Combining simulation modeling and stable isotope analyses to reconstruct the last known movements of one of Nature’s giants

The spatial ecology of rare, migratory oceanic animals is difficult to study directly. Where incremental tissues are available, their chemical composition can provide valuable indirect observations of movement and diet. Interpreting the chemical record in incremental tissues can be highly uncertain, however, as multiple mechanisms interact to produce the observed data. Simulation modeling is one approach for considering alternative hypotheses in ecology and can be used to consider the relative likelihood of obtaining an observed record under different combinations of ecological and environmental processes. Here we show how a simulation modeling approach can help to infer movement behaviour based on stable carbon isotope profiles measured in incremental baleen tissues of a blue whale (Balaenoptera musculus). The life history of this particular specimen, which stranded in 1891 in the UK, was selected as a case study due to its cultural significance as part of a permanent display at the Natural History Museum, London. We specifically tested whether measured variations in stable isotope compositions across the analysed baleen plate were more consistent with residency or latitudinal migrations. The measured isotopic record was most closely reproduced with a period of residency in sub-tropical waters for at least a full year followed by three repeated annual migrations between sub-tropical and high latitude regions. The latitudinal migration cycle was interrupted in the year prior to stranding, potentially implying pregnancy and weaning, but isotopic data alone cannot test this hypothesis. Simulation methods can help reveal movement information coded in the biochemical compositions of incremental tissues such as those archived in historic collections, and provides context and inferences that are useful for retrospective studies of animal movement, especially where other sources of individual movement data are sparse or challenging to validate.© 2019 Trueman et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited

Inter-annual variability in isotope and elemental ratios recorded in otoliths of an anadromous fish

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Geochemical Exploration 102 (2009): 181-186, doi:10.1016/j.gexplo.2008.10.001.Isotope ratios and elemental concentrations in otoliths are often used as natural tags to reconstruct migratory movements and connectivity patterns in marine and anadromous fishes. Although differences in otolith geochemistry have been documented among geographically separated populations, inter-annual variation within locations is less frequently examined. We compared otolith isotope (δ18O and 87Sr:86Sr) and elemental ratios (Sr:Ca and Ba:Ca) from several annual cohorts of juvenile American shad (Alosa sapidissima) in three rivers. These four geochemical signatures distinguished among river-specific populations of this species at both large and small geographic scales, with δ18O and 87Sr:86Sr generating the majority of multivariate variation. We found significant variation among years for all variables in two to three rivers. However, the magnitude of variability differed among ratios, with δ18O ratios showing substantial inter-annual shifts while 87Sr:86Sr ratios were relatively stable across years. Sr:Ca and Ba:Ca ratios also varied among years. These results imply that investigators using environmentally labile signatures must quantify geochemical signatures for each cohort of interest in order to confidently identify origins of migrants.Funding was provided by National Science Foundation grants to SRT (OCE-0215905 and OCE-0134998) and grants by the American Museum of Natural History Lerner-Gray Fund for Marine Research, SEASPACE, Inc., and the WHOI Ocean Life Institute to BDW

Regional age structure, human capital and innovation - is demographic ageing increasing regional disparities?

Demographic change is expected to affect labour markets in very different ways on a regional scale. The objective of this paper is to explore the spatio-temporal patterns of recent distributional changes in the workers age structure, innovation output and skill composition for German regions by conducting an Exploratory Space-Time Data Analysis (ESTDA). Beside commonly used tools, we apply newly developed approaches which allow investigating the space-time dynamics of the spatial distributions. We include an analysis of the joint distributional dynamics of the patenting variable with the remaining interest variables. Overall, we find strong clustering tendencies for the demographic variables and innovation that constitute a great divide across German regions. The detected clusters partly evolve over time and suggest a demographic polarization trend among regions that may further reinforce the observed innovation divide in the future

The backward-bending commute times of married women with household responsibility

The purpose of this paper is to examine theoretically and empirically whether the commute times of married women follow a backward-bending pattern with respect to wage rates. The existing literature has shown that married women tend to choose short commutes because of their relatively low wages combined with comparatively heavy household responsibilities. However, a workleisure model, which includes the simultaneous decision wives take regarding commute times and wage rates, suggests that married women employed in highly paid positions also undertake short commutes, while married women with wage rates in the middle range choose long commutes. These results suggest that the commute times of married women display a backward-bending pattern. Applying an instrumental variable strategy that accounts for the endogeneity of wage rates, the empirical results for employed married women in Japan appear to support this nding. Moreover, one of our results suggests that highly paid married women can still secure greater leisure time with short commutes, despite retaining a heavy load of domestic responsibilities.Working Paper, No.234, 2008.9.1版http://hdl.handle.net/10110/254

Ethnic Inequalities in Psychological Distress : A Population Data Linkage Study on the Pacific Island of Guåhån/Guam

Psychological distress and mental illness has been found to be elevated in migrant groups living in sovereign countries, as well as for indigenous people living under colonial or administrative rule. The north Pacific island of Guam is unusual in its ethnic composition as it has no majority ethnic group, has a large indigenous population and remains a territory of the U.S. This study aimed to identify ethnic differences in self-reported psychological distress between the main ethnic groups on Guam. The study uses a cross sectional design with data linkage methodology, drawing on the Guam Census and the Behavioral Risk Factor Surveillance System health survey for Guam. The results showed that the native Chamorro population had worse self-reported psychological distress (defined as a ‘mental health condition or emotional problem’) than White/Caucasians (OR 2.09, 95% CI 1.52–2.87), particularly for severe distress (OR 3.61, 95% CI 1.33–2.77). This relationship persisted even after adjusting for a wide range of socio-demographic and economic factors (OR 2.58, 95% CI 1.15–5.76). Other Pacific Islanders also had higher psychological distress compared to White/Caucasians, but this association was largely explained by the adjusted factors. The findings are discussed in terms of social and economic disadvantage for Pacific Island peoples on Guam, as well as the impact of colonial administration, disaffection, and lack of autonomy for the Chamorro of Guam. Recommendations are made to improve psychiatric treatment for these groups by considering wider socio-political factors in assessment and treatment, as well as broader implications for the national dialogue on self-determination.Peer reviewe