Establishing the limitations on using archived marine mammal samples for stable isotope analysis: an examination of differing preservation methods on tissues of harbor porpoise ( Phocoena phocoena ) and gray seal ( Halichoerus grypus )

The use of biological samples from museum and/or archive collections is common in stable isotope research, particularly for marine mammals. Yet, the temporal stability of isotopic values across various tissue types and the influence of different preservatives on these values are not fully understood, posing significant challenges for accurate data interpretation. Here we examine the impact of three different tissue preservation methods (DMSO, ethanol, freezing), on seven different tissues (blubber, heart, kidney, lung, liver, muscle, and skin) from both a harbor porpoise (Phocoena phocoena) and a gray seal (Halichoerus grypus) for stable isotope analysis in a 1‐year period. Our results demonstrate that storage in DMSO generates greater temporal variability in δ13C and δ15N for all tissue types, particularly in the first six months of storage. Furthermore, tissues stored in DMSO often exhibited lower δ13C and δ15N values compared to those stored frozen or in ethanol. This finding highlights a significant issue for studies utilizing tissues stored in DMSO, regardless of the storage duration. These results underscore the critical need for careful consideration of preservation methods in studies involving stored tissues, providing valuable insights for experimental design and management of tissue archives

Climate reconstruction from paired oxygen-isotope analyses of chironomid larval head capsules and endogenic carbonate (Hawes Water, UK) - Potential and problems

Temperature and the oxygen isotopic composition (δ18O) of meteoric water are both important palaeoclimatic variables, but separating their influences on proxies such as the δ18O of lake carbonates is often problematic. The large temperature variations that are known to have occurred in the northern mid-latitudes during the Late Glacial make this interval an excellent test for a novel approach that combines oxygen-isotope analyses of chironomid larval head capsules with co-occurring endogenic carbonate. We apply this approach to a Late Glacial lake sediment sequence from Hawes Water (NW England). Oxygen-isotope values in chironomid head capsules show marked variations during the Late Glacial that are similar to the oxygen isotope record from endogenic carbonate. However, summer temperature reconstructions based on the paired isotope values and fractionation between chironomids and calcite yield values between −20 and −4 °C, which are unrealistic and far lower than reconstructions based on chironomid assemblages at the same site. The composition of a limited number of samples of fossil chironomid larval head capsules determined using Pyrolysis gas-chromatography mass spectrometry indicates the presence of aliphatic geopolymers, suggesting that diagenetic alteration of the head capsules has systematically biased the isotope-derived temperature estimates. However, a similar trend in the isotope records of the two sources suggests that a palaeoclimate signal is still preserved

Cultural traditions across a migratory network shape the genetic structure of southern right whales around Australia and New Zealand

Fidelity to migratory destinations is an important driver of connectivity in marine and avian species. Here we assess the role of maternally directed learning of migratory habitats, or migratory culture, on the population structure of the endangered Australian and New Zealand southern right whale. Using DNA profiles, comprising mitochondrial DNA (mtDNA) haplotypes (500 bp), microsatellite genotypes (17 loci) and sex from 128 individually-identified whales, we find significant differentiation among winter calving grounds based on both mtDNA haplotype (F[subscript]ST = 0.048, Φ[subscript]ST = 0.109, p < 0.01) and microsatellite allele frequencies (F[subscript]ST = 0.008, p < 0.01), consistent with long-term fidelity to calving areas. However, most genetic comparisons of calving grounds and migratory corridors were not significant, supporting the idea that whales from different calving grounds mix in migratory corridors. Furthermore, we find a significant relationship between δ¹³C stable isotope profiles of 66 Australian southern right whales, a proxy for feeding ground location, and both mtDNA haplotypes and kinship inferred from microsatellite-based estimators of relatedness. This indicates migratory culture may influence genetic structure on feeding grounds. This fidelity to migratory destinations is likely to influence population recovery, as long-term estimates of historical abundance derived from estimates of genetic diversity indicate the South Pacific calving grounds remain at <10% of pre-whaling abundance.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Nature Publishing Group. The published article can be found at: http://www.nature.com/articles/srep1618

