Identification Guide. Invasive Non-Native Species in the Isle of Man

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Lizbeth Franklin
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1 Identification Guide Invasive Non-Native Species in the Isle of Man

2 What are Invasive Non-Native Species? Invasive Non-Native Species (INNS) are those that have been transported outside of their natural range, by human activities or naturally, and can damage our environment, the economy, our health and the way we live. The spread of INNS can outgrow, kill, or outcompete our local species which can impact food chains and biodiversity. They can lead to financial costs for fisheries, aquaculture, commercial and leisure marine sectors too. Where to report your sightings Please report all sightings to the Manx Wildlife Trust by to or by going to our website

Long wires of olive brown weed Covered in small leaves and tiny round floats May form very long lengths Fast

3 Liz Cook Wireweed Sargassum muticum A type of brown seaweed originally from the Pacific Ocean. It is found all round the Island, both intertidally and subtidally. First identified in 2005 in Castletown. Long wires of olive brown weed Covered in small leaves and tiny round floats May form very long lengths Fast growing, outcompetes local species and clogs propellers and harbours. Habitats Grows on hard surfaces in rock pools and shallow water. Liz Cook

Grows to around 25cm Felt-like texture Fronds are cylindrical and spongy Forms dense clumps Competes with

4 Chris Wood Green Sea Fingers Codium fragile A spongy green seaweed from Japan. First seen at Scarlett in 1960 and now at several locations around the Island. Grows to around 25cm Felt-like texture Fronds are cylindrical and spongy Forms dense clumps Competes with native species for space and is a potential nuisance to fisheries and aquaculture. Habitats It grows in rock pools and attaches to exposed rocks on the lower shore. Niall Moore

Oyster Thief Colpomenia peregrina A brown seaweed that forms an air-filled sac. First seen on the Island in Port Erin and Peel in 2006. It has also been seen at Fort Island and Langness.

5 Oyster Thief Colpomenia peregrina A brown seaweed that forms an air-filled sac. First seen on the Island in Port Erin and Peel in It has also been seen at Fort Island and Langness. It originates from the Pacific. Thin-walled sphere, easily torn Usually 1-7cm in diameter Reproduces rapidly, outcompetes native species and is a potential nuisance for aquaculture. Habitat Grows on rocks, shells (including oysters) and seaweeds, in the mid intertidal down to the shallow subtidal, especially in sheltered areas. Liz Cook

Large golden brown seaweed, 1-2m in length Divided frond with midrib Large reproductive frills just above the holdfast Covers

6 Abbi Scott Wakame Undaria pinnatifida This large brown seaweed originates from the NW Pacific and has currently only been sighted here once in 2011 at Port Soderick. Large golden brown seaweed, 1-2m in length Divided frond with midrib Large reproductive frills just above the holdfast Covers underwater structures and outcompetes native species for space, and potentially changes the ecosystem. Habitat Attaches to hard surfaces, both natural and man-made, from mid tide to shallow sublittoral. Predominantly marine. Abbi Scott

7 Harpoon weed Asparagopsis armata This red seaweed originated from Australia and has been found at Castletown, Peel and the Point of Ayre. Distinctive barbed branches Up to 30cm in length Rosy, pink in colour Unknown. Habitat Attaches to seaweeds and hard structures using its barbs, but may form rafts. Found from low intertidal areas down to shallow subtidal areas. Kathryn Birch

8 Pacific Oyster Crassostrea gigas A type of bivalve mollusc from Asia used in aquaculture in the UK. Currently only recorded on Ramsey harbour walls. Frilly oval shell with an average length of 10cm Shell may have dark purple patches It outcompetes and can smother local species, although so far this is not an issue on the Island. Habitats Grows on the lower intertidal shore on hard substrates and can be found in harbours and marinas. Lara Howe

9 Australian barnacle Austrominius modestus (Darwin s barnacle) (previously Elminius modestus) A small barnacle which is native to Australia. It can be found at various locations around the Island, including Ramsey, Castletown, Port St Mary, Langness, Douglas and Laxey. 5-10mm in diameter White in colour with only 4 outer shell plates and a low conical body Tolerant of a wide range of salinities Can dominate hard surfaces and displace native species and can be a nuisance as a fouling organism. Habitat Grows on hard surfaces such as rock and shell but also man-made structures. Lara Howe

10 Soft shell clam Mya arenaria This bivalve buries in the mud and originates from the Pacific. Currently only recorded in Port Erin bay. Chalky white, oval, elongated shell Can reach 15cm in length Leaves a characteristic key-hole shaped opening in the sediment They can alter habitats and form large dense populations. Habitat It lives in soft sediments in the intertidal and shallow sublittoral zones in bays and estuaries. Artist s impression

11 Leathery sea squirt Styela clava A brown solitary sea squirt that originates from Korea. Currently only found on Octopus reef, off Douglas. Up to 20cm long Leathery appearance, rumpled or knobbly surface The siphons are close together, with dark brown stripes inside Large populations can displace and dominate native species and can be a fouling pest on hulls and aquaculture infrastructure. Liz Cook Habitat Attaches to solid surfaces in harbours and marinas as well as natural surfaces.

