Biogeochemistry of Carbon Cycling in Hypersaline Mats: Linking the Present to the Past through Biosignatures

Visscher, Pieter T.; Dupraz, Christophe; Braissant, Olivier; Gallagher, Kimberley L.; Glunk, Christina; Casillas, Lilliam; Reed, Rachel E. S.

doi:10.1007/978-90-481-3799-2_23

Cited by 18 publications

(24 citation statements)

References 89 publications

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“…Complex mineralized microbial structures are commonly observed on a stable substrate [for example, Shark Bay (Jahnert & Collins, ), Storr's Lake (Mann & Nelson, ; Dupraz et al ., ) and Highborne Cay (Reid et al ., , )]. Mats developing on a soft substrate are poorly mineralized [for example, this study; Salt Pan (Dupraz et al ., ; Visscher et al ., )]. Therefore, a semi‐lithified to lithified substrate seems to favour the establishment of microbialites.…”

Section: Discussionmentioning

confidence: 97%

“…Microbial mats preferentially develop in environments protected from desiccation and exposure to UV radiation, such as in cryptic voids (Gelatinous and Rusty microbial biofilms) or in the deeper parts of the lagoon (Unconsolidated microbial mats) where UV radiation is quenched by the depth and turbidity of the water column (Visscher et al ., ). In these non‐mineralized mats, the degradation of EPS is slow and incomplete, resulting in non‐mineralized microbial biofilms and mats.…”

Section: Discussionmentioning

confidence: 99%

“…Development of microbialites probably requires stable conditions. In Shark Bay, the water is clear, promoting high microbial activity (Pagès et al ., ) and possibly microbially induced/influenced mineralization (Visscher et al ., ). Most of the Storr's Lake stromatolites form at a water depth less than 40 cm, i.e.…”

Section: Discussionmentioning

confidence: 99%

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External controls on the distribution, fabrics and mineralization of modern microbial mats in a coastal hypersaline lagoon, Cayo Coco (Cuba)

et al. 2016

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Active, carbonate-mineralizing microbial mats flourish in a tropical, highly evaporative, marine-fed lagoonal network to the south of Cayo Coco Island (Cuba). Hypersaline conditions support the development of a complex sedimentary microbial ecosystem with diverse morphologies, a variable intensity of mineralization and a potential for preservation. In this study, the role of intrinsic (i.e. microbial) and extrinsic (i.e. physicochemical) controls on microbial mat development, mineralization and preservation was investigated. The network consists of lagoons, forming in the interdune depressions of a Pleistocene aeolian substratum; they developed due to a progressive increase in sea-level since the Holocene. The hydrological budget in the Cayo Coco lagoonal network changes from west to east, increasing the salinity. This change progressively excludes grazers and increases the saturation index of carbonate minerals, favouring the development and mineralization of microbial mats in the easternmost lagoons. Detailed mapping of the easternmost lagoon shows four zones with different flooding regimes. The microbial activity in the mats was recorded using light-dark shifts in conjunction with microelectrode O 2 and HS À profiles. High rates of O 2 production and consumption, in addition to substantial amounts of exopolymeric substances, are indicative of a potentially strong intrinsic control on mineralization. Seasonal, climate-driven water fluctuations are key for mat development, mineralization, morphology and distribution. Microbial mats show no mineralization in the permanently submersed zone, and moderate mineralization in zones with alternating immersion and exposure. It is suggested that mineralization is also driven by water-level fluctuations and evaporation. Mineralized mats are laminated and consist of alternating trapping and binding of grains and microbially induced magnesium calcite and dolomite precipitation. The macrofabrics of the mats evolve from early colonizing Flat mats to complex Cerebroid or Terrace structures. The 972 macrofabrics are influenced by the hydrodynamic regime: wind-driven waves inducing relief terraces in windward areas and flat morphologies on the leeward side of the lagoon. Other external drivers include: (i) storm events that either promote (for example, by bioclasts covering) or prevent (for example, by causing erosion) microbial mat preservation; and (ii) subsurface degassing, through mangrove roots and desiccation cracks covered by Flat mats (i.e. forming Hemispheroids and Cerebroidal structures). These findings provide in-depth insights into understanding fossil microbialite morphologies that formed in lagoonal settings.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

