Researcher Profile and Settings

Affiliation

• Faculty of Fisheries Sciences　Marine Bioresource and Environmental Science　Interdisciplinary Sustainability Studies

Job Title

• Assistant Professor

Research funding number

• 80828195

ORCID ID

•  https://orcid.org/0000-0003-1140-2593

J-Global ID

• 201801010805289485

Research Interests

• kelp   磯焼け   藻場   Ecklonia   沿岸生態系   海藻   分類   進化   

Research Areas

• Life sciences / Aquaculture

Educational Organization

•  Bachelor's degree program　School of Fisheries Sciences
•  Master's degree program　Graduate School of Fisheries Sciences
•  Doctoral (PhD) degree program　Graduate School of Fisheries Sciences

Academic & Professional Experience

• 2021/11 - Today Hokkaido University Faculty of Fisheries Sciences
• 2020/04 - 2021/10 Japan Society for the Promotion of Science JSPS Fellowships for Young Scientists PD
• 2018/10 - 2020/03 Kobe University Research Center for Inland Seas
• 2018/04 - 2018/09 Tokyo University of Marine Science and Technology Marine Science Post-doc fellow
• 2015/04 - 2018/03 Japan Society for the Promotion of Science

Education

• 2015/04 - 2018/03  Tokyo University of Marine Science and Technology
• 2013/04 - 2015/03  Tokyo University of Marine Science and Technology
• 2009/04 - 2013/03  Tokyo University of Marine Science and Technology

Association Memberships

• THE JAPANESE SOCIETY OF APPLIED PHYCOLOGY   THE JAPANESE SOCIETY OF PHYCOLOGY   

Research Activities

Published Papers

• Of sea, rivers and symbiosis: Diversity, systematics, biogeography and evolution of the deeply diverging florideophycean order Hildenbrandiales (Rhodophyta)

  Christophe Vieira, Cody Brooks, Shingo Akita, Myung Sook Kim, Gary W. Saunders

  Molecular Phylogenetics and Evolution 108106 - 108106 1055-7903 2024/05 [Refereed]
  
• Epizoic macroalgae attached on shells of the horned turban Turbo sazae inhabiting Nakane Reef, Jogashima Island, Kanagawa Prefecture, Japan

  Ding Yuhao, Taku Yoshiyama, Shingo Akita, Daisuke Fujita

  Japan. Jpn. J. Phycol. (Sôrui) 71 (3) 157 - 164 2023/11/10 [Refereed]
  
• Phenology of Codium cylindricum (Ulvophyceae, Bryopsidales) on the central Pacific coast of Japan

  Minoru Miyadai, Shingo Akita, Daisuke Fujita

  Botanica Marina 2022/10/26 [Refereed][Not invited]
  
• Gene expression of a canopy‐forming kelp, Eisenia bicyclis ( Laminariales, Phaeophyceae ), under high temperature stress

  Yoshino Hara, Yui Otake, Shingo Akita, Tomokazu Yamazaki, Fumio Takahashi, Shinya Yoshikawa, Satoshi Shimada

  Phycological Research 70 (4) 203 - 211 1322-0829 2022/07/13 [Refereed]
   

  To understand the high temperature stress acclimation of a canopy-forming kelp, RNA-seq analysis was performed on cultured Eisenia bicyclis (Kjellman) Setchell (Laminariales, Phaeophyceae), a major component species of kelp forests along the coast of Japan. We established a culture strain from a population at the northernmost distribution limit of this species and measured photosystem II activity in young sporophytes. We found that photosystem II activity was lower at 25°C than at 5–15°C, thus, comparative RNA-seq analysis was conducted between cultivated young thalli of E. bicyclis at 15°C and 25°C. Comparison with the expression genes revealed 277 up-regulated genes and 327 down-regulated genes at 25°C. The most up-regulated gene was 3-ketoacyl-CoA thiolase, which is related to fatty acid degradation. This enzyme has been reported to positively regulate abscisic acid (ABA) signaling in Arabidopsis thaliana (Brassicaceae). In addition, heat shock proteins, ATP synthase, NADH-dehydrogenase, and L-ascorbate peroxidase were up-regulated. The most down-regulated gene was taurine catabolism dioxygenase TauD/TfdA. Genes related to fatty acid metabolism, photosynthesis, and synthesis of cell wall components were down-regulated. These results suggest that E. bicyclis may counteract high temperature stress by up-regulating genes involved in protein stabilization, energy production and antioxidant processes. Conversely, photosynthesis and other metabolic processes may be damaged due to the inability to withstand high temperature stress.
• Phylogeography of a canopy‐forming kelp, Eisenia bicyclis (Laminariales, Phaeophyceae), based on a genome‐wide sequencing analysis

  Kanako Chimura, Shingo Akita, Takaya Iwasaki, Atsushi J. Nagano, Satoshi Shimada

  Journal of Phycology 58 (2) 318 - 329 0022-3646 2022/01/09 [Refereed]
   

  Analyses of phylogeographic patterns and genetic diversity provide fundamental information for the management and conservation of species. However, little is published about these patterns in Japanese kelp species. In this study, we conducted phylogeographic analyses of a canopy-forming kelp, Eisenia bicyclis, based on genome-wide SNPs identified by ddRAD-seq. We obtained 1,299 SNPs for 76 samples from nine localities across the distribution. STRUCTURE, NeighborNet, and discriminant analysis of principal components consistently showed high genetic differentiation among the Eastern Pacific, Central Pacific, and Sea of Japan coastal regions. Relatively strong gene flow was detected only within populations in the Eastern Pacific and in the Sea of Japan. Genetic diversity and genetic uniqueness were high in the Central Pacific and low in the Sea of Japan. These results suggest that there were at least three independent refugia corresponding to the three regions during the Last Glacial Maximum (LGM). Furthermore, relatively larger populations in the Central Pacific and smaller populations in the Sea of Japan have been maintained in the demographic history from before the LGM to the present. These phylogeographic histories were supported by an Approximate Bayesian Computation analysis. From a conservation genetics perspective, the loss of southern populations in the Central Pacific would greatly reduce the total genetic diversity of the species. Southern populations in the Sea of Japan, which have relatively low genetic diversity, may be highly vulnerable to environmental change, such as heat waves and increased feeding. Therefore, careful monitoring and conservation are needed in the two regions.
• Restoration of Ecklonia radicosa bed on a long-left concrete block dominated by Diadema sea urchins

