FY2018 Annual Report

Marine Biophysics Unit

Associate Professor Satoshi Mitarai



Marine Biophysics Unit will develop forecasting system for the coastal ocean circulation processes around Okinawa and implement a validated connectivity assessment tool, coupling available modeling and observation techniques. This modeling tool will help marine biologists and genetics estimate rates of geneticists estimate rates of gene flow among sites, enable public agencies to build and evaluate marine protected areas based on population connectivity, and provide marine ecologists with a modeling system for predicting the global and long-term dynamics of the marine ecosystem. Marine Biophysics Unit was established on Sep. 1, 2009 when Satoshi Mitarai joined OIST.

1. Staff

  • Satoshi Mitarai, (September 2009 –)
  • Yuichi Nakajima, Staff Scientist (August 2013 –)
  • Angela Ares Pita, Postdoctoral Scholar (August 2017 –)
  • Marine Le Gal, Postdoctoral Scholar (September 2017 –)
  • Kirk Sato, Postdoctoral Scholar (September 2017 – June 2019)
  • Kazumi Inoha, Technician (April 2015 –)
  • Akinori Murata, Technician (March 2018 – March 2019) 
  • Hiroshi Izumi, Technical Staff (February 2018 – November 2018)
  • Otis Brunner, Graduate Student (April 2017 –)
  • Patricia Wepfer, Graduate Student (January 2014 – November 2018)
  • Maki Thomas, Graduate Student (September 2015 –)
  • Margaret Mars Brisbin, Graduate Student (September 2015 –)
  • Po-Shun Chuang, Graduate Student (September 2015 –) 
  • Carrascal Tristancho Juan Fernando, Graduate Student (January 2018 – May 2019)
  • Juan Pablo Martin Diaz, Research Intern (July 2018 – February 2019) 
  • Conover Asa, Research Intern (January 2019 – June 2019)
  • Akiko Guzman, Research Unit Administrator (March 2017 – April 2018)
  • Masako Okabe, Research Unit Administrator (April 2018 – February 2019)
  • Seira Arakaki, Research Unit Administrator (June 2018 – January 2019)
  • Tomoko Yoshino, Research Unit Administrator (March 2019  –)

2. Collaborations

2.1 Larval dispersal of coral reef species

  • Type of collaboration: Joint research
  • Researchers:
    • Prof. K. Sakai, University of the Ryukyus
    • Prof. M. Nakamura, Tokai University

2.2 Larval dispersal of hydrothermal vent species

  • Type of collaboration: Joint research
  • Researchers:
    • Dr. H. Yamamoto, Japan Agency for Marine-Earth Science and Technology
    • Dr. Y. Furushima, Japan Agency for Marine-Earth Science and Technology
    • Dr. D. Lindsay, Japan Agency for Marine-Earth Science and Technology
    • Dr. H. Watanabe, Japan Agency for Marine-Earth Science and Technology
    • Dr. M. Sunamura, Japan Agency for Marine-Earth Science and Technology
    • Dr. C. Chen, Japan Agency for Marine-Earth Science and Technology

2.3 Regional ocean circulation modeling

  • Type of collaboration: Joint research
  • Researchers:
    • Prof. J. McWilliams, University of Californina, Los Angeles
    • Dr. A. Shchepetkin, University of Californina, Los Angeles
    • Prof. Y. Uchiyama, Kobe University

2.4 Okinawa coastal ocean observing system

  • Type of collaboration: Joint research
  • Researchers:
    • Okinawa Prefectural Fisheries Research and Extension Center
    • 11th Japan Regional Coast Guard

2.5 Mesophotic coal ecosystem diversity and spatial distribution along the western cost of Okinawa

  • Type of collaboration: Joint research
  • Researchers:
    • Prof. J. Reimer, University of the Ryukyus

2.6 Coral ecosystem diversity and spatial distribution throughout the islands of Okinawa

  • Type of collaboration: Joint research
  • Researchers:
    • The Regents of the University of California, UC San Diego’s Scripps Institution of Oceanography

