Trace element accumulation in the shell of the Arctic cirriped Balanus balanus

Barnacles are widespread and abundant inhabitants of rock surfaces in the intertidal zone, providing considerable contributions to the formation of carbonate sediments. The main goal of this study was to test two hypotheses: (1) the chemical composition of the Balanus balanus shell is mostly controlled biologically, and environmental factors have only minor influences, and (2) the chemical composition of B. balanus shells does not vary with size. To test these hypotheses, samples were collected in two fjords from two depths. This study revealed site-related differences in shell chemistry, although no variability in shell chemical compositions was detected between the depths and among the size categories. Barnacle shell plates had different accumulation patterns for different trace elements (Mg, S, Sr), with the operculum as the most distinctive shell plate. As those plates are precipitated under the same environmental conditions, the different accumulation patterns may indicate biological control of element uptake in cirripedes. We suggest that the specific chemical composition of the operculum may be related to the required mechanical properties of this shell part, and thus, it is likely that this organism regulates accumulation patterns within its shell, because such regulation increases its adaptive properties. Our results supported both presented hypotheses.