CASE STUDY OF THE VERNAVOLA STREAM (SUB-LACUSTRINE TICINO RIVER BASIN, NORTHERN ITALY): THE BIOLOGICAL POLLUTION OF THE ASIATIC CLAM CORBICULA FLUMINEA (MÜLLER, 1774)
The Asiatic clam, Corbicula fluminea, is among the eleven benthic species with the highest impact in the DAISIE list (DAISIE – Delivering Alien Invasive Species Inventories for Europe) because it has both environmental and socio-economic impacts. This paper reports the distribution and the dynamics of a well-established population of the alien bivalve Corbicula fluminea in the Vernavola Stream, a left-side tributary of the sub-lacustrine Ticino River (Pavia, Northern Italy). Additionally, we performed a laboratory experiment to investigate the substrate preference of the invasive bivalve, testing three different types of substrate: medium gravel, fine gravel and medium sand. The highest density of the Asiatic clam was registered in the parts of the stream where the bottom was mainly composed of sand mixed with fine gravel. The results of the experiment indicated a strong preference for sand over other substrates. In order to assess the future development of biological pollution from the Asiatic clam Corbicula fluminea, it would be useful to increase our knowledge of its autoecology and to constantly monitor its population dynamics.