抄録
Predation pressure of Noctiluca scintillans on diatoms and thecate dinoflagellates was investigated off the western coast of Kyushu, Japan by a comparison between the taxonomic composition of prey in the food vacuoles of N. scintillans and that in the ambient water. The ratios of total diatoms and centric diatoms in the food vacuoles were higher than those in the ambient water, while thecate dinoflagellates and pennate daitoms showed a reverse trend. These results indicate that predation pressure of N. scintillans on total diatoms is higher than on thecate dinoflagellates, and that the pressure on centric diatoms is stronger than that on pennate ones. Among the centric diatoms, Chaetoceros and Bacteriastrum were dominant in the food vacuoles and their respective ratios were higher than in the ambient water. Their chain-forming colonies with long setae appear to be easily trapped by N. scintillans tentacles and this is probably the cause of the high predation pressure of N. scintillans on centric diatoms.
