Quality evaluation of Artemia urmiana Günther (Urmia Lake, Iran) with special emphasis on its particular cyst characteristics (International Study on Artemia LXIX)

Artemia urmiana cysts were collected from seven sites in Urmia Lake, Iran. Biometrical analysis revealed that the mean values for the untreated cysts ranged from 262.7 to 286.6 μm, decapsulated cysts from 258.6 to 273.9 μm, and the chorion thickness ranged from 1.2 to 9.3 μm. The cyst samples were tested for their buoyancy at salinities of 35, 50, 100, 150 and 200 g/l. Two cyst batches from Great Salt Lake (Artemia franciscana) were also tested as reference material. It was found that the majority of Urmia cysts (over 60%) sank after 72 h even at the salinity of 200 g/l, while, GSL cysts reached a much lower figure (less than 10%) after the same time period. Transmission electron microscopy studies of the Urmia cyst chorion revealed a thinner alveolar layer and a thicker fibrous layer in comparison with the respective layers of A. franciscana cysts. A. urmiana instar-I nauplii biometry was also performed (total naupliar length: 466.3–505 μm). Six reproductive and four life span characteristics were investigated at salinities of 35, 50, 100, 140 and 180 g/l in order to evaluate A. urmiana performance at different salinities. A. urmiana individuals showed a preference for high salinity, since high mortality was recorded at 35 and 50 g/l. No significant differences were found between the three highest salinities (100, 140 and 180 g/l) tested (P > 0.05), with the exception of offspring per brood, reproductive period, and total life span. The analysis of highly unsaturated fatty acid (HUFA) profile of instar-I nauplii hatched from collected cyst batches resulted in low levels of eicosapentaenoic acid (20:5n-3) and high levels of linolenic acid (18:3n-3) ranging from 1.8 to 7.2 and from 32.7 to 54.7 mg/g DW, respectively. Only traces of docosahexaenoic acid (22:6n-3) were found.