SEASONAL VARIATION IN FREQUENCY OF DIVIDING CELLS OF FRESHWATER PHYTOPLANKTERS

摘要

The frequency of dividing cells (FDC) of a natural phytoplankton community was studied seasonally in a freshwater pond to which water directly from Lake Kasumigaura was supplied. Phytoplankton samples were collected every 3 h at three depths (5, 30 and 75 cm) over 24 h periods in each of the four seasons and examined for FDC, cell size and abundance. Dominant phytoplankton species were Synedra ulna, Cyclotella kutzingiana, Chlamydomonas cingulata and Oscillatoria tenuis With Melosira italica, Cryptomonas ovata, and Synechococcus sp. Being seasonally abundant.