Microplastic levels and sentinel species used to monitor the environmental quality of lagoons: A state of the art in Italy

Lagoons play an important role in providing a variety of ecological services. They provide important habitats for several plant and animal species, also acting as natural filters that regulate water quality. Microplastic (MP) pollution has become a global environmental problem that warrants in-depth studies to understand its impact on socioeconomically and ecologically important areas such as lagoon systems. However, there is a notable lack of data on the occurrence of MPs in Italian lagoon systems, highlighting the need for monitoring and assessment. In this review, peer-reviewed studies from Google Scholar and Scopus databases were examined (n = 10), reflecting the current knowledge on the occurrence of MPs in Italian lagoon systems. A high degree of methodological heterogeneity was recorded, making difficult a meaningful comparison and draw comprehensive conclusions about the occurrence of MPs. Alarmingly, in Italy, only 9 of more than 100 coastal transition ecosystems have been monitored for MP pollution, leaving a significant number unexplored and inadequately studied. In addition, most studies have focused primarily on organism analysis without simultaneously examining the presence of MPs in water and sediments, making it difficult to establish links between MP pollution in abiotic and biotic compartments. To address these gaps, we extended the literature review to research performed worldwide to identify potential organisms suitable for monitoring MPs in lagoons and nearshore transition ecosystems. As observed in many studies, our results highlight the urgent scientific need to standardize methods, procedures, and sampling designs to facilitate comparability and improve the robustness of future research in this area. Overall, this review sheds light on the MP occurrence in Italian lagoon systems, highlights the limitations of existing studies, and emphasizes the urgency of adopting standardized approaches for consistent monitoring and assessment. By addressing these research gaps, we can improve our understanding of MP pollution in lagoons and develop effective strategies to protect these important ecosystems.