Publications, team milestones, outreach highlights, software releases & field updates
Temp-Pref Tracker v.2.5 is now available on the Fish Resilience Program website. This update adds optional internal core/body temperature estimation based on specimen mass and chamber temperature, updates the installer package, and includes the revised v.2.5 user manual for download.
Learn more & download
CTmax Tracker v1.2 is now available through the Fish Resilience Program website. The software was developed for Critical Thermal Maximum experiments in fish and other aquatic ectotherms. The software combines interactive specimen tracking, live DAQ-linked temperature monitoring, ramp control, CTmax event logging with internal temperature estimation, and CSV export in a single Windows desktop application.
Learn more & download
Congratulations to ʻAʻaliʻi Kelling, whose research on imu (traditional Hawaiian fish houses) has been showcased in Hana Hou!, the in-flight magazine of Hawaiian Airlines. The feature highlights ʻAʻaliʻi’s work exploring how these culturally significant structures influence juvenile fish behavior and habitat use — a wonderful example of integrating Native Hawaiian traditional knowledge with modern marine science.
Read the article (PDF)
PhD candidate Jasmine Reighard has been recognized among the top 10 most cited authors for the journal Reviews in Aquaculture among 2024 publications. Her article “Salinity tolerance of fishes: Experimental approaches and implications for aquaculture production” was recognized as a top cited article by Wiley. Amazing accomplishment!
The lab’s coral reef fish research is featured in a full documentary episode on Voice of the Sea, a PBS Hawaiʻi television series produced by Hawaiʻi Sea Grant. The episode, “Clean Water, More Fish, Healthy Reef” (Season 13, Episode 2), explores our work in Kāneʻohe Bay and how ʻāina stewards are restoring streams and reefs.
▶ Watch on YouTube More outreach →
Johansen Lab student and Hawaiʻi Sea Grant Fellow Leon Tran has been selected for a nationally competitive fisheries fellowship. Leon’s research integrates species distribution modeling with experimental physiology to predict how coral reef fish distributions will shift under environmental change.
Read article (UH News)
Honolulu Civil Beat published a feature on the lab’s work showing how herbivorous reef fish help protect coral reefs — and what happens when sediment runoff undermines their ability to do so.
More outreach →
Congratulations to ʻAʻaliʻi Kelling for successfully defending his M.S. thesis on the influence of Native Hawaiian imu (fish houses) on juvenile fish behavior! ʻAʻaliʻi has immediately rejoined the Johansen Lab as a Ph.D. student, where he will continue his research on fish-habitat interactions and cultural resource management.
Meet the team
Vaughan GO, Ripley DM, Mitchell MD, McParland D, Johansen JL, Shiels HA, Burt JA (2025) Narrow Margins: Aerobic Performance and Temperature Tolerance of Coral Reef Fishes Facing Extreme Thermal Variability. Global Change Biology, 31(3), p.e70100.
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Brijs J, *Moore C, *Schakmann M, *Souza T, *Grellman K, *Tran LL, *Patton PT, Johansen JL (2025) Eat more, often: The capacity of piscivores to meet increased energy demands in warming oceans. Science of The Total Environment, 973, p.179105.
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*Souza T, Brijs J, *Tran L, Crowder L, Johansen JL (2025) Herbivore functions in the hot-seat: Resilience of Acanthurus triostegus to marine heatwaves. PLoS One, 20(1), p.e0318410.
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*Tiddy IC, *Neill CM, *Rosén A, *Hasegawa Y, Domenici P, Johansen JL, Steffensen JF (2025) Effects of social environment and energy efficiency on preferred swim speed in a marine generalist fish, pile perch (Phanerodon vacca). J Exp Biol, 228(5).
