Carpet sea squirt
Didemnum vexillum
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Photo credit: ©Julia Nunn
Habitat:
- Marine hard surfaces. The colonies have been found at water depths ranging from intertidal to continental shelf depths of 65m (213 ft).
Description:
- Exact identification of this species is very difficult and can only be undertaken by a trained expert. However, in general native species are not found in large colonies and do not form the candlewax-like dripping structures, as seen in the photographs. Please see the Habitas website on Sponges of Britain and Ireland for more info on native species.
- The invasive form can be describes as long, ropey or beard-like hanging from hard surfaces such as docks, aquaculture facilities, and ship hulls, or may be found as extensive mats covering rocky sea beds (pebbles, cobbles, boulders, and rock outcrops).
- It can reproduce from fragments and can complete a generation cycle within a week.
Origin and Distribution:
- Uncertain at present.
- The species is known from The Netherlands and France in Europe while worldwide the species is now recognised in Asia, Australasia-Pacific, Europe, and North America.
Impacts:
- Alter marine habitats.
- Interfere with fishing, aquaculture, and other coastal and offshore activities.
- Increased fouling of manmade structures such as docks, moorings, and boat hulls.
- Overgrow other organisms such seaweed, scallops, mussels, and oysters that depend on the seafloor for habitat.
- May impact on underwater archaeological sites such as ship wrecks. Produce noxious substances that deter most fish and other animals.
How did it get here?
- Uncertain at present.
- Likely vector is fouling of ocean going vessel and/or contamination of aquacultre produce.
Is it found in Northern Ireland?
- It is present in Northern Ireland. The species was recorded in Strangford Lough, County Down (NI) during October 2012.
- More distribution information can be seen on the NBN Atlas NI.
You can help by reporting any sightings: @ the Centre for Environmental Data & Recording (CEDaR) - Or via the iRecord App.
Further Resources:
- British Irish Council - Didemnum vexillum - Invasive Species Action Plan
- RAPID (Reducing and Preventing IAS Dispersal) LIFE project - Good Practice Management - Carpet Sea Squirt (Didemnum vexillum).
Prevent Spread:
- Prevent fouling of boats and equipment.
- Clean all equipment including boats before moving to new waterbodies.
- Report all sightings.
For further queries, you can contact the Invasive Non Native Species (INNS) Team in the Northern Ireland Environment Agency on 028 9056 9558 or Email: invasivespecies@daera-ni.gov.uk
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