  Shingo Akita, Hirokazu Yamada, Madoka Ito, Daisuke Fujita

  Algal Resources 14 (2) 49 - 58 2022/01 [Refereed]
  
• Providing a phylogenetic framework for trait-based analyses in brown algae: phylogenomic tree inferred from 32 nuclear protein-coding sequences

  Shingo Akita, Christophe Vieira, Takeaki Hanyuda, Florence Rousseau, Corinne Cruaud, Arnaud Couloux, Svenja Heesch, J. Mark Cock, Hiroshi Kawai

  Molecular Phylogenetics and Evolution 168 107408 - 107408 1055-7903 2022/01 [Refereed]
  
• First record of the genus Hildenbrandia (Florideophyceae: Hildenbrandiales) from French Polynesia and description of H. tahitiensis sp. nov

  Christophe Vieira, Shingo Akita, Yi Sun Kim, Satoshi Shimada, Hiroshi Kawai, Mayalen Zubia

  Journal of Asia-Pacific Biodiversity 14 (4) 607 - 612 2287-884X 2021/07 [Refereed][Not invited]
  
• Molecular evidence for naturally occurring intra- and inter-generic hybridization in the genus Ecklonia (Laminariales, Phaeophyceae)

  Shingo Akita, Keiichiro Koiwai, Tatsuya Ishikawa, Takashi Sakamoto, Taku Yoshimura, Setsuo Kiyomoto, Kaiji Nanri, You Tamayama-Kato, Akira Kurashima, Takeaki Hanyuda, Satoshi Shimada, Hiroshi Kawai, Daisuke Fujita

  Phycologia 60 (2) 170 - 179 0031-8884 2021/03/04 [Refereed]
   

  Reports of naturally occurring hybridization between species and genera in Laminariales are limited. Hybrids are mostly identified based on morphological evidence, which is often inadequate to distinguish hybrids from other unusual kelp morphological variants. In the present study, we found morphologically atypical Ecklonia (Ec.), which were suspected of being hybrids between Ec. radicosa (Ecr) and Ec. cava subsp. stolonifera (Eccs) (IKI 09-23) or between Ecr and Eisenia (Ei.) nipponica (Ein) (OWS 07-13), in two localities in Japan. To verify the existence of naturally occurring hybrids in Ec., we determined their maternal ancestry by mtDNA genotyping and assigned the putative hybrids to four categories (F-1, F-2 and backcross to parental species) based on microsatellite markers. The morphologically atypical specimens were defined as: F-1 generation of Ecr male x Eccs female (IKI 12, IKI 15-17 and IKI 19-22), Ecr female x Eccs male (IKI 11), or Ecr male x Ein female (OWS 07 and OWS 10-13), with relatively high posterior probabilities (>0.700). The remaining specimens were non-hybrids (Eccs: IKI 09, IKI 10 and IKI 13; Ecr: IKI 18), F-1 or backcrosses to Ecr (IKI 14, IKI 23 and OWS 08) and F-1, F-2 or backcrosses to Ecr (OWS 09). Our results provide strong genetic evidence for the existence of intra- and inter-generic hybrids of Ecklonia in the field.
• Hildenbrandia (Hildenbrandiales, Florideophyceae) from Japan and taxonomic lumping of H. jigongshanensis and H. japananensis

  Christophe Vieira, Shingo Akita, Shinya Uwai, Takeaki Hanyuda, Satoshi Shimada, Hiroshi Kawai

  Phycological Research 69 (3) 166 - 170 1322-0829 2021/02/17 [Refereed]
  
• Basic introduction of molecular phylogenetic analysis for applied phycologists

  Shingo Akita, Takeaki Hanyuda, Satoshi Shimada

  Algal resources 13 (2) 27 - 31 2020/12 [Refereed]
  
• ddRAD-seq based phytogeographic study of Gelidium elegant (Rhodophyceae) around Japanese coast

  Kanako Chimura, Takaya Iwasaki, Atushi Nagano, Shingo Akita, Satoshi Shimada

  Algal Resources 20 (13) 117 - 122 1883-3284 2020/12 [Refereed]
  
• Relationship between the amount of free amino acids and the salinity conditions in cultivation of two Neopyropia species (Rhodophyta)

  Saeri Seto, Shingo Akita, Takehiko Yokoyama, Norio Kikuchi, Satoshi Shimada

  Algal Resources 13 (2) 103 - 106 2020/12 [Refereed]
  
• High-temperature tolerance of a brown alga Eisenia Bicyclist's collected from different localities

  Yui Otake, Satoshi Shimada, Shingo Akita

  Algal Resources 13 (2) 85 - 89 2020/12 [Refereed]
  
• DNA metabarcoding analysis of macroalgal seed banks on shell surface of the limpet Niveotectura pallida

  Shingo Akita, Hiroki Murasawa, Mitsuki Kondo, Yoshihito Takano, Yoko Kawakami, Satoshi Nagai, Daisuke Fujita

  European Journal of Phycology 55 (4) 467 - 477 0967-0262 2020/10/01 [Refereed]
   

