Monitoring Biological Rhythms Through the Dynamic Model Identification of an Oyster Population

The measurements of valve activity in a population of bivalves under natural environmental conditions (16 oysters in the Bay of Arcachon, France) are used for a physiological model identification. A nonlinear autoregressive exogenous (NARX) model is designed and tested. The method to design the model has two parts: 1) structure of the model: the model takes into account the influence of environmental conditions using the measurements of sunlight intensity, the moonlight, tide levels, precipitation, and water salinity levels. A possible influence of the internal circadian/circatidal clocks is also analyzed and 2) least square calculation of the model parameters. Through this paper, it is demonstrated that the developed dynamical model of the oyster valve movement can be used for estimating normal physiological rhythms of permanently immersed oysters and can be considered for detecting perturbations of these rhythms due to changes in the water quality, i.e., for ecological monitoring.