Noise and Nonlinearity in an Ecological System

In this chapter, a case study from marine ecology is presented in which the application of techniques from nonlinear time series analysis is shown to provide insight into the interplay between stochastic physical forcing and nonlinear biological response in a natural system. Specifically, the replenishment of a population of reef fishes is analyzed in detail, and important nonlinearities are demonstrated in the processes underlying variability in the supply of larval propagules to the reef. This information is used to guide the construction of a series of models which attempt to forecast larval supply from readily measured physical variables. The most successful models are those that account for the nonlinearities in the response of larvae to their physical environment. Such models provide better forecasts than can be achieved with conventional linear techniques and identify processes hidden to linear analysis. The importance of understanding the interplay between noise and nonlinearity in ecological systems is discussed.