ATTI DEL MUSEO CIVICO DI STORIA NATURALE DI TRIESTE
Abstract
The Orvenco Creek is included in the Basin of Ledra River, that origins partially from an alluvial spring area, placed more northly of the alluvial spring line separating the High plain from the Low Plain of Friuli Venezia Giulia. Fish communities, macrobenthic invertebrates and freshwater macrophytes were investigated to assess the creek ecological status using indices in respect of the D.M. 260/2010 in five samplingstations. Main chemical-physical parameters of water and concentration of main nutrients were monthly measured too. The results showed positive judgements in most cases, especially for LIMeco (high), STAR_ICMi (high) and RQE_IBMR, that showed judgements from good to high and only one case sufficient. The ISECI showed more critical and severe judgements (baed in three stations), due to past and present allochtonous fish species introductions for fisheries. The IFF index was also used, despite not included in the D.M. 260/2010, because it gives valid informationabout the status of frwhwater ecosystems. The IFF index revealed some critical situations not showed by other indices, specially STAR_ICMi and ISECI.
