Arctic planktonic foraminifera pelagic carbonate production and sedimentation under changing environmental conditions

Abstract

The Arctic Ocean is substantially affected by ongoing warming and sea ice loss. Climatic change further influences biological processes. Altogether, this can result in a modification of the marine carbon cycle, alike important for the climate and the ecosystem of the Arctic Ocean and beyond. In order to unravel the effects of changes in the Arctic Ocean on planktonic foraminifera, one group of marine organisms producing and storing carbon, this thesis presents studies on planktonic foraminifera from all over the Arctic and Subarctic Ocean, working with samples from both within the water column and from the sediments. The produced calcite mass is determined by comprehensive measurements of shell size and weight of all in the Arctic and Subarctic Ocean abundant species of planktonic foraminifera. Measurements on shell weights on samples from plankton nets, sediment traps and sediment cores from a total of 13 locations are used to further calculate foraminifera calcite mass fluxes in the water column and foraminifera calcite mass accumulation in the sediments using published data from all over the Arctic and Subarctic Ocean. Overall, this thesis provides new details on the calcite mass production of planktonic foraminifera in the Arctic and Subarctic Ocean. It is shown that they are a relevant contributor to fluxes of CaCO3 from the pelagic zone towards the sediments. This makes planktonic foraminifera an important component of the marine carbon cycle, which needs to be further constrained to understand how ongoing climate change will influence their contribution to drawdown of carbon.