ミジンコによる浮遊性細菌の捕食〔英文〕

概要

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Feeding rates of three species of Daphnia on planktonic bacteria. either pure-cultured or in lake water were determined by measuring the changes in bacterial concentration (cell number) of the water. 1) Below the bacterial concentration of about 3×10^6/ml, the feeding rate was approximately proportional to bacterial concentration down to such a very low concentration as 40/ml. 2) For the lake water of Yuno-ko where the diatom, A sterionella formosa, was predominating, the feeding rate of D. longispina on bacteria was not affected by the presence of larger particulate matter like phytoplankton, if the initial concentration of bacteria was the same. 3) Pond water rich in the blue-green aiga, Microcystis aeruginosa, inhibited the feeding of Daphnia on bacteria, the reason being mainly attributed to the high pH of the water. 4) Comparison of four species of Daphnia revealed that both feeding and filtering rates increased with increasing body size. 5) Judging from the energy requirement (respiration) of Daphnia, it was suggested that planktonic bacteria in concentrations lower than 1×10^6/ml might play a rather minor role in the energy or carbon nutrition of Daphnia, even if the nutritional value of bacteria is assumed high. 6) An attempt to cultivate D. pulex with pure-cultured bacteria over several generations was unsuccessful.
1971-09-30