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.