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Exploring, exploiting and evolving diversity of aquatic ecosystem models: a community perspective
(2015)
Here, we present a community perspective on how to explore, exploit and evolve the diversity in aquatic ecosystem models. These models play an important role in understanding the functioning of aquatic ecosystems, filling in observation gaps and developing effective strategies for water quality management. In this spirit, numerous models have been developed since the 1970s. We set off to explore model diversity by making an inventory among 42 aquatic ecosystem modellers, by categorizing the resulting set of models and by analysing them for diversity. We then focus on how to exploit model diversity by comparing and combining different aspects of existing models. Finally, we discuss how model diversity came about in the past and could evolve in the future. Throughout our study, we use analogies from biodiversity research to analyse and interpret model diversity. We recommend to make models publicly available through open-source policies, to standardize documentation and technical implementation of models, and to compare models through ensemble modelling and interdisciplinary approaches. We end with our perspective on how the field of aquatic ecosystem modelling might develop in the next 5-10 years. To strive for clarity and to improve readability for non-modellers, we include a glossary.
Auxology has developed from mere describing child and adolescent growth into a vivid and interdisciplinary research area encompassing human biologists, physicians, social scientists, economists and biostatisticians. The meeting illustrated the diversity in auxology, with the various social, medical, biological and biostatistical aspects in studies on child growth and development.
Objective: We analyse temporal trends and regional variation among the most recent available anthropometric data from German conscription in the years 2008-2010 and their historical contextualization since 1956. Design/setting/subjects: The overall sample included German conscripts (N 13 857 313) from 1956 to 2010. Results: German conscripts changed from growing in height to growing in breadth. Over the analysed 54 years, average height of 19-year-old conscripts increased by 6.5 cm from 173.5 cm in 1956 (birth year 1937) to 180.0 cm in 2010 (birth year 1991). This increase plateaued since the 1990s (1970s birth years). The increase in average weight, however, did not lessen during the last two decades but increased in two steps: at the end of the 1980s and after 1999. The weight and BMI distributions became increasingly right-skewed, the prevalence of overweight and obesity increased from 11.6 % and 2.1 % in 1984 to 19.9 % and 8.5 % in 2010, respectively. The north-south gradient in height (north = taller) persisted during our observations. Height and weight of conscripts from East Germany matched the German average between the early 1990s and 2009. Between the 1980s and the early 1990s, the average chest circumference increased, the average difference between chest circumference when inhaling and exhaling decreased, as did leg length relative to trunk length. Conclusions: Measuring anthropometric data for military conscripts yielded year-by-year monitoring of the health status of young men at a proscribed age. Such findings contribute to a more precise identification of groups at risk and thus help with further studies and to target interventions.
The dual isotopes of deep nitrate as a constraint on the cycle and budget of oceanic fixed nitrogen
(2009)
We compare the output of an 18-box geochemical model of the ocean with measurements to investigate the controls on both the mean values and variation of nitrate delta N-15 and delta O-18 in the ocean interior. The delta O-18 of nitrate is our focus because it has been explored less in previous work. Denitrification raises the delta N-15 and delta O-18 of mean ocean nitrate by equal amounts above their input values for N-2 fixation (for delta N-15) and nitrification (for delta O-18), generating parallel gradients in the delta N-15 and delta O-18 of deep ocean nitrate. Partial nitrate assimilation in the photic zone also causes equivalent increases in the delta N-15 and delta O-18 of the residual nitrate that can be transported into the interior. However, the regeneration and nitrification of sinking N can be said to decouple the N and O isotopes of deep ocean nitrate, especially when the sinking N is produced in a low latitude region, where nitrate consumption is effectively complete. The delta N-15 of the regenerated nitrate is equivalent to that originally consumed, whereas the regeneration replaces nitrate previously elevated in delta O-18 due to denitrification or nitrate assimilation with nitrate having the delta O-18 of nitrification. This lowers the delta O-18 of mean ocean nitrate and weakens nitrate delta O-18 gradients in the interior relative to those in delta N-15. This decoupling is characterized and quantified in the box model, and agreement with data shows its clear importance in the real ocean. At the same time, the model appears to generate overly strong gradients in both delta O-18 and delta N-15 within the ocean interior and a mean ocean nitrate delta O-18 that is higher than measured. This may be due to, in the model, too strong an impact of partial nitrate assimilation in the Southern Ocean on the delta N-15 and delta O-18 of preformed nitrate and/or too little cycling of intermediate-depth nitrate through the low latitude photic zone.
