● Publications (All Peer-reviewed)
⚪︎Corresponding author
16. ⚪︎Hasegawa R., Poulin R. & Salloum P.M.
「Testing for consistency in co-occurence patterns among bacterial taxa across the microbiomes of four different trematode parasites」
Microbial Ecology 88: 45. 2025
doi: 10.1007/s00248-025-02545-w
15. ⚪︎Hasegawa R. & Poulin R.
「Effect of parasite infections on fish body condition: a systematic review and meta-analysis」
International Journal for Parasitology 55(8-9): 417-426. 2025
doi: 10.1016/j.ijpara.2025.03.002
14. ⚪︎Hasegawa R. & Poulin R.
「Cause or consequence? Exploring authors’ interpretations of correlations between fish body condition and parasite infection」
Journal of Fish Biology 107: 658-661. 2025
doi: 10.1111/jfb.70048
13. Murakami L., ⚪︎Hasegawa R., Aruga N., Sato N., Nakamura S., Kajihara H. & Koizumi I.
「Mouth-attaching copepod Salmincola markewitschi reduces the body condition and growth of juvenile salmonid Salvelinus leucomaenis by decreasing host feeding activity: evidence from parasite removal experiment」
Canadian Journal of Zoology 103: 1-8. 2025
12. ⚪︎Hasegawa R., Uemura Y., Yamashita Y., Inoshita M. & Koizumi I.
「Highly threatened status for the relict populations of ectoparasitic copepod Salmincola californiensis in Japan」
Aquatic Conservation: Marine and Freshwater Ecosystems 35(2): e70073. 2025
11. ⚪︎Hasegawa R., Sugimoto Y. & Koizumi I.
「A new locality record of the ectoparasitic copepod Salmincola californiensis in Japan: a potential relic population with high vulnerability to extinction」
Crustacean Research 54(2025): 1–7. 2025.
doi: 10.18353/crustacea.54.0_1
10. ⚪︎Hasegawa R., Otsuki Y., Uemura Y., Furusawa C., Naka M., Kanno Y., Koizumi I.
「Positive feedback between parasite infection and poor host body condition reduces host survival in the wild」
Functional Ecology 39(3): 723–736. 2025.
9. ⚪︎Hasegawa R. & Koizumi I.
「Do mouth-infecting parasites alter the foraging ecology of host fish? A test with the parasitic copepod Salmincola markewitschi and white-spotted charr Salvelinus leucomaenis」
Freshwater Biology 70(1): e14362. 2025.
8. ⚪︎Hasegawa R., Murakami L., Aruga N., Sato N., Nakamura S. & Koizumi I.
「Host specificity of the parasitic copepod Salmincola markewitschi in an aquarium」
Fish Pathology 59(4): 139–142. 2024.
7. ⚪︎Hasegawa R. & Koizumi I.
「Consistent negative correlations between parasite infection and host body condition across seasons suggest potential harmful impacts of Salmincola markewitschi on wild white-spotted charr Salvelinus leucomaenis」
Zoological Science 41(2): 192–200. 2024.
6. ⚪︎Hasegawa R. & Koizumi I.
「Parasites either reduce or increase host vulnerability to fishing: a case study of a parasitic copepod and its salmonid host」
The Science of Nature 110: 10. 2023.
doi: 10.1007/s00114-023-01836-x
・English Press release is here
5. ⚪︎Hasegawa R., Katahira H. & Koizumi I.
「Salmincola markewitschi (Copepoda: Lernaeopodidae) or S. carpionis ? A taxonomic confusion due to high morphological variations and a requirement for revising their taxonomic status」
Folia Parasitologica 69: 025. 2022.
doi: 10.14411/fp.2022.025
4. ⚪︎Hasegawa R., & Nitta M.
「Rediscovery of Lernaeenicus ramosus Kirtisinghe, 1956 (Copepoda: Pennellidae) parasitizing the type host, comet grouper Epinephelus morrhua (Perciformes: Serranidae) from the Japanese coast, with a note on its underdeveloped head」
Biogeography 24: 25-31. 2022.
