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Sclerochronology and 14C dating applied on bivalve Glycymeris pilosa from the Adriatic Sea

This study combines radiocarbon analysis and sclerochronology research, an approach that to the best of our knowledge, has not yet been applied using bivalves from the Mediterranean Sea. We analysed shells from the North Adriatic Sea: live- and dead-collected specimens of the infaunal bivalve Glycymeris pilosa (Linnaeus, 1767) and two dead-collected specimens of Glycymeris sp. According to crossdating results, growth increment time series obtained from acetate peels of the dead-collected G. pilosa (S3FP11) indicate the potential for creating longer chronologies from live and dead-collected specimens. Based on the radiocarbon results obtained from a growth increment assigned to AD 1950 in a live- collected shell, the reservoir age (R) and reservoir correction (ΔR) are 264 ± 23 years and -6 ± 32 years, respectively. One of the three sub-fossil shells reflected 14C bomb peak and could be assigned to a time period from AD 1965 to AD 2013. The other two sub-fossil specimens were dated with reservoir age correction calculated as mean from AD 1950 increment growth and ΔR reported by Siani et al. (2000 ; Radiocarbon 42:271-80) and, by use of Bayesian analysis, were placed in periods from 15th to 17th century (S3F5) and from 17th to 19th century (S3F3). The greatest longevity was seen in the dead-collected Glycymeris sp. specimen S3F3, estimated to be ~130 years (started growing AD 1678-1742 and died AD 1826- 1860), indicating the potential to extend Glycymeris growth increment chronologies to past centuries. The highest Δ14C values obtained correspond to the calendar year 1974. The 14C record obtained from G. pilosa correlates well with the modelled surface ocean (mixed-layer) bomb pulse curve (Reimer et al. 2009 ; Radiocarbon 51:1111-50) and with model developed for Mediterranean Sea by Ayache et al. (2017 ; Biogeosciences 14: 1197-213). Research has been conducted in a framework of the project SCOOL (IP-2014-09-5747) supported by the Croatian Science Foundation.

sclerochronology ; radiocarbon dating ; Glycymeris pilosa ; Adriatic Sea

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