Nonlinear time series analysis of ecological data collected in the Lagoon of Orbetello, Italy

In this paper a nonlinear analysis of time series representing dissolved oxygen, temperature, pH and salinity data, collected in the Lagoon of Orbetello (Grosseto, Italy) is performed. A first biological inspection of the data shows that the coastal area is highly eutrophic and subject to unexpected phenomena, like anoxic and distrofic crises. From a more theoretical point of view, the ecological complexity of this ecosystem suggests the need to consider nonlinear models for understanding the dynamics of the system. The appearance of low dimensional deterministic chaos is demonstrated, using the nonlinear time series analysis approach by means of attractor reconstruction and the computation of the Maximum Lyapunov Exponent.