Abstract

This study analyzed the movement distance and locomotion speed to understand the mobility of Unionidae (Anodonta woodiana, Unio douglasiae). In the sand area of the Nakdong River, the average movement distance was measured to be 296.5 cm for the A. woodiana and 395.1 cm for the U. douglasiae. In the mud area, the average movement distance for the A. woodiana was 257.0 cm, U. douglasiae was 254.7 cm. Both species moved a long distance in the sand area. In a lab tank, the average locomotion speed of A. woodiana was 39.1 cm/hr. In the sand area of the Nakdong River, the average locomotion speed for the A. woodiana was 61.1 cm/hr, U. douglasiae was 122.7 cm/hr. In the mud area, the average locomotion speed for the A. woodiana was 69.1 cm/hr, U. douglasiae was 67.8 cm/hr. The results showed that the locomotion speed of U. douglasiae was faster than that of A. woodiana. The analysis of the correlation between size and locomotion speed showed that the Spearman's rank was positive in both sand and mud areas. The analysis showed no significant difference between individual size and locomotion speed (P > 0.05), which means that larger individuals tend to have a faster locomotion speed. Based on the study's findings, it is believed that controlling the discharge amount and rate of dams, lakes, and weirs could help secure the survival stability of freshwater mollusks.