3. Activities and Findings

3.1 First evidence of asexual recruitment of <i>Pocillopora acuta</i> in Okinawa Island using genotypic identification

Okinawa Island is located near the center of the Nansei Islands (∼24–31◦N), at a relatively high latitude for coral reefs. Nevertheless, more than 80 coral genera (over 400 species) are abundant in the Nansei Islands. Since March, 2017, scleractinian corals have been held in an outdoor tank at the OIST Marine Science Station at Seragaki, Onna with natural sea water flow-through in order to be used in molecular biological and physiological studies. In January, 2018, we found small pocilloporid-like colonies suspected to have originated asexually. We collected 25 small colonies and measured their sizes and weights. Also, we validated the classification and clonality of the colonies using a mitochondrial locus and nine microsatellite loci. Almost all of the small colonies collected in the outdoor tank were ≤1 cm in both width and height. The weight of dried skeletons ranged from 0.0287 to 0.1807 g. Genetic analysis determined that they were, in fact, <i>Pocillopora acuta</i>. Only one mitochondrial haplotype was shared and two microsatellite multilocus genotypes were detected (20 colonies of one and four colonies of the other). The mitochondrial haplotype and one microsatellite multilocus genotype for 20 colonies corresponded to those of one <i>P. acuta</i> colony being kept in the tank. One small colony matched both multilocus genotypes. This may have been a chimeric colony resulting from allogenic fusion. These small colonies were not produced sexually, because the only potential parent in the tank was the aforementioned <i>P. acuta</i> colony. Instead, they were more likely derived from asexual planula release or polyp bail-out. Corals as <i>Pocillopora acuta</i> have the capacity to produce clonal offspring rapidly and to adapt readily to local environments. This is the first report of asexual reproduction by planulae or expelled polyps in <i>P. acuta</i> at Okinawa Island.

Figure 1: 

Location, outdoor tank, and coral colonies. (A) A map of the Nansei Islands and the location of the OIST Marine Science Station, Onna Village Fisheries Cooperative Association, and Zampa in Okinawa Island. Original maps were downloaded from Google Earth. Map data: Google Earth, Image Land- sat/Copernicus, Data SIO, NOAA, US Navy, NGA, GEBCO. (B, C) Coral colonies maintained under natural sea water flow in the outdoor tank. (D) Small colonies were discovered in the tank on January, 2018. These photographs in B, C, and D were taken by Yuichi Nakajima.

3.2 Landscape genetic method to explain intra- and inter-island propagule transport of mangrove species

Understanding migration system is key to set an effective and efficient MPA in order to maintain population connectivity for combatting various environmental changes. We argue that this concept also applies to fringe mangrove habitats particularly in island systems where mangrove population connectivity is mainly maintained by self-recruitment or (and) population connectivity through ocean currents. Mangrove migration system in island system is particularly understudied though the rate of habitat loss is problematic. This project focuses on the migration system of a mangrove species, Rhizophora stylosa, in an archipelago in the northern West Pacific region. R. stylosa is a part wide spread in Indo-West Pacific region. We found how differences in landscape of local habitat may affect the migration patterns among islands by using landscape genetic method. We sampled at total of 22 coastal areas over four different islands that are lying over the distance of 500 km. The genetic results are also compared with ocean current observational data. Low Fst values (< 0.1) were observed only among Iriomote, Ishigaki and Miyako islands, and only from 15% of total pairs. Migrations source populations were only observed in Ishigaki island (Fig.3). However, from in-situ drifter experiments, we found the concentrated physical connectivity through ocean currents among the islands (Fig1). The discrepancy of genetic and oceanographic connectivity may suggest that mangrove propagule’s dispersal maybe dominantly affected by more local hydrodynamics including inner reef ocean current, wind or rather wave driven forces.

4. Publications

4.1 Journals​

  1. Monismith, S. G., Barkdull, M. K., Nunome, Y., Mitarai, S. Transport Between Palau and the Eastern Coral Triangle: Larval Connectivity or Near Misses. Geophysical Research Letters, doi:doi: 10.1029/2018GL077493 (2018).

  2. Guest, J. R., Edmunds, P. J., Gates, R. D., Kuffner, I. B., Andersson, A. J., Barnes, B. B., Chollett, I., Courtney, T. A., Elahi, R., Gross, K., Lenz, E. A., Mitarai, S., Mumby, P. J., Nelson, H. R., Parker, B. A., Putnam, H. M., Rogers, C. S., Toth, L. T. A framework for identifying and characterising coral reef “oases” against a backdrop of degradation. Journal of Applied Ecology, doi:doi: 10.1111/1365-2664.13179 (2018).

