Abstract
The island of Kunashiri is situated at the southernmost part of the Kurile Islands and is faced to the Shiretoko Peninsula by the Nemuro strait. The limnological surveys of the island were carried out by Viscount A. Tanaka and Prof. D. Miyadi and others during the summer of 1933 and 1934. The results of the explorations have already appeared in many papers chiefly in the Japanese Journal of Limnology, vol.3, 1934 and Internationale Revue der gesamten Hydrobiologie, vol.37, 1938. The materials of the present contribution were collected by Prof. D. Miyadi in the lakes of the island under consideration and their general aspects were reported by him from the limno-zoological standpoint, but the algae of those lakes are not reported as yet. The lakes of the island are divided chiefly into two parts geographically, one being situated at the side of the Nemuro strait (the Okhotsk Sea) and the other at the side of the Pacific. Most of them lie on the sea coast and are barried lakes formed by sand-dune.
There are some interesting species of phytoplankton in the lakes of the southwestern part of the island (south of 44° N. lat.). Staurastrum cingulum was the important constituent of the phytoplankton in the Lakes Tôhutu-ko and Nihon'iwaonneto, and Staurastrum dorsidentiferum var. ornatum was a remarkable planktont of Lake Tôhutu-ponto. These two species are not found as yet in large lakes of Hokkaido and the Tôhoku district except Lake Akan. These three lakes mentioned above and Lake Nikishoro-ko (all lie at the south of 44° n. latitude) are deeper among the lakes of Kunashiri and are fairly eutrophicated, showing a water-bloom by Anabaena flos-aquae, Microcystis aeruginosa, Coelosphaerium Kützingianum. Most of the small lakes in the northeastern part of the island are shallow in general, marshy-like, and are rich in desmids. The desmid-flora in the marshy lakes resembles that of Hokkaido, and not that of the island of Shinshiru. Only ten species are common to both the islands, 56 species of Kunashiri and 43 species of Shinshiru, but the survey of desmids in both the islands is not complete as yet. All the species of algae found each lake were listed in the present contribution.