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This June, several Johansen Lab researchers and collaborators traveled to Taipei, Taiwan, for the 2025 Joint Conference of the Asian Society of Ichthyologists Annual Meeting and the 12th Indo-Pacific Fish Conference. Jake Snyder presented the first chapter of his PhD thesis on modeling coral reef and herbivorous fish outcomes, while Jasmine Reighard presented her research quantifying the metabolic costs of sediment exposure using 3D-printed respirometry chambers. Lisa McManus also participated.
In April, PI Jacob Johansen and postdoc Linda Eggertsen visited Prof Brett Taylor at the Marine Lab at University of Guam. Profs Howard Choat and Andy Hoey (JCU) also joined the trip. We had a productive week at the Marine Lab working on samples collected in Hawaii as part of the “Mud to Makai” project, studying effects of land-based sediment runoff on herbivorous fishes. Prof Choat also visited us at HIMB on the way back to Australia. A huge thank you to Brett for having us!
Congrats to Kat for becoming the first student to graduate from the Johansen Lab following the successful defense of her master’s thesis! We wish her well in her future endeavors and hope to see her often. What better way to celebrate than a nice climb outdoors with food, drinks, and friends!
Katherine defended her M.S. thesis on the effects of enhanced sediment-laden algal turfs on herbivorous fish interactions. She was the first student to complete their degree in the Johansen Lab.
Find out in the Johansen Lab’s publication, “Impacts of ocean warming on fish size reductions on the world’s hottest coral reefs”, published in Nature Communications. The news release hit nearly all the main dailies in the UAE including The National, Gulf News, Al Etihad, and Al Khaleej. This research scored in the top 5% of all research outputs by Altmetric.
Leon Tran and Jasmine Reighard traveled to Prague, Czech Republic, to present their preliminary results at the Society of Experimental Biology. Jasmine presented her poster on “Metabolic responses to suspended sediment in a Hawaiian herbivorous reef fish”, while Leon presented his on “Body size variation and sensitivity to marine heatwaves in the day octopus (Octopus cyanea)”. Leon received the Best Early Career Research Award for his poster session, sponsored by Functional Ecology. Meanwhile, Jacob Johansen, Jake Snyder, and Mathias Sorensen traveled to Naples, Italy, where Mathias presented his preliminary results at the European Coral Reef Symposium.
Katherine was recently hired by The Nature Conservancy as their Coastal Science Specialist. In her new role, she will support water quality strategies to prevent land-based pollutants from impacting marine ecosystems across the Hawaiian islands. Way to utilize your graduate experience!
The Nature Conservancy Hawaiʻi
*Frank LC, *Prescott LA, *Scott ME, Domenici P, Johansen JL, Steffensen JF (2024) The effect of progressive hypoxia on swimming mode and oxygen consumption in the pile perch, Phanerodon vacca. Frontiers in Fish Science, 2, 1289848.
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Shane Ribovich has joined the Fish Resilience Program as Lab Manager, overseeing day-to-day operations of the Johansen Lab at HIMB including the experimental seawater systems and field equipment.
Meet the team
The RECOVER Virtual Lab — an interactive online tool developed with the lab’s research — now lets K–12 and college students explore how oil spills affect fish swimming performance. Freely available as a STEM education resource.
Try it out
ʻAʻaliʻi Kelling, Jasmine Reighard, and Leon Tran traveled to Kauaʻi during spring break to lead an educational workshop for high school students about the traditional Hawaiian practices of Imu (Fish Houses).
*Tran LL, Johansen JL (2023) Seasonal variability in resilience of a coral reef fish to marine heatwaves and hypoxia. Global Change Biology, 29(9), 2522–2535.
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We are happy to welcome our newest member of the team, Dr. Linda Eggertsen. Linda is an extremely skilled field biologist and we look forward to her work on fish herbivory across terrigenous runoff gradients.
Meet the team
We said a bittersweet goodbye to our Post-Doc researcher Jeroen Brijs as his fellowship at the Johansen Lab has come to a close. We wish him all the best in his future endeavors and look forward to his publications about the effects of marine heatwaves on Hawaiian coral reef fish. You will be missed around the lab Jeroen!
