Constraining the ecological niche of planktonic foraminifera in the Arctic

• Main Author: Greco, Mattia
• Other Authors: Logares, Ramiro, Kucera, Michal
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2020
• Subjects: foraminifera; ecology; plankton; Arctic; 570; 570 Life sciences; biology; ddc:570; Arctic Ocean; Climate change; Foraminifera*; Global warming; Neogloboquadrina pachyderma; Planktonic foraminifera
• Online Access: https://media.suub.uni-bremen.de/handle/elib/4547; https://doi.org/10.26092/elib/344; https://nbn-resolving.org/urn:nbn:de:gbv:46-elib45479

The effects of global warming are especially pronounced in the Arctic: temperatures have increased at a rate twice as fast as in other regions of the world during the past century. This trend implies that the Arctic Ocean will likely become entirely ice-free during the summer before the end of this century. Paleoclimatic studies have shown that abrupt large-volume meltwater discharges into the Arctic Ocean and its surrounding seas, were capable of disturbing the global ocean circulation and triggering further climatic transformations. Hence, a better understanding of the past natural variability of the Arctic Ocean is needed for more accurate model predictions of future climate change. Planktonic foraminifera represent a powerful tool for palaeoceanographic reconstructions. Their fossil assemblages and the chemical composition of their calcite shells allow reconstructing the physical state of the ocean in the past. The correct interpretation of these paleo-reconstructions highly relies on a thorough understanding of species-specific ecology of living planktonic foraminifera in the water column as, for example, preferred depth habitat, calcification conditions, and biotic interactions. In the Arctic Ocean, due to the fragmented observations on this marine group, no consensus exists on the ecological preferences of the different species, hampering the correct interpretation of the paleosignal present in their shells. This thesis aims to extend the understanding of the ecology of Arctic planktonic foraminifera species by focusing on various levels of organismal biology and physiology. To constrain the environmental and biological factors controlling the vertical distribution of the species Neogloboquadrina pachyderma, a compilation of 104 vertical density profiles from the Arctic Ocean and its marginal seas was investigated using a statistical approach (Chapter 2). Contrary to what has been previously assumed, no significant relationship between N. pachyderma depth habitat and depth of chlorophyll maximum was ...