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

Gsell, Alena Sonia; Scharfenberger, Ulrike; Özkundakci, Deniz; Walters, Annika; Hansson, Lars Anders LU ; Janssen, Annette B G; Nõges, Peeter; Reid, Philip C.; Schindler, Daniel E. and Donk, Ellen Van, et al. (2016) In Proceedings of the National Academy of Sciences of the United States of America 113(50). p.8089-8095
Abstract

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... (More)

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.

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keywords
Competition, Intraguild predation, Resilience indicators, Time series, Trophic cascade
in
Proceedings of the National Academy of Sciences of the United States of America
volume
113
issue
50
pages
8089 - 8095
publisher
National Acad Sciences
external identifiers
  • scopus:85006049076
  • wos:000389696700011
ISSN
0027-8424
DOI
10.1073/pnas.1608242113
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English
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yes
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d5e95a9f-c368-402e-b6d4-f432fc32a1c7
date added to LUP
2016-12-30 07:39:57
date last changed
2017-11-05 05:11:46
@article{d5e95a9f-c368-402e-b6d4-f432fc32a1c7,
  abstract     = {<p>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.</p>},
  author       = {Gsell, Alena Sonia and Scharfenberger, Ulrike and Özkundakci, Deniz and Walters, Annika and Hansson, Lars Anders and Janssen, Annette B G and Nõges, Peeter and Reid, Philip C. and Schindler, Daniel E. and Donk, Ellen Van and Dakos, Vasilis and Adrian, Rita},
  issn         = {0027-8424},
  keyword      = {Competition,Intraguild predation,Resilience indicators,Time series,Trophic cascade},
  language     = {eng},
  month        = {12},
  number       = {50},
  pages        = {8089--8095},
  publisher    = {National Acad Sciences},
  series       = {Proceedings of the National Academy of Sciences of the United States of America},
  title        = {Evaluating early-warning indicators of critical transitions in natural aquatic ecosystems},
  url          = {http://dx.doi.org/10.1073/pnas.1608242113},
  volume       = {113},
  year         = {2016},
}