The effects of the organopollutant PCB 126 on bone density in juvenile diamondback terrapins (Malaclemys terrapin)

Abstract

Bone is a dynamic tissue with diverse functions including growth, structural support, pH balance and reproduction. These functions may be compromised in the presence of organopollutants that can alter bone properties. We exposed juvenile diamondback terrapins (Malaclemys terrapin) to 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126), a ubiquitous anthropogenic organochlorine, and measured organic content, apparent bone mineral density (aBMD) using radiography and computed tomography, and quantified bone microstructure using histological preparations of femora. PCB-exposed terrapins were smaller in total size. Skulls of exposed animals had a higher organic content and a skeletal phenotype more typical of younger animals. The femora of exposed individuals had significantly reduced aBMD and significantly more cortical area occupied by non-bone. Because bone is an integral component of physiology, the observed skeletal changes can have far-reaching impacts on feeding and locomotor performance, calcium reserves and ultimately life history traits and reproductive success. Additionally, we caution that measurements of bone morphology, density, and composition from field-collected animals need to account not only for relatedness and age, but also environmental pollutants.