  3. Sato, K. N., Andersson, A. J., Day, J. M. D., Taylor, J. R. A., Frank, M. B., Jung, JY, McKittrick, J., Levin, L. A. Response of Sea Urchin Fitness Traits to Environmental Gradients Across the Southern California Oxygen Minimum Zone. Frontiers in Marine Science, doi:doi: 10.3389/fmars.2018.00258 (2018).

  4. Brisbin, M. M., Mesrop, L. Y., Grossmann, M. M., Mitarai, S. Intra-host Symbiont Diversity and Extended Symbiont Maintenance in Photosymbiotic Acantharea (Clade F). Frontiers in Microbiology,  doi:doi: 10.3389/fmicb.2018.01998 (2018).

  5. Edmunds, P. J., McIlroy, S. E., Adjeroud, M., Ang, P., Bergman, J.L., Carpenter, R. C., Coffroth, M. A., Fujimura, A. G., Hench, J. L., Holbrook, S. J., Leichter, J. J., Muko, S., Nakajima, Y., Nakamura, M., Paris, C. B., Schmitt, R. J., Sutthacheep, M., Toonen, R. J., Sakai, K., Suzuki, G., Washburn, L., Wyatt, A. S. J., Mitarai, S. Critical Information Gaps Impeding Understanding of the Role of Larval Connectivity Among Coral Reef Islands in an Era of Global Change, Frontiers in Marine Science, doi:doi: 10.3389/fmars.2018.00290 (2018).

  6. Le Gal, M., Violeau, D., Ata, R., Wang, X. Shallow water numerical models for the 1947 gisborne and 2011 Tohoku-Oki tsunamis with kinematic seismic generation. Coastal Engineering, doi:doi: 10.1016/j.coastaleng.2018.04.022 (2018).

  7. Nakajima, Y., Chuang, PS., Ueda, N., Mitarai, S. First evidence of asexual recruitment of Pocillopora acuta in Okinawa Island using genotypic identification. PeerJ, doi:doi: 10.7717/peerj.5915 (2018).

  8. Gavelis, G. S., Herranz, M., Wakeman, K. C., Ripken, C., Mitarai, S., Gile, G. H., Keeling, P. J., Leander, B. S. Dinoflagellate nucleus contains an extensive endomembrane network, the nuclear net. Scientific Reports, doi:doi: 10.1038/s41598-018-37065-w (2019).

  9. Brisbin, M. M. Differential Gene Expression Supports a Resource-Intensive, Defensive Role for Colony Production in the Bloom-Forming Haptophyte, Phaeocystis globosa. Journal of Eukaryotic Microbiology, doi:doi: 10.1111/jeu.12727 (2019).

4.2 Books and other one-time publications

Nothing to report

4.3 Oral and Poster Presentations

  1. Brisbin, M. M., Mitarai, S. Differential gene expression associated with colony formation in the bloom-forming Haptophyte Phaeocystis globosa, 2018 PSA/ISOP Annual Meeting, Vancouver, Canada, 2018.08.01 (2018).

  2. Ares Pita, A., Nunoura, T., Sakai, S., Hasegawa, Y., Iinuma, Y., Sasaki, T., Mitarai, S. Response of Deep-sea hydrothermal vent Epsilonproteobacteria Sulfurovum sp. NBC37-1 and Nitratiruptor sp. SB155-2 to heavy metals, 15th Deep-Sea Biology Symposium, Monterey, USA, 2018.09.11 (2018).

  3. Sato, K. N., Andersson, A. J., Day, J. M. D., Taylor, J. R. A., Frank, M. B., Jung, JY., McKittrick, J., Levin, L. A. Response of Sea Urchin Fitness Traits to Environmental Gradients Across the Southern California Oxygen Minimum Zone, 15th Deep-Sea Biology Symposium, Monterey, 
    USA. 2018.09.11 (2018).

  4. Mitarai, S., Sato, K. N., Shchepetkin, S., McWilliams, J. C., Mullineaux, L. S., Levin, L. A. Climate Change Effects on Dispersal from the Western Pacific Hydrothermal Vents, 15th Deep Sea Biology Symposium, Monterey, USA, 2018.09.13 (2018).

  5. Nakajima, Y., Nakamura, M., Watanabe, H. K., Mitarai, S. Larval dispersal contributes to genetic diversity and connectivity of limpet (Lepetodrilus nux) populations in the Okinawa Trough, 15th Deep-Sea Biology Symposium. Monterey, USA, 2018.09.13 (2018).

