RESOURCE AND ENERGY RECOVERY FROM SEAGRASS: A LIFE CYCLE-ASSESSMENT APPROACH

Seagrass meadows are important habitats that provide significant ecosystem services to our planet (Unsworth et al., 2019). Global seagrass distribution was estimated to be in the range of 177,000-600,000 km2 (McKenzie et al., 2020), so seagrass management can be considered an issue at worldwide level. The effects of seagrass wrack lying onshore include the hindering of tourism in the affected areas (Corraini et al., 2018), as well as the contribution to greenhouse gas (GHG) emissions (Liu et al., 2019). On the other hand, seagrass wrack is an important component of coastal environments, bringing ecological benefits (Vacchi et al., 2017), such as providing food and habitat to local fauna and supplying nutrients for vegetation. In many administrative districts of touristic interest, it is common to remove the material from the beach, although this practice is often associated with the use of heavy machinery (Simeone et al., 2013), a significant shoreline regression and a strong impact on the beach morphology (Boudouresque et al., 2016). For sustainable management, a paradigm shift should be made, considering seagrass wrack no longer as a waste, but as a resource. However, in seagrass management different aspects have to be considered, including ecological benefits provided by the biomass left onshore, the social and economic interests behind seagrass removal, the local availability of plants for seagrass energy and resource recovery, the macro- and micro-pollutants presence in the collected material, the environmental emissions throughout the entire life cycle. In this study, three alternative seagrass wrack management scenarios to current landfill conferral (anaerobic digestion-AD, composting, ecological restoration) were considered for the coastline of Grado Municipality (Northeast of Italy), evaluating their different impacts from an environmental and economic perspective using life cycle assessment (LCA) and life cycle costing (LCC) approaches. The investigated area overlooked the Adriatic Sea (Friuli Venezia Giulia). A beach length of about 1.6 km was considered in the analysis. The sampling campaign lasted from winter 2015 to summer 2018, and was differentiated according to the collection season due to different seagrass management. The collected seagrass included different species (Cymodocea nodosa, Zostera marina, Nanozostera noltii).