Hatch and Die: The Effect of Salinity on the Performance of Moina macrocopa (Straus, 1820) (Cladocera: Moinidae) Populations Initiated by Post-Diapause Females

Freshwater salinization may have important implications for the abundance and diversity of
\nzooplankton, which play a key role in the functioning of aquatic ecosystems. Many of these animals
\nundergo developmental arrest in the embryonic stage, which allows them to survive harsh periods and
\ncope with seasonal unfavorable environmental conditions. We studied the effects of salinity in the
\nexperiments with individuals and populations of the cladoceran Moina macrocopa on the life history
\ntraits and population parameters important for cyclical development of animals: the hatching success
\nof resting eggs; the survival of hatchlings; individual performance of post- diapause females and
\nperformance of populations initiated by post- diapause females. We observed a decreasing sequence
\nof salinities critical for traits and parameters studied in this work: from 8 g L -1, critical for hatching
\nof resting eggs, to 1 g L-1, critical for the ability of a population initiated by post- diapause females to
\nproduce resting eggs. We conclude that the relatively low salinity (1 g L-1) that does not suppress the
\nhatching of resting eggs reduces the ecologically significant ability of the M. macrocopa populations
\nto replenish the bank of resting eggs. Thus, freshwater salinization, in the long term, will prevent the
\nre-establishment of M. macrocopa and most probably other freshwater cladoceran populations from
\nthe banks of resting eggs