Coupled Analytical-Numerical Model of Fish Response to Environmental Changes

Eco-physiology studies, performed in laboratory under controlled conditions, provide an essential tool for quantifying the impact of environmental changes on the metabolism and behavior of individual fish. One way of quantifying such impact is by measuring the Metabolic Scope (MS) of a fish. Laboratory experiments were performed to calculate the MS of Mugil cephalus, under different environmental conditions (temperature and oxygen). The equations derived were introduced into an ecological model, which was then coupled to a high resolution hydrodynamic model. The model was calibrated for reproducing the environmental variability in the Cabras lagoon and Gulf of Oristano (Italy). We used the model to reproduce the temporal and spatial variation in MS of a M. cephalus fish population to investigate the relationship between changes in MS and the observed seasonal migration pattern between the gulf and lagoon. Results shows that during the spring-beginning of summer period Cabras lagoon provides a higher MS M. cephalus than the Gulf of Oristano. During the rest of the year, apart from some transitional phases, the Gulf provides more suitable conditions (higher MS) for M. cephalus. Results were compared to fisheries data, showing that M. cephalus catches are highest during the end-July to August period. This period was characterized by fish were caught migrating from the lagoon into the Gulf and coincides with the reproduced drop of MS for M. cephalus in the lagoon.