Comparative studies on the biology and ecology of Ulva Fascita Delile and U.Pulchira Jaasund (Chlorophyta, Ulotrichales) at Oysterbay, Dar es Salaam.

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Date
1977
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University of Dar es Salaam
Abstract
The main objectives of the thesis were the following;- (i) To investigate the littoral distribution of Ulva fasciata and U. pulchr. (ii) To investigate the early stages of development in Ulva fasciata and U. pulchra (iii) To study the growth of the two species in relation to different salinity regimes. (iv) To study the response of Ulva fasciata and U.pulchra germlings to desiccation gradients. (v) To investigate the effect of temperature on the germlings of the two species. The study was conducted at Oyster Bay near the Police Officers’ Mess in Dar Es Salaam. This area was selected on the basis that several species of Ulva were found growing there and thus a suitable area for ecological studies on the species. Monthly samples of the thalli of Ulva fasciata and U. pulchra were collected along a line transect chosen randomly from within the study belt. Sample materials from individual sampling points were separately placed in labelled with-bags in field. In the laboratory each sample was sorted out into the respective species. The materials were then over dried overnight at 70oC in a Barlow-Whitney oven. Subsequently the dry weight for each species from each sampling point was measured. The dry weight data were then converted into standing crop data. The data thus obtained were than used in the plotting of graphs relating standing crop and distance from the cliff edge to the low water mark. Furthermore histograms relating standing crop and sampling months were plotted. The results were as follows: (i) It was shown that U. fasciata is more widespread in the area studied than U. pulchra. (ii) The germlings of both species showed similar patterns of early development. In all cases shoos developed faster than hold fasts. (iii) Both species were tolerant to the entire salinity range used (5-65%). (iv) Both species showed tolerance to all the desiccation periods tested (v) Ulva fasciata was shown to be tolerant to all the temperature levels tested for all the durations used. U. pulchra, in contrast was shown to be less tolerant to prolonged exposure to the highest temperature tested. The author concludes that these observations agree with what would be expected of the algae if they were to survive in this intertidal belt, where they frequently encounter diurnal as well as seasonal temperature fluctuations.
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Keywords
Algae, Oysterbay, See weeds, Chlorophyta, Ulotrichaceae, Ulvaceae
Citation
Shunula, J. P. T. (1977). Comparative studies on the biology and ecology of Ulva Fascita Delile and U.Pulchira Jaasund (Chlorophyta, Ulotrichales) at Oysterbay, Dar es Salaam. Master dissertation, University of Dar es Salaam. Available at (http://41.86.178.3/internetserver3.1.2/search.aspx?formtype=advanced)