Biochemical composition and digestive enzyme activity during naupliar development of Artemia spp from three solar saltworks in Greece

Three parthenogenetic brine shrimp Artemia populations from saltworks in Greece (Messolongi, Milos and Polychnitos) were studied with regard to their biochemical composition and the activity of digestive enzymes in four developmental stages from decapsulated cysts to nauplii instar III. The content of protein and RΝΑ was highest in nauplii instar II (65.10 and 6.23% dry weight, respectively), while that of total lipid was highest in nauplii instar I (11.40% dw). The carbohydrate content was highest in decapsulated cysts (10.30% dw) and about one half that value in nauplii instar I. The DNA content was ten-fold higher in nauplii instar I than in decapsulated cysts with the highest levels in nauplii instar III (3.67% dw). The activity of alkaline phosphatase, leucine aminopeptidase, valine aminopeptidase, cystine aminopeptidase, β-galactosidase, β-glucosidase, esterase lipase (C8), esterase (C4), N-acetyl-β-glucosaminidase, α-fucosidase, acid phosphatase and naphthol-AS-BI-phosphohydrolase increased significantly from decapsulated cysts to nauplii instar II and remained constant or decreased in nauplii instar III. In nauplii instar II, leucine aminopeptidase, β-galactosidase, alkaline phosphatase and esterase (C4) demonstrated higher activity levels (140.90, 133.62, 66.01 and 45.47 nmoles/100 µg dw within 5 min, respectively) of the aforementioned enzymes. The Artemia population of Messolongi had significantly higher levels of DNA, protein and alkaline phosphatase activity per individual, as well as body weight, compared to the Artemia populations of Milos and Polychnitos. The latter population showed the lowest level of lipid and the highest esterase activity (C4) per individual. There was a reverse relationship between the protein content and leucine aminopeptidase activity, lipid content and esterase (C4) activity, carbohydrate content and β-galactosidase activity among the three Artemia populations. The variations observed in the biochemical composition and the activity of some specific enzymes should be taken into consideration in selecting these Artemia populations from Greece for application in aquaculture.