Ecological mechanisms can modify radiation effects in a key forest mammal of Chernobyl

Abstract

Nuclear accidents underpin the need to quantify the ecological mechanisms which determine injury to ecosystems from chronic low‐dose radiation. Here, we tested the hypothesis that ecological mechanisms interact with ionizing radiation to affect natural populations in unexpected ways. We used large‐scale replicated experiments and food manipulations in wild populations of the rodent, Myodes glareolus, inhabiting the region near the site of the Chernobyl disaster of 1986. We show linear decreases in breeding success with increasing ambient radiation levels with no evidence of any threshold below which effects are not seen. Food supplementation of experimental populations resulted in increased abundances but only in locations where radioactive contamination was low (i.e., below ≈ 1 μSv/h). In areas with higher contamination, food supplementation showed no detectable effects. These findings suggest that chronic low‐dose‐rate irradiation can decrease the stability of populations of key forest species, and these effects could potentially scale to broader community changes with concomitant consequences for the ecosystem functioning of forests impacted by nuclear accidents.

Towards solving a scientific controversy – The effects of ionising radiation on the environment

“…Conversely, others report significant impacts of radiation on wildlife at extremely low dose rates. For instance, significant reductions in invertebrate numbers over dose rates which are in the typical range for natural background exposures (Møller and Mousseau, 2009), LD50 values (the lethal dose required to kill 50% of exposed individuals) for butterfly larvae (Hiyama et al, 2012) below the commonly used generic 'predicted no effect dose rate' of 10 µGy h -1 (Andersson et al, 2009; see discussion in Copplestone and Beresford, 2014) and 'significant radiation effects' on bank vole populations at ambient dose rates of 1 µSv h -1 or less (Mappes et al, 2019). If such studies have been correctly conducted and interpreted, then the results would have implications for the system of radiation protection for both the environment and humans (Beresford and Copplestone, 2011).…”

The effect of chronic low-dose environmental radiation on organ mass of bank voles in the Chernobyl exclusion zone

“…rivers). As previous research has found no effect of environmental radiation on ground level plant coverage (0-50 cm), the most important vegetation variable for bank voles (Mappes et al 2019), no large differences in food sources among our trapping locations were not expected. We used Ugglan Special2 live traps (Grahnab, Sweden) baited with potato and sunflower seeds and distance between neighboring trapping sites was at least 1 km.…”

“…Reproductive costs in females could explain the smaller organ size, since bank vole females can have up to ten pups in one litter (Koskela et al 1998). A link between radiation and reproductive output was shown in a previous study where ambient radiation level was negatively correlated with female litter size (Lehmann et al 2016;Mappes et al 2019).…”

“…Decreased growth rate and smaller body size have indeed been observed in butterflies (Hiyama et al 2013) and delayed growth rate has been seen in monkey fetuses (Hayama et al 2017) in the contaminated areas of Fukushima. The bank vole litter sizes have been shown to decrease with increasing radiation in the CEZ (Mappes et al 2019), indicating some reproductional costs in contaminated sites. Our data suggest that low environmental radiation can induce changes in organ masses, particularly in organs with slow cell turnover rate.…”

“…Bank voles are widespread throughout Europe, found in both coniferous and deciduous forests (Ledevin et al 2010). Bank voles are the most abundant rodent species in the CEZ and can be found even in the most contaminated locations (Chesser et al 2000), however, the abundances decrease with increasing radiation in the capture locations (Mappes et al 2019). Bank voles have very variable diet from roots, plant stems and leaves to seeds, lichens and insects (Canova 1993).…”