Ryuta Terada

Ryuta Terada
Kagoshima University | Kadai · United Graduate School of Agricultural Sciences

PhD
No algae, no life...

About

171
Publications
28,261
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Introduction
Born in Kumamoto and raised in Sapporo, Hokkaido, Japan, he studied at the Department of Biology and Aquaculture, Hokkaido University (PhD. in Fisheries Science in 1999). Since then, he has been studying macroalgae at Kagoshima University for more than 20 years. His research is particularly focused on the diversity and ecophysiology of macroalgae, in relation to climate change and degradation of the coastal ecosystem. He also has experience in field surveys using SCUBA more than 2000 times.
Featured research
Article
Full-text available
The important role of vegetated ecosystems in the sequestration of carbon has gained strong interest across a wide variety of disciplines. With evidence growing of the potential for macroalgae ecosystems to capture carbon, there is burgeoning interest in applying newfound knowledge of carbon capture rates to better understand the potential for carbon sequestration. Seaweed farms are expected to play a significant role in carbon capture; advocates for the expansion of seaweed farms are increasing in many countries. In general, seaweed farms are expected to be highly productive, although whether they are autotrophic or heterotrophic ecosystems and hence potential exporters of carbon, is under debate. Therefore, we present our investigation of three seaweed farms, two in northern Japan and one in southern Japan. We examine the frequency of autotrophic days and compare potential rates of carbon capture of the seaweed farms with two natural macroalgae ecosystems and one degraded site. We estimated potential carbon capture rates by calculating the net ecosystem productivity from continuous recordings of dissolved oxygen concentrations under natural environmental conditions. The net ecosystem production rates for the natural ecosystems in Arikawa Bay and Omura Bay were equivalent to 0.043 and 0.054 [g C m-2 d-1] m-1, respectively. Whereas, for the degraded ecosystem in Tainoura Bay, it was -0.01 [g C m-2 d-1] m-1. We reveal that the Undaria pinnatifida farm in Matsushima Bay experience autotrophy more often than natural ecosystems, although for seaweed farms producing U. pinnatifida in Hirota Bay and Cladospihon okamuranus at Bise Point, autotrophy was less frequently observed. Nevertheless, up to 14.1 g C m-2 (0.110 g C m-2 d-1) was captured by the production of U. pinnatifida and 3.6 g C m-2 (0.034 g C m-2 d-1) was captured by C. okamuranus, and the total yield of carbon captured during 2021 production season for these farms was 43,385 kg C.
Article
Full-text available
We determined the chronic effects of dehydration on the photochemical efficiency of a cultivated brown alga, Undaria pinnatifida (Alariaceae, Laminariales), in young sporophytes as cultivated sporelings. The effective quantum yields of photosystem II (ΔF/Fm′) at 50% humidity decreased markedly after 20 min of emersion and dropped almost zero after 60 min of emersion; the values did not restore even after subsequent 1-day immersion. The decreasing values coincided with a decrease in absolute water content of less than 40%. However, under 99% humidity up to 5-day emersion, the ΔF/Fm′ well remained and the last state exhibited a similar level to the initial value after a 48-h emersion at 20 °C and after 72 h of emersion at 10 °C, suggesting that the thalli were not truly dehydrated under saturated humidity and that photosynthetic activity was maintained for several days even without immersion in seawater. In addition, the subsequent growth of young sporophytes exposed to transportation storage stress featuring (1) immersed in seawater with aeration (ST1), (2) those without aeration (ST2), and (3) wrapped in paper towels moistened with seawater (ST3) revealed that the sporophytes exposed at lower temperature exhibited a higher subsequent growth than those at a higher temperature. The subsequent growth of ST3 was lower than ST1; however, the values of ST3 were higher than those of ST2 more than 12 °C, associating with poor seawater quality without aeration. These results indicated that the maintenance of moisture in the alga at low temperatures might be essential for the transportation of the sporelings.
