Browsing by Author "Mwita, Chacha John"

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    Diversity and abundance of the parasite fauna of the catfish clarias cariepinus (burchell, 1822) (clariidae from the Mwanza Gulf, Lake Victoria.
    (University of Dar es Salaam, 2002) Mwita, Chacha John
    A parasitological study was carried out on 1071 Clarias gariepinus individuals from the Mwanza Gulf, between September, 2000 and September, 2001. A total of 18 parasite species were recovered; 5 nematodes, 6 nematodes, 3 cestodes, the Monogenea, Hirudinea and Crustacea were each represented by one species. Of the 18 species, 10 were identified to species level, 7 to the genus and 1 to family level. Spinitectus petterae is reported for the first time in C. gariepinus in Tanzania, while Tylodelphys species are reported for the second time. The parasite communities investigated were rich and diverse at all localities sampled. D. mashonense, Tylodelphys species, P. clarias and P. cyathopharynx form the core-species in the parasite communities studied. Diversity increased with fish size but decreased in the largest fish and was high during the dry season and low in the wet season. Most of the fish harboured 1 or 2 parasite species. The community was dominated by autogenic species (13/18) with 5/18 being allogenic species. The abundance of five parasite species was significantly different among the three localities sampled. Prevalence and mean intensity of most autogenic parasites were high during the dry season while that of allogenic parasites increased during the rainy season. Prevalence and mean intensity increased with increasing size of C. gariepinus. Higher abundances of P. clarias and P. cyathopharynx affected the condition factor of C. gariepinus through feeding competition. Along the gut, parasites diversity values were high in the stomach and small intestine, while the other sections of the gut were dominated by monospecific infection. Factors structuring the parasite community of C. gariepinus of the Mwanza Gulf are discussed.
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    Students in the determinants of the parasites` community structure of the clariid fisheries in lake Victoria
    (University of Dar es Salaam, 2006) Mwita, Chacha John
    The clariids are catfishes that belong to the suborder Siluroidea and inhabit diverse habitats, are able to traverse long distances and are omnivorous in feeding habits. These feature parasite fauna. This study was s predispose the clariids to infection by a diverse parasite fauna. This study was design to investigate the factors that determine the structure. Specifically, the study investigated the phylogenetic relationships among the clariid species and their most common parasites based on comparative morphology and molecular characters. The study further analysed the host-parasite communities. The use of morpho morphometrics with multvariate statistics revealed that Clasias gariepinus is related to Clasias liocephalus, as is Clarias warneri to Clarias Aluaudi. phylogenetic analysis based on mitochondria cytochrome gene suggested the same relationship as in morph metric analysis. Molecular phylogenetic revealed that Heterobranchus longifilis is the oldest clariid in Tanzania and C. gariepinus is oldest in the Lake Victoria basin. Clariid species are estimated at 500,000 years old and 12 years old. Phylogenetic analysis of the metazoan parasites of clariid fishes based on the nuclear 18S rDNA gene delineated the parasites into their respective lineages. Host-parasite relationship using ``a strict co evolutionary`` constrained trees strongly suggested that the clariid fish hosts and their parasite fauna did not coevolve. Hence, it is concluded that parasite communities in clariid fishes studied are structured by host-parasite ecological factors. The host parasite attributes and ecological correlates of parasite species richness are therefore discussed.