徳之島 4 河川の下流河口域における陸水産甲殻十脚類について 1． 各種の出現状況（鈴木廣志・政武文・元田浩三・林美樹・常加奈子・ 池村茂・永田映里奈・米山太平）
The surveys were conducted at the lower reaches of four rivers; Ohse R., Kametoku R., Shimoda R. and Minato R., in Tokunoshima Island to clarify the fresh- water crustacean decapod fauna in May and September 2020. A total of 2079 shrimps and crabs, divided into 20 species, 13 genus and seven families, was collected in the surveys. Among them seven species, i.e. Macro- brachium formosense, Caridina serratirostris, C. ty- pus, Ptychognathus ishii, P. barbatus, Eriocheir ja- ponicus and Deiratonotus japonicus, account for over 80 % of total number of individuals in each river. The species compositions of four rivers, however, were dif- ferent in each other. The differentiation was discussed considering the river environments.