DIATOM COLONIZATION, COMMUNITY STRUCTURE, AND SUCCESSION ON ARTIFICIAL SUBSTRATES IN FRESH WATER

KYLE DEAN HOAGLAND, University of Nebraska - Lincoln

Abstract

Examination of the three-dimensional structure of periphyton communities through time indicated that their microsuccession is analogous to higher plant succession. The development of attached diatom communities in two reservoirs was studied using artificial substrates, and the morphology of dominant organisms, patterns of spatial heterogeneity, and community interactions were documented with scanning electron microscopy. Of 93 taxa found, Gomphonema parvulum, G. olivaceum, Navicula graciloides, Nitzschia palea, and N. dissipata were dominant, depending upon season and reservoir. Comparisons of community diversity (SIMI) between reservoirs within seasons ranged from 0.023-0.848 (x = 0.310), indicating that the reservoirs were quite different with respect to the diatoms present and their apportionments. Colonization was slow the first two weeks in spring and fall, and throughout winter, but rapid during summer. Shifts in numerical dominance between certain species occurred in fall, spring and summer. These inverse correlations of abundances and the functional dominance of overgrowth suggested that competition for substrate surface area occurred in the periphyton. The colonization sequence was often predictable-a presumably organic coating and a variety of bacteria, was followed by low profile diatoms, and finally by an upperstory of long-stalked and large-rosette diatoms and filamentous green algae. Periphyton microsuccession is similar to higher plant succession in the consistent change in vertical community structure from low to high physical stature, in the association of numerical dominance with large stature (via cell size or long mucilaginous stalks), and in the progressive slow-down in the rate of succession. Diatom mucilage also structured the community by binding particulates and entrapping other algae, and it served as the mechanism for substrate attachment and perhaps as the basis for diatom-bacterial associations. A short-term summer study employing frequent sampling intervals was performed to further elucidate the early events in diatom colonization. Analysis of variance of diatom diversity from three overlapping growth series indicated that 2-6 day old communities were not significantly different, regardless of the day when they were collected, whereas older communities were different. Comparisons of community composition, including the diatoms present and their apportionments, generally showed that samples collected on the same date were slightly more similar than those of identical age. These results may be explained by measurements of periphyton biomass and standing crop (cell density, ash-free dry weight, and percent transmittance (%T) of the growth layer), which demonstrated that the early stages of colonization on artificial substrates were significantly affected by wave action, with the degree of influence directly proportional to the age of the community. Diatom diversity, however, increased throughout the two week period in series 1, regardless of turbulence. When combined with previous results (Section I), these data suggest that during the summer the first two weeks represent a colonization phase, followed by a period of rapid colonization, growth, and competitive displacement, when diversity decreases. Quantum irradiance and %T measurements during the first two weeks indicated that light was not limiting to growth at the substrate level beneath the periphyton layers; however, competition for light may occur in later succession.

Subject Area

Botany|Energy

Recommended Citation

HOAGLAND, KYLE DEAN, "DIATOM COLONIZATION, COMMUNITY STRUCTURE, AND SUCCESSION ON ARTIFICIAL SUBSTRATES IN FRESH WATER" (1981). ETD collection for University of Nebraska-Lincoln. AAI8113283.
https://digitalcommons.unl.edu/dissertations/AAI8113283

COinS