Microplastics spatiotemporal distribution and variability in marine habitats along the Western Mediterranean coastal waters

Abstract

[eng] Microplastics (< 5mm) represent a hazard to the marine environment, particularly in the Mediterranean Sea, generating multiple impacts on its habitats, from the sediment to the surface, including ingestion by biota. Therefore, a holistic approach is required to properly evaluate seas’ health and the repercussion microplastics have across marine ecosystems, rather than assessing microplastic pollution independently by unique habitats. Given the lack of research considering this global vision, in addition to the intense anthropic pressures exerted along Mediterranean coastal areas, it is urgent to understand the plastic cycle. Thus, in this research, the spatiotemporal variation of microplastics at micro-, mesoand macroscale along sea surface waters, sediments and biota have been assessed across the Spanish Western Mediterranean coast through samples from 2017 to 2023. The innovative methodology developed responds to the variability in microplastic distribution due to factors such as sampling effort and techniques. Consequently, the use of quartiles on microplastic’s abundance, associated to multivariate analysis, and the ecological quality index promoted by the Barcelona Convention, were evaluated to offer a standardized and integrated measure of microplastic abundance (including fibres) that allows for a general comparison among different areas and habitats, while keeping each region’s spatiotemporal variability. Results describe the Spanish Western Mediterranean with a quartile classification of “Moderate” according to Fibres accumulation in sediment and sea surface, and a “Low” quartile accumulation with a temporal stability for MPs accumulation in sediment. Furthermore, surface waters displayed a generally constant “Poor” and “Bad” environmental status regarding the traffic light index classification from the Barcelona Convention, rather than permanent, localized plastic hotspots regarding MP contamination. Overall, this study offers a new methodology for assessing microplastics’ spatiotemporal distribution, particularly useful in characterizing the plastic cycle.