lamontagne, Ministère des Pêches et des Océans, 850 route de la Mer, Mont-Joli, Québec G5H 3Z4, CanadaInstitut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, Canada
| | - Jean-Claude Therriault
- Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, CanadaCNRS-GDR 2476 Réseaux Trophiques Aquatiques et UMR 5119 Ecosystèmes Lagunaires, CNRS/Université Montpellier II, Case 093, 34095 Montpellier Cedex 5, FranceInstitut Maurice-Lamontagne, Ministère des Pêches et des Océans, 850 route de la Mer, Mont-Joli, Québec G5H 3Z4, CanadaInstitut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, Canada
| | - Christian Nozais
- Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, CanadaCNRS-GDR 2476 Réseaux Trophiques Aquatiques et UMR 5119 Ecosystèmes Lagunaires, CNRS/Université Montpellier II, Case 093, 34095 Montpellier Cedex 5, FranceInstitut Maurice-Lamontagne, Ministère des Pêches et des Océans, 850 route de la Mer, Mont-Joli, Québec G5H 3Z4, CanadaInstitut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, Canada
| | - Serge Demers
- Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, CanadaCNRS-GDR 2476 Réseaux Trophiques Aquatiques et UMR 5119 Ecosystèmes Lagunaires, CNRS/Université Montpellier II, Case 093, 34095 Montpellier Cedex 5, FranceInstitut Maurice-Lamontagne, Ministère des Pêches et des Océans, 850 route de la Mer, Mont-Joli, Québec G5H 3Z4, CanadaInstitut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L3A1, Canada
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Momo F, Ferrero E, Eöry M, Esusy M, Iribarren J, Ferreyra G, Schloss I, Mostajir B, Demers S. The Whole Is More Than the Sum of Its Parts: Modeling Community-Level Effects of UVR in Marine Ecosystems. Photochem Photobiol 2006; 82:903-8. [PMID: 17205623 DOI: 10.1562/2005-09-30-ra-706] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The effect of UVB radiation (UVBR, 290-320 nm) on the dynamics of the lower levels of the marine plankton community was modeled. The model was built using differential equations and shows a good fit to experimental data collected in mesocosms (defined as large enclosures of 1500 L filled with natural marine waters). Some unexpected results appear to be possible by indirect effects in prey (bacteria, phytoplankton and heterotrophic flagellates). In particular, apparent competition appears between small phytoplankton and bacteria. This effect is caused by a shared predator (ciliates). Another remarkable effect is an increase in bacteria and flagellates populations due to enhanced UVBR. This effect is similar to that observed under mesocosm experimental conditions and is related to the decrease of predation due to the direct damage to predators (ciliates) by UVBR. The effect of UVBR changing interaction coefficients may be dramatic on the community structure, producing big changes in equilibrium populations, as demonstrated by sensitivity analysis of the model. In order to generalize these results to field conditions it will be necessary to increase model complexity and include extra organic mater sources, mixing and sinking effects and predation by large zooplankton. This work shows that UVBR may produce community global responses that are consequence of both direct and indirect effects among populations.
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Affiliation(s)
- Fernando Momo
- Universidad Nacional de General Sarmiento, Instituto de Ciencias, Los Polvorines, Argentina.
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Ferreyra GA, Mostajir B, Schloss IR, Chatila K, Ferrario ME, Sargian P, Roy S, Prod'homme J, Demers S. Ultraviolet-B Radiation Effects on the Structure and Function of Lower Trophic Levels of the Marine Planktonic Food Web. Photochem Photobiol 2006; 82:887-97. [PMID: 17205621 DOI: 10.1562/2006-02-23-ra-810] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The impact of UV-B radiation (UVBR; 280-320 nm) on lower levels of a natural plankton assemblage (bacteria, phytoplankton and microzooplankton) from the St. Lawrence Estuary was studied during 9 days using several immersed outdoor mesocosms. Two exposure treatments were used in triplicate mesocosms: natural UVBR (N treatment, considered as the control treatment) and lamp-enhanced UVBR (H treatment, simulating 60% depletion of the ozone layer). A phytoplankton bloom developed after day 3, but no significant differences were found between treatments during the entire experiment for phytoplankton biomass (chlorophyll a and cell carbon) nor for phytoplankton cell abundances from flow cytometry and optical microscopy of three phytoplankton size classes (picoplankton, nanoplankton and microplankton). In contrast, bacterial abundances showed significantly higher values in the H treatment, attributed to a decrease in predation pressure due to a dramatic reduction in ciliate biomass (approximately 70-80%) in the H treatment relative to the N treatment. The most abundant ciliate species were Strombidinium sp., Prorodon ovum and Tintinnopsis sp.; all showed significantly lower abundances under the H treatment. P. ovum was the less-affected species (50% reduction in the H treatment compared with that of the N control), contrasting with approximately 90% for the other ones. Total specific phytoplanktonic and bacterial production were not affected by enhanced UVBR. However, both the ratio of primary to bacterial biomass and production decreased markedly under the H treatment. In contrast, the ratio of phytoplankton to bacterial plus ciliate carbon biomass showed an opposite trend than the previous results, with higher values in the H treatment at the end of the experiment. These results are explained by the changes in the ciliate biomass and suggest that UVBR can alter the structure of the lower levels of the planktonic community by selectively affecting key species. On the other hand, linearity between particulate organic carbon (POC) and estimated planktonic carbon was lost during the postbloom period in both treatments. On the basis of previous studies, our results can be attributed to the aggregation of carbon released by cells to the water column in the form of transparent exopolymer particles (TEPs) under nutrient limiting conditions. Unexpectedly, POC during such a period was higher in the H treatment than in controls. We hypothesize a decrease in the ingestion of TEPs by ciliates, in coincidence with increased DOC release by phytoplankton cells under enhanced UVBR. The consequences of such results for the carbon cycle in the ocean are discussed.
