Shell sclerochronology and stable isotopes of the bivalve Anomalocardia flexuosa (Linnaeus, 1767) from southern Brazil: Implications for environmental and archaeological studies

This study presents the first stable isotopic and sclerochronological calibration of the bivalve Anomalocardia (Linnaeus, 1767) in relation to environmental variables in a subtropical coastal area of southern Brazil. investigate incremental shell growth patterns and δ18O and δ13C values of modern specimens collected fromthe Laguna Lagoonal System (LLS). Shells of Anomalocardia flexuosa are also one of themain biological of pre-Columbian archaeological shell mounds and middens distributed along the Brazilian coastline. therefore selected archaeological specimens froma local late Holocene shell mound (Cabeçuda) to compare stable carbon and oxygen isotope values with those of modern specimens. Shell growth increments, δ18O and δ13C values respond to a complex of environmental conditions, involving, for example, the effects of and salinity. The isotopic information extracted from archaeological specimens from Cabeçuda midden in the LLS indirectly indicates that environmental conditions during the late Holocene were different day. In particular, intra-shell δ18O and δ13C values of archaeological shells reveal a stronger marine at 3 ka cal BP, which is in contrast to the seasonal freshwater/seawater balance that currently at the LLS.