Quantification of Effect of High Temperature on Survival Ability of the Juvenile of Manila Clam

Abstract

The ground temperature of the Wajiro tidal flat rises up to 40 °C in summer, and this high-temperature condition becomes one of the mortality factors of Manila clams. It was noted in a previous study that Manila clams die at 35 °C or higher, but there are few findings on the percentage of surviving individuals being related to the exposure time to a high-temperature condition. Hence, we carried out a high-temperature exposure experiment of clams, and formulated a survival rate as a function of temperature and exposure time. The formula derived from the experiment in the laboratory and the observation results of temperature and density of clams in the field was indicated the possibility that high-temperature condition was one of the survival factors of clams. It was considered to be valuable as a formula to quantitatively estimate the decrease in a clam population in relation to temperature and time.