3. ⚪︎Hasegawa R., Ayer C. G., Umatani Y., Miura K., Ukumura M., Katahira H. & Koizumi I. 「Potential negative effects and heterogeneous distribution of a parasitic copepod Salmincola edwardsii (Copepoda: Lernaeopodidae) on Southern Asian Dolly Varden Salvelinus curilus in Hokkaido, Japan」
Parasitology International 87. 102529. 2023.
doi: 10.1016/j.parint.2021.102529
2. ⚪︎Hasegawa R., & Koizumi I.
「Relative importance of host dependent vs. physical environmental characteristics affecting the distribution of an ectoparasitic copepod infecting to the mouth cavity of stream salmonid」
Ecological Research 36: 1015-1027. 2021.
1. ⚪︎Hasegawa R., Yamada H., Ishihara C., Wada S.
「Personality differences in white-spotted char fry evident habitats」
Japanese Journal of Ichthyology 67 (1): 11-24. 2020．
In Japanese with English Abstract
● Under review
・Uemura Y., Otsuki Y., Hasegawa R., Naka M. & ⚪︎Koizumi I.
「Condition-specific competition? Mechanisms of local coexistence in stream salmonids under highly asymmetric competition」
（submitted: 2024/10/19）
・Uemura Y., Negoro K., Naka M., Furusawa C., Otsuki Y., Hasegawa R. & ⚪︎Koizumi I.
「Uncommon color patterns “disrupted parr marks” and biased occurrence within a metapopulation of stream-dwelling Asian Dolly Varden Salvelinus curilus」
（submitted: 2024/12/23）
・⚪︎Hasegawa R.
「Recent emergence and distributional expansion of the parasitic copepod Lernaeenicus cf. ramosus in Japanese waters revealed by web image surveys」
（submitted: 2025/5/21）
・⚪︎Hasegawa R., de Angeli Dutra D., Presswell B., Bennett J., McDougall C., Buschang K.E., Chai X. & Poulin R.
「Does bigger mean sicker? A systematic review and meta-analysis of the intraspecific relationship between host body size and parasite infection across vertebrate taxa」
（submitted: 2025/7/3）
・⚪︎Uemura Y., Hasegawa R., Taniguchi Y., Kawaguchi Y., Hasegawa K., Takeuchi Y., Hara N., Otsuki Y., Kasugai K., Oiso T., Shimoda K., Urabe H. & Koizumi I.
「Validating past predictions of local extinction in a salmonid fish under global warming: The role of overlooked proximate factors」
（submitted: 2025/8/3）
● Awards
7. Mar. 2022. Best English Presentation Award (Animal population section).
The 69th Annual Meeting of the Ecological Society of Japan (See 16 below)
6. Oct. 2021. Best oral presentation award for students.
The 67th Joint Annual Meeting of Northern Branches of the Japanese Society of Parasitology and the Japan Society of Medical Entomology and Zoology (See 13 below)
5. July. 2021. JASSO Repayment Exemption for Students with Particularly Outstanding Results
(All exemption)
4. Mar. 2021. Best poster presentation award.
The 68th Annual Meeting of the Ecological Society of Japan (See 8 below)
3. Feb. 2021. Excellent oral presentation award for master students.
Master's thesis presentation in 2020.
2. Nov. 2020. Best poster presentation award.
The 36th Annual Meeting of the Society of Population Ecology (See 6 below)
