Analysis, Animals, Biobío region, Chile, Ecosystem, Environmental Monitoring - methods, Fish species, Fishes - metabolism, FTIR, Gastrointestinal Contents - chemistry, Microfibers, Microplastics, Oceans and Seas, Plastics - analysis, Plastics - metabolism, Polyethylene terephthalate, Polymer industry, Seafood - analysis, Water Pollutants, Chemical - analysis...