Larval Development and Salinity Response of Two Species of Fresh Water Shrimps Paratya compressa, P. improvisa, Living in Shizuoka Prefecture

Abstract

This study examined the larval development and salinity response of Two species of fresh water shrimps Paratya compressa and P. improvisa. With both kinds of shrimp, they progressed through the same 8 stages during the larval period. However, the larval period lasted 15 to 18 days in P. improvisa, while the P. compressa became larva in 26 to 38 days. The appendix appeared in P. improvisa earlier than P. compressa. All larvae of P. compressa died without molting, under non-feeding conditions and at 5 levels of salinity. None of the shrimp reached the 3rd zoeal stage except for those in 34 psu. Both kinds of shrimp lived longer in 8.5 and 17 psu than other levels of salinity. In 34 psu, P. improvisa lived 1 to 1.4 days while P. compressa lived 4.2 to 6.1 days. It has become clear that the two species have the larval development suitable for each living environment and have lost the viability in high salt water as P. improvisa has adapted to fresh water.