Article
Full-text available
The combined effects of temperature and irradiance and the influences of desiccation and salinity on the photochemical efficiency in a subtropical red alga, Phycocalidia tanegashimensis (= Pyropia tanegashimensis, Bangiaceae) from Tanegashima Island, Japan, were determined to reveal how this species has adapted to its habitat in the splash zone. Continuous 6-h exposure to irradiance of 200 (low) and 1000 (high) µmol photons m⁻² s⁻¹ at 12, 20, and 28 °C showed a decline in the effective quantum yields (ΔF/Fm′) of photosystem II (PSII) during the exposures; nevertheless, the maximum quantum yields (Fv/Fm) of PSII measured in subsequent 14-h dim-light acclimation almost returned to initial values at 20 and 28 °C, revealing its high capacity to recovery. In contrast, those under both low and high irradiances at 12 °C did not recover to initial values even after 14-h dim-light acclimation, signifying enhanced inhibition under irradiance at low temperature. The response to continuous desiccation (~ 480 min) under 50% humidity at 24 °C showed that the ΔF/Fm′ decreased with decreasing absolute water content (AWC). However, for the samples with an AWC above 10%, ΔF/Fm′ mostly recovered to initial levels after subsequent 1-day rehydration in seawater, suggesting relatively strong tolerance to desiccation. This alga also tolerated a broad range of salinity (i.e., 10–60 psu) under 3-day exposures. The adaptations of P. tanegashimensis to relatively high irradiance, warm temperature, and a strong osmotic (desiccation and salinity) tolerance may explain its high capacity to flourish in the splash zone in the subtropical environment of Japan.
Additional affiliations
April 2020 - present
Kagoshima University
Position
  • Head of Faculty
April 2016 - present
Kagoshima University
Position
  • Professor (Full)
February 2004 - January 2005
University of Hawaii, Manoa
Position
  • Researcher
Education
April 1995 - March 1999
Hokkaido University
Field of study
  • Fisheries Science
April 1993 - March 1995
Hokkaido University
Field of study
  • Fisheries Science
April 1989 - March 1993
Hokkaido University
Field of study
  • Fisheries Science

Publications

Publications (171)
Article
The responses of photochemical efficiency to desiccation and salinity gradients in an intertidal edible brown macroalga, Sargassum fusiforme (Harvey) Setchell (Sargassaceae, Fucales), were determined using a pulse amplitude modulation (PAM)‐chlorophyll fluorometer. The effective quantum yields (ΔF/Fm'; = ΦPSII) of photosystem II (PSII) dropped to z...
Article
Full-text available
The important role of vegetated ecosystems in the sequestration of carbon has gained strong interest across a wide variety of disciplines. With evidence growing of the potential for macroalgae ecosystems to capture carbon, there is burgeoning interest in applying newfound knowledge of carbon capture rates to better understand the potential for carb...
Article
We determined the response of photochemical efficiency to desiccation and salinity in an edible brown alga, Saccharina japonica (var. japonica), using a pulse amplitude modulation chlorophyll fluorometer. Natural populations of this species in Muroran, Hokkaido, Japan are most of the time immersed in the subtidal zone; however, those at the uppermo...
Article
Domoic acid (DA), the causative agent of amnesic shellfish poisoning, is produced by select organisms within two distantly related algal clades: planktonic diatoms and red macroalgae. The biosynthetic pathway to isodomoic acid A was recently solved in the harmful algal bloom-forming diatom Pseudonitzschia multiseries, establishing the genetic basis...
Article
Full-text available
We determined the chronic effects of dehydration on the photochemical efficiency of a cultivated brown alga, Undaria pinnatifida (Alariaceae, Laminariales), in young sporophytes as cultivated sporelings. The effective quantum yields of photosystem II (ΔF/Fm′) at 50% humidity decreased markedly after 20 min of emersion and dropped almost zero after...
Article
The phenology and environmental characteristics of two brown algae, Sargassum hemiphyllum and S. glaucescens (Fucales) were investigated at Yamagawa, Ibusuki, Kagoshima Bay, Japan. Their vertical distributions in the upper subtidal zone were determined using the line transect method. The two species were found on the rocks and cobbles at a depth of...
Article
Ecklonia radicosa (Laminariales), a canopy-forming brown alga, was reported to have disappeared since 2016 at a site surveyed under a nationwide long-term monitoring survey for the natural ecosystem (Monitoring Site 1000, Japanese Ministry of Environment) in Nagashima Island, Kagoshima Prefecture, Japan. The distribution of seaweed assemblages alon...
Article
We collected the deep-water species Rhodymenia prostrata (Rhodymeniaceae, Rhodophyta), for the first time in nearly 50 years, from the type locality off Mageshima Island, Japan. Our combined rbcL, cox1 and 28S rDNA analyses suggested that R. prostrata belongs in the genus Halopeltis but is distinct from all other Halopeltis species. However, the bi...
Article
Full-text available
The combined effects of temperature and irradiance and the influences of desiccation and salinity on the photochemical efficiency in a subtropical red alga, Phycocalidia tanegashimensis (= Pyropia tanegashimensis, Bangiaceae) from Tanegashima Island, Japan, were determined to reveal how this species has adapted to its habitat in the splash zone. Co...
