2024 年 53 巻 p. 113-119
Atyopsis spinipes is a freshwater shrimp species found in streams and rivers on tropical and subtropical Pacific islands. Juveniles of A. spinipes are also found in temperate regions of Japan, but adults are not, suggesting that juveniles do not successfully overwinter there. The present study investigated the low temperature tolerance of A. spinipes juveniles as a basis for predicting the northern limits of the species’ geographical range under global warming. Artificially raised juveniles were cultured in containers in which the temperature was adjusted to decrease from 20°C by 1°C every 48 h until all test juveniles had died. The survival rates of the juveniles largely declined below 16–17°C, and all died at around 12°C. The mean lethal temperature for juveniles was 14–15°C, which appears to be higher than winter temperatures in temperate regions and equivalent to those in the subtropical islands of Japan. A winter temperature of around 15°C may be the limit for successful overwintering by A. spinipes juveniles.
