The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Helena Filipsson, foto Erik Thor

Helena Filipsson

Professor

Helena Filipsson, foto Erik Thor

Assessing proxy signatures of temperature, salinity, and hypoxia in the Baltic Sea through foraminifera-based geochemistry and faunal assemblages

Author

  • Jeroen Groeneveld
  • Helena L. Filipsson
  • William E.N. Austin
  • Kate Darling
  • David McCarthy
  • Nadine B.Quintana Krupinski
  • Clare Bird
  • Magali Schweizer

Summary, in English

Current climate and environmental changes strongly affect shallow marine and coastal areas like the Baltic Sea. This has created a need for a context to understand the severity and potential outcomes of such changes. The context can be derived from paleoenvironmental records during periods when comparable events happened in the past. In this study, we explore how varying bottom water conditions across a large hydrographic gradient in the Baltic Sea affect benthic foraminiferal faunal assemblages and the geochemical composition of their calcite tests. We have conducted both morphological and molecular analyses of the faunas and we evaluate how the chemical signatures of the bottom waters are recorded in the tests of several species of benthic foraminifera. We focus on two locations, one in the Kattegat (western Baltic Sea) and one in Hanö Bay (southern Baltic Sea). We show that seawater Mn-•Ca, Mg-•Ca, and Ba-•Ca (Mn-•Casw, Mg-•Casw, and Ba-•Casw) variations are mainly controlled by dissolved oxygen concentration and salinity. Their respective imprints on the foraminiferal calcite demonstrate the potential of Mn-•Ca as a proxy for hypoxic conditions, and Ba-•Ca as a proxy for salinity in enclosed basins such as the Baltic Sea. The traditional use of Mg-•Ca as a proxy to reconstruct past seawater temperatures is not recommended in the region, as it may be overprinted by the large variations in salinity (specifically on Bulimina marginata), Mg-•Casw, and possibly also the carbonate system. Salinity is the main factor controlling the faunal assemblages: a much more diverse fauna occurs in the higher-salinity (- 32) Kattegat than in the low-salinity (- 15) Hanö Bay. Molecular identification shows that only Elphidium clavatum occurs at both locations, but other genetic types of both genera Elphidium and Ammonia are restricted to either low- or high-salinity locations. The combination of foraminiferal geochemistry and environmental parameters demonstrates that in a highly variable setting like the Baltic Sea, it is possible to separate different environmental impacts on the foraminiferal assemblages and therefore use Mn-•Ca, Mg-•Ca, and Ba-•Ca to reconstruct how specific conditions may have varied in the past.

Department/s

  • Quaternary Sciences
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publishing year

2018-09-07

Language

English

Pages

403-429

Publication/Series

Journal of Micropalaeontology

Volume

37

Issue

2

Document type

Journal article

Publisher

Geological Society of London

Topic

  • Geology

Status

Published

Project

  • Fält och experimentell kalibrering av marina temperaturindikatorer genom användning av bentiska foraminiferer

ISBN/ISSN/Other

  • ISSN: 0262-821X