  In macroalgal restoration on urchin barren coasts, understanding the variability in microscopic stages of canopy-forming macroalgae such as kelps and fucoids is critical to reduce restoration effort (i.e. sea urchin removal). In the present study, we used epilithic macroalgae present on the limpetNiveotectura pallidato determine the macroalgal seed bank along a depth gradient of habitats (surf, turf, barren and sandy zones). We collected a total of 46 limpets in two seasons (summer: August and winter: December) and from four zones at Sashiga-hama on the north-east coast of northern Honshu, Japan. The attached organisms on the limpet shells were brushed off and identified using a plastid-encodedrbcL gene and high throughput sequencing (HTS) based DNA metabarcoding. The original data set consisted of 432 macroalgal and 224 microalgal operational taxonomic units (OTUs). For macroalgae, 37, 190 and 205 OTUs were assigned to Ulvophyceae, Phaeophyceae and Rhodophyta, respectively. For canopy-forming macroalgal OTUs, Agaraceae, Alariaceae, Lessoniaceae, Laminariaceae and Sargassaceae were detected. In summer, the OTU was significantly richest in the sandy zone (77.0 +/- 15.2 OTUs), but the difference among zones was less conspicuous in winter, ranging from 52.8 +/- 16.4 to 64.3 +/- 13.2 OTUs. The Shannon-Wiener diversity index showed similar patterns. The laminarialean and sargassacean OTUs were significantly the richest in the sandy zone during summer (p< 0.001). In light of these results, macroalgal restoration (i.e. through sea urchin removal) should be initiated in summer and the sandy zone should be preferentially targeted.
• The macroalgal culture collection in Kobe University (KU-MACC) and a comprehensive molecular phylogeny of macroalgae based on the culture strains

  Hiroshi Kawai, Takeaki Hanyuda, Shingo Akita, Shinya Uwai

  Applied Phycology 1 - 8 2020/08/06 [Refereed][Not invited]
  
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• Phenology of the edible red alga Eucheuma serra (J. Agardh) J. Agardh in northern Taiwan

  Boryuan Chen, Yang Lu, Shingo Akita, Daisuke Fujita

  Aquaculture Science 68 (2) 121 - 128 2020/07 [Refereed][Not invited]
  
• Molecular phylogeny and biogeography of Ecklonia spp. (Laminariales, Phaeophyceae) in Japan revealed taxonomic revision of E. kurome and E. stolonifera

  Shingo Akita

  Phycologia 59 (4) 330 - 339 0031-8884 2020/05/26
• Variation in “bank of microscopic forms” in urchin barren coast: detection using DNA metabarcoding based on high-throughput sequencing

  Shingo Akita, Hiroki Murasawa, Yoshihito Takano, Yoko Kawakami, Daisuke Fujita, Satoshi Nagai

  Journal of Applied Phycology 2020/05/22 [Refereed][Not invited]
  
• Finding of regeneration in a large number of wounded receptacles in Sargassum ringgoldianum (Phaeophyceae, Fucales)

  Shunro Yamano, Shingo Akita, Yuhi Hayakawa, Daisuke Fujita

  Phycological Research 68 (2) 183 - 186 2020/04 [Refereed][Not invited]
  
• A multigene molecular phylogeny of Eisenia reveals evidence for a new species, Eisenia nipponica (Laminariales), from Japan

  Kawai Hiroshi, Akita Shingo, Hashimoto Kazuki, Hanyuda Takeaki

  EUROPEAN JOURNAL OF PHYCOLOGY 55 (2) 234 - 241 0967-0262 2020/01 [Refereed][Not invited]
   

  Recently, synonymizing Eisenia with Ecklonia was suggested based on a molecular phylogeny using the rbcL gene and ITS1-5.8S rDNA sequences. However, in a multigene molecular phylogeny based on mitochondrial cox1, cox3 genes and the atp8-16S rDNA region, as well as the plastid atpB, psaA, psbA and rbcL genes, Ecklonia spp. formed a monophyletic clade supported by high statistical values, and Eisenia spp. showed monophyly depending on analytical methods. The Japanese Eisenia species that used to be identified as Eisenia arborea (E. arborea sensu Arasaki) was shown to be genetically distant from E. arborea from the NE Pacific and E. bicyclis from Japan. Eisenia spp. were morphologically distinct in having a split meristematic zone in the mature thallus forming a dorsi-ventral blade with false branches. Therefore, we propose reinstatement of Eisenia as an independent genus and describe a new species, Eisenia nipponica (= E. arborea sensu Arasaki) from Japan. E. nipponica is distributed on the Pacific Coast of central Honshu, having a separate geographic range from E. bicyclis, which is distributed on the Pacific coast of eastern Honshu and the Sea of Japan coast of north-western Honshu and northern Kyushu.
• Rapid detection of macroalgal seed bank on cobbles: application of DNA metabarcoding using next-generation sequencing

  Shingo Akita, Yoshihito Takano, Satoshi Nagai, Hisami Kuwahara, Rumiko Kajihara, Akifumi S. Tanabe, Daisuke Fujita

  Journal of Applied Phycology 31 (4) 2743 - 2753 2019/08/12 [Refereed][Not invited]
  
• Is the red alga Meristotheca papulosa annual?―Monitoring of tagged thalli at Banda, Tateyama, Central Pacific coast of Japan―

  Boryuan Chen, Shingo Akita, Akita Uehara, Daisuke Fujita

  Aquaculture Science 67 (1) 49‐56  0371-4217 2019/03 [Refereed][Not invited]
  
• Seasonal changes in taxon richness and abundance of mobile invertebrates inhabiting holdfast of annual kelp Ecklonia radicosa (Phaeophyceae, Lessoniaceae) at the central Pacific coast of Japan

  Shingo Akita, Hirokazu Yamada, Madoka Ito, Daisuke Fujita

  Phycological Research 67 51 - 58 2019/01 [Refereed][Not invited]
  
• Development of 11 Ecklonia radicosa (Phaeophyceae, Laminariales) SSRs markers using next-generation sequencing and intra-genus amplification analysis

  Shingo Akita, Keiichiro Koiwai, Takeaki Hanyuda, Syou Kato, Reiko Nozaki, Tsubasa Uchino, Takashi Sakamoto, Hidehiro Kondo, Ikuo Hirono, Daisuke Fujita

  Journal of Applied Phycology 30 (3) 2111 - 2115 1573-5176 2018/06/01 [Refereed][Not invited]
   

