Japanese Eelgrass
Nanozostera japonica
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Photo credit: Rybczyk
Nanozostera japonica - Japanese eelgrass, Dwarf eelgrass
Habitat:
- Marine and inter - tidal habitats
- Sand or muddy substrate
Description:
- An annual plant that spreads by rhizomes
- Stems flat and branched
- Flat leaves with 3 parallel lines and can be 30cm in length
- Leaves can be short and narrow on tidal flats or longer and wider when submerged in lagoons
- Reproduces by seed germination and vegetatively
Origin and Distribution:
- Native to Asia
- Was introduced to USA and Canada
Impacts:
- Reduces seabird foraging due to changes in habitat structure
- Changes nutrient levels of the water
How could it get here?
- Not currently present in Northern Ireland but could spread through ballast water or with other marine plants and animals
You can help by reporting any sightings: @ the Centre for Environmental Data & Recording (CEDaR) - Or via the iRecord App.
Prevent Spread
- Report all sightings
- Promote native species and biodiversity - use alternative, native plants
- Know what you are buying/growing and source native Irish seed and plants
- Do not swap plants and cuttings
- Follow control advice and watch out for hitchhikers - inspect new imported purchases for invasive pest and pathogens
- Clean equipment before moving between waterbodies
- Never collect plants from the wild
- Safe disposal of plant material and growing media
Current Legislation Position (Listed 07 August 2025): This species must not intentionally be brought into the Union; kept; bred; transported to, from or within the United Kingdom, unless for the transportation to facilities in the context of eradication; placed on the market; used or exchanged; permitted to reproduce, grown or cultivated; or released into the environment. For further queries, you can contact the Invasive Non Native Species (INNS) Team in the Northern Ireland Environment Agency on 028 9056 9558 or Email: invasivespecies@daera-ni.gov.uk.