Bull. Natl. Mus. Nat. Sci., Ser. B, 35(1), pp. 23–40, March 22, 2009

Distribution of Zostera species in Japan. I
Zostera marina L. (Zosteraceae)
Norio Tanaka1,*, Satoshi Aida2, Shoichi Akaike3, Hiroshi Aramaki4, Takashi Chiyokubo5,
Seinen Chow6, Akihiko Fujii7, Munehiro Fujiwara8, Hitoshi Ikeuchi9, Mitsuhiro Ishii10,
Ryoko Ishikawa11, Hiroshi Ito12, Takahiro Kudo13, Daisuke Muraoka14,
Tatsuaki Nagahama15, Tomohide Nambu16, Hiroyuki Okumura17,
Akio Oshino18, Miho Saigusa19, Yasuko Shimizu20, Tsuyoshi Suwa21, Kengo Suzuki22,
Kazuya Takeda23, Norio Tanada24, Tsuyoshi Tanimoto25, Fujinori Tsuda26, Seiji Urabe27,
Kousuke Yatsuya28, Goro Yoshida29, Takashi Yoshimatsu30,
Satoshi Yoshimitsu31, Keizo Yoshimura32, Kenji Morita33 and Kenji Saitoh34
1

Department of Botany, National Museum of Nature and Science,
Amakubo 4–1–1, Tsukuba, 305–0005 Japan
2
Hiroshima Prefectural Technology Research Institute, Fisheries & Ocean Technology Center,
Hatami 6–21–1, Ondo-cho, Kure, 737–1207 Japan
3
Hokkaido Hakodate Experiment Station, Yunokawa 1–2–66, Hakodate, 042–0932 Japan
4
Saga Prefectural Government, Jonai 1–1–59, Saga, 840–8570 Japan
5
Fukushima Prefectural Fisheries Experimental Station,
Matsushita Shimokajiro 13–2, Onahama, Iwaki, 970–0316 Japan
6
National Research Institute of Fisheries Science, Coastal Fisheries and Aquaculture Division,
Fisheries Research Agency, Nagai 6–31–1, Yokosuka, 238–0316 Japan
7
Nagasaki Prefectural Institute of Fisheries, Taira, Nagasaki, 851–2213 Japan
8
Kagawa Prefectural Fisheries Experimental Station, Farming and Cultivation Section,
Yashimahigashi-machi 75–5, Takamatsu, 761–0111 Japan
9
Fukuoka Fisheries and Marine Research Center, Buzenkai Laboratory, Unoshima 76–30, Buzen, 828–0022 Japan10
Chiba Prefectural Fisheries Research Center, Hiraiso 2492, Chikura-machi, Minami Bousou, 295–0024 Japan
11
Niigata Prefectural Fisheries and Marine Research Institute, Ikarashi-sannocho 13098–8, Nishi-ku,
Niigata, 950–2141 Japan
12
Hokkaido National Fisheries Research Institute, Coastal Fisheries and Aquaculture Division,
Fisheries Research Agency, Katsurakoi, Kushiro, 085–0802 Japan
13
Kanagawa Prefectural Fisheries Technology Center, Sea-farming Technique Division,
Jogashima, Misaki, Miura, 238–0237 Japan
14
Tohoku National Fisheries Research Institute, Coastal Fisheries and Aquaculture Division,
Fisheries Research Agency, Shinhama, Shiogama, 985–0001 Japan
15
Hyogo Prefectural Technology Center for Agriculture, Forestry and Fisherries, Tajima Fisheries Technology Institute,
Sakai 1126–5, Kasumi-ku, Kami, Mikata, 669–6541 Japan
16
Yamaguchi Prefectural Fisheries Research Center, Japan Sea Research Division,
Senzaki, Ootomari, Nagato, 759–4106 Japan17
Mie Prefecture Fisheries Research Institute, Hamajima 3564–3, Shima, 517–0404 Japan18
Miyagi Prefecture Fisheries Technology Institute, Sodenohama 97–6, Ishinomaki, 986–2135 Japan
19
Miyagi Prefecture Fisheries Technology Institute, Kesennuma Fisheries Experiment Station,
Uchinuma 119, Hajikami, Kesennuma, 988–0247 Japan
20
Fisheries Experiment Station, Okayama Prefecture, Kashino 35, Setouchi, 701–4303 Japan
21
Food, Public Health and Sanitation Division Perfectural, Citizen’s Bureau, Environment and Living Department,
Wakayama Prefectural Government, Komatsubaradoori 1–1, 640–8585 Japan
22
Kyoto Institute of Oceanic and Fisheries Science, Odashukuno, Miyadu, 626–0052 Japan (Present address: Seikai
National Fisheries Research Institute Coastal Fisheries and Aquaculture Division, Fisheries Research Agency,
Taira, 1551–8, Nagasaki, 851–2213).
23
Aichi Chita Office of Agriculture, Foresty and Fisheries, Deguchi 1–36, Handa, 475–0903 Japan

