Microplastic and microfiber pollution in the Proteus anguinus habitats. Preliminary investigations in the Classical Karst Region

Microplastic (MP) and microfiber (MF) pollution in karst environments is poorly studied. The Classical Karst Region is characterised by the presence of dissolution feature in carbonate rock, protected at European level habitats and species, such as the stygobiont Proteus anguinus. The ecological connections between surface and subterranean karst environments make this area great for monitoring. We collected and investigated water and submerged sediment samples in surface (springs) and subterranean (caves) aquatic environments of the Italian sector of the Classical Karst Region. MPs and MFs from 5 to 0.1 mm were counted and characterized by size, shape, fluorescence and color through optical microscopy, with and without UV light. Spectroscopic analyses were carried out on 10-15% particles. MPs and MFs were found in all examined samples, with an accumulation in submerged sediments. Abundances increased with the decrease of the considered size. Most of the particles were fluorescent under UV light. Fluorescent particles were mainly clear, while non-fluorescent ones were especially dark. Among the analysed MPs, fibre-shape was the main present. Among the analysed MFs, only 10-15% were synthetics; consequently, not-synthetic MFs require more attention and monitoring efforts. Our results show the presence of MPs and MFs in aquatic surface and subterranean karst environments, improving knowledge in water ecosystem pollution. Monitoring this kind of pollutants in karst areas must become a priority, taking into account the ecological connections between surface and subterranean habitats. Stygobionts hosted in karst habitats can assimilate these micropollutants, directly or indirectly, therefore, negative consequences for subterranean water safety should be investigated at all the levels, such as ecological functionality, biodiversity distribution, ecosystem services and human health. Analyses on a greater number of aquatic surface and subterranean habitats should be carried out to better understand this kind of problem, and act for habitat conservation, species protection and water resources management.