鶴岡市公園3池(山形県)における植物プランクトンの季節的消長と黄金色藻の優位性

抄録

Seasonal changes of phytoplankton were studied with special reference to the Chrysophyceae in three ponds at Tsuruoka Park, Tsuruoka, Yamagata Prefecture from September in 1961 to September in 1962.
190 species, 15 varieties, and 2 forms of phytoplankton and 63 species and 9 varieties of zooplankton were recorded throughout the study period. 78 taxa of the Chlorococcales, 38 of the Chrysophyceae, and 37 of the Euglenophyceae formed 37.7%, 18.4%, and 17.9% of total number of phytoplankton species, respectively.
The highest density of total phytoplankter cells in each pond was found in August in Pond No. 1 (43, 000 cells/ml) and Pond No. 2 (90, 000 cells/ml), and in May in Pond No. 3 (19, 000 cells/ml). The lowest desity was recorded in February in Pond No. 2, and in March in Ponds Nos. 1 and 3 (300-400 cells/ml). The Chlorococcales occured abundantly throughout the years studied. The Cyanophyceae dominanted in summer, the Chrysophyceae in winter. A large number of the Volvocales, the Bacillariophyceae, and the Euglenophyceae were found at a few samplings.
The highest densities of phytoplankton cells, especially of the Chrysophyceae were found in winter when the temperature and pH values of pond waters were the lowest throughout the year. 3, 000 cells/ml in Pond No. 3 on February 6, 1962 was the highest value among three ponds, and occupied 78% of total phytoplankters in the pond.