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Affiliation(s)
- Gustavo A Ferreyra
- Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 Allée des Ursulines, Canada G5L 3A1.
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Belzile C, Demers S, Ferreyra GA, Schloss I, Nozais C, Lacoste K, Mostajir B, Roy S, Gosselin M, Pelletier E, Gianesella SMF, Vernet M. UV Effects on Marine Planktonic Food Webs: A Synthesis of Results from Mesocosm Studies. Photochem Photobiol 2006; 82:850-6. [PMID: 16555926 DOI: 10.1562/2005-09-27-ra-699] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
UV irradiance has a broad range of effects on marine planktonic organisms. Direct and indirect effects on individual organisms have complex impacts on food-web structure and dynamics, with implications for carbon and nutrient cycling. Mesocosm experiments are well suited for the study of such complex interrelationships. Mesocosms offer the possibility to conduct well-controlled experiments with intact planktonic communities in physical, chemical and light conditions mimicking those of the natural environment. In allowing the manipulation of UV intensities and light spectral composition, the experimental mesocosm approach has proven to be especially useful in assessing the impacts at the community level. This review of mesocosm studies shows that, although a UV increase even well above natural intensities often has subtle effects on bulk biomass (carbon and chlorophyll), it can significantly impact the food-web structure because of different sensitivity to UV among planktonic organisms. Given the complexity of UV impacts, as evidenced by results of mesocosm studies, interactions between UV and changing environmental conditions (e.g. eutrophication and climate change) are likely to have significant effects on the function of marine ecosystems.
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Affiliation(s)
- Claude Belzile
- Institut des Sciences de la Mer de Rimouski, Université du Québec à Rimouski, Canada.
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Sargian P, Pelletier E, Mostajir B, Ferreyra GA, Demers S. TBT toxicity on a natural planktonic assemblage exposed to enhanced ultraviolet-B radiation. Aquat Toxicol 2005; 73:299-314. [PMID: 15869812 DOI: 10.1016/j.aquatox.2005.03.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2004] [Revised: 02/22/2005] [Accepted: 03/16/2005] [Indexed: 05/02/2023]
Abstract
A microcosm approach was designed to study the combined effects of tributyltin (TBT) from antifouling paints and ultraviolet-B radiation (UVBR: 280-320 nm), on a natural planktonic assemblage (<150 microm) isolated from the St. Lawrence Estuary at the end of the springtime. Microcosms (9l, cylindrical Teflon bags, 75 cm heightx25 cm width) were immersed in the water column of mesocosms (1800 l, polyethylene bags, 2.3 m depth) and exposed to two different UVBR regimes: natural ambient UVBR (NUVBR), and enhanced level of UVBR (HUVBR). During consecutive 5 days, effects of TBT (120 ng l -1) and enhanced UVBR (giving a biologically weighted UVBR 2.15-fold higher than natural light condition) were monitored in the samples coming from following treatments: (i) NUVBR light condition without TBT (NUVBR), (ii) NUVBR light condition with TBT-added (NUVBR+TBT), (iii) HUVBR light condition without TBT (HUVBR) and (iv) HUVBR light condition with TBT-added (HUVBR+TBT). Each treatment was conducted in triplicate microcosms. Different parameters were then measured during 5 days, including TBT analysis, bacterial abundance and productivity, phytoplankton abundance, cellular characteristics and growth rates, as well as in vivo chlorophyll a (Chl a) fluorescence. Following TBT addition (NUVBR+TBT treatment), Chl a concentrations never exceeded 1 microg l-1 whereas final values as high as 54 microg l-1 were observed in TBT-free treatments (NUVBR and HUVBR). TBT addition resulted also in the lost of fluorescence signal of the maximum efficiency of the photosystem II in phytoplankton assemblage. TBT toxicity caused on phytoplankton <20 microm an increase of mean cell size and changes in shape reflected a drastic disturbance of the cell cycle leading to an inhibition of the apparent growth rate. These negative effects of TBT resulted in a final abundance of phytoplankton <20 microm of 591+/-35 cells ml-1 in NUVBR+TBT relative to NUVBR treatment (i.e., 31,846+/-312 cells ml-1). Moreover, when cells were submitted to TBT under enhanced UVBR (HUVBR+TBT treatment), final abundance of phytoplankton <20 microm was only 182+/-90 cells ml-1, with a significant interaction between TBT and UVBR during the last 2 days of the experiment. The same type of interaction was also observed for bacterial abundance in NUVBR+TBT and HUVBR+TBT with stimulation of 226 and of 403%, respectively due to TBT addition relative to NUVBR treatment. When considering bacterial productivity, TBT addition resulted in an inhibition of 32%, and this inhibition was significantly more pronounced under dual stresses (i.e., 77% in HUVBR+TBT). These results clearly demonstrate that the combination of TBT and UVBR stresses have synergistic effects affecting the first trophic levels of the marine food web.
