Bibliography: leaves 73-76. / A form of the southern African plant Asparagus asparagoides (Asparagaceae), is a serious environmental week in Australia, where it is known as bridal creeper. Bridal creeper has an extensive underground tuber system and can invade native vegetation, two factors that make chemical and/or mechanical control difficult. The fruit is bird dispersed which facilitates colonisation of new sites. Surveys for potential biological control agents for use against bridal creeper in Australia were initiated in South Africa during 1989. This dissertation describes the identification, distribution and phenology of A. asparagoides in South Africa, as well as the natural enemies associated with the plant and their potential for use as biological control agents in Australia. Potential biological control agents that attack vegetative growth of bridal creeper included an undescribed Zygina sp. (Cicadellidae), two undescribed Crioceris species (Chrysomelidae - Criocerinae) and the rust fungus, Puccinia myrsiphlli DC. (Uredinales). The seeds of bridal creeper are attacked by an undescribed Eurytoma sp. (Eurytomidae) and the fruits by Zalaca snelleni (Wallengren) (Noctuidae). An organism directly attacking the tuber mass of bridal creeper was not found. Experimental results illustrated that herbivore damage to the above ground parts of the plant resulted in reduced tuber mass and also impacted negatively on fruit production.

Some silvicultural practices in the Knysna Forest are aimed at the sustained-yield production of valuable timber tree species, albeit on limited areas only. This study investigates effects of forest plant species composition and physiognomy on bird and invertebrate communities in three discrete, relatively undisturbed forest types along a dry-wet soil moisture gradient. Using discriminant functions analysis, a 100% floristic and a 78% vegetation structural discrimination was obtained between the three forest types. However, the bird communities of these floristically and structurally different forest types were very similar in species composition and had much lower densities than normally encountered in other superficially similar forests. It was only possible to discriminate between the wet and the moist/dry forest types by using the two best bird discriminators. the blackheaded oriole (Oriolus larvatus) and the sombre bulbul (Andropadus importunus). A separation of the moist and dry forest types was not possible. Although an 81% discrimination between forest types was attained through analysis of ground surface invertebrates. measures of litter and aerial invertebrate abundance were of limited use as discriminators. Historical and biogeographic factors and the low nutritional levels in the soil and vegetation may be the cause of low bird and invertebrate density and diversity. It is concluded therefore, that floristics and vegetation structure have, at best, a minor influence on bird community structure, and possibly also on the invertebrate community in the Knysna Forest and that management practices need not cater for variation in forest vegetation composition and physiognomy. Bibliography: pages 49-59.

Includes bibliographical references. / This study is the first documentation of ciliate epibiont-host associations in the Western Cape Province of South Africa. Benthic macroinvertebrates were sampled from six rivers in the Western Cape Province (Wolwekloof, Wit, Rooielskloof, Molenaars, Elandspad and Eerste) to determine epibiotic prevalence and to explore relationships between prevalence and host abundance. Ciliate morphology and 18S rDNA and ITS region sequence data were used to identify the different taxa present, and attachment preferences of epibiont colonies for host body part were determined. The response of ciliate epibionts to water pollution along a pollution gradient in the Eerste River was examined to assess their potential as bioindicators of water pollution.

Includes abstract. / Includes bibliographical references. / This study describes the identification of three novel precursor transcripts which includes the adipokinetic hormone (AKH) / red pigment-concentrating hormone (RPCH) and the neuroparsin (NP) from the South African spiny lobster, Jasus lalandii, the RPCH and the RPCH receptor (RPCHR) from the water flea D. pulex and the NP from the southern green stinkbug, Nezara viridula. The study also investigates the localisation and expression profiles of the AKH/RPCH and NP transcripts within crustaceans and insects.

Includes bibliographical references. / Habitat alteration, primarily associated with human expansion and consumption, has been identified as the leading threat to biodiversity worldwide. The net result of an ever increasing human population is the loss of available habitat to species, affecting individual survival, together with the fragmentation of habitat across a landscape, resulting in an increased chance of a genetic bottlenecks and localized extinction. Although many organisms are experiencing the deleterious effects of these processes, amphibians appear to be suffering more than other vertebrate groups. One species that has experienced significant impact through habitat alteration and urbanization is the Western Leopard Toad (Bufonidae: Amietophrynus pantherinus). In the south-western portion of the Western Cape Province, South Africa, the population is large and genetically diverse with numerous potential breeding sites. However, extinctions in the disjunt eastern area, where there are a low number of known breeding sites (currently 7 identified), have raised concern over the conservation of this management unit. In this study radio-telemetry and population genetic data were used to investigate fine scale, short term migration patterns in Western Leopard Toads to specifically assess the role of agricultural land-use and habitat fragmentation on long-term dispersal dynamics.

Includes abstract. / This thesis focused on developing an approach for prioritising Bird Species of Special Concern for conservation and monitoring action within the South African National Parks (SANParks). SANParks is in the process of developing a Species of Special Concern Monitoring Programme (SSC MP) which forms part of the larger SANParks Biodiversity Monitoring System. Birds are known to be good indicators of biodiversity for a number of reasons.

Includes abstract. / Includes bibliographical references (p. 32-35). / Algal and invertebrate assemblages resident on abalone (Haliotis midae) shells at two subtidal locations in the western Cape of South Africa were investigated. Forty medium-sized (linear length 10 - 20 cm) abalone were harvested (along with forty complementary rock-face quadrat samples) from one site at Cape Point and two sites at Gansbaai and the resident species were identified and statistically compared.

The occurance and distribution of astaxanthin in tissues of the spiny lobster, Jasus lalandii was investigated. The concentration of astaxanthin was quantified in the exoskeleton, haemolymph, muscles, gonads and hepatopancreas as well as in egg parcels from berried females during the moult as well as the reproductive cycles. Astaxanthin was the dominant carotenoid in all tissues, but small amounts of other carotenoids were detected. Exoskeleton, ovaries and extrude egg parcels had significantly higher astaxanthin concentration than haemolymp, muscles and hepatopancreas. This distribution of astaxanthin was found in both captive and free-living spiny lobsters. Free-living spiny lobsters generally had higher astaxanthin concentration than the captive spiny lobsters although the data is not statistically significant in all tissues investigated.

Word processed copy. / Includes bibliographical references (p. 80-89). / The aims of this thesis are to estimate how many marine species remain to be described in this region and which areas are most in need of additional sampling effort.

Bibliography: leaves 120-134. / Phosphorus is one of the most important nutrients in aquatic environments because of the role that it plays in eutrophication. Increased amounts of phosphorus stimulate excessive growth of nuisance plants, which have negative impacts on waterbodies. Urban runoff and sediment fall under various sources of phosphorus. Sediments act as sources as well as phosphorus storage tanks. Processes of adsorption and desorption which occur -at the sediment water interface make phosphorus available for excessive plant growth. Information relating to these processes, and other limnological processes, serves as a guideline to the understanding of the courses and methods of control of eutrophication. In the study of phosphorus dynamics in Rondevlei, a small eutrophic lakelet in southern Africa, five stations were monitored during spring, summer, autumn and winter of 1988. Temperature, oxygen, electrical conductivity and pH were determined in the field. Soluble Reactive Phosphorus (SRP), calcium (Ca), Total Dissolved Solids (TDS), Total Suspended Solids (TSS) and Particulate Organic Matter (POM) were measured in the laboratory.