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Ports are affected by a high rate of sedimentation that requires frequent dredging of the seabed to restore bathymetric levels. In some cases, the sediments consist of a large amount of leaves of phanerogams (e.g., P. oceanica) that must be treated differently from what is required by the Italian law on sediments (Ministerial Decree No. 173/2016), since soils cannot be treated either as sediment or as waste. About one meter of the sediment cores collected in the Port of Sperlonga consisted of organic waste derived from a different stage of seagrass decomposition. To optimize the management, the decomposed organic detritus was characterized from physical-chemical (content of nutrient and pollutants), ecotoxicological and mechanical (microtensile, microscopic structure) points of view, to define different management solutions for the final disposal. The results of this study describe the characteristics of this type of organic detritus, highly present in Mediterranean coastal ecosystems, and allow a better definition of different possible solutions to valorize this resource instead of disposing it in an organic waste landfill. The search for environmentally friendly options for waste management is of particular interest in terms of the green economy, and the reduction of CO2 emissions as an indirect effect obtained by improving waste recycling.

This paper presents the results of seasonal and depth distribution of epiphytic flora and vegetation on Mediterranean seagrass Posidonia oceanica (L.) Delile leaves. The investigations were carried out seasonally, in 1984 at 5, 15 and 25m depth in one Posidonia bed on the west coast of Hvar Island (middle Adriatic). A total of 103 epiphytic algal taxa were determined (Rhodophyta 72 taxa, Phaeophyta 16 taxa and Chlorophyta 15 taxa). The highest number of taxa was observed during winter (75 taxa) and at 5m depth (78 taxa), and the lowest during autumn (63 taxa) and at 15m depth (73 taxa). The S&Oslash ; ; RRENSEN&#8217 ; ; s coefficient of similarity, R/P quotient and Cluster Analysis were calulated for similarity epiphytic floras of different Mediterranean and Adriatic areas. In epiphytic vegetation the mean total covering of sample (Rt%) decreased along the depth gradient (21.56% at 5m and 11.03% at 25m). Within qualitative dominance (DN%) predominated the filamentous algal taxa of Phsl and Ssl ecological supergroups, and D ecological group. Regarding quantitative dominance (DR%), in this vegetation dominated the calcareous, filamentous and foliose algal taxa of Phsl and Ssl ecological supergroups, and HP and D ecological groups. The Cluster Analysis show that a high significant (about 87%) of epiphytic vegetations exist between the investigated vegetation (present paper) and group of areas which are formed of Sicily, Dubrovnik, Ischia and French coast. Within the structure of epiphytic vegetation it is possible to separate the algal taxa for which the high values of RMi% &#61619 ; ; 0.50% along with high values of P (3, 4 or 5) were recorded, that the most significantly participated in structure of this vegetation. At all depths there were present the following: Chondria tenuissima, Dictyota linearis, Pneophyllum fragile and Fosliella fainosa var. farinosa, and at different depths there were also found: Spyridia filamentosa, Herposiphonia secunda f. tenella, Laurencia obtusa, Ceramium nodosum and Myrionema orbiculare at 5m depth ; Polysiphonia fruticulosum, Spyridia filamentosa, Herposiphonia secunda f. tenella, Laurencia obtusa and Polysiphonia sp.3 at 15m depth ; Antithamnion cruciatum var. profundum and Polysiphonia sp.3 at 25m depth.