Thermal studies on three common mangrove-associated ectotherms in Mngazana Estuary, with emphasis on the survival of the salt marsh crab, Parasesarma catenatum (Ortman 1897
- Authors: Nonyukela, Asandiswa Simamkele
- Date: 2020-02
- Subjects: Mangrove forests
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20838 , vital:46627
- Description: Ecological data on the development and distribution of mangroves over time suggest that mangroves were strictly tropical in nature but have extended to higher latitudes during warmer periods. Species distribution models show that the mangrove range may have since 1963 expand by 17 km in 2020 and by as much as 68 km southwards by 2050. More climate data obtained, and modelling of future climate have increased interest in the thermal tolerance or organisms. Critical thermal maxima (CTMax) and thermal tolerance were employed to determine the thermal limits of common estuarine species associated with the mangrove forests at Mngazana Estuary. Three species were selected, each representing a medium within the mangrove environment: for water, i) Palaemon peringueyi; ii) for air, Cerithidea decollata; and iii) Parasesarma catenatum on the substratum. Animals were acclimated for 48 hrs following the thermal history of the environment. Each individual was exposed to constant rate of water temperature increase of 1°C.h-1. Different size classes (adult, sub-adult, juveniles) of crabs were used to determine the CTMax performance. Parasesarma catenatum showed intraspecific variability in CTMax in both air and water. Palaemon Peringueyi had a CTMax value of 33.8°C±1.96 while C. decollata had a CTMax of 39.6°C±2.76 and P. catenatum had a CTMax of 36,38 ±1,57 in water and 34,1 ±1,67 in air. Different size classes (Adult, Sub-adult, Juveniles) of crabs were used to further determine their CTMax performance. Parasesarma catenatum showed of intraspecific variability in CTMax in both air and water. Juvenile crabs showed higher CTMax in water than in air, while adult and sub-adults showed a higher CTMax in air. The size classes of P. catenatum (Adult, Sub-adult, Juveniles) were exposed to a range of salinity treatments from 5-65 for both shock and acclimated exposures. For acclimated exposures, crabs were acclimated down/up at change of 5-10 untill the test salinity was reached, at which point the crabs were exposed. For the shock exposure, the crabs were directly exposed to the test salinity from the holding salinity of 35. This study shows P. catenatum is euryhaline, tolerating salinities been 10 and 50. Survival was highest across all cohorts for the short-term (shock) exposure, suggesting prolonged exposure to hypo/hypersaline conditions may be detrimental for this keystone Mngazana Estuary species. Juven.ile populations showed the highest survival rate for both shock and acclimated exposure. This study highlights the importance of microhabitat variability and its effect on the tolerance of different species to abiotic factors and so may be useful in modelling the effects of climate change in these systems. , Thesis (MSc) (Zoology) -- University of Fort Hare, 2021
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- Date Issued: 2020-02
Chemical evaluation, in vitro ruminal dry matter (DM) degradability and ruminal biological activity of common browse tree fruits of Alice
- Authors: Sondzaba, Bavuyise
- Date: 2020-01
- Subjects: Ruminants
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20882 , vital:46695
- Description: The objective of this study was to investigate the effect of species variations on chemical composition and in vitro ruminal degradability of Vachellia karroo, Grewia Occidentalis, Diospyros Lycioides and Ziziphus Mucronata fruits harvested from communally grazed lands in Alice, Eastern Cape Province, South Africa. The browse fruits were collected between February and May and analysed for crude protein (CP), dry matter (DM), ash, neutral detergent fibre (NDF), acid detergent fibre (ADF), organic matter (OM) and acid detergent lignin (ADL), condensed tannins (CT), macro minerals (Calcium (Ca), Magnesium (Mg), Potassium (K), Sodium (Na) and Phosphorus(P)) and micro minerals (Ion (Fe), Zinc (Zn), Manganese (Mn) and Copper (Cu)). There was significant variation (P<0.05) in chemical composition between browse fruits. The CP content differed significantly amongst the browse fruits, but all contained enough to meet the maintenance requirements of ruminants. Fruits from V. Karroo had higher (P<0.05) CP (182.26 g/kg DM), DM (896.50 g/kg DM) and ash (55.60 g/kg DM) contents compared to other browse species, while D. Lycioides fruits had