Ecological constraints, dynamics of the size-age structure and sexual structure of the population, and characteristics of reproduction and life history traits of the stigophilic amphipods were investigated in the flooded forest Crni jarki near Đurđevac. The triplicate samples of crustaceans were collected seasonally for one year in three distinct aquatic microhabitats (flowing xylal with argylal, standing xylal with argylal and flowing phytal) using a benthos net (diameter 21 cm, and 500 µm mesh size) during the periods of elevated aquifer levels (March, April, May, and December). The majority of amphipods were collected in flowing xylal with argylal. The eudominant amphipod species (> 73 %) in all microhabitats was Synurella ambulans, while the Niphargus valachicus was subrecedent species (< 8 %). The percentage of females reached its peak (100 %) at the end of breeding season in flowing phytal, while the percentage of males peaked (70 %) at the beggining of breeding season in standing xylal with argylal. Juveniles were prevailed during the spring at the end of the breeding season in May, while adult specimens were disappeared from the population in the same month. During the study, live ovigerous females of Synurella ambulans were sampled in order to determine correlation coefficients of the number of eggs with the body length and body mass. Fecundity was positively correlated with body size and negatively correlated with body mass. The egg counts ranged from 11 to 38. The wetland population of Synurella appears to have a one-year life cycle.