Microplastic contamination in endemic species: a case study on ginger prawn, Metapenaeus kutchensis

Abstract

Plastic pollution has increased globally in recent decades and is considered an imminent risk to human health and marine life. This study was carried out to assess microplastic (MP) contamination in the gastrointestinal tract (GIT) of the commercial marine prawn Metapenaeus kutchensis sampled from three foremost fishing centers in Gujarat. The samples were dissected in the laboratory, and the GIT was digested with 10% KOH. The MPs were floated using ZnCl₂ in accordance with the density gradient technique. Subsequently, filtration was carried out, followed by the observation of the obtained residue using a stereo microscope. Subsequently, MPs underwent chemical and physical characterization (total count, shape, size, and color). From 135 individuals, a total of 173 MPs were identified, with 100% contamination in all the studied individuals. It was demonstrated that the average MP abundance in the prawn's GIT was 3.94 ± 2.40 MPs per g (ranging from 1.68 ± 0.87 to 5.40 ± 1.90 MPs per g). Higher MP contamination was recorded in the post-monsoon period, followed by monsoon and pre-monsoon periods. MP contamination varied significantly between study sites. The abundance of MP contamination in sediment and water was recorded as 11.25 ± 12.23 MPs per kg and 1.38 ± 0.78 MPs per L, respectively. The findings of regression analysis between the body length and the abundance of MPs revealed no significant correlation. PCA showed varied environmental factors influencing prawn MP contamination. Fibers with blue and black colours were reported as the most commonly accounted MPs. Size-wise, the 1–2 mm size class was recorded to be pre-dominated in all study sites. The extracted MPs were found to contain polyethylene, polyethylene terephthalate, and polypropylene in their chemical compositions. The study of MP contamination in endemic species revealed the impact of pollution on sensitive, unique organisms, aiding biodiversity conservation and raising awareness of local ecosystem health. The current study can offer important background information for future investigations as well as provide data for management and conservation of marine eco-systems in Gujarat for safeguarding their health.