The pace-of-life syndrome (POLS) hypothesis posits that life-history characteristics, among individual differences in behavior, and physiological traits have coevolved in response to environmental conditions. This hypothesis has generated much research interest because it provides testable predictions concerning the association between the slow-fast life-history continuum and behavioral and physiological traits. Although humans are among the most well-studied species and similar concepts exist in the human literature, the POLS hypothesis has not yet been directly applied to humans. Therefore, we aimed to (i) test predicted relationships between life history, physiology, and behavior in a human population and (ii) better integrate the POLS hypothesis with other similar concepts. Using data of a representative sample of German adolescents, we extracted maturation status for girls (menarche, n = 791) and boys (voice break, n = 486), and a set of health-related risk-taking behaviors and cardiovascular parameters. Maturation status and health-related risk behavior as well as maturation status and cardiovascular physiology covaried in boys and girls. Fast maturing boys and girls had higher blood pressure and expressed more risk-taking behavior than same-aged slow maturing boys and girls, supporting general predictions of the POLS hypothesis. Only some physiological and behavioral traits were positively correlated, suggesting that behavioral and physiological traits might mediate life-history trade-offs differently. Moreover, some aspects of POLS were sex-specific. Overall, the POLS hypothesis shares many similarities with other conceptual frameworks from the human literature and these concepts should be united more thoroughly to stimulate the study of POLS in humans and other animals. Significance statement The pace-of-life syndrome (POLS) hypothesis suggests that life history, behavioral and physiological traits have coevolved in response to environmental conditions. Here, we tested this link in a representative sample of German adolescents, using data from a large health survey (the KIGGs study) containing information on individual age and state of maturity for girls and boys, and a set of health-related risk-taking behaviors and cardiovascular parameters. We found that fast maturing girls and boys had overall higher blood pressure and expressed more risk-taking behavior than same-aged slow maturing girls and boys. Only some behavioral and physiological traits were positively correlated, suggesting that behavioral and physiological traits might mediate life-history trade-offs differently and not necessarily form a syndrome. Our results demonstrate a general link between life history, physiological and behavioral traits in humans, while simultaneously highlighting a more complex and rich set of relationships, since not all relationships followed predictions by the POLS hypothesis.
The possibility of an impact of global warming on the Indian monsoon is of critical importance for the large population of this region. Future projections within the Coupled Model Intercomparison Project Phase 3 (CMIP-3) showed a wide range of trends with varying magnitude and sign across models. Here the Indian summer monsoon rainfall is evaluated in 20 CMIP-5 models for the period 1850 to 2100. In the new generation of climate models, a consistent increase in seasonal mean rainfall during the summer monsoon periods arises. All models simulate stronger seasonal mean rainfall in the future compared to the historic period under the strongest warming scenario RCP-8.5. Increase in seasonal mean rainfall is the largest for the RCP-8.5 scenario compared to other RCPs. Most of the models show a northward shift in monsoon circulation by the end of the 21st century compared to the historic period under the RCP-8.5 scenario. The interannual variability of the Indian monsoon rainfall also shows a consistent positive trend under unabated global warming. Since both the long-term increase in monsoon rainfall as well as the increase in interannual variability in the future is robust across a wide range of models, some confidence can be attributed to these projected trends.