  6. Thomas, M.K. Behind the single-use culture, TEDxOIST 2018, Okinawa, Japan, 2018.10.13 (2018).

  7. Brisbin, M. Mars, Sato, K. N., Ares Pita, A., Mitarai, S. Investigating the effect of red soil runoff events on plankton community composition in Okinawa, Japan, IFCBWorks18, Woods Hole, USA, 2018.11.15 (2018).

  8. Mitarai, S. Formulation for an oceanographic observation system in Okinawa, The 3rd Marine Okinawa Science Work Shop, Okinawa, Japan, 2018.11.19 (2018).

  9. Thomas, M.K., Nakajima, Y., Mitarai, S. Landscape genetic method to explain intra- and inter-island propagule transport of mangrove species, The 3rd Marine Okinawa Science Work Shop. Okinawa, Japan, 2018.11.19 (2018).

  10. Nakajima, Yuichi, Chuang, Po-Shun, Mitarai, Satoshi. The reproductive characteristics of Pocillopora acuta kept in an outdoor tank. The 3rd Marine Okinawa Science Work Shop, Okinawa, Japan. 2018.11.19 (2018).

  11. Nakajima, Y., Chuang, PS., Mitarai, S. The reproductive characteristics of Pocillopora acuta kept in an outdoor tank, The 21st Annual Conference of the Japanese Coral Reef Society, Okinawa, Japan, 2018.11.22-11.25 (2018).

  12. Mitarai, S., Nakajima, Y., Sato, K. N. Biophysical Modeling & Observations Of Okinawan Coral Reefs, 100 Island Challenge: Cross-regional perspectives of coral reef structure and function. OIST Seaside House, Okinawa, Japan, 2019.01.15-01.17 (2019). 

  13. Ares Pita, A., Sato, K. N., Brisbin, M. M., Diaz, J., Ripken, C., Mitarai, S. Plankton community structure dynamics under Red Soil Pollution within coral reef ecosystems, ASLO 2019: Aquatic Science Meeting, San Juan, Puerto Rico, 2019.02.26 (2019).

  14. Brisbin, M. M. WikiProject Limnology & Oceanography: Curating Open Aquatic Knowledge, ASLO 2019: Aquatic Science Meeting, San Juan, Puerto Rico, 2019.02.27 (2019).

  15. Le Gal, M., Mitarai, S. Modelling Mangrove propagule dispersion aroung Baja California Gulf through numerical hydrodynamic model, ASLO 2019: Aquatic Sciences Meeting, San Juan, Puerto Rico, 2019.02.28 (2019).

  16. Brisbin, M. M., Mitarai, S. Complementing high-throughput sequencing with high-throughput imaging to illuminate abundance and life history of photosymbiotic acantharians, ASLO 2019: Aquatic Sciences Meeting, San Juan, Puerto Rico, 2019.02.28 (2019).

  17. Nakajima, Y., Wepfer, P. H., Mitarai, S. The local genetic structure of Galaxea coral populations in the Ryukyu Archipelago, The 66th Annual Meeting of the Ecological Society of Japan, Kobe, Japan, 2019.03.18 (2019).

5. Intellectual Property Rights and Other Specific Achievements

Nothing to report

6. Meetings and Events

6.1 100 Island Challenge: Cross-regional perspectives of coral reef structure and function, OIST Jointly-Funded Workshop

  • Date: January 15-17, 2019
  • Venue: OIST Seaside House
  • Speakers:
    • Rusty Brainard  (Graduate Affiliate Faculty, University of Hawaii <<participating remotely>>)
    • Andy Estep (Waitt Institute)
    • Will Figueira (University of Sydney)
    • Atsushi Fujimura (University of Guam)
    • Jamison Gove  <<participating remotely>>
    • Melanie McField (Smithsonian Institution)
    • Satoshi Mitarai (OIST)
    • Masako Nakamura (Tokai University)
    • Serge Planes (CRIOBE)
    • James Reimer (University of the Ryukyus)
    • Randi Rotjan (Boston University <<participating remotely>>)
    • Stuart Sandin (SIO / UC San Diego)
    • Jennifer Smith (SIO / UC San Diego <<participating remotely>>)
    • Brian Zgliczynski (SIO / UC San Diego)

6.2  Diving Emergency Management Provider Program (Divers Alert Network)

  • Date: July 18,19 & October 23, 25, 2018
  • Funding: provided by the Shohei Suzuki Research Safety Fund to Sato, K. and Mitarai, S.

7. Other

Nothing to report.