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Molluscs are an important component of South Africa’s biodiversity. The assessment of distribution patterns and factors influencing the biogeographic distribution are an integral part of assessing the conservation status of molluscs and their conservation management needs. The existing terrestrial mollusc data from South Africa were assessed in terms of their value to biodiversity conversation planning and management. Although the data on terrestrial molluscs are incomplete and would be misleading in terms of identifying specific areas for protection, the data do illustrate significant patterns and trends of mollusc endemism and diversity, which can be used to improve biodiversity conservation and management efforts. The distribution of molluscs across the South African landscape illustrated ten broad biogeographical patterns. Two of these patterns reflected ancient distribution patterns of molluscs and consisted of molluscs of the Gondwanaland/southern relict and Laurasian origins. Three biogeographic patterns occurred across the eastern regions. These patterns were defined as the tropical/subtropical east African, subtropical east of southern Africa and east African afromontane patterns. The biogeographic patterns in the west consisted of the characteristic temperate ‘Mediterranean’ Cape centre and the arid regions of northwestern Cape, Namibia and parts of Botswana. An additional biogeographic pattern identified as the nama karoo/central west was recognised. The final two biogeographical patterns described taxa that were widely distributed and taxa that exhibited disjunct distributions. Twenty-six families and forty-three genera were associated with more than one biogeographical pattern. The dominant biogeographic pattern was the tropical/subtropical east African component. Twenty-one families and forty-eight genera were associated with this biogeographical pattern. The east African Afromontane pattern was also a conspicuous biogeographic element in South Africa. Fewer families and genera were distributed in the western and central regions. The distributions of terrestrial molluscs were influenced by a combination of various factors, which included the presence of rivers, the escarpment, altitude, humidity, precipitation, temperature and biomes. Rivers could possibly restrict the distribution of certain mollusc taxa but did not appear to be the dominant factor that influenced the distribution of molluscs across the landscape. In terms of the effect of temperature on the distribution of molluscs, the mean daily and mean annual temperatures appeared to have more of an influence on the distribution patterns than the mean daily maximum and minimum temperatures. Mean annual temperatures influenced the distribution of all families and genera. The mean daily maximum temperature appeared to have little or no effect on the distribution of mollusc taxa. Humidity and biomes also appeared to influence the distribution of taxa. The least inhabited biome was the succulent biome. Many mollusc taxa occurred in the wetter, warmer areas with high humidity levels. Areas of high species richness and high endemic species richness in South Africa were identified using two systems of endemism, one based on distinctive gaps in the frequency distribution of terrestrial molluscs in South Africa and the other based on an existing classification of invertebrate endemism (Hamer & Slotow, 2002). Areas of high mollusc species richness and endemism were also compared to areas of high millipede species richness and endemism. The total number of South African mollusc endemics was 370 (83 % of 447 indigenous species). The dominant mollusc families in South Africa were Achatinidae, Charopidae, Streptaxidae, Subulinidae and Urocyclidae. The first system of endemism identified 56 site endemics (species with only one locality), 50 local endemics (0 < maximum distance < 60 km) and 145 regional endemics (60 km < maximum distance < 330 km). The Hamer & Slotow (2002) classification of endemism classed 67 species as site endemics (maximum distance between localities < 10 km), 47 as local (11 km < maximum distance < 70 km) endemics and 59 as regional endemics (71 km < maximum distance < 150 km). The analysis of mollusc data, with both systems of endemism, showed similar areas of high species and endemic species richness. Quarter-degree grid cells with highest species richness overlapped with grid cells with the highest number of endemic species. However these grid cells coincide with areas that have been intensively sampled and this bias limits the application of the data in conservation planning. The patterns of endemism for molluscs and millipedes within the provinces differed, indicating that the inclusion of a single taxon in conservation planning would inadequately reflect the diversity of invertebrates in South Africa. A preliminary list of specific priority endemic sites for terrestrial mollusc conservation was identified. It is essential that the existing data on invertebrates be evaluated and used to identify key patterns and trends in invertebrate diversity as this will allow for the inclusion of invertebrates in biodiversity conservation planning and management. The analysis of the existing mollusc data identified bio geographical patterns that are important to conservation planning both at the local and national level as well as commonalities and differences between molluscs and millipede distributions. The analysis also highlighted the importance of municipal areas for conservation of hotspots of diversity, particularly in the eastern coastal areas of South Africa. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2007.

Thesis (Ph. D.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf 215-251).