1. Nov. 2019. Excellent oral presentation award for students.
Annual Meeting of the Hokkaido Branch of Ecological Society of Japan 2019. (See 2 below)
● Grants
7. JSPS Overseas Research Fellow（April 2024~）
「Priority effects in parasite community assembly and its consequences on host fitness and ecosystem functioning」
6. JSPS Postdoctoral Fellow (PD) (declined due to acceptance of 7)
「Resolving priority effects in parasite community assembly from host immunological aspects」
5. The research grant from Yanmar Environmental Sustainability Support Association (April 2023~ Mar. 2024)
JPY ¥300,000
「Temperature-dependent effects of Salmincola edwardsii on body condition of southern Asian Dolly Varden」
4. Grant-in-Aid for Scientific Research of Lake Akkeshi and Bekanbeushi Wetland（April. 2022~Mar. 2023）
JPY ¥150,000
「Current population status of highly threatened ectoparasite Salmincola californiensis」
3. JSPS Research Fellow DC2（April. 2022~Mar. 2024）
JPY ¥1,700,000
「Priority effects in parasite community assembly and its consequences on host fitness」
2. Hokkaido University ambitious fellowship for Ph. D. student Ministry of Culture, Science and Technology（April 2021~Mar. 2022）JPY ¥360,000
1. Grant support for overseas meeting presentation by Environmental Science Alumni (1st term, 2021) JPY ¥100,000
● Presentation at conference
◯: Presenter
Under line: Hasegawa
31. ◯Hasegawa R.「Positive feedback between parasite infection and poor host body condition reduces host survival: a case study of parasitic copepod and their host freshwater salmonids」『2025 Joint Conference of the Asian Society of Ichthyologists Annual Meeting and the 12th Indo-Pacific Fish Conference』No. 284, Taipei, Taiwan. June 2025 (Oral).
30. ◯Uemura Y., Hasegawa R., Taniguchi Y., Kawaguchi Y., Takeuchi Y., Hara N., Otsuki Y., Oiso T., Shimoda K., Urabe H., Hasegawa K., Koizumi I. 「Evaluation of a model for predicting the local extinction of Dolly Varden due to global warming」『The 45th Annual Meeting of Gyorui Keito Kenkyu-kai』No1, Sapporo, Japan. Dec. 2024 (Oral).
29. ◯Hasegawa R., Poulin R.「Effect of parasite infections on fish body condition: a systematic review」『Parasites in the Pacific 2024 Conference』P2-024, Aukland, New Zealand. September 2024 (Oral).
28. ◯Uemura Y., Hasegawa R., Takeuchi Y., Hasegawa K., Hara N., Otsuki Y., Koizumi I.「Local extinction of a freshwater salmonid by global warming: comparison of the current distribution with 30 years ago」『The 71st Annual Meeting of the Ecological Society of Japan』P2-024, Yokohama, Japan, Mar. 2024 (Poster).
27. ◯Hasegawa R., Uemura Y., Miura K., Koizumi I.「Evaluating the temperature-dependent effects of parasites on cold-water salmonids」『The 71st Annual Meeting of the Ecological Society of Japan』P2-023, Yokohama, Japan, Mar. 2024 (Poster).
26. ◯Uemura Y., Hasegawa R., Takeuchi Y., Hasegawa K., Hara N., Otsuki Y., Koizumi I.「Has the distribution of southern Asian Dolly Varden decreased with global warming over the past 30 years? 」『The 44th Annual Meeting of Gyorui Keito Kenkyu-kai』No. 1, Sapporo, Japan. Dec. 2023 (Oral).
25. ◯Hasegawa R., Uemura Y., Yamashita Y., Inoshita M., Koizumi I.「Salmincola californiensis, a nearly extinct parasite species from Japan」『The 44th Annual Meeting of Gyorui Keito Kenkyu-kai』No. 9, Sapporo, Japan. Dec. 2023 (Oral).
24. ◯Hasegawa R., Uemura Y., Miura K., Koizumi I.「Coinfection patterns of three ectoparasites on congeneric stream salmonids」『39th Annual Meeting of the Society of Population Ecology』P22, Sapporo, Japan. Oct. 2023 (Poster).
23. ◯Uemura Y., Otsuki Y., Hasegawa R., Naka M., Koizumi I.「Mechanisms of spatial segregation under highly asymmetric competition in juvenile charr: a field experiment」『The 10th International Charr Symposium』P9, Nikko, Japan. June 2023. Oral, English. Peer reviewed.