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External controls on the distribution, fabrics and mineralization of modern microbial mats in a coastal hypersaline lagoon, Cayo Coco (Cuba)

et al. 2016

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“…The degradation of EPS is believed to contribute in the mineralization of CaCO 3 (Reid et al, 2000; Dupraz and Visscher, 2005; Ercole, 2007), a very important process in global biogeochemical cycles, and the formation of stromatolites and other microbialites, which represent the oldest evidence of life on Earth (Awramik, 1984; Allwood et al, 2009). However, no organism capable of degrading EPS has been isolated from a microbial mat, although several studies have shown that EPS are readily utilized by the heterotrophic community of a variety of microbial mats, including those in Puerto Rico (Visscher et al, 1998, 1999, 2002, 2010; Decho et al, 2005; Braissant et al, 2009). Also, no other studies have looked at the degradation of EPS using microbial mats slurries and different antibiotic agents as the one presented here.…”

Section: Discussionmentioning

confidence: 99%

Microbial mats: an ecological niche for fungi

Cantrell

Duval-Pérez

2013

Front. Microbiol.

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Fungi were documented in tropical hypersaline microbial mats and their role in the degradation of complex carbohydrates (exopolymeric substance – EPS) was explored. Fungal diversity is higher during the wet season with Acremonium, Aspergillus, Cladosporium, and Penicillium among the more common genera. Diversity is also higher in the oxic layer and in young and transient mats. Enrichments with xanthan (a model EPS) show that without antibiotics (full community) degradation is faster than enrichments with antibacterial (fungal community) and antifungal (bacterial community) agents, suggesting that degradation is performed by a consortium of organisms (bacteria and fungi). The combined evidence from all experiments indicates that bacteria carried out approximately two-third of the xanthan degradation. The pattern of degradation is similar between seasons and layers but degradation is faster in enrichments from the wet season. The research suggests that fungi thrive in these hypersaline consortia and may participate in the carbon cycle through the degradation of complex carbohydrates.

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“…Of the many taxa to be impacted by the increase in salinity the Alphaproteobacteria showed a change in relative abundance of key taxa including an enrichment of Rhodospirillales (Figure 3), a group of purple-sulfur phototrophs that has been shown to be enriched in many hypersaline habitats [79,80]. Salinity has also been previously shown to significantly impact the metabolic activity of hypersaline mats under gradients and flux conditions [23,77,81]. Specifically, hypersalinity impedes rates of photosynthesis and nitrogen fixation and limits microbial uptake of dissolved organic carbon [23,82,83].…”

Section: Impact Of Salinity On Microbialite Diversitymentioning

confidence: 93%

Effects of Elevated Carbon Dioxide and Salinity on the Microbial Diversity in Lithifying Microbial Mats

et al. 2014

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Atmospheric levels of carbon dioxide (CO 2 ) are rising at an accelerated rate resulting in changes in the pH and carbonate chemistry of the world's oceans. However, there is uncertainty regarding the impact these changing environmental conditions have on carbonate-depositing microbial communities. Here, we examine the effects of elevated CO 2 , three times that of current atmospheric levels, on the microbial diversity associated with lithifying microbial mats. Lithifying microbial mats are complex ecosystems that facilitate the trapping and binding of sediments, and/or the precipitation of calcium carbonate into organosedimentary structures known as microbialites. To examine the impact of rising CO 2 and resulting shifts in pH on lithifying microbial mats, we constructed growth chambers that could continually manipulate and monitor the mat environment. The microbial diversity of the various treatments was compared using 16S rRNA gene pyrosequencing. The results indicated that elevated CO 2 levels during the six month exposure did not profoundly alter the microbial diversity, community structure, or carbonate precipitation in the microbial mats; however some key taxa, such as the sulfate-reducing bacteria Deltasulfobacterales, were enriched. These results suggest that some carbonate depositing ecosystems, such as the microbialites, may be more resilient to anthropogenic-induced environmental change than previously thought. OPEN ACCESSMinerals 2014, 4 146

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Biogeochemistry of Carbon Cycling in Hypersaline Mats: Linking the Present to the Past through Biosignatures

Cited by 18 publications

References 89 publications

External controls on the distribution, fabrics and mineralization of modern microbial mats in a coastal hypersaline lagoon, Cayo Coco (Cuba)

External controls on the distribution, fabrics and mineralization of modern microbial mats in a coastal hypersaline lagoon, Cayo Coco (Cuba)

Microbial mats: an ecological niche for fungi

Effects of Elevated Carbon Dioxide and Salinity on the Microbial Diversity in Lithifying Microbial Mats

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