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Japanese Wireweed

Image Credit: GBNNSS

Status: Established

Habitat: Marine

Threat: Competes with native species


  • large brown alga
  • grows up to 16m long, forming dense floating mats on the sea surface.


  • can occur along shores on hard rock faces and eel grass beds, forming dense stands that exclude other species.


  • reduces light available to species growing underneath, slows water flow, increases sediment deposits, reduces nutrients available to native species
  • prolific growth causes drifting which clogs marinas and boat intake pipes; covers areas of eel grass which are important bird-feeding habitats.


Following the Government’s advice in relation to COVID-19, Loughs Agency has put in place a number of measures to maximise our capacity to continue to deliver our services as best we can.