2-4cm long Orange tipped siphon in adults Transparent body Distinctive C/U-shaped gut rather than an Sshape Can

12 Fiona Crouch Orange tipped sea squirt Corella eumyota A solitary sea squirt which has bright orange tips. It has been found in Douglas harbour in 2013 but not since then. It originates from the Southern Hemisphere. 2-4cm long Orange tipped siphon in adults Transparent body Distinctive C/U-shaped gut rather than an Sshape Can clog underwater machinery and can smother local wildlife. Habitat Attaches to solid surfaces, both man-made and natural. John Bishop

Bryozoan (small colonial organisms) Bugula simplex It is suspected that this bushy bryozoan has been identified in Manx waters. However this is yet to be confirmed.

13 Bryozoan (small colonial organisms) Bugula simplex It is suspected that this bushy bryozoan has been identified in Manx waters. However this is yet to be confirmed. It originates from the western Atlantic. Forms small erect, funnel shaped tufts Light brown in colour Multi-serial branches Fouling of underwater structures and competes with native species for resources. Habitat Predominantly found in harbours and marinas. Artist s impression

14 Bryozoan (small colonial organisms) Schizporella japonica A small colonial bryozoan first identified on pontoons in Douglas harbour in Originates from Japan. Forms encrusting mats Orange/red in colour Forms colonies up to 20cm in diameter Fouling of underwater structures and shellfish, which has implications for additional cleaning costs for shellfish aquaculture and competes with native species for resources. Habitats Will encrust rocks, algae and shells, as well as man-made structures. Liz Cook

It grows on all types of substrata including seaweeds, rocks, rope and other man-made underwater structures.

15 Artist s impression Red seaweed Antithamnionella ternifolia A rapid growing red, brown whorled seaweed identified back in 1905 in Port Erin. However, there have been no recent sightings reported. Its origin is unclear but likely to be from the Southern Hemisphere. It grows on all types of substrata including seaweeds, rocks, rope and other man-made underwater structures. Hook weed Bonnemaisonia hamifera This red algae was first identified back in 1956 in Port Erin, however, no recent sightings have been observed. Originates from the NW Pacific Ocean. It has hookshaped branches and can grow to 35cm in length. It can be found on the lower shore into the shallow subtidal. Its impacts are unknown. John Bishop

16 Liz Cook Carpet sea squirt Didemnium vexillum A fast growing extensive sheet or mat-forming sea squirt, not yet found on the Island. It has a firm, smooth texture with a varied colour range, from white to cream to orange/brown. It can have a veined or marbled appearance. It attaches to hard substrates where it can smother native species and underwater structures. Chinese Mitten Crab Eriocheir sinensis A brown crab which lives in freshwater but breeds in sea water. Originally from SE Asia and as yet not found on the Island. It has dense fur on its claws like mittens and a hexagonal body up to 8cm wide. Its legs are long and hairy. It can cause damage to riverbanks by burrowing and feeds on a wide range of native prey items and competes with native species. It is found in estuaries and rivers. FERA

Killer shrimp EA Dikerogammarus villosus An aggressive freshwater shrimp found in brackish water, originating from Eastern Europe. Not found on the Island yet.

It can be found in still or flowing water amongst hard substrates and vegetation.

17 Killer shrimp EA Dikerogammarus villosus An aggressive freshwater shrimp found in brackish water, originating from Eastern Europe. Not found on the Island yet. It is larger than our native shrimps, up to 3cm with a tail with distinctive cones. It can tolerate poor quality water. It kills and outcompetes native species. It can be found in still or flowing water amongst hard substrates and vegetation. Japanese Skeleton Shrimp Caprella mutica An aggressive shrimp originally from SE Asia, which is rapidly invading part of the UK. It has not been found on the Island yet. It can grow up to 49mm in length. It has large spines on the 3rd and 7th body segments in males. The female has orange spots on the broad pouch. They can clog nets and outcompete native species. They tend to be found in harbours and marinas. Liz Cook

GBNNSS Slipper limpet Crepidula fornicata Originally from the US and has yet to reach Manx shores. The shell is toenail shaped, up to 5cm long, white or cream coloured with orange/pink blotches.

They attach to solid surfaces in sediment in low intertidal or shallow coastal waters. Zebra mussel Dreissena polymorpha A freshwater mussel that can tolerate brackish water.

18 GBNNSS Slipper limpet Crepidula fornicata Originally from the US and has yet to reach Manx shores. The shell is toenail shaped, up to 5cm long, white or cream coloured with orange/pink blotches. Often forming stacks with the oldest shell at the bottom. They outcompete local species and can be major pests in oyster and mussel beds. They attach to solid surfaces in sediment in low intertidal or shallow coastal waters. Zebra mussel Dreissena polymorpha A freshwater mussel that can tolerate brackish water. It originates from Russia but has not been identified in Manx waters. The shell can be up to 3cm long with a distinctive D shape. Light and dark bands of colour give it its name. They can clog pipework and underwater equipment and outcompete our native species. They are found in slow moving brackish water such as docks. GBNNSS

19 Biosecurity in the Isle of Man The Isle of Man Government is taking steps, through a marine biosecurity plan, to make sure that good practices are in place to reduce the risk of introduction and spread of invasive non-native species in Manx territorial waters. Please refer to the Isle of Man Marine Biosecurity Plan that may be found on the Isle of Man Government website Further Information Further information about each of these species can be found on the Manx Wildlife Trust website and/or the Isle of Man Government website and For a more national view look at which is the website of the Great Britain non-native species secretariat.

20 Kindly sponsored by Sea-Changers

Marine Invasive Non- Native Species

Marine Invasive Non- Native Species The Manx Wildlife Trust has produced a photographic identification guide describing (with images) twenty marine invasive non- native species (INNS), including shrimps,