磯魚の科組成の日周変化

The reef fishes of Honmura Bay in Kuchierabu Island were observed for 3 days in October, using SCUBA. Family name and number of fishes were recorded along the transect lines at the following times: 0000-0030, 0500-0530, 0530-0600, 0615-0645, 1200-1230,1650-1720, 1720-1750, and 1820-1850.

During the observation period the fishes of 25 families were observed. The fish community at study reef changed remarkably in families and number of specimens between day and night. According to the values of similarity index, CII, a high similarity was recognized in family compositions of the fishes observed at day times: 0615-0645, 1200-1230, 1650-1720, and 1720-1750, and at night times: 0000-0030, 0500-0530, and 1820-1850, respectively. The fishes observed at the time of 0530-0600, twilight time, were similar in family composition to those observed at the time of 1720-1750, but not to the others. The family composition of the fishes at study reef was considered to be nearly constant in the day time, and in the night time except for that between day and night. The fishes at study reef increased rapidly in number of specimens from morning twilight to dawn, and at noon. They decreased in the evening, rapidly at dusk, and before morning twilight.