The microbial communities of the modern marine stromatolites at Highborne Cay, Bahamas [electronic resource] / by John F. Stolz [and others]
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Online Access |
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| Format: | Government Document Electronic eBook |
| Language: | English |
| Published: |
Washington, D.C. :
Smithsonian Institution, National Museum of Natural History,
[2009]
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| Series: | Atoll research bulletin ;
no. 567. |
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| Abstract: | An intensive multi-year field study of the modern marine stromatolites at Highborne Cay, Bahamas has identified a variety of microbial communities that colonize the stromatolite surfaces. They include both bacterial and diatom dominated communities. The "classic" microbial communities are those described by Reid et al. (2000). They include Schizothrix mats, dominated by S. gebeleinii, which trap and bind ooid sand grains (Type 1 mat); biofilm mats, composed of sulfate reducing bacteria, which form thin crusts of microcrystalline carbonate (Type 2 mat); and Solentia mats, dominated by coccoid endolithic Solentia species, which create cemented layers of fused sand grains (Type 3 mat). Another bacterial mat, termed "pudding mat" due to its pudding-like texture, is dominated by thin filaments of Phormidium sp. and single filaments of S. gebeleinii, but may also be colonized by a unique species of coccoid cyanobacterium related to Cyanothece. The diatom mats include stalked diatoms and tube diatoms. The stalked diatom mats form as a thin (1-3 mm) surface pink fuzz comprised of Striatella unipunctata, or a yellow fuzz that may develop into a thick (0.5-1 cm) yellow fur with Licmophora remulus and Licmophora paradoxa. The tube diatom mats, which occur as discrete pustules that may coalesce to create uniform blankets, are formed by naviculid--like tube diatoms. These different mat types recognized based on field descriptions and light microscopy also show distinct differences based on microbial fingerprinting and carbohydrate fractionation. Denaturing gradient gel electrophoresis (DGGE) analyses show similarities between stalked diatom mat types and "classic" mat types 1 and 2; these mats cluster separately from tube diatom mats and pudding mats, which each form distinct clades. In addition, the carbohydrate fractions of classic mat types are composed mostly of structural extracellular polymeric secretions (EPS), whereas stalked diatom and pudding mats contain predominantly non-structural carbohydrates. Although the pudding mats and diatom communities can contribute to the trapping of ooids, the stabilization of the unconsolidated sediment ultimately requires binding by S. gebeleinii. The combination of carbohydrate composition and ability to rapidly rebound after burial result in the high erosion resistance exhibited by the "classic" mats. Conversely, the extremely sensitive nature of diatoms to burial results in the low erosion resistance of the diatom mats. Nevertheless, all may contribute to the biogenesis of the Highborne Cay stromatolites. |
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| Item Description: | Title from title screen (Smithsonian Institution, viewed on Nov. 10, 2010) "July 2009." |
| Physical Description: | 1 online resource (29 pages) : illustrations (some color), maps (some color) |
| Bibliography: | Includes bibliographical references (pages 26-29) |