Many of the larger estuaries along the South African coastline are highly degraded due to human impacts, highlighting the need to conserve pristine systems. There are approximately 100 micro-estuaries along our coastline which have not yet been identified or classified and hence their ecological functioning is unknown. The aim of this study was to identify and classify micro-estuaries along the Eastern Cape coast. Specific objectives of the study were to: 1) map the distribution of estuarine habitats in a selection of micro-estuaries and assess changes over time; 2) measure the physico-chemical characteristics of the micro-estuaries in the field; 3) investigate the distribution of vegetation, identify macrophyte species and habitat integrity and classify the micro-estuaries sampled using abiotic and botanical characteristics. A total of 30 systems were identified of which 10 were selected for sampling which took place seasonally (2015-2016). A relationship between open water surface area and short term rainfall was only evident in Cunge, Sandy Bottom and Ichabana. In the field it was observed that after heavy rainfall, open water surface area increased and mouth breaching occurred. Salinity was the only water column characteristic that showed differences; salinity increased in response to over wash events. Sand was dominant in all systems and there were no differences in sediment characteristics. A total of 8 macroalgal species, 16 estuarine macrophyte species, six freshwater species and 72 riparian plant species were found. Seed bank reserves were low in all systems despite them being vegetated. Only abiotic characteristics were used for classification using Principle Components Analysis since there were no botanical differences between systems. Micro-estuaries were larger (> 0.03 ha), had a higher salinity (oligohaline, mesohaline and polyhaline conditions) and a constant water body. Micro-outlets were smaller (< 0.03 ha), had a lower salinity (oligohaline conditions were most common) and showed periods of drying. Five micro-estuaries (Shelbertsstroom, Kwesani, Cunge, Mtwendwe and Mtendwe) and five micro-outlets (Stromatolite, Sandy Bottom, Ichabana, Palm Tree and Black Rock) were classified. This study has shown that the micro-estuaries along the Eastern Cape coast are pristine (i.e. intact riparian zone and catchment), untouched and highly dynamic systems (i.e. great variation in water surface area and mouth condition) highlighting their need for protection.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nmmu/vital:27007 |
| Date | January 2017 |
| Creators | Naidoo, Lyndle Sherae |
| Publisher | Nelson Mandela Metropolitan University, Faculty of Science |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Masters, MSc |
| Format | xiii, 151 leaves, pdf |
| Rights | Nelson Mandela Metropolitan University |
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