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Norio Tanaka et al.
24

East District Agriculture, Forestry and Fisheries Bureau, Tokushima Prefectural Government,
Shinkura 1–67, 770–0855 Japan
25
Fisheries Research Institute Naruto Branch, Tokushima Agriculture, Forestry and Fisheries Technology Support
Center, Seto, Naruto, 771–0361 Japan
26
Hokkaido Central Experiment Station, Resources Propagation Division,
Hamanaka-cho, Yoichi, 046–8555 Japan
27
Fisheries and Fishing Port Division, Toyama Prefectural Government, Shinsogawa 1–7, 930–8501 Japan
28
Kyoto Institute of Oceanic and Fisheries Science, Odashukuno, Miyadu, 626–0052, Japan (Present address: Seikai
National Fisheries Research Institute Coastal Fisheries and Aquaculture Division, Fisheries Research Agency,
Taira 1551–8, Nagasaki 851–2213).
29
National Research Institute of Fisheries and Environment of Inland Sea, Fisheries Research Agency,
Maruishi 2–17–5, Hatsukaichi, 739–0452 Japan
30
Yamaguchi Prefectural Fisheries Research Center, Inland Sea Division, Aiofutajima, 754–0893 Japan
31
Kagoshima Prefectural Fisheries Technology and Development Center,
Iwamoto 160–10, Ibusuki, 891–0315 Japan
32
Hokkaido Mariculture Fisheries Experiment Station, Funami 1–156–3, Muroran, 051–0013 Japan
33
Department of Research and Development, Tokyo Kyuei Co., Ltd.,
Shiba-tsurugamaru 6906–10, Kawaguchi, 333–0866 Japan
34
National Research Institute of Fisheries Science, Aquatic Genomics Research Center, Fisheries Research Agency,
Fukuura, Kanazawa, 236–8648 Japan* Corresponding author: E-mail: ntanaka@kahaku.go.jp

Abstract The distribution of Zostera marina L. was assessed based on 4,782 herbarium specimens collected throughout Japan from 2004 to 2006. Six-hundred and six sites of Zostera marina
were recorded from Hokkaido Prefecture in the north to Kagoshima Prefecture in the south. The
data reveal that Z. marina primarily occurs in sheltered sites and that the species only infrequently
inhabits areas of open coastline. The water depth at collection sites ranged from 0 m to 11.1 m,with 95.6% of Z. marina collections being made at depths of up to 3 m.
Key words : Distribution, Japan, seagrass, Zostera marina, Zosteraceae.

Seagrasses are marine angiosperms that occur
in the shallow sub-tidal and intertidal zones of
costal regions from the tropics to the arctic region (Short et al., 2001). About sixty seagrass
species in 12 genera of 4 families have beenrecorded in the world (Kuo and den Hartog,
2001). Sixteen species in 8 genera and 3 families
are known from Japan (Omori, 2000). The Japanese seagrass flora is noteworthy since it contains
several endemic species, namely Zostera
asiatica, Z. caespitosa, Z. caulescence, Z. japonica, Phyllospadix iwatensis and P. japonicus(Zosteraceae), despite the fact that most seagrass
species are widespread (Short et al., 2001).
Despite the high species diversity of the Japanese seagrass flora, reports on the distribution ofseagrass species around Japan are limited. Miki
(1933, 1934) reported the distribution of seagrasses in Japan for the first time, and provided

maps showing their occurrence. However, thesedata can not be verified because voucher specimens for his descriptions have not been found.
More recently, Omori (1993) listed specimens ofJapanese Zosteraceae species excluding Z. marina and Z. japonica, contained in the major
herbaria of Japan. In his report, Omori (1993)
observed that few studies on the distribution andecology on Japanese seagrasses have been conducted, despite their potential value for the conservation and rehabitation of seagrass meadows.
The Environment Agency of Japan (1994) has
published data on the location and area of seagrass meadows around Japan, but the component
species of these meadows were not recorded andvoucher specimens were not collected. Since
then, only few studies on the distribution ofJapanese seagrasses including new locality reports, have been published (Omori, 1996; Kudoh,Distribution of Zostera marina in Japan

