This dataset contains diatom abundance (Valves g-1), fragments (%), and relative percentage of diatom species and associated standard error (%) from core MD07-3081. 51 samples, with a resolution of 0.1 to 1 ka, were analyzed for diatom content. For sediment processing and slide preparation, we followed the protocol described by Crosta et al., 2020. We calculated the associated error of each percentage based on the equation proposed by Patterson and Fishbein (1989). Chaetoceros spp. resting spores (CRS) were not identified at the species level. Due to their similar ecology, we grouped the species Thalassionema nitzschioides var. capitulata and Thalassionema nitzschioides var. lanceolata under the Thalassionema nitzschioides group, the species Shionodiscus trifultus and Shionodiscus frenguellii were grouped under the name of the Shionodiscus group because these species look very similar under the light microscope and have a similar ecology and distribution in subantarctic waters, Azpeitia tabularis var. tabularis and Azpeitia tabularis var. egrerius were combined into the Azpeitia tabularis group. Finally, Shionodiscus oestrupii var. oestrupii is referred hereafter to Shionodiscus oestrupii. Total diatom counts include Chaetoceros resting spores.

The financial support for this research was given by:1) French-Swedish project on SO VR-349-2012-6278, Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Laboratoire mixte CNRS-CEA-UVSQ, Bât 714, L'orme des Merisiers, 91190 Gif-sur-Yvette Cedex, France2) French INSU SEPORA project, Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Laboratoire mixte CNRS-CEA-UVSQ, Bât 714, L'orme des Merisiers, 91190 Gif-sur-Yvette Cedex, FranceWe also thank the LMC14 staff "Laboratoire de Mesure du Carbone-14", ARTEMIS national facility (LSCE (CNRS-CEA-UVSQ)-IRD-IRSN-MC) (Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Laboratoire mixte CNRS-CEA-UVSQ, Bât 714, L'orme des Merisiers, 91190 Gif-sur-Yvette Cedex, France), for the results obtained with the accelerator mass spectrometry method.