International study on <i>Artemia</i>: 56. Characterization of two <i>Artemia</i> populations from Namibia and Madagascar: cytogenetics, biometry, hatching characteristics and fatty acid profiles

Two parthenogenetic Artemia populations from southern Africa, one from Swakopmund (Namibia) and another from Ankiembe saltworks (Madagascar) have been studied. The population of Namibia is mainly diploid (2n=42) with few tetraploid individuals (4n=84), while the one from Madagascar was found to be triploid (3n=63). No chromocenters have been observed in either of the two populations. The Namibian population has smaller cysts and nauplii compared to those of the Madagascar population. Discriminant analysis revealed significant differences in the biometry of the adults from the two populations. The two populations exhibited very good hatching characteristics. The study of fatty acid methyl esters revealed that the Namibian population belongs to the 'fresh water' type of Artemia showing low levels of eicosapentaenoic acid, whereas the population from Madagascar displayed exceptionally high levels of eicosapentaenoic acid, belonging to the 'marine water' type