Nematode parasites of the channids in Orogodo River, Southern Nogeria: Their relevance as bioindicators of anthropogenic pollution

Abstract

A survey of gastrointestinal nematode parasites of the channids, Parachanna obscura and Parachanna africana in the down reaches of Orogodo River at Evboesi, southern Nigeria was carried out between January and June 2011. A total of 112 fishes were examined out of which 72 (64.3%) were infected with gastrointestinal nematode parasites. The prevalence of infection reveals that Parachanna obscura had 62.5% while Parachanna africana had 66.7%. The nematode parasites recovered were Cucullamus sp., Camallanus sp. and Procamallanus laevionchus. The overall parasitic burden reveals that the prevalence infection was statistically significant (p< 0.05) in the species examined. The distribution of infrapopulations of the parasites varied significantly with size class and weight of the fish peaking in most cases in larger size classes. The chemical parameters of the river water at this site showed the water to be stressed with high BOD and nutrients levels. The intensity of the parasites in the host fish agree with previous hypotheses suggesting that environmental pollution does affect parasite population.

Keywords: Parachanna obscura, Parachanna africana, biomonitoring, parasite intensity, Orogodo River

Journal of Aquatic Sciences 28 (1): 43-55 (2013)