Length-weight relationships of eight freshwater planktonic crustacean species in Japan

1. The relationships between body length and dry weight were examined for eight species of freshwater planktonic crustacea common in Japan: Eodiaptomus japonicus, Acanthodiaptomus pacificus, Daphnia galeata, D. similis, D. magna, Scapholeberis mucronata, Simocephalus exspinosus and Bosmina longirostris. 2. The relationships of two diaptomid species were similar and the approximate equation was lnW = 2.7 + 2.6*1nL, where L is prosome length (mm) and W is dry weight (μg). The carapace length-dry weight relationships in branchiopods were more variable, with the slope ranging from 1.9 to 2.9 and the intercept from 2.0 to 3.7. 3. The effects of food conditions on the relationship were examined in the laboratory, and the seasonal changes in the field were also studied. 4. Practical advice is presented for predicting crustacean weight from body length.