Do people have the power? Citizen Science and Environmental Monitoring: insights from the Ombrone River basin and European experiences

Freshwater ecosystems are widely threatened by multiple anthropogenic pressures, while conventional monitoring programmes remain limited in spatial and temporal coverage. In this context, Citizen Science (CS) has emerged as a promising approach to complement traditional monitoring, although concerns regarding data quality and methodological consistency persist. This PhD thesis provides an evaluation of participatory approaches for assessing the ecological quality of riverine ecosystems, based on a series of targeted field experiments conducted across different biological components. The research initially focuses on the development and validation of a simplified CS protocol using benthic macroinvertebrates as habitat quality bioindicators. The results showed that CS-based methods can produce ecologically meaningful results comparable to expert-based assessments, provided that robust standardisation of sampling procedures and experimental design is ensured (Chapter 1). A comparative analysis of European simplified macroinvertebrate protocols further reveals that methodological differences in sampling design influence data comparability, highlighting the need for further investigation to harmonise approaches at a continental scale (Chapter 2). Expanding beyond aquatic biota, the thesis evaluates a novel protocol for riparian vegetation monitoring, showing that volunteers are capable of generating high-quality data when protocols are carefully designed to minimise observer bias. The findings also emphasise the importance of targeted training and iterative feedback for improving data reliability (Chapter 3). Finally, the thesis presents the CS4Rivers project, a transdisciplinary framework integrating citizen participation, scientific research, and environmental monitoring, within which the aforementioned CS protocols were developed and/or tested. The results obtained from citizen-generated data highlight the potential of the simplified protocols as effective early warning tools, capable of capturing spatial heterogeneity and ecological gradients within the study area (Chapter 4). Overall, the thesis demonstrates that Citizen Scientists can generate reliable, high-quality data when supported by robust, standardised protocols and continuous training with iterative feedback. Practical field experience further enhances volunteer performance over time, underscoring the importance of long-term, well-structured CS programmes. The integration of participatory and traditional monitoring approaches could provide a more comprehensive assessment of ecosystem quality. Collectively, these findings strengthen the scientific basis for the inclusion of CS within official freshwater monitoring frameworks and support its role in long-term environmental assessment and management.