Association of ocean macroplastic debris with stranded sea turtles in the Central Gulf of Thailand

Abstract

The impact of macroplastic debris (>5 mm) on marine life is a global concern but has rarely been investigated in Thailand. This study investigated the relationship between stranded sea turtles and macroplastics in the Central Gulf of Thailand. Records of stranded turtles (n = 388) from 2017-2020 were analysed retrospectively to determine their interaction with macroplastics. In addition, macroplastics collected from the gastrointestinal (GI) tracts of 30 dead stranded turtles and 13 beaches (along a 100 m transect mid-way between high and low tide) between 2019 and 2020 were investigated. Types and composition of macroplastics were identified with the use of a stereomicroscope and Fourier-transform infrared spectrometer. Green turtles Chelonia mydas comprised the majority of stranded turtles (74%, n = 251), and macroplastics (entanglement or ingestion) were the leading cause of death (n = 152). Most stranded turtles were juveniles (65%), and their stranding was significantly correlated with macroplastics (p < 0.001). Juveniles were more prone than adults to become entangled (p = 0.007), while adults had a higher ingestion rate than juveniles (p = 0.009). Plastic fibres were commonly found in the GI tracts (62%, n = 152 of 244) and beaches (64%, n = 74 of 115). Most fibres from the GI tracts (83%, n = 126 of 152) and beaches (93%, n = 68 of 74) were fishing nets made of polyethylene or polypropylene. We conclude that fishing nets are a significant cause of sea turtle stranding in the Central Gulf of Thailand, and this issue requires immediate resolution.

Spatial, Temporal, and Geographical Factors Associated with Stranded Marine Endangered Species in Thailand during 2006–2015

“…Furthermore, sea turtle bycatch also influences the stranding rate [ 19 , 20 ]. Previous studies in Thailand reported that anthropogenic factors, such as plastic waste or fishery activities, were important factors that led to sea turtle stranding [ 12 , 21 ]. In this regard, further research is needed to determine the factor with the greatest effect on sea turtle stranding in Thailand.…”

“…Recently, fishing nets were reported to be associated with the stranding of sea turtles in the Gulf of Thailand. Researchers have also found macroplastic debris in the gastrointestinal tracts of stranded sea turtles [ 12 ]. In other countries, marine mammals have become stranded owing to illness, fisheries activities, and environmental changes [ 13 ], while sea turtle strandings have been reported to be related to anthropogenic factors and illness [ 14 ].…”

Interactions between marine megafauna and plastic pollution in Southeast Asia

“…(For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Investigation of marine vertebrate strandings provides scientists with opportunities to explore the impacts of plastic pollution (Abreo et al, 2019a;Lusher et al, 2018;Nelms et al, 2019;Prampramote et al, 2022). Entanglement can be established through visual observations of animals using images from social media, for example (e.g.…”

“…It transpired through the expert elicitation that cases exist as unpublished for far more species than is currently described in the published literature, although new publications filling in those gaps have emerged since our literature search was performed (e.g. Gajanur and Jaafar, 2022;Ng et al, 2022;Prampramote et al, 2022;Yong et al, 2021). Green and leatherback turtles were the only two species for which published cases of both entanglement and ingestion were available from the SE Asian countries.…”

Microplastics in the Marine Environment: A Review of Their Sources, Formation, Fate, and Ecotoxicological Impact

“…It has been estimated that 10% of the mismanaged plastic waste ends up in the marine environment where it will persist and accumulate over the coming years [7]. The large fragments of plastic debris found in the environment are termed macroplastics [8], and they are known to harm turtles and sea birds via entanglement [9,10].…”