Reconstructing environments of collection sites from archaeological bivalve shells: Case study from oysters (Lyon, France)

Abstract

International audienceThe flat oyster, Ostrea edulis, was consumed as a luxury dish by the Romans in antiquity. Numerous shells are found in archaeological sites in the Lyon region, Central France. This area is located over 250 km away from the nearest coastline (the Mediterranean Sea) and little is known about the origin of these oysters prior to transport for consumption. The chemistry of biogenic carbonates reflects that of the fluid they precipitate from at the time of formation. Stable isotopes and Mg/Ca ratios in oyster shells have previously been used as palaeoenvironmental proxies. As Mg/Ca ratio amplitude in bivalve shells has been reported to differ according to local hydrologic settings, we suggest that geochemical differences observed in each shell can be used to identify the type of environment (e.g. estuary, lagoon or marine) from which the specimens originated

The archaeology of 19th century oyster consumption in Melbourne

“…Since changing oyster supplies historically could equate with multiple sources for the archaeological assemblages, correctly assigning a historical fishery provenance may ultimately depend on genetic or other attributes of the shell itself (e.g. Hayer et al, 2021;Mouchi et al, 2018Mouchi et al, , 2021.…”

Geochemistry of Bivalve Shells As Indicator of Shore Position of the 2^nd Century BC

“…The two resulting halves of each umbo were used to make thin sections and isotopic sampling. Thin sections were used for microscope and cathodoluminescence observations to ensure the pristine state of the shells and to obtain a seasonalscale temporal calibration (Langlet et al 2006;Mouchi et al 2018). Cathodoluminescence observations were performed on a Cathodyne OPEA cold cathode with operating settings of 15-20 kV and 200-400 µA•mm -2 .…”

“…As bivalve shells are built by the organism from chemical elements in its environment, the composition of the carbonate shell constituents can be used to reconstruct physicochemical settings of the living locality (Grimstead et al 2013;Leng & Lewis 2016;Mouchi et al 2018). In particular, the relative proportion of oxygen stable isotopes (compared to a standard value; δ 18 O) in biogenic carbonates are often used to reconstruct seawater temperature (Craig 1965).…”

Annual Growth Patterns and Interspecimen Variability in Mg/Ca Records of Archaeological Ostrea edulis (European Oyster) from the Late Mesolithic Site of Conors Island

“…Thus, Mg/Ca ratio variability cannot reliably be avoided by for example sampling at an equal distance to the hinge. Further, interpretations that imply environment specific or species specific influences on the Mg/Ca ranges based on line scans need to verify these influences using 2D mapping (Bougeois et al 2016;Mouchi et al 2018). Ultimately, these differences do not only illustrate the need to map elemental ratios over line scans, but also the need for increased sample sizes that accurately depict the wider variability of the spatial patterning of elemental ratios.…”