ALBERT

Description: Planktic foraminifera census data have been used to reconstruct past temperatures through transfer functions, as well as changes in ocean ecosystems, chemistry and circulation. Here we present new multinet, plankton net and core-top census data from 20 sites in the Subpolar North Pacific. We combine these with previous data to provide an up to date compilation of North Pacific planktic foraminifera assemblage data. Our compilation is used to define 6 faunal zones: the subpolar zone; transitional zone; upwelling zone; subtropical zone; east equatorial zone; west equatorial zone; based on the distribution of 10 major species of planktic foraminifera. Two species of planktic foraminifera Neogloboquadrina pachyderma and Globigerina bulloides provide the basis for many subpolar paleo-reconstructions. Through the analysis of new multinet and CTD data we find that G. bulloides and N. pachyderma are predominantly found within 0-50 m of the water column and coincide with high food availability. N. pachyderma also shows a strong temperature control and can thrive in food poor waters where temperatures are low. Both species bloom seasonally, particularly during the spring bloom of March to June, with G. bulloides exhibiting greater seasonal variation. We suggest that percentage abundance of N. pachyderma in paleo-assemblages can be used to assess relative changes in past temperature, with G. bulloides abundance more likely to reflect changes in food availability. By comparing our core-top and multinet data, we also find a dissolution bias of G. bulloides over N. pachyderma in the North Pacific, which may enrich assemblages in the latter species.

Description: During the past 40,000 years, global climate has moved into and out of a full glacial period, with the deglaciation marked by several millennial-scale rapid climate change events. Here we investigate the ecological response of deep-sea coral communities to both glaciation and these rapid climate change events. We find that the deep-sea coral populations of Desmophyllum dianthus in both the North Atlantic and the Tasmanian seamounts expand at times of rapid climate change. However, during the more stable Last Glacial Maximum, the coral population globally retreats to a more restricted depth range. Holocene populations show regional patterns that provide some insight into what causes these dramatic changes in population structure. The most important factors are likely responses to climatically driven changes in productivity, [O2] and [CO3]2-.

Description: The data consist of ~600 U-Th ages of scleractianian cold-water corals dated by laser ablation and isotope dilution methods covering the last 150,000 years. The corals are from three locations: Reykjanes Ridge (57°N to 61°N, 28°W to 33°W); Tropic Seamount (23°55'N, 20°45'W); and the East Equatorial Atlantic from Carter (9°N, 21°W) and Knipovich seamounts (5°N, 27°W). The samples were collected with ROV and dredges during the cruises: CE0806 in 2008 (Reykjanes Ridge); JC094 in 2013 (Equatorial Atlantic); and JC142 in 2016 (Tropic Seamount). Additionally, a compilation of ~750 U-Th and 14C ages of scleractianian cold-water corals from the Northeast Atlantic Ocean is presented. The complete dataset is used to investigate the temporal and spatial coral distribution at Northeast Atlantic Ocean and the relation with past climatic events.

Description: Atmospheric dust is a primary source of iron (Fe) to the open ocean, and its flux is particularly important in the high nutrient, low chlorophyll (HNLC) Southern Ocean where Fe currently limits productivity. Alleviation of this Fe limitation in the Subantarctic Zone of the Atlantic by increased dust-borne Fe supply during glacial periods has been shown to increase primary productivity. However, previous work has found no such increase in productivity in the Pacific sector. In order to constrain the relative importance of Southern Ocean Fe fertilization on glacial-interglacial carbon cycles, records of dust fluxes outside of the Atlantic sector of the Southern Ocean at the Last Glacial Maximum (LGM) are required. Here we use grain size and U-series analyses to reconstruct lithogenic and CaCO3 fluxes, and Nd, Sr and Pb isotopes to ascertain the provenance of terrigenous material delivered to four deep-water cores in the SW Pacific Ocean over the last ~30kyr. We find evidence for an increase in the relative proportion of fine-grained (0.5-12 µm) terrigenous sediment and higher detrital fluxes during the LGM compared to the Holocene. The provenance of the LGM dust varied spatially, with an older, more "continental" signature (low εNd, high 87Sr/86Sr) sourced from Australia in the northern cores, and a younger, more volcanogenic source in the southern cores (high εNd, low 87Sr/86Sr), likely sourced locally from New Zealand. Given this increase in lithogenic flux to the HNLC subantarctic Pacific Southern Ocean during the LGM, factors besides Fe-supply must have regulated the biological productivity here.

Description: U-series ages of deep-sea corals from east Equatorial Atlantic and Reykjanes Ridge defined by laser ablation method. Depths of east Equatorial Atlantic corals was retrieved by ROV. Depths of Reykjanes Ridge corals corresponds to the mean depth of the dredge on and off bottom, and depth range is the depth interval between the dredge on and off bottom. Selection code column indicates samples included (accepted) and not included (rejected) on age distribution discussion.

Description: Uranium series dated cold-water corals from Tropic Seamount, Reykjanes Ridge, and East Equatorial Atlantic. Ages are reported in years before present (BP; where present is the year of 1950 CE) both uncorrected and corrected for initial 232Th. Some samples did not pass our quality control. Selection code column indicates samples not included on age distribution discussion: [238U] 〈2 ppm (Low U), [232Th] 〉6 ppb (High Th), [δ234Ui] 〉157‰ (High δU) and lowest quality sub-sample (duplicate).