The seasonal water temperature cycle in the Arctic Dicksonfjord (Svalbard) during the Holocene Climate Optimum derived from subfossil Arctica islandica shells

Abstract

Future climate change will have significant effects on ecosystems worldwide and on polar regions in particular. Hence, palaeo-environmental studies focussing on the last warmer-than-today phase (i.e. the early Holocene) in higher latitudes are of particular importance to understand climate development and its potential impact in polar systems. Molluscan bivalve shells constitute suitable bio-archives for high-resolution palaeo-environmental reconstructions. Here, we present a first reconstruction of early Holocene seasonal water temperature cycle in an Arctic fjord based on stable oxygen isotope (δ 18 O shell ) profiles in shells of Arctica islandica (Bivalvia) from raised beach deposits in Dicksonfjorden, Svalbard, dated at 9954-9782 cal. yr BP. Reconstructed maximum and minimum bottom water temperatures for the assumed shell growth period between April and August of 15.2°C and 2.8°C imply a seasonality of about 12.4°C for the early Holocene. In comparison to modern temperatures, this indicates that average temperature declined by 6°C and seasonality narrowed by 50%. This first palaeo-environmental description of a fjord setting during the Holocene Climate Optimum at Spitsbergen exceeds most previous global estimates (+1-3°C) but confirms studies indicating an amplified effect (+4-6°C) at high northern latitudes.

Exploring the impact of diagenesis on (isotope) geochemical and microstructural alteration features in biogenic aragonite

“…Thus, spatially resolved analyses were performed prior to this study. Results are shown in Table and compared with published data (Schöne et al ., ; Eagle et al ., ; Henkes et al ., ; Beierlein et al ., ) from different locations. An unaltered shell was analysed for patterns in isotope ratios.…”

Dynamic Holocene glacial history of St. Jonsfjorden, Svalbard

“…; Beierlein et al . ). Studies of modern processes and glacier response to increased ocean temperatures on Svalbard (Bartholomaus et al .…”

Oxygen Isotope Composition of Arctica islandica Aragonite in the Context of Shell Architectural Organization: Implications for Paleoclimate Reconstructions

“…This has been confirmed by observations and experimental studies with shells of a variety of bivalve species (e.g., Grossman & Ku, 1986;Owen et al, 2002;Wanamaker et al, 2006). Shell-based water temperature reconstructions are increasingly used in environmental research with applications in modern times (e.g., Mette et al, 2016;Sch€ one et al, 2004Sch€ one et al, , 2005Watanabe & Oba, 1999) and the distant past (e.g., Beierlein et al, 2015;Ivany & Runnegar, 2010;von Leesen et al, 2017).…”

“…In sclerochronological studies, seasonal oxygen isotope profiles are commonly used in paleotemperature reconstructions (e.g., Beierlein et al, 2015;Sch€ one et al, 2004Sch€ one et al, , 2005von Leesen et al, 2017) . Our results suggest that the use of isotope profiles from the microstructurally different shell layers might affect estimated temperatures.…”

“…A. islandica is one of the most frequently studied bivalve species and the most frequently used species in paleoenvironmental research of the North Atlantic region (Sch€ one, 2013). Many studies use stable isotope profiles of modern and subfossil shells of A. islandica as an archive of environmental variability (e.g., Beierlein et al, 2015;Reynolds et al, 2016;Sch€ one et al, 2005). Yet, to our knowledge, no work has focused on estimating the potential influence of microstructural organization on the stable isotope data of the shells of this species.…”