Faculty Profiles - TERADA Ryuta

Papers - TERADA Ryuta

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Chiyuki Zemba, Tomotaka Takasugi, Makoto Yunokuchi, Ryuta Terada . Significant changes in the southernmost temperate canopy-forming macroalgal communities in Japan: A comparison of their status in 2024 with that a decade ago . Journal of Applied Phycology 2026.2Reviewed International journal

Ryuta Terada, Kotaro Makino, Gregory N. Nishihara . The effects of irradiance, temperature, desiccation, and salinity on the photosynthesis of the freshwater red alga Nemalionopsis shawii (Thoreales) from Japan . Algal Research95 104584 - 104584 2026.2Reviewed International journal

Ryuta Terada; Takuzo Abe; Shingo Akita; Mitsunobu Kamiya; Hiroshi Kawai; Akira Kurashima; Chikako Nagasato; Yoshihiko Sakanishi; Hiromori Shimabukuro; Haruka Suzuki; Jiro Tanaka; Shinya Uwai; Yuki Watanabe; Ryoko Ueno; Misuzu Aoki . Significant changes in seaweed community structure revealed by a nationwide long-term monitoring survey in Japan “Monitoring-Site 1000” over the past 15 years (2008–2022) . Phycological Research74 ( 1 ) 39 - 56 2026.1Reviewed International journal

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley

Significant changes in seaweed communities were identified at six sites in Japan through the long‐term monitoring program ‘ Monitoring Sites 1000 .’ This study summarizes the results of 15 years of surveys conducted from 2008 to 2022. Annual nondestructive permanent quadrat observations and line‐transect surveys, carried out perpendicular to the shoreline, were used to assess species composition, coverage, and vertical distribution. Canopy‐forming seaweeds were present at all sites from 2008 to 2015; however, Ecklonia radicosa at the Satsuma‐Nagashima site on Kyushu, facing the open ocean, suddenly disappeared in 2016 and has not recovered since. As this species currently persists only in a nearby semi‐enclosed area, monitoring continues at both the disappeared and remaining locations. Similarly, Ecklonia cava and Eisenia bicyclis at the Shimoda site in central Honshu, facing the Pacific Ocean, gradually declined after 2018 and had completely disappeared by 2022. At the Shizugawa site on the Pacific coast of northern Honshu, the upward shift of Eisenia bicyclis communities to shallower depths—caused by seafloor subsidence following the 2011 earthquake—has persisted, with no recovery at the species' former deepest distribution. Saccharina japonica at the Muroran site in Hokkaido was abundant nearshore but showed considerable interannual variation offshore. At the remaining two sites, Takeno and Awaji‐Yura, located on the coasts of the Sea of Japan and the Pacific Ocean in central Honshu, respectively, Ecklonia and Sargassum communities appeared relatively stable. Nonetheless, shifts in canopy‐forming species were frequently observed, suggesting ongoing gap dynamics driven by community succession and episodic disturbances such as typhoons and heavy rainfall. Over the 15‐year period, canopy‐forming species disappeared from two of the six sites, apparently due to direct or indirect impacts of environmental change. Even at the other four sites, persistent communities were influenced by abiotic and biotic factors, underscoring the need for continued long‐term monitoring.

DOI： 10.1111/pre.70019

Scopus

Ryuta Terada, Masahiro Suzuki, Taiju Kitayama, Yoichi Sato, Gregory N. Nishihara . The phylogenetic identity and temperature effects on the photochemical efficiency of the edible green alga “Hitoegusa” (Gayralia spp., referred to as Monostroma nitidum in Japan) from Kagoshima and Okinawa, Japan . Journal of Applied Phycology 2025.12Reviewed International journal

Taiju Kitayama; Masahiro Suzuki; Ryuta Terada . First record of Ulva kanagawae V.Carneiro, N.T.Martins & Cassano (Ulvales, Chlorophyta) from Japan . Bulletin of the National Museum of Nature and Science. Series B, Botany51 ( 4 ) 127 - 135 2025.11Reviewed

Language：English Publishing type：Research paper (bulletin of university, research institution) Publisher：national Museum of Nature and Science

A brackishwater green macroalga collected from a small watercourse along the shore of Chichijima island, Ogasawara Islands, Japan was identified as Ulva kanagawae V.Carneiro, N.T.Martins & Cassano (Ulvaceae, Ulvophyceae) using the rbcL and tufA DNA sequences. Morphology of the alga from the Chichijima Island agrees with the original description of U. kanagawae in having unique twisted spirally and coiled, compressed, narrow ribbon-like thalli (less than 2 mm in width), profuse branching in the basal region, and multiseriate apices of the branches. This species, originally described in 2023 from São Paulo, Brazil, had not previously been recorded from the Pacific region.

