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.

Carbon flux between an estuary and the ocean: a case for outwelling

Abstract: The classical outwelling hypothesis states that small coastal embayments (e.g. estuaries, wetlands) export their excess production to inshore marine waters. In line with this notion, the present study tested whether the Swartkops estuary acts as source or sink for carbon. To this end, concentrations of dissolved inorganic carbon (DIC), dissolved organic carbon (DOC) and particulate organic carbon (POC) were determined hourly during the first monthly spring and neap tides over one year in the tidal waters entering and leaving the estuary. Each sampling session spanned a full tidal cycle, yielding a total of 936 concentration estimates. Carbon fluxes were calculated by integrating concentrations with water flow rates derived from a hydrodynamic model calibrated for each sampling datum. Over the year, exports to marine waters markedly exceeded imports to the estuary for all carbon species: on the basis of total spring tidal drainage area, 1083 g m−2 of DIC, 103 g m−2 of DOC, and 123 g m−2 of POC left the estuary annually. Total carbon export from the estuary to the ocean amounted to 4755 tonnes, of which 83% was in the inorganic form (DIC). Thus, the bulk of carbon moving in the water column is inorganic - yet, DIC seems to be measured only rarely in most flux studies of this nature. Salt marshes cover extensive areas in this estuary and produce some carbon, particularly DOC, but productivity of the local Spartina species is low (P:B=1.1). Consequently, the bulk of carbon exported from the estuary appears to originate from the highly productive macroinvertebrate and the phytoplankton component and not from the salt marsh plants.

Mixing and circulation in the sundays river estuary, South Africa

Abstract: In the winter of 1987, a field exercise of 6 weeks' duration was carried out to investigate tidal dynamics and circulation patterns in the Sundays River estuary, on the south-east coast of South Africa. Measurements included continuous monitoring of water levels inside and outside the estuary, salinity and temperature profiles along the estuary at slack tides, current velocity profiles and near-bottom currents. The estuary was found to be in a highly stratified state at neap tides, but became completely mixed at spring tides. Dynamically, it can be divided into four longitudinal sections, each with an essentially different circulation pattern. Stratification and mixing in the water column appears to depend on: (a) semidiurnal tides in the local coastal ocean; (b) the spring-neap tidal cycle; (c) freshwater input. Direct effects of wind mixing were not observed. Frequent visual observations of the phenomenon of axial convergence are supported by water temperature and current velocity data.

The Appropriateness of Super's Career Theory among Black South Africans

Abstract: The appropriateness of Super's career theory among black South Africans is discussed in terms of developmental stages, the self-concept, career maturity, and career decision-making. Suggestions are provided as to how these constructs may need to be re-evaluated and thus become more meaningful to career counsellors and researchers.