Insights into foraminiferal influences on microfabrics of microbialites at Highborne Cay, Bahamas

Joan M. Bernhard*, Virginia P. Edgcomb, Pieter T. Visscher, Anna McIntyre-Wressnig, Roger E. Summons, Mary L. Bouxsein, Leeann Louis, Marleen Jeglinski

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    36 Citations (Scopus)


    Microbialites, which are organosedimentary structures formed by microbial communities through binding and trapping and/or in situ precipitation, have a wide array of distinctive morphologies and long geologic record. The origin of morphological variability is hotly debated; elucidating the cause or causes of microfabric differences could provide insights into ecosystem functioning and biogeochemistry during much of Earth's history. Although rare today, morphologically distinct, co-occurring extant microbialites provide the opportunity to examine and compare microbial communities that may be responsible for establishing and modifying microbialite microfabrics. Highborne Cay, Bahamas, has extant laminated (i.e., stromatolites) and clotted (i.e., thrombolites) marine microbialites in close proximity, allowing focused questions about how community composition relates to physical attributes. Considerable knowledge exists about prokaryotic composition of microbialite mats (i.e., stromatolitic and thrombolitic mats), but little is known about their eukaryotic communities, especially regarding heterotrophic taxa. Thus, the heterotrophic eukaryotic communities of Highborne stromatolites and thrombolites were studied. Here, we show that diverse foraminiferal communities inhabit microbialite mat surfaces and subsurfaces; thecate foraminifera are relatively abundant in all microbialite types, especially thrombolitic mats; foraminifera stabilize grains in mats; and thecate reticulopod activities can impact stromatolitic mat lamination. Accordingly, and in light of foraminiferal impacts on modern microbialites, our results indicate that the microbialite fossil record may reflect the impact of the radiation of these protists.

    Original languageEnglish
    Pages (from-to)9830-9834
    Number of pages5
    JournalProceedings of the National Academy of Sciences of the United States of America
    Issue number24
    Publication statusPublished - 11 Jun 2013


    • Geobiology
    • Neoproterozoic
    • Ooid
    • Sedimentology


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