  Polymorphic simple sequence repeat (SSR) markers of Ecklonia radicosa were developed using Illumina MiSeq next-generation sequencing (NGS) analysis. In total, 3112 SSRs (di- to hexanucleotide motifs repeated more than six times) were identified from 61.5-Mb assembled genomic DNA using MISA perl script. Among the SSRs, di- (853 loci, 27.4%) and trinucleotides (1813 loci, 58.3%) were dominant, while tetra- (172 loci, 5.5%), penta- (175 loci, 5.6%), and hexanucleotides (99 loci, 3.2%) were not common. After specific amplification and polymorphic tests of 75 selected loci (tri- to hexanucleotide motifs repeated more than eight times), 11 SSR markers (Eradic01–11) were successfully developed. The range of the number of alleles, observed heterozygosity, and expected heterozygosity in the 11 markers was 3–13, 0.200–0.683, and 0.258–0.864, respectively. Polymorphic information content (PIC) analysis indicated that eight markers (Eradic01, 02, 04, 05, 06, 08, 09, and 11) were highly informative (PIC > 0.5) and the other three were reasonably informative (0.5 < PIC < 0.25). In addition, intra-genus amplification was obtained in all markers except for Eradic02, 08, and 11. These markers could help to reveal the genetic diversity and population structure of E. radicosa.
• Phenology of Chondracanthus tenellus (Rhodophyta) in the central Pacific coast of Honshu, Japan

  Yuhi Hayakawa, Kenta Kawata, Kazuma Machida, Shunro Yamano, Shingo Akita, Daisuke Fujita

  JOURNAL OF APPLIED PHYCOLOGY 29 (5) 2547 - 2556 0921-8971 2017/12 [Refereed][Not invited]
   

  This study reports variations in thallus size, density, and reproductive phenology in a natural population of underutilized seaweed, Chondracanthus tenellus, at Tateyama in the Pacific coast of Japan from August 2014 to October 2016. Growth was monitored by measuring the length and weight of thalli. In addition, a number of thalli fouled by spirobids, coralline, and/or fleshy epiphyte and/or grazing marks were also recorded from February 2015 to October 2016. Density was monitored by counting the number of clumps along a subtidal fixed line of 30 m long (3-4 m in depth). Reproductive efforts were evaluated by counting the number of cystocarps per thallus and carpospores per cystocarp. Average thallus length sharply dropped in October and gradually increased from November to record the maximum length (73.5 +/- 2.7 mm) in April 2016. After the season, thalli were damaged by epiphytic algae, spirobids, and bite marks with increase in temperature. It was suggested that high temperature and low nutrition in summer probably induce weakening of thallus and promote fouling by spirobids and epiphyte which accelerate depletion of C. tenellus together with herbivorous animals. Although the population showed a large gametophytic dominance, carposporic gametophytes were found in August to September and May to July with the highest value (20.6%) in September. Maturation of gametophytes probably was induced by long day length or a transition from short to long day. Number of carpospores per cystocarp was 72 +/- 15 x 103 in January. Considering the size and cleanliness of thallus, it is preferable to harvest in April.
• Use of fertilized molten slags to create Sargassum forests in subtropical shallow waters

  Daisuke Fujita, Rai Ma, Shingo Akita, Miki Kobayashi, Yuhi Hayakawa, Toshihiro Miyatani, Yuji Seki, Yasuhiro Yamahira

  JOURNAL OF APPLIED PHYCOLOGY 29 (5) 2667 - 2674 0921-8971 2017/12 [Refereed][Not invited]
   

  Recently, a solid fertilizer with condensed nutrients was manufactured using molten slag from municipal solid waste and dried cow dung. This novel substratum was used for the afforestation of Sargassum alternato-pinnatum Yamada in the subtropical Amami Ohshima Island since 2010. Seedlings were attached to discoidal, fertilized, molten slag (DFMS) blocks by hanging fertile thalli within a cage unit (4 m(3)), deployed at a depth of 4-5 m from March to April. The attached germlings grew rapidly from November and thalli of a total length of > 1 m filled the cage by the next reproductive period the following year. Water temperature varied between 17.6 and 31.9 A degrees C in 2013-2014; the water was oligotrophic (i.e., nitrogen-deficient). To measure the nutrients liberated from the DFMS blocks (28 x 5 cm; diameter x width), a batch experiment (N = 3) was undertaken using 15-L seawater plastic containers with weekly water exchange. High concentrations of NH4-N (16.3-90.0 mu mol L-1) and SiO2-Si (5.9-256.9 mu mol L-1) exuded out of the blocks for a period of 3 months and lower concentrations exuded for another 3 months, even after the block was dried for 7 months. To clarify the fertilizer effects of exudates from the DFMS blocks on algae, S. alternato-pinnatum juveniles (0.7 g) were cultured in 300-mL flasks for 1 month. The juveniles produced new leaves and increased in weight in both enriched seawater and control treatments, but the color of the thallus was darker than normal. To visualize the effects more clearly, introduction of the yellowed (nitrogen-starved) thalli of the red alga, Chondracanthus intermedius, was useful because the color of its thallus turns red under enriched conditions.
• Phlorotannin contents of Ecklonia radicosa in Hirasawa, Central Coast of Honshu, Japan : seasonal and within-thallus variations among four parts of thallus

  秋田 晋吾, 山田 博一, 伊藤 円, 藤田 大介

  藻類 = The Japanese journal of phycology 日本藻類学会 65 (2) 91 - 95 0038-1578 2017/07 [Refereed][Not invited]
  
• A New Marine Tube-Dwelling Diatom Parlibellus latirostris (Bacillariophyceae) from Japan (創刊100周年記念号)

  鈴木 秀和, 宮内 麻由美, 秋田 晋吾, 南雲 保, 田中 次郎

  植物研究雑誌 = The journal of Japanese botany ツムラ 91 (0) 355 - 363 0022-2062 2016/12 [Refereed][Not invited]
  
