1. A Comparison of Diatom Processing Methods
Kyler J. Rogers1, Shelly C. Wu1, and Elizabeth A. Bergey1
1. Dept. of Biology and Oklahoma Biological Survey, 111 E. Chesapeake St. Norman, OK 73019
Introduction
Results
Diatoms are unicellular algae composed of glass cell walls.
The organic material in the sample needs to be removed in order to view the diatom cells for identification.
The hydrogen peroxide method is typically used to remove the organic material (Carr et al. 1986) and takes 24+ hours.
Muffle furnace processing removes the organic material in one hour or less (Zoto et al. 1973).
Objectives of this study:
1) Determine if processing diatoms with the muffle furnace will yield the same
results in diatom identification and community composition (as processing with
hydrogen peroxide).
2) Conduct a literature search on diatom processing methods that are used
in diatom research.
Cymbella sp. 1
Hydrogen Peroxide
Muffle Furnace
Cymbella sp. 2
Both methods cleaned the diatoms to reveal the details on their cell walls.
Live cell with organic material
Cleaned cell
Methods
One example of how the diatom community composition varies between methods
Hydrogen peroxide
Before After
Muffle Furnace
Processed 7 freshwater diatom samples (so far)
Hydrogen peroxide method:
Added 25 mL of Hydrogen Peroxide and boiled the sample for 1 hour.
2) Added 30 mL of Nitric Acid and boiled for 20 minutes.
3) Filled the beaker with distilled water and let it settle (24 hours).
4) Decanted ¾ of the sample and added distilled water (repeated this process 6 times).
Muffle furnace method:
1) Dried the sample on coverslips.
2) Placed the coverslips in a glass dish and placed it in the muffle furnace for 1 hour at 460oC.
Diatoms were identified with a microscope at 1000X magnification. At least 400 diatom valves were counted to determine the community composition.
The literature search was done by searching “diatom ecology” with a time range of We recorded what processing method and chemicals were used.
Species Richness
Muffle Furnace
Hydrogen peroxide
Sample 1 8
Sample 2 16 17
Sample 3
Poor quality sample
Sample 4 33 35
Sample 5 25 26
Sample 6 34
Sample 7 20 19
Summary of Results:
Species richness was similar between the two processing methods (muffle furnace and hydrogen peroxide).
The abundance of taxa in the communities varied between methods.
In the future, we need to process more samples to determine why the relative abundance differs between methods.
LITERATURE CITED
Zoto, G. Dillon, D. Schlichting, H. A Rapid Method for clearing taxonomic and ecological studies. Phycologia 12 (1/2), 1973.
Carr, J. Hergenrader, G. Troelstrup, N. A Simple, Inexpensive Method for Cleaning Diatoms. Transactions of the American Microscopical Society Vol. 105 (2), 1986.