An Annual Variations Survey on the Distribution of Egg Clutches of Tohoku Salamander (Hynobius lichenatus) in the Tsunami Inundated Lowland Area of Moune, Kesennuma, Miyagi

Abstract

This survey monitored the quantity and distribution of egg clutches of Tohoku salamander (Hynobius lichenatus) in the tsunami inundated lowland area from the period 2012 to 2015, looking at the case of Moune district, Kesennuma city, Miyagi prefecture, Japan. After the 2011 Tohoku Earthquake, lowland area almost changed into wetlands by erosion and land subsidence, and seawater ran into a part of the lowland. Lots of egg clutches were found in the whole area in 2012. However several egg clutches deposited in brackish-water were dead. After 2013, the number of egg clutches declined, and the distribution moved inland. The number of egg clutches roughly increased in 2015, indicating the meta-population of Tohoku salamander’s resilience against temporary disturbance caused by the tsunami. Models of relations analyzed between the numbers of egg clutches in each year showed larger population had higher resilience and the numbers of dead egg clutches had negative correlation to the total numbers of egg clutches in late years. Results indicated that the environmental changes after the tsunami had more severe impacts on the population’s survival. However the population of Tohoku salamander had resilience under the natural state. This resilience may be weakened by man-made induced environmental changes and habitat loss from the tsunami recovery and reconstruction works. Hence, the need for conservation and monitoring was suggested.