Assessment of marine litter barrier initiatives and their potential as a prevention strategy in Brazil

Abstract Considering that most solid waste reaching the ocean originates from activities on land and flows and flushes through rivers and estuaries to the sea, downstream strategies to intercept marine litter input, such as traps, booms, and boats, have grown in popularity over the past years. However, with the growing interest from the public and private sectors to expand and finance the interception of marine litter, it is essential to assess the existing initiatives, their operational capacity, and challenges. Thus, the present study sought to take an initial step toward this goal by identifying and mapping current marine litter interception initiatives in Brazil, often referred to as ecobarriers and ecoboats, characterizing them according to their level of maturity, type of ecosystem in which they operate, the structures used, how long the operation has been in place, which partnerships enable the operation, the indicators to measure effectiveness, general financial cost, and current demands for the operation to continue/to be implemented, comparing their occurrences with hotspots of marine litter input reported in the literature. A two-phase online survey contacted over 200 stakeholders who could provide information on the issue. A total of 19 boom and boat initiatives were identified, of which 11 could be accurately mapped, most concentrated in the Brazilian Southeast and at an initial phase of their operation (e.g., planned/being planned or raising funds but not fully implemented). All initiatives reported a demand for resources to implement/continue their operations. A mismatch was observed between the location of the initiatives mapped and the occurrence of marine litter hotspots, although these gaps should be interpreted with caution, considering plastic leakage estimates and sub-representation of initiatives. Finally, we highlight several aspects that should be considered before designing and implementing litter booms and other interception strategies.