RajReni B. Kaul (1), and John M. Drake (1)
(1) Odum School of Ecology, University of Georgia
Incorporating environmental noise into stochastic population models lead to two general observations. On one hand, minor environmental noise in the model simply increases fluctuation of the population’s size around the stable upper bound equilibrium. On the other hand, when environmental noise is significantly large the population is not simply pushed to a different equilibrium at extinction but the upper bound equilibrium disappears and an equilibrium at extinction appears. Under large environmental noise extinction is the only stable equilibrium. This is a type of noise-induced phase transition (NIPT). As long as the noise persists interventions to maintain the population will not have any lasting impact. Looking forward, the IPCC predicts climate change will also bring increased environmental variation. Given the stochastic model predictions, this increase in environmental noise as opposed to the shift in mean environment has the potential to be more detrimental to population survival. However, the possibility or prevalence of NIPT in biological systems is unknown. The proposed work will explore the possibility of NIPT in a biological system using a microcosm approach. Chemostats of the cyanobacteria Aphanizomenon will be grown under light regimes with varying levels of noise. A model of this system predicts a NIPT when the environmental noise is greater than one-third of the ideal environment (μ = 600PAR, 2 = 280PAR).