(Table 2) Planktic foraminifera and their diversity indices of sediment surface samples from the Atlantic Ocean

• Main Authors: Al-Sabouni, Nadia, Kucera, Michal, Schmidt, Daniela N
• Format: Dataset
• Language: English
• Published: PANGAEA 2007
• Subjects: 06MT41_3; 154-926A; ANT-XI/2; ARK-III/3; ARK-VII/1; Atlantic Ocean; Barcelona Coast; BC; BCR; Beella digitata; Box corer; Box corer (Reineck); Brazil Basin; Candeina nitida; Cork Harbour; Depth; bottom/max; sediment/rock; top/min; DRILL; Drilling/drill rig; Equitability; Event label; Fishers alpha index of diversity; Foraminifera; planktic; Fram Strait; GeoB1206-1; GeoB1726-1; GeoB3915-1; GeoB5142-1; Giant box corer; GIK10737-1; GIK21293-3 PS07/583; GIK21901-1 PS17/076; GKG; Globigerina bulloides; Globigerina falconensis; Globigerinella calida; Globigerinella siphonifera; Globigerinita glutinata; Globigerinita uvula; Globigerinoides conglobatus; Globigerinoides ruber pink; Globigerinoides ruber white; Globigerinoides sacculifer; Globigerinoides trilobus; Globorotalia crassaformis; Planktonic foraminifera
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.672305; https://doi.org/10.1594/PANGAEA.672305

Species distribution patterns in planktonic foraminiferal assemblages are fundamental to the understanding of the determinants of their ecology. Until now, data used to identify such distribution patterns was mainly acquired using the standard >150 µm sieve size. However, given that assemblage shell size-range in planktonic foraminifera is not constant, this data acquisition practice could introduce artefacts in the distributional data. Here, we investigated the link between assemblage shell size-range and diversity in Recent planktonic foraminifera by analysing multiple sieve-size fractions in 12 samples spanning all bioprovinces of the Atlantic Ocean. Using five diversity indices covering various aspects of community structure, we found that counts from the >63 µm fraction in polar oceans and the >125 µm elsewhere sufficiently approximate maximum diversity in all Recent assemblages. Diversity values based on counts from the >150 µm fraction significantly underestimate maximum diversity in the polar and surprisingly also in the tropical provinces. Although the new methodology changes the shape of the diversity/sea-surface temperature (SST) relationship, its strength appears unaffected. Our analysis reveals that increasing diversity in planktonic foraminiferal assemblages is coupled with a progressive addition of larger species that have distinct, offset shell-size distributions. Thus, the previously documented increase in overall assemblage shell size-range towards lower latitudes is linked to an expanding shell-size disparity between species from the same locality. This observation supports the idea that diversity and shell size-range disparity in foraminiferal assemblages are the result of niche separation. Increasing SST leads to enhanced surface water stratification and results in vertical niche separation, which permits ecological specialisation. Specific deviations from the overall diversity and shell-size disparity latitudinal pattern are seen in regions of surface-water instability, ...