Faro Lake is a coastal meromictic lagoon with singular characteristics in the Mediterranean (Messina, Sicily - Italy). It is part of the Natural Oriented Reserve of Capo Peloro (38° 15' 57″ N; 15° 37' 50″ E). In this area, traditional mollusc farming activity persists, producing 'autochthonous' mussels. This study reports of the Mytilus galloprovincialis haemolymph chemical profile and water variables determination of 1 year-lasted survey (April 2016 - March 2017). The determinations of electrolytes (Na , Cl , K , Ca , Mg , P inorganic) and heavy metals in both Faro lake water and haemolymph have been carried out. Heavy metals are elements with high density and are quite toxic in low concentrations, such as Aluminum (Al), Arsenic (As), Cobalt (Co), Chrome (Cr), Copper (Cu), Iron (Fe), Magnesium (Mg), Manganese (Mn), Lead (Pb), Tin (Sn), Zinc (Zn). Heavy metals toxicity depends, principally, on bioaccumulation processes. M. galloprovincialis is a good bio-indicator, ideal for assess levels of environmental pollution thanks to its biological, ecological and physiological characteristics. The results of this study showed a typical fluctuation range in haemolymph and water parameters, related to the water ones; chemical-physical parameters affected the ions (electrolytes and metals) levels in some period of the year. The study reports the interactions between biotic (Mytilus galloprovincialis) and abiotic (water parameters) components of Faro Lake, and creates reference data for further future study on the same area or on similar ones.