Abstract
Fluxes of carbon, nitrogen, and water between ecosystem components and organisms have great impacts across levels of biological organization. Although much progress has been made in tracing carbon and nitrogen, difficulty remains in tracing water sources from the ecosystem to animals and among animals (the “water web”). Naturally occurring, non-radioactive isotopes of hydrogen and oxygen in water provide a potential method for tracing water sources. However, using this approach for terrestrial animals is complicated by a change in water isotopes within the body due to differences in activity of heavy and light isotopes during cuticular and transpiratory water losses. Here we present a technique to use stable water isotopes to estimate the mean mix of water sources in a population by sampling a group of sympatric animals over time. Strong correlations between H and O isotopes in the body water of animals collected over time provide linear patterns of enrichment that can be used to predict a mean mix of water sources useful in standard mixing models to determine relative source contribution. Multiple temperature and humidity treatment levels do not greatly alter these relationships, thus having little effect on our ability to estimate this population-level mix of water sources. We show evidence for the validity of using multiple samples of animal body water, collected across time, to estimate the isotopic mix of water sources in a population and more accurately trace water sources. The ability to use isotopes to document patterns of animal water use should be a great asset to biologists globally, especially those studying drylands, droughts, streamside areas, irrigated landscapes, and the effects of climate change.
Highlights
Ecologists have long sought to trace fluxes of materials and energy within and among ecosystems [1,2,3,4]
It has been documented that H. antelucana greatly alter their rates of consumption of G. alogus based on free water availability [9]
We found a close match between fitted cricket regression lines in both singlesource experiments and the mean value of sources, with distances between these lines and sources differing by less than two parts per mil (Figure 2; Figure 3; Table 3)
Summary
Ecologists have long sought to trace fluxes of materials and energy within and among ecosystems [1,2,3,4]. The magnitudes of these fluxes are of great importance to studies of biogeochemistry [5], physiological ecology [6], population fluctuations [7], and global change [8]. While much progress has been made in measuring fluxes of energy or nutrients to and between organisms [6], studies of water webs (as opposed to food webs) [9] are hindered by a difficulty in measuring the relative use of water sources by animal populations [10,11]. Cost and time-effective methods of examining water sources for a suite of animals across space or time are greatly needed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
