| 1. |
- Logares, Ramiro, et al.
(författare)
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Biogeography of bacterial communities exposed to progressive long-term environmental change
- 2013
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Ingår i: The ISME Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370. ; 7:5, s. 937-948
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Tidskriftsartikel (refereegranskat)abstract
- The response of microbial communities to long-term environmental change is poorly understood. Here, we study bacterioplankton communities in a unique system of coastal Antarctic lakes that were exposed to progressive long-term environmental change, using 454 pyrosequencing of the 16S rDNA gene (V3-V4 regions). At the time of formation, most of the studied lakes harbored marine-coastal microbial communities, as they were connected to the sea. During the past 20 000 years, most lakes isolated from the sea, and subsequently they experienced a gradual, but strong, salinity change that eventually developed into a gradient ranging from freshwater (salinity 0) to hypersaline (salinity 100). Our results indicated that present bacterioplankton community composition was strongly correlated with salinity and weakly correlated with geographical distance between lakes. A few abundant taxa were shared between some lakes and coastal marine communities. Nevertheless, lakes contained a large number of taxa that were not detected in the adjacent sea. Abundant and rare taxa within saline communities presented similar biogeography, suggesting that these groups have comparable environmental sensitivity. Habitat specialists and generalists were detected among abundant and rare taxa, with specialists being relatively more abundant at the extremes of the salinity gradient. Altogether, progressive long-term salinity change appears to have promoted the diversification of bacterioplankton communities by modifying the composition of ancestral communities and by allowing the establishment of new taxa. The ISME Journal (2013) 7, 937-948; doi:10.1038/ismej.2012.168; published online 20 December 2012
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| 2. |
- Logares, Ramiro, et al.
(författare)
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Infrequent marine-freshwater transitions in the microbial world
- 2009
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Ingår i: Trends in Microbiology. - : Elsevier BV. - 0966-842X .- 1878-4380. ; 17:9, s. 414-422
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Forskningsöversikt (refereegranskat)abstract
- Until recently, the evolutionary relationships between marine and freshwater microbes were unclear, but the use of molecular phylogenies is beginning to shed light on this subject. An increasing amount of studies are showing that marine and freshwater microbes (including viruses) are usually not closely related, often grouping into distinct marine and freshwater phylogenetic clusters, similar to what has been reported before for macroorganisms. These studies indicate that marine–freshwater transitions have been infrequent events during the diversification of microbes and that most of these transitions occurred a long time ago in evolutionary terms. Here we discuss the significance of recent studies addressing this question and consider possible avenues for future research.
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| 3. |
- Scharnweber, Kristin, 1983-, et al.
(författare)
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Comprehensive analysis of chemical and biological problems associated with browning agents used in aquatic studies
- 2021
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Ingår i: Limnology and Oceanography. - : Wiley. - 1541-5856. ; 19:12, s. 818-835
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Tidskriftsartikel (refereegranskat)abstract
- Inland waters receive and process large amounts of colored organic matter from the terrestrial surroundings. These inputs dramatically affect the chemical, physical, and biological properties of water bodies, as well as their roles as global carbon sinks and sources. However, manipulative studies, especially at ecosystem scale, require large amounts of dissolved organic matter with optical and chemical properties resembling indigenous organic matter. Here, we compared the impacts of two leonardite products (HuminFeed and SuperHume) and a freshly derived reverse osmosis concentrate of organic matter in a set of comprehensive mesocosm- and laboratory-scale experiments and analyses. The chemical properties of the reverse osmosis concentrate and the leonardite products were very different, with leonardite products being low and the reverse osmosis concentrate being high in carboxylic functional groups. Light had a strong impact on the properties of leonardite products, including loss of color and increased particle formation. HuminFeed presented a substantial impact on microbial communities under light conditions, where bacterial production was stimulated and community composition modified, while in dark potential inhibition of bacterial processes was detected. While none of the browning agents inhibited the growth of the tested phytoplankton Gonyostomum semen, HuminFeed had detrimental effects on zooplankton abundance and Daphnia reproduction. We conclude that the effects of browning agents extracted from leonardite, particularly HuminFeed, are in sharp contrast to those originating from terrestrially derived dissolved organic matter. Hence, they should be used with great caution in experimental studies on the consequences of terrestrial carbon for aquatic systems.
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