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[Press Release] Evidence for ice-ocean albedo feedback in the Arctic Ocean shifting to a seasonal ice zone

Summer sea ice extent in the Arctic Ocean has been reduced by half in the last 40 years. This means that the Arctic Ocean is shifting from perennial to seasonal ice zone where the sea ice disappears in summer. Researchers have focused on several factors that cause this sea ice retreat. A research group that includes Prof. Kay I. Ohshima (Division of Earth System Science) provided quantitative evidence that ice-albedo feedback due to the albedo contrast between water and ice is a major factor in the sea ice retreat.

This research outcome is published in Scientific Reports.

Please visit links below to view the press release (Japanese ver. only).
Research Press Release (PDF)

[Press Release] Reduction in cloud condensation nuclei activity of water-soluble aerosols caused by biogenic emissions in a cool-temperate forest

Biogenic organic aerosols can affect cloud condensation nuclei properties. Researchers, however, are not yet sure of how the difference in the types of terrestrial biogenic sources and the abundance of organics relative to sulfate affect cloud condensation nuclei properties. A research group that includes Astrid Müller, a doctoral student, Assist. Prof. Yuzo Miyazaki (Division of Earth System Science), and Prof. Tsutomu Hiura (Division of Biosphere Science) have investigated water-soluble aerosols for two years in a cool-temperature forest at Tomakomai Experimental Forest, HU (northern Japan). They found evidence that a reduction in cloud condensation nuclei activity of water-soluble aerosols was caused by biogenic emissions from litter/soil microbial activity near the forest floor.

This research outcome is published in Scientific Reports.

Please visit links below to view the press release (Japanese ver. only).
Research Press Release (PDF)

[Press Release] Roots of Japanese house mice: implications for understanding the origin of Japanese

A research group of Prof. Hitoshi Suzuki (Division of Biosphere Science) have long investigated genetic diversity of Japanese house mice (Mus musculus) across Eurasia, including the Japanese archipelago, for over 30 years. Here, by using genetic analyses, his group revealed a long-standing question: when and how the ancient house mice immigrated into Japan. The results of the analyses indicated that the ancient wild populations of the mice immigrated at least twice into Japan in association with prehistoric developments in agricultural techniques by human beings: first from Southern China ca. 4000 years ago and then from the Korean Peninsula ca. 2000 years ago. These two lineages were mixed first in western Japan, then in northern Japan with a delay of about 1,000 years. Furthermore, the results also suggest that another lineage of South Asia-origin might have immigrated into Japan before the two lineage immigrations.

This research outcome is published in Biological Journal of the Linnean Society, a British biological journal.

Please visit links below to view the press release (Japanese ver. only).
Research Press Release (PDF)

[Press Release] Bryophytes as bioindicators of the atmospheric environment in urban-forest landscapes

Prof. Tsutom Hiura (Division of Biosphere Science; Tomakomai Experimental Forest) and Lecturer Yoshitaka Oishi (Fukui Prefectural University) developed an efficient method evaluating the atmospheric environment in urban-forest landscapes by using bryophytes. Bryophytes, which have simple body structures, can respond sensitively to environmental changes, particularly atmospheric environments. In this paper, they showed that measuring concentration and stable isotope ratio of nitrogen in bryophytes enable us to evaluate a level of nitrogen pollution, which is becoming serious in urban areas. In addition, they found that richness of hygrophilic life-forms can reflect the level of drought stress associated with urban heat islands. The combinational use of these bryophyte metrics can contribute to comprehensive understanding of atmospheric environments.

This research outcome is published in Landscape and Urban Planning.

Please visit links below to view the press release (Japanese ver. only).
Research Press Release (PDF)

Prof. Masashi Ohara and Assoc. Prof. Ken-ichi Yamazaki selected for Hokkaido University Commendation for Excellent Teaching

The Institute for the Advancement of Higher Education selects Hokkaido University Commendation for Excellent Teaching recipients every year based on students’ feedback on the General Education Courses.

Thirty-two courses were selected based on the students’ feedback conducted last year. Prof. Masahi Ohara and Assoc. Prof. Ken-ichi Yamazaki, Division of Biosphere Science, were selected as commendation recipients. Prof. Ohara has been selected for the commendation 5 years in a row!

