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Regional estimates of potential new production in the southern Benguela upwelling system
The estimation of annual potential new production at a regional scale for the decade of the 1980s provides the main focus of this thesis. New production is the proportion of total primary production which relies on the uptake of NO₃-N by the phytoplankton while potential new production assumes that...
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| Format: | Thesis |
| Language: | English |
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Department of Oceanography
2016
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| _version_ | 1867613972057817088 |
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| access_status_str | Open Access |
| author | Waldron, Howard Neil |
| author2 | Brundrit, Geoff |
| author_browse | Brundrit, Geoff Waldron, Howard Neil |
| author_facet | Brundrit, Geoff Waldron, Howard Neil |
| author_sort | Waldron, Howard Neil |
| collection | Thesis |
| description | The estimation of annual potential new production at a regional scale for the decade of the 1980s provides the main focus of this thesis. New production is the proportion of total primary production which relies on the uptake of NO₃-N by the phytoplankton while potential new production assumes that all the NO₃-N available to primary producers is assimilated. The Redfield ratio between carbon and nitrogen in the marine environment was used to express rates of potential new production in terms of carbon. In order to arrive at annual estimates of potential new production it was necessary to progress from the event-scale to the annual scale. This was achieved by the adoption of two novel methods of approach. Event-scale estimates of potential new production were made by assessing the amount of NO₃-N present in the nominal euphotic zone as a result of upwelling. Remotely-sensed images of sea surface temperature (SST) coincident with or shortly after upwelling events were used in combination with a derived relationship between SST and NO₃-N concentrations integrated over the depth range of the productive surface layer in the southern Benguela region. In this way it was possible to overcome the main shortcoming of passive satellite imagery by quantifying a sub-surface variable. The event-scale estimates of potential new production were extrapolated to the annual-scale by taking into account the dynamics of the system. Sea level fluctuation at the coast preceding upwelling events was found to be related to the event-scale estimates of introduced NO₃-N and hence used as a proxy for upwelling. Using a ten year record of sea level, estimates of annual potential new production, spanning the period June to May inclusive, were made for the period 1980/81 to 1989/90. Bibliography: pages 92-108. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/18343 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:44:38.112Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2016 |
| publishDateRange | 2016 |
| publishDateSort | 2016 |
| publisher | Department of Oceanography |
| publisherStr | Department of Oceanography |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/18343 Regional estimates of potential new production in the southern Benguela upwelling system Waldron, Howard Neil Brundrit, Geoff Probyn, Trevor A Oceanography The estimation of annual potential new production at a regional scale for the decade of the 1980s provides the main focus of this thesis. New production is the proportion of total primary production which relies on the uptake of NO₃-N by the phytoplankton while potential new production assumes that all the NO₃-N available to primary producers is assimilated. The Redfield ratio between carbon and nitrogen in the marine environment was used to express rates of potential new production in terms of carbon. In order to arrive at annual estimates of potential new production it was necessary to progress from the event-scale to the annual scale. This was achieved by the adoption of two novel methods of approach. Event-scale estimates of potential new production were made by assessing the amount of NO₃-N present in the nominal euphotic zone as a result of upwelling. Remotely-sensed images of sea surface temperature (SST) coincident with or shortly after upwelling events were used in combination with a derived relationship between SST and NO₃-N concentrations integrated over the depth range of the productive surface layer in the southern Benguela region. In this way it was possible to overcome the main shortcoming of passive satellite imagery by quantifying a sub-surface variable. The event-scale estimates of potential new production were extrapolated to the annual-scale by taking into account the dynamics of the system. Sea level fluctuation at the coast preceding upwelling events was found to be related to the event-scale estimates of introduced NO₃-N and hence used as a proxy for upwelling. Using a ten year record of sea level, estimates of annual potential new production, spanning the period June to May inclusive, were made for the period 1980/81 to 1989/90. Bibliography: pages 92-108. 2016-03-28T14:44:42Z 2016-03-28T14:44:42Z 1996 Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/18343 eng application/pdf Department of Oceanography Faculty of Science University of Cape Town |
| spellingShingle | Oceanography Waldron, Howard Neil Regional estimates of potential new production in the southern Benguela upwelling system |
| thesis_degree_str | Doctoral |
| title | Regional estimates of potential new production in the southern Benguela upwelling system |
| title_full | Regional estimates of potential new production in the southern Benguela upwelling system |
| title_fullStr | Regional estimates of potential new production in the southern Benguela upwelling system |
| title_full_unstemmed | Regional estimates of potential new production in the southern Benguela upwelling system |
| title_short | Regional estimates of potential new production in the southern Benguela upwelling system |
| title_sort | regional estimates of potential new production in the southern benguela upwelling system |
| topic | Oceanography |
| url | http://hdl.handle.net/11427/18343 |
| work_keys_str_mv | AT waldronhowardneil regionalestimatesofpotentialnewproductioninthesouthernbenguelaupwellingsystem |