Seasonal shift of diet in bank voles explains trophic fate of anthropogenic osmium?

Abstract

Diet shifts are common in mammals and birds, but little is known about how such shifts along the food web affect contaminant exposure. Voles are staple food for many mammalian and avian predators. There is therefore a risk of transfer of contaminants accumulated in voles within the food chain. Osmium is one of the rarest earth elements with osmium tetroxide (OsO) as the most toxic vapor-phase airborne contaminant. Anthropogenic OsO accumulates in fruticose lichens that are important winter food of bank voles (Myodes glareolus). Here, we test if a) anthropogenic osmium accumulates in bank voles in winter, and b) accumulation rates and concentrations are lower in autumn when the species is mainly herbivorous. Our study, performed in a boreal forest impacted by anthropogenic osmium, supported the hypotheses for all studied tissues (kidney, liver, lung, muscle and spleen) in 50 studied bank voles. In autumn, osmium concentrations in bank voles were even partly similar to those in the graminivorous field vole (Microtus agrestis; n=14). In autumn but not in late winter/early spring, osmium concentrations were generally negatively correlated with body weight and root length of the first mandible molar, i.e. proxies of bank vole age. Identified negative correlations between organ-to-body weight ratios and osmium concentrations in late winter/early spring indicate intoxication. Our results suggest unequal accumulation risk for predators feeding on different cohorts of bank voles.

Hungry for fruit? – A case study on the ecology of middle Miocene Moschidae (Mammalia, Ruminantia)

“…From what we know on climate and environmental conditions in Central and Western Europe during the middle Miocene, and especially for the here studied localities (see discussion below for more details), we can assume that lichens were also present in these ecosystems, considering the distribution pattern of lichens in modern ecosystems, (e.g. from regions with a Mediterranean climate in Italy [Nimis & Tretiach 1995;Zedda 2002;Thüs & Licht 2006] conditions (no indications for temperatures below zero, nor for snow cover, or a pronounced dry season) still allowed a sufficient supply of nutrient richer diets all year round, lichens were assumedly less relevant in the diet of Miocene herbivores from this realm, as lichens often comprise mainly a fall-back resource during winter (Grueter et al 2009;Xiang et al 2012;Zhao et al 2015;Ecke et al 2018) (information on lichens: pers. comm.…”

Eco-epidemiological screening of multi-host wild rodent communities in the UK reveals pathogen strains of zoonotic interest

“… Healing et al, 1980 ; Kilonzo et al, 2013 ), which was in agreement with our findings (see also Swiecicka et al, 2003 ; Kozak et al, 2009 ). The presence of the bacterium may be related to gut microbiota variations due to diet seasonality ( Ecke et al, 2018 ; Gebczynska, 1983 ; Hansson, 1979 , 1985 ). No individuals were found infected by M. microti , likely due to the absence of lesions to the gastro-intestinal tract ( Burthe et al, 2008 ; Cavanagh et al, 2002 ; Kipar et al, 2013 ).…”

Three-way relationships between gut microbiota, helminth assemblages and bacterial infections in wild rodent populations

“…In the opposite, enterotype 2 is characterized by families (namely, Lactobacillae and Eggerthellaceae) that can be involved in the digestion of fermented food (e.g., rodent food store over winter), and insect skeleton (see refs in Maurice et al ., 2015) or in the degradation of polyphenol (Rodriguez-Daza et al ., 2020). All these aliments have varying nutritional and chemical composition and may be part of bank vole diet (Ecke et al ., 2018). The fraction of these different types of resources in bank vole diet may vary with resource preference or availabilities, reproductive status, sampling date and location (e.g., Maurice et al ., 2015).…”