Fast responses, rich insights: Optimizing experimental stream studies using periphyton for comprehensive environmental assessment

Experimental streams (ESs) are enclosures of fluvial ecosystems designed as flume microcosms to simulate flowing waters and assess environmental disturbances on aquatic communities' structure and function under controlled conditions. This study presents an ES system that combines ecological relevance with reliability in a compact design, offering rapid responses to iron ore tailings. The system used periphyton biofilm as a bioindicator in a recirculating flume microcosm over 65 d. Periphyton is a key bioindicator, representing critical aquatic metabolic processes such as primary production. The system includes artificial glass channels, microscope slide substrates, and recirculating pumps. It was developed with replicates, three controls, and three treatments, each consisting of a main channel and a water reservoir, for a total volume of 10.0 L. Six sampling campaigns evaluated periphyton biofilm and water quality indicators under acute, short, and long-term exposures. The system's reliability is ensured by standardizing setup conditions, maintaining river water properties, ensuring uniform flow, and standardizing slide sampling. Realism is achieved by renewing large water volumes, regular inoculation of periphyton propagules, and the appropriate sampling frequency for periphyton and water quality. The results showed that the ES, a simple and low-cost system (US$569), was sensitive to indicators throughout the exposure period. This approach is practical for assessing various aquatic stressors.