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A comparison of diatoms on horizontal and vertical substrates in Georgetown Lake, Montana
| Content Provider | Semantic Scholar |
|---|---|
| Author | Foris, William Joseph |
| Copyright Year | 1976 |
| Abstract | Georgetown Lake is a relatively small reservoir located in southwestern Montana. Its main uses are power production, industrial purposes, irrigation and recreation. The present study was part of a larger limnological project to evaluate the limnology of the reservoir. This particular study was undertaken to determine the seasonal periodicity and differences between the attached diatoms on horizontal and vertical plexiglass plates. Isotherms and conductivity isoclines showed that thermal and chemical stratification was non-existent during the ice free months. During ice cover there was a slight thermal stratification and a strong chemical stratification. Oxygen concentrations and pH values were found to be similar with the highest measurements occurring during the ice free months and the lowest values during the ice covered months. The water of Georgetown can be characterized as bicarbonate with calcium as its most abundant cation. Silica concentrations were found to be above the minimum requirement of most diatoms. A total of 31 genera, 159 species and 168 varieties of diatoms was identified. Pseudoperiphyton accounted for 26% of the average yearly percent cell volume on the horizontal plates and 11% on the vertical plates. Epithemia turgida, Fragilaria erotonensis and Rhopoladia gibba were the three most important species, respectively, according to average annual percent cell volume on both the horizontal and vertical substrates. In terms of average yearly percent relative abundance, pseudoperiphyton accounted for 29% on the horizontal plates and 15.4% on the vertical plates. The three most important taxa, according to average annual percent relative abundance, on both the horizontal and vertical substrates were, respectively, Aohnanthes Jninutissima, Fragilccria erotonensis and Stepthandiscus astrea. Estimates of seasonal production were based on organic weight accumulation numbers of diatoms, volume of diatoms and chlorophyll a measurements. The organic weight estimate of seasonal production illustrated a bimodal trend with an average accumulation rate of 47.83 mg.m^-2.day^-1 on the horizontal plates and 17.7 mg.m^-2.day^-1 on the vertical plates. Number and volume estimates both illustrated a unimodal trend. The average number of diatoms was 4548.cm-2.day-1 on horizontal plates and 1444.cm^-2.day^-1 on vertical plates. The average volume estimates was 4365 ú^3.cm^-2.day^-1 on horizontal plates and 1033 μ^3.cm^-2.day^-1 on vertical plates. Chlorophyll a production estimates illustrated a trimodal trend with an average accumulation rate of 16.83 μg.m^-2.day^-1 for the horizontal plates and 8.36 μg.m^-2. day^-1 for the vertical plates. The chlorophyll a to cell volume ratio versus cell volume curve suggests a density dependent relationship between chlorophyll a and cell volume. The chlorophyll a to organic weight ratio was used as an estimate of shading differences between horizontal and vertical substrates. At low organic weights vertical plates had a higher chlorophyll a to organic weight ratio than the horizontal plates. At moderate to high organic weights, vertical plates had a lower ratio than did the horizontal. Thus there is relatively more dead and non-active material on vertical plates than horizontal plates at moderate to high organic weights. |
| Starting Page | 1 |
| Ending Page | 120 |
| Page Count | 120 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://scholarworks.montana.edu/xmlui/bitstream/handle/1/5172/31762100137510.pdf;jsessionid=521F8A25E84EE152DE9F2D2ED52A54AE?sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
