Scientists from NUI Galway and Seasearch Ireland are asking divers and marina users to keep an eye out for Undaria pinnatifida, commonly known as Wakame or Japanese kelp. This species was first recorded in Belfast Lough, Northern Ireland in 2012, Wakame has subsequently been recorded at Carlingford Lough in 2014 and Kilmore Quay in Wexford in 2016.

Since then it has been recorded by Seasearch diver Frances O'Sullivan of the Dalkey Sub Aqua club recorded it in Dun Laoghaire Harbour in 2017 and by Seasearch Ireland and KelpRes divers at Greystones Harbour in 2020. Given the widespread nature of the records on the east coast, it is thought that the species is likely to occur in suitable habitats between these areas and may have spread to other areas of the coast.

Wakame can be distinguished from other kelp species found in Ireland by the undulating margins of the blade, distinctive midrib, and belt-like stipe that often has reproductive sori at the margins. The distinctive midrib in a large blade distinguishes this species from other kelp species in Irish waters (e.g. dabberlocks - Alaria esculenta -which has a distinctive midrib but thin blade).

Seasearch Ireland and the KelpRes team at NUIG are asking any marine users who see a kelp species matching the description below to send a photo to [email protected] to confirm the identification and then our colleagues from the KelpRes team in NUIG intend to collect samples of the seaweed for genetic analysis.

Undaria pinnatifida, commonly known as Wakame or Japanese kelp identification

Kathryn Schoenrock-Rossiter explains the rationale for the sampling: "Studying the genetics of invasive species is important in terms of identifying vectors for introduction and spread. For example, in the invasive freshwater Zebra mussels (Dreissena polymorpha) a study combing genetic analysis with fieldwork revealed leisure boats from the United Kingdom as the most likely source (vector) of introduction. By using genetic tools to investigate Wakame populations we can estimate whether a single introduction event or multiple have occurred and potentially determine where from (e.g. Europe)."

Rory O'Callaghan, Seasearch Ireland: "International experience with wakame would indicate it is much more likely to occur in marinas and on other man-made structures. From here it can attach to boats and be carried to other parts of the country when boats are moved. As divers, we are particularly conscious of the need for good biosecurity practices such as cleaning or drying out their boat before moving it to another location."

Seasearch is a project by the Marine Conservation Society for divers and snorkelers, who have an interest in what they're seeing underwater, want to learn more and want to help protect the marine environment around the coasts of Britain and Ireland.