22. ◯Hasegawa R., Uemura Y., Miura K., Koizumi I.「Coinfection patterns of three ectoparasites on congeneric stream salmonids and its impacts on host fishes」『The 10th International Charr Symposium』P2, Nikko, Japan. June 2023. Oral, English. Peer reviewed.
21. ◯Uemura Y., Otsuki Y., Hasegawa R., Naka M., Koizumi I.「Mechanisms of spatial segregation under highly asymmetric competition in juvenile salmonids: a field experiment」『The 70th Annual Meeting of the Ecological Society of Japan』A03-03, Sendai, Japan (Online). Mar. 2023. Oral, English.
20. ◯Hasegawa R., Uemura Y., Miura K., Koizumi I.「Elucidating the coinfection patterns of three species of parasites infecting stream salmonid: effects on host condition and geographic distribution」『The 70th Annual Meeting of the Ecological Society of Japan』P2-019, Sendai, Japan (Online). Mar. 2023. Poster, Japanese.
19. ◯Uemura Y., Otsuki Y., Hasegawa R., Koizumi I.「Parapatric distribution allowed by temperature-dependent competition: a field assessment in two congeneric fishes.」『The 13th International Congress of Ecology (INTECOL2022)』329, Geneva, Swizerland (Online). August 2022. Poster, English. Peer reviewed.
18. ◯Hasegawa R., Otsuki Y., Uemura Y., Furusawa C., Naka M., Koizumi I.「Positive feedback of parasite infection and reduced host condition: a test by mark-recapture of stream salmonid and parasitic copepod」『The 15th International Congress of Parasitology (ICOPA2022)』ID113, Copenhagen, Denmark. Aug. 2022. Oral, English. Peer reviewed.
17. ◯Uemura Y., Otsuki Y., Hasegawa R., Naka M., Koizumi I. 「Do population density and individual body condition predict the habitat quality of stream salmonids?」『The 69th Annual Meeting of the Ecological Society of Japan (ESJ69)』Fukuoka, Japan (Online), P3-324, Mar. 2022. Poster, Japanese.
16. ◯Hasegawa R. & Koizumi, I「Do impacts and infection levels of parasite change across seasons? A test in stream salmonid and parasitic copepod system 」『The 69th Annual Meeting of the Ecological Society of Japan (ESJ69)』B03-04, Fukuoka, Japan (Online). Mar. 2022. Oral, English. Best English Presentation Award.
15. ◯Uemura Y., Otsuki Y., Hasegawa R., Naka M., Koizumi I. 「Temperature-dependent competition in stream salmonids: a field assessment considering biotic interactions and abiotic factors」『The 42th Annual Meeting of Gyorui Keito Kenkyu-kai』Sapporo, Japan (Online). Dec. 2021. Oral, Japanese.
14. ◯Hasegawa R. & Koizumi I.「Are parasitized fish not vulnerable to fishing? Impacts of the mouth infecting copepods on host fish, white-spotted charr」『The 42th Annual Meeting of Gyorui Keito Kenkyu-kai』Sapporo, Japan (Online). Dec. 2021. Oral, Japanese.
13. ◯Hasegawa R. & Koizumi I.「Are parasitized fish not vulnerable to fishing? Impacts of the mouth infecting copepods on host fish, white-spotted charr」『The 67th Joint Annual Meeting of Northern Branches of the Japanese Society of Parasitology and the Japan Society of Medical Entomology and Zoology』Asahikawa, Japan (Online). Oct. 2021. Oral, Japanese. Best Oral Presentation Award.
12. ◯Uemura Y., Otsuki Y., Hasegawa R., Koizumi I. 「Habitat assessment for stream charrs: a field test focusing on the population density and individual body condition」『The 55th Annual Meeting of the Ichthyological Society of Japan』 68, Online. Sep. 2021. Poster, Japanese.
11. ◯Hasegawa R. & Koizumi I.「Are parasitized fish not vulnerable to fishing? Impacts of the mouth infecting copepods on host fish, white-spotted charr」『The 55th Annual Meeting of the Ichthyological Society of Japan』69, Online. Sep. 2021. Poster, Japanese.
