New and compiled Na/Ca measurements of the planktonic foraminifera Globigerinoides ruber. The dataset contains data from foraminiferal samples 1) collected from plankton tows and sediment traps which span a wide salinity range (32.5 - 40.7 salinity units) across the Bay-of-Bengal, Arabian Sea, and Red Sea, 2) cultured in the laboratory under varying carbonate chemistry, and 3) a globally-distributed suite of core-top samples. Na/Ca was measured using both solution and laser ablation ICP-MS. The foraminiferal Na/Ca data are provided alongside environmental parameters for each sample (e.g. temperature, salinity, pH, bottom water Omega calcite), in order to assess the environmental controls on Na/Ca in foraminifera. The data accompany the following manuscript: Gray et al. (2023, doi:10.1016/j.gca.2023.03.011).
LA-ICP-MS data from three different experiments including five foraminiferal species: Ammonia confertitesta (Bourgenuf, France), Bulimina marginata, Cassidulina laevigata (Gullmard Fjord, Sweden), Amphistegina lessonii and Operculina ammonoides (Eilat, Israel). Foraminifera were cultured at different oxygen concentrations (30% and 100% oxygen saturation). Element to calcium ratio (E/Ca) and partition coefficients (D) of Mg, Mn and Sr are noted for individual laser ablation measurements per specimen.
Metabarcoding has become the workhorse of community ecology. Sequencing a taxonomically informative DNA fragment from environmental samples gives fast access to community composition across taxonomic groups, but it relies on the assumption that the number of sequences for each taxon correlates with its abundance in the sampled community. However, gene copy number varies among and within taxa, and the extent of this variability must therefore be considered when interpreting community composition data derived from environmental sequencing. Here we measured with single-cell qPCR the SSU rDNA gene copy number of 139 specimens of five species of planktonic foraminifera. We found that the average gene copy number varied between of ~4 000 to ~50 000 gene copies between species, and individuals of the same species can carry between ~300 to more than 350 000 gene copies. This variability cannot be explained by differences in cell size and considering all plausible sources of bias, we conclude that this variability likely reflects dynamic genomic processes acting during the life cycle. We used the observed variability to model its impact on metabarcoding and found that the application of a correcting factor at species level may correct the derived relative abundances, provided sufficiently large populations have been sampled.
Deoxygenation affects many continental shelf seas across the world today and results in increasing areas of hypoxia (dissolved oxygen concentration ([O2]) <1.4 ml/L). The Baltic Sea is increasingly affected by deoxygenation. Deoxygenation correlates with other environmental variables such as changing water temperature and salinity and is directly linked to ongoing global climate change. To place the ongoing environmental changes into a larger context and to further understand the complex Baltic Sea history and its impact on North Atlantic climate, we investigated a high accumulation‐rate brackish‐marine sediment core from the Little Belt (Site M0059), Danish Straits, NW Europe, retrieved during the Integrated Ocean Drilling Program (IODP) Expedition 347. We combined benthic foraminiferal geochemistry, faunal assemblages, and pore water stable isotopes to reconstruct seawater conditions (e.g., oxygenation, temperature, and salinity) over the past 7.7 thousand years (ka). Bottom water salinity in the Little Belt reconstructed from modeled pore water oxygen isotope data increased between 7.7 and 7.5 ka BP as a consequence of the transition from freshwater to brackish‐marine conditions. Salinity decreased gradually (from 30 to 24) from 4.1 to ~2.5 ka BP. By using the trace elemental composition (Mg/Ca, Mn/Ca, and Ba/Ca) and stable carbon and oxygen isotopes of foraminiferal species Elphidium selseyensis and E. clavatum, we identified that generally warming and hypoxia occurred between about 7.5 and 3.3 ka BP, approximately coinciding in time with the Holocene Thermal Maximum (HTM). These changes of bottom water conditions were coupled to the North Atlantic Oscillation (NAO) and relative sea level change.
The dataset includes foraminiferal geochemistry and assemblage data, and pore water oxygen isotopes. The samples were collected during IODP Expedition 347 from Site M0059, located in the southern section of the Little Belt in the Baltic Sea. We have measured trace element concentrations (by LA-ICP-MS), oxygen and carbon isotopes of foraminiferal calcite, and fauna assemblage, for reconstruction of past environmental conditions over the past ~7.5 thousand years. We have also measured pore water oxygen isotopes from the same site. In the dataset we also present the trace element concentrations of foraminiferal calcite from IODP347 Site M0059 measured by solution-based ICP-OES. In addition, we include the measurement of water column salinity and oxygen isotopes data from cruise MSM 50 between the Skagerrak and the southern Baltic Sea.