Name of their lectures recognized:
General Education Courses “Biology II” (Prof. Ohara)
General Education Courses “Biology I” (Assoc. Prof. Yamazaki)

Please refer to the following URL for more details:
http://educate.academic.hokudai.ac.jp/center/enquete/enquete.htm

[Press Release] “Herring-derived nutrients”: evidence from historical delta15N records of kelps

Kelp (Saccharina spp.) beds along the west coast of Hokkaido (Japan Sea) were used to be commercially exploited, but are currently decreasing. This is believed to be due to the present nutrient limitations. To date, however, the mechanisms that caused the nutrient limitations are still unclear because of a lack of scientific data on historical nutrient changes in this region. Dr. Takanori Kuribayashi (he received a doctoral degree as an adult student of our school), Lecturer Tsuyoshi Abe (Hokkaido University Museum), and Specially-appointed Prof. Shigeru Montani (Division of Biosphere Science) hypothesized that nutrients for Saccharina spp. beds may have been derived from spawning herrings (Clupea pallasii), which were previously caught 500–1000 times more than now. To test this hypothesis, they focused on stable nitrogen isotope ratios (delta15N) of 100- to 135-year-old Saccharina specimens preserved at Hokkaido University Museum. Delta15N values of old Saccharina specimens in this region were in the range of 10‰, which is significantly higher than the current specimens (3–7‰). This high delta15N supports the “herring-derived nutrients” hypothesis.

This research outcome is published in PLOS ONE.

Please visit links below to view the press release (Japanese ver. only).
Research Press Release (PDF)

[Press Release] Greater than expected increase in atmospheric water vapor in response to increased air temperature

Extremely heavy precipitation affects human society and the natural environment, and thus its behavior under a warming climate needs to be elucidated. Assoc. Prof. Tomonori Sato (Section of Integrated Environmental Science) and Dr. Mikiko Fujita (Japan Agency for Marine-Earth Science and Technology) analyzed the relationship between atmospheric water vapor content and surface air temperature using precipitable water vapor derived from global positioning system satellites. This research outcome is published in Scientific Reports.

Please visit links below to view the press release (Japanese ver. only).
Research Press Release (PDF)

[Press Release] Prof. Sugiyama and Assist. Prof Hirano as members of 59th Antarctic Research Expedition!

It’s our school’s pleasure to inform you that Prof. Shin Sugiyama and Assist. Prof. Daisuke Hirano were chosen as members of 59th Japanese Antarctic Research Expedition.

Please visit the following webpage of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan for more details (Japanese ver. only).
Press Release (MEXT)

[Press Release] Improving detection accuracy of incoming Asian dust (Kosa)

Monitoring incoming particulate matters such as Asian dust (Kosa in Japanese) is essential to keep us healthy. On 7 March 2016, the Terra/MODIS true color image clearly captured a yellow band over Hokkaido, Japan. On the same day, however, the Japan Meteorological Agency reported no Kosa event in Japan. An international research team that includes Assist. Prof. Sumito Matoba (Division of Earth System Science) investigated whether this event was due to Kosa transport or not, with the ground-based observations in Sapporo and Takikawa, Hokkaido and NASA’s MERRA-2 re-analysis data. This research outcome is published in Scientific Online Letters on the Atmosphere (SOLA), a letter journal of the Meteorological Society of Japan.

Please visit links below to view the press release (Japanese ver. only).
Research Press Release (PDF)

[Press Release] Molecular phylogeny of a parasitic isopod family Cymothoidae

Parasitic isopods of the family Cymothoidae may be one of the most familiar fish parasites particularly to fishermen. Cymothoid isopods are distributed in diverse aquatic environments from freshwater to deep sea with various parasitic modes (fish mouth, gill, skin, and body cavity). Their evolutionary diversification process is, however, still largely unknown. Assist. Prof. Ryota Kawanishi (Section of Integrated Environmental Science) and his collaborators of Ehime University, Hirosaki University, and Research Institute for Humanity and Nature conducted molecular phylogenetic analyses by collecting cymothoids and related species from across the world. They found a possibility that a common ancestor of Cymothoidae originated from the deep sea and expanded to shallower habitats. They also revealed at least two independent origins of freshwater lineages in the family. This research outcome is published in Marine Biology.

Please visit links below to view the press release (Japanese ver. only).
Research Press Release (PDF)

Graduate School of Environmental Sceince, Hokkaido University