10. ◯Uemura Y., Otsuki Y., Hasegawa R., Koizumi I.「Condition-specific competition in native charrs: a field test considering abiotic factors and biotic interactions」『The 2021 Ecological and Evolutionary Ethology of Fishes Biennial Conference (EEEF2021)』Day1-005, Berkeley, USA(Online). July 2021. Oral, English. Peer reviewed.
9. ◯Uemura Y., Otsuki Y., Hasegawa R., Koizumi I.「Temperature-dependent competition in stream salmonids: a field test considering biotic interactions and abiotic factors」『The 68th Annual Meeting of the Ecological Society of Japan (ESJ68)』G03-07, Okayama (Online). Mar. 2021. Oral, English.
8. ◯Hasegawa R., Otsuki Y., Uemura Y., Furusawa C., Naka M., Koizumi I.「Disentangling the causal relationship between parasite infection and low host condition」『The 68th Annual Meeting of the Ecological Society of Japan (ESJ68)』P1-015, Okayama, Japan (Online), Mar. 2021. Poster, Japanese. Best Poster Presentation Award.
7. ◯Uemura Y., Otsuki Y., Hasegawa R., Koizumi I.「Condition-dependent competition in stream salmonids: a field test considering biotic interactions and abiotic factors.」『Annual Meeting of the Hokkaido Branch of Ecological Society of Japan 2020』Sapporo, Japan (Online). Dec. 2020. Oral, Japanese.
6. ◯Hasegawa R., Otsuki Y., Furusawa C., Uemura Y., Naka M., Koizumi I.「Do parasite infections cause new parasite infections?: a mark-recapture approach focusing on white-spotted charr and their parasitic copepods Salmincola carpionis」『The 36th Annual Meeting of the Society of Population Ecology』PP017, Sendai, Japan (Online). Nov. 2020. Poster, Japanese. Best Poster Presentation Award.
5. ◯Hasegawa R. & Koizumi I.「Factors affecting the abundance of parasitic copepods that attach to the mouth cavity of salmonids」『The 67th Annual Meeting of the Ecological Society of Japan (ESJ67)』P1-PA-023, Nagoya, Japan. Mar. 2020. Poster, Japanese. Canceled due to covid-19
4. ◯Murakami L., Hasegawa R., Otsuki Y., Koizumi I., Kajihara H.,「Prevalence of parasitic copepods in the pools and shallows」『The 67th Annual Meeting of the Ecological Society of Japan (ESJ67)』P1-PA-023, Nagoya, Japan. Mar. 2020. Poster, Japanese. Canceled due to covid-19
3. ◯Hasegawa R. & Koizumi I.「Heterogeneous distribution and effects on the host of parasitic copepod Salmincola carpionis infecting on white-spotted charr」『The 41th Annual Meeeting of Gyorui Keito Kenkyu-kai』Sapporo, Japan. Dec. 2019. Oral, Japanese.
2. ◯Hasegawa R. & Koizumi I.「Heterogeneous distribution and effects on the host of parasitic copepod infecting on white-spotted charr」『Annual Meeting of the Hokkaido Branch of Ecological Society of Japan 2019』Tomakomai, Japan. Nov. 2019. Oral, Japanese. Excellent Oral Presentation Award for students.
1. ◯Hasegawa R., Yamada H., Morimura H., Ishihara Y., Wada S.「Personality differences between habitats in juvenile white-spotted charr: focusing on the effects of dams」『The 66th Annual Meeting of the Ecological Society of Japan (ESJ66)』P1-093, Kobe, Japan. Mar. 2019, Poster, Japanese.
● Seminar and workshop
11. ◯Hasegawa R.「How to use “Notion” in research activities」『Zoo Lunch, a seminar for postgraduate students of Department of Zoology』Dunedin, New Zealand. July 2025 (Oral).