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Affiliation(s)
- Peggy Sargian
- Institut des Sciences de la Mer de Rimouski (ISMER), Université du Québec à Rimouski, 310, Allée des Ursulines, Rimouski, Que., Canada G5L 3A1.
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Chatila K, Demers S, Mostajir B, Gosselin M, Chanut JP, Monfort P, Bird D. The Responses of a Natural Bacterioplankton Community to Different Levels of Ultraviolet-B Radiation: A Food Web Perspective. Microb Ecol 2001; 41:56-68. [PMID: 11252164 DOI: 10.1007/s002480000042] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/1999] [Accepted: 03/01/2000] [Indexed: 05/23/2023]
Abstract
With the continuing increase of ultraviolet-B radiation (UVBR: 280-320 nm) fluxes toward the Earth's surface, there is concern regarding a possible negative impact on heterotrophic bacterioplankton. The effects of enhanced UVBR on a natural bacterioplankton community were studied during a 7-day experiment conducted in mesocosms (1500 L). Four light regimes were tested: natural light, 280 to 313 nm excluded UVBR, and two levels of UVBR enhancement. During the first 3 days of the experiment characterized by high inorganic nutrient concentrations (nitrates > 1 µmol L-1 and ammonium > 0.1 µmol L-l), UVBR had no effect on both bacterial abundances and activities. From day 4 to the end of the experiment, nitrate concentrations remained low (
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Affiliation(s)
- K. Chatila
- Groupe de Recherche en Environnement Côtier, Institut des sciences de la mer de Rimouski (ISMER), Université du Québec à Rimouski, 310-Allée des Ursulines, Rimouski (Québec), G5L 3A1, Canada
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Fauchot J, Gosselin M, Levasseur M, Mostajir B, Belzile C, Demers S, Roy S, Villegas PZ. INFLUENCE OF UV-B RADIATION ON NITROGEN UTILIZATION BY A NATURAL ASSEMBLAGE OF PHYTOPLANKTON. J Phycol 2000; 36:484-496. [PMID: 29544011 DOI: 10.1046/j.1529-8817.2000.99011.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A 7-day mesocosm experiment was conducted in July 1996 to investigate the effects of ambient UV-B radiation (UVBR) exclusion and two UVBR enhancements above ambient levels on NO3- , NH4+ and urea utilization in a natural plankton community (<240 μm) from the Lower St. Lawrence Estuary. The phytoplankton community was dominated by diatoms during the first 3 days and, afterward, by flagellates and dinoflagellates. The results of 4-h incubations just below the water surface show that, compared with ambient UVBR conditions, UVBR exclusion generally increased NO3- , NH4+ , and urea uptakes. During the last 4 days of the experiment, the percent increase in the specific uptake rate of urea under excluded UVBR conditions varied between 17% and 130% and was a linear function of the ambient UVBR dose removed. During the first 3 days, the phytoplankton community dominated by diatoms was able to withstand UVBR enhancements without any perceptible effect on nitrogen uptake. However, during the post-diatom bloom period, UVBR enhancements resulted in decreases in NO3- , NH4+ , and urea uptake compared with ambient UVBR conditions. The reduction of urea uptake under UVBR enhancements during the last 3 days varied between 23% and 64% and was linearly related to the enhanced UVBR dose. However, the different UVBR treatments did not affect the internal organic nitrogen composition (internal urea, free amino acids, and proteins) of the phytoplankton community experiencing vertical mixing in the mesocosms. The discrepancy between short-term uptake measurements at the surface and long-term effects in the mesocosms emphasizes the importance of vertical mixing on UVBR effects in natural ecosystems. This suggests that an increase in ambient UVBR would have a minimal effect on nitrogen utilization by natural phytoplankton assemblages if these are vertically mixed.
