Natur am Byth Webinar 1: Molluscs

From the tiny Whorl Snails of sand dunes, to the mysterious Arctic Pea Clam of mountain lakes, and the Native Oyster once abundant in our seas, molluscs survive in wild corners all around Wales.

Learn about how and where they can be found and recognised, how they are connected to people, and what is being done to help save them from extinction. This webinar is one of a series of online species identification experiences, hosted by our natural history curators at Amgueddfa Cymru. Using photos and video from the Museum and from outdoor habitats, our expert curators will take you on a “virtual field trip” revealing what makes each species unique, and what it takes to protect them.

The species featured include:

• Native Oyster (Ostrea edulis)
• Arctic-Alpine Pea Clam (Euglesa conventus)
• Narrow-mouthed Whorl Snail (Vertigo angustior)
• Geyer’s Whorl Snail (Vertigo geyeri)
• Desmoulins’ Whorl Snail (Vertigo moulinsiana)

 

Presenters: Ben Rowson & Anna Holmes

This webinar deals with the five molluscs in the Natur am Byth project: three Whorl Snails (Vertigo species), the Native Oyster (Ostrea edulis) and the Arctic Pea Clam (Conventus conventus).

Whorl Snails (Vertigo species) are sensitive to moisture levels and can live in tiny areas of specialized habitat. They can reproduce without mating, but spread very slowly. There are 10 species in Wales, all of them tiny (about the size of sesame seeds). Showing them under the microscope reveals just how much smaller than “ordinary” snails they are. Whorl Snails can be mistaken for Chrysalis Snails (Lauria and Pupilla) which, although small, are actually bigger. Key differences in the shells are demonstrated.

The Narrow-mouthed Whorl Snail (Vertigo angustior) is rare but easily recognised because it coils to the left. It is lives in sand dunes and is found by getting close to the ground, in sieved vegetation, or by suction sampling. It needs a humid thatch of grass. Natur am Byth has commissioned surveys of the known (and unknown) dune systems in South Wales to see how the species is faring. At least one new site has been found.

Desmoulin’s Whorl Snail (Vertigo moulinsiana) is a larger and voluptuous species with a flaring lip. It likes luxuriant marshes and can be found by beating reeds over a tray. It is very rare in Wales, but there is a large population on the Afon Penrhos near Pwllheli.

Geyer’s Whorl Snail (Vertigo geyeri) is extremely rare (and also tricky to identify). It likes short pastures with seepages, a post-glacial relict habitat. It has been searched for intensively but seems to remain only at one site in Wales, at Waun Eurad on Anglesey. It is thus at real risk of extinction in Wales.

All three Vertigo species are threatened by changes in hydrology, over-grazing or under-grazing, and being shaded out by sedges or trees. As well as surveys, Natur am Byth is involved with management of their habitats and finding ways to safeguard their future.

Bivalves are aquatic filter feeders with paired shells. They move little, but can spread via their larvae.

The Native Oyster (Ostrea edulis) has been harvested and eaten for centuries. A particular centre in Wales was Mumbles, near Swansea. Overfishing exhausted the Welsh beds in the 19th century and there are now several restoration projects. The native species is readily confused with two non-native oyster species, two deep-water species, and three other species arriving by rafting from the Caribbean. The key differences between the three oyster species common in Wales, including juveniles, are demonstrated. Oysters are also susceptible to disease and pollution. Encouraging a local fishery, as at Mumbles, might even help save the species in Wales.

The Arctic-Alpine Pea Clam (Conventus conventus) is a tiny, obscure species. In Wales it has been found only in four high altitude lakes in Snowdonia. Pea Clams are a diverse group that can be very challenging to identify. The key features of C. conventus are illustrated. It is a glacial relict species that is threatened by warming climate and lake pollution. Natur am Byth has been revisiting its known sites and attempting to find others in Snowdonia as well as raising the profile of the species.