1999; Aioi et al., 2000; Shoji et al., 2004;
Akaike and Goda, 2006; Tanaka et al., 2006;
Yatsuya et al., 2007; Fujiwara et al., 2009; Ishikawa, 2009).
Based on a survey of over 6,000 herbarium
specimens held in the herbarium at the National
Museum of Nature and Science, Japan (TNS), we
have compiled detailed locality data of all
Zostera (Zosteraceae) species in Japan. Species
in this genus are currently the focus of a project
being conducted by the Ministry of Agriculture,
Forests and Fisheries that seeks to assess levelsof genetic diversity within seagrass species inJapan. Many of these species form the dominantcomponent of seagrass communities in temperateparts of the world. In this the first report resulting
from this survey, we present distribution data forZ. marina, widely distributed in temperate partsof the northern hemisphere, a keystone species
that is common in seagrass meadow communities
around Japan.
Materials and Methods
Surveys of Zostera marina were conducted bymaking observations from the seashore, from aship, and by snorkeling and SCUBA diving excursions. Almost the entire Japanese coastline
was surveyed from May 2004 to December 2006.
Plants with several shoots connected by rhizomes
were collected at each population confirmed in
the surveys. In addition, around thirty shoots
were collected from plants separated by over 3 m(to avoid sampling the same genet) at one-quarterof all populations for use in the population genetic analyses. These samples were stored at 80°C
prior to DNA extraction.
Voucher specimens were made for all plants;
these have been deposited in the herbarium of the
National Museum of Nature and Science, Japan(TNS). Information on habitat parameters including water depth, water temperature, transparency
and bottom sediment, were also collected andrecorded on the voucher specimen labels.

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Results and Discussion
A total of 606 sites of Zostera marina wereconfirmed in 33 Prefectures throughout Japan,
based on a total of 4,782 herbarium specimens
collected in these surveys (Table 1 and Fig. 1).
The northernmost and the southernmost populations were Souya Oomisaki, Wakkanai, Hokkaido Prefecture (45°3123, 141°5653) and Tyougamizu, Yamagawa, Kagoshima Prefecture(31°1001, 130°3553), respectively. The populations found at Kagoshima Bay (Fig. 1M) were
the southernmost in the western Pacific. In somecases, it has been demonstrated that populations
at the periphery of a plant species’ range exhibit
low genetic diversity (Arnaud-Haond et al.,2006; Beatty et al., 2008). However, because thebay is one of the most abundant sites for Z. marina in Japan, we regard this population as an important site in progressing the understanding of
the species’ population genetic structure, as wellas that of marginal populations of seagrasses
more generally. The density of collection sites
was higher in northern Miyagi Prefecture, Sado
Island (Fig. 1B), Maizuru Bay (Fig. 1F), the Seto
Inland Sea (Figs. 1H, 1I and 1J), Amakusa Islands (Fig. 1L), and Kagoshima Bay (Fig. 1M).
In contrast, collection sites were of lower density
in Southern and Eastern Hokkaido (Fig. 1A), theSea of Japan side of Northern Honsyu (Fig. 1B)
and Western Honsyu (Fig. 1A), and the Sea ofJapan side of Fukushima and Ibaraki Prefectures(Figs. 1A and 1B). Although the density of collection sites does not completely reflect that ofnatural habitats, as Tanaka et al. (2006) reported
on distribution of Z. marina in the Sagami Sea, it
nonetheless clearly reveals that Z. marina populations throughout Japan occur primarily in sheltered sites and that this species is absent or does
not form well-developed populations in areas ofopen coastline, especially those lacking sandy or
muddy sediments.
Water depths of collection sites ranged from 0
m to 11.1 m (Table 1). The frequency distributionof collection sites indicates that 29.6% of Z. marina populations were found at depths of 1.0 m to

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Norio Tanaka et al.
Table 1.

Herbarium specimens of Zostera marina deposited in National Museum of Nature and Science (TNS).

Distribution of Zostera marina in Japan
Table 1.

