Plastic pollution especially microplastics (MPs) (<5 mm) in aquatic ecosystem is an ongoing global issue that posing significant threats to aquatic species consequences coastal and marine environment and human health. The present study aims to investigate the presence and abundance of MPs in commercially important six finfish and two shellfish. Finfish species included Tuna (Katsuwonus pelamis), Hilsa (Tenualosa ilisha), Seabass (Lates calcarifer), Ribbon fish (Trichiurus lepturus), Bombay duck (Harpadon nehereus), and Jewfish (Johnius argentatus ) species and shellfish included s hrimp (Macrobrachium rosenbergii) and Prawn (Penaeus monodon). Both shellfish samples were collected from wild (capture) and farmed (culture) sources in Chittagong, and finfish samples were collected from the fish landing center of Kuakata Bangladesh. E ach finfish and shellfish samples were of n=10, where shellfish samples were in equal representation from wild and farmed sources. Then the muscle, g ill, gut/g astrointestinal tract (GIT) of each sample were examined for MPs. For extraction of MPs, two-step digestion methods were applied including alkali (KOH) and peroxide (H2O2 ), followed by vacuum filtration and microscopic identification. Fourier-Transform Infrared Spectroscopy (FTIR), heatmap, cluster analysis and principal component analysis (PCA) conducted to identify polymer compositions and correlation among MPs.
The result revealed that in case of finfish a total of 7085 MPs were identified where tuna contained the highest and bombay duck had the lowest. On average the MPs abundance per finfish samples were ranged from 1.56±0.39 to 7.16±1.36 MPs/g in muscle, 1.91±0.32 to 4.46±0.75 MPs/g in the gut, and 2.36±0.24 to 6.53±1.58 MPs/g in gill. In case of shellfish, MPs contents were lower in prawn than the shrimp for both wild and cultured samples. Among the examined organs, GITs were more affected by MPs, followed by gills and muscle of the shellfish, irrespective of the culture and capture sources. Among distinct groups, 1-5 mm sized (33.33-62.78%), white/transparent colored (18.45-54.63%), filament shaped (75.00-94.71%), and fiber types (73.21-94.71%) were dominant. FTIR test confirmed 58.89% polyethylene, 21.67% p olypropylene, 17.22% polyester, and 2.22% of non-plastic variants in MPs. Multivariate analysis showed four clusters: clusters 1 and 3 on their own , and 2 and 4 cluster combined two species based on the 50% similarity matrix. In addition, PCA percentage varied from 46% to 69.4% in PC1, and 14% to 22.9% in PC2 revealing the dominance of the factorial dimensions by showing positive-negative distance. The findings provided a comprehensive understanding of MPs extent, source, and characteristics in commercially significant finfish, and shellfish from the coastal area of Bangladesh , thus effective policy implications demanded to avoid plastic pollution in consequences mitigate the potential risks to human health at local and global level .