Resumen de Floating plastic debris in the central and western mediterranean sea: current status and its social perception
Plastics are currently one of the most widely distributed litter in marine ecosystems worldwide. The floating fraction of these debris are estimated to represent about 1% of the plastics that enter into the marine environment where subtropical ocean gyres are considered to be the main convergence zones of floating plastics. The dense social system around the Mediterranean Sea pressures this environment being aggravated due to its semi-enclosed condition. Concern about plastic waste has been increasing in recent years due to the adverse effects it can cause on the Mediterranean ecological systems, its persistence in the environment and the consequences for social systems.
The problem of plastic pollution has a profound social origin. In this context, this work is aimed to assess the current state of the problem of floating plastic debris in the Central and Western Mediterranean in both environmental and social systems. From the ecological point of view, the surface of the Mediterranean was sampled on three different spatial scales; a regional macro scale in the Northwestern-Central Med. Sea, a regional micro scale in the Balearic Islands (Spain) and a local scale focused on the current MPA of the Menorca Channel (Balearic Islands). In addition, a pilot seasonal study was carried out in the local scale. The distribution and concentrations observed along the sea surface confirmed the omnipresence and persistence of plastic waste in marine ecosystems, resulting in maximum concentrations of particles off the NW coast of Ibiza Island (Spain) and concentration by weight near to the Gulf of Taranto (Italy). The results of the 139 samples analyzed in total confirm the significant superiority of microplastics on the colbded waste observed in the Mediterranean surface. In general, the concentration of plastic waste was higher in the areas near the coast, with concentrations significantly higher in the Balearic Islands than in the rest of the Mediterranean. However, the seasonal distribution of plastic concentrations seems to be influenced by multiple factors in which particles appear to be directed by oceanographic variables, while the weight by social variables.
From a social point of view, the perception and awareness of three key stakeholders in the decision-making processes (experts, public administrators and business agents) and beach users on the island of Mallorca were assessed. Perceptions of the plastic issue were explored by applying a mixed methodology in three focus groups formed by Mallorcan stakeholders. The participants' broad view of plastic problems was demonstrated, in which topics covering most of the material's life cycle were developed. The main problems detected were centered within the social systems, where the excess of plastic used in the production and consumption processes was considered the main problem of plastic by the three groups. However, its approach to the definition of the problem was limited to the areas in which stakeholders were defined. Through a questionnaire distributed on the beaches, the perception and awareness of its users was analyzed. The result showed that users perceived plastics as an important environmental problem whose main causes are plastic excess and lack of public awareness, as well as, present a rejection attitude to the waste found on the beaches that influences the user's selection.
The results presented in this doctoral thesis contribute to the development and application of knowledge of the state of plastic pollution in the Mediterranean Sea in the context of social-ecological systems.
