The Western Mediterranean case study of the TAPAS Project has been performed by University of Murcia, Spain. The principal goal of the study is to provide data for the validation of modeling work executed in TAPAS project. In-situ measurements have included physical, chemical and biological parameters in the environment encircling fish farms. Additionally, samples of fauna and flora have been collected to investigate the nutrients retained by the encircling ecosystems, which help developing better environmental impact assessment models. The isotopic compositions are showing not only the dispersion of nutrients from fish farm effluent but also which organism or substrate kept most of the nutrients.