
The siphoned feather weed (Dasysiphonia japonica) is a red seaweed native to the Northwest Pacific. The species tolerates a wide range of temperatures and can grow attached to substrates or be found as unattached drifting masses. Non-native populations exist in the Northeast Atlantic, Mediterranean Sea, and the Northwest Atlantic, where the species was first reported in 2007 in Narragansett Bay, Rhode Island. The first report in New York was from Long Island Sound in 2012. In New York, the species forms large blooms in summer and is considered a nuisance species, particularly in the Great South Bay. Research also suggests it may have ecological impacts.
Description
How to identify Siphoned Feather Weed:
Red filamentous seaweed
Bushy fronds up to 600 mm long
May grow attached to a substrate or be found as drifting masses
Positive identification requires a microscope
Habitat and Distribution
Siphoned feather weed is native to the Northwest Pacific. It can exist as floating masses or attached to substrates. The species occurs in low intertidal and subtidal habitats and tolerates a wide temperature range. Non-native populations exist in the Northeast Atlantic, the Mediterranean Sea, and the Northwest Atlantic, where it ranges from Long Island, NY, and Nova Scotia.
Spread
Siphoned feather weed was likely introduced either through shipping ballast or hull fouling.
Impacts
Siphoned feather weed can cause negative ecological and economic impacts.
Economic/Human Impacts
Siphoned feather weed fouls fishing and boating gear.
Siphoned feather weed forms large blooms; when subsequent blooms die off and decay, they release hydrogen sulfide and a foul odor like rotting eggs.
Decaying siphoned feather weed can be more than a nuisance; hydrogen sulfide emitted from decaying algae can cause lung irritation.
Ecological
Large blooms of algae followed by subsequent decay may also create hypoxic (low oxygen) and anoxic (no oxygen) conditions that can result in die-offs of marine life.
In laboratory experiments, decaying siphoned feather weed also released a biotoxin that directly caused the mortality of larval fish and bivalves.
Competition: Laboratory experiments also show that siphoned feather weed outcompetes native macroalgae, which may alter seaweed assemblages and the assemblages of marine life that depend on them.
How You Can Help
Clean, drain, and dry your watercraft and equipment thoroughly before visiting other waterbodies.
Inspect and remove debris and mud from boats, trailers, and equipment.
Dispose of all debris and bait in trash cans or at disposal stations.
Drain all water-holding compartments including live wells, bait wells, and bilge areas. If possible, visit a decontamination station and disinfect compartments with hot water (140°F) for at least 30 seconds.
Dry boats, trailers, and all equipment before use in another water body. A minimum of 5–7 days of drying time in dry, warm conditions is recommended.
Do not dump aquarium contents in any waterbodies, drainage ditches, or sewers.
Use certified bait that is non-invasive and disease free.
Learn how to identify Siphoned feather weed and report any encounters.
If you think you have found Siphoned feather weed:
DO NOT RELEASE IT ALIVE.
Take several photos of it from different angles and dispose of the specimen
Email the photos, noting where it was caught (coordinates preferred), to [email protected], OR
Submit a report through iMapInvasives
Additional Resources
National Estuarine and Marine Exotic Species Information System - information on marine and estuarine invertebrates and algae introduced to the United States - species profile for Siphoned feather weed.
Invasive Seaweed Spreading in Great South Bay- Article from Save the Great South Bay on Siphoned feather weed
The invasive red seaweed, Dasysiphonia japonica, forms harmful algal blooms: Mortality in early life stage fish and bivalves and identification of putative toxins – research paper examining the toxin released from siphoned feather weed as it decays
Coastal ocean acidification and nitrogen loading facilitate invasions of the non-indigenous red macroalga, Dasysiphonia japonica – research paper focused on the competition between native algae species and siphoned feather weed