Field Meeting at Bavelaw Marsh, Midlothian 24th September 2005

The aim of this meeting was to look for the mud snail, Omphiscola glabra, a rare species that has been proposed as a BAP priority species (see Mollusc World 8, p 22). This species was previously reported from Bavelaw Moss 50 years ago by A.R. Waterson, but without any clear indication of precisely where it was found.

Bavelaw Marsh is a large area of shallow water above two reservoirs, Threipmuir and Harlaw, near Balerno, a few miles south of Edinburgh, over 800 feet up on the lower slopes of the Pentland Hills. On a beautiful early autumn day, a select group assembled to see in O. glabra was still present. We initially visited the marsh itself, an open area of shallow water frequented by ducks and geese, and with less vegetation than we had hoped. Nevertheless, it proved to contain plenty of molluscs round the edges of the water (see list below), and in fact was felt to be too rich in species and individuals to be a likely habitat for the mud snail. We wondered if the adjacent Red Moss, a raised bog managed by the Scottish Wildlife Trust, might be a more suitable site for the mud snail, and accordingly transferred our attentions to it. Much of the area is covered with a variety of mosses, which were rather dry at the time of our visit. However, there were a number of ditches and a pond that merited closer inspection. The ditches were in fact rather peaty and yielded nothing, but the pond (see illustration) looked more promising, and we spent some time exploring it. Alas, there was nothing in the mud of the pond or in the marginal vegetation, though we turned up a few slugs and snails in the surrounding grass (see the list below).

So we failed to find the mud snail, but we have not given up hope – there are still more areas that could be worth investigating. And even if our tally of species was small, we had a lovely day out in the sunshine, with flocks of geese calling as they flew overhead.

Species found at Bavelaw Marsh and Red Moss, 24th September 2005 Bavelaw Moss

• Lymnaea peregra
• Bathyomphalus contortus
• Gyraulus albus
• Pisidium sp.
• Red Moss
• Cochlicopa sp.
• Discus rotundatus
• Arion ater
• Arion intermedius

Fig 1 Red Moss of Balerno

Fig 2 Pond on the Red Moss