Disentangling environmental drivers of subarctic dinocyst assemblage compositional change during the Holocene

• Published in: Climate of the Past
• Main Authors: Hohmann, Sabrina, Kucera, Michal, de Vernal, Anne
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2023
• Subjects: article; Verlagsveröffentlichung; Baffin Bay; Baffin; Subarctic
• Online Access: https://doi.org/10.5194/cp-19-2027-2023; https://noa.gwlb.de/receive/cop_mods_00069544; https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00067926/cp-19-2027-2023.pdf; https://cp.copernicus.org/articles/19/2027/2023/cp-19-2027-2023.pdf

Analysis of compositional changes in fossil organic-walled dinoflagellate cyst (dinocysts) assemblages is a widely used tool for the quantitative reconstruction of past environmental parameters. This approach assumes that the assemblage composition is significantly related to the reconstructed environmental parameter, which requires an independent correlation between the assemblage and the variable, meaning that the variable explains a dimension of the assemblage variance that is not also explained by other parameters. Theoretically, dinocyst assemblages can be used to reconstruct multiple environmental variables. However, there is evidence that primary and subordinate drivers for assemblage compositions regionally differ, and it remains unclear whether a significant relationship to specific parameters in the present ocean always implies that this relationship is significant in fossil assemblages, questioning if past changes in these multiple parameters can be reconstructed simultaneously from fossil assemblages. Here, we analysed a local subset of the Northern Hemisphere dinocyst calibration dataset (n=1968), including samples from the Baffin Bay area (n=421), and evaluated the benefits of a local versus a more regional or global calibration for the environmental reconstruction of Baffin Bay oceanography during the Holocene. We determined the dimensionality of the dinocyst ecological response and identified environmental drivers in the Baffin Bay area for the modern dataset. We analysed four existing Holocene records along a north–south transect in the area and evaluated the statistical significance of downcore reconstructions by applying the local and global datasets with different techniques: the modern analogue technique (MAT), the weighted average partial least square (WA-PLS) and maximum likelihood (ML). We evaluated reconstructions tested as significant in light of the existing state of knowledge about West Greenland's Holocene palaeoceanography. Our analyses imply that present-day and Holocene dinocyst ...