T62 Insights from Microfossils, Palynology, and Their Modern Analogs: From Traditional to Emerging Techniques

Sunday, 4 November 2018
1:30 PM - 5:30 PM
Room 140

TAXONOMIC AND MINERALOGICAL ANALYSES OF AGGLUTINATED TESTATE AMOEBAE AND FORAMINIFERA AND THE APPLICATION OF TESTATE AMOEBAE IN ASSESSING THE SPREAD OF ATMOSPHERIC PARTICULATE MATTER

Paper number: T62-10
Program: Technical Sessions
Time: 3:45 PM – 4:00 PM

Authors

Abstract

Both agglutinated foraminifera and testate amoebae have been used extensively in ecological and paleoecological studies as bioindicators of water quality. While both groups of organisms are unicellular protozoa, foraminifera are found in marine environments and testate amoebae are found in terrestrial environments. Both produce mineralized shells, either by secretion or the agglutination of mineral grains called xenosomes. Many testate amoebae species are divided into subcategories called “strains” based on minor morphological differences, which are thought to reflect changes in different environmental parameters. In this study we are using an Environmental Scanning Electron Microscope coupled with an Energy Dispersive X-ray Spectrometer (ESEM-EDS) to analyze the mineralogical composition of the xenosomes in different morpho-species “strains” of testate amoebae. We focused on three common species, Centropyxis aculeata, Difflugia oblonga, and Mediolus corona. Both C. aculeata and D. oblonga have been divided into a number of morpho-species “strains.” The analyzed species have been taken from a variety of locations with different levels of environmental stress, including water bodies affected by urbanization, toxic chemical spills, and coal mining. It is not known if agglutinated testate amoebae can select specific mineral grains for use as xenosomes, whereas the phenomenon of grain selection by agglutinated foraminifera is well known. We will compare the mineralogical composition results for our testate amoebae specimens with ESEM-EDS analysis on the xenosomes of several species of agglutinated foraminifera from Florida. More research has been completed on the mechanisms of agglutination in foraminifera, but it is not known if the two groups of organisms utilize similar processes. The ESEM-EDS results from this study should help us further understand mechanisms of shell formation and clarify taxonomic confusion in the relevant species. This study will also address the possible application of testate amoebae in assessing the spread of atmospheric particulate matter as recent studies in Europe have shown the inclusion of deposited particulate matter in testate amoebae shells.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-323322

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