Volunteer sports divers from the Nautical Archaeology Society and the Marine Conservation Society are recording the marine life which now inhabits some of the Great War wrecks.
The surveys provide a snapshot of the evolution of an artificial reef. The first organisms to arrive are marine larvae which attract more and more species to take advantage of available food. On the shipwrecks in Welsh waters, the ecosystems that develop often include sponges, hydroids, sea anemones, bryozoans and nudibranchs, which prefer hard surfaces to attach to and do not thrive on sandy or muddy seabeds.
High numbers of fish are normally found swimming close by, using the wreck as shelter or permanent habitat.
The marine life on and around shipwrecks can add significantly to local biodiversity.