Article
Single‐gene markers, such as the mitochondrial cox1, microsatellites, and single nucleotide polymorphisms are powerful methods to describe diversity within and among taxonomic groups and characterize phylogeographic patterns. Large repositories of publicly‐available, molecular data can be combined to generate and evaluate evolutionary hypotheses fo...
Article
Full-text available
We investigated the effects of photosynthetically active radiation (PAR) and temperature on the photosynthesis of juvenile (JS) and mature sporophytes (MS) of a temperate edible brown alga Undaria pinnatifida cultivated in northeastern Japan, using optical dissolved oxygen sensors and pulse amplitude modulation (PAM)–chlorophyll fluorometry. Photos...
Article
Domoic acid (1, DA), a member of the natural kainoid family, is a potent agonist of ionotropic glutamate receptors in the central nervous system. The chemical synthesis of DA and its derivatives requires considerable effort to establish a pyrrolidine ring containing three contiguous stereocenters. Recently, a biosynthetic cyclase for DA, DabC, was...
Article
We present a descriptive account of the dynamics of epiphytic diatoms, epifauna, and the leaf surface area of Zostera marina in a shallow water ecosystem. We hypothesized that the growth stage of the host macrophyte (i.e., leaf surface area) influenced the presence of epiflora and epifauna, as well as that the leaf surface area and epifaunal popula...
Article
Full-text available
The effects of temperature, irradiance, and desiccation on the photosynthesis of a cultivated Japanese green alga Caulerpa lentillifera (Caulerpaceae) were determined by a pulse amplitude modulation (PAM)-chlorophyll fluorometer and dissolved oxygen sensors. The photochemical efficiency in the photosystem II (F v /F m and ΔF/F m ') during the 72-h...
Article
Full-text available
We examined the effects of four stressors, irradiance, temperature, desiccation, and salinity on the photosynthesis of a red alga, Agarophyton vermiculophyllum (= Gracilaria vermiculophylla, Gracilariales, Rhodophyta) from its native distributional range in Hokkaido and Kagoshima, Japan. Photosynthesis-irradiance (P-E) curves at 8, 16, and 28°C sho...
Article
Full-text available
The effects of temperature on the photosynthesis and growth of a subtropical red alga, Phycocalidia tanegashimensis (= Pyropia tanegashimensis, Bangiaceae, Bangiales) from Tanegashima Island, Japan, were determined to better understand the ecology of the macroscopic gametophyte. Net photosynthesis–irradiance (P–E) curves, determined at 12, 20, and...
Article
Full-text available
We determined the effects of irradiance, temperature, and desiccation on the photosynthesis of a brown alga, Sargassum muticum (Fucales), from its native distributional range in Japan by using a pulse amplitude modulation (PAM)-chlorophyll fluorometer and optical dissolved oxygen sensors. Photosynthesis-irradiance curves at three temperatures (8, 2...
Article
We report two red algal species, Chondracanthus saundersii C.W. Schneider & C.E. Lane (Gigartinaceae, Gigartinales) and Schottera koreana M.S. Calderon, T.H. Seo & S.M. Boo (Phyllophoraceae, Gigartinales), from Japan for the first time based on molecular and morphological analyses. A C. saundersii specimen was collected at a depth of 35 m offshore...
Article
The chronic effect of dehydration on photochemical efficiency was determined in two heteromorphic life-history stages of a cultivated red alga, Neopyropia yezoensis f. narawaensis (=Pyropia yezoensis f. narawaensis; Bangiaceae, Bangiales) from Saga, Kyushu Island, Japan. The response to acute emersion (~1440-min) under 50% humidity was dissimilar b...
Article
A new flattened species of Gracilariopsis from Mageshima Island, Japan is recognized based on morphological and molecular analyses of rbcL and cox1 DNA sequences. We name this new species Gp. mageshimensis sp. nov. The rbcL and cox1 analyses suggest that Gp. mageshimensis belongs to the Gracilariopsis clade, and that it is distinct from other Graci...
Article
The reproductive structures, early development and carotenoid composition of Umbraulva kuaweuweu, which is a deep-water ulvacean species recently reported from Hawaii, are reported for the first time using the specimens collected by dredging at~30 m depth from Ogasawara Islands and Mageshima in southern Japan. Although Umbraulva kuaweuweu had sipho...
Article
Full-text available
The genus Meristotheca (Solieriaceae) includes fifteen currently accepted species. They are widely distributed throughout the tropics and subtropics of both hemispheres, inhabiting the intertidal and subtidal regions of rocky shores. Molecular phylogenetic studies allowed a precise understanding of the species diversity and biogeography of the genu...
