Cyst size variability in invasive American Artemia franciscana Kellogg, 1906 (Branchiopoda, Anostraca) in Asia: a commercial approach

Abstract

Abstract Artemia is the most common live food that is used in aquaculture worldwide. This study reports on biometrical variation in the cysts of the introduced, originally American Artemia franciscana from 24 non-native localities and two native habitats, in Asia and the U.S.A., respectively. The results show, that the largest diameter of untreated cysts, the largest diameter of decapsulated cysts, and a thicker chorion usually are found in invasive populations. Because of the small cysts, which have an effect on an increasing quantity per unit weight and thus could be the cause of increased hatching efficiency, commercial productions of A. franciscana cysts from native sources should potentially be considered higher quality than productions from non-indigenous environments. Principal Component Analysis revealed that all cyst batches from San Francisco Bay were classified in one group and most of the invasive populations could be arranged in another, separate group. Although the diameter of the decapsulated cyst and chorion thickness showed a negative and significant correlation among invasive populations, there was no significant relationship within native populations. These observations contrast with biometrical patterns of parthenogenetic populations.