Coralline algae as recorders of environmental change

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Quantifying the role and contribution of the world's oceans in past, present, and future global change is an essential goal in climate and paleoenvironmental studies. Although the global oceans influence climate greatly, the marine environment is substantially underrepresented in key climate assessment reports, especially during the last millennium. Over the past decades multicentury climate time series have emerged from tropical corals, and more recently from mid-latitude long-lived bivalves. However, subarctic and arctic proxy archival records are sparse. In order to fill this gap, a number of studies have demonstrated that mid- and high-latitude crustose coralline algae are an emerging extratropical marine environmental archive as they are amongst the longest lived shallow marine calcified organisms with life spans of several hundred years. More importantly, coralline algae occur in subarctic and arctic latitudes, both in the Pacific and Atlantic, where other high-resolution century-scale marine environmental proxies are non-existent. Hence, coralline algae have recently started to fill an important niche in marine paleoenvironmental proxy research, with several decadally to seasonally-resolved multicentury climate reconstructions published to date. This proposal will address two key themes to be answered using coralline proxy archives: A) Recently collected coralline algae from central and northern Labrador will be used to provide the first >500 year record of Labrador Current temperature and salinity variability and related climate oscillations in the northwestern Atlantic - a region where poorly understood climate and oceanographic changes have had a dramatic impact on ecosystems and fishery yields. B) Ongoing ocean acidification has been shown to potentially have a detrimental impact on the skeletons of calcareous plants and animals such as shellfish and corals. This is especially true in cold-water regions such as the subarctic North Pacific and northwest Atlantic, which are predicted to be amongst the first negatively affected by a decreasing ocean pH. Coralline algae from both oceans will be analyzed for temporal changes in skeletal structure and elemental composition, and as a proxy for reconstructing ocean pH over several centuries.