L’ichtyofaune de l’Oued Righ: Biologie et dynamique de l’Acara Rouge Hemichromis bimaculatus (Gill, 1862) et de l’Aphanius de Corse Aphanius fasciatus (Nardo, 1827)
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Date
2015
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Abstract
This study is devoted to the study of the ichtyodiversity of the region of Oued
Righ (Southeastern Algerian), the biology and the dynamics of two species
Hemichromis bimaculatus (Gill, 1862) and Aphanius fasciatus (Nardo, 1827). It
comprises three parts.
The first part describes the general characteristics of the study area: the
geography, the geology, the hydrology and the climatology. In addition, the study
area, the methods and the sampling techniques were described.
The second part is a contribution to the knowledge of the ichtyofauna of the
inland waters of the region of the Oued Righ, the ecology of the species and their
distribution. The inventory carried out in 3 ecosystems of this area (channel of the
Oued Righ, lake Ayata and lake Temacine), between December 2010 and December
2011, allow us to count 4 species (Hemichromis bimaculatus, Tilapia zilli, Aphanius
fasciatus and Gambusia halbrooki) belonging to 3 families (Cyprinodontidae,
Poecilidae and Cichlidae). The demographic structure and the dynamics of the
populations of the 4 species are analyzed by site. The results show a similarity of the
temporal distributions and the frequencies of the sizes between the various sites
considered.
The third part shows a thorough study of the biology of two species;
Hemichromis bimaculatus (Gill, 1862) and Aphanius fasciatus (Nardo, 1827). The
samples were carried out between December 2010 and December 2011. The
determination of the type of allometry reveals mainly a negative growth for the two
species. Scale marginal growth allows identifying only one growth stop annulus per
year for both species. Occurring in April for H.bimaculatus and in May for A.
fasciatus. The growth of the two species has been described by the classical model
of Von Bertalanffy. The performance index (φ) shows a relatively weak growth of
the local population of A. fasciatus. The relative growth of the two species is globally
negative, (b = 2.8) for H.bimaculatus and (b = 2.86) for A. fasciatus. Longevity is
approximately 3 years for H. bimaculatus and 6 years for A. fasciatus. The sex-ratio is
clearly in favour of the females for both species. Macroscopic examination of gonads
and gonado-somatic index indicated that spawning occurs once a year between
February and July for the two species. The length at the first maturity for H.
bimaculatus is 4cm for males and 5.5 cm for females. On the other hand and for A.
fasciatus is 4.5 cm for males and 5 cm for females.