Diversity of metazoan parasites of the African catfish Clarias gariepinus (Burchell, 1822) as indicators of pollution in a subtropical African river system

Abstract

The relationship between parasite species diversity and organic pollution in the upper Manyame catchment, Zimbabwe, was investigated between October 2006 and January 2007. The parasite assemblage comprised 13 species in total. Species richness in the unpolluted sites was high; in the moderately polluted sites, it was low, while in the polluted sites, only one parasite species was encountered. Component community diversity, as measured by the Shannon index (H 0 ), decreased with increase in organic pollution. The distribution and occurrence of ectoparasites (Dolops ranarum, Lamproglena clariae, Chonopeltis sp. and Macrogyrodactylus sp.) and one endoparasite (Lytocestus sp.) were limited to the unpolluted sites, demonstrating their sensitivity to organic pollution. The prevalence of the nematodes Paracamallanus cyathopharynx, Procamallanus laevionchus and Contracaecum spp. larvae decreased along the pollution gradient, showing their high sensitivity to organic pollution. The platyhelminths Diplostomum sp. and Polyonchobothrium clarias were the most tolerant and occurred at both polluted and unpolluted sites. Proteocephalus sp. and Caryophyllaeus sp. were limited to the polluted sites, probably as a result of high abundance of oligochaetes and copepods, their intermediate hosts that thrive in sewage-enriched sediments, at the downstream sites. The observed results assume that the decrease in parasite diversity can be related to increased organic pollution. Some parasites requiring complex life histories were absent along with pollution-related disappearance of their vector hosts. Further studies should address the identification of parasite life stages that are more sensitive to pollutants.

Impact ofLernaea cyprinaceaLinnaeus 1758 (Crustacea : Copepoda) almost a decade after an initial parasitic outbreak in fish of Malilangwe Reservoir, Zimbabwe

“…Anchor worm infections usually result in a single parasite per host fish in flowing rivers and streams, causing a little damage, but in closed environments severe infestations often result (Demaree, 1967). The complex life cycles that parasites possess make them extremely valuable information units on aquatic environmental conditions since their presence or absence tells us a great deal about not only their host ecology but also food web interactions, biodiversity and environmental stress (Madanire- Moyo and Barson, 2010). Combining different species based on shared patterns of transmission provides a potentially more powerful indicator of prevailing environmental conditions (Moyo et al, 2009;Madanire-Moyo and Barson, 2010).…”

“…The complex life cycles that parasites possess make them extremely valuable information units on aquatic environmental conditions since their presence or absence tells us a great deal about not only their host ecology but also food web interactions, biodiversity and environmental stress (Madanire- Moyo and Barson, 2010). Combining different species based on shared patterns of transmission provides a potentially more powerful indicator of prevailing environmental conditions (Moyo et al, 2009;Madanire-Moyo and Barson, 2010). Knowledge on the fish parasites in Zimbabwe is limited to studies that were done in Lake Kariba (Chishawa, 1991;Douellou, 1992), in the upper Manyame catchment including Lake Chivero (Barson and Marshall, 2003;Barson, 2004;Madanire-Moyo and Barson, 2010;Taruvinga, 2011) and the south-eastern lowveld rivers (Barson et al, 2008a).…”

“…Combining different species based on shared patterns of transmission provides a potentially more powerful indicator of prevailing environmental conditions (Moyo et al, 2009;Madanire-Moyo and Barson, 2010). Knowledge on the fish parasites in Zimbabwe is limited to studies that were done in Lake Kariba (Chishawa, 1991;Douellou, 1992), in the upper Manyame catchment including Lake Chivero (Barson and Marshall, 2003;Barson, 2004;Madanire-Moyo and Barson, 2010;Taruvinga, 2011) and the south-eastern lowveld rivers (Barson et al, 2008a). No meaningful work has been done on fish parasites in small dams except work carried out by Barson et al (2008b) in Malilangwe Reservoir, Moyo et al (2009) in Insukamini Dam andTaruvinga (2011) in Harava and Seke Dams.…”

Assessment of Heavy Metal Pollution and Fish Parasites as Biological Indicators at Arabian Gulf off Dammam Coast, Saudi Arabia

“…Res., 11 (5): 198-206, 2015 Barson, 2010). Therefore, ecological parameters such as the prevalence and intensity of infection with different parasites have been applied to demonstrate faunistic differences between polluted (influenced) and non-polluted sampling sites Madanire-Moyo and Barson, 2010).…”

Prevalence and seasonal variation of ectoparasites in cultured Nile tilapia Oreochromis niloticus in Saudi Arabia

“…Prevalence, intensity and the relative abundance of fish parasites can be used as a marker of environmental stress. Ectoparasites are in contact with water they will be less in abundance if they are sensitive to pollution (Madanire-Moyo and Barson 2010).…”