• Sorus formation on the holdfast haptera of the kelp Ecklonia radicosa (Phaeophyceae, Laminariales)

  Shingo Akita, Hirokazu Yamada, Madoka Ito, Michael H. Graham, Daisuke Fujita

  BOTANICA MARINA 59 (6) 433 - 438 0006-8055 2016/12 [Refereed][Not invited]
   

  Kelps usually form sori on their vegetative blades or sporophylls, and occasionally on stipes, with a notable exception being the primitive kelp Aureophycus aleuticus (Aureophycaceae), which forms sori on its discoid (haptera-free) holdfast. Here we reveal sorus formation on the holdfast (and blade and stipe) of the warm temperate annual kelp Ecklonia radicosa (Lessoniaceae), whose holdfast is formed by haptera, as is typical of the Laminariales. Surprisingly, hapteral sori continued to release zoospores until December, following blade loss in October. Such production of sori on holdfasts may be advantageous for surviving higher water temperatures and grazing pressure in warm temperate waters.
• 磯焼け対策 静岡県のガンガゼ優占域におけるガラモ場の回復と拡大―瀬切りと中層網の利用―

  山田博一, 伊藤円, 秋田晋吾, 藤田大介

  月刊海洋 47 (7) 323 - 328 0916-2011 2015/07/01 [Not refereed][Not invited]
  
• Phenology of annual kelp Eckloniopsis (Phaeophyceae, Laminariales) forest on a Diadema barren in Uchiura Bay, Central Pacific Coast of Honshu, Japan

  Shingo Akita, Hirokazu Yamada, Madoka Ito, Miki Kobayashi, Daisuke Fujita

  JOURNAL OF APPLIED PHYCOLOGY 26 (2) 1141 - 1148 0921-8971 2014/04 [Refereed][Not invited]
   

  On the southern coast of Uchiura Bay, central Pacific, Japan, Diadema barrens have expanded since the 1980s but Eckloniopsis radicosa (annual kelp endemic to Japan) has remained in deeper waters (> 10 m in depth). Phenology of the kelp was studied on isolated boulders from December 2011 for a year. Young sporophytes appeared in December and rapid growth from April brought the maximum blade length (83.3 +/- 13.9 cm) and width (56.8 +/- 12.7 cm) and standing crop (7.4 kg m(-2)) in May and June, respectively. Sorus formation began in June and spore release occurred from July to September. Blade length decreased from August and disappeared in November though holdfast remained. The unique holdfast-like spiny ball was found to provide habitats for mobile animals; its forests have an important role to maintain the biodiversity on barrens. During the period, water temperature was between 14.6 and 27.8 A degrees C, salinity was stable around 34-35 aEuro degrees, and nutrients were never depleted. Tolerance to large and frequent fluctuation of water temperature (7 A degrees C in a day), rapid growth in winter to spring, and occurrence on limited boulders in soft substrata may be the reasons for the success in the maintenance of its forest in Diadema barrens.
• Are there any top-down controls in Diadema barrens in the warm temperate Pacific coasts of Japan?

  Shingo Akita

  CAHIERS DE BIOLOGIE MARINE 54 (4) 615 - 624 0007-9723 2013 [Refereed][Not invited]
   

  Predation on the black sea urchin, Diadema, by the striped beakfish, Oplegnathus fasciatus, has been witnessed by divers. The sea urchin is also used as bait to angle the fish in Japan. Surrounding the Izu peninsula, barrens caused by a high density of Diadema are restricted to the southern coast of Uchiura Bay in the northwest of the peninsula, while O. fasciatus is limited in population size and occurs only seasonally in this region. The possibility of a top-down control on Diadema by O. fasciatus is discussed by conducting field observations and feeding experiments in tanks in parallel with a review of the spatial and temporal distribution of these species. The fish O. fasciatus, the hermit Dardanus crassimanus, and the sea star Coscinasterias acutispina were found to feed on Diadema juveniles. Among them, O. fasciatus is the only species that can voraciously consume juveniles (>80 juveniles/day by only a single fish) and prey on larger sea urchins (when their long spines are partially removed). However, predation by fish may not be critical for Diadema populations because of the cryptic nature of sea urchin recruits, their effective armor (with long spines) in adults, variations in appetite among the fishes, and the seasonality and limited size of the fish at the study site.

Conference Activities & Talks

• 函館港内第三防砂堤防における海藻相と過去の調査との比較

  秋田 晋吾, 地崎 賢汰, 古里 匡志朗, 南口 蒼太, 如澤 侑汰, 細山 裕生, 日吉 海斗

  日本藻類学会第 48 回大会  2024/03
• ドローン撮影による常磐海域漁港のコンブ群落の分布と解析手法の検討  [Not invited]

  黒丸 駿太郎, 井下 恭次, 秋田 晋吾, 藤田 大介

  日本藻類学会第 48 回大会  2024/03
• 局所スケールの遺伝的プロフィールに基づく褐藻ヒジキの再生産様式の解明

  南口 蒼太, 如澤 侑汰, 日吉 海斗, 秋田 晋吾

  日本藻類学会第 48 回大会  2024/03
• 北海道北斗市葛登支岬における紅藻ヒラムカデの形態の季節的変化

  日吉 海斗, 如澤 侑汰, 南口 蒼太, 秋田 晋吾

  日本藻類学会第 48 回大会  2024/03
• 北海道北斗市葛登支岬におけるエゾノネジモクおよびヨレモクの形態の季節変化と差異

  如澤 侑汰, 南口 蒼太, 日吉 海斗, 秋田 晋吾

  日本藻類学会第 48 回大会  2024/03
• 函館市戸井小安地先における持続的な藻場の造成と管理指標の検討

  古里 匡志朗, 川越 力, 秋田 晋吾

  日本藻類学会第 48 回大会  2024/03
• 本邦沿岸におけるマコンブの遺伝的地域性および国内移入の検出

  地崎 賢汰, 川越 力, 水田 浩之, 藤田 大介, 秋田 晋吾

  日本藻類学会第 48 回大会  2024/03
• 褐藻マコンブ配偶体の成熟誘導に関する研究

  中澤 祐人, 鶴亀 里咲, 秋田 晋吾, 鈴木 秀和, 神谷 充伸

  日本藻類学会第 48 回大会  2024/03
• 日本沿岸のコンブ目海藻と近年の藻場の衰退  [Invited]