Article
“Monitoring Sites 1000” – Japan's long‐term monitoring survey was established in 2003, based on the Japanese Government policy for the conservation of biodiversity. Ecological surveys have been conducted on various types of ecosystems at approximately 1000 sites in Japan for 15 years now and are planned to be carried out for 100 years. Since 2008,...
Cover Page
Characteristic underwater views of the temperate and subarctic seaweed communities in Japan. Top left: Saccharina japonica in Muroran, Hokkaido. Bottom left: Ecklonica radicosa in Satsuma-Nagashima, Kagoshima. Bottom center: Ecklonia cava subsp. kurome in Takeno, Hyogo. Right: Sargassum communities including Sargassum siliquastrum and Sargassum pat...
Article
Full-text available
This study examined the effects of temperature and irradiance on photosynthetic characteristics of the macroscopic sporophyte (SPO) and microscopic gametophyte (GAM) stages of a subarctic brown alga, Saccharina japonica var. japonica (Laminariales) from Hokkaido, Japan. In vitro measurements under short-and long-term exposures were carried out by u...
Article
Full-text available
The chronic effects of three different stressors, irradiance, temperature, and desiccation, on Photosystem II (PSII) photochemical efficiency were investigated in two heteromorphic life-history stages of a cultivated red alga, Pyropia yezoensis f. narawaensis (Bangiales) from Japan. The maximum quantum yields of PSII (F v /F m) over the range of te...
Article
Seaweed beds form a canopy affecting water flow in and around them, and therefore affect mass transport processes between the canopy and the surrounding seawater. Nutrients and physiological byproducts are transferred to and from the bulk seawater and the macroalgae surface, where they are absorbed or released. A change in the canopy structure caus...
Article
Understanding the physiological responses of kelp to environmental parameters is essential for the conservation of natural kelp beds and increased cultivation yield. We investigated the effects of photosynthe-tically active radiation (PAR) and temperature on photosynthesis of a subarctic edible brown alga, Saccharina sculpera (Laminariales), using...
Article
Global changes in climatic conditions are expected to disrupt marine ecosystems. Ocean warming is one of many concerns, since more than 90% of the Earth's warming occurs in the oceans. Macrophyte‐dominated communities recently have become the focus of climate mitigation due to their high carbon sequestration rate. Therefore, there is an urgent need...
Article
Full-text available
The temperature and light responses of photosynthesis in two freshwater red algae, Virescentia helminthosa and Sheathia arcuata (Batrachospermaceae), were determined by a pulse amplitude modulation (PAM) chlorophyll fluorometer and dissolved oxygen sensors. Net oxygenic photosynthesis-photosynthetically active radiation (PAR) models of V. helmintho...
Article
Full-text available
This study investigated the effects of different light spectral qualities and temperature on the photosynthesis and pigment content of a subtidal edible red alga, Meristotheca papulosa. Photosynthesis–irradiance (P–E) experiments were carried out under red (660 nm), blue (450 nm), green (525 nm, light-emitting diodes), and white light (visible ligh...
Article
Full-text available
Effects of seaweed deformation on photosynthesis rate and nutrient uptake rate. Jpn. J. Phycol. (Sôrui) 68: 1-8, March 10, 2020 For seaweeds with complex structures, such as the Sargassum, increasing water velocities can cause the fronds to collapse into a more streamlined shape. Such deformation makes it difficult for seawater to flow through the...
Article
Taxonomy of the little‐studied brown algal species Punctaria mageshimensis (Ectocarpales s.l.) was reexamined by molecular phylogeny and morphology. In the genetic analyses of newly collected specimens using plastid rbcL and psaA gene sequences, the specimens morphologically referable to P. mageshimensis were phylogenetically distant from Ectocarpa...
Article
We determined the effect of irradiance and temperature on the photosynthesis of two heteromorphic life‐history stages of an endangered freshwater red alga, Thorea gaudichaudii (Thoreales) by laboratory and field measurements. Net oxygenic photosynthesis–irradiance models of macroscopic and microscopic life‐history stages revealed similar low irradi...
Article
The evolutionary and population demographic history of marine red algae in East Asia is poorly understood. Here we reconstructed the phylogeographies of two upper intertidal species endemic to East Asia, Gelidiophycus divaricatus and G. freshwateri. Phylogenetic and phylogeographic inferences of 393 mitochondrial cox1, 128 plastid rbcL, and 342 nuc...
