EFFECT OF PH AND WATER TEMPERATURE ON THE DEVELOPMENT OF THE JAPANESE CRAYFISH, CAMBAROIDES JAPONICUS EGGS IN VITRO

摘要

We incubated the endangered Japanese crayfish (Cambaroides japonicus) eggs in vitro at the different water conditions, i.e., pH (from 3 to 12 using 20°C water) and water temperature (from 2 to 20°C using pH 7 water) in order to understand the suitable egg rearing conditions. Crayfish eggs sampled just after spawning (15 May, 2009) were not able to survive until hatch out. This result strongly suggested that early stage of eggs effectively develop when attached to the pleopods of the mother. In contrast, crayfish eggs that were before hatching (31 July, 2009) were able to survive in a wide range of water conditions. However, they were weak for acid condition. These findings suggested that acid conditions (i.e., acid rain) caused by human activities might be spurred the drastic decline of Japanese crayfish.