Tuesday, June 5, 2007
493

Thermal Gradient and Water Levels in the Sub-Substratum of the Po River (Italy):

Tiziano Bo1, Stefano Fenoglio1, Paolo Gay, PhD2, and Davide Ricauda Aimonino2. (1) Dipartimento di Scienze dell'Ambiente e della Vita, University of Piemonte Orientale, Via Bellini 25, Alessandria, 15100, Italy, (2) DEIAFA, University of Torino, Via Leonardo da Vinci 44, Grugliasco, Italy

Temperature and water levels are environmental elements of main importance in lotic systems, where they strongly influence physical, chemical and biological processes. This is particularly relevant in intermittent rivers, where gravel bed environments could dramatically change in different seasons. In this study we investigated the relationships between abiotic parameters, such as temperatures at different levels and hyporheic streamflow patterns, and biotic elements, such as the structure and composition of the macrobenthic community. The study was conducted in the upper Po river (NW Italy), in a reach subject to frequent summer droughts. Abiotic parameters were collected using apposite dataloggers and sensors, buried in the stream bed, for a 24-months period. All devices were buried at different profundities in some 90 cm depth pits, dug with an excavator in a uniform, large riffle. Macroinvertebrates were collected at three different levels by using colonisation traps. We collected 1389 organisms, belonging to 43 taxa. The results of this study show how gravel bed temperature and presence of hyporheic water flow strongly influence both densities and richness of benthic assemblages in the sub-substratum.

 


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