Global assessment of species-specific habitats of planktonic foraminifera : an ecosystem modeling approach

• Main Author: Kretschmer, Kerstin
• Other Authors: Schulz, Michael, Wefer, Gerold
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2017
• Subjects: planktonic foraminifera; zooplankton; ecosystem modeling; climate change; 550; 550 Earth sciences and geology; ddc:550; Neogloboquadrina pachyderma; North Atlantic; Planktonic foraminifera; Sea ice
• Online Access: https://media.suub.uni-bremen.de/handle/elib/1367; https://nbn-resolving.org/urn:nbn:de:gbv:46-00106366-16

Over the last few million years, the Eartha s climate system has changed continuously on decadal to millennial time scales. Past climate conditions have been reconstructed based on fossil evidence of marine microorganisms, such as planktonic foraminifera. Planktonic foraminifera exhibit species-specific seasonal production patterns and different preferred depth habitats. To precisely reconstruct past climate conditions these spatial and temporal variations within the individual species distribution have to be considered. In this regard, an ecosystem modeling approach can help to gain a better knowledge about species-specific habitat shifts under climate change. In this study, a planktonic foraminifera model is used to predict monthly concentrations of the colder-water species Neogloboquadrina pachyderma, Neogloboquadrina incompta, and Globigerina bulloides, and of the warm-water species Globigerinoides ruber (white) and Trilobatus sacculifer throughout the world ocean. In particular, the seasonal distribution of the polar species N. pachyderma in the surface mixed layer of the North Atlantic Ocean during the last glacial period was investigated. In response to changes in the sea ice cover and food supply, the peak timing of N. pachyderma is shifted from the last glacial period to modern conditions by several months. However, for a more realistic simulation of species-specific habitats, the planktonic foraminifera model PLAFOM was adapted to allow for resolving the vertical dimension. This new model version estimates the foraminiferal biomass of the colder- and warm-water species as a function of temperature, nutrition, competition, and in particular light. To predict the species concentration over different water depths the model code of the improved version of the planktonic foraminifera model was added to the code trunk of the ocean component of a global earth system model. This model produces seasonally and vertically coherent distribution patterns that are in good agreement with available observations ...