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Emilio O Casamayor - One of the best experts on this subject based on the ideXlab platform.
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bacterial and archaeal community structure in the surface microlayer of high mountain lakes examined under two atmospheric aerosol loading scenarios
FEMS Microbiology Ecology, 2013Co-Authors: Maria Vilacosta, Albert Barberan, Jeanchristophe Auguet, Shalabh Sharma, Mary Ann Moran, Emilio O CasamayorAbstract:Bacteria and Archaea of the air–water surface microlayer (Neuston) and plankton from three high mountain lakes (Limnological Observatory of the Pyrenees, Spain) were analysed by 16S rRNA gene 454 pyrosequencing (V6 region) in two dates with different atmospheric aerosol loading conditions: (1) under a Saharan dust plume driven by southern winds; and (2) under northern winds with oceanic influence. In general, bacterial communities were richer than archaea, with estimated total richness of c. 2500 OTUs for Bacteria and c. 900 OTUs for Archaea equivalent to a sequencing effort of c. 250 000 and c. 20 000 sequences, respectively. The dominant bacterial OTU was affiliated to Actinobacteria. Archaea were one to two orders of magnitude less abundant than bacteria but were more evenly distributed. Apparently, Bacteroidetes and Thaumarchaeota sequences were preferentially found at the Neuston, but no consistent pattern in either total microbial abundance or richness was found in any sample. However, we observed more marked changes in microbial relative abundances between Neuston and plankton in the dust-influenced scenario. Higher community dissimilarities between Neuston and plankton were also found during the Saharan dust episode, and such differences were higher for Bacteria than for Archaea. Nonetheless, relatively few (< 0.05%) of the Neuston sequences matched previously identified airborne microorganisms, and none became important in the dates analysed.
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Bacterial and archaeal community structure in the surface microlayer of high mountain lakes examined under two atmospheric aerosol loading scenarios
FEMS microbiology ecology, 2013Co-Authors: Maria Vila-costa, Albert Barberan, Jeanchristophe Auguet, Shalabh Sharma, Mary Ann Moran, Emilio O CasamayorAbstract:Bacteria and Archaea of the air–water surface microlayer (Neuston) and plankton from three high mountain lakes (Limnological Observatory of the Pyrenees, Spain) were analysed by 16S rRNA gene 454 pyrosequencing (V6 region) in two dates with different atmospheric aerosol loading conditions: (1) under a Saharan dust plume driven by southern winds; and (2) under northern winds with oceanic influence. In general, bacterial communities were richer than archaea, with estimated total richness of c. 2500 OTUs for Bacteria and c. 900 OTUs for Archaea equivalent to a sequencing effort of c. 250 000 and c. 20 000 sequences, respectively. The dominant bacterial OTU was affiliated to Actinobacteria. Archaea were one to two orders of magnitude less abundant than bacteria but were more evenly distributed. Apparently, Bacteroidetes and Thaumarchaeota sequences were preferentially found at the Neuston, but no consistent pattern in either total microbial abundance or richness was found in any sample. However, we observed more marked changes in microbial relative abundances between Neuston and plankton in the dust-influenced scenario. Higher community dissimilarities between Neuston and plankton were also found during the Saharan dust episode, and such differences were higher for Bacteria than for Archaea. Nonetheless, relatively few (
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High similarity between bacterioNeuston and airborne bacterial community compositions in a high mountain lake area
FEMS microbiology ecology, 2008Co-Authors: Anna Hervas, Emilio O CasamayorAbstract:The bacterioNeuston (bacteria inhabiting the air–water interface) is poorly characterized and possibly forms a unique community in the aquatic environment. In high mountain lakes, the surface film is subjected to extreme conditions of life, suggesting the development of a specific and adapted bacterioNeuston community. We have studied the surface film of a remote high mountain lake in the Pyrenees by cloning the PCR-amplified 16S rRNA gene and comparing with bacteria present in underlying waters (UW), and airborne bacteria from the dust deposited on the top of the snow pack. We did not detect unusual taxa in the Neuston but rather very common and widespread bacterial groups. Betaproteobacteria and Actinobacteria accounted for >75% of the community composition. Other minor groups were Gammaproteobacteria (between 8% and 12%), Alphaproteobacteria (between 1% and 5%), and Firmicutes (1%). However, we observed segregated populations in Neuston and UW for the different clades within each of the main phylogenetic groups. The soil bacterium Acinetobacter sp. was only detected in the snow–dust sample. Overall, higher similarities were found between bacterioNeuston and airborne bacteria than between the former and bacterioplankton. The surface film in high mountain lakes appears as a direct interceptor of airborne bacteria useful for monitoring long-range bacterial dispersion.
