An Assessment of Marine Reservoir Corrections for Radiocarbon Dates on Walrus from the Foxe Basin Region of Arctic Canada

Abstract

Archaeological sites in the Canadian Arctic often contain substantial quantities of marine mammal bones and in some cases completely lack terrestrial mammal bones. A distrust of radiocarbon (14C) dates on marine mammal bones among Arctic archaeologists has caused many sites to be insufficiently dated. The goal of this study was to investigate the marine reservoir effect on Atlantic walrus in the Foxe Basin region of the Canadian Arctic through a two-pronged approach: dating of live-harvested specimens of known age collected prior to AD 1955 and dating of pairs of animal remains (walrus and caribou) from stratigraphically contemporaneous levels within archaeological features. 14C dates on pre-bomb, live-harvested walrus indicate that a ΔR value of 160±50 yr be used in calibrating dates on walrus from this region. These results differed significantly from a similar set of pre-bomb mollusks, which argues against applying mollusk-based corrections to marine mammals. The results of comparative dating of caribou and walrus from archaeological features provided maximum estimates of reservoir ages that were more varied than the directly measured ages. Although about half of inferred ΔR values overlap the museum specimen results, the others indicate that the assumption of contemporaneity does not hold true.

Zinc isotopes from archaeological bones provide reliable trophic level information for marine mammals

“…Relative differences in the consumption of higher and lower trophic level prey alone are unlikely to explain the Δ 15 N U. maritimus − P. hispida variability. As P. hispida bones are the most abundant fauna remains in all archaeological sites analysed herein 30 , 34 , 35 , it stands to reason that they were a similarly important food item for the archaeological U. maritimus populations as they are today 38 , 39 . Therefore, we expect even substantial differences in P. hispida trophic levels among sites to have only a small effect on Δ 15 N U. maritimus − P. hispida .…”

“…Both species have a circumpolar Arctic distribution and are abundant throughout the Arctic today 32 , 33 . Particularly, P. hispida remains are frequently found in archaeological assemblages with a large temporal and spatial range 30 , 34 , 35 .…”

Predicting sample success for large‐scale ancient DNA studies on marine mammals

“…In northern Norway, bone material typically shows better preservation when deposited in shell sands (Hodgetts, 1999). Finally, samples from archaeological sites can experience surface exposure during periods of site reoccupation when deposits become disturbed, as described for the Canadian Arctic (Dyke et al, 2018; Habu & Savelle, 1994; Savelle & Habu, 2004).…”

Advantages of zinc isotopes as a new dietary proxy in marine ecology

“…Both species have a circumpolar Arctic distribution and are abundant throughout the Arctic today 45,46 . Particularly, P. hispida remains are frequently found in archaeological assemblages with a large temporal and spatial range 43,47,48 . Studying the isotopic composition of high trophic level predators such as U. maritimus and P. hispida has the advantage of their tissues' composition dampening the effects of short-term environmental variation.…”