Impact of Paddy Field Water Management Practices on the Reproduction of Tokyo Daruma Pond Frog

Abstract

We investigated the impact of paddy field water management practices on the reproduction of the endangered Tokyo Daruma Pond Frog, Pelophylax porosus porosus, in the paddy waters of the plain-field region. The relationship between young frog and tadpole emergence and paddy field water management practices was investigated in field block units (2017, 2018) and in every paddy field (2019). Field block unit surveys showed that the population density of young frogs was lower when the midseason drainage period was longer and was higher when the midseason drainage period was shorter, in 2017 and 2018. In the paddy field survey, young frogs and tadpoles were not found in paddy fields where midseason drainage occurred, but were observed at several peaks in the paddy fields where midseason drainage did not occur, in 2019. This case study has demonstrated that midseason drainage negatively affected the reproduction of this species. Further analysis is required to determine the relationship between the emergence of young frogs and tadpoles and the water management practices of paddy fields.