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a hotspot for cold crenarchaeota in the Neuston of high mountain lakes
Environmental Microbiology, 2008Co-Authors: Jeanchristophe Auguet, Emilio O CasamayorAbstract:Summary We have surveyed the first 1 m of 10 oligotrophic high mountain lakes in the Central Pyrenees (Spain) for both abundance and predominant phylotypes richness of the archaeaplankton assemblage, using CARD-FISH and 16S rRNA gene sequencing respectively. Archaea inhabiting the air-water surface microlayer (Neuston) ranged between 3% and 37% of total 4,6-diamidino-2-phenylindole (DAPI) counts and were mainly Crenarchaeota of a new freshwater cluster distantly related to the Marine Group 1.1a. Conversely, most of the Archaea from the underlying waters (the remaining first 1 m integrated) were mainly Euryarchaeota of three distantly related branches ranging between 0.4% and 27% of total DAPI counts. Therefore, a consistent qualitative and quantitative spatial segregation was observed for the two main archaeal phyla between Neuston and underlying waters at a regional scale. We also observed a consistent pattern along the lakes surveyed between lake area, lake depth and water residence time, and the archaeal enrichment in the Neuston: the larger the lake the higher the proportion of archaea in the Neuston as compared with abundances from the underlying waters (n = 10 lakes; R2 > 0.80; P < 0.001, in all three cases). This is the first report identifying a widespread non-thermophilic habitat where freshwater planktonic Crenarchaeota can be found naturally enriched. High mountain lakes offer great research opportunities to explore the ecology of one of the most enigmatic and far from being understood group of prokaryotes.
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A hotspot for cold crenarchaeota in the Neuston of high mountain lakes.
Environmental microbiology, 2008Co-Authors: Jeanchristophe Auguet, Emilio O CasamayorAbstract:Summary We have surveyed the first 1 m of 10 oligotrophic high mountain lakes in the Central Pyrenees (Spain) for both abundance and predominant phylotypes richness of the archaeaplankton assemblage, using CARD-FISH and 16S rRNA gene sequencing respectively. Archaea inhabiting the air-water surface microlayer (Neuston) ranged between 3% and 37% of total 4,6-diamidino-2-phenylindole (DAPI) counts and were mainly Crenarchaeota of a new freshwater cluster distantly related to the Marine Group 1.1a. Conversely, most of the Archaea from the underlying waters (the remaining first 1 m integrated) were mainly Euryarchaeota of three distantly related branches ranging between 0.4% and 27% of total DAPI counts. Therefore, a consistent qualitative and quantitative spatial segregation was observed for the two main archaeal phyla between Neuston and underlying waters at a regional scale. We also observed a consistent pattern along the lakes surveyed between lake area, lake depth and water residence time, and the archaeal enrichment in the Neuston: the larger the lake the higher the proportion of archaea in the Neuston as compared with abundances from the underlying waters (n = 10 lakes; R2 > 0.80; P
Guillermo Guerao - One of the best experts on this subject based on the ideXlab platform.
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Temporal Variability in the Vertical and Mesoscale Spatial Distribution of Crab Megalopae (Crustacea: Decapoda) in the Northwestern Mediterranean
Estuarine Coastal and Shelf Science, 1999Co-Authors: Pere Abelló, Guillermo GueraoAbstract:Abstract The vertical and mesoscale horizontal patterns of the distribution of crab megalopae were studied from samples taken during two consecutive cruises in the spring of 1992 off the Catalan coast (NW Mediterranean) and are analysed in relation to environmental data. The spring hydrography in the study area, which included the waters along the shelf and slope over a submarine canyon, is characterized by high hydrographic variability. The most abundant species was an undescribed portunid (coded as SP02), followed by Liocarcinus depurator and Carcinus aestuarii . Some species were mainly present in Neuston samples during night-time hours, such as Atelecyclus sp., Goneplax rhomboides, Ebalia sp. or the anomurans Pisidia longicornis and Porcellana platycheles ; other species were present in the Neuston throughout the day and night, with a slight tendency to increase their abundance during the night, such as L. depurator and C. aestuarii . The distribution of megalopae showed a high temporal variability and reflected the hydrographic structure at the surface. The variability in the geographical position of the shelf-slope hydrographic front clearly affected the distribution of the larvae. Most megalopae were associated with the inshore waters of lower salinity than open seawaters.
Helene Masclaux - One of the best experts on this subject based on the ideXlab platform.
