Marine chemistry variation along Greenland's coastline indicated by chemical fingerprints in capelin (Mallotus villosus) otoliths

The small pelagic fish capelin (Mallotus villosus) is widely distributed in the Arctic, where it plays a central role in the marine food web as prey for numerous fish, birds, and mammals. Sustainable fisheries management advice for capelin that spawn in Greenland is non-existent due in part to a lack of biological information on population structure and spatial dynamics. This study provides a chemical baseline for investigations of migration and population structure of capelin and potentially other marine organisms in Greenlandic waters, using chemical tracers in otoliths from 549 spawning capelin, collected from 18 localities along Greenland's coastline. Abundances of 14 elements were measured in otolith edges, and geographic variations were demonstrated for Li, Ba, Sr, Pb, Mg, P, Zn, and Mn. Linear discriminant analysis identified chemical disparity between otoliths from three regions along the coastline. The west coast contains two chemically distinct zones – north and south of ∼68 °N – based primarily on distributions of Li and Ba as indicators of environmental variability. Two localities exhibit elevated levels of Mg, P, Zn, and Mn; elements that are typically regulated by physiological mechanisms. The results demonstrate the applicability of otolith chemistry as a tracer of physicochemical variation in an arctic marine environment undergoing rapid climatic changes.