Occurrence of microplastics in freshwater gastropods from a tropical river U-Taphao, southern Thailand

Abstract

Background Microplastics (MPs) are pollutants in rivers and marine environments. Rivers can be sources and sinks of MPs that enter the biota. Previous studies focusing on freshwater species are quite limited, especially for gastropods. Freshwater gastropods are essential to aquatic ecosystems because they are food to other aquatic animals, such as fish, shrimp, and crabs. They are a crucial link in the food chain between water resources and human food. Therefore, this study aimed to investigate MP accumulation in freshwater gastropods, commonly known as snails (Filopaludina sumatrensis speciosa and Pomacea canaliculata), in a river flowing into a shallow coastal lagoon. Method In this study, snail tissue samples were digested with 30% hydrogen peroxide. The mixture was heated at 60 °C for 24 h. MP particles were identified, counted, and characterized (shape, size, and color) by visual identification under a stereomicroscope. Furthermore, polymer-type identification was performed using Fourier transform infrared spectroscopy (FTIR). Analysis of variance (ANOVA) was applied for the statistical analysis. Results The MPs found were as follows: 4.76 particles/individual were found in F. sumatrensis speciosa upstream, 5.20 particles/individual were found in F. sumatrensis speciosa downstream, 7.28 particles/individual were found in P. canaliculata upstream, and 4.00 particles/individual were found in P. canaliculata downstream. It was found in the two-way ANOVA that the accumulation of MPs in gastropods was affected by species and study sites (upstream and downstream). There was a significant difference in the amount of MPs in P. canaliculata between upstream and downstream sites (p = 0.003). Fibers were the most common MPs in both species. Moreover, P. canaliculata upstream had the most significant amount of MPs. The smallest amount of MPs was recorded for P. canaliculata downstream, but there was great diversity in shape, size, and polymer type. MPs sized 500 μm–1 mm were the most common in both species. Fourier transform infrared spectroscopy revealed six polymers: poly (ethylene terephthalate), polypropylene, rayon, polyethyleneimine, polyamine, and poly (propylene: ethylene). The occurrence of MPs in gastropods is alarming for food security in Thailand. The results of this study can be used to support baseline data on MP accumulation among freshwater gastropods.

Terrestrial wildlife as indicators of microplastic pollution in western Thailand

“…PET was detected in rice field-dwelling Pantala sp . ( Maneechan & Prommi, 2022 ), and two snail species ( F. sumatrensis speciosa , P. canaliculata ) from the U-Taphao River ( Jitkaew et al, 2023 ). PP contamination was observed in Pantala sp .…”

“…PP contamination was observed in Pantala sp . from rice fields ( Maneechan & Prommi, 2022 ) and the two snail species ( Jitkaew et al, 2023 ). Rayon was found in mussels, clams ( Chinfak et al, 2021 ), P. canaliculata , F. sumatrensis ( Jitkaew et al, 2023 ), and Giant freshwater prawns ( Macrobrachium rosenbergii ) ( Tee-hor, Nitiratsuwan & Pradit, 2023 ).…”

“…from rice fields ( Maneechan & Prommi, 2022 ) and the two snail species ( Jitkaew et al, 2023 ). Rayon was found in mussels, clams ( Chinfak et al, 2021 ), P. canaliculata , F. sumatrensis ( Jitkaew et al, 2023 ), and Giant freshwater prawns ( Macrobrachium rosenbergii ) ( Tee-hor, Nitiratsuwan & Pradit, 2023 ). PU contamination was noted in the two fish species and the two snail species ( Yasaka et al, 2022 ), while Giant freshwater prawns were also contaminated with cotton ( Tee-hor, Nitiratsuwan & Pradit, 2023 ), PE ( Reunura & Prommi, 2022 ), and PES ( Tongnunui et al, 2022 ).…”

“…Despite this broad coverage, there is a significant gap in research on MP accumulation in terrestrial wildlife, with the majority of studies focusing on invertebrates and fish in freshwater environments. These studies have examined insects ( Thamsenanupap, Tanee & Kaewsuk, 2022 ), gastropods ( Jitkaew et al, 2023 ; Yasaka et al, 2022 ), and freshwater shrimps ( Tee-hor, Nitiratsuwan & Pradit, 2023 ; Reunura & Prommi, 2022 ; Tongnunui et al, 2022 ). Among terrestrial vertebrates, the research has been limited to freshwater fish ( Kasamesiri & Thaimuangphol, 2020 ; Seetapan & Prommi, 2023 ), with no studies conducted within protected areas (PAs), despite their critical role in biodiversity conservation ( Naughton-Treves, Holland & Brandon, 2005 ).…”