Insight into the diversity of parasites of Cyprinodontiformes (Pisces, Teleostei) from forest streams of South Cameroon, Central Africa, and their potential impact

In order to describe the parasite fauna of the Cyprinodontiform fishes from streams located in the forest zone of the central and south plateau and the littoral plain of Cameroon and to evaluate their potential impact on their hosts by analyzing community structures, the gastrointestinal tracts and the gills of 1019 specimens of 14 Cyprinodontiform fish species belonging to the genera Aphyosemion Myers, 1924 and Epiplatys Gill, 1862 were dissected and screened for the presence of parasites. Only 149 fish specimens were found to be infected by at least one of the parasite taxa recovered. On the whole, parasitic infections in cyprinodonts, perceived on the basis of prevalence and mean abundance indices, appeared to be very low, although the parasitic fauna of some host species as A. cameronense was diversified (up to seven species). Aphyosemion cf cameronense, A. koungueense and Aphyosemion sp. showed low abundances and appeared free of ecto-and endoparasites. As micropredators, cyprinodonts acquire these endoparasites through a variety of invertebrate preys and concentrate some infective parasite stages (such as metacercariae) of several definitive hosts that prey on them. This work showed that although nematodes and trematodes, which can develop high intensities or abundances in some fish specimens, might impact their hosts (especially females) and influence their population dynamics, parasitism in general seems not to regulate the communities of the cyprinodont fish species. (Résumé d'auteur