Sea ice has always been an important resource for Inuit: a place to hunt, a means of travel, a foundation for making a home. It has also played a necessary role in Earth systems as a cooling mechanism by reflecting solar radiation back to the atmosphere. However, since the industrial era, sea ice conditions have changed; current projections estimate ice-free summers in the Arctic by 2050. With less sea ice, more radiative heat is being absorbed by the ocean, which in turn melts more ice and reduces the globe’s ability to cool itself. Accordingly, scientists are working to predict future outcomes using satellite records (1978 – present). Though satellite records only extend 40 years, the integration of longer-term, high-resolution and cross-Arctic sea ice records can improve their accuracy.
Local, high-resolution and annual sea ice records that pre-date the satellite era have been produced through chemical and growth rate analyses of coralline red algae species, Clathromorphum compactum, from Labrador and Arctic Bay, Nunavut (Halfar et al. 2013). These algae live at shallow depths (10 – 20 m) on the rocky Arctic seafloor. As they grow, they form ‘tree ring-like’ annual layers in their calcified skeletons: layers that can record annual sea ice concentrations (Adey et al. 2013). When sea ice cover blocks out sunlight, algal growth is halted. Therefore, during years of high sea ice cover, growth rings will be thinner in comparison to years with less sea ice coverage. Further, the integration of various elements including magnesium and calcium in C. compactum’s hard skeleton are also dependent on sunlight (Williams et al. 2018). By combining annual magnesium to calcium ratio data and growth ring widths, growth and growth cessation periods can be identified, thereby recording local annual sea ice cover variability. A long-lived specimen of C. compactum can live up to 600 years, making it an indispensable multi-century sea ice proxy. Currently, there is a lack of records relating to cross-Arctic annual sea ice concentration prior to 1978, which would assist in predicting future sea ice conditions. In short, a network of C. compactum-derived sea ice records can aid in modelling future environmental outcomes in the Arctic.
Accordingly, we are proposing a field expedition assisted by SCUBA to collect coralline red algae, C. compactum, around Gjoa Haven, Cambridge Bay, and Anderson Bay, Nunavut. Collection locations were selected based on information gleaned from previous Arctic coralline red algae surveys and suspected habitat locations found through a review of the Canadian Hydrographic Service’s multi-beam radar imagery. Furthermore, these locations are significant due to their association to modern and historic Inuit settlements and European exploration expeditions (e.g., Amundsen and Ross expeditions) and shipwrecks (i.e., HMS Erebus and HMS Terror of the Franklin Expedition). We are also proposing to work with the Canadian High Arctic Research Station and local community members to reach dive sites by charting vessels operated by SCUBA-experienced crew. In addition, we plan to conduct a series of interviews facilitated with the help of the Hunters and Trappers Association to provide information on past local sea ice conditions, and on experiences living in a changing sea ice landscape.
Results will produce high-resolution records of local sea ice conditions, which can aid in modelling future environmental outcomes in the Arctic, and inform policy makers on how to best manage sea ice-related issues. Furthermore, these data can provide historical regional sea ice information that can shed light on how sea ice affected shipwrecking events, which is currently poorly understood.
Adey, W. H., Halfar, J., and Williams, B., 2013, The Coralline Genus Clathromorphum Foslie emend. Adey: Biological, Physiological, and Ecological Factors
Controlling Carbonate Production in an Arctic-Subarctic Climate Archive: Washington D.C., Smithsonian Institution Scholarly Press, p. 41.
Halfar, J., Adey, W. H., Kronz, A., Hetzinger, S., Edinger, E. and Fitzhugh, W.W., 2013, Arctic sea-ice decline archived by multicentury annual-resolution record from crustose coralline algal proxy: Proceedings of the National Academy of Sciences of the United States of America, v. 110, no. 49, p. 19737-19741.
Williams, S., Adey, W.H., Halfar, J., Kronz, A., Gagnon, P., Bélanger, D., & Nash, M., 2018, Effects of light and temperature on Mg uptake, growth, and calcification in the proxy climate archive Clathromorphum compactum: Biogeosciences, v. 15, no. 19, p. 5745-5759.