Bioindicators: Promising tools for assessing microplastic pollution and its environmental impacts, A Updated review

Abstract

Microplastic (MP) pollution represents a global threat due to its persistence and ability to adsorb pollutants. This work presents a systematic literature review to evaluate the use of bioindicators in marine, terrestrial, and aerial ecosystems. The PICO methodology was used for the search string, and the PRISMA methodology for article selection in the academic databases Scopus and Web of Science (WoS), resulting in a total of 29 scientific articles. Bibliometric analysis was also performed using the Bibliometrix tool in the R statistical software. The results reveal a clear predominance of research in marine ecosystems, which represent most of the analyzed sample, followed by terrestrial and aerial environments. Regarding representative bioindicators by ecosystem, in the marine environment, bivalves such as Meretrix casta (55.04 ± 32.15 MPs/g) and cnidarians such as Actinia equina and Cassiopea xamachana stand out. In terrestrial environments, annelids such as Eisenia andrei and freshwater fish such as Squalius vardarensis stand out in lotic systems, while in the air, birds such as Apus apus (1.92 ± 0.72 MPs/Ind) are prominent. Regarding flora, the species Acanthus ilicifolius exhibits the highest bioaccumulation recorded in mangrove areas. Morphological analysis confirms that fibers are the predominant form in all the biotic matrices evaluated. However, despite the suitability of these organisms for environmental monitoring, the review reveals that the lack of standardized protocols hinders the comparison of results between regions. Therefore, the urgent need to implement uniform methodologies in future research is highlighted.