Causes of shell scarring in dog cockles Glycymeris glycymeris L.

Experimental studies were conducted to investigate the possible causes of s hell scars in the bivalve mollusc Glycymeris glycymeris, including fishing disturbance, predator attacks and burrowing activity. Individuals collected from an area of sea bed experimentally fished once by a scallop dredge 12 months previously did not display significantly more shell scars than those collected before fishing or fi om a control area. In the laboratory, Glycy meris offered to the predatory crab Cancer pagurus had a significantly high er incidence of scars seen in acetate peels of shell cross-sections than co ntrol shells. However, scarring on Glycymeris excavated from the sediment a nd left to reburrow was nor significantly different from those in an undist urbed control group. Currently, it is not possible in C. glycymeris to diff erentiate between scars caused by fishing disturbance or natural disturbanc es, either on the grounds of visual appearance or position of damage. (C) 2 001 Elsevier Science B.V. All rights reserved.