Individual foraminiferal analysis: A promising tool for high-resolution temperature and pH reconstruction

In this study, we systematically evaluate the El/Ca and δ11B in individual benthic foraminifera and show that physical and chemical cleaning prior to analysis is vital to avoid the potential influence of sedimentary contamination, even when careful consideration of the time resolved analysis was done. By analysing Holocene epifaunal benthic foraminifera species Cibicidoides wuellerstorfi from a deep ocean core site (ODP Site 999), we conclude that intra- and inter-test variabilities are mainly regulated by ontogenetic effects resulting in inter-test variabilities of ± 0.14 mmol/mol Mg/Ca, ± 14 μmol/mol B/Ca and ± 0.18 ‰ δ11B. Application of the IFA method to epifaunal benthic foraminifera species Cibicides lobatulus from a box-core close to the Western Channel Observatory in the English Channel, UK allowed us to reconstruct bottom water temperature and carbonate parameters from the pre- and post-industrial era. By demonstrating that individual-level variability in reconstructed temperature and pH tracks seasonal trends in the available contemporaneous water-column instrumental measurements at the same site, we both provide a ground-truthing multi-proxy IFA methodology and also demonstrate the potential for benthic IFA to provide seasonal-scale reconstructions of ocean climate over hundreds to millions of years.