Practical ecological knowledge for the temperate reader.

Zostera marina - Common eel-grass

Family: Zosteraceae [E-flora]

"Common eelgrass is a perennial (sometimes annual) aquatic rhizomatous species native to the coastlines of North America and Eurasia, where it is found in cooler waters of the North Atlantic and North Pacific; in warmer parts of its range it dies back in the summer (Wikipedia 2012). It is a species of calmer waters in the sublittoral zone (Wikipedia 2012).
Common eelgrass co-occurs with Japanese eelgrass (Zostera japonica) from BC south to Oregon, however Japanese eelgrass is found primarily in upper intertidal zones (Green and Short 2003).
Common eelgrass is a significant species in coastal waters: "Zostera marina is the dominant species in terms of biomass and habitats on the Pacific coast of North America where it grows in: the shallow waters of the continental shelf, the Gulf of California, coastal lagoons such as San Quintin, Baja California, Mexico and Izembek Lagoon, Alaska, estuaries formed by tectonic processes like San Francisco Bay, and coastal fiords similar to Puget Sound, Washington. It is found along the coast of British Columbia, including the coasts of Vancouver Island and Queen Charlotte Islands (Haida Gwaii) in sheltered bays and coves including Bamfield Harbour and Sooke River. " (Green and Short 2003)." [E-flora]


"Zostera marina is a PERENNIAL growing to 1 m (3ft 3in). It is in flower from Jun to September, and the seeds ripen from Aug to October. The flowers are monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and are pollinated by Water.
Suitable for: light (sandy) and medium (loamy) soils. Suitable pH: acid, neutral and basic (alkaline) soils and can grow in saline soils.
It cannot grow in the shade. It can grow in water." [PFAF]

Origin Status: Native [E-flora]
"General: Perennial, aquatic herb from slender rhizomes; stems annual, branching, 100-250 cm long, arising from the rhizome nodes." [IFBC-E-flora]
"Notes: Recognition of infraspecific taxa in Z. marina (Brayshaw 1985), based on leaf features, appears to be a meaningless exercise considering the plasticity of these features and the lack of research." [IFBC-E-flora]

Habitat / Range
"Sheltered subtidal flats and common along the coast; cosmopolitan, N to AK, S to CA; E North America, Greenland, Europe, E Asia, N Africa." [IFBC-E-flora]
"Fine gravel, sand or mud in the sea from low water spring tides down to depths of 4 metres[17]. It is rarely found in estuaries[17]." [PFAF] "Europe, including Britain, from Norway south and east to the Mediterranean." [PFAF]

Edible Uses

"The Saanich and Cowichan cooked the fleshy roots and leaf bases of this plant in steaming pits to flavour seal, porpoise, and deer meat (Harry, 1969)."[EthnoCoastSalish]

Other Uses

Medicinal Uses

  • Antiaging (1; X15022719);
  • Antioxidant (1; X15022719);
  • Antiseptic (1; X1755708);
  • Immunomodulator (1; X1755708);
  • Phagocytotic (1; X1755708);
  • Photoprotective (1; X15022719).[MPB-Duke]


  • Bacteria (1; X1755708);
  • Diarrhea (f; EB28:429);
  • Dropsy (f; DAA);
  • Edema (f; HOC);
  • Goiter (f; DAA;HOC);
  • Hysteria (f; DAA; HOC);
  • Infection (1; X1755708);
  • Sunburn (1; X15022719);
  • Swelling (f; HOC);
  • Wrinkle (1; X15022719).[MPB-Duke]


"Bellacoola eat plants raw with eulachon grease. Cowichan use flshy roots and leaf bases to flvor seal, porpoise, and deer meat. Hesquiat clean and eat the brownish rhizomes raw. Kwakiutl dip stems and roots in oil to eat during feasts. Nitinaht once ate the flshy, whitish rhizomes raw. Oweekeno picked and ate the leaves with attached herring spawn. Saanich used flshy roots and leaf bases to flavor deer, porpoise and seal." [MPB-Duke]

Misc Uses
Zostera has been used as cover for cultivated plants, e.g., potatoes, and as lining in ditches to conserve ice during the summer. Other Danish uses mentioned by Brondegaard include strewing material to protect against sand-drift, as manure (though Zostera was not considered well suited for this purpose), and as cattle fodder. It was also burned to extract salt from the ashes. A curious, late World War II use was as filling in bicycle tubes." [OUZM]
Large quantities of Zostera have also been collected in Germany and the Netherlands (22: 206), partly by scything (23:192); a major use was in furniture, as a cheap substitute for horse hair." [OUZM]
An old use of Zostera worth mentioning was as packaging material for the famous glass-ware from the factories of Venice; it was thus called Alga vitriariorum." [OUZM]


"Zosterin (a seagrass pectin) has antibacterial and immunomodulatory activities of therapeutic effcacy in experimental infections (X1755708)."[MPB-Duke]

Essential Oil
"The seagrass were collected along the coast of an inland sea (Aio, Yamaguchi, southern Japan). Fresh shoots were subjected to simultaneous distillation extraction (SDE) to give an essential oil with a characteristic odour. The volatile compounds in the oil were identified by comparison of Kovats indices and GC-mass spectral data with those of authentic compounds (Table 1)." [VOZM]