10. ◯Hasegawa R.「Web-posted images revealed the temporal dynamics of the marine parasitic copepods Lernaeenicus ramosus」『Department of Zoology Postgraduate Colloquium 2024』Dunedin, New Zealand. October 2024 (Poster).
9. ◯Hasegawa R.「Ecology of parasitic copepods infecting freshwater salmonids: effects on host health and geographic distribution」『Departmental seminar series, Department of Zoology, University of Otago』Dunedin, New Zealand. September 2024 (Oral).
8. ◯Hasegawa R. 「Ecological study of the lernaeopodid copepod of the genus Salmincola -Geographic distribution and causality between host body condition and infections」『CIGENE seminar series, Norwegian University of Life Sciences (NMBU)』Oslo, Norway (Online), Nov. 2022 (Oral). Invited speaker.
7. ◯Hasegawa R.「Ecology of Salmincola sp. infecting on white-spotted charr in wild streams」『The 91th Annual Meeting of the Japanese Society of Parasitology, "The 36th free-meeting of Ecology and Epidemiology"』Obihiro, Japan. May. 2022. Oral, Japanese. Invited speaker.
6. ◯Hasegawa R.「Ecological study of the lernaeopodid copepod of the genus Salmincola -Geographic distribution and causality between host body condition and infections」『Seminar at Evolutionary Biology Group, University of Bergen』 Bergen, Norway (Online). April 2022 (Oral).
5. ◯Hasegawa R.「Disentangling the causal relationship between parasite infection and low host condition」『ISM seminar - Statistical model for ecological data』Tachikawa, Japan. Jan. 2022. Oral, Japanese.
4. ◯Hasegawa R.「Ecology of Salmincola sp. infecting on white-spotted charr in wild streams」『The 85th Annual Meeting of the Japanese Society of Limnology (workshop by Limnology of youth, E-kai)』Tokyo(Online). Sep. 2021. Oral, Japanese.
3. ◯Hasegawa R.「Determinants of basin-wide distribution and effects on hosts of parasitic copepods infecting white-spotted charr」『The 13th Annual Meeting of Salmon Science Society, Night session』Sapporo, Japan (Online). Dec. 2020. Oral, Japanese. Invited speaker.
2. ◯Hasegawa R. & Koizumi I.「Heterogeneous distribution and effects on the host of parasitic copepod infecting on white-spotted charr」『The 1st Meeting of Master Course Research Seminar- learning statistical analysis with R』Sapporo, Japan. Jan. 2020. Oral, Japanese.
1. ◯Hasegawa R. & Koizumi I.「Host-patasite relationship between Salmincola carpionis and wild white-spotted char」『 Nord University Lunch time Seminar』 Bode, Norway. Sep. 2019. Oral, English.
● Outreach
10. Kiwi Conservation Club (KCC) 2025 staff "Parasites exhibition"@Dunedin, New Zealand
9. BugDay2025 staff "Parasites exhibition"@Dunedin, New Zealand
8. Oct. 2023. Provide a photo of Gnathanodon speciosus (NHK)
7. Sep. 2023. Exhibition of parasites infecting salmonid fishes@Sapporo Salmon museum, Sapporo
6. July 2023. Sapporo culture night "Observation on fish parasites"@ Nishioka park, Sapporo
5. Oct. 2022-. Introductions for parasites infecting salmonid fish@Sapporo Salmon museum, Sapporo
4. Nov. 2020. Provide a photo of Hemitripterus villosus (Japan TV)
3. July 2019. Environmental Education for elementary school students @ Makomanai, Sapporo
2. 2017 April-2018 Mar.. Volunteer at Hokkaido University Museum (Management of fish collections)
1. 2016-2024 WEB-sakana-zukan staff
● Reviewer experience
・Japanese Journal of Ichthyology
・Molecular Biology Report
・Transactions of the American Fisheries Society
・Crustacean Research
・PeerJ
・Aquatic Ecology
・Journal of Fish Biology
・Plankton and Benthos Research
・Marine Biodiversity
・Proceedings of the National Academy of Sciences
・Proceedings of the Royal Society B: Biological Sciences