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Affiliation(s)
- Juliette Fauchot
- Institut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 CanadaInstitut Maurice Lamontagne, Ministère des Pêches et des Océans, C.P. 1000, Mont-Joli, Québec, G5H 3Z4 CanadaInstitut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 Canada
| | - Michel Gosselin
- Institut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 CanadaInstitut Maurice Lamontagne, Ministère des Pêches et des Océans, C.P. 1000, Mont-Joli, Québec, G5H 3Z4 CanadaInstitut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 Canada
| | - Maurice Levasseur
- Institut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 CanadaInstitut Maurice Lamontagne, Ministère des Pêches et des Océans, C.P. 1000, Mont-Joli, Québec, G5H 3Z4 CanadaInstitut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 Canada
| | - Behzad Mostajir
- Institut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 CanadaInstitut Maurice Lamontagne, Ministère des Pêches et des Océans, C.P. 1000, Mont-Joli, Québec, G5H 3Z4 CanadaInstitut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 Canada
| | - Claude Belzile
- Institut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 CanadaInstitut Maurice Lamontagne, Ministère des Pêches et des Océans, C.P. 1000, Mont-Joli, Québec, G5H 3Z4 CanadaInstitut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 Canada
| | - Serge Demers
- Institut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 CanadaInstitut Maurice Lamontagne, Ministère des Pêches et des Océans, C.P. 1000, Mont-Joli, Québec, G5H 3Z4 CanadaInstitut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 Canada
| | - Suzanne Roy
- Institut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 CanadaInstitut Maurice Lamontagne, Ministère des Pêches et des Océans, C.P. 1000, Mont-Joli, Québec, G5H 3Z4 CanadaInstitut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 Canada
| | - Piedad Zulema Villegas
- Institut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 CanadaInstitut Maurice Lamontagne, Ministère des Pêches et des Océans, C.P. 1000, Mont-Joli, Québec, G5H 3Z4 CanadaInstitut des sciences de la mer, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec, G5L 3A1 Canada
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Chatila K, Demers S, Mostajir B, Chanut JP, Monfort P. An endogenous periodicity exhibited in the activity of a natural bacterioplankton community isolated in mesocosms. Can J Microbiol 1999. [DOI: 10.1139/w99-047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In July 1996, bacterial abundance and incorporation of [3H]thymidine (3H-TdR) were determined every 4 h during a mesocosm experiment initially designed to study the effects of different intensities of ultraviolet-B (UVB) radiation on the summer planktonic community of the lower St. Lawrence Estuary. Water was obtained from the quay of the Maurice Lamontagne Institute (Mont-joli, Qué.) and incubated in experimental mesocosms (1500 L total volume, n = 8) with continuous mixing provided by a pumping system. During 72 h, different UVB intensities showed no significant effects on the bacterial incorporation of3H-TdR. This indicates that in the presence of other trophic levels and with continuous mixing, bacterioplankton responses to UVB are substantially different from those reported in axenic bacterial cultures or even whole-water incubations exposed to UVB at fixed depths. In conjunction with this observation,3H-TdR incorporation exhibited a significant periodic variation within all experimental treatments. The periodicity consisted of a 16-h cycle occurring independently of the time of the day. When the3H-TdR incorporation was normalized to cell abundance, the resulting cell-specific thymidine incorporation exhibited the same periodic oscillatory pattern. On the other hand, other factors suspected of inducing such a variability showed no consistent oscillation. In addition to suggesting an endogenously controlled activity of the studied bacterial community, the results of the present study indicate that failure of taking temporal variations of bacterial activity into account may introduce an error of almost 50% in the estimation of the daily thymidine incorporation rates. This represents a considerable error, because several studies rely on this measurement to estimate bacterial carbon production and to establish carbon budgets within different oceanic provinces.Key words: bacterioplankton, [3H]thymidine, ultraviolet-B radiation, periodicity, endogenous cycles, St. Lawrence Estuary.
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Mostajir B, Fagerbakke KM, Heldal M, Thingstad TF, Rassoulzadegan F. Elemental composition of individual pico- and nano-sized marine detrital particles in the northwestern Mediterranean Sea. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0399-1784(98)80041-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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