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Evaluating early-warning indicators of critical transitions in natural aquatic ecosystems

  • Alena Sonia Gsell
  • Ulrike Scharfenberger
  • Deniz Özkundakci
  • Annika Walters
  • Lars Anders Hansson
  • Annette B G Janssen
  • Peeter Nõges
  • Philip C. Reid
  • Daniel E. Schindler
  • Ellen Van Donk
  • Vasilis Dakos
  • Rita Adrian
Publishing year: 2016-12-13
Language: English
Pages: 8089-8095
Publication/Series: Proceedings of the National Academy of Sciences of the United States of America
Volume: 113
Issue: 50
Document type: Journal article
Publisher: National Acad Sciences

Abstract english

Ecosystems can show sudden and persistent changes in state despite only incremental changes in drivers. Such critical transitions are difficult to predict, because the state of the system often shows little change before the transition. Early-warning indicators (EWIs) are hypothesized to signal the loss of system resilience and have been shown to precede critical transitions in theoretical models, paleo-climate time series, and in laboratory as well as whole lake experiments. The generalizability of EWIs for detecting critical transitions in empirical time series of natural aquatic ecosystems remains largely untested, however. Here we assessed four commonly used EWIs on long-term datasets of five freshwater ecosystems that have experienced sudden, persistent transitions and for which the relevant ecological mechanisms and drivers are well understood. These case studies were categorized by three mechanisms that can generate critical transitions between alternative states: competition, trophic cascade, and intraguild predation. Although EWIs could be detected in most of the case studies, agreement among the four indicators was low. In some cases, EWIs were detected considerably ahead of the transition. Nonetheless, our results show that at present, EWIs do not provide reliable and consistent signals of impending critical transitions despite using some of the best routinely monitored freshwater ecosystems. Our analysis strongly suggests that a priori knowledge of the underlying mechanisms driving ecosystem transitions is necessary to identify relevant state variables for successfully monitoring EWIs.


  • Ecology
  • Competition
  • Intraguild predation
  • Resilience indicators
  • Time series
  • Trophic cascade


  • ISSN: 0027-8424
Lars-Anders Hansson
E-mail: lars-anders [dot] hansson [at] biol [dot] lu [dot] se


Aquatic ecology

+46 46 222 41 69






Research group

Aquatic Ecology

Other projects I´m involved in

Doctoral students and postdocs

PhD students, main supervisor

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