Stochastic dynamics of Cyanobacteria in long‐term high‐frequency observations of a eutrophic lake

Stephen R. Carpenter,Babak M. S. Arani,Egbert Van Nes,Marten Scheffer,Paul C. Hanson,Emily H. Stanley

doi:10.1002/lol2.10152

Abstract

AbstractConcentrations of phycocyanin, a pigment of Cyanobacteria, were measured at 1‐min intervals during the ice‐free seasons of 2008–2018 by automated sensors suspended from a buoy at a central station in Lake Mendota, Wisconsin, U.S.A. In each year, stochastic‐dynamic models fitted to time series of log‐transformed phycocyanin concentration revealed two alternative stable states and random factors that were much larger than the difference between the alternate stable states. Transitions between low and high states were abrupt and apparently driven by stochasticity. Variation in annual magnitudes of the alternate states and the stochastic factors were not correlated with annual phosphorus input to the lake. At daily time scales, however, phycocyanin concentration was correlated with phosphorus input, precipitation, and wind velocity for time lags of 1–15 d. Multiple years of high‐frequency data were needed to discern these patterns in the noise‐dominated dynamics of Cyanobacteria.

Highlights

Concentrations of phycocyanin, a pigment of Cyanobacteria, were measured at 1-min intervals during the icefree seasons of 2008–2018 by automated sensors suspended from a buoy at a central station in Lake Mendota, Wisconsin, U.S.A
Phycocyanin dynamics in Lake Mendota were dominated by stochasticity
Analyses of a longer time series (21 yr) of phosphorus loading and manual counts of Cyanobacteria quantified the relationship of phosphorus inputs to Cyanobacteria mean biomass and bloom frequency (Stow et al 1997; Lathrop et al 1998)

Summary

Introduction

Concentrations of phycocyanin, a pigment of Cyanobacteria, were measured at 1-min intervals during the icefree seasons of 2008–2018 by automated sensors suspended from a buoy at a central station in Lake Mendota, Wisconsin, U.S.A. To compare the roles of equilibria vs environmental variability for Cyanobacteria dynamics in surface waters, we studied fluctuations of phycocyanin, a characteristic pigment of Cyanobacteria, at 1-min intervals using sensors suspended from a centrally located buoy during the ice-free seasons of 11 yr in eutrophic Lake Mendota, Wisconsin. The time series were analyzed using drift-diffusion-jump models (Carpenter and Brock 2011) (Supporting Information).

Results

Conclusion