[Nagano University Press Release]: Effects of neonicotinoid pesticides on river microbial communities
IFB
2025-04-01 We are pleased to announce that a new scientific article authored by researchers at the Institute of Freshwater Biology has recently been published in Aquatic Toxicology, a leading international journal in its field https://www.sciencedirect.com/journal/aquatic-toxicology.
Key points of the study
The effect of the pesticide dinotefuran on freshwater biofilms (microbial communities) was measured for the first time using the EcoPlates method
Contrary to expectations, exposure to pesticides increased the metabolic activity of freshwater biofilms (microbial communities) on average
Among these, the metabolic activity of putrescine increased most significantly
Research Summary
The study advances knowledge of the effects of a common neonicotinoid pesticide, dinotefuran, on freshwater organisms using the EcoPlate method for the first time. In particular, the microorganisms living on the rocks of the river beds were studied to observe the disturbance induced by the presence of dinotefuran. We studied changes in metabolism as an indicator of stress in microorganisms. The results show that dinotefuran increased the mean catabolic activity of the freshwater biofilm. We also found that the catabolism of putrescine increased significantly after exposure to dinotefuran. Overall, we suggest that dinotefuran, at the concentration tested, has stressed the microorganisms. However, further research should continue to elucidate the complex response.
This research is part of a larger project investigating the effects of anthropogenic disturbances on river health, funded by the Japanese Ministry of Land, Transport and Tourism.
We conducted a satellite tagging survey of Japanese eels on Hachijojima Island!
IFB
On February 20-23, 2025, we conducted a spawning migration survey using satellite-based pop-up tags on farmed eels on Hachijojima. This is a new initiative in which farmed Japanese eels are transported to Hachijojima and released in coastal areas. Several dozen wild eels have been released along the coast of Japan so far, but there is still room for improvement in the satellite tags, and only a limited number of them have been able to cross the Kuroshio Current, a strong ocean current, and travel south. It is known that wild eels also live on Hachijojima, about 300 km south of Tokyo Bay, but since the Kuroshio Current is often farther north than Hachijojima, it is thought that if the migration starts from Hachijojima, we will be more likely to observe the migration behavior to spawning grounds far off the coast of Guam. This time we released two eels at Hachijojima.
This research is conducted as a supplementary research project of the International Eel Resources Unit of the Fisheries Agency, led by the Institute of Freshwater Biology of Nagano University, in cooperation with the Atmosphere and Ocean Research Institute of the University of Tokyo, Kyushu University, Shinshu University, Miyazaki Prefecture, Kumamoto Prefecture, and the Fisheries Research Institute. We would like to thank the Hachijo Office of the Island Agriculture, Forestry and Fisheries Research Center for their cooperation in this survey.
The year-end report meeting of the Chikuma River and Shinano River Research Group was held in FY2024!
IFB
On Thursday, February 13, 2025, the results report meeting of the River Erosion Control Technology Research and Development and River Ecology General Research Group of the Ministry of Land, Infrastructure, Transport and Tourism (Principal Investigator: Professor Hiroshi Hakoyama) was held online, and the Institute of Freshwater Biology of Nagano University, the Nagano Prefectural Fisheries Experimental Station, and Shinshu University reported this year’s research results to the Chikuma River and Shinano River River Office.
This research group, a collaboration between the Institute of Freshwater Biology of Nagano University, Shinshu University and the Nagano Prefectural Fisheries Experimental Station, is working on the Ministry of Land, Infrastructure, Transport and Tourism research project “The Importance of Habitat Continuity in Rivers - Impact Assessment and Conservation Measures for River Ecosystems” (Principal Investigator: Hiroshi Hakoyama), and there was lively discussion at each research presentation. This is the third year of the five-year general research, and the ultimate goal is for the research results to contribute to the river basin flood control in the Chikuma and Shinano Rivers, which is being carried out by the River Office.
