Browsing by Author "Soutschka, Nadine"

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    Community-based resource use monitoring at the Olifants River Estuary
    (2014) Soutschka, Nadine; Sowman, Merle
    Small-scale fisheries are increasingly seen as complex socio-ecological systems, requiring alternative management approaches. These new approaches to natural resource management advocate the inclusion of resource users in all aspects of management, including monitoring. Research suggests that involvement of local resource users in resource monitoring is beneficial as it promotes local empowerment, community stewardship and contributes to social and resource sustainability. This study aims to contribute knowledge about the nature and effectiveness of a community-based fisheries monitoring system at the Olifants River estuary in South Africa and documents lessons learned. This research reports on the revision and revitalisation of an existing community monitoring program operating at the Olifants River estuary and presents the results of data gathered from this one year monitoring program. It also compares these results with data gathered from previous years when the monitoring system was operational. Finally, the strengths and weaknesses of the community monitoring system are discussed. A participatory research approach was followed by employing members of the Olifants River community as catch monitors and working closely with the fishers and monitors to better understand their perceptions of the strengths and weaknesses of the monitoring system. Findings of this research suggest that despite weaknesses in the community monitoring system, the data gathered provided useful information about the catch effort trends for the fishery for the year under consideration and also enabled some comparisons of selected fisheries indicators with previous data to be made. These comparisons suggest that catch per unit effort for the target species, harder (Liza richardsonii) is stable and there is no indication of overexploitation of this resource. A key weakness of the monitoring is that it is ad hoc and funding is insecure. Due to poverty levels in the community, local monitors may take up short-term employment opportunities in the community and thus neglect their monitoring responsibilities. This means that the data sets are not comprehensive. Key strengths include the fact that it is simple, cost effective and can be implemented by community members. Furthermore, local involvement in resource monitoring builds capacity and skills as well as local empowerment. Finally, this research contributes to knowledge that can inform the implementation of community monitoring programs proposed by the recently published Small-scale fishing policy of South Africa. Key Words: Small-scale fisheries; natural resource management; participation, community monitoring, local empowerment.
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    Open Access
    Does tree size matter? : giraffe influence on African savanna ecosystem properties
    (2010) Soutschka, Nadine; Bond, William J
    Trees alter the environment by affecting microclimate, soil properties and adding structural complexity to an otherwise single stratum system. It is known that the herbaceous understory of Savanna ecosystems is most productive at intermediate tree density, where the shade and nutrients from the tree are more influential than the competition with the tree. Tree density varies in savannas due to disturbances, such as fire and herbivory. Yet, disturbances do not only alter density but can affect entire tree structure. It has been found that chronic ungulate browsing influences whole tree size, as well as canopy size and shape. Giraffe in south of Kruger National Park browse heavily on Acacia nigrescens found on basalt-derived soils. I studied the influence of trees above the giraffe browse trap (>6 m) as opposed to trees in the browse trap (< 6 m) on savanna ecosystem properties. I compared grass biomass, soil moisture, soil organic matter, soil carbon and soil nitrogen beneath tall trees vs. short trees, as well as in the open vs. underneath trees. Ecosystem properties were estimated and compared between a giraffe impacted to a giraffe absent area. Giraffe impacted area overall yielded lower grass biomass, soil moisture, soil nitrogen and soil carbon. The consequence is a trophic cascade of events from increased giraffe decreasing fires and in tum increasing tree density and hence carbon sequestration. As giraffes replace a single large tree by several small trees, shows that their population size is key determinant of ecosystem properties.
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    Measuring the growth of the articulated coralline red algae Corrallina officinalis and Arthrocardia corymbosa, (Corallinaceae, Rhodophyta) using a fluorescent brightener
    (2010) Soutschka, Nadine; Anderson, Robert J; Bolton, John J
    Coralline algae are important components of the coastal marine ecosystem, making it crucial to understand influences on their production and their growth rate in general. A few attempts have been made to quantify coralline growth rate using various methods, however since they have been reported to be slow growers it is difficult to quantify their growth rate accurately. Calcofluor white is an optical brightener that can be used to stain cell walls of plants and has been used to stain articulated corallines in the field, which proved to be a useful and accurate method for measuring coralline growth rate. This study tested the use of Calcofluor white for measuring growth of articulated (geniculate) coralline algae found on the south-west coast of South Africa, and made a series of methodological tests on the use of the stain. The growth rate of Corallina officinalis and Arthrocardia corymbosa were compared by growing them in culture in aerated plastic bags at 15°C and 16 hr light:8hr dark. Only C. officinalis produced measurable growth in culture (0.08-0.09 mm day⁻¹). Further tests were carried out only on C. officina/is. Additionally, an attempt was made to stain C. officinalis in a rock pool, in situ. In culture, the exposure time to the dye was tested for effect on growth rate. Growth rates were similar after 8 days, but after 20 and 28 days thalli stained for 15 min grew significantly slower than those stained for 5 or 30 min. However, this effect seems to be caused by factors other than staining time (e.g. light or water movement in the culture bags). Growth in culture of C. officinalis was strongly effected by salinity: at 60% saltwater (±21 ppt) growth fell to 0.03 mm day⁻¹ , and there was no growth in 30% saltwater (±10 ppt). The effects of 3 preservation methods on staining in C. officinalis were also tested. The stain was unaffected by drying the thalli or preserving them in 5% formalin in seawater. Preservation in 70% alcohol/20% glycerol/IO% freshwater (a common method of preserving coralline for DNA analysis) reduced stain visibility, particularly when thalli had only been stained for 5 min. The study confirms that Calcofluor white is an effective fluorescent dye for staining coralline red algae. Furthermore, staining can be as short as 5 min and thalli can be preserved without affecting the stain, so that thalli can be stained in situ, preserved, and brought to the laboratory for measurement.