Ingestion of microplastics by the estuarine polychaete, Namalycastis sp. in the Setiu Wetlands, Malaysia

Highlights: • Microplastics were ingested by the deposit-feeder polychaetes in the estuarine area of Setiu Wetlands, Malaysia. • Filaments and transparent microplastics were the most abundant in estuarine polychaete. • Polymers present in the estuarine polychaete were identified as polypropylene and polyamide. • The presence of microplastics could be related to the influx from the open sea and from aquaculture activities. In this study, the ingestion of microplastics by the deposit-feeding polychaete Namalycastis sp. in the estuarine area of the Setiu Wetlands, Malaysia was confirmed. Samples were collected from six stations, covering the wetland from the south to the north, bimonthly between November 2016 and November 2017. Microplastics were extracted from polychaete samples following digestion in an alkaline solution (10 M NaOH). They were identified by physical characteristics (i.e., shape and color under dissecting microscope and scanning electron microscope), and chemical analysis using a LUMOS Fourier Transform Infrared Microscope (μ-FTIR). A total of 3277 pieces were identified, which were dominated by filaments (99.79%) and with the majority transparent in color (84.71%). Most of the microplastics identified were polypropylene (PP) followed by polyamide (PA) based on their main peak in the of μ-FTIR spectrum. Principal component analysis demonstrated the dominance of microplastics at stations 3 and 4 of the sampling area, probably because of the influx from the open sea and from aquaculture. The findings of this research provide baseline information on microplastics ingested by benthic organisms and their fate in the estuarine food web.