Age determination and shell growth of Chamelea gallina (Bivalvia: Veneridae) in the western Mediterranean

The pattern of microgrowth bands in shell sections of the Mediterranean clam Chamelea gallina shows a seasonal variation in width.Widely spaced growth bands are formed in winter and late spring between January and June, whilst narrow growth increments are deposited in summer and early autumn between August and October, following the maximum summer seawater temperature.The warm summer seawater temperature of 33 "C in the western Mediterranean may be responsible for the suppression of shell growth, as evidenced both by the narrowing of the growth increments and by the later appearance of clefts in shell sections.There is no correlation between spawning and the formation of clefts in the shell of C. gallina.The annual pattern of narrow and wide growth increments has been used to estimate the age of C. gallina and to construct growth curves for this species from the eastern coast of Spain.Growth curves for the clams, determined from the internal microgrowth bands and from the spacing between the clefts in shell sections, differed from the curve calculated using surface growth rings.