Spatio-temporal variability in the fatty acid profile of the adductor muscle of the common cockle Cerastoderma edule and its relevance for tracing geographic origin

•Fatty acid (FA) profile of the adductor muscle (AM) of cockles differs among ecosystems.•Shifts in n-3/n-6 ratio, 15:0 and 17:0 discriminated specimens from different ecosystems.•FA profile of AM can display significant interannual shifts in the same ecosystem.•Despite temporal variability FA profiles of AM can be used to trace geographic origin.

The present study aimed to identify the potential existence of spatio-temporal variability in the fatty acid (FA) profile of the adductor muscle (AM) of a commercially important bivalve, the common cockle Cerastoderma edule, and determine if such variability can be used to trace their geographic origin post-harvesting. Common cockles were sampled in eight ecosystems along the coast of mainland Portugal, as well as in two different channels within one of those ecosystems over two consecutive years. Results showed significant differences in FA profiles among ecosystems, namely due to different levels of eicosapentaenoic acid (EPA; 20:5n-3), arachidonic acid (20:4n-6), ratio of polyunsaturated FA (PUFA) n-3/n-6, monounsaturated FA (MUFA; 18:1n-9 and 20:1n-9/11) and bacterial FA (15:0, 17:0 and 18:1n-7). FA profiles also displayed significant differences between two consecutive years in channels from the same ecosystem. Overall, while the FA profile displayed by the AM of C. edule can be successfully used to trace their geographic origin, the existence of temporal variability requires a periodical verification of FA signatures to identify potential shifts, namely when comparing specimens from the same ecosystem.