Influence of salinity on the biology of the Neotropical cladoceran Moina eugeniae Olivier, 1954 (Branchiopoda: Moinidae)

Moina eugeniae Olivier, 1954 is a common cladoceran species in the zooplankton of saline lakes in central Argentina. Information on this species comes mainly from field studies, and there are few data on its tolerance to environmental factors that help explain its geographic distribution. The objective of this study was to examine the influence of salinity on its biology through bioassays. Treatments were carried out with 7, 17, and 27 g/L of salt. Offspring less than 24 h old were placed in 25 mL containers. Every 48 hours until death, the medium was renewed, the offspring were fed with Chlorella vulgaris and the moults were measured. The optimum salinity was 17 g/L, which resulted in the highest survival and number of moults (29 ± 2.9 days and 10 ± 0.9 moults), the greatest number of clutches and total offspring per female (8 ± 1.07 clutches and 135 ± 13.14 offspring), and the largest size (1.97 ± 0.13 mm). While the best performance was found with 17 g/L salinity, indicating the halophilic character of this species, the lowest values at 7 and 27 g/L indicate some stress. Thus, changes in the salinity of lakes due to climate change could negatively affect the current geographic distribution of M. eugeniae.