DOI： 10.50826/bnmnsbot.51.4_127

CiNii Research

Christophe Vieira; Shingo Akita; Masahiro Suzuki; Ryuta Terada; Takeaki Hanyuda; Satoshi Shimada; Shinya Uwai; Hiroshi Kawai . A taxonomic sudoku: Resolving the long-standing puzzle of Japanese Dictyoteae (Dictyotales, Phaeophyceae) with new records and biogeographic insights . Journal of Phycology61 ( 5 ) 1457 - 1485 2025.10Reviewed International coauthorship International journal

Ryuta Terada; Aoi Shindo; Hikari Moriyama; Narumi Shimboku; Gregory N. Nishihara . The effects of desiccation and salinity gradients in the photochemical efficiency of a mesophotic green alga, Ryuguphycus kuaweuweu (Ulvaceae) from Kagoshima, Japan . Phycological Research73 ( 4 ) 294 - 300 2025.8Reviewed International journal

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley

In mesophotic coral ecosystems (MCEs) at depths of 30–40 m, the light environment is characterized by low intensity and limited spectral quality. However, due to minimal freshwater input, salinity remains relatively stable, and there are no tidal aerial exposures. We examined the effects of desiccation and salinity gradients on the photochemical efficiency of the mesophotic green alga, Ryuguphycus kuaweuweu (Ulvaceae), collected from a depth of 35 m off Mageshima Island in the northern end of the Ryukyu Islands, Japan, to evaluate its tolerance to desiccation and salinity. A pulse‐amplitude modulation (PAM) chlorophyll fluorometer was used for the measurements. Desiccation experiments, conducted for up to 4 h of aerial exposure under 50% humidity, at 20°C, and with an irradiance of 20 μmol photons m⁻2 s⁻1, revealed that the effective quantum yields (ΔF/Fm') of photosystem II dropped rapidly, approaching nearly zero after 45 min of aerial exposure. Since the decline in ΔF/Fm' was closely related to the loss of internal water from the thallus, the ΔF/Fm' decreased once the absolute water content (AWC) fell below 50% and never recovered to initial levels, suggesting a low tolerance to desiccation. Salinity experiments, conducted over 7 days under a broad range of salinities (0–100 psu), at 20°C, and with an irradiance of 20 μmol photons m⁻2 s⁻1 under a 12‐h light/12‐h dark photoperiod, demonstrated euryhaline responses, as the ΔF/Fm' of the thallus remained stable between 10 and 60 psu. Given that this alga thrives at mesophotic depths, where it is never exposed to air, it is unlikely to flourish at intertidal depths. The euryhaline characteristics of this alga might not provide an advantage in habitats without freshwater influence; however, species of Ulvaceae, which are widely found in shallow coastal areas worldwide, including estuaries, may commonly possess this euryhaline tolerance.

DOI： 10.1111/pre.70010

Scopus

Ryuta Terada, Kotaro Makino, Gregory N. Nishihara . The photosynthetic response of the freshwater red alga Thorea okadae to environmental gradients of temperature, irradiance, desiccation, and salinity: Adaptations to its stream habitat . Journal of Applied Phycology37 ( 4 ) 2753 - 2768 2025.5Reviewed International journal

Masahiro Suzuki, Chiyuki Zemba, Ryuta Terada . Solieria latifolia sp. nov. and S. yoshidae sp. nov. (Solieriaceae, Rhodophyta) from offshore Tanegashima Island, Japan . Phycologia64 ( 2 ) 137 - 149 2025.5Reviewed International journal

Erik E. Sotka, Ryan B. Carnegie, James T. Carlton, Lucia Couceiro, Jeffrey A. Crooks, Hilary Heyford, Hikaru Endo, Masakazu Hori, Mitsunobu Kamiya, Gen Kanaya, Judith Kochmann, Kun-Seop Lee, Lauren Lees, Hannah Miller, Massa Nakaoka, Eric Pante, Jennifer L. Ruesink, Evangelina Schwind, Åsa Strand, Richard Taylo, Ryuta Terada, Martin Thiel, Takefumi Yorisue, Danielle Zacherl, Allan E. Strand . The genetic legacy of a global marine invader . Proceedings of the National Academy of Sciences of the United States of America122 ( 15 ) e2418730122 2025.4Reviewed International coauthorship International journal

