Protist plankton of Lake Khanka

We present data on studies of protists in Lake Khanka in late August-early September. A total of 99 species of protists have been found, of them 14 ph ytoflagellates, 14 zooflagellates, five sarcodins, two heliozoans, 62 infus oria, and two suctorians. Small infusoria from the class of Kinetophragmino phora, order Oligotrichida, as well as suborder Tetrahymenina were most num erous. The density of many protist species in Lake Khanka exceeds markedly that in several other high-productivity water reservoirs. Most of the proti sts belong to bacteriovores (bacteriophages). Many of the found species hav e high density. This is evidence of the production of bacterial plankton in the lake. In view of very high water turbidity in the lake, we assume that the total production of phytoplankton is not that high. In this connection , an abundance of protists (protist plankton) indicates is an indication fo r the existence of an additional source of organic matter in Lake Khanka.