Meeting Agenda
Opening remarks: Deputy Director Chikuma River Office
Introduction: Hiroshi Hakoyama (IFB)
Sakie Kodama (IFB): Distribution survey of two striped loach species
Leanne Faulks (IFB): Fragmentation of local waterways affects freshwater fish biodiversity
Alessandra Cera (IFB): Effects of water flow velocity on the metabolic functionality of freshwater epilithic biofilms: a field and laboratory study
Hiroshi Hakoyama (IFB): Towards modeling fragmented river systems
Ueshima Tsuyoshi, Shinkai Takamasa and Tashiro Seiya* (Nagano Prefectural Fisheries Experiment Station): Decrease in CPUE of smallmouth bass after typhoon disturbance in Chikuma River; Investigation of distribution of brown trout in Chikuma River by species-specific environmental DNA analysis and identification of river crossing structures that prevent distribution expansion
Masashi Toyoda (Faculty of Engineering, Shinshu University): River channel evolution in the middle reaches of the Shinano River, focusing on sediment dynamics within the river channel and changes in channel morphology
Shoichiro Iio (Faculty of Engineering, Shinshu University): Development of fish migration monitoring technology
Annual Eel Unit Report Meeting held at the Fisheries Agency
IFB
On January 28, 2025, the Annual Eel Unit Report Meeting for FY2024 was held at the Fish Agency in Kasumigaseki, Tokyo. This research project on Japanese eel resource management is a commissioned and subsidized research project of the Fisheries Agency led by Professor Hiroshi Hakoyama, in which 39 research and development institutions (13 JV institutions, 26 collaborative institutions) are participating. This annual report meeting was attended by 42 people from the Fisheries Agency, universities, prefectures and other research and development institutions who presented the results of their research on eel resources. The results of this project, which will identify trends in the ever-declining eel resource and estimate the risk of extinction, will contribute to resource management at the national and prefectural levels, as well as in countries and regions along the East Asian coast.
Meeting Agenda
Opening Remarks (Mizugaki, International Resources Section Chief) 13:15-13:20 (5 min)
Introduction of Participants (List) 13:20-13:25 (5 min)
Abstract: Invasive alien insects that cause severe damage to agricultural crops and are designated by the Plant Protection Act are called special pests. The sterile insect release method (=sterilization method) was started in 1971 to eradicate the special pest melon fly. 100 million sterile fruit flies were sprayed from helicopters every week, and in 1993, melon flies were finally eradicated from Japan. Just before eradication, data were published suggesting the appearance of females (resistant females) that could distinguish sterile males in some areas of Okinawa Island (Hibino and Iwahashi 1989, 1991), but the national and prefectural governments thoroughly sprayed huge amounts of sterile insects in areas where wild insects remained, completely eradicating them. As a result, one question remained: Did females evolve that could distinguish sterile males? Together with my students, I used a beetle Tribolium castaneum, which can be bred in Okayama, and measured the generational changes in female traits in an experimental area where sterile males and normal males were exposed to females, and in a control area where only normal males were exposed to females, by repeatedly breeding for more than 15 generations. In this seminar I would like to report and discuss the results.
We conducted a survey on the spawning migration of wild eels in Shizuoka and Kumamoto!
IFB
We conducted a spawning migration survey using pop-up tags on natural downstream eels in Shizuoka Prefecture on December 2, 2024, and in Kumamoto Prefecture on December 13, 2024.
In Shizuoka Prefecture, we set out by boat from Lake Hamana and released five individuals in an area approximately 700 meters deep.
In the Ariake Sea in Kumamoto Prefecture, we released three individuals in shallow water inside the bay.
This is the first time we have tried to collect data on eels migrating to the open ocean. We saw many dolphins from the boat!
We received cooperation from Ebisen Co., Ltd., the Fishing Shop BLUEJUNKIE, and the Kumamoto Prefectural Fisheries Research Center for this survey.
Thank you very much.
Nagano University Mitsuo Seminar students visited the Institute of Freshwater Biology!
IFB
On Thursday, December 12, 2024, 15 first-year seminar students of Professor Yoshito Mitsuo visited the Institute of Freshwater Biology as part of their seminar activities. The students were briefed about the Institute of Freshwater Biology, its research projects on river ecology and Japanese eel, and its research, education, social contributions, and history. They also toured the wild fish stocks on the premises, as well as the facilities and equipment.
The Chikuma-Shinano Rivers Research Group presented their results at the River Ecology Academic Research Presentation (Tokyo Shoken Hall)
IFB
On November 21, 2024, the Chikuma River and Shinano River Research Group presented their results at the River Ecology Academic Research Presentation at the Tokyo Shoken Hall.
Hiroshi Hakoyama* (IFB, Nagano University) On the importance of habitat continuity for riverine ecosystems and related restoration measures.
Alessandra CERA*, Sakie KODAMA, Leanne FAULKS, Hiroshi HAKOYAMA (IFB, Nagano University) Effects of water flow velocity on metabolic functionality of freshwater epilithic biofilms: a field and laboratory study.
Leanne FAULKS*, Alessandra CERA, Sakie KODAMA, Hiroshi HAKOYAMA (IFB, Nagano University) River fragmentation at the local scale: effects on biodiversity.
Takato IDO, Mei YOSHIMURA, *Masashi TOYOTA (Faculty of Engineering, Shinshu University) River channel evolution in the middle reaches of the Chikuma River as seen from cross-sectional survey data and aerial photographs
