Two newly arrived seaweed species to look out for in British Channel Island waters

June 2nd, 2011 by Dr. Paul Chambers

Two non-native species of seaweed have been discovered recently on the Jersey shore.

Polyopes lancifolius was discovered for the first time at La Rocque, Jersey on 30 May 2011 and Grateloupia subpectinata was discovered in February 2011.

If you see either of these seaweed species in Channel Island waters please take a photograph, record the location, and report your discovery to Dr. Paul Chambers by email to pmc1066 @ and to the Guernsey Biological Records Centre.

Polyopes lancifolius is an invasive species from Japan that was first found in southern Brittany in 2008.  It is assumed to have been imported into France with oyster seed stock.

Polyopes lancifolius at La Rocque, Jersey (click image to expand - ©Paul Chambers)

Apparently it has not been found in European waters outside southern Brittany until now so its occurrence on the Jersey shore is a surprise.

It may have arrived in Jersey waters via the transportation of oyster stock along the French coast.

The specimen was identified by Dr Frederic Mineur, who is an expert in this species, and who has requested a sample of the Jersey specimen for a genetic study.

Polyopes lancifolius found at La Rocque in Jersey (click image to expand - ©Paul Chambers)

Polyopes lancifolius cannot be confused with any other seaweed. It is large (about 40cm), elongate and covered in thousands of soft projections that give it a furry look and feel. Photos of this specimen led one phycologist to describe it as being ‘like something out of Doctor Who’.

It would be useful to know how well-established this species is so any reports from the Channel Islands will be most welcome.

Grateloupia subpectinata on the Jersey shore (click image to expand - ©Paul Chambers)

Although Grateloupia subpectinata was discovered by Dr. Bill Farnham from Portsmouth University in September 2002 next to the Lihou Island causeway in Guernsey, it was first found at La  Collette, Jersey by Lin Baldock in February 2011.

At present Grateloupia subpectinata is common in large rock pools on Jersey’s south-east coast but its abundance might be a recent phenomenon.  It is known also from a couple of locations on England’s south coast.

Grateloupia subpectinata on the Jersey shore (click image to expand - ©Paul Chambers)

Grateloupia subpectinata is large and distinctive.  In some rock pools it appears to have taken over from Sargassum muticum, an invasive species introduced to the Channel islands in the 1970s and known locally as Japweed.

Any reports of Grateloupia subpectinata in Channel Island waters from outside of Jersey’s south-east coast would be appreciated.


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