4. Results and Discussion

4.1. Faunal spectrum

Thirty species of marine shells (20 bivalves, 10 gastropods), one sea urchin and one crustacean were identified (Figure 2) at the site of Clos des Châtaigniers. Mussels (Mytilus edulis) represent the majority of marine shell remains in all three types of quantification used (98% of the NISP, 75% of the MNI and 94% of total weight) (Figure 3). The high percentage of NISP for this species is linked to high levels of fragmentation. As a consequence, the relation between the Number of Identified Specimens and the Minimum Number of Individuals (221752/1490) shows that, for a single mussel individual, 149 remains were counted. It is thus often difficult to obtain total lengths and to describe the collecting strategies. From these correlations between total length and a small part near the teeth, 214 total lengths (RV = 105; LV = 109) have been reconstructed. These measurements ranged between 27 and 65mm, with a mean of 43.5mm, corresponding to adult individuals (Figure 4).

Seven other identified marine shells are edible and may have been part of the diet of the inhabitants of Clos des Châtaigniers: Littorina littorea, Barnea candida, Macoma balthica, Donax sp., Abra sp., Spisula sp. and Cerastoderma sp. (Figure 3). Nonetheless, the shells of these bivalves measured less than 20mm, a size typically rejected as being too small for human consumption. Thus the presence of these six species does not appear to be linked to human diet. The dogwhelk (Nucella lapillus) is represented by 20 medium-sized individuals (between 20 and 40mm). Half of them, however, show marks of marine worms of Polydora-type in their internal shell. These taphonomic modifications show that specimens of dogwhelk arrived dead and empty, without flesh, to the site. Twenty-one other species (Anomia ephippium, Ostrea edulis, Solen marginatus, Acanthocardia tuberculata, Scrobicularia plana, Spisula solida, Buccinum undatum, Aequipecten opercularis, Mimachlamys varia, Ruditapes decussatus, Gari sp., Phaxas pellucidus, Lacuna pallidula, Littorina obtusata, Bela powisiana, Nassarius reticulatus, Epitonium clathrus, Corbula gibba, Ocenebra erinaceus, Mactra sp. and Gibbula sp.) are represented by only 1 to 13 individuals (Figure 3). The small quantities of these marine invertebrates are unlikely to indicate intentional collecting for human consumption. In addition, some of these species are small in size and evidence shows that deposited specimens were already dead when they arrived at the site. Only one fragment of sea urchin, species unidentified, was found (Figure 2, 31). Finally, some barnacles, belonging to the order of Cirripedia crustaceans, were observed (Figure 2, 32) and probably brought to the site during the transport of the mussels.

In summary, the size and quantity of mussel remains show that this shellfish was consumed by past inhabitants. However, the consumption of the other thirty-one identified marine invertebrates cannot be proved because of their presence in small quantities (Figure 3), small sizes and/or observed taphonomic modifications.