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.

‘To define the indefinable’: population classification and the census in South Africa

Abstract: The population of many countries, including South Africa, has been classified into discrete groups from colonial times until the present day, for purposes of census enumeration. A reading of the census results requires an understanding of the subtleties and shifts of the classification system, which were frequently related to a definition of legal and political rights, including place of residence. The national census has tended to reinforce the groups it was initially meant only to observe.

Origin and trophic importance of detritus-evidence from stable isotopes in the benthos of a small, temperate estuary.

Abstract: Ratios of 13C/12C and 15N/14N were measured in dissolved inorganic carbon (DIC), marginal vegetation, benthic macrodetritus (diameter > 1 mm) and selected invertebrate consumers in the Gamtoos estuary, South Africa to: (1) trace the provenance of benthic detrital deposits, and (2) determine the extent to which three abundant species of macroinvertebrates utilise this resource. DIC was strongly depleted in 13C with average δ13C values (−9.5±0.5‰) being typical of limnetic waters. Benthic detrital particles (δ13C−24.1±0.3‰) originated mainly from marginal vegetation (δ13C−25.7±0.3‰), but their slightly elevated carbon ratio suggests additional input from 13C-rich sources-possibly C4 plants cultivated on the floodplain. Populations of the fossorial ghost shrimp Callianassa kraussi, the bentho-pelagic amphipod Grandidierella lignorum and the epifaunal crab Hymenosoma robiculare together account for 96% of total benthic biomass in the upper regions of this estuary. Marked differences in trophic niches were evident among these three consumer species. Ghost shrimp (δ13C −32.5±0.3‰) foraged by filter-feeding on fine suspended particulate organic matter (δ13C−31.2±0.5‰). Amphipods (δ13C−28.0±0.6‰) utilised some benthic detritus but fed mainly on suspended material. Only the relatively rare crabs (δ13C−23.8±1.5‰) appeared to utilise benthic detrital particles to any significant extent. In the benthic consumer community of the upper Gamtoos estuary, suspension feeders make up 98% of biomass and thus clearly dominate over deposit feeders. This can be traced to the low contribution of higher plants (c. 13%) to overall carbon production, and detritus originating from macrophytes is consequently relatively unimportant in supporting invertebrate secondary production in this particular system.

The coastal ocean off the east coast of south africa

Abstract: SUMMARY The east coast of South Africa has a generally well-defined and narrow continental shelf area. This, combined with the poleward-flowing Agulhas Current, serves to characterise the coastal ocean in the region as an identifiable entity. Most physical oceanographic investigations have taken place off Natal, but more recently some intensive measurements have also been made off East London. The results are reviewed in terms of temperature and current variability under the prime influence of wind and the Agulhas Current. Different coastal regimes are identified, but the inherent variability emerges as a major factor. The consequences are discussed in relation to phenomena such as the ‘sardine run’.

Feeding ecology of major carnivorous fish from four eastern Cape estuaries

Abstract: Stomach content analyses were performed on eight carnivorous fish from four eastem Cape estuaries. Dietary importance was assessed by using three unrelated methods and by combining them to determine the index of relative importance of each food item. It was attempted to relate the percentage of fish with food in the stomach and the feeding intensity to the abundance of the fish in a particular estuary. In general fish consumed more food in estuaries where they were more abundant. The few exceptions that occurred could indicate that a particular estuary was selected for purposes other than food availability ego Tachysurus feliceps in the Krom estuary for spawning grounds or because of inter- or intraspecific competition for food ego T. feliceps and Monodactylus falciformis in the Krom and Argyrosomus hololepidotus in the Gamtoos and Sundays estuaries. Similarity analyses showed resource partitioning. Predators such as A. hololepidotus, Elops machnata, Lichia amia and Platycephalus indicus preferred teleost fishes such as mullets and Gilchristella aestuarius, whereas the stomach content of Pomadasys commersonni, T. feliceps and M. falciforrnis were dominated by Crustacea, particularly Upogebia africana. Most estuarine predators showed a diverse prey selection, but the