Using river monitoring data from the Environmental Protection Agencies of Trento and Bolzano, a set of novel statistical analyses were performed to quantify the relation between river biodiversity and river flow characteristics in the Adige River basin (IT).
The first effort provided results regarding the sensitivity of the official bio-indicators to river flow. The data suggest that aquatic invertebrates respond to water quality and only marginally to geo-morphological and flow-related alterations. However, poor ecological conditions were observed where the alteration of river flow was stronger. This suggest that the effects of flow alterations are evident, but only where such alterations are severe.
In a second analysis, a geo-spatial approach was used to assess the spatial patterns in the distribution of biodiversity along the Adige River. The aim was to understand whether biodiversity data could provide insight into the longitudinal connectivity of the river network. Substantial discontinuities in the longitudinal distribution of key aquatic invertebrate groups were observed, suggesting that the longitudinal continuity in the Adige River network has been markedly altered.
In a later stage, a collaboration with hydrologists from the University of Trento, led the development of a large dataset where the 'natural' flow regime of 100 sites across the Adige River was simulated. This allowed us to create the first classification of flow-types in the basin.
Field work included the collection of water quality and invertebrate data from a set of locations up- and down-stream of small hydropower facilities. A total of eight streams were selected based on site accessibility and information on hydropower plants.
Field experiments were conducted in semi-artificial flumes nearby the Fersina stream. The experiments simulated the effects of small water withdrawal on benthic invertebrates. The flumes were naturally colonised by benthic invertebrates from the Fersina stream that feeds the flumes from upstream. Before the start of the experiment, the flumes were virtually divided in two halves. The upstream half served as control, while water was withdrawn from the downstream half (using valves) to simulate the effect of SHP operation. We used a before-after - control-impact (BACI) design with three sampling dates. ‘Sample 0’ was taken initially as control, with no water regulation. Then, water flow was decreased by 50% in the downstream half of each flume. After one week of treatment, ‘Sample 1’ and 'Sample 2" were collected after 1 week and 2 weeks, respectively. Each sample consisted of three replicate baskets taken from each control and treatment. A total of 54 baskets were collected.
Data from the field-work and the experiments are currently being processed. This involves a long process of sorting and identification of the organisms using microscopes.
The project was presented to a wide audience including both technical and non-technical targets. The results were discussed with academic audience at the International Society for River Science meeting in Hamilton (NZ), and to the Eco-Hydraulic conference in Trento. These included an audience with expertise in ecological and hydrological sciences. Dissemination to a non-academic audience involved the participation to the 'Notte dei Ricercatori' at the MUSE and a workshop for students within the Euroflow project. The project was also presented at a stakeholder meeting in Bologna, which included practitioners involved in river restoration.
