Ingestion, enzymatic digestion and absorption of particulate detrital matter derived from six different vegetal sources by the common cockle Cerastoderma edule was analyzed in a series of seasonal experiments performed in March, May and October 2005. Two green macroalgae: Ulva lactuca and Enteromorpha sp ; two vascular plants: Spartina maritima and Juncus maritimus , the red macroalgae Gracilaria gracilis ; and the microalgae Isochrysis galbana were used in experiments. Detrital matter was elaborated by freeze-drying, grinding and sieving ( Ulva and Enteromorpha ) and lowest to those fed the vascular plant Juncus maritimus . Recorded significant differences in enzymatic digestibility among detritus were found to explain ≈ 40% of differences recorded in AR, and the following regression could be fitted: AR = 0.232 (± 0.032) ⁎ Digestibility + 0,072 (± 0.015); r 2 = 0.415; F = 51.036; p Ulva and Enteromorpha was found to be significantly correlated with cellulase activity in the digestive gland, whereas digestibility of Juncus , Spartina and Gracilaria was correlated with xylanase activity. Obtained correlations are discussed in the frame of contrasting conclusions in the literature regarding the importance of detritus as a food source for bivalves.
