This work focuses on investigating the potential of calcein and manganese as growth
markers of the common cockle (Cerastoderma edule) in the bay of Somme
(France). Recapture of shells, previously marked using a chemical marking and then bred in
natural conditions, was performed in order to determine the shell growth patterns. Calcein
marking has shown a fluorescent increment in shells after only 30 min immersion time at
150 mg L-1, but also for shells immersed 3 h at 50 mg L-1. Likewise,
manganese shell marking was revealed under cathodoluminescence for shells immersed 1 h at
120 mg L-1 as well as for shells which spent 4 h at 90 mg L-1. A
numerical analysis performed on each marked cockles has revealed 23 micro-increments
between the mark and the ventral edge of the valves, corresponding to the 23 tides that
occurred during the 12 days at liberty post marking. The periodicity of increment
formation is thus validated for a tidal frequency. The growth rates of C.
edule, ranged from 11.67 to 19.94 μm d-1, decreased
significantly with increasing shell length. This preliminary study gives a clue to the
understanding of cockle growth and could be used in shellfish production for cockle age
monitoring, but also for chemical analysis to learn more about biomineralization process
of this species.