Changes in CO2 during ocean anoxic event 1d indicate similarities to other carbon cycle perturbations

Past greenhouse intervals of the Mesozoic were repeatedly punctuated by Ocean Anoxic Events (OAEs), major perturbations to the global carbon cycle and abrupt climate changes that may serve as relevant analogs for Earth’s greenhouse gas-forced climate future. The key to better understanding these transient climate disruptions and possible CO2 forced tipping-points resides in high-resolution, precise, and accurate estimates of atmospheric CO2 for individual OAEs. Here we present a high-temporal resolution, multi-proxy pCO2 reconstruction for the onset of mid-Cretaceous (Albian-Cenomanian Boundary) OAE1d. Coupling of pCO2 estimates with carbon isotopic compositions (δ13C) of charcoal, vitrain, and cuticle from the Rose Creek Pit (RCP), Nebraska, reveals complex phasing, including a lag between the well-documented negative δ13C excursion defining the onset of OAE1d and the CO2 increase. This lag indicates that increased CO2 or other C-based greenhouse gases may not have been the primary cause of the negative excursion. Our study reveals a pCO2 increase within the interval of the negative δ13C excursion, reaching a maximum of up to ~840 ppm (95% confidence interval -307 ppm/+167 ppm) toward its end. The reconstructed magnitude of CO2 increase (~357 ppm) is similar to that of Late Cretaceous OAE2 but of smaller magnitude than that of other major carbon cycle perturbations of the Mesozoic assessed via stomatal methods (e.g., the Toarcian OAE [TOAE], Triassic-Jurassic boundary event, Cretaceous-Paleogene Boundary event). Furthermore, our results indicate a possible shared causal or developmental mechanism with OAE1a and the TOAE

Changing environments during the Middle-Upper Palaeolithic transition in the eastern Cantabrian Region (Spain): direct evidence from stable isotope studies on ungulate bones

Environmental change has been proposed as a factor that contributed to the extinction of the Neanderthals in Europe during MIS3. Currently, the different local environmental conditions experienced at the time when Anatomically Modern Humans (AMH) met Neanderthals are not well known. In the Western Pyrenees, particularly, in the eastern end of the Cantabrian coast of the Iberian Peninsula, extensive evidence of Neanderthal and subsequent AMH activity exists, making it an ideal area in which to explore the palaeoenvironments experienced and resources exploited by both human species during the Middle to Upper Palaeolithic transition. Red deer and horse were analysed using bone collagen stable isotope analysis to reconstruct environmental conditions across the transition. A shift in the ecological niche of horses after the Mousterian demonstrates a change in environment, towards more open vegetation, linked to wider climatic change. In the Mousterian, Aurignacian and Gravettian, high inter-individual nitrogen ranges were observed in both herbivores. This could indicate that these individuals were procured from areas isotopically different in nitrogen. Differences in sulphur values between sites suggest some variability in the hunting locations exploited, reflecting the human use of different parts of the landscape. An alternative and complementary explanation proposed is that there were climatic fluctuations within the time of formation of these archaeological levels, as observed in pollen, marine and ice cores.This research was funded by the European Commission through a Marie Curie Career Integration Grant (FP7- PEOPLE-2012-CIG-322112), by the Spanish Ministry of Economy and Competitiveness (HAR2012-33956 and Ramon y Cajal-2011-00695), the University of Cantabria and Campus International to ABMA. Radiocarbon dating at ORAU was funded by MINECO-HAR2012-33956 project. J.J was supported initially by the FP7- PEOPLE-2012-CIG-322112 and later by a Marie Curie Individual Fellowship (H2020-MSCA-IF-2014-656122). Laboratory work, associated research expenses and isotopic analysis were kindly funded by the Max Planck Society to M.R