Standing crop of second-year sporophytes of the Rishiri-Konbu kelp Saccharina japonica var. ochotensis was monitored by a diving survey in the coast of Tsugaru, Rebun Island, northern Hokkaido Japan, Sea of Japan from 1983 to 2018. Relationship between published data of the coastal surface water temperature of northern Hokkaido and the standing crop was analyzed. A significant correlation of the standing crop and mean water temperature of April, May, and June of one year prior of the survey was found. There is a significant correlation between the standing crop and published data of the catch volume of S. j. var. ochotensis in Rebun Island, and also in the Soya Region of northern Hokkaido. Monthly mean water temperature of May and June has been increasing from 1983 to 2018. This suggests that lower water temperature in spring and early summer leads to higher kelp resources in next year.

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Effect of temperature and water motion for growth of young sporophyte of Saccharina japonica var. ochotensis and S. cichorioides were compared under laboratory culture condition. The growth of S. japonica var. ochotensis was faster in 8℃ and 12℃ than in 4℃ whereas the growth of S. cichorioides was faster in 4℃ than in 8℃ and 12℃. Water motion also caused improvement of increasing efficiency of sporophyte area in S. japonica var. ochotensis. However, growth of S. cichorioides was not affected by water motion. These results suggest that affection of water temperature and water motion for growth of S. japonica var. ochotensis and S. cichorioides are different.

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Six species of two echinasterid genera were collected by snorkeling surveys from shallow depths (0–10 m) of Rishiri Island, Hokkaido, Japan: Henricia densispina, Henricia nipponica, Henricia reticulata, Odontohenricia occasus, and two undescribed species of Henricia. All these species were newly reported from Rishiri Island. We suggested the possibility that H. djakonovi is a junior synonym of H. densispina. These species were clearly discriminated by body color, and characteristics of pseudopaxillae, marginal plates, and abactinal, adambulacral, and oral spines. A key to species of Echinasteridae occurring in Rishiri Island is provided.

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From March 2022 to March 2023, bird observations were made in the Shosanbetsu village (N44˚30', E141˚50'), north-western Hokkaido. A total of 158 bird species including 87 species of Non-passeriformes and 71 species of Passeriformes were recorded.

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We reconstructed the vegetation history in and around the Minamihama Mire in a maar on Rishiri Island, northern Hokkaido dating back to ca. 5,500 cal BP. This reconstruction is based on the analysis of plant remains and pollen from three core samples taken from different parts of the mire, including both the margin and the central areas. After volcanic eruptions ceased, wetland vegetation started to grow around 5,500 cal BP in the maar. Ombrotrophic bogs, dominated by Sphagnum moss, began to form around 4,100 years ago in the central part of the maar. However, minerotrophic bogs persisted along the margin of the mire until about 220 cal BP due to the inflow of surface water from the maar slope. Picea glehnii forest started spreading into the wetland around 1,340 cal BP possibly due to a decrease in the moisture level on the bog’s surface. The lowland forests on Rishiri Island, including the maar slope, were a mixed coniferous and broadleaved forest dominated by deciduous Quercus until around 3,100 cal BP since the middle Holocene climate optimum. The Late Holocene climate deterioration led to a shift in the dominant tree species within the forests, with conifers such as Abies sachalinensis and Picea becoming prevalent. The forest on the maar wall was eliminated before ca. 80 cal BP and has since transitioned to the current bamboo community.

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A female Pennisetia fixseni admirabilis and two Synanthedon formicaeformis males were found on Rebun Island, Hokkaido, Japan. The female was probably depositing her eggs on leaves of Rubus idaeus L. subsp. melanolasius (Rosaceae), judging from her behavior. The two males were visiting flowering inflorescences of Angelica ursina (Apiaceae) and Eupatorium glehnii (Asteraceae), respectively, to ingest nectar.

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The carabid species Cymindis nigrifemoris Habu & Inouye, 1963 is reported from Rishiri Island, Northern Hokkaido, Northern Japan. Adititionaly, its barcode region (cytochrome c oxidase I: COI, COX1) was determined and deposited in GenBank (accession number: LC785707, deposited as C. daimio due to the taxonomic system of GenBank). The specimen will be deposited in the Rishiri Town Museum (RTMCl31).

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A Chiffchaff, Phylloscopus collybita, and a Pallas’s Grasshopper Warbler, Locustella certhiola, were observed at Numaura, southern Rishiri Island on May 5th, 2023. The former is newly recorded from this island, and the latter is the second observation since 1965.

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The objective of this research is to compile soil temperature data of surface soils (5 cm depth) for 11 years from 2001 to 2011, and to find new knowledge about soil temperature of Mt. Rishiri. Six points at different altitudes were selected as research sites, ranging from 25 m above sea level at the foot of Mt. Rishiri to 1410 m above sea level near the summit. Data logger type thermometers were buried at the depth of 5 cm in the soils in 6 sites, and soil temperature was measured once every hour. From these data, we calculated analytical values such as the daily average soil temperature, the monthly average soil temperature, and the daily range. The most distinctive feature was that at low altitude sites, the insulation and heat retention effect of snowfall worked in the winter, and the daily and monthly average soil temperatures remained stable around 0 °C. On the other hand, at high altitude sites, the number of days with average daily soil temperature below 0 °C exceeded 50%. It was found that the soils at these two locations were frozen for more than half of the year. In addition, the reference temperature was set to 0 °C, 5 °C, 10 °C, and 15 °C, and the effective cumulative temperature, which was the cumulative value of the time and temperature exceeding each temperature, was calculated, and the rate of change with respect to altitude was calculated depending on the difference in the standard temperature. I confirmed that there is a big difference.

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Dwarf bamboo species (Sasa spp.) were widely distributed in Hokkaido including Rishiri Island. They were known to flower simultaneously at intervals of several decade. We investigated their flowering and death of the dwarf bamboo Sasa spp. on roadside of Rishiri Island by visual observation. They flowered simultaneously in southwest area except for some area in Senhoshi.

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Fisherman’s short knife sheath, what is called “Koshi-Makiri”, has been used as a useful tool in Rishiri Island. Occasionally migrant fishermen at the golden age of herring fishing engraved their wooden sheath of Makiri knife with various designs and/or characters as a good omen. There was no chance to preserve these “Koshi-Makiri” specimens on this island because most of the migrant fishermen take their own artifacts to their hometown and the “Koshi-Makiri” knife itself is just a consumable supply. This report gives a detailed description of the only “Koshi-Makiri” specimen preserved in the Rishiri Town Museum with additional note for the three new specimens donated to the museum in 2023 by one of the authors, Chiharu Tobe. These three “Koshi-Makiri” knives were formerly belonged to the Tsumanuma collection.

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Rishiri Island is located off the northwest coast of Hokkaido. So far, no comprehensive list of coleopteran fauna has been published for the island, though many coleopterists have conducted field research there. I have conducted a literature survey to compile records with field research from 2019 to 2022 in order to assess the coleopteran biodiversity of the island. 534 species in 57 families from Dytiscidae through Brachyceridae are included in the first volume of the catalogue.

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