Observation of Correlation between Water Quality and Pulse Counts by Snapping Shrimps for Shallow Sea Environmental Monitoring

Snapping shrimps, which make peculiar pulse sounds, are found everywhere in the world. This research examined the validity of pulse counts of snapping shrimps as an indication of sea environmental conditions. Pulse counts can be gained without special biological knowledge merely by recording their sounds for a few minutes using a hydrophone. The pulses can be heard not only in Japan but also in other parts of the world. However, the pulse count varies by region and seems to decrease in places where the water quality is not very good. Especially, few pulse counts were obtained at areas where anoxia occurs in the summertime. We found from the Ministry of the Environment that the pulse count correlates with the water quality of sea areas. From field surveys and laboratory experiments, this method can be a useful index of the effect of water pollution on benthic animals. A fixed-point observation is very important because the pulse count shows regional variations.