Browsing by Author "Forbes, Cherie Janine"
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- ItemOpen AccessAnalysis of protein content of two kelps, Ecklonia maxima and Laminaria pallida for feed in abalone aquaculture(2009) Forbes, Cherie Janine; Bolton, John JKelp is widely used as feed in the abalone aquaculture industry in South Africa, and farmers have reported different feed quality between the two dominant kelp species occurring along the west and southwest coasts with Ecklonia maxima reported as having a better Food Conversion Ratio (FCR) than Laminaria pallida. Total protein content and other nutritional components (Carbon, Nitrogen and moisture content) of two kelp species, E. maxima and L. pallida were investigated. The kelps were collected from Kommetjie (borderline of west and southwest coasts). Seasonal total protein content of E.maxima from a commercially-harvested kelp bed in Jacobsbaai (west coast) was compared with crude protein levels (measured as %N x 6.25). Total protein was extracted and quantified using the Bradford method. No significant difference in carbon content was found between seasons for E. maxima but there was a significant difference in average carbon content between E. maxima (30.79 %) and L. pallida (27.79 %). No seasonal pattern was observed in the nitrogen content, and hence crude protein content, of E. maxima (seasonal crude protein averaged 7.8% of dry weight) and there was no significant difference found between E. maxima and L. pallida (crude protein averaged 9. 05% of dry weight). There was no significant seasonal difference in total protein (averaged 0.99% of dry weight) and no significance found between species. The reported better FCR in abalone feed comprised of E. maxima rather than L.pallida, if correct, is likely to be related to higher carbohydrate content (measured here as carbon) and not to higher protein content. E. maxima differs from L. pallida with regards to carbon storage, but not protein content
- ItemOpen AccessBenchmarks for the future: long-term vegetation change derived form palaeoecological techniques in West-Coast Renosterveld, South Africa(2014) Forbes, Cherie Janine; Gillson, Lindsey; Hoffman, TimmThis study focuses on long-term vegetation changes in West-Coast Renosterveld in the winter rainfall zone of the Cape Floristic Region (CFR), Western Cape, South Africa. Renosterveld is an evergreen, fire-prone Mediterranean-type shrubland consisting of asteraceous elements, grasses and geophytes. It is restricted to fertile, fine-grained soils and more than 90% of this vegetation type has been transformed by agriculture. High richness of endemic geophytes in particular gives remaining fragments an irreplaceable conservation value. Future climate projections for the region suggest a general warming of 1.5-3.5 °C, a 30-50% decrease in precipitation, an increase in drought periods and shorter rainy seasons with important consequences for the vegetation of the CFR. There is limited information regarding the response of Renosterveld to past climate change and land-use disturbance and there is much debate about the pristine composition of Renosterveld vegetation. The lack of Renosterveld environmental history with appropriate pre-colonial or pre-Iron age benchmarks makes it difficult to build evidence-based arguments for conservation management and restoration. Studying the history of Renosterveld in the late Holocene may provide information on responses to past warmer climates, and the more recent effects of anthropogenic disturbance. The aim of the present study was to reconstruct vegetation change, fire regime and changes in herbivory over the past ca. 1300 years at a West-Coast Renosterveld site in the Western Cape and to interpret these findings in light of known climate history and land-use change with a specific focus on the effects of disturbance by fire and herbivory. Findings were explored in relation to resilience theory, and the implications for conservation management and restoration. The following research questions were investigated. How has vegetation, fire and herbivory changed over time in West-Coast Renosterveld vegetation? How do changes in vegetation relate to climate and land-use disturbance and what are the main drivers of change? What are the links to theoretical frameworks such as resilience theory? Are recent changes unprecedented and is there evidence of a threshold response to climate and disturbance? (4) What are the implications of these findings for conservation management and restoration such as present day management of fire and herbivores?