"The oil yield (0.7%) from the seagrass was higher than that from the mar- ine green alga, Ulva pertusa (~0.007%) [2, 6, 7]. The composition of volatile components of the seagrass oil are essentially similar to that of the algal oil. However, with the seagrass oil, nitrogen compounds, such as 1- pyrroline, 4-methylpyridine and nicotine were de- tected as characteristic components. (7Z, 10Z, 13Z)- Hexadecatrienal, (6Z,9Z, 12Z)-pentadecatrienal, n- pentadecanal, n-tetradecanal, (2E)-nonenal and (2E)- octenal, which were identified in the Ulva oil were not detected in the seagrass oil." [VOZM]

Fatty Acids
"Thus, the eelgrass species investigated differed with respect to their fatty acid com- positions: For Zostera nana the main fatty acids were identified as the 16:0, 16:1, 18:1, 18:3, and 18:4 varieties, and for Zostera marina 16:0, 18:1, 18:2, 18:3, and 20:5. The main phospholipids were phosphatidylcholine and phosphatidylethanolamine, their amounts in the two species being approximately the same." [LEZ]


"A plant of shallow sea water, it is not really suitable for normal cultivation. Fast growth, as observed for the eelgrass Zostera marina, is a counteracting strategy to avoid light limitation. The leaves of Z. marina grow up to 6 cm per day and remain uncovered for nearly one week which enables maximum photosynthetic activity (Wium-Andersen and Borum, 1980)." [Reigosa Alleleopathy]

Habitat: "At the Skokomish River delta in Puget Sound, WA, USA, the combined effects of logging and water withdrawal led to the loss of 15–19% of highly productive low intertidal surface area and a 17% loss of eelgrass (Zostera marina) habitat. This was because of a loss of sediment transport capacity in the lower river and estuary due to water diversion and increased sediment deposition from forest harvesting (Jay & Simenstad 1996)." [Northcote FF]

Pathogens: "Labyrinthula spp. were implicated as pathogens in a wasting epidemic of eelgrass (Zostera marina) at the west coast of North America in the 1930s (Young, 1943; Muehlstein et al., 1991), causing considerable disturbance to the littoral ecosystem and collateral damage to the local fisheries industry. However, although Labyrinthula spp. are still frequently associated with pieces of moribund Zostera shoots, no further epidemics seem to have occurred since."[IntrotoFun3]

Propagation "Seed - best sown as soon as it is ripe. Division." [PFAF]



  1. [BCEthno]The Ethnobotany of the Southern Kwakiutl Indians of British Columbia, NANCY CHAPMAN TURNER AND MARCUS A. M. BELL
  2. [CultPacSilverweed]Cultivating the tekkillak, the ethnoecology of Aeksem, Pacific silverweed or cinquefoil, T. Abe Lloyd, Thesis, Northland College 2002
  3. [DukePhyto] ,Accessed Feb 8, 2015
  4. [E-flora], Accessed Dec 16, 2014
  5. [EthnoCoastSalish]The Ethnobotany of the Coast Salish Indians of Vancouver Island, NANCY CHAPMAN TURNER AND MARCUS A. M. BELL
  6. [LEZ] Lipids of the eelgrasses Zostera nana and Zostera marina, Dembitskii, V. M., Chemistry of natural compounds, V.25 Issue 5, 1989
  7. [OUZM] On the uses ofZ ostera marina, Mainly in Norway., Torbjørn Aim, Economic Botany, Winter 2003, Volume 57, Issue 4, pp 640-645
  8. [PFAF], Accessed Dec 16, 2014, Nov 8, 2020
  9. [SPF] Structure and properties of fibres from sea-grass (Zostera marina), P. Davies , C. Morvan, O. Sire and C. Baley, Journal of Materials Science, 2006
  10. [VOZM] Volatiles from Zostera marina, Wataru Kawasaki, Kenji Matsui, Yoshihiko Akakabe, Noriyasu Itai, Tadahiko Kajiwara, Phytochemistry, Volume 47, Issue 1, January 1998, Pages 27–29
  12. [Wiki-KP], Accessed Jan 23, 2015


"Stem: < 3 m. Leaf: 0.5–1.5(2) m, (0.5)1–18.5 mm wide. Inflorescence: enclosed by subtending, membranous, sheath-like leaf base; staminate, pistillate flowers alternate. Pistillate flower: ovary tapered to short style.
12 species: marine waters worldwide. (Greek: from ribbon-like leaves) [Coyer et al. 2008 Ann Bot 101:73–87; Dean et al. 2008 Madroño 55:93–112] Important food source for marine animals, some aboriginal humans; Zostera asiatica Miki reported for California (Coyer et al., Dean et al.), possibly naturalized, but may not be distinct from Zostera marina." [Jepson]

Local Species;

  1. Zostera japonica - Japanese eel-grass [E-flora]
  2. Zostera marina - common eel-grass [E-flora]


Zostera japonica - Japanese eel-grass

"General: Perennial, aquatic herb from slender rhizomes; stems annual, branching, 100-300 cm long, arising from the rhizome nodes." [IFBC-E-flora]

"Habitat / Range Tidal mudfats; rare in SW BC, known only from Boundary Bay and Tsawwassen; introduced from E Asia." [IFBC-E-flora]

Synonyms: Zostera americana (Den Hartog) [E-flora]


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