Biosedimentary systems in Arctic environments: Polar coralline algae

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In 2006, the northernmost coralline algal grounds were discovered at 80°30 N off Nordaustlandet during EPS Maria S. Merian Cruise 2/3. This site and several others around Svalbard were intensively documented and sampled with the manned submarine Jago. Polar coralline algae seem to be much more widespread in polar waters than previously thought, thus representing a unique polar carbonate factory. This proposal intends to (1) analyse the biotic assemblage and functioning of these poorly known biosedimentary system, (2) to testify the value of coralline algae to reconstruct historic environmental change (e.g., the ongoing Arctic wanning, is it true?) using dating and geochemical methods, and (3) to estimate a budget for photic polar carbonates. The Svalbardian coralline algal grounds will be compared with those from northern Norway, some 1000 km further south but still beyond the Polar Circle. This comparison helps to elucidate the influence of poleward increasing saisonality on calcifying organisms. From both areas (Norway and Svalbard) mid-Holocene rhodoliths are available and allows the analysis of palaeoclimatic studies, such as the amplitude of the Holocene climatic optimum with the present situation in a polar region.