Microplastics are plastic fragments smaller than 5 mm. They spread through the air and are carried by rain, rivers, groundwater and floods. In laboratory experiments such particles harm many species, and there is a suspicion that they are also dangerous in the wild. However, until now it was unclear whether stronger contamination of an area means higher accumulation of plastic in the body of a particular animal.
An answer to this question was provided by work in the journal Nature. An international team led by wildlife conservation specialist Dr Marcia de Almeida Monteiro Melo Ferraz (University of British Columbia, Kelowna, Canada) studied lowland tapirs (Tapirus terrestris) and giant anteaters (Myrmecophaga tridactyla) in Brazil. The analysis included 26 tapirs and 21 anteaters from the Amazon, Cerrado and Pantanal regions.
The scientists combined three types of data: blood tests for microplastics, GPS tracking of the animals' movements and detailed maps of landscape disturbance. To process the tracks they used the open-source program ctmm (continuous-time movement modeling). It reconstructs an animal's path between two GPS points and helps to understand where and how much time the animal spends. This tool was developed by the group of Professor Justin Calabrese at the Center for Advanced Systems Understanding (CASUS) at the Helmholtz Institute in Dresden-Rossendorf (HZDR), who became one of the co-authors.
The result: microplastic particles were found in 43 of the 47 animals. The concentration in the blood was noticeably higher in those whose home ranges are more affected by humans, and in those that lived closer to waste-handling facilities. This is a statistical association, not proof that proximity to people itself causes plastic accumulation - however, the authors emphasize that they have shown such a relationship for terrestrial mammals for the first time.
A separate surprise came from the Pantanal - a remote and outwardly pristine wetland region. Microplastics were found in all the animals caught there, including individuals that lived more than 65 km from human infrastructure. True, the concentrations in the blood were substantially lower, and according to the GPS data these animals did not directly encounter human-modified landscapes. This means plastic is widely dispersed even in relatively remote terrestrial ecosystems.
The authors conclude: improving waste management around settlements could noticeably reduce microplastic levels in wild animals. This is especially important for fast-developing countries like Brazil, where waste-recycling infrastructure lags behind the growth of settlements into new territories. Buffer zones are useful in protected areas, and in local efforts even simple measures to eliminate the main sources of nearby pollution help.