Bridging the Laboratory–Field Divide: Challenges and Opportunities in the ALPSTREAM Eco-Hydraulic Experimental Outdoor Mesocosm

The use of mesocosms in stream ecology has long attracted the attention of researchers due to the clear advantages these systems offer for manipulative experiments. Despite some limitations, they provide an effective way to create semi-natural conditions in which selected parameters can be artificially controlled. This study presents the ALPSTREAM eco-hydraulic laboratory, a mesocosm system designed to mimic the conditions of an alpine stream (Ostana, NW Italy). The structure of this system is unique and consists of six 25-m-long flumes, fed directly by the Po River and equipped to regulate key hydraulic parameters. The paper describes the structure of this system and presents two case studies to illustrate some potential applications. The first aimed to analyze the impact of different aquatic insects (scrapers) on periphyton dynamics. The second tested the feasibility of the flumes for the ex situ breeding of a threatened fish species, the European bullhead (Cottus gobio L.). The purpose of this paper is to raise awareness of this facility and make it available to researchers interested in eco-hydraulic studies in mountain environments.