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Dan Hammarlund

Dan Hammarlund

Professor

Dan Hammarlund

Combining limnology and palaeolimnology to investigate recent regime shifts in a shallow, eutrophic lake

Author

  • Linda Randsalu Wendrup
  • Daniel Conley
  • Jacob Carstensen
  • Lars-Anders Hansson
  • Christer Brönmark
  • Sherilyn C. Fritz
  • Preetam Choudhary
  • Joyanto Routh
  • Dan Hammarlund

Summary, in English

In this study, we demonstrate that an integrated approach, combining palaeolimnological records and limnological monitoring data, can increase our understanding of changing ecological patterns and processes in shallow lakes. We focused on recent regime shifts in shallow Lake Krankesjon, southern Sweden, including the collapse of the clear-water state in 1975 and its subsequent recovery in the late 1980s. We used diatom, hydrocarbon and biogenic silica sediment records, in concert with limnological data sets on nutrient concentrations, water clarity, chlorophyll-a and water depth, to investigate the shifts. The shift from clear to turbid conditions was abrupt and occurred over 1 to 2 years, whereas recovery of the clear-water state was more gradual, taking 4-5 years. In 1978, shortly after the first regime shift in water clarity, the diatom community underwent a significant shift. It became less diverse, with decreased abundance of epiphytic and planktonic taxa. Despite rising phosphorus concentrations and lower abundance of submerged macrophytes, Lake Krankesjon has remained in the clear-water state over the past 20 years, although this state seems to be increasingly unstable and susceptible to collapse. The complex reactions of the entire lake ecosystem to major changes in lake-water clarity, as shown by the palaeolimnological variables investigated in this study, emphasize the importance of careful lake and catchment management if a stable, clear-water state is desired.

Department/s

  • Quaternary Sciences
  • Division aquatic ecology
  • MERGE: ModElling the Regional and Global Earth system
  • BECC: Biodiversity and Ecosystem services in a Changing Climate
  • Aquatic Ecology

Publishing year

2014

Language

English

Pages

437-448

Publication/Series

Journal of Paleolimnology

Volume

51

Issue

3

Document type

Journal article

Publisher

Springer

Topic

  • Ecology
  • Geology

Keywords

  • Regime shift
  • Monitoring
  • Ecosystem
  • Alternative stable state
  • Diatoms
  • Hydrocarbons

Status

Published

Research group

  • Aquatic Ecology

ISBN/ISSN/Other

  • ISSN: 0921-2728