The Stable Isotope Characteristics of Precipitation in the Middle East Highlighting the Link between the Köppen Climate Classifications and the δ18O and δ2H Values of Precipitation

The Middle East is faced with a water shortage crisis due to its semiarid and arid climate. In this paper, precipitation as an important part of the water cycle was evaluated in 43 stations across the Middle East using the stable isotope technique to study the parameters which influence the stable isotope content of precipitation. First, the stepwise regression model was applied to determine the main geographical and climatological factors affecting the stable isotopes in precipitation. Secondly, the stepwise model was also used to simulate the stable isotope values in precipitation. Furthermore, due to the notable climatic variations across the Middle East, the precipitation sampling stations were classified into six groups based on the Köppen climate zones. Significant variations in the stable isotope values of precipitation were observed in the stations of each climate zone. Finally, the Middle East meteoric water line was developed for the dry and wet periods based on the average stable isotopes in the studied stations. The developed lines showed a lower slope compared to the GMWL due to the higher air temperature and relative humidity in the Middle East compared to the average global conditions. To conclude, the stable isotope contents in precipitation showed significant temporal and spatial variations due to the notable climatic variations across the Middle East.

Pet or pest? Stable isotope methods for determining the provenance of an invasive alien species

The illegal pet trade facilitates the global dispersal of invasive alien species (IAS), providing opportunities for new pests to establish in novel recipient environments. Despite the increasing threat of IAS to the environment and economy, biosecurity efforts often lack suitable, scientifically-based methods to make effective management decisions, such as identifying an established IAS population from a single incursion event. We present a proof-of-concept for a new application of a stable isotope technique to identify wild and captive histories of an invasive pet species. Twelve red-eared slider turtles (Trachemys scripta elegans) from historic Australian incursions with putative wild, captive and unknown origins were analysed to: (1) present best-practice methods for stable isotope sampling of T. s. elegans incursions; (2) effectively discriminate between wild and captive groups using stable isotope ratios; and (3) present a framework to expand the methodology for use on other IAS species. A sampling method was developed to obtain carbon (δ13C) and nitrogen (δ15N) stable isotope ratios from the keratin layer of the carapace (shells), which are predominantly influenced by dietary material and trophic level respectively. Both δ13C and δ15N exhibited the potential to distinguish between the wild and captive origins of the samples. Power simulations demonstrated that isotope ratios were consistent across the carapace and a minimum of eight individuals were required to effectively discriminate wild and captive groups, reducing overall sampling costs. Statistical classification effectively separated captive and wild groups by δ15N (captive: δ15N‰ ≥ 9.7‰, minimum of 96% accuracy). This study outlines a practical and accessible method for detecting IAS incursions, to potentially provide biosecurity staff and decision-makers with the tools to quickly identify and manage future IAS incursions.

Pet or pest? Stable isotope methods for the early detection of invasive alien species

The illegal pet trade facilitates the global dispersal of invasive alien species (IAS), providing opportunities for new pests to establish in novel recipient environments. Despite the increasing threat of IAS to the environment and economy, biosecurity efforts often lack suitable, scientifically-based methods to make effective management decisions; such as identifying an established IAS population from a single incursion event. We present a new application of a stable isotope technique to identify wild and captive histories of an invasive pet species. Twelve red-eared slider turtles (Trachemys scripta elegans) from Australian incursions with putative wild and captive origins were analyzed to: (1) present best-practice methods for sampling T.s.elegans incursions; (2) effectively discriminate between wild and captive groups using stable isotope ratios; and (3) present a framework to expand the methodology for use on other IAS species. A sampling method was developed to obtain carbon (δ13C‰) and nitrogen (δ15N‰) stable isotope ratios from the keratin layer of the carapace (shells), which identify differences in dietary plant material and trophic level respectively. Both δ13C‰ and δ15N‰ exhibited the potential to distinguish between the wild and captive origins of the samples. Power simulations demonstrated that isotope ratios were consistent across the carapace, and a minimum of 8 individuals were required to effectively discriminate wild and captive groups, reducing overall sampling costs. Statistical classification effectively separated captive and wild groups by δ15N‰ (captive: δ15N‰ ≥ 9.7‰, minimum of 96% accuracy), which suggested that captive individuals consumed greater proportions of terrestrial meat than wild individuals. This study outlines a practical and accessible method for detecting IAS incursions, providing biosecurity staff and decision makers with the tools to quickly identify and manage future IAS incursions.

Anthropometry based Predictive Equations for Estimating Nigerian Women Percentage Body Fat using Stable Isotope Technique as Reference

The direct measurement of body composition using innovative non-or minimally-invasive technologies such as stable isotope technique, despite its reliability and precision remains a significant challenge.  This study was designed to develop predictive equations for estimating the percentage body fat of Nigerian women using isotope dilution (ISD) or gold standard technique (as in IAEA procedure) as reference and validated by bioelectrical impedance technique.The percentage body fats (% BF) of 173 Nigerian women (aged 18-55 yrs) were estimated using isotope dilution (ISD) or gold standard technique (as in IAEA procedure) as reference and validated by bioelectrical impedance technique. The skinfold thicknesses (mm) such as biceps, triceps, subscapular, suprailiac and abdominal were measured using skinfold langre callipers while body circumferences such as forearm, wrist, waist, abdominal and hip were measured using standard tape rule and in accordance with WHO guidelines. The subjects’ percentage body fat (%BF) ranged from 8.0 to 48.5. Generally, at 0.01 level of significance (Using Statistical Package for Social Scientists (SPSS), higher positive significant correlations were obtained between % BF by ISD and body circumferences (r=0.503-0.874) than skinfold thicknesses (r=0.503-0.739). Using forward selection regression procedure, three sex-specific based predictive equations for estimating %BF (incorporating subjects’ weight and body circumferences such as hip, abdominal and waist) were developed based on the subjects’ ethnic groups (Yoruba, Hausa and Ibos) with high R2 (0.853, 0.953 & 0.867) and low Pure errors (3.316, 2.791 & 2.324) respect. These equations provide easy way of measuring percentage body fat and are recommended for use in clinical or epidemiological settings in populations with similar ethnic background and in lieu of isotope dilution method.