Masahiro Suzuki; Ryuta Terada . DNA-based floristic survey of red algae (Rhodophyta) growing in the mesophotic coral ecosystems (MCEs) offshore of Tanegashima Island, northern Ryukyu Archipelago, Japan . PloS one20 ( 3 ) e0316067 - e0316067 2025.3Reviewed International journal

Language：English Publishing type：Research paper (scientific journal) Publisher：Public Library of Science (PLoS)

A molecular-based floristic survey of marine red algal biodiversity was conducted offshore Tanegashima Island, which is located at the northern end of mesophotic coral ecosystems (MCEs), in the Ryukyu Archipelago, Japan. This study provides the first comprehensive catalog of red algae comprising the sublittoral marine flora of offshore Tanegashima Island, Japan, and represents the first exhaustive molecular-assisted survey of red algal marine flora in Japan. Morphological and molecular analyses using plastid-encoded rbcL and mitochondrion-encoded cox1 genes revealed a total of 129 species, which included nine newly recognized species in Japan. Morphologically, 82 species were assigned to known species. Among the 82 species, 17 included cryptic species, and 25 appeared to have misapplied names. The remaining 47 species could not be identified to the species level, which indicates the necessity of a detailed reference library containing validated DNA barcodes and further taxonomic studies based on morpho-molecular analyses.

DOI： 10.1371/journal.pone.0316067

Scopus

PubMed

Ryuta Terada . Significant decline in the seaweed and seagrass communities in Kagoshima, Kyushu Island, Japan . Jeju Journal of Island Sciences2 ( 1 ) 20 - 26 2025.2Invited Reviewed International journal

Kristina M. Hill-Spanik; Hannah Rothkopf; Allan Strand; Ryan B. Carnegie; James T. Carlton; Lucia Couceiro; Jeffrey A. Crooks; Hikaru Endo; Masakazu Hori; Mitsunobu Kamiya; Gen Kanaya; Judith Kochmann; Kun-Seop Lee; Lauren Lees; Massa Nakaoka; Eric Pante; Jennifer L. Ruesink; Evangelina Schwindt; Åsa Strand; Richard Taylor; Ryuta Terada; Martin Thiel; Takefumi Yorisue; Danielle Zacherl; Erik E. Sotka . Exploring the impact of the widely introduced Pacific oyster Magallana gigas on the dispersal of Bonamia (Haplosporida): A global snapshot . Diseases of Aquatic Organisms161 39 - 46 2025.2Reviewed International coauthorship International journal

Ryuta Terada . A brown alga, Ecklonia radicosa at the southernmost distributional limit in Japan: Reconfirmation of Ecklonia radicosa from Mageshima Island, Kagoshima, the southernmost distributional limit in Japan . The Journal of Japanese Botany99 ( 4 ) 273 - 279 2024.8Reviewed

Authorship：Lead author,　Last author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Tsumura & Co

A brown alga, Ecklonia radicosa (Kjellman) Okamura (Laminariales), is one of the canopy-forming algae in the kelp forest, and it is distributed at the lowest latitude among Japanese kelp species. Although the southern distributional limit of this alga is known as Mageshima Island, Kagoshima Prefecture, its presence was believed to have disappeared from this site due to climate change, as there were no records and specimens from the site for at least the last two decades. In this study, the existence of this alga was reconﬁrmed in October 2023 at a site from a depth of 35 m offshore of Mageshima Island. This alga was ﬁrst conﬁrmed on Mageshima Island in 1948. However, the latest collection’s specimen from the site, deposited at major algal herbaria, including Kagoshima University, dates back to April 1971. Even though a long-term dredge survey was conducted more than 250 times between 2006 and 2022 using T/S Nansei-Maru, Kagoshima University, E. radicosa was not conﬁrmed. In the reconﬁrmation of this alga, the blade was greatly grazed, suggesting a browsing effect by herbivorous parrotfish; however, as the sorus was confirmed at the lower portion of the blade, maturation and alternation of generations seemed to continuously occur at the study site.