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temporal changes in essential fatty acid availability in different food sources in the littoral macrophyte zone
Hydrobiologia, 2014Co-Authors: Helene Masclaux, Gilles Bourdier, Lionel Jouve, Emilie DuffaudAbstract:In littoral environments, different food resources are available for zooplankters. In addition to seston, species may feed on biofilms growing on sediments, plants (epiphyton), and at the air–water interface (Neuston). However, despite a growing interest in these different biofilms, little is known about their food quality for microcrustaceans. In a field study, we measured changes in the food quality over time in terms of the essential fatty acid (EFA) content of different potential food sources for littoral consumers. The food quality of seston, Neuston, and epiphyton growing on three different aquatic macrophytes were assessed. Our results showed that there is an important seasonal variability within each food source. However, in the system studied, epiphytic biofilms, especially those of Ludwigia and Callitriche offered the highest food quality, in terms of EFA content, throughout the year. As the highest EFA concentrations in each food source were found consecutively, high concentrations of these physiologically important compounds are maintained in the system throughout the year. Therefore, greater diversity of food resources could affect ecosystem productivity.
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How pollen organic matter enters freshwater food webs
Limnology and Oceanography, 2013Co-Authors: Helene Masclaux, Gilles Bourdier, Marie-elodie Perga, Maiko Kagami, Christian Desvilettes, Alexandre BecAbstract:Huge amounts of pollen can accumulate at the air-water interface during the floral bloom of wind-pollinated trees. We hypothesized that such pollen rains act as subsidy pulses, promoting the development of a Neustonic microbial food web and the transfer of pollen organic carbon to aquatic consumers. During a pine pollen rain event on an oxbow lake, microorganism concentrations were by far higher in the Neuston, where pollen grains accumulated, than in the seston. Zooplankton species were also unevenly distributed in the two compartments. Bulk isotope and isotopes of fatty acid analyses revealed trophic partitioning among these zooplankton species, with some of the taxa foraging specifically on Neuston, where they benefit from pollen-derived carbon. Microorganisms were identified as a key element in the trophic upgrading of pollen food quality and in the transfer of pollen carbon to metazoan consumers. Pollen rains may thus contribute, as an allochthonous food pulse, to aquatic production at specific seasons, but they may also act as a structuring factor in lake habitats.
Emilie Duffaud - One of the best experts on this subject based on the ideXlab platform.
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temporal changes in essential fatty acid availability in different food sources in the littoral macrophyte zone
Hydrobiologia, 2014Co-Authors: Helene Masclaux, Gilles Bourdier, Lionel Jouve, Emilie DuffaudAbstract:In littoral environments, different food resources are available for zooplankters. In addition to seston, species may feed on biofilms growing on sediments, plants (epiphyton), and at the air–water interface (Neuston). However, despite a growing interest in these different biofilms, little is known about their food quality for microcrustaceans. In a field study, we measured changes in the food quality over time in terms of the essential fatty acid (EFA) content of different potential food sources for littoral consumers. The food quality of seston, Neuston, and epiphyton growing on three different aquatic macrophytes were assessed. Our results showed that there is an important seasonal variability within each food source. However, in the system studied, epiphytic biofilms, especially those of Ludwigia and Callitriche offered the highest food quality, in terms of EFA content, throughout the year. As the highest EFA concentrations in each food source were found consecutively, high concentrations of these physiologically important compounds are maintained in the system throughout the year. Therefore, greater diversity of food resources could affect ecosystem productivity.
Genuario Belmonte - One of the best experts on this subject based on the ideXlab platform.
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Spatial variation in biodiversity patterns of Neuston in the Western Mediterranean and Southern Adriatic Seas
Journal of Sea Research, 2017Co-Authors: Anita Liparoto, Giorgio Mancinelli, Genuario BelmonteAbstract:Abstract Neuston - comprising a diverse assemblage of organisms living in the surface layer of the water column - plays a unique ecological role in marine life. Notwithstanding its importance, quantitative information on its spatial structure are still limited, in particular for the Mediterranean Sea. Here, the spatial structure of Neuston assemblage of the Western Mediterranean and the Southern Adriatic Seas was analysed, with particular emphasis on the biodiversity pattern in the two study areas. A total of 59 stations were sampled in an oceanographic cruise conducted in May–June 2013. Additional analyses were performed on data on 21 stations sampled in the Southern Adriatic in March 2015 in order to confirm the generality of the patterns observed in the 2013 cruise. Geostatistical analyses indicated that in 2013 in the Southern Adriatic the variation in taxonomic richness, abundance, and ecological diversity of the Neuston across stations was characterized by a significant spatial autocorrelation. Conversely, in the Western Mediterranean a negligible spatial structure was observed. In addition, the taxonomic richness and ecological diversity of the Neuston resulted significantly higher in Southern Adriatic than in the Western Mediterranean. Data collected in the 2015 cruise confirmed a high taxonomic richness and diversity for the Southern Adriatic; furthermore, a significant spatial autocorrelation was observed for both parameters. The present study represents an original insight into the structure of the Neuston community in the Mediterranean Sea, providing strong evidence of the spatial variability of its diversity patterns. The influence of local and large-scale processes is discussed, and the need of more extended investigations is emphasized.