  秋田晋吾, 古里匡志朗

  2023 年度日本付着生物学会ミニシンポジウム  2023/10
• Taxonomic study on canopy-forming laminarialean kelp species in Japan  [Invited]

  Shingo Akita

  1st Jeju International Island Symposium  2023/08
• 北斗市葛登支岬の平磯におけるヒジキ Sargassum fusiforme の集団遺伝学的研究  [Not invited]

  南口 蒼太, 地崎 賢汰, 古里 匡志郎, 前田 菜津, 羽生田 岳昭, 秋田 晋吾

  日本藻類学会第47回大会  2023/03
• 褐藻ホンダワラ類の分子系統解析

  リチャードソン 萌, 島袋 寛盛, 秋田 晋吾, 羽生 田 岳昭, 嶌田 智

  日本藻類学会第47回大会  2023/03
• ドローンを用いた常磐海域漁港におけるコンブ植生の確認

  黒丸 駿太郎, 藤田 大介, 秋田 晋吾

  日本藻類学会第47回大会  2023/03
• 函館市戸井小安地先の囲い礁におけるウニ除去に 伴う海藻植生変化とコンブ藻場回復の試み

  古里 匡志朗, 川越 力, 秋田 晋吾

  日本藻類学会第47回大会  2023/03
• マコンブ Saccharina japonica の南限個体群に着 目した系統地理学的解析

  地崎 賢汰, 川越 力, 藤田 大介, 秋田 晋吾

  日本藻類学会第47回大会  2023/03
• The optimal light conditions for egg formation in female gametophytes of Laminarialean brown algae

  鶴亀里咲, 秋田晋吾, 嶌田智

  日本生態学会大会講演要旨(Web)  2022
• 褐藻アラメの高水温耐性

  大竹佑衣, 秋田晋吾, 秋田晋吾, 嶌田智

  藻類  2022
• 褐藻アラメ属およびカジメ属の雌性配偶体の卵形成における至適光環境の共通性

  鶴亀里咲, 秋田晋吾, 秋田晋吾, 嶌田智

  藻類  2022
• 館山市坂田地先における褐藻トゲモクの季節的消長

  竹内日向子, 秋田晋吾, 秋田晋吾, 嶌田智

  藻類  2022
• 静岡県下田市志太ヶ浦におけるアラメ・カジメ藻場の長期変化,特に最近の顕著な藻場衰退について

  倉島彰, 青木優和, 秋田晋吾, 神谷充伸, 坂西芳彦, 鈴木はるか, 田中次郎, 渡邉裕基

  藻類  2022
• 褐藻の網羅的ゲノム解析プロジェクトPhaeoexplorerと32核シングルコピー遺伝子に基づく系統解析

  川井浩史, 秋田晋吾, 秋田晋吾, VIEIRA C., 羽生田岳昭, ROUSSEAU F., CRUAUD C., COULOUX A., HEESCH S., COCK J. M.

  藻類  2022
• 海中林構成種の保全に向けた基礎研究

  千村佳那子, 大竹佑衣, 秋田晋吾, 秋田晋吾, 嶌田智

  藻類  2022
• 褐藻アラメ属,カジメ属の配偶体保存株の成熟誘導

  鶴亀里咲, 秋田晋吾, 嶌田智

  日本藻類学会第45回大会  2021/03
• NBRP藻類第4期2019年度の活動紹介

  山口晴代, 鈴木重勝, 川井浩史, 羽生田岳昭, 秋田晋吾, 小亀一弘, 山口愛果, 河地正伸

  日本藻類学会第44回大会  2020
• 宮城県鳴瀬川河口域で自生していた野生ノリの緑色型自然突然変異体の種同定と生長特性  [Not invited]

  村田昂生, 秋田晋吾, 二羽恭介

  日本水産学会大会講演要旨集  2019/03
• 日本産カジメ及びその近縁種(褐藻コンブ目)の系統地理学的解析  [Not invited]

  橋本一輝, 羽生田岳昭, 秋田晋吾, 川井浩史

  藻類  2019/03
• 日本産褐藻カジメ属における種間交雑体の発見  [Not invited]

  秋田晋吾, 秋田晋吾, 羽生田岳昭, 小祝敬一郎, 近藤秀裕, 廣野育生, 坂本崇, 清本節夫, 吉村拓, 加藤葉, 石川達也, 倉島彰, 藤田大介, 川井浩史

  藻類  2019/03
• 千葉県館山市坂田地先におけるナガミルの季節的消長と成熟時期  [Not invited]

  宮代穣, 秋田晋吾, 山本敬介, 藤田大介

  藻類  2019/03
• テングサ場の異なる被度での葉上動物相の比較  [Not invited]

  山本敬介, 秋田晋吾, 秋田晋吾, 橋本友明, 宮代穣, 二羽恭介, 藤田大介

  藻類  2019/03
• 千葉県館山産アイゴの食性の季節変化  [Not invited]

  瀬戸龍太郎, 秋田晋吾, 秋田晋吾, 山本敬介, 西岡浩, 二羽恭介, 藤田大介

  藻類  2019/03
• 千葉県館山市坂田地先におけるナガミルの季節的消長と室内培養  [Not invited]

  宮代穣, 秋田晋吾, 長尾優作, 陳柏原, 藤田大介

  藻類  2018/03
• 遺伝子多様度解析を用いたアントクメ個体群の消長予測  [Not invited]

