Multi-proxy study of primary production and paleoceanographical conditions in northern Baffin Bay during the last centuries

• Multi-proxy reconstructions of sea-surface conditions near the North Water polynya
• Slight warming accompanied by an increase in primary production after 1860 CE
• No direct link observed between the amount of IP25 in sediments and the sea-ice cover reconstructions.
• IP25 seems to be sensitive to the primary production in association with sea-ice.
• Ecosystem dominated by diatoms and sea-ice conditions limit primary production.

As polynyas are often used around the globe as a window on tomorrow's marine polar ecosystems, this study presents reconstructions of primary production and sea-surface conditions near the North Water polynya, since ~ 1560 CE from palynological, isotopic and biomarker analyses of a sediment core. Quantitative reconstructions of sea-surface conditions (temperature, sea-ice cover and production) were derived from the Modern Analogue Technique (MAT) applied to dinoflagellate cyst assemblages. Production was also qualitatively estimated from the stable isotope composition of organic carbon and nitrogen and the concentration of organic biomarkers (IP25, dinosterols). The results show relatively stable oceanographic conditions but suggest a slight warming accompanied by an increase in productivity after 1860 CE. The comparison of MAT reconstructions and the organic biomarker data suggests that IP25 provides information about primary production associated with sea-ice but does not unequivocally reflect sea-ice concentration in this regional setting, which is marked by dense seasonal sea ice except during the short summer season.