The natural product chemistry of six species of South African opisthobranch molluscs and some of their dietary marine invertebrates was investigated. Nineteen previously undescribed secondary metabolites and twelve known compounds were isolated and their structures determined by a combination of spectroscopic and chemical methods. The circumtropical sea hares Aplysia parvula and A. dactylomela were found to contain halogenated red algal metabolites. 3Z-bromofucin (120), the Z analogue of a known Laurencia CIS acetogenin, was isolated from A. parvula. A. dactylomela yielded a series of novel non-aromatic cuparanes, the algoanes (121-123), the novel tricyclic Iaurane ether ibhayinol (124) and three known chamigrane sesquiterpenes, prepacifenol epoxide (101), pacif-7-enediol (104) and nidificene (125). A variety of new octocoral sesquiterpenes were isolated from the endemic South African arminacean nudibranch Leminda millecra including algoafuran (150), cubebenone (151), 8-hydroxycalamenene (152) and a series of seven triprenylated toluquinones and toluquinols (153-159). L. millecra also yielded the known sesquiterpenes millecrones A (142) and B (143) and isofuranodiene (149). Twenty eight voucher specimens and eighteen crude extracts of South African octocorals collected by the Coral Reef Research Foundation were screened by GC and GC-MS and 142 was found in Alcyonium fauri, while 143, 151 and possibly 149 were present in Leptogorgia palma. An investigation of southern African chromodorids yielded the known macrocyc1e latrunculin B (220) and two new spongiane diterpenes (221) and (222) from Chromodoris hamiltoni, while the known spongiane diterpene (210) was isolated from the endemic nudibranch Glossodoris sp. 4. The endemic nudibranch Hypselodoris capensis contained the known furanosesquiterpenes nakafuran-8 (223) and -9 (224) and the known furanosesterterpenes variabilin (195), 22-deoxyvariabilin (225) and furospinosulin (227) together with the new variant 22-deoxy-23-hydroxymethylvariabilin (226). Compounds 223 and 224 were also found in a Dysidea sponge, while the furanosesterterpenes 195, and 225-227 were present in a Fasciospongia sponge upon which H capensis specimens were found. The Dysidea dietary sponge of H capensis also yielded a new aromatic sesquiterpene, tsitsikarnmafuran (266), whose structure was confirmed by the synthesis of two possible regioisomers.

Made available in DSpace on 2014-06-11T19:30:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-04-26Bitstream added on 2014-06-13T19:40:28Z : No. of bitstreams: 1 david_jao_dr_rcla.pdf: 933714 bytes, checksum: 206e3f9f14e600b5847ba3020cae58f0 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O estuário de Santos já foi um exemplo de degradação ambiental, porém medidas dos órgãos responsáveis pelo saneamento ambiental resultaram em melhoria na qualidade das águas, mas os sedimentos e a biota continuam contaminados. Os moluscos bivalves são bons bioindicadores de poluição ambiental, devido a seu hábito séssil e filtrador, e à capacidade de acumular diversas substâncias. Mytella falcata é uma espécie comum em regiões tropicais, encontrada semi-enterrada no sedimento, podendo fornecer dados sobre as condições do mesmo. Neste trabalho, bivalves da espécie Mytella falcata residentes em três pontos do estuário de Santos com diferentes níveis substâncias potencialmente poluidoras, foram analisado a fim de caracterizar a população residente nestes pontos. As técnicas utilizadas foram o ensaio do cometa, o teste do micronúcleo e a análise histopatológica das brânquias, incluindo técnicas histoquímicas, ultramorfológica e ultra-estrutural. As análises demonstraram que a espécie pode ser para avaliar danos genotóxicos, mutagênicos e citotóxicos. Utilizando o ensaio do cometa os indivíduos dos pontos B e C mostraram níveis significativamente maiores de danos ao DNA quando comparados aos animais do ponto A. Quanto a análise dos micronúcleos os animais de todos os pontos apresentaram resposta muito semelhante. A morfologia dos filamentos branquiais desta espécie mostrou-se muito similares a de espécies próximas e na análise histopatológica foram observadas alterações nos pontos B e C; as principais foram o desprendimento do epitélio da região lateral do filamento, modificação na morfologia deste epitélio, aumento na produção de muco e processos envolvidos na eliminação de células e renovação das mesmas. Os dados obtidos mostraram que todas as técnicas resultaram no diagnóstico de que os animais residentes no ponto... / The Santos estuary which is located in São Paulo, Brazil, was considered one of the major examples of coastal degradation. Nowadays the quality of this environment has improved, but the sediment and the biota are still contaminated. Bivalve mollusks are sedentary, filter-feeding invertebrates that have been widely used to monitor aquatic habitats. Mytella falcata is very common in tropical areas and lives buried in the sediment. In this study, the mussel Mytella falcata, from three sites of Santos estuary, were analyzed; the three sites presented different levels of harmful substances. The aim of this analysis was to characterize the animals that live in this area. The techniques applied were the comet assay, micronucleus test and histopathological analysis of the gill filaments, including the histochemistry and scanning and transmission electron microscopy. Laboratory tests demonstrated that the species can be used as bioindicator. The analyzed specimens from sites B and C, showed higher levels of DNA damage when compared to those from site A. The micronucleus test presented no difference between the three sites. Mytella falcata gill filaments showed high similarity to other Mytilidae species. The histopathological analysis demonstrated some alterations in sites B and C. The major alterations were the detachment of epithelial cells from the lateral surface, changes in the morphology of this epithelium, increase in mucous production and processes involved in cell elimination and renovation. The damages found in animals from sites B and C were considered as adaptations to the exposition to pollutants. The lack of difference between animals from sites B and C were related with the distance between animals and sediment. In conclusion, this study confirm that sediments act as a deposition site for pollutants and alert the authorities for the manner of dealing with this sediment... (Complete abstract click eletronic access below)