Temporal and spatial relationships in the epipsammic diatom community

TitleTemporal and spatial relationships in the epipsammic diatom community
Publication TypeThesis
Year of Publication1983
AuthorsMiller AR
DegreeMaster of Science
Number of Pages87 pp.
UniversityBowling Green State University
CityBowling Green, OH

Transition from a flat, two-dimensional community to an erect, three-dimensional community has qualitatively been observed during diatom colonization on artificial substrates. To determine if the same progression occurs on natural substrates, epipsammic diatom communities were examined. Acid-cleaned sand grains were placed in a plexiglass collecting chamber and exposed to colonists in the west branch of the Maple River, Emmet County, Michigan between 29 June 82 and 1 August 82. Sand grains were collected with a coring device every 4 days beginning 4 July 82 and processed for light and scanning electron microscopy. Three-way analysis of independence revealed that epipsammic diatoms were significantly associated with cracks and valleys of sand grains. Chi-square analysis indicated that stalked diatoms, a minor component of the community, were randomly distributed on sand grains. Cluster analysis indicated that communities collected over the 33 day period were structurally very similar to each other (SIMI = 0.80). Two-way analysis of variance showed that the most common diatom habit was a flat, prostrate form while absolute abundances of diatoms on sand grains were significantly different on day 5 only. A non-significant interaction term indicated that diatom communities did not change from a flat, two-dimensional community to an erect three-dimensional community with time. Relative abundances were exceptionally low with the dominant species, Cocconeis diminuta, representing only 14% of the community. The epipsammon represent a specialized diatom community that seems well adapted for existence in a variable environment. Disturbance probably plays an important role in structuring the community and as a result community changes are only those of self-replacement or autosuccession.