Improving microplastic biomonitoring in sandy beaches through field and laboratory approaches: effects of short-term temporal variability on the design of monitoring programs

Abstract

Microplastic pollution poses severe threats to the marine environment and, for this reason, global efforts have been undertaken to develop monitoring schemes to assess trends in microplastics distribution in sediments, water column and biota. However, determining appropriate monitoring strategies is complex due to the high variability of microplastics abundance in small spatial and temporal scales, especially in highly dynamic environments, such as sandy beaches. Evaluating biota responses to this short-term variation in microplastics availability is crucial to establish an adequate sampling periodicity for biomonitoring that enables the understanding of the ecological significance of microplastic contamination. In this context, it is expected that assessments using organisms provide less variability than abiotic compartments since microplastics amount in tissues depends on the uptake, retention and depuration rates. This project aims to: 1) quantify and identify the polymer types in samples of invertebrates from Brazilian beaches collected for the PhD project; and 2) evaluate the short-term dynamics in microplastic abundance in different matrices (sediment, water and clams) to recommend a better temporal sampling frequency for beach monitoring. The second objective will be executed using: a) field approach, evaluating microplastic abundance in the natural environment through a periodic sampling of the three matrices, and b) experimental approach, evaluating clams' responses to a known concentration of microplastics exposure in the laboratory (single vs. periodic exposure). Microplastics concentration will be analyzed following well-established protocols in the literature. The outcomes of this project will provide new recommendations related to the use of marine organisms and sampling periodicity for microplastic monitoring. (AU)