Abstract
In summer of 2013, occurrence of kelp (saccharinian species) was surveyed by scuba diving at five sites on the coast of southern Sakhalin (Yablochnyy, Bogdanovitch, Krilion, Korsakov and Lesnoye), Russia, and one site on the coast of northern Hokkaido (Wakkanai), Japan. Satellite-images of surface water temperature along the coast of these sites were analyzed to perceive the relationship between water temperature and occurrence of kelp. Satellite images indicated that water temperature at the sites of the Sea of Japan (Yablochnyy, Bogdanovitch and Wakkanai) was higher and highest at Wakkanai. The site of Okhotsk Sea (Lesnoye) was the coldest, and the site of Aniwa Bay (Korsakov) showed temperatures intermediate between the Sea of Japan and Okhotsk sites. In general, the kelp Saccharina japonica var. ochotensis was dominant among saccharinian algae and its occurrence depended on water temperature of the surveyed sites. At Wakkanai, S. japonica var. ochotensis was scarce whereas the highest standing crop and density was observed at Korsakov, the second coldest site among the all sites. Only at Wakkanai, the sea urchin Mesocentrotus nudus appeared and the population of S. japonica var. ochotensis was composed only of first-year sporophytes. Species diversity of kelp was highest but S. japonica var. ochotensis has never been found at Lesnoye. Occurrence, standing crop, density and species diversity of saccharinian algae were considered to be affected by the water temperature.