higher (P<0.05) OM (951.60 g/kg DM) content than other browse fruits. Fruits harvested from G. Occidentalis had higher (P<0.05) ADF (513.27 g/kg DM), NDF (577.22 g/kg DM) and ADL (223.20 g/kg DM) content compared to other browse fruits. Fruits from V. Karroo had higher (P<0.05) CT (269.33 g/kg DM) content followed by Z. Mucronata (187.46 g/kg DM), while D. Lycioide (54.22 g/kg DM) and G. Occidentali (66.65 g/kg DM) had the same CT contents (P>0.05). There was a significant variation between browse species in macro and micro mineral contents. Fruits from G. Occindelis (43.93 g/kg DM) and V. Karroo (43.44 g/kg DM) had higher (P<0.05) Ca content compared to Z. Mucronata (24.06 g/kg DM) and D. Lycioides (20.06 g/kg DM). Ziziphus Muronata had higher (P<0.05) P (1.96 g/kg DM) content than other browse fruits. Fruits form V.karroo had higher Mg (4.75 g/kg DM), K (11.50 g/kg DM) and Na 3888 g/kg DM) content compared to other browse species. Fruits from V. Karroo showed significantly higher micro mineral content compared to other species. In terms of dry matter degradability (DMD), incubation time had an apparent effect on degradability of browse fruits except at 4 hours. The DM degradability increased with the increase of time and after 48 hours DMD was found to be satisfactory since it was above the prescribed 40 to 50 percent. However, the presence of condensed tannins had an effect on ruminal degradability of browse fruits. It was concluded that browse fruits have the potential to be used as protein supplements during the dry season since they contain moderate levels of crude protein. However, caution should be taken when feeding these browse fruits since they contain condensed tannins that affect rumen degradability. , Thesis (MSc) (Chemistry) -- University of Fort Hare, 2021
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- Date Issued: 2020-01
The role and function of traditional healing in families living in the Eastern Cape Province, South Africa: an afrocentric understanding.
- Authors: Sandlana, Nonkululeko Sheilla
- Date: 2019-06
- Subjects: Traditional medicine--South Africa , Healing , Family psychotherapy
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21267 , vital:47453
- Description: Traditional healing, alternately called traditional medicine or complementary and alternative medicine (CAM), has been in existence for a long time and sometimes used alongside popular western healing methods (Kirmayer, 2004). The focus of the current study was on the role and function of traditional healing infamilies living in the Eastern Cape Province. Through an Afrocentric lens, the study sought to explore the manner in which traditional healers helped family members deal with difficult life situations. The researcher used an explorative, descriptive, qualitative design, through focus group discussions, in-depth interviews and observations. Selection of participants was done through purposive sampling. The participants were heterogeneous in terms of age, gender, level of education, occupation and religion. Data analysis was employed through Interpretive Phenomenological Approach using Afrocentric theory as a metatheory and Ubuntu and sociocultural theory as complementary theories to understand the participants’ perceptions and experiences of the role played by traditional healing in building family resilience. Ethical principles were adhered to, for example voluntary participation and informed consent. Research findings revealed a variety of traditional ritual performances which embraced principles of Afrocentricity and Ubuntu – interconnectedness, interdependence and collectivism, spirituality, good communication and social support – as key elements in traditional family relationships. The traditional healers played a significant role in mentoring family members and mending broken families and alleviating suffering. They do this in line with the convictions of the ethical principles concerning respect cultural beliefs and values of consumers of psychological servises. Since the study was conducted in a rural area with isiXhosa speaking family members, there is a need for inclusion of other racial groups and family members living in urban areas. , Thesis (PhD) (Psychology) -- University of Fort Hare, 2021
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- Date Issued: 2019-06
Morphodynamics of headland bypass dunefields, with special reference to the Cape St Francis headland, Eastern Cape, South Africa
- Authors: Burkinshaw, Jennifer Ruth
- Date: 1998-01
- Subjects: Sand dunes -- South Africa -- Eastern Cape -- Cape St Francis
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52814 , vital:44206
