A Comparative MCDM Analysis of Potential Short-Term Measures for Dealing with Mucilage Problem in the Sea of Marmara

Mucilage is a dense and highly viscous substance made up of extracellular polysaccharides produced and secreted by the overgrowth of various aquatic species. Rising ocean temperatures, as well as human-induced stressors like inadequate treatment levels and overfishing, are common causes of such algal blooms. By mid-2020, the Sea of Marmara was covered with mucilage that threatens marine life, tourism, fisheries and the economy. Even though this was not the first mucilage outbreak in the Sea of Marmara and was not a region-specific occurrence, it was one of the worst. The phenomenon attracts increasing attention as it severely impacts the overall ecology, particularly benthic creatures. This study aims to evaluate the short-term strategies that can be used to control mucilage in the Marmara Sea according to environmental, economic, technological, technical and social criteria. It is important to note that although integrating conventional treatment plants with advanced nutrient treatment technologies is the long-term and ultimate solution to the issue; this study focuses only on short-term measures to control a mucilage outbreak in the Sea of Marmara. Fuzzy Theory is used to analyze data obtained from experts from various sectors using two separate Multi Criteria Decision Making (MCDM) models: Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The results indicate that stopping fishing is the best alternative, whereas collecting mucilage on the surface is the second-best preferable by two methods (F-TOPSIS, F-PROMETHEE). According to experts, the third option is to use beneficial bacteria to eliminate mucilage, while reactive oxygen dosing is the least appealing option