Reworked coccoliths: proxy to reconstruct Volturno hydrographic basin runoff variation

Coccoliths are the thin calcite platelets forming the exoskeleton of the coccolithophores, which are one of the main groups of marine phytoplankton. These photosynthetic organisms directly depend on environmental parameters within the photic zone of the oceans. Coccolithophores have one of the most abundant fossil record: their long evolutionary story (Late Triassic - present day), high evolutionary turnover, and phenomenal abundance in marine sediments have made them ideal fossils for high-resolution biostratigraphic studies. The reworked specimens generally disturb the biostratigraphic signal of a coccoliths assemblage. In shelf-dominated and river-dominated areas, the reworked coccoliths can provide information about land-ocean dynamic, sediment transport, and allow to account the continental terrigenous fluxes which are useful for paleoclimatic studies. We present a work in progress study in which we compare the distribution pattern of reworked coccoliths recovered in the C5_SW core versus the runoff model simulation (from 1951 to 2013 - CIRCE project) for the Volturno river hydrographic basin. The aim of this research is to achieve a new algorithm that will allow to extend the reconstruction of the variations of Volturno runoff up to 2000 years ago. The C5_SW core was recovered at 92m depth in the Gulf of Gaeta during the NextData_2013 cruise (NextData project - Paleoclimatic Data from Marine Sediments - WP1.5). The high resolution study of the first ~30 cm of the core (1 cm sample spacing), identified a broad correspondence between the reworking fluctuations and the runoff model data. These preliminary results would confirm the reliability of the reworked coccoliths to estimate the runoff quantitative fluctuations in the past.