Aspects of the life span and phenology of the invasive freshwater shrimp Atyaephyra desmarestii (Millet, 1831) at the northeastern edge of its range (Upper Rhine)

Quantitative aspects of the life cycle of the freshwater shrimp Atyaephyra desmarestiiwere used to investigate its life span at the edge of its distribution area in Central Europe (Upper Rhine) for a period of three years. We estimated the proportion of the population surviving a second hibernation period. The appearance of ovigerous females in late spring was followed by a strong decline in the number of adults, the appearance of a high percentage of juveniles in late summer (0.58 ind./m 2), and their subsequent disappearance from the shore in winter. A small semivoltine cohort survived a second winter. The average life span was 12-15 (max. 29) months under laboratory conditions. In molecular studies (COX I), the Upper Rhine and Southern France populations clustered within the North Africa/West-Central Europe species clade. Due to its low productivity, this invasive species is unlikely to cause management problems.