Ecogeochemistry in a changing Arctic Linking trace elements in the environment to the health of ungulate wildlife

To understand the health of large wildlife it is a central question to determine the availability of trace elements in the environment and their subsequent distribution within biota (including the potential alignment between trace element concentrations and health biomarkers). This is especially the case for the iconic and pre-historic muskoxen (Ovibos moschatus) which, due to climate-induced environmental effects and increased anthropogenic perturbations, are currently facing an unprecedented threat towards its survival. To ensure informed conservation strategies and sustainable environmental management, detailed and consistent information on ecosystem and population health is key. Yet in remote and inaccessible areas, such as the high-Arctic, monitoring of wildlife health is often logistically and financially challenging. Additionally, the use of traditional sampling methods to infer wildlife health (i.e. collection of liver or serum samples) are often constrained as they require invasive approaches or rely on hunted animals or carcasses (either of which is impractical for remote, endangered, or declining populations). As such, there is a need to develop novel, non-invasive methods to serve as an indicator of individual health and population dynamics to monitor and predict population trends in years between wildlife surveys. In a recently published pilot study (Mosbacher et al., 2022) we show that wool from muskoxen can act as a promising tool to detect deficiency of essential elements, which in turn could be linked to wildlife health on an individual level, ultimately translating into population-level demographic rates. While the use of hair/wool as a non-invasive monitoring tool to evaluate wildlife health certainly has potential, the distribution and coherence in concentrations of trace elements from the environment (soil and vegetation) to various tissues in the animal (e.g. blood, liver, muscle, spleen, hair), as well its linkages to the overall health status of the animal, are still largely unexplored. A better understanding of the environment biota wildlife health linkage is therefore needed before this non-invasive diagnostic tool can be used reliably to monitor the health status of wildlife populations. Using TQ-ICP-MS and IRMS, we analyzed the trace element composition (Se, Cu, Zn, Mo, Pb, Cd, Hg) and stable isotopes (13C 15N) in hair, feed and feces from wild, captive and culled muskoxen and assessed how these concentrations links to those in other internal tissues (blood, liver, muscle, kidney, spleen) as well as to the general health status of the animal (e.g. body condition score, serum analysis) and to the geochemical landscape in which they reside. Our initial results indicate that levels of essential elements appear relatively similar between wild and captive animals, whereas non-essential elements were higher in the wild populations. Further, health biomarkers such as SAA and cortisol also indicates that the captive animals appear to be in a generally better state than the wild animals, although further tests are needed to confirm this. Although preliminary, our results still highlight the central role trace elements play in the overall health of large Arctic wildlife on both individual and population level, and the important link between environmental ecogeochemistry and wildlife health.