Soil arthropods in bioindication and ecotoxicological approach: The case of the extreme environment Mefite (Ansanto Valley, Southern Italy)

Soil arthropods are pivotal in maintaining soil health and serve as sensitive indicators of soil alterations. The soil arthropod community in the Mefite Geological Site (Italy), characterized by a sulphurous lake and intense degassing, was the focus of this study. In details, the objectives were: i) to characterize soil arthropod community at different distances from the Mefite lake; ii) to identify resilient taxa acting as bioindicators to assess soil ecotoxicity. Soil cores were collected at A) 30m, B) 80m, C) 120m away from the lake; soil organic matter (SOM), and pH, ecotoxicity tests (<i>Lepidium sativum</i>: germination index, elongation inhibition; <i>Folsomia candida:</i> survival, reproduction), and identification of soil arthropods (orders, Collembola families, Protura species) have been carried out. Statistical analyses assessed the impact of sulphurous emissions on soil chemistry, ecotoxicity, and arthropod parameters (community structure, taxa associations, biodiversity indices like Shannon and Simpson, and soil biological quality index - QBS-ar). The results showed: no SOM differences; pH: A < B < C; the highest ecotoxic effects were observed in A for both target species; arthropod community composition and QBS-ar varied notably in A compared to C, with the lowest soil biodiversity found in A. Hypogastruridae (Collembola) showed a clear association with A, while Protura were notably absent in A. This study also provided the first records of 4 Protura species in Campania, updating existing knowledge. Overall, arthropod community biodiversity and composition proved to be effective soil bioindicators in highly acidic conditions, reflecting soil ecotoxicity. In particular, the QBS-ar index demonstrated sensitivity in sulphurous environments.