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Long-term salinity trends in Zandvlei estuary and implications for dominant macroalgae
Zandvlei is a system that has been highly modified by the urban environment of Cape Town. Salinity is a major driver determining the physical environment of estuaries. The macroalgal community of estuaries forms an important part of the ecology of these systems as primary producers. The salinity of...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2017
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| _version_ | 1867613143742545920 |
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| access_status_str | Open Access |
| author | Muhl, Sara |
| author2 | Bolton, John J |
| author_browse | Bolton, John J Muhl, Sara |
| author_facet | Bolton, John J Muhl, Sara |
| author_sort | Muhl, Sara |
| collection | Thesis |
| description | Zandvlei is a system that has been highly modified by the urban environment of Cape Town. Salinity is a major driver determining the physical environment of estuaries. The macroalgal community of estuaries forms an important part of the ecology of these systems as primary producers. The salinity of this environment is an important parameter determining the composition, abundance and diversity of these communities. Patterns of salinity fluctuations in the long term (1978-2003) and annually are described in order to establish how communities may vary. Zandvlei is in a Mediterranean climate and salinity was found to vary seasonally and monthly with fluctuations in rainfall. Historical records of macroalgae identified in the estuary were summarized and no record of the Polysiphonia sp., now dominant in the estuary, was found. Dominant macroalgae in the estuary were identified and grown under a range of salinities (0, 1, 5, 10, 20, 29 ppt). Dominant macroalgae included Cladophora sp., Polysiphonia sp. and Enteromorpha prolifera. None of these algae survived at O ppt. In 1 ppt E. prolifera survived but growth was retarded, Polysiphonia sp. survived but did not grow and Cladophora sp. grew successfully at this salinity. All three species have different optimum ranges for growth with E. prolifera preferring higher salinities, Cladophora sp. grew similarly across the range from 1 to 29 ppt and Polysiphonia sp. grew most rapidly at 5 ppt. Depending on the salinity range in the estuary different macroalgae will be dominant. This makes the macroalgae community quite resilient to fluctuating salinities. There should therefore always be estuarine macroalgae present in the estuary provided salinity does not drop below 1 ppt for an extended period. If salinities did drop below 1 ppt there could be an increase in freshwater algae. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/25721 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:31:28.055Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2017 |
| publishDateRange | 2017 |
| publishDateSort | 2017 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/25721 Long-term salinity trends in Zandvlei estuary and implications for dominant macroalgae Muhl, Sara Bolton, John J Hoffmann, Timm Systematics and Biodiversity Sciences Plant Ecology Zandvlei is a system that has been highly modified by the urban environment of Cape Town. Salinity is a major driver determining the physical environment of estuaries. The macroalgal community of estuaries forms an important part of the ecology of these systems as primary producers. The salinity of this environment is an important parameter determining the composition, abundance and diversity of these communities. Patterns of salinity fluctuations in the long term (1978-2003) and annually are described in order to establish how communities may vary. Zandvlei is in a Mediterranean climate and salinity was found to vary seasonally and monthly with fluctuations in rainfall. Historical records of macroalgae identified in the estuary were summarized and no record of the Polysiphonia sp., now dominant in the estuary, was found. Dominant macroalgae in the estuary were identified and grown under a range of salinities (0, 1, 5, 10, 20, 29 ppt). Dominant macroalgae included Cladophora sp., Polysiphonia sp. and Enteromorpha prolifera. None of these algae survived at O ppt. In 1 ppt E. prolifera survived but growth was retarded, Polysiphonia sp. survived but did not grow and Cladophora sp. grew successfully at this salinity. All three species have different optimum ranges for growth with E. prolifera preferring higher salinities, Cladophora sp. grew similarly across the range from 1 to 29 ppt and Polysiphonia sp. grew most rapidly at 5 ppt. Depending on the salinity range in the estuary different macroalgae will be dominant. This makes the macroalgae community quite resilient to fluctuating salinities. There should therefore always be estuarine macroalgae present in the estuary provided salinity does not drop below 1 ppt for an extended period. If salinities did drop below 1 ppt there could be an increase in freshwater algae. 2017-10-23T06:28:29Z 2017-10-23T06:28:29Z 2003 2017-02-22T12:51:41Z Bachelor Thesis Honours BSc (Hons) http://hdl.handle.net/11427/25721 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Systematics and Biodiversity Sciences Plant Ecology Muhl, Sara Long-term salinity trends in Zandvlei estuary and implications for dominant macroalgae |
| thesis_degree_str | Bachelor's / Honours |
| title | Long-term salinity trends in Zandvlei estuary and implications for dominant macroalgae |
| title_full | Long-term salinity trends in Zandvlei estuary and implications for dominant macroalgae |
| title_fullStr | Long-term salinity trends in Zandvlei estuary and implications for dominant macroalgae |
| title_full_unstemmed | Long-term salinity trends in Zandvlei estuary and implications for dominant macroalgae |
| title_short | Long-term salinity trends in Zandvlei estuary and implications for dominant macroalgae |
| title_sort | long term salinity trends in zandvlei estuary and implications for dominant macroalgae |
| topic | Systematics and Biodiversity Sciences Plant Ecology |
| url | http://hdl.handle.net/11427/25721 |
| work_keys_str_mv | AT muhlsara longtermsalinitytrendsinzandvleiestuaryandimplicationsfordominantmacroalgae |