Localisation et caractérisation de la ressource naturelle Artemia dans les milieux salins algériens. (Zones Humides de l’Ouest, de l’Est et Sahariennes)

Abstract

The brine shrimp Artemia is an Anostracan branchiopod crustacean occurring worldwide in hypersaline lakes, ponds and lagoons, as well as in man-operated solar salt works. In addition to its unique osmoregulatory capacity, brine shrimp is adapted to this harsh environment by the capacity to produce diapausing cysts, dormant embryos enveloped in a chorion, when the conditions turn unfavorable. The emerging instar I nauplius is a convenient substitute for the natural plankton diet of fish and shrimp larvae. The first part of our study summarizes the results of a study on the location and morphological characterization of Artemia populations present in different hypersaline environments in Algeria (types and sebkha Chott). Sebkhas and Chotts are two types of closed basins of inland waters. A multivariate discriminate analysis, applied to morphometric parameters obtained from adult individuals reared under standardized conditions, allowed to differentiate species and strains. The second part quantifies the effect of temperature on the variables of the life cycle of Artemia populations in Algeria under standard conditions. The third component study highlights the effect of competition between indigenous Algerian in a mesocosm during spring. The wine is in a medium composed of brine 65 gl-1 and a mixture of microalgae (Dunaliella sp and Tetraselmis sp). A number of 100 nauplii, aged from 48 hours of hatching cysts pure populations composed of: A. salina, A. parthenogenetica diploid and tetraploid, are introduced into this environment. Seasonal variations cause changes in the competitive abilities of the three indigenous forms used. The fourth study focused on biometrics of cysts of various Algerian populations, collected in the wild and laboratory products. Parallel biometrics freshly hatched nauplii of sexual and parthenogenetic populations is highlighted, and some hatching parameters. The profile analysis of biometric cysts is similar to that of Mediterranean countries. It consists of three groups: the cysts produced by sexual populations with a small diameter, those of the tetraploid parthenogenetic females with a larger diameter and last cysts of parthenogenetic diploids with an average diameter between the two previous groups. The dimensions of the nauplii of various Algerian populations are in the size range that allows predicting that these nauplii can be used in aquaculture. In the study of hatching parameters, Algerian populations appear to have acceptable yields, which resemble common commercial cysts. They can be used in the aquaculture industry. The last part study the profile of fatty acid of some Algerian cysts populations. The fatty acid composition will allow to know the nutritional value of these populations from different origins and will subsequently compared to that of commercial species to determine its possible use in aquaculture. Analysis of the fatty acid content of Artemia cysts from Algeria reveals variability between different populations and within the same population from one period to another. Bethioua population meets the criteria of marine type. Populations of Adrar and Melghir are of fresh water type. The group of population from El Golea, Ezzamoule and Rélizane has a fatty acid profile mixed, rich in eicosapentaénoic acid and linolénic acid. The nutritional value of Algerian populations of Artemia is comparable to the commercial species (A. franciscana). The only variable is the composition of linolénic acid which is high in the American species, and the eicosapentaénoic acid is dominant in the Algerian populations. The Algerian populations may be of use in aquaculture.