Heavy metal content in the femora of yellow-necked mouse (Apodemus flavicollis) and wood mouse (Apodemus sylvaticus) from different types of polluted environment in Slovakia

Heavy metal content in the femora of yellow-necked mouse (Apodemus flavicollis) and wood mouse (Apodemus sylvaticus) caught in different polluted biotopes of a low hill level in Slovakia (Novaky and Kolinany) was investigated in the present study. Length, weight and histological structure of mouse bones have also been analysed. According to our results, higher concentrations of Cd, Ni, Fe, Cu and Zn were detected in the femora of A. flavicollis from Kolinany area. Similarly, we observed higher concentrations of Ni, Fe, Cu and Zn in the bones of A. sylvaticus trapped at the same biotope. Significant differences were observed for concentrations of Ni and Zn in both species (P < 0.05). The measured values for bone length and bone weight were higher in yellow-necked mice and wood mice from Novaky locality (P < 0.01). Histological observation of thin sections from femora of A. flavicollis and A. sylvaticus revealed an outer and inner non-vascular lamellar layer around a poorly developed reticular layer. We did not identify demonstrable changes in qualitative histological characteristics of the femora between the mice (A. flavicollis and A. sylvaticus separately) from different types of polluted environment. Also, no statistically significant differences for all the measured variables of primary osteons’ vascular canals were observed. Correlation analysis in yellow-necked mouse showed high positive relation between bone weight and bone length (r = 0.66), area and perimeter (r = 0.87) and perimeter and maximum diameter (r = 0.87). In wood mouse, high positive correlation between bone weight and bone length (r = 0.80), area and perimeter (r = 0.72), area and maximum diameter (r = 0.66) and perimeter and maximum diameter (r = 0.74) was found. Our results demonstrate slightly elevated accumulation of some heavy metals in the femora of yellow-necked mouse and wood mouse from Kolinany biotope and thus give an evidence of a contamination of the environment.