Can salinity changes affect reproductive success in the brown shrimp Crangon crangon?

In coastal environments, salinity variations may affect phases in crustacea n reproductive cycle. Brown shrimp Crangon crangon Linnaeus, 1758 (Decapoda ) are known to undertake breeding migrations between the sea and coastal wa ters (lagoons, estuaries). After a major flooding, the salinity of the Vacc ares coastal lagoon (Rhone River delta, France) dropped from 15 parts per t housand to 5 parts per thousand in a few days and remained low during follo wing years. The aim of this study was to assess the impact on this environm ental change on the reproduction of brown shrimp. We first tested whether f emales C. crangon had the ability to become ovigerous at a salinity as low as 5 parts per thousand. Furthermore, the question whether salinity had an impact on fecundity was addressed. Experiments in aquaria were carried out for 180 days in the laboratory, with three replicates at three salinities ( 5, 15, and 25 parts per thousand respectively), keeping local photoperiod a nd temperature. Mortality was significantly higher in tanks at 5 parts per thousand than in those at higher salinities. Females reared at 25 parts per thousand salinity started to become ovigerous after 32 days; at 15 parts p er thousand ovigerous females were only recorded after 80 days. No female b ecame ovigerous at 5 parts per thousand. A brackish salinity (15 parts per thousand) would delay ovarian development in C crangon, whereas a low salin ity (5 parts per thousand) seemed to inhibit maturation. Fecundity was high er in females reared at 25 parts per thousand than in those reared at 15 pa rts per thousand. Results are explained and discussed taking into account e ventual trade-off between reproduction and maintenance activities. Experime ntal data suggest that a too-low salinity in brackish lagoons may affect re productive success of migratory natant decapods, such as C. crangon.