We are happy to welcome ʻAʻaliʻi Keling (MSc) and Jonathan Rosen (MSc) to our lab, both of whom are working on ways to improve fish recruitment and health in Hawaiʻi.
Meet the team
The Johansen Fish Resilience Lab is happy to announce that we just received a generous NSF grant to study the effect of sediment runoff on herbivorous fish functions. This project will start in February 2023.
We’re super excited to be officially adding M.S. student Katherine Grellman to our lab team! Kat is a familiar face to the lab as she has helped out with previous field work and other projects. Now, Kat will be researching the effects of enhanced sediment-laden algal turfs on herbivorous fish interactions!
Big congratulations to PhD student Leon Tran for passing his oral comprehensive exam for the UHM Marine Biology Graduate Program. Good work Leon!
Jasmine will be studying how declining water quality affects reef fish stress responses! She was also awarded a grant from the National Science Foundation Graduate Research Fellowship Program (NSF GRFP) to fund her research.
*Kimura H, *Pfalzgraff T, *Levet M, *Kawabata Y, Steffensen JF, Johansen JL, Domenici P (2022) Escaping from multiple visual threats: modulation of escape responses in Pacific staghorn sculpin (Leptocottus armatus). J Exp Biol 225(9).
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Nadler LE, McCormick MI, Johansen JL, Domenici P (2021) Social familiarity improves fast-start escape performance in schooling fish. Communications Biology 4(1), 1–10.
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Congratulations to Leon Tran for advancing from the M.Sc. to the Ph.D. track in the UHM Marine Biology Graduate Program. Well deserved!
Brijs J, Føre M, Gräns A, Clark TD, Axelsson M, Johansen JL (2021) Bio-sensing technologies in aquaculture: how remote monitoring can bring us closer to our farm animals. Philosophical Transactions of the Royal Society B 376(1830), 20200218.
Read paper
*Schakmann M, *Becker V, *Soegaard M, Johansen JL, Steffensen JF, Domenici P (2021) Latency of mechanically stimulated escape responses in the Pacific spiny dogfish, Squalus suckleyi. J Exp Biol 224(3), jeb230698.
Read paper (JEB)
*Khursigara AJ, *Rowsey LE, Johansen JL, Esbaugh AJ (2021) Behavioral changes in a coastal marine fish lead to increased predation risk following oil exposure. Environ. Sci. Technol. 55(12), 8119–8127.
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*Nay T, Hoey AS, Rummer JL, Steffensen JF, Johansen JL (2021) Species interactions alter the selection of thermal environment in a coral reef fish. Oecologia, 1–9.
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*Nay TJ, Longbottom RJ, *Gervais CR, Johansen JL, Steffensen JF, Rummer JL, Hoey AS (2021) Regulate or tolerate: Thermal strategy of a coral reef flat resident, the epaulette shark, Hemiscyllium ocellatum. J Fish Biol 98(3), 723–732.
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Johansen JL, Nadler LE, *Habary A, *Bowden AJ, Rummer JL (2021) Thermal acclimation of tropical fishes to marine heat waves. eLife 10, e59162.
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*Khursigara AJ, Johansen JL, Esbaugh AJ (2021) The effects of acute crude oil exposure on growth and competition in the red drum, Sciaenops ocellatus. Science of the Total Environment 751, 141804.
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New paper out today in Nature Communications: extreme environmental conditions reduce coral reef fish biodiversity and productivity. This study demonstrated how marine heatwaves dramatically reshape reef fish communities on the world’s hottest reefs.
Read paper (Nature Communications)
Mathias will be investigating the effects of sedimentation and turbidity on coral reef fishes.
Jeroen will be investigating the effects of ocean warming on feeding energetics in reef fishes.
Congratulations to M.Sc. student Leon Tran for receiving the prestigious National Science Foundation Graduate Research Fellowship Program (NSF GRFP) award. Well done!