Kopara in Polynesian atolls: early stages of formation of calcareous stromatolites

Défarge, Christian; Trichet, Jean; Maurin, A.; Hucher, Monique

doi:10.1016/0037-0738(94)90080-9

Cited by 70 publications

(50 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3) and R63 exhibited consistently low salinity correlated with their isolated position within the land rim of the atoll (Table 1). De´farge et al (1994b) noticed a raindependent decrease of salinity in pond R2 from 8.9 ø in 1983 to 1.0 ø in 1992. We measured a salinity of 7.8 ø in November 2001.…”

Section: Resultsmentioning

confidence: 99%

Cyanobacterial populations that build ‘kopara’ microbial mats in Rangiroa, Tuamotu Archipelago, French Polynesia

Richert¹,

Golubić²,

Guédès³

et al. 2006

European Journal of Phycology

View full text Add to dashboard Cite

Cyanobacterial populations, the primary producers and builders of 'kopara' microbial mats were studied in four selected ponds along the rim of the Rangiroa Atoll, French Polynesia using a polyphasic approach. Seven isolates were maintained in uni-cyanobacterial cultures, characterized morphotypically and phylogenetically by evaluating sequences of the 16S rRNA gene of about 620 base pairs in length. Cyanobacteria in natural populations were analyzed microscopically, characterized morphotypically, and compared with cultured strains. Three of the isolates were identified in the field samples: Lyngbya aestuarii, Johannesbaptistia pellucida and Chroococcus submarinus were present in the mats only as minor components, whereas the species of Schizothrix that dominated the mat community could not be cultured. The sequence of Johannesbaptistia pellucida is published for the first time. The phylogenetic and taxonomic relations are discussed on the basis of a reconstructed phylogenetic tree in relation to morphotypic characters. Sequences of Kopara isolates plot separately from those cultured from the lagoon of the neighbouring atoll Tikehau, indicating a narrow niche differentiation of benthic cyanobacterial taxa. The results support the application of a polyphasic approach to characterization, ecology and diversity of cyanobacteria.

show abstract

Section: Resultsmentioning

confidence: 99%

Cyanobacterial populations that build ‘kopara’ microbial mats in Rangiroa, Tuamotu Archipelago, French Polynesia

Richert¹,

Golubić²,

Guédès³

et al. 2006

European Journal of Phycology

View full text Add to dashboard Cite

show abstract

“…A variety of organic acids may be released by degradation of cyanobacteria or polymeric materials in EPS (e.g., Anderson et al 1987). Additionally, HMC splay cements of much smaller size were shown to nucleate directly on EPS associated with benthic cyanobacterial bioWlms by Défarge et al (1994). Hence, such cements may be indicative of processes within microbial bioWlms.…”

Section: High-mg Calcite (Hmc) Cementmentioning

confidence: 95%

Earliest diagenesis in scleractinian coral skeletons: implications for palaeoclimate-sensitive geochemical archives

Nothdurft

Webb

2008

Facies

View full text Add to dashboard Cite

Live-collected samples of four common reefbuilding coral genera (Acropora, Pocillopora, Goniastrea, Porites) from subtidal and intertidal settings of Heron Reef, Great Barrier Reef, show extensive early marine diagenesis where parts of the coralla less than 3 years old contain abundant macro-and microborings and aragonite, high-Mg calcite, low-Mg calcite, and brucite cements. Many types of cement are associated directly with microendoliths and endobionts that inhabit parts of the corallum recently abandoned by coral polyps. The occurrence of cements that generally do not precipitate in normal shallow seawater (e.g., brucite, low-Mg calcite) highlights the importance of microenvironments in coral diagenesis. Cements precipitated in microenvironments may not reXect ambient seawater chemistry. Hence, geochemical sampling of these cements will contaminate trace-element and stable-isotope inventories used for palaeoclimate and dating analysis. Thus, great care must be taken in vetting samples for both bulk and microanalysis of geochemistry. Visual inspection using scanning electron microscopy may be required for vetting in many cases.

show abstract

“…These exopolysaccharides preserve the integrity of the mat, prevent dessication and maintain cell hydrophobicity [2,23]. They also are involved in the precipitation of carbonates [6,7]. Since 2001, this ecosystem has been screened for innovative biomolecules, including novel microbial exopolysaccharides secreted under laboratory conditions by both bacteria and cyanobacteria [20,21].…”

Section: Introductionmentioning

confidence: 99%

Investigations into the uptake of copper, iron and selenium by a highly sulphated bacterial exopolysaccharide isolated from microbial mats

Moppert¹,

Costaouëc

Raguénès

et al. 2009

J Ind Microbiol Biotechnol

View full text Add to dashboard Cite

A bacterium isolated from microbial mats located on a polynesian atoll produced a high molecular weight (3,000 kDa) and highly sulphated exopolysaccharide. Previous studies showed that the chemical structure of this EPS consisted of neutral sugars, uronic acids, and high proportions of acetate and sulphate groups. The copper- and iron-binding ability of the purified pre-treated native EPS was investigated. Results showed that this EPS had a very high affinity for both copper (9.84 mmol g(-1) EPS) and ferrous iron (6.9 mmol g(-1) EPS). Amazingly, this EPS did not show any affinity for either ferric ions or selenium salts. This finding is one of the first steps in assessing the biotechnological potential of this polysaccharide.

show abstract

Kopara in Polynesian atolls: early stages of formation of calcareous stromatolites

Cited by 70 publications

References 8 publications

Cyanobacterial populations that build ‘kopara’ microbial mats in Rangiroa, Tuamotu Archipelago, French Polynesia

Cyanobacterial populations that build ‘kopara’ microbial mats in Rangiroa, Tuamotu Archipelago, French Polynesia

Earliest diagenesis in scleractinian coral skeletons: implications for palaeoclimate-sensitive geochemical archives

Investigations into the uptake of copper, iron and selenium by a highly sulphated bacterial exopolysaccharide isolated from microbial mats

Contact Info

Product

Resources

About