Characterisation of Ingested Microplastic Particles and Textile Microfibres in the Gastrointestinal Tract of Demersal Fish from a Peri-Urban Open Access Lagoon in Lagos Nigeria

Background and Objective: Information about microplastic (MP) prevalence in fishes’ resident in West African waters is still patchy at best. This study was initiated to study the presence, abundance and species distribution of microplastics (MP) and fibres (MF) in fish caught from a lagoon bordering the mega city of Lagos in Southwestern Nigeria, intending to fill the knowledge gap as concerns their presence and species prevalence in Nigerian waters. This study aimed to describe MP and MF numbers and, types in the gastrointestinal tracts (GITs) of fish from Lagos. Materials and Methods: The gastro- intestinal tracts of sixty-eight individuals from six genera were analysed. Evidence of microplastic ingestion, retention and abundance. physical characteristics and types were also determined. Primary MP Identification and physical characterisation was done visually using microscopes with camera attachments. Suspect MP were physically categorized according to colour, size and debris type. Polymer identification was done using the micro-FTIR protocol. Results: A total of 62 suspect microplastics were recovered in total. The mean number of MPs ingested per individual was 2.4 and mean MP length was >1 µm (816 µm). Twenty particles were successfully analysed by micro-FTIR, with Micro fibres being the predominant forms detected, composed mainly of cotton (31%), natural (5%), cellulose (23%), rayon (26%), polypropylene (3%), (PET (5%), polyacrylate (3%), nylon (3%) and wool (5%). Fibres with a preponderance of blue fibres (53%) followed by black fibres (26%), red fibres (8%), clear/white/grey fibres (8%) purple and brown 2% each. Conclusion: Omnivorous/carnivorous and mixed-mode feeder species consumed/retained the highest number of microplastics. Potential sources of microfibre/plastic inputs into the local catchment are suggested.