—(Continued)—

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Norio Tanaka et al.
Table 1.

—(Continued)—Distribution of Zostera marina in Japan
Table 1.

—(Continued)—

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Norio Tanaka et al.
Table 1.

—(Continued)—Distribution of Zostera marina in Japan
Table 1.

—(Continued)—

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Norio Tanaka et al.

Fig. 1. Distribution of Zostera marina in Japan. Numbers on the map correlate to collection numbers in Table 1.
The positions of Figs. 1A–1M are indicated on the map.

1.5 m (Fig. 2). Moreover, 62.6% of Z. marina
populations were found at depths of up to 1.5 m,
75.1% at depths of up to 2 m, and 95.6% at up to
3 m. Nakaoka and Aioi (2001) reviewed thedepth distribution of Z. marina in Japan by conducting a literature search and concluded that Z.
marina occurs mostly at depths of 1–5 m deep.
The results of the present study demonstrates that
Z. marina occurs primarily in shallower waters inJapan, at depths of up to 3 m.
Detailed distribution data on Z. marina inJapan has been presented in this paper. Information about the population genetic structuring of
Z. marina in Japan and neighboring areas (in-cluding eastern Asia and the Russian Far East),
as well as associated ecological factors, is now
required to reveal further aspects of the species’
distribution, and to facilitate the conservation
and rehabitation of Z. marina populations inJapan.
Acknowledgement
The authors thank, Stephan Gale for criticalreading of the manuscript, Yuriko Kawana, Yuki
Ando, Sho Nagata for mounting and organizing
herbarium specimens, Ikue Arase, Akihiro Dazai,
Masaaki Fukuda, Yumiko Kato, Nobuyasu

Distribution of Zostera marina in Japan

Nakabayashi, Satoshi Ohata, Norihiko Shoji,
Ryuta Terada, Yozo Wada for sampling plants,
Masahiro Notoya, Yoko Satta, Shinji Kirihara,
Hitoshi Iizumi, Masahiro Nakaoka, Shinji
Kirihara, Toshinobu Terawaki, Hiroshi Sako,
Kiyokazu Inoue, Hirofuni Kawakami for conducting the research project.
References
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Fig. 1A. Distribution of Zostera marina in Hokkaido and Aomori Prefecture. The orientation of this map inJapan as a whole is shown in Fig. 1.

Fig. 1B. Distribution of Zostera marina in northern Honshu. The orientation of this map in Japan as a whole isshown in Fig. 1.

Distribution of Zostera marina in Japan

Fig. 1C. Distribution of Zostera marina in Chiba and Kanagawa Prefecture. The orientation of this map in Japanas a whole is shown in Fig. 1.

Fig. 1D. Distribution of Zostera marina in Aichi and Mie Prefecture. The orientation of this map in Japan as awhole is shown in Fig. 1.

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Fig. 1E. Distribution of Zostera marina in Wakayama Prefecture. The orientation of this map in Japan as awhole is shown in Fig. 1.

Fig. 1F. Distribution of Zostera marina in Kyoto Prefecture. The orientation of this map in Japan as a whole isshown in Fig. 1.

Distribution of Zostera marina in Japan

Fig. 1G. Distribution of Zostera marina in Tokushima Prefecture. The orientation of this map in Japan as awhole is shown in Fig. 1.

Fig. 1H. Distribution of Zostera marina in eastern Seto Inland Sea. The orientation of this map in Japan as awhole is shown in Fig. 1.

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Fig. 1I. Distribution of Zostera marina around western Seto Inland Sea. The orientation of this map in Japan asa whole is shown in Fig. 1.

Fig. 1J. Distribution of Zostera marina in Yamaguchi Prefecture. The orientation of this map in Japan as awhole is shown in Fig. 1.

Distribution of Zostera marina in Japan

Fig. 1K. Distribution of Zostera marina in Fukuoka, Saga and Nagasaki Prefecture. The orientation of this map
in Japan as a whole is shown in Fig. 1.

Fig. 1L. Distribution of Zostera marina around Amakusa Islands. The orientation of this map in Japan as awhole is shown in Fig. 1.

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Fig. 1M. Distribution of Zostera marina in Kagoshima Bay. The orientation of this map in Japan as a whole isshown in Fig. 1.

Fig. 2.

Frequency distribution of water depths at the Zostera marina collection sites.