University of Port Elizabeth

About: University of Port Elizabeth is a based out in . It is known for research contribution in the topics: Population & Estuary. The organization has 1067 authors who have published 1538 publications receiving 38560 citations. The organization is also known as: UPE & Universiteit van Port Elizabeth.

Increasing population of cape gannets on bird island, algoa bay, and observations on breeding success

Abstract: Summary Randall, R. and Ross, G. J. B. 1979. Increasing population of Cape Gannets on Bird Island, Algoa Bay, and observations on breeding success. Ostrich 50:168-175. The South African Gannet Sula capensis on Bird Island has doubled in numbers between 1956 and 1974 and the process is continuing. The increase is similar to that of the two closely related species S. serrator and S. bassana. We estimated from the colony surface area and nest density that the number of birds with nests in 1974/5 was approximately 77 000. Making allowance for non-breeders, there were about 100 000 adults in 1974/5. Guano harvests from 1938–75 show considerable annual fluctuations with an overall downward trend. Poor agreement was found when relating guano harvests to population estimates, when the latter are gauged by colony surface area. We suggest that guano harvests are not good indicators of gannet population trends on Bird Island, primarily because of harvesting methods and environmental conditions. The number of chicks ...

Upper Ordovician chitinozoans from the Cedarberg Formation of South Africa. Preliminary note

Abstract: Chitinozoans bracket the geological age of the Soom Shale at the base of the Cedarberg Formation of South Africa as Lower Silurian to Upper Ordovician whereby the oldest age is the more probable.

16O2/18O2 analysis of oxygen exchange in Dunaliella tertiolecta. Evidence for the inhibition of mitochondrial respiration in the light

Abstract: A mass spectrometric 16O2/18O2-isotope technique was used to analyse the rates of gross O2 evolution, net O2 evolution and gross O2 uptake in relation to photon fluence rate by Dunaliella tertiolecta adapted to 0.5, 1.0, 1.5, 2.0 and 2.5 M NaCl at 25°C and pH 7.0.

Dietary shifts: do grazers become browsers in the Thicket Biome?

Abstract: The diet of buffalo ( Syncerus coffer ) and Burchell's zebra ( Equus burchelli ) was investigated in the Addo Elephant National Park to test the hypothesis that the shortage of grass associated with thicket vegetation results in grazers increasing the proportion of dicotyledonous plant species in their diet. Diet composition, estimated from faecal analysis, indicated that 19 and 21 plant species were identified in the faeces of zebra and buffalo, respectively. Buffalo proved to have a higher percentage dicotyledonous (28.1 vs. 8.5 ) and lower percentage monocotyledonous (71.9 vs. 91.5 ) species in their diet than zebra. The grass Eragrostis curvula was found to be the dominant food item for both buffalo (18 of diet) and zebra (39 of diet) during the period of study. The present study indicated that a great proportion of the buffalo diet does in fact consist of grass, thereby refuting the perception that the Addo buffalo are primarily browsers. Both buffalo and zebra are specialised grazers and unsuited to a diet of browse. The probability of dietary shift by these grazers in the grass limited thicket vegetation is therefore challenged.