Similarly P. G. Harrison (1976) suggested an introduction of an exotic species, but he suggested Zostera japonica instead. A study of populations of Z. americana from Boundary Bay, south of Vancouver, British Columbia revealed no obvious differences between those plants and individuals of Z. japonica and Z. noltii. A comparison of the British Columbia specimens with illustrations by C. den Hartog (1970) of both Z. japonica and Z. noltii indicated the British Columbia plants resembled more the illustrations of Z. japonica than those of Z. noltii. A discussion of possible modes of introduction noted that a brown alga, Sargassum muticum, was introduced into the North American Pacific coast area with seed oysters. Zostera japonica occurs in areas where the oysters were obtained in Japan, and oysters were packed in Zostera species during shipment. Such shipments were possibly the means by which the species was introduced into North America. Harrison’s explanation is quite plausible, and I am accepting it until further research solves the problem.
Zostera japonica is a species of aquatic plant in the Zosteraceae family.[2] It is referred to by the common names dwarf eelgrass[4] or Japanese eelgrass, and is native to the seacoast of eastern Asia from Russia to Vietnam, and introduced to the western coast of North America. It is found in the intertidal zone and the shallow subtidal, and grows on sandy, muddy and silty substrates.
It is considered native in the Russian Far East (Sakhalin, Kamchatka, Primorye, and the Kuril Islands), Japan, Korea, China, Korea, the Ryukyu Islands, Taiwan and Vietnam. It was first reported as being naturalized in British Columbia and in the US State of Washington,[5][6][7] but is now considered invasive as far south as California. It is believed to have been introduced with a shipment of Japanese oysters some time in the first half of the twentieth century.[8] This seagrass is mainly found in sheltered bays where the seabed is sand, mud or silt. It occurs in the intertidal zone and at depths down to about 3 m (10 ft).[1]
Japanese eelgrass is a small species and usually grows on the upper edge of seagrass beds, typically on mudflats exposed at low tide. The plants lose many of their leaves in the winter.[1] In Hong Kong, algae grows on the blades of this seagrass and snails in the species Clithon graze on this epiphytic growth. In a research study, where the snails were excluded from certain areas of seagrass bed, the epiphytic load increased and this had a deleterious effect on the total biomass of the seagrass, reducing the amount of photosynthesis and increasing physical damage from waves and currents. In the presence of the snails, the grass blades were kept cleaner, were less likely to break off and their total biomass was increased.[9]
On the west coast of North America, the non-native Japanese eelgrass is now found in the same habitats as the native common eelgrass (Zostera marina), growing beside it and sometimes displacing it. The habitat in which they both occur is used by economically important shellfish. Further research is needed to clarify the roles of the two species in the habitat and whether any management strategies are needed to protect the native species from the invader.[10] One difference between the two is that Z. marina undergoes microbial decomposition more slowly than does Z. japonica so that nutrients are recycled more quickly with the latter, giving alterations in both total productivity and in the structure of the decomposer community.[8]
Zostera japonica is a species of aquatic plant in the Zosteraceae family. It is referred to by the common names dwarf eelgrass or Japanese eelgrass, and is native to the seacoast of eastern Asia from Russia to Vietnam, and introduced to the western coast of North America. It is found in the intertidal zone and the shallow subtidal, and grows on sandy, muddy and silty substrates.
Zostera japonica là một loài thực vật có hoa trong họ Zosteraceae. Loài này được Asch. & Graebn. miêu tả khoa học đầu tiên năm 1907.[1]
Zostera japonica là một loài thực vật có hoa trong họ Zosteraceae. Loài này được Asch. & Graebn. miêu tả khoa học đầu tiên năm 1907.
矮大叶藻（学名：Zostera japonica）又名矮大葉藻，为大葉藻科大叶藻属下的一个种，被選為世界自然基金會的海洋十寶之一。
|access-date=中的日期值 (帮助)
|access-date=中的日期值 (帮助) 
这是一篇與植物相關的小作品。你可以通过编辑或修订扩充其内容。 Zostera nana
和名 コアマモコアマモ（小甘藻、小海藻、学名：Zostera japonica）は、アマモ科（新エングラー体系ではヒルムシロ科）アマモ属に分類される海草の一種である。浅海域に生育するが藻類ではなく種子植物（顕花植物）の仲間である。
主に温帯の沿岸域に分布するが、一部亜熱帯にも分布する。日本では北海道から本州、四国、九州、南西諸島（種子島、奄美大島、沖縄島、宮古島、石垣島、西表島）に至る全域に分布し、日本国外ではサハリン・カムチャツカ半島、中国南部、ベトナム、北アメリカ西岸等に分布する。
日本では全国的に分布する海草であるが、南西諸島においては沖縄島でごく小規模な群落が10数ヵ所確認されている一方で、種子島、奄美大島、宮古島及び石垣島では各1ヵ所でしか確認されておらず植物地理学上興味深い[1][2]。なお、西表島の分布状況は不明である[1]。
多年草の沈水植物。茎（根茎）は直径0.5-1.0mm程度で細く、砂泥中を匍匐して分岐し、いくつかの節（ふし）を付ける。節の間隔は1～3cmで、節から細かい根を出して砂泥にからみつく。また節からは葉をつける枝と花序をつける枝も出る。葉は2列に互生し、長さ10～25cm、幅0.1～1.3mmの狭線形、葉縁は全縁、明瞭な2-3本の平衡脈を持つ。葉の先端は鈍く尖り、基部には長さ1.2～6cmの葉鞘をつける。雌雄同株。花期は6月頃。花序は長さ約2cm程度の肉穂花序で鞘状苞に包まれる。雄花は花序の先端に、雌花は花序の中央につける。種子は長さ2cmの楕円形。
名前の通り近縁種のアマモに比べ小型の植物で、葉が小さく、根茎の節の間隔が狭い。
主に水深1-2m程度の浅海域の砂泥地に生育するが、一部汽水域でも生育する。また、他の海草類と比べて乾燥に強く[3]、低潮線付近まで見られ、干潮時には一部が水面から出る潮間帯でも生育することができ、ごく浅いところに小規模な藻場を形成する。当真（1999年）は河口域に繁茂する傾向があるとしている。
日本のほぼ全域に分布しており、2007年に発表された環境省レッドリストではそれまでの情報不足（DD）からランク外にはずされた。しかし地域によっては、沿岸域の埋め立てによる個体及び生育地への影響や水質汚染による生息環境の悪化などにより個体数・生育地が減少しており、本州及び四国の太平洋側、九州・沖縄地方などの県のレッドデータブックに掲載されている。
