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Advancing the classification of midges—small river insects—for the benefit of various quarters
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Professor Koichiro Kawai pursues research into midges—small river insects. Even if you didn’t know what they are called, you have probably seen these insects swarming in a column under an outdoor light. Indeed, midges are very common insects, and there are about 1,500 species of midges found in Japan alone.
Professor Kawai says, “Particularly in autumn, due to their phototaxis, we often see midges swarming in a column around convenience stores near rice fields, thereby hindering business. As well, plagues of midges occur around the enclosed embankment of Isahaya Bay. For these reasons, midges carry a negative image as insect pests.”
On the other hand, according to Professor Kawai, midges feed on sludge at the bottom of rivers. If they didn’t eat sludge, it would further accumulate on the bottom of rivers that have been eutrophied with agricultural effluents. The rivers would then create anaerobic conditions, in which methane and hydrogen sulfide are generated. |
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“In exaggerated terms, midges play such an important role that people cannot continue living in a region if there are no midges,” he said.
The greatest question in studies of midges is why there are so many varieties of midge species.
He says, “How have midges speciated into so many species? Probably because midges have differentiated in order to adapt themselves to various environments, so as to make the most of their environments. We are conducting a project to find an answer to this question, together with people from the Ministry of the Environment.”
In this context, researchers must first advance the classification of midges. However, there are only 20 researchers specializing in midge studies in Japan, with only five experts, including Professor Kawai, capable of classifying midges. For this reason, the classification effort has made little progress. |
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Progressing from the classification of midges to the establishment of water quality indicators, while also expecting younger researchers to take over his research
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“So far I have given scientific names to about 50 varieties of midges as new species,” says the professor. These new species have “Kawai” at the end of their names.
He added that the real thrill of this research comes in the moment of joy when he can discover something that no one has ever known before.
Moreover, Professor Kawai aims to make effective use of midges as “biological indicators.”
“When the water quality changes, the species of midges living there will also change. Accordingly, if we survey what kind of species live in a habitat, we can acquire data on the average water quality there. In other words, these species function as biological indicators,” explains Professor Kawai. |
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According to the professor, a physicochemical indicator, which is created by analyzing a water sample, is just a momentary value, and the numerical water quality data derived from that value may be just for the sake of convenience. By contrast, a biological indicator is more reliable and entails a lower cost to establish.
“This is very important work, so we are now committed to establishing such a biological indicator. Our research is making considerable progress and coming close to practical application,” he said.
When asked about his future goals, Professor Kawai answered, “From Hiroshima University, I want to publish a book covering all the species of midges in Japan, in order to enable everyone to easily classify midges. To realize this goal, I will demonstrate what fun this research is, so as to foster researchers who will work with us and become my successors.”
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| The more he conducts research into freshwater organisms, the more he is fascinated by their mysterious attractiveness, he says with a boyish smile. |
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Enthusiastic about research on the Gogi charr, a fish “that apparently travels over mountain ridges“ and fulfilling the mission of increasing children’s interest in organisms
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Another research theme that Professor Kawai is enthusiastic about is the “Gogi’ (Salvelinus leucomaenis imbrius), a subspecies of Japanese common charr. This freshwater fish species is found only in the Chugoku mountain region in Japan. The Gogi charr is characterized by spots on its head.
Professor Kawai says, “I wonder why the Gogi has come to possess these spots on the long road of evolution. To find the answer, I wish to study not only the Gogi, but also all other species of Japanese charr.”
In the first place, it was Japanese charr that changed the mind of Professor Kawai, who initially wanted to be a veterinarian, to aspire to become a researcher. “Looking back on that time, once when I happened to go fishing with my father, in the fish tank I saw Japanese charr swimming, and I instantly thought how cool the fish was! I was so fascinated with the Japanese charr that I could barely think about anything else,” he says with a smile.
Among Japanese charr, he started to study the Gogi, because he was interested in the possibility that the fish may have traveled across a mountain ridge to the other side of the mountain. “After a heavy rainfall, we can see the Gogi charr splash across a narrow run-off stream. Whenever I see this scene, I cannot help thinking that in the past, the Gogi charr must have traveled from one side of a mountain to the other.”
He has also compiled a lot of data that support his assumption, including the DNA testing results of fish distributed in the relevant region. While continuing his research, Professor Kawai serves as a lecturer of insect classes designed for children. |
“Today we have fewer and fewer opportunities to commune with other living things. Many people are less interested in other creatures, and it is much more difficult for them to find out about the differences in their shape and the like. I therefore believe that it is all the more important to encourage people of the next generation to develop an interest in organisms, and that it is our mission to make every possible effort to achieve this goal.”
He is busy pursuing various research themes every day, but he feels truly happy about it. |
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| Koichiro Kawai |
Professor
Laboratory of Benthos Ecology
Department of Bioresource Science
April 1, 1987 – December 31, 1993 Research Assistant, School of Medicine, Toyama Medical and Pharmaceutical University
January 1, 1994 – November 21, 2007 Associate Professor, School of Applied Biological Science, Hiroshima University
November 1, 2011 – present Professor, School of Applied Biological Science, Hiroshima University
Posted on Nov 17, 2014
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