First cross-matched floating chronology from the marine fossil record: data from growth lines of the long-lived bivalve mollusc Arctica islandica

Abstract

Integrated understanding of phasings within the climate system over the last glacial cycle, and at higher frequencies, is inhibited because no absolute timescale for the marine environment currently exists. This precludes identification of forcings and feedbacks, accurate temporal calibration of the marine radiocarbon reservoir effect, and the application of radiocarbon as a proxy of short-timescale ocean ventilation. This has prompted a search for annually banded marine proxies in the hope of establishing an accurate marine chronometer. We present annual growth band series from dead-collected specimens of the long-lived bivalve mollusc Arctica islandica from the northern North Sea and demonstrate their successful cross-matching, with the general timescale context independently verified by radiocarbon dating. Though at present limited to only a few statistically cross-matched series, this has already generated the longest Arctica chronology, and the first ‘floating’ chronology constructed entirely from marine fossils. The record covers the period from c. AD 1000 to 1400 and integrates a 267-yr series from the longest-lived Arctica specimen yet recorded from the North Sea. This breakthrough in cross-matching demonstrates that Arctica islandica can fulfill its potential as the ‘tree of the sea’ to provide an absolute timescale for the marine environment.

Very Long-Lived Mollusks Confirm 17th Century AD Tephra-Based Radiocarbon Reservoir Ages for North Icelandic Shelf Waters

“…This system facilitates increment measurement using an automated cursor that feeds directly into a data spreadsheet and enables both the growth increment series and their axis of measurement to be digitized. Because of the nature of the A. islandica growth curve, where yearly growth can vary by 2 orders of magnitude over the lifespan of the animal, the raw increment-width data are treated using a high-pass filter that removes the low-frequency ontogenetic growth trend to produce a standard shell growth-increment plot for each shell (Scourse et al 2006). This involves generating the natural logarithm of the data to remove the different orders of magnitude and the residuals are then taken from a 15-yr spline through the data ( Figure 4A).…”

“…Acetate peel replicas (Agar Scientific; 35 μm) of the polished and etched surfaces were prepared and examined in transmitted light under magnifications of ×2.5, ×4, and ×10 using a Leica Laborlux S microscope. Following the production of acetate peel replicas, annual growth increment widths can be measured and recorded either from the outer shell surface (Schöne et al 2005a) or along the hinge plate in the umbo (Scourse et al 2006). The hinge plate was used because the growth increments here are most obvious ( Figure 3C).…”

“…More negative ΔR values indicate a dominant Atlantic water mass, while positive ΔR values indicate a dominant Arctic water mass (Eiríksson et al 2004). to tropical corals; this result illustrated important hydrographic differences controlling the rates at which atmospheric carbon is mixed into the oceans, and it also suggested a deepwater source for the waters of Georges Bank. Furthermore, annual growth records and geochemical information (δ 18 O) derived from the shells of A. islandica have been used to study past ocean conditions in the North Atlantic (Weidman et al 1994;Witbaard 1996;Witbaard et al 1997Witbaard et al , 2003Marsh et al 1999;Marchitto et al 2000;Schöne et al 2003Schöne et al , 2004Schöne et al , 2005aScourse et al 2006;Helama et al 2007;Wanamaker et al 2008). These shell-based records, like tree rings, offer a significant advantage of being absolutely dated (Thompson et al 1980;Jones 1980), and therefore enable the generation of ultrahigh-resolution paleoenvironmental records based on an absolute timescale (Marchitto et al 2000).…”

Evaluation of CMIP5 models over the northern North Atlantic in the context of forthcoming paleoclimatic reconstructions

“…The first region is located in the North Sea (NS) at 58.5°N, 0.5°E and the second north of Iceland (Icelandic Self-IS) at 66.5°N, 19.5°W. These sites where chosen based on previous collection sites and studies (Wanamaker et al 2008a(Wanamaker et al , b, 2012Scourse et al 2006;Butler et al 2013). It is also important that the SST trends calculated by the models over NA share a similar distribution of the observed trends at a certain level of statistical significance.…”

“…The variability in the shells growth increment widths, which are the portions of shell between consecutive growth lines (Schöne 2013), and in the geochemical signature from the shell material ( 14 C, δ 18 O, δ 13 C) relates to changes in environmental conditions (Witbaard and Klein 1994;Schöne et al 2011;Wanamaker et al 2011). In addition to the high temporal resolution of Arctica islandica, the reconstructions derived from its records can be crossvalidated, absolutely dated (Scourse et al 2006;Butler et al 2010) and offer significant advantages in evaluating long-term NA marine climate dynamics ). Records of Arctica islandica can be used to reconstruct sea water temperatures (Eagle et al 2013;Wanamaker et al 2016), salinity (Gillikin et al 2006), major NA climate modes like the Atlantic Multidecadal Oscillation (AMO) , ocean dynamics (see for NAO in Schöne et al 2003; see for AMOC in; Wanamaker et al 2012), hydrographic changes and ecosystem dynamics (Witbaard 1996;Witbaard et al 2003).…”