DOI： 10.51033/jjapbot.ID0211

CiNii Research

Ryuta Terada, Kyosuke Yoshizato, Kazuma Murakami, Gregory N. Nishihara . Phenology and the response of photosynthesis to irradiance and temperature gradient in the herbal drug red alga, Chondria armata (Rhodomelaceae, Ceramiales) from Kagoshima, Japan . Journal of Applied Phycology36 ( 4 ) 2139 - 2152 2024.8Reviewed International journal

Ryuta Terada; Koki Matsuda; Gregory N. Nishihara . Optimizing cultivation and shipping environments for an edible green alga, Caulerpa chemnitzia var. laetevirens (Bryopsidales) from Japan: Effects of temperature, irradiance, desiccation and salinity on photochemical efficiency . Phycological Research72 ( 2 ) 79 - 91 2024.4Reviewed International journal

Rumina Nakamura, Takuya Iwanaga, Keita Nakahara, Dai Sumiyoshi, Ryuta Terada . The effect of photochemical efficiency in cultivated Pyropia sporophytes under the conchospore-release suppression treatment resulting from postponed seeding date . Nippon Suisan Gakkaishi89 ( 6 ) 521 - 528 2023.11Reviewed

Authorship：Last author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japanese Society of Fisheries Science

This study examined the effect of photochemical efficiency (ΔF/Fm′) in cultivated sporophytes of Pyropia yezoensis f. narawaensis under the conchospore-release suppression treatment resulting from postponement of seeding date. Two types of treatment were used to preserve sporophytes: Exp#1) Preservation in a dark aquarium tank; Exp#2) Preservation with moistened fabrics, without seawater, sealed in containers. Experiments were conducted under these two treatments for 7 days at 18 and 24℃ in the dark. In Exp#1, ΔF/Fm′ gradually decreased after culturing for more than 3 days. However, at 18℃, the values almost returned to their initial levels within one day after removing the shading. Even after the shading was removed, the values had not fully recovered after culturing for 5 and 7 days at 24℃. In Exp#2, ΔF/Fm′ was well maintained throughout the 7-day culture period at 18℃. In contrast, at 24℃, the values gradually decreased as the culture duration extended; however, after rehydration in seawater with the shading removed, the values almost fully recovered. In commercial cultivation, fishermen typically conduct these treatments for a duration of up to 3 days, suggesting that physiologically, treatments within this 3-day timeframe are likely to be appropriate.

DOI： 10.2331/suisan.23-00024

Scopus

CiNii Research

Narumi Shimboku, Ryuta Terada . Seagrass bed in Kagoshima Bay: The distribution status in 2021 and long-term decline . Nippon Suisan Gakkaishi89 ( 6 ) 510 - 520 2023.11Reviewed

Authorship：Last author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japanese Society of Fisheries Science

In 2021, the current distribution status of seagrass beds in Kagoshima Bay, Kagoshima, Japan was investigated at 77 sites including four sites located outside the bay. At each site, we measured the seagrass bed area by the naked eye using scuba, snorkeling, and coastal walking and recorded the coverage for quadrats (50 cm long and wide), which were randomly placed inside the seagrass bed. In addition, we measured the water quality including temperature, salinity, and nitrogen levels at the study sites or in the laboratory. The results showed that five species of seagrass were confirmed from the 77 sites, including Zostera marina, Zostera japonica, Halophila nipponica, Halophila major, and Ruppia maritima. Of these species, the first three were found in Kagoshima Bay. However, the total area of seagrass beds in Kagoshima Bay drastically declined to 4.39 ha excluding 2.07 ha from outside of Kagoshima Bay, which was only 11.6% of the area observed in 2006 and 2.4% of the area observed in 1978. This decline is a serious concern for the conservation of seagrass beds in this region, particularly since Z. marina in Kagoshima Bay represents the southern distributional limit of this species in Japan.

DOI： 10.2331/suisan.23-00020

Scopus

CiNii Research

Ryuta Terada; Rumina Nakamura; Takuya Iwanaga; Keita Nakahara; Gregory N. Nishihara; . The real-time measurements of PSII photochemical efficiency in the microscopic sporophyte of Pyropia yezoensis f. narawaensis (Bangiaceae) reveals the low capacity of desiccation tolerance that drops within a few minutes of dehydration . Algal Research75 103283 2023.10Reviewed International journal

Ryuta Terada, Aoi Shindo, Hikari Moriyama, Narumi Shimboku, Gregory N. Nishihara . The response of photosynthesis to temperature and irradiance in a green alga, Ryuguphycus kuaweuweu (Ulvales) reveals adaptation to a subtidal environment in the northern Ryukyu Islands . Algal Research74 103189 - 103189 2023.6Reviewed International journal

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Papers - TERADA Ryuta