Biogeochemical cycling and microbial diversity in the thrombolitic microbialites of Highborne Cay, Bahamas

Thrombolites are unlaminated carbonate build-ups that are formed via the metabolic activities of complex microbial mat communities. The thrombolitic mats of Highborne Cay, Bahamas develop in close proximity (1-2 m) to accreting laminated stromatolites, providing an ideal opportunity for biogeochemic...

Full description

Saved in:
Bibliographic Details
Published in:Geobiology 2010-09, Vol.8 (4), p.337-354
Main Authors: MYSHRALL, K.L, MOBBERLEY, J.M, GREEN, S.J, VISSCHER, P.T, HAVEMANN, S.A, REID, R.P, FOSTER, J.S
Format: Article
Language:English
Subjects:
Bacteria - classification
Bacteria - cytology
Bacteria - genetics
Bacteria - isolation & purification
Bahamas
Biodiversity
Carbon - metabolism
Cluster Analysis
Cyanobacteria
Dichothrix
DNA - chemistry
DNA - genetics
DNA, Ribosomal - chemistry
DNA, Ribosomal - genetics
Eukaryota - classification
Eukaryota - cytology
Eukaryota - genetics
Eukaryota - isolation & purification
Geologic Sediments - microbiology
Molecular Sequence Data
Oxygen - metabolism
Phylogeny
RNA, Ribosomal, 16S - genetics
RNA, Ribosomal, 18S - genetics
Sequence Analysis, DNA
Sequence Homology
Soil Microbiology
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Thrombolites are unlaminated carbonate build-ups that are formed via the metabolic activities of complex microbial mat communities. The thrombolitic mats of Highborne Cay, Bahamas develop in close proximity (1-2 m) to accreting laminated stromatolites, providing an ideal opportunity for biogeochemical and molecular comparisons of these two distinctive microbialite ecosystems. In this study, we provide the first comprehensive characterization of the biogeochemical activities and microbial diversity of the Highborne Cay thrombolitic mats. Morphological and molecular analyses reveal two dominant mat types associated with the thrombolite deposits, both of which are dominated by bacteria from the taxa Cyanobacteria and Alphaproteobacteria. Diel cycling of dissolved oxygen (DO) and dissolved inorganic carbon (DIC) were measured in all thrombolitic mat types. DO production varied between thrombolitic types and one morphotype, referred to in this study as 'button mats', produced the highest levels among all mat types, including the adjacent stromatolites. Characterization of thrombolite bacterial communities revealed a high bacterial diversity, roughly equivalent to that of the nearby stromatolites, and a low eukaryotic diversity. Extensive phylogenetic overlap between thrombolitic and stromatolitic microbial communities was observed, although thrombolite-specific cyanobacterial populations were detected. In particular, the button mats were dominated by a calcified, filamentous cyanobacterium identified via morphology and 16S rRNA gene sequencing as Dichothrix sp. The distinctive microbial communities and chemical cycling patterns within the thrombolitic mats provide novel insight into the biogeochemical processes related to the lithifying mats in this system, and provide data relevant to understanding microbially induced carbonate biomineralization.
ISSN:1472-4677
1472-4669
DOI:10.1111/j.1472-4669.2010.00245.x