Diel vertical migration of Daphnia in Lake Kizaki : Difference in its pattern depending on the daphnid's body size

概要

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The pattern of diel vertical migration (DVM) of Daphnia galeata was analyzed in summer in Lake Kizaki (a small mesotrophic lake) with maximum depth of 29.5 m. Juveniles, small adults and medium-sized adults stayed the whole day at 4-8, 8 and 14 m depths, respectively, and did not perform DVM, while large adults showed DVM between 14 m and near the bottom layer (26-27.5 m). Smaller adults had larger clutch sizes relative to their body size and allocated more energy to reproduction than larger adults. They might have compensated for loss due to predation by producing abundant offspring in the epilimnion where the food level was higher. On the other hand, the larger adults performed DVM to reduce mortality due to predation at the cost of reduced reproductivity induced by environmental factors in the hypolimnion (low concentrations of food and oxygen). The study thus demonstrated that even a single population of Daphnia can show different DVM patterns depending on body size (life stage).
信州大学の論文