Coastal ecosystems are subjected to multiple stresses, from physical disturbance to chemical contamination related to the local anthropogenic activities. The recent European directives and Italian laws recommend that the assessment of the ecological quality of costal seawater should be based on an integrated approach, taking into account the ecological complexity of the systems and highlighting the potential sources of impact. Here, we present the results of an environmental study carried out in the marine coastal area affected by the sea discharge of a Combined Cycle Power Plant (Torre Cavallo, Brindisi) and characterized by the presence of a Posidonia oceanica meadow. The study focused on the concentration of chemical contaminants in sediments, coupled with the study of quali-quantitative determinations of biological benthic communities meio- and macrozoobenthos). Data were integrated with data of phenology and lepidochronology of P. oceanica, as well as the concentrations of trace elements in leaves and rhizomes, in order to identify potential sources of stress. Results suggested a good status of health of the coastal marine ecosystem.