Desalination 246 (2009) 190–201 Evaluation of water quality and ecological system conditions through macrophytes Luisa Angela Maggioni a , Diego Fontaneto a , Stefano Bocchi b , Stefano Gomarasca a * a Dipartimento di Biologia, Universita`degli Studi di Milano – Italy b Dipartimento di Produzione Vegetale, Universita`degli Studi di Milano – Italy Tel: +3902503147817; Fax: +390250314764; email: sgomarasca@tiscali.it Received 12 October 2007; revised 17 December 2007; accepted 03 March 2008 Abstract The aim of this research is to define a new Macrophyte Index relevant in the context of the Po Valley. The appli- cation of biotic indexes, as the macrophyte ones, is required by both the Italian and the European law to provide an adequate classification of freshwaters, in association with physical–chemical and hydromorphological data. At the same time, these methodologies, based on the sensibility of macrophytes towards pollution, could be an important mean to evaluate the quality of the waters coming from wetlands, providing information related to the depuration capabilities of these important ecotonal zones. In this study, we elaborate a floristic list of about 340 taxa; moreover, we chose 19 sampling sites, analysed physical–chemical parameters and obtained floristic data. These results, inte- grated by literature information on ecological needs, distribution and rarity of all species, allowed the attribution of indicator values. Thus, two new indexes have been elaborated: Indice Macrofitico di Pianura (I.M.P.), mostly accounting for water quality, and Indice di Biodiversita ` Riparia (I.B.R.), mostly accounting for biodiversity of mac- rophytes on the banks. The efficacy of the proposed indexes has been evaluated by comparing them to analysed physical–chemical parameters and other indexes used in Europe, such as Macrophyte Index Scheme (M.I.S), Indice Biologique Macrophytique en Rivie `re (I.B.M.R.) and Extended Biotic Index (I.B.E.). Keywords: Macrophytes; Macrophyte indexes; Water quality; Biomonitoring 1. Introduction Wetlands are one of the Earth’s richest ecosys- tems, offering ‘‘sanctuary’’ to a wide diversity of plants and animals. In addition, they play other key roles, for example provisioning and maintaining water quality. Nevertheless, despite their importance, wetlands are one of the most degraded ecological systems: more than half of the wetlands worldwide have been destroyed dur- ing the past century. In recent years, a renewed interest on the biological significance of wetlands has led to a better understanding of their economic and cultural value. As a result, an increasing *Corresponding author. Presented at Multi Functions of Wetland Systems, International Conference of Multiple Roles of Wetlands, June 26–29, 2007, Legnaro (Padova) Italy 0011-9164/09/$– See front matter © 200 Elsevier B.V. All rights reserved. 8 doi:10.1016/j.desal.2008.03.052