Population Dynamics of Copepods (Lernaea Cyprinacea Linnaeus, 1758) Tilapia Parasites from the Senegal River-Mauritania

For a long time, humans have been exploiting fish resources to meet their needs mainly for food, as well as for fishing and aquaculture. The first aquaculture trials began before 4000 years ago in Egypt with the production of the famous tilapia fish [1]. It is a fish that lives in fresh water. It is of African origin and also populates the basins of Niger, Volta, Senegal and Congo. According to the FAO [1], in the Cichlid family, two species are mainly cultivated: the Mozambique Tilapia (Oreochromis mosambicus) and the Nile Tilapia (Oreochromis niloticus), which is raised in the ISET fish station. Rosso in Mauritania. Fish has always been an abundant and inexhaustible food. And the reality is completely different, we are faced with the fact that many stocks of freshwater fish are poorly known. In this case we proposed to study the effect of the biotic factors on tilapia parasitism that will be the size, the sex of the fish with an analysis of the prevalence, the intensity and the abundance parasites. Among the parasites determined, we opted for the analysis of the dynamics of populations of those most represented within the parasitic communities of the fish examined, such as: Lernaea cyprinacea Linnaeus, 1758 copepods parasitic fish Tilapia.


Introduction
For a long time, humans have been exploiting fish resources to meet their needs mainly for food, as well as for fishing and aquaculture. The first aquaculture trials began before 4000 years ago in Egypt with the production of the famous tilapia fish [1]. It is a fish that lives in fresh water. It is of African origin and also populates the basins of Niger, Volta, Senegal and Congo. According to the FAO [1], in the Cichlid family, two species are mainly cultivated: the Mozambique Tilapia (Oreochromis mosambicus) and the Nile Tilapia (Oreochromis niloticus), which is raised in the ISET fish station. Rosso in Mauritania. Fish has always been an abundant and inexhaustible food. And the reality is completely different, we are faced with the fact that many stocks of freshwater fish are poorly known. In this case we proposed to study the effect of the biotic factors on tilapia parasitism that will be the size, the sex of the fish with an analysis of the prevalence, the intensity and the abundance parasites. Among the parasites determined, we opted for the analysis of the dynamics of populations of those most represented within the parasitic communities of the fish examined, such as: Lernaea cyprinacea Linnaeus, 1758 copepods parasitic fish Tilapia.
bread. The sex of the fish was determined according to Shelton [2], they are transported to the laboratory to perform the parasitology examination.

Parasites research
In the laboratory, the fish are weighed, measured. Then, their different organs carefully removed and examined for parasites Figure 2. The gills were collected, placed in Petrie's boxes containing water and examined for parasites. The parasites were collected and preserved in 40% formula.

Study of parasites
We were interested in the morphology and biometry of parasites published in books and articles by comparing them with the parasites we observed Figure 3. This comparison concerns the external morphological characters of copepods such as antennas, antennules, head, thorax and abdomen [3,4].

Statistical Analyzes
The data was entered on Excel and analyzed by SPSS version 22.0. Infection levels were expressed as prevalence, mean intensity, and abundance as defined by Bush, Lafferty, Lotz, and Shostak (1997). An ANOVA was done to test the effect of height, sex and season on the rate of infestation. (Table 1) The results show a prevalence of 16.4% higher in males than females while the infested fish are more numerous in females (Figure 2,3 & Table 2)  The parasite indices that were revealed in the results of this study show that parasite infestation reached 14.1%. Figure (4-6).

Discussion
This parasite has been reported in Patagonia, a party of Argentina in common carp [5,6]. During this study, it was distributed over several areas of the body namely the mouth, skin and fins. The most severely infected areas were found near the base of the dorsal fins. The lessons found were similar in all fish. Parasitology revealed hyperplasia of the epithelium, abundant infiltration of inflammatory cells and fibrosis, not only in the epidermis, but also in the dermis and muscle tissue. This was confirmed by Plaul [7]. The infestation of fish with these copepods revealed that the number of parasites decreases with the size of the fish (p>0.05). On   This graph shows that males are month infested during this study as females and Lernaea cyprinacea population was higher in females.