Temporal Changes in the Community Structure and Kotosynthetic Production of Phytoplankton in Lake Babogaya, Ethiopia
| dc.contributor.advisor | Kifle, Demeke (PhD) | |
| dc.contributor.author | Major, Lesbimebet | |
| dc.date.accessioned | 2018-07-17T09:02:01Z | |
| dc.date.accessioned | 2023-11-08T16:33:30Z | |
| dc.date.available | 2018-07-17T09:02:01Z | |
| dc.date.available | 2023-11-08T16:33:30Z | |
| dc.date.issued | 2006-07 | |
| dc.description.abstract | The temporal variations in the taxonomic composition, biomass and photosynthetic production of phytoplankton in Lake Bishoftu-Guda were investigated for a period of one year, from November, 2004 to October, 2005. Concurrently changes in some physico-chemical environmental variables were studied. Temporal variations in inorganic nutrients were observed with the maximum values cOinciding with a period of relatively high rainfall at both stations. Lake's transparency was always high (ZSD > 1m). Since the lake was transparent due to low phytoplankton biomass and suspended inorganic particles throughout the study period, the extinction of underwater light was low. The phytoplankton community of this nutrient-poor and deep lake was dominated by dinof/agllates during the dry and short rain periods before a shift in dominance to diatoms occurred during the long rainy period. Phytoplankton biomass of Lake Bishoftu-Guda was found to vary from 4 to 20 (mean=1O.8) mg Chi a m-3 at the central station and from 3.96 to 24.2 (mean=lO. 2) mg Chi a m-3 at the near-shore station. The depthprofiles of gross photosynthetic activity were of a typical pattern for phytoplankton with light-inhibition at the surface and with light-saturated rates generally occurring at a depth of 0.9 m of the water column on all sampling dates. The light-saturated rates of photosynthesis (Amax) ranged from 106 to 407 mg O2 (-33.1 to 127 mg C) m-3 h-I. A strong and positive correlation (r=0.76, p=O.OOO) was found between Amax and phytoplankton biomass. Biomass-specific rate of photosynthetic production at light-saturation (Pmax) ranged from 19 to 29 mg O2 (mg chi arl h-I and was inversely related to phytoplankton biomass. Hourly integral photosynthesis (LA, g d m-2 h-I ), which was obtained by the Grid Enumeration Analysis ranged from 0.112 to 0.66 g O2 (-0.03 to 0.21 g C) m-2 h-I. There was a positive but weak correlation (0.36), P=O.OOO) between phytoplankton biomass and hourly integral photosynthesis, while the correlation between LA and Amax was 0.83. Daily production rates per unit area (LlA g d m-2 efl), were estimated from hourly integrated rates and the calculated daily integral production values ranged from 1.01 to 5.98 g O2 (-0.32 to 1.87 g C) m-2 efl. The temporal variations in species composition, biomass and photosynthetic production of phytoplankton are discussed in relation to physicochemical factors. | en_US |
| dc.identifier.uri | http://etd.aau.edu.et/handle/123456789/9008 | |
| dc.language.iso | en | en_US |
| dc.publisher | Addis Ababa University | en_US |
| dc.subject | Biology | en_US |
| dc.title | Temporal Changes in the Community Structure and Kotosynthetic Production of Phytoplankton in Lake Babogaya, Ethiopia | en_US |
| dc.type | Thesis | en_US |