INNS
Marine Invasive Non-Native Species are a clear problem for our Marine Protected Areas and only add to the problems the ecosystems and the species comprising them, are already facing (some which are considerable and long-lived).
There remains ongoing decisions with regard to the route to management of these species once they’ve arrived and established and to reducing the pathways on which they’re arriving. Helping to monitor and show the problem as it is on Welsh shores is clearly going to be of benefit.
More links and seconds where these species can be found in the INNS talk by Chloe Powell-Jennings NRW in 2020 (video link, below):
harpoon weed/gwymon bachog (Asparagopsis armata) @ 37mins 32seconds
carpet sea squirt/chwistrell fôr garped (Didemnum vexillum) @ 3mins 28seconds
asian shore crab/cranc traeth Asiaidd (Hemigrapsus sanguineus) @ 25mins 20seconds
wakame/morwiail asennog (Undaria pinnatifida) @ 36mins 08seconds
leathery sea squirt/chwistrell fôr arw (Styela clava) @ 12mins 31seconds
bonnemaison’s hookweed (Bonnemaisonia hamifera) @ 38mins 48seconds
orange tipped sea squirt/chwistrell fôr ag ymylon oren (Corella eumyota) @ 9mins 55seconds
compass sea squirt/chwistrell fôr gwmpawd (Asterocarpa humilis) @ 7mins 49seconds
Two further species not mentioned in the talk:
oyster thief (Colpomenia peregrina)
orange striped anemone/anemoni melynrhesog (Diadumene lineata)
For a world update on INNS species the CABI website is informative. It has data sheets on INNS e.g. Corella eumyota. See the contents along the side for a history of invasion, pathways, natural enemies, ecology etc.
More INNS - seaweeds
harpoon weed/gwymon bachog (Asparagopsis armata)
©Kathryn Birch INNSS
- this red algae has two phases – one phase (the sexual phase) is a delicate, branched, long-growing (up to 30cm) and has barbs on the branches
- it is pink-ish in colour
- branches are bare lower down and densely tufted further up
- it attaches to other algae with barbed root-type structures called rhizoids
- this phase can be absent for many years and is seen in extreme low tide areas and beyond
- the other phase (asexual phase) is pink in colour too
- it grows as a ball of branching syphon-type structures, 1-3cm diameter
- within the ball, it is irregularly-branched
- grows attached to algae, but sometimes free-living
- is seen in extreme low tide areas
wakame/gwymon wacame (Undaria pinnatifida)
©Kathryn Birch INNSS
- a large kelp species found in the intertidal region (rarely found below low tide mark)
- grows 1-3 metres long
- blade (leaf) is broad, has a midrib, wavy edges and is lance-shaped
- there is a significant frilling of the stipe (stem), just above the holdfast, later in the season
- likes marinas.
- This is a Section 9 species – meaning it is an offence to plant or otherwise allow this species to grow in the wild.
bonnemaison’s hookweed (Bonnemaisonia hamifera)
©Ignacio Barbara – algaebase
- a species of red algae
- has two phases of growth which look different
- one form is feathery and delicate, in appearance (this is the reproductive phase, present Mar-June)
- it attaches to other seaweed using rounded hooks, but grows from a main axis
- grows to 25cm long
- this form is brown-red or purple-pink in colour
- the non-reproductive phase is present all yr, but most obvious Oct-March
- highly branched and filamentous, looks like cotton wool
- brown-red in colour
- grows to about 2.5cm in diameter
- tends to be very low shore in rockpools
oyster thief (Colpomenia peregrina)
©North Wales Wildlife Trust
- bulbous brown algae, 1-7cm in diameter
- grows as lobed-balls, hollow inside, dry to the touch and easily torn open
- green-olive in colour
- grows on rocks, algae, shells
- likes sheltered shore areas
- NB don’t confuse for the native low-growing, bulbous algae called Leathesia marina which is gelatinous and breaks up in the hand, whereas Colpomenia is smooth, air-filled and rips like paper.
Some INNS - squirts
carpet sea squirt/chwistrell fôr garped (Didemnum vexillum)
©CCW-NRW INNSS
- lives on hard substrate in coastal areas
- colonial squirts which form lobes within the colony which is an ID feature
- lobes are irregular – can be cylindrical, rope-like, flat, bulbous or branching and of considerable size, reaching as much as a metre in length
- forms sheets/mats
- can be if different colours – tan, cream, yellow, orange, pink
- can grow on other species
- growing in Holyhead marina where efforts have been attempted to smother and kill, but unsuccessfully to date.
- Very difficult to ID in field, important to collect as many pic as possible and GPS of location, ideally.
leathery sea squirt/chwistrell fôr arw (Styela clava)
©Chris Wood MCS INNSS
- solitary sea squirts with each individual having its own stalk
- looks thick and leathery in appearance with rumpled/ knobbly surface
- the inhalant and exhalant syphons are both situated at the top and relatively close together
- grows in a long, club-shape
- can be up to 12cm long
orange tipped sea squirt/chwistrell fôr ag ymylon oren (Corella eumyota)
©North Wales Wildlife Trust
- a solitary sea squirt, which can often attach to others of the same species forming aggregations
- each individual grow to 2-4cm long
- attach along their right side,
- syphons on different sides (one on one side and then one at the top)
- transparent body wall which is smooth
- grows up to 8cm
- the gut, which can be seen through the translucent body lies in a smooth curve, U-shaped (and not S-shaped, like a native squirt Ascidiella aspersa)
- the native squirt (mentioned above) is also attached at the base and not the side and so looks more upright.
compass sea squirt/chwistrell for gwmpawd (Asterocrpa humilis) 
©John Bishop, MBA.
- orange-red sea squirt
- relative large growing to 4cm
- attached at base
- syphons situated on different sides (one right at end away from attached side and the other on the side of animal)
- warty-looking across surface, often
- when syphons are open they have clear patterning of pale stripes at the outer edge(sometimes there stripes can be seen on partially closed syphons too)
- native species look similar stripes differ and lack warts
A couple more INNS
orange striped anemone/anemone melynrhesog (Diadumene lineata)
©John Bishop-MBA
- small, delicate anemone
- column usually olive-green/brown
- stripes along column are commonly orange, (sometimes yellow or white)
- long, slim, grey-ish tentacles (up to 100)
- grows in associations with mussels and oysters
- appears to like brackish water for a period of time
- NB can look like a young plumose, but this species is not striped.
asian shore crab/cranc traeth Asiaidd (Hemigrapsus sanguineus)
©Jack Sewell, MBA
- small crab up to 4.5cm across carapace
- carapace is square in shape with 3 teeth at sides of the eyes
- carapace between the eyes is relatively straight
- variable colours orange-brown to greenish-black
- distinct white claws and clear banded colour on legs
- lives on exposed rocky shores, but also in sediment and mussel beds
- is one of two Non-Native Hemigrapsus species the other being smaller, with the similar white claws, square carapace, three spines at eye sides and variable colours.
The next section is the quiz. You will be tested on what you’ve learnt so far. INNS are particularly tricky to learn to ID as unless they’ve become established, getting your eye in becomes difficult. Make the most of training sessions, when offered and the occasional watch of the video and read of information in this section will help to remind you of features to keep in mind when out on shore.
Good luck!