  秋田晋吾, 秋田晋吾, 小祝敬一郎, 近藤秀裕, 廣野育生, 坂本崇, 藤田大介

  藻類  2018/03
• アントクメの系統地理学的解析  [Not invited]

  秋田晋吾, 秋田晋吾, 小祝敬一郎, 羽生田岳昭, 近藤秀裕, 廣野育生, 藤田大介

  藻類  2017/03
• 千葉県館山市坂田地先における紅藻スギノリの生長と消失要因  [Not invited]

  早川雄飛, 川田健太, 町田一真, 山野旬郎, 秋田晋吾, 藤田大介

  藻類  2017/03
• 千葉県館山市坂田における紅藻トサカノリの標識藻体およびカゴ内移植藻体の観察  [Not invited]

  陳柏原, 秋田晋吾, 町田真一, 早川雄飛, 川田健太, 山野旬郎, 藤田大介

  藻類  2017/03
• 館山産オオバモクの食害の実態と再生  [Not invited]

  山野旬郎, 川田健太, 早川雄飛, 町田一真, 秋田晋吾, 藤田大介

  藻類  2017/03
• 館山産オオバモクの生殖器床の被食と再生  [Not invited]

  山野旬郎, 川田健太, 早川雄飛, 町田一真, 秋田晋吾, 藤田大介

  藻類  2016/03
• 長崎県壱岐沿岸で採集されたカジメ類の交雑体における分子同定の試み  [Not invited]

  秋田晋吾, 秋田晋吾, 小祝敬一郎, 清本節夫, 吉村拓, 近藤秀裕, 廣野育生, 藤田大介

  藻類  2016/03
• 千葉県館山市坂田地先におけるテングサ類と葉上動物の季節消長  [Not invited]

  町田一真, 川田健太, 早川雄飛, 村澤博基, 山野旬郎, 秋田晋吾, 藤田大介

  藻類  2016/03
• 千葉県館山市坂田地先の潮間帯に設けた裸地でのヒジキの季節的消長と植生の遷移  [Not invited]

  宮川椋, 秋田晋吾, 藤田大介

  藻類  2016/03
• 海産管棲珪藻Parlibellus sp.の形態と分類学的検討  [Not invited]

  鈴木秀和, 宮内麻由美, 秋田晋吾, 藤田大介, 南雲保, 田中次郎

  Diatom  2015/12
• 静岡県沼津市平沢地先で実施したガンガゼ侵入防御後のホンダワラ類の分布状況  [Not invited]

  山田博一, 伊藤円, 藤田大介, 秋田晋吾

  日本水産学会大会講演要旨集  2015/03
• GPS魚探と簡易垂下式ビデオカメラを用いた漁港・周辺藻場のモニタリング手法の検討  [Not invited]

  櫻井克聡, 桑原久実, 平野央, 秋田晋吾, 早川雄飛, 宮川椋, 藤田大介

  藻類  2015/03
• 千葉県館山市坂田地先におけるクロメの季節的消長  [Not invited]

  川田健太, 山野旬郎, 早川雄飛, 町田一真, 秋田晋吾, 藤田大介

  藻類  2015/03
• 一般廃棄物溶融スラグ活用「藻場ブロック」の藻場再生環境と栄養塩溶出能  [Not invited]

  馬蕾, 秋田晋吾, 小林美樹, 宮谷寿博, 関勇治, 山平保宏, 藤田大介

  藻類  2015/03
• 1年生大型褐藻アントクメの子嚢斑形成部位と成熟期  [Not invited]

  秋田晋吾, 山田博一, 伊藤円, 藤田大介

  藻類  2015/03
• 千葉県館山市坂田地先における大型褐藻オオバモクの成長と食害の影響  [Not invited]

  山野旬郎, 川田健太, 早川雄飛, 町田一真, 秋田晋吾, 藤田大介

  藻類  2015/03
• 沼津市平沢地先深所ブロックにおけるガンガゼ除去後の海藻植生  [Not invited]

  秋田晋吾, 山田博一, 伊藤円, 藤田大介

  藻類  2014/03
• 沼津市平沢地先における大型褐藻アントクメの季節的消長  [Not invited]

  秋田晋吾, 小林美樹, 伊藤円, 山田博一, 藤田大介

  藻類  2013/03

MISC

• Record of the endangered species Neopyropia tenera (Bangiales, Rhodophyta) at the tidal flat of Koajiro Bay, Kanagawa Prefecture

  Norio Kikuchi, Kazuhiko Yamada, Hiroaki Era, Shingo Akita, Satoshi Shimada  観音崎自然博物館研究報告 たたらはま  24-  6  -11  2020/12
• カジメ類の分類学的再検討

  秋田晋吾  海藻資源  (45)  2020
• 藻類学最前線 藻場の遺伝的多様性研究:現状と今後の展望

  秋田晋吾  藻類  66-  (3)  165‐168  2018/11  [Refereed][Invited]
  
• コンブ類の新たな分類

  秋田晋吾, 藤田大介  海藻資源  (39)  22‐23  2017/06  [Not refereed][Invited]
  
• 磯根漁業に関する研究 5 回復したガラモ場の状況調査

  山田博一, 伊藤円, 白井邦博, 藤田大介, 秋田晋吾, 佐々木昭, 飯田直樹  静岡県水産技術研究所事業報告  2014-  108  2016/03/10  [Not refereed][Not invited]
  
• 地域の海藻食材（5）アントクメ

  秋田晋吾, 藤田大介  海藻資源  34-  35  -36  2015/08  [Not refereed][Invited]
  
• 海中林復元に関する研究 1 ガラモ場生態系回復研究

  山田博一, 伊藤円, 白井邦博, 藤田大介, 秋田晋吾, 飯田直樹, 佐々木昭  静岡県水産技術研究所事業報告  2013-  95  -96  2015/06/30  [Not refereed][Not invited]
  
• 海中林復元に関する研究 1 ガラモ場生態系回復研究

  山田博一, 海野幸雄, 伊藤円, 飯沼紀雄, 白井邦博, 藤田大介, 秋田晋吾, 山田照義, 佐々木昭  静岡県水産技術研究所事業報告  2012-  98  -99  2014/03/01  [Not refereed][Not invited]
  

