2023 年 52 巻 p. 1-13
We examined the survival and moulting of starved early-stage-zoeae of atyid shrimps—amphidromous Paratya compressa and landlocked Paratya improvisa—under different salinity and temperature conditions to attain a better understanding of larval adaptation to freshwater environments in landlocked shrimp. The first stage zoeae were cultured without foods under 25 combinations of different salinity (0, 8.5, 17, 25.5, and 34 ppt) and temperature (20, 23, 26, 29, and 32°C) levels. The larvae of P. compressa did not moult, whereas larvae of P. improvisa are lecithotrophy and moulted to the third stage zoeae at 0–25 ppt (and rarely to the fourth stage zoeae at 8.5–25 ppt). However, all larvae lost the ability to moult in open seawater conditions of 34 ppt salinity. The larval survival time was not largely different between these two species, even though the first stage zoeae of P. improvisa were much larger than those of P. compressa. The larvae of P. improvisa advanced the development shorter rather than surviving longer under starvation conditions. These findings suggest that the starvation tolerance, that is, lecithotrophic faster developmental rate of early stage zoeae of landlocked P. improvisa, adapted better to stay in or near parental habitats as well as to limited food conditions in freshwater environments.
