As marine plastic debris is primarily sourced from terrestrial input, coastal environments are particularly affected by deposition. Because of their pneumatophores, mangroves have been recognized for their importance in confining plastic waste. Crabs are a dominant component of the mangrove ecosystem and play a critical role in maintaining healthy and resilient mangrove forests. Therefore, the presence of debris fragmented from waste, in their habitat is a potential threat. However, the potential ingestion of microplastic pieces by mangrove crabs has not yet been investigated. Here, we quantified microparticles found in the cardiac stomachs and gill chambers of four species of crabs. All specimens collected had anthropogenic microparticles present either via their digestive or respiratory systems. We observed significant variability in the abundance and types of anthropogenic microparticles across sites and species. Interspecific differences appear to be explained by their particular feeding habits, with less selective species ingesting more particles.

Samples were collected near rocks and in mud depending on the species. At least two individuals were collected for each species depending on their appearance on rocks and muds. The number of samples collected for each species are listed in Table 1 on the manuscript. All the samples were collected in a bucket with leaves and sediments to reduce stress of handling. Samples were gently washed with Milli-Q water to remove the mud outside the carapace, legs and chelipeds in the laboratory. They were then frozen at -18 °C immediately for later sample digestion and examination, in which samples were stored in separate clearly named samples bags.

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