Article
The effects of irradiance, temperature, thermal‐ and chilling‐light sensitivities on the photosynthesis of a temperate alga, Sargassum macrocarpum (Fucales) were determined by a pulse amplitude modulation (PAM)‐chlorophyll fluorometer and dissolved oxygen sensors. Oxygenic photosynthesis–irradiance curves at 8, 20, and 28°C revealed that the maximu...
Article
Four kainic acid (KA, 1)-related compounds, 4-hydroxykainic acid (2), allo-4-hydroxykainic acid (3), N-dimethylallyl-l-glutamic acid (4), and N-dimethylallyl- threo-3-hydroxyglutamic acid (5), were isolated from the red alga Digenea simplex. The structures of these compounds were elucidated using spectroscopic methods. Compounds 2 and 3 are possibl...
Article
Full-text available
The combined effects of irradiance and temperature on photosystem II (PSII) photochemical efficiency were investigated in the microscopic sporophyte and macroscopic gametophyte stages of the cultivated red algae Pyropia yezoensis f. narawaensis and Pyropia tenera (Bangiales) from Kyushu Island, Japan. Continuous 12-h exposures to 10, 100, and 1000...
Article
Full-text available
The effect of photosynthetically active radiation (PAR) and temperature on the photosynthesis of a temperate Japanese edible brown alga, Cladosiphon umezakii (Chordariaceae, Ectocarpales), from Honshu Island, Japan, was determined in the heteromorphic life history stages (macroscopic and microscopic) by using pulse-amplitude modulation (PAM) fluoro...
Article
Effects of photosynthetically active radiation (PAR) and temperature on the photosynthesis of a subarctic edible brown alga, Saccharina angustata (Laminariaceae, Laminariales), from Hokkaido, Japan, were determined using a pulse amplitude modulation (PAM)–chlorophyll fluorometer and optical dissolved oxygen sensors. Photosynthesis–PAR experiments a...
Article
Understanding of the physiological responses of kelp to environmental parameters is crucial, especially in the context of environmental change that may have contributed to the decline of kelp forests all over the world. The current study presents the photosynthetic characteristics of the macroscopic sporophyte and microscopic gametophyte stages of...
Article
A new species of marine sand‐dwelling dinoflagellate, Plagiodinium ballux N. Yamada, Dawut, R. Terada & T. Horiguchi is described from a deep (36 m) seafloor off Takeshima Island, Kagoshima Prefecture, Japan in the subtropical region of the northwest Pacific. The species is thecate and superficially resembles species of Prorocentrum, but possesses...
Article
The effect of photosynthetically active radiation (PAR) and temperature on the photosynthesis of an endangered Japanese freshwater red alga, Thorea okadae (Thoreaceae, Thoreales), was determined by using pulse-amplitude modulation (PAM) fluorometry and dissolved oxygen sensors. The macroscopic life history stage (gametophyte) was observed on pebble...
Article
Full-text available
In Japan, fresh cultivated green alga, Caulerpa lentillifera (Caulerpaceae, Bryopsidales), are packed into polystyrene containers without seawater. They can stay fresh for 1 week inside the container under room temperature, suggesting a high tolerance to desiccation. This tolerance was evaluated in the present study by employing methods based on pu...
Article
Full-text available
The combined effects of photosynthetically active radiation (PAR) and temperature on the photosynthesis of a temperate Japanese brown alga, Sargassum patens (Fucales), were determined by field and laboratory measurements. Underwater measurements of the natural population of this alga in Kagoshima, Japan, revealed that the effective quantum yield (Φ...
Article
Photosynthetic responses to temperature and photosynthetically active radiation (PAR) were investigated on the heteromorphic life history stages (macroscopic and microscopic stages) of an edible Japanese brown alga, Cladosiphon okamuranus from the Ryukyu Islands. Measurements were carried out by using optical dissolved oxygen sensors and a pulse‐am...
Article
Full-text available
The interactive effects of photoinhibition and chilling stress on the photosynthesis of a freshwater red alga, Nemalionopsis tortuosa from Kagoshima, Japan. Jpn. J. Phycol. (Sôrui) 66: 1-6, March 10, 2018 The occurrence of photoinhibition caused by chilling and light stress on the photosynthetic performance of the freshwater red alga, Nemalionopsis...
Article
Photosynthetic responses to photosynthetically active radiation (PAR) and temperature were investigated in the macroscopic sporophyte (SPO) and microscopic gametophyte (GAM) stages of the brown alga Costaria costata from Hokkaido, Japan. Measurements of net photosynthesis, respiration rates and photochemical efficiency were carried out using dissol...