Human burials from the cemetery at the Rounala church, northern Sweden, were radiocarbon (C-14) dated to shed light on the use of the cemetery. Carbon, nitrogen and sulfur stable isotope analysis of bone collagen from 19 distinct individuals indicated that these individuals had a mixed diet consisting of freshwater, marine and terrestrial resources. Dietary modeling using FRUITS was employed to calculate the contributions of the different resources for each individual. These data were then used to calculate individual Delta R values, taking into account freshwater and multiple marine reservoir effects, the latter caused by Baltic and Atlantic marine dietary inputs, respectively. C-14 dating of tissues from modern freshwater fish species demonstrate a lack of a freshwater reservoir effect in the area. Two OxCal models were used to provide endpoint age estimates. The calibrated data suggest that the site's cemetery was most likely in use already from the 14th century, and perhaps until at least the late 18th century.

Due to the marine reservoir effect, radiocarbon dates of marine samples require a correction. Marine reservoir effects, however, may vary among different marine species within a given body of water. Factors such as diet, feeding depth and migratory behaviour all affect the ¹⁴C date of a marine organism. Moreover, there is often significant variation within single marine species. Whilst the careful consideration of the ΔR values of a single marine species in a given location is important, so too is the full range of ΔR values within an ecosystem. This paper illustrates this point, using a sample pairing method to estimate the reservoir effects in 17 marine samples, of eight different species, from the archaeological site of Ekven (Eastern Chukotka, Siberia). An OxCal model is used to assess the strength of these estimates. The marine reservoir effects of samples passing the model range from ΔR (Marine20) = 136 ± 41–ΔR = 460 ± 40. Marine reservoir effect estimates of these samples and other published samples are used to explore variability in the wider Bering Strait region. The archaeological implications of this variability are also discussed. The calibrating of ¹⁴C dates from human bone collagen, for example, could be improved by applying a dietary relevant marine reservoir effect correction. For humans from the site of Ekven, a ΔR (Marine20) correction of 289 ± 124 years or reservoir age correction of 842 ± 123 years is suggested. 

Marine reservoir effects (MRE) have the potential to increase the dating uncertainty of humans incorporating marine resources into their diets. Here we attempt a novel dental wiggle-match model to reduce dating uncertainty of seven individuals from the Resmo megalithic tomb (Öland, Sweden) and to test whether this model can be used to calculate MRE from a single tooth. Previous stable isotope ratio studies of these individuals demonstrated that their diets changed, between more or less marine protein, during the early years of their lives. Several incremental samples of dentine from each individual were subjected to radiocarbon dating and stable isotope ratio analysis. An OxCal model was designed that makes use of the known formation sequence of human teeth to reduce overall dating uncertainty. The new dental wiggle-match model is able to reduce overall dating uncertainty in all of the sampled individuals compared to more conventional 14C calibration methods. A utility of the dental wiggle model to estimate marine reservoir effects without associated faunal material is also demonstrated, with promising results.