Simplifying a lake to 10,000 data points: Using spatial analysis to detect an impending regime shift

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Small perturbations are capable of causing ecosystems to undergo catastrophic transitions from one stable state to another with greatly altered ecosystem functions and services.  Due to the increased difficulty in restoring ecosystems after undergoing a catastrophic transition, it would be useful to detect whether a system is close to a transition, with the hopes of avoiding one altogether.  It has been suggested that ecosystems will display a unique set characteristics, often referred to as early warning indicators, prior to undergoing these catastrophic transitions.  Ecologists have proposed multiple spatial and temporal analysis techniques to detect these early warning indicators.  However, testing is still in the infant stages, particularly for spatial-based indicators, due to the difficulty in collecting high resolution spatial data.  Using the FLAMe system (a novel boat-mounted flow-through sensor platform) we were able to collect unprecedentedly high spatial resolution (<3m) of lake chemistry and biological indicators.  We experimentally induced a transition from a phytoplankton- to cyanobacteria-dominated ecosystem in a set of experimental lakes, and will be using a suite of spatial analysis to test the ability of high-frequency spatial sampling in detecting early warning indicators.  Preliminary analyses show that these small (<3 ha.) lakes display substantial spatial heterogeneity in surface water chemistry and photosynthetic activity (chlorophyll-a and blue-green algae) that will offer insight into the usefulness of spatial analysis in detecting an impending catastrophic transition in aquatic systems.