No interactions present.
It's unlikely that this would have been a bird. Allegedly mink and otters would prey on freshwater mussels, you would need to check for teeth marks on the shell. It would depend on what predators you have at Bray Lake.
Another alternative is humans, they are used as fishing bait occasionally.
Chris Brooks - www.dragonfly-images.co.uk
My Flickr site - www.flickr.com/photos/ceb1298
Thanks, Chris, I shall look for tooth or tool marks next time I visit.
Today I saw a crow extracting and eating the contents of one of the above bivalves at the same location. When I looked (after the crow had gone) the shells were well broken up. The crow had been standing on the pieces to pull off the meat, but I cannot think that would have broken the shells.
Unfortunately I did not see just how the crow found the shell pieces initially. I shall have to watch more attentively; the crows are often around there. Usually I am watching for kingfishers instead! (See Berks Birds http://www.berksbirds.co.uk/)
Lat/Lng: 51.5, -0.6906
OS grid ref: SU909787
Next to a lake used for water sports