Écologie des monogènes ectoparasites de Phenacogrammus major (Boulenger, 1903) de la rivière Akono à Binguela (Région du Centre): Structure du biotope branchial et Distribution des infracommunautés

Abstract

Fish is subject to various parasites attacks which reduce their population. As remedy, it is important to conduct taxonomic and ecological studies of different fish parasites. Regarding Phenacogrammus major (Boulenger, 1903), the first studies on this spec ies revealed the presence of three monogenean gill parasites, namely, Annulotrema amieti Birgi, 1988; Annulotrema gabrioni Birgi, 1988 and Characidotrema spiropenis Birgi, 1988. The aim of this study is to investigate some ecological aspects of the various monogenean gills parasites of this Characidae in Akono River at Binguela locality. From April to September 2015, 72 fishes were captured and taken to the laboratory where the sex and length of each specimen have been determined. After counted the number o f gills filaments on a stereoscopic microscope, the monogenean species were observed and mounted, and then, identified using with the light microscope. Gill system of Phenacogrammus major in the Akono River at Binguela locality was heterogeneous: on one ha nd the number of the gills filaments was not distributed uniformly through different arches and hemibranches, on the other hand this system alters with the standard size of fish. Only two fishes were not parasitized. The remaining 70 fishes harbored 3109 monogeneans (5 to 153 parasites per fish). The monogeneans guild of P. major consists of six species: Characidotrema spiropenis, Annulotrema amieti, Annulotrema gabrioni, Annulotrema sp. 1, Annulotrema sp. 2 and Annulotrema sp. 3. The parasitic load was either low or very low. Except for Annulotrema sp. 3, all of individuals of this component community have been over-dispersed. Sex was found to have no effect on parasites distribution. The occupation model of gill arches by C. spiropenis was an equi-partition. A. amieti and A. gabrioni have been respectively more frequent on the second and the medians of gill arches. The infestation rate gradually increased with the host standard length.