- Description: The temperate Cape south coast, South Africa, is characterised by a series of log-spiral bays bound by low-relief rocky headlands. In South Africa corridors of transverse dunes crossing the headlands are referred to as headland bypass dunefields (HBDs). Sand blown off upwind beaches is transported across the headlands towards the downwind bays, bypassing the littoral route around the headlands. The key to the development of the HBDs is the presence of sandy beaches upwind of the headlands which lie athwart the prevailing winds. The low relief of the headlands and their shoreline configuration, coupled with their exposure to the marine wind regime, are such that the predominant high energy, westerly winds blow directly onshore. The local longshore drift system plays a critical role in replenishing beach sand deflated by the wind. The "type" HBDs occur in the Eastern Cape on the prominent Cape St Francis and Cape Recife headlands where HBDs have been active since at least the Mid to Late Pleistocene. The dunefields have length/width ratios ranging from 3 to over 10. Sand coverage within HBDs is metasaturated, i.e., the transverse dunes are separated by well-defined interdune areas. Average dune height in the larger dunefields in the Eastern Cape is 9-10 m. The HBDs are commonly bound by sidewalls that develop along the interface between the dunefields and vegetation. The stabilised sidewalls provide the most prominent record of former HBD activity and can influence subsequent HBD morphology. The Oyster Bay dunefield on the Cape St Francis headland was chosen for a study of the aeolian morphodynamic processes that operate within these systems. The dunefield currently operates over a distance of about 14 km and a width of 500 - 1200 m; it is at present cut off from its sand source. Shallow lakes develop in the interdune areas after periods of high rainfall. A 2 week airflow study recorded wind speed along the prevailing wind axis of the Oyster Bay dunefield during spring 1990. Wind speed increased significantly downstream until at least the mid-dunefield area during both the prevailing westerly and seasonal easterly winds. The downwind wind speed increase can be partially attributed to topographic acceleration of airflow as it is compressed over the low cape. The extent of the wind speed increase can vary depending on the land/sea temperature contrasts and the temperature structure of the lower atmosphere. Wind speed recorded across the width of the dunefield was slowed down along the margins by vegetation, while a faster core moved down the centre of the dunefield. Rates of dune movement along the prevailing wind axis show a general correspondence between the volume of sand transported eastwards in different areas of the dunefield and the airflow pattern down the length of the dunefield. Sand is transported most efficiently in the centre of the dunefield where westerly flow is at its maximum. Sand transport calculated from dune migration rates is about 50% of potential sand transport calculated from wind data, as flow is metasaturated. Flow off sandy beaches may be naturally below saturation owing to the effect of intertidal moisture and salts binding the sand. In the Eastern Cape metasaturation can be further enhanced by the downwind entrapment of sand by vegetation along the dunefield margins and within wet interdune areas. The 2-dimensional model for bedform development within HBDs focuses on the downwind extension of the dunefields and transmission of sand through the systems. The combination of the high transport capacity of the wind downwind and metasaturated flow maintains the transport of sand across headlands. HBDs operate aerodynamically as erosional or sediment bypassing systems although deflation of the wet interdune areas is limited. Fully functional short HBDs are the most likely to operate with neutral sediment budgets. Long systems are more susceptible to spatial and temporal effects that modify the sandflux through the systems and hence the outflux from the systems. The Oyster Bay dunefield operates with a mildly positive sediment budget because of sediment entrapment downwind. The morphology and morphodynamic behaviour of HBDs is in contrast to that of the tabular transgressive dunefields that form parallel to the shores of the large log-spiral bays of Algoa Bay and St Francis Bay. The existing morphological classification of transgressive dunefields needs to be revised to include headland bypass dunefields. Keywords: headland bypass dunefields, transgressive coastal dunefields, aeolian morphodynamics, Cape St Francis, Cape south coast. , Thesis (PhD) -- Faculty of Science, 1998
