Modeling the Spatial and TemporalDistribution of PlanktonicForaminifera

• Main Author: Fraile Ugalde, Igaratza
• Other Authors: Kucera, Michal, Schulz Michael
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2008
• Subjects: planktonic foraminifera; seasonality; reconstructions; LGM; sensitivity; model; 550; 550 Earth sciences and geology; ddc:550; Neogloboquadrina pachyderma; North Atlantic; Planktonic foraminifera
• Online Access: https://media.suub.uni-bremen.de/handle/elib/2551; https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000111552

Planktonic foraminifera contribute substantially to the fossil record of marine sediments,and due to their excellent preservation in sediments, the fossil shells areof great paleoceanographic significance. Temporal variations in sedimentary faunalassemblages and geochemical composition of the individual fossil shells havebecome important proxies for past oceanic conditions. Different ecological preferencesbetween species cause distinct seasonal patterns, and the imprint of differingseasonal production is preserved in the sedimentary record. Accurate knowledge offoraminiferal ecology and seasonal succession is indeed crucial to correctly interpretcorresponding proxy-based reconstructions. Planktonic foraminifera are known tobe sensitive to temperature, and therefore climate changes may alter the seasonalpattern of species. Any change in the timing of the largest flux to the seafloor thatmay have occurred in the past will lead to a bias in estimated paleotemperature.Therefore, this dissertation focuses on the variability of planktonic foraminiferalseasonality through time, and discusses its implications for paleotemperature reconstructions.A numerical model simulating the population dynamics of planktonic foraminiferawas developed and coupled to an existing marine ecosystem model. This modelis forced with a global hydrographic dataset (e.g., temperature, mixed layer depth)and with biological information taken fromthe ecosystem model to predict monthlyconcentration of the following foraminifera species: Neogloboquadrina pachyderma(dextral and sinistral varieties), Globigerina bulloides, Globigerinoides ruber (white variety)and Globigerinoides sacculifer. These species are sensitive to sea-surface temperature,and due to their high spatial coverage and abundance are the most commonplanktonic foraminifera species used in paleoceanography. The model results forthe global distribution of planktonic foraminifera for modern conditions are comparedto available core-top and sediment-trap data. In the North Atlantic, ...