Evidence of microplastics in the polychaete worm (capitellids-Capitella capitata) (Fabricicus, 1780) along Thoothukudi region.

Research on the occurrence of microplastics in invertebrates of the Thoothukudi region is limited. Capitellids are non-selective suspension feeders and are usually used as bioindicator of water pollution. Hence, an investigation was carried out to identify the microplastic occurrence in the capitellids (Capitella capitata) (Fabricius, 1780) collected from the Vellapatti and Spic Nagar sites of the Thoothukudi region. Result from this investigation showed the occurrence of 0.21 ± 0.17 items/indiv and a mean abundance of 13.33% in Thoothukudi coast. The mean microplastic abundance in the capitellids was significantly higher in the Spic Nagar (0.26 ± 0.19 MPs/indiv), probably due to the dumping of plastic waste, fishing and recreational activities. However, no significant difference was observed between seasons. Only fragments (Vellapatti 66.66% and Spic Nagar 33.33%) and fibre-shaped microplastics (Vellapatti 50% and Spic Nagar 50%) were identified. The size and colour of the microplastics dominant in both sites were 1-2 mm (Vellapatti 77.77% and Spic Nagar 75%) and blue (Vellapatti 88.88% and Spic Nagar 87.5%), respectively. The results of Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) analysis revealed the presence of polyethylene (PE) and polypropylene (PP) polymers in the capitellids. PE polymer is one of the most common sources of microplastics contamination globally and it is also frequently found in the coastal waters of Thoothukudi. This accounted for the high occurrence of PE polymers in the capitellids with the occurrence rate of 77% in Vellapatti and 58.52% in Spic Nagar. The present study provides baseline data on the occurrence, characterization (shapes, sizes and colours) and qualitative analysis of the microplastics in the capitellids, and their presence was influenced by their non-selective feeding habits. Further, future studies have to be conducted to identify the levels of microplastics in different polychaetes and other invertebrates to better understand the effects of microplastic pollution in invertebrate communities.