Some biotic and abiotic factors which influence the distribution of monogeneans in the gills of Brycinus kingsleyae günther, 1986 (Osteichtyes-Alestidea) from the Nyong river at Akonolinga (Centre-Cameroon)

Title : Some biotic and abiotic factors which influence the distribution of monogeneans in the gills of Brycinus kingsleyae günther, 1986 (Osteichtyes-Alestidea) from the Nyong river at Akonolinga (Centre-Cameroon)

Abstract:

The Alestidae or African Characins form the most represented family among the Characidea. These fish have a very important place in the diet of the riverside populations of the rivers in which they abound. The culture of fish of this family proves to be essential to ensure the necessary contributions of all these populations unable to obtain imported fish. One difficulty that arises in the cultivation of these species is their great parasitism coupled with their fragility in culture.

Monogeneans are among the fish parasites that cause the most damage in the rearing environment. This is particularly about their direct and simple cycle and their mode of nutrition. The works carried out in Cameroon on the Alestidae are essentially focused on the systematic aspect. That present work was undertaken to determine some biotic and abiotic factors which influence the parasitic distribution of the gills monogeneans of Brycinus kingsleyae Günther, 1986  from the Nyong River.

From december 2017 to december 2018, each month thirty specimens of B. kingsleyae were caught with a gill net by a local fisherman. Each fish was then preserved in 10% formalin. In the laboratory, after a determination of the sex and the standard length of the fish, each gill was detached and placed in a Petri dish marked left or right and containing tap water. Using a stereomicroscope, the number of gill filaments was counted and using a mounted needle, each parasitic individual was isolated and mounted between slide and coverslip in a drop of water. The different species were identified under an optical microscope with the help of drawings of the sclerotized parts made by Birgi (1988).

It emerges from this  work that: 1°) Five species of monogeneans used the gills of B .kingsleyae is :Annulotrema combesi Birgi, 1988, Annulotrema maillardi Birgi, 1988, Annulotrema nyongensis Birgi, 1988, Annulotrema bouixi Birgi, 1988  and Chracidotrema regia  Birgi, 1988;  2°) All these species are principal; 3°) The structuring of the infracommunities follows the same model as that of the gills filaments which is A₂ >  A₁ = A₃ > A₄ ; 4°) it is during the rainy season that the prevalence and mean intensity are the highest; 5°) the parasitism is not modified by sex and size of the host.

This work is therefore not only a good model for ecological studies but also a first step for the implementation of cultivation and conservation measures for Alestidea.

Key words: A. bouixi, A. combesi, A. maillardi, A. nyongensis, B. kingsleaye, ecology, C. regia, infracommunity, Nyong, monogeneans.

What will audience learn from our presentation?

• This study makes it possible to determine the appropriate sampling periods for a fish farm of B. kingsleyae
• This study is a first step for the establishment of a means of conservation of some African freshwater species
•    By this study, we can establish some models of species distribution in ecology
• Improvement of dietary condition (protein intakes) of the riparian populations of Cameroon and Africa

Biography:

Ph.D. student NDONGO Ivan Studied Biology of Animal Organisms at the University of Yaoundé I, Cameroon. He Joined the Research group of Prof TOMBI Jeannette at the Department of Animal Biology and Physiology at the same institution in 2015. He received Master degree in Parasitology and Ecology (specialized in Ichtyoparasitology) in 2018 and actually makes his thesis work in monogeneans parasite of some African tetras. The objectives is to improve the farm of African fishes to improve dietary condition of poor people of Cameroon and Africa. She has published 02 articles as first author in SCI (E) journals.