The Regional Natural Reserve of the Isonzo River Mouth is an Italian coastal area, where biodiversity reaches high levels. Four sampling sites were chosen and seasonal samplings were conducted (autumn 2009 and spring 2010) using a non invasive sampling strategy (leaf bag technique) for studying both detritus processing and colonization by macrobenthic invertebrates. The main chemical and physical water parameters were monitored in water column. Intra - and inter - seasonal differences of the total number, taxa composition, and the vegetable organic matter decomposition rates were investigated. Diptera Chironomidae was the dominant taxon in both seasons, followed by Crustacea. Significant differences were foundfor used community descriptors (total number, number of taxa). Decomposition rates showed dignificant seasonal differences.
