title: Reversal of a cyanobacterial bloom in response to early warnings.
abstract: Directional change in environmental drivers sometimes triggers regime shifts in ecosystems. Theory and experiments suggest that regime shifts can be detected in advance, and perhaps averted, by monitoring resilience indicators such as variance and autocorrelation of key ecosystem variables. However, it is uncertain whether management action prompted by a change in resilience indicators can prevent an impending regime shift. We caused a cyanobacterial bloom by gradually enriching an experimental lake while monitoring an unenriched reference lake and a continuously enriched reference lake. When resilience indicators exceeded preset boundaries, nutrient enrichment was stopped in the experimental lake. Concentrations of algal pigments, dissolved oxygen saturation, and pH rapidly declined following cessation of nutrient enrichment and became similar to the unenriched lake, whereas a large bloom occurred in the continuously enriched lake. This outcome suggests that resilience indicators may be useful in management to prevent unwanted regime shifts, at least in some situations. Nonetheless, a safer approach to ecosystem management would build and maintain the resilience of desirable ecosystem conditions, for example, by preventing excessive nutrient input to lakes and reservoirs.
authors.affiliation: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22901; srcarpen@wisc.edu pacem@virginia.edu.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Pace
authors.affiliation: Department of Ecology, Evolution, and Natural Resources, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901.
authors.forename: Ryan D
authors.identifier: 0000-0002-7267-5395
authors.initials: RD
authors.lastname: Batt
authors.affiliation: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22901.
authors.forename: Cal D
authors.initials: CD
authors.lastname: Buelo
authors.affiliation: Center for Limnology, University of Wisconsin, Madison, WI 53706; srcarpen@wisc.edu pacem@virginia.edu.
authors.forename: Stephen R
authors.identifier: 0000-0001-8097-8700
authors.initials: SR
authors.lastname: Carpenter
authors.affiliation: Cary Institute of Ecosystem Studies, Millbrook, NY 12545.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Cole
authors.affiliation: Center for Limnology, University of Wisconsin, Madison, WI 53706.
authors.forename: Jason T
authors.initials: JT
authors.lastname: Kurtzweil
authors.affiliation: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22901.
authors.forename: Grace M
authors.initials: GM
authors.lastname: Wilkinson
mesh_terms: D000458:Cyanobacteria / Q000502:physiology*; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D005068:Eutrophication / Q000502:physiology*; D060106:Lakes / Q000382:microbiology; D008954:Models, Biological
keywords: bloom; early warning; eutrophication; lake; resilience indicator