Linking North Atlantic Climate Dynamics with Shell Growth and Geochemistry in Northern Norway

Abstract:

Very few long-term, continuous, high-resolution records of marine environmental conditions, such as seawater temperature and/or salinity, exist within the Arctic, hence, proxy-based records are needed to fully elucidate past marine climatic conditions. Our study uses the long-lived marine bivalve proxy, Arctica islandica, to investigate the impacts of large-scale climate variability on shell growth and geochemistry in northern Norway. A major goal of this work is to use the information stored in shell-based records as a proxy for regional ocean climate variability. The islands of Ingøy and Rolvsøy off northern Norway are located at the boundary between the Barents and Norwegian Seas, proximal to one of the main pathways of Atlantic water entering the Barents Sea, namely, the eastern branch of the North Atlantic Current. A master shell growth chronology constructed from nine shells documents 100 years of synchronous shell growth at Ingøy. Combining growth increment width and oxygen isotope data collected from annual increments yields an annually resolved, multi-proxy record of environmental conditions. A relatively strong inverse relationship (r = - 0.7) is observed between the shell-based multiproxy record and North Atlantic sea surface temperatures. The spatial pattern of correlation resembles that of the North Atlantic Current, indicating that large-scale ocean surface current dynamics play a role in regulating ecosystem processes and thus shell growth in northern Norway. This transfer function will serve the basis for hindcasting seawater temperatures from this location. Ongoing work includes the development of the master shell chronology for the past several centuries.