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- Date Issued: 1998-01
Population structure, production, growth, reproduction and the ecology of Atherina breviceps Valenciennes, 1935 (Pisces : Atherinidae) and Gilchristella aestuaria (Gilchrist, 1914) (Pisces : Clupeidae), from two southern Cape coastal lakes
- Authors: Ratte, Theodore Wilhlelm
- Date: 1989-01
- Subjects: Silversides , Clupeidae -- South Africa -- Cape of Good Hope
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/50878 , vital:43029
- Description: Over the period October 1978 to January 1981, a total of 147 853 Atherina breviceps with a total biomass of 55 2B0,7 g and 107 046 Gilchristella aestuaria with a total biomass of 33 708,9 g were collected in the Swartvlei System and 151 531 A. breviceps with a total biomass of 727 795,0 g and 51 258 G. aestuaria with a total biomass of 12 231,5 g were collected in Groenvlei, to determine their population structure, production, growth, reproduction and ecology in both systems. A. breviceps and G. aestuaria were collected from nine and eleven estuaries respectively, including Groenvlei, along the Cape coast to determine the degree of genetic divergence of both these two species in Groenvlei. It was found that the mature 0-year-old A. breviceps and the 2-year-old G. aestuaria dominated the catches in the Swartvlei System, whereas the juvenile 0-year-olds and 1-year-olds of both species respectively, dominated the catches in Groenvlei. The Swartvlei System and Groenvlei produced respectively between 10-12 metric tons of A. breviceps and between 5-3 metric tons of G. aestuaria annually. A. breviceps and G. aestuana in the Swartvlei System and Groenvlei attain observed ages of between 3 years and 7-8 years respectively. The main spawning period for both species is between spring-autumn in Groenvlei and for A. breviceps in the Swartvlei System. G. aestuaria has a continuous winter-summer spawning in the Swartvlei System. A. breviceps and G. aestuaria in Groenvlei have diverged to such an extent from these two species' populations in other systems, that A. breviceps and G. aestuaria in Groenvlei should receive a priority conservation status. , Thesis (PhD) -- Faculty of Science, 1989
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- Date Issued: 1989-01
The biology of the sand shark Rhinobatos Annulatus, in Algoa Bay with notes on other elasmobranchs
- Authors: Rossouw, Gideon Johannes
- Date: 1983
- Subjects: Sand sharks , Guitarfishes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52802 , vital:44061
- Description: The biology of the lesser sand shark, Rhinobatos annulatus, was studied off sandy beaches in Algoa Bay over a period of two years. Tagging studies, due to low numbers tagged, did not reveal major movements. However, comparison of numbers of sand sharks caught off the beach and deep water during summer and winter months suggested that migration occurred during these seasons with the animals being inshore in summer. Annual rings on the vertebral centra were used to determine age. Both sexes can reach a maximum age of seven years. Conventional growth curves could not be fitted and empirical curves were used to illustrate growth. The reproductive cycle was investigated and indicated that both sexes matured after three years of age. The breeding season was during late summer when the shallow water was utilized as a nursery area. The sand shark is an aplacental viviparous species with a gestation period of 10 months. Breeding occurred every year and fecundity increased with total body length to a maximum litter size of 10 young. The most important prey items taken inshore were the mysid Gastrosaccus psammodytes, the prawn Macropetasma africanum, the crab Ovalipes punctatus and the sand mussels Donax spp. Differential predation by different length classes of sand shark resulted from a dynamic zonation of these different size classes in the surf zone. Smallest individuals fed closest inshore. Seasonal variation recorded in the hepatosomatic index was primarily due to the accumulation of hepatic lipids. This variation showed significant correlations with the breeding cycle in adult sand sharks. The contribution of liver lipids to the formation of egg yolk was estimated and found to be secondary to lipid reserves for maintenance. Liver colour varied depended on the amount of liver lipids. Ancillary observations were made of other elasmobranchs in the surf zone. , Thesis (DPhil) -- Faculty of Science, 1983
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- Date Issued: 1983