Crustose coralline algae as archives for understanding climate and environmental changes in Earth’s recent past

Abstract

If unabated, the continued anthropogenic release of carbon dioxide is expected to lead to warming and acidification of ocean waters, with widespread and detrimental impacts on marine ecosystems. The quantitative assessment of anthropogenic impacts on climate and ecosystems requires knowledge about natural long-term climate variability. However, instrumental records of oceanographic features are sparse and both spatially and temporally limited – particularly in the cold, harsh, and remote high-latitude regions. Therefore, we must rely on proxy information stored in shells and skeletons of long-lived organisms as archives of past climatic changes. Crustose coralline algae are a group of calcareous marine algae that form hard rock-like crusts on the shallow rocky seafloor. Coralline algae of the genus Clathromorphum are particularly well suited as paleoclimate archives because they are abundant and widely distributed in mid-to-high latitude oceans, exceptionally long-lived (up to 850 ±20 years), and form clear and distinct annual growth bands. Over the past decade, a number of different geochemical and microanalytical methods have been utilized to examine isotopes, trace element compositions, and growth structures within the algal skeleton. This wealth of proxy information spanning multi-centennial timescales has provided us with a better understanding of past oceanographic changes such as: sea surface temperature, salinity, shallow marine light dynamics, Arctic sea-ice cover, seawater chemistry – as well as their associations with large-scale climate oscillation patterns. In this talk I will present an overview of the crustose coralline algae and how they have been used as archives for understanding past climate and environmental changes in the Subarctic North Pacific and North Atlantic Oceans, as well as ongoing research in the Arctic.

Biography

Dr. Phoebe Chan is a VISTA Postdoctoral Fellow (Norwegian Academy of Science and Letters and Equinor) at the University of Bergen, Norway. She obtained her MSc in Geology and PhD in Earth Science from the University of Toronto in Canada. Dr. Chan’s research is focussed on high-resolution climate and environmental change in Arctic and Subarctic seas within the last millennium. Her work specializes in examining proxy records stored within annual growth bands of long-lived crustose coralline algae using geochemical and microanalytical techniques. Her most recent work includes developing novel proxies for reconstructing phytoplankton productivity, and using micro-computed tomography to measure structural changes in the algal skeleton related to ocean acidification.

Venue

Room 309, Steele Building (#03)