Awards & Honors

• 2023/03 Japanese Society of Phycology Prize for annual best paper
   

  受賞者: Yoshino Hara;Yui Otake;Shingo Akita;Tomokazu Yamazaki;Fumio Takahashi;Shinya Yoshikawa;Satoshi Shimada
• 2021/12 国際藻類学会 Tyge Christensen Prize, 2020
   Molecular phylogeny and biogeography of Ecklonia spp. (Laminariales, Phaeophyceae) in Japan revealed taxonomic revision of E. kurome and E. stolonifera 

  受賞者: Shingo Akita;Kazuki Hashimoto;Takeaki Hanyuda;Hiroshi Kawai
• 2021/03 日本藻類学会 日本藻類学会研究奨励賞
   

  受賞者: 秋田晋吾
• 2013/04 21st International Seaweed Symposium UNIVERSITAS BAKRIE GRADUATE STUDENT POSTER AWARD, 2nd Prize
   Phenology of annual kelp Eckloniopsis forest on a Diadema barren in Uchiura Bay, Central Pacific Coast of Honshu, Japan 

  受賞者: Akita Shingo;Kobayashi Miki;Yamada Hirokazu;Ito Madoka;Fujita daisuke

Research Grants & Projects

• Study on genetic diversity and ecology for southern edge population of Saccharina japonica distributing Honshu

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

  Date (from‐to) : 2022/04 -2025/03 

  Author : 藤田 大介・秋田晋吾
• 海藻ヒジキの繁殖生態の解明：有性生殖と栄養繁殖の再生産への貢献度は？

  三井住友信託銀行：ミキモト海洋生態研究助成基金

  Date (from‐to) : 2023/08 -2024/03
• Effect of genetic diversity on maintenance of macroalgal bed

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2020/04 -2023/03 

  Author : 秋田 晋吾

   

  今年度も感染症により臨海実験所の長期滞在による利用が制限されたため，実験室を主とした研究を進めることとした。前年度に単離し遺伝子型を決定したカジメの配偶体を使用して，掛け合わせる配偶体の個体数による配偶体の成熟率の違いを調べた。雄性配偶体1個体と雌性配偶体1個体と掛け合わせたものから雌雄の配偶体を4個体ずつにまで増やし，4つの実験区（♂1個体x ♀1個体，♂2個体x ♀2個体，♂3個体x ♀3個体，♂4個体x ♀4個体）を設けた。なお，実験には遺伝子型の異なる配偶体を使用し，成熟の有無については顕微鏡下で判断しやすい雌性配偶体の卵形成で評価した。雌雄の配偶体を混合した後，1週間後に卵形成の有無を各区30個体ずつ調べると，どの実験区においても卵を形成した雌性配偶体の割合は80%前後で，明確な差はないことがわかった。また，母藻による配偶体の生長速度についても調べるために，胞子体を6つ使用し，それぞれの配偶体の細胞数の変化を5日毎に計数した。その結果，どの胞子体に由来しても配偶体の細胞数は2から3個程度で，配偶体の生長速度についても親個体の違いがほとんど影響しないことがわかった。幼胞子体の生長を比較にむけて胞子体を培養している最中にあったが，就職に伴い本年度の半ばで特別研究員の資格を辞退することとなった。
• 海藻ホンダワラの被食耐性：生殖器官の再生能力の解明

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Early-Career Scientists

  Date (from‐to) : 2020/04 -2023/03 

  Author : 秋田 晋吾
• 遺伝子多様度が「海の森」の維持と形成に与える影響

  日本科学協会：笹川科学研究助成金

  Date (from‐to) : 2018/04 -2019/03 

  Author : 秋田 晋吾
• 遺伝子多様度解析を用いたアントクメ個体群消滅危険性の予測

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows

  Date (from‐to) : 2015/04 -2018/03 

  Author : 秋田 晋吾

   

  本課題では，遺伝子多様度の高い個体群が環境変異や物理的撹乱に強いことに着目し，海藻類の個体群である藻場における遺伝子多様度を解明することで，磯焼けの発生リスクが高い個体群を検出できるか調べた。平成29年度は，平成27年度に採集した個体と平成28年度に開発したマイクロサテライトマーカーを用いて，1）集団遺伝解析および2）遺伝子多様度解析を行った。 1）集団遺伝解析 平成28年度に実施した系統地理解析の結果を検証するために，11個のマイクロサテライトマーカーを用いて集団遺伝解析を行った。その結果，アントクメの遺伝集団は九州西岸と太平洋岸の2グループ，もしくは，伊豆大島，平沢，仁科，早田浦，土佐清水，串木野，長島，野母崎，新三重および原島と嫦娥崎の10グループに分かれると推定された。この結果は前年度に実施した系統地理解析を支持し，各地の個体群は遺伝的に大きく離れており，本種の分散能力は低いことが示唆された。 2）遺伝子多様度解析 各地の個体群において，検出されたアレルの数（Na: 最小の個体群に補正），ヘテロ接合度の観察値（Ho）と期待値（He），近交係数（Fis）およびアレル共有度（Psaxy）を求めた。これらの指数のうち近交係数（Fis）は，嫦娥崎，原島，新三重，野母崎，串木野，土佐清水および仁科で低く，長島，早田浦，伊豆大島および平沢で高いことが確認された。各地の生育状況から，アントクメの個体群は，拡大（嫦娥崎，原島），安定（長島，早田浦，伊豆大島および平沢）および縮小（新三重，野母崎）の3段階に分けられ，Fisと比較すると，大きな変動を示す個体群でFisが低く，Fisは個体群の現状を示す指標となり得ることが示された。

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• 2024/01 - Today   Japanese Society of Phycology   Phycological Research, Associate Editor
• 2023/04 - Today   Japanese Society of Phycologyo   Sorui associate editor