Vertical stratification and microbial assemblage of a microbial mat in the Ebro Delta (Spain)

Mir, Joan; Martínez-Alonso, Maira; Esteve, Isabel; Guerrero, Ricardo

doi:10.1111/j.1574-6968.1991.tb04795.x

Cited by 52 publications

(15 citation statements)

References 17 publications

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“…Our assumption that these mat sections were of different ages is based on (1) their qualitative differences (slight green banding vs. multicolored layering, loose vs. stabilized sediment) and (2) their close proximity (similar biotic and abiotic characteristics). These definitions are consistent with descriptions of coastal mat development elsewhere (Stal et al, 1985; Mir et al, 1991; Stal and Caumette, 1994). Henceforth, we refer to the two cores from 2010 as “young mat” (YM-10) and “old mat,” (OM-10).…”

Section: Methodssupporting

confidence: 88%

Millimeter-scale patterns of phylogenetic and trait diversity in a salt marsh microbial mat

et al. 2012

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Intertidal microbial mats are comprised of distinctly colored millimeter-thick layers whose communities organize in response to environmental gradients such as light availability, oxygen/sulfur concentrations, and redox potential. Here, slight changes in depth correspond to sharp niche boundaries. We explore the patterns of biodiversity along this depth gradient as it relates to functional groups of bacteria, as well as trait-encoding genes. We used molecular techniques to determine how the mat’s layers differed from one another with respect to taxonomic, phylogenetic, and trait diversity, and used these metrics to assess potential drivers of community assembly. We used a range of null models to compute the degree of phylogenetic and functional dispersion for each layer. The SSU-rRNA reads were dominated by Cyanobacteria and Chromatiales, but contained a high taxonomic diversity. The composition of each mat core was significantly different for developmental stage, year, and layer. Phylogenetic richness and evenness positively covaried with depth, and trait richness tended to decrease with depth. We found evidence for significant phylogenetic clustering for all bacteria below the surface layer, supporting the role of habitat filtering in the assembly of mat layers. However, this signal disappeared when the phylogenetic dispersion of particular functional groups, such as oxygenic phototrophs, was measured. Overall, trait diversity measured by orthologous genes was also lower than would be expected by chance, except for genes related to photosynthesis in the topmost layer. Additionally, we show how the choice of taxa pools, null models, spatial scale, and phylogenies can impact our ability to test hypotheses pertaining to community assembly. Our results demonstrate that given the appropriate physiochemical conditions, strong phylogenetic, and trait variation, as well as habitat filtering, can occur at the millimeter-scale.

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Section: Methodssupporting

confidence: 88%

Millimeter-scale patterns of phylogenetic and trait diversity in a salt marsh microbial mat

et al. 2012

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“…Photosynthetic microbial mats develop at the watersediment interface in shallow environments such as 0168 [1,2], sheltered sandy beaches [3,4], or hypersaline salterns [5,6]. Most of these microbial mats are formed of horizontally stratified, multicolored and cohesive thin layers of several functional groups of microorganisms, such as cyanobacteria, colorless sulfur bacteria, purple sulfur bacteria and sulfate-reducing bacteria, distributed along vertical microgradients of oxygen, sulfide and light [7,8].…”

Section: Introductionmentioning

confidence: 99%

Characterization of functional bacterial groups in a hypersaline microbial mat community (Salins-de-Giraud, Camargue, France)

Fourçans

Oteyza²,

Wieland

et al. 2004

FEMS Microbiology Ecology

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A photosynthetic microbial mat was investigated in a large pond of a Mediterranean saltern (Salins-de-Giraud, Camargue, France) having water salinity from 70 per thousand to 150 per thousand (w/v). Analysis of characteristic biomarkers (e.g., major microbial fatty acids, hydrocarbons, alcohols and alkenones) revealed that cyanobacteria were the major component of the pond, in addition to diatoms and other algae. Functional bacterial groups involved in the sulfur cycle could be correlated to these biomarkers, i.e. sulfate-reducing, sulfur-oxidizing and anoxygenic phototrophic bacteria. In the first 0.5 mm of the mat, a high rate of photosynthesis showed the activity of oxygenic phototrophs in the surface layer. Ten different cyanobacterial populations were detected with confocal laser scanning microscopy: six filamentous species, with Microcoleus chthonoplastes and Halomicronema excentricum as dominant (73% of total counts); and four unicellular types affiliated to Microcystis, Chroococcus, Gloeocapsa, and Synechocystis (27% of total counts). Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments confirmed the presence of Microcoleus, Oscillatoria, and Leptolyngbya strains (Halomicronema was not detected here) and revealed additional presence of Phormidium, Pleurocapsa and Calotrix types. Spectral scalar irradiance measurements did not reveal a particular zonation of cyanobacteria, purple or green bacteria in the first millimeter of the mat. Terminal-restriction fragment length polymorphism analysis of PCR-amplified 16S rRNA gene fragments of bacteria depicted the community composition and a fine-scale depth-distribution of at least five different populations of anoxygenic phototrophs and at least three types of sulfate-reducing bacteria along the microgradients of oxygen and light inside the microbial mat.

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“…Microbial mat communities on the sand flats of the Ebro Delta were analyzed for the first time by Mir et al [11] using classical microbiological methods. These mats are composed of several pigmented layers dominated by phototrophic organisms.…”

Section: Introductionmentioning

confidence: 99%

Diversity of anoxygenic phototrophic sulfur bacteria in the microbial mats of the Ebro Delta: a combined morphological and molecular approach

Martínez-Alonso

Bleijswijk

Gaju

et al. 2005

FEMS Microbiology Ecology

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The diversity of purple and green sulfur bacteria in the multilayered sediments of the Ebro Delta was investigated. Specific oligonucleotide primers for these groups were used for the selective amplification of 16S rRNA gene sequences. Subsequently, amplification products were separated by denaturing gradient gel electrophoresis and sequenced, which yielded a total of 32 sequences. Six of the sequences were related to different cultivated members of the green sulfur bacteria assemblage, whereas seven fell into the cluster of marine or halophilic Chromatiaceae. Six sequences were clustered with the family Ectothiorhodospiraceae, three of the six being closely related to chemotrophic bacteria grouped together with Halorhodospira genus, and the other three forming a group related to the genus Ectothiorhodospira. The last thirteen sequences constituted a cluster where no molecular isolate from microbial mats has so far been reported. Our results indicate that the natural diversity in the ecosystem studied has been significantly underestimated in the past and point out the presence of novel species not related to all known purple sulfur bacteria. Furthermore, the detection of green sulfur bacteria, after only an initial step of enrichment, suggests that -- with the appropriate methodology -- several genera, such as Prosthecochloris, could be established as regular members of marine microbial mats.

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Vertical stratification and microbial assemblage of a microbial mat in the Ebro Delta (Spain)

Cited by 52 publications

References 17 publications

Millimeter-scale patterns of phylogenetic and trait diversity in a salt marsh microbial mat

Millimeter-scale patterns of phylogenetic and trait diversity in a salt marsh microbial mat

Characterization of functional bacterial groups in a hypersaline microbial mat community (Salins-de-Giraud, Camargue, France)

Diversity of anoxygenic phototrophic sulfur bacteria in the microbial mats of the Ebro Delta: a combined morphological and molecular approach

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