J. Limnol., 2013; 72(1): 184-200 DOI: 10.4081/jlimnol.2013.e15 INTRODUCTION Wetlands are habitats suitable for many species of benthic macroinvertebrates (Biggs et al., 1994). The com- munities are influenced by many environmental factors; the surrounding landscape and the duration of flood are of special importance, allowing the maintenance of a well- diversified fauna (Minelli, 2001; Della Bella et al., 2005). In the past, Northern Italy was characterised by large al- luvial areas, but at present, the development of densely colonised, industrialised, and cultivated areas has strongly reduced the presence of natural temporary ponds (Fasola, 2003; Stoch, 2005). In this context, the widespread occur- rence of rice agroecosystem in the Po river basin could surrogate the loss of natural wetlands (Lawler, 2001; An- gelini et al., 2008) and could be evaluated as a hot spot of diversity in a highly impacted plain. Moreover, we must consider that rice paddies are not isolated but they are con- nected by channels, which could be of particular interest in supporting and enhancing rice field biodiversity. Rice agroecosystem is subject to different anthro- pogenic effects that can vary significantly within the country and can have effect on macroinvertebrate com- position. They are principally due to the source and the regularity of water supply, soil permeability and different environmental factors (Moormann and van Breemen, 1978). It must not be overlooked that the natural water cycle in rice fields is strongly altered because paddies are flooded during the rice growing period and dries up in au- tumn and winter, while natural ponds are generally richer in water during colder seasons. The absence of water in rice field in this period is unfavourable to the development of many species which overwinter in the preimaginal stage in wetlands (Suhling et al., 2000). Besides, one must consider that the flooding period is strongly influenced by management techniques (e.g. seeding technique or water removal to allow operations such as weed and eventually insecticide treatments). The shortage of the period of water permanence can affect the survival of species with longer cycle (Bazzanti et al., 2003; Caramujo and Boavida, 2010). Water in rice fields is also subject to quick physical and chemical changes (Panizzon et al., 2012). Thermal fluctuations are directly affected by the height of rice plants, with the consequent creation of a mi- croclimate with aspects of tropical and subtropical areas with small thermal excursions also at northern latitude (Confalonieri et al., 2005). Al-Shami et al. (2010) re- ported the influence of agronomic practices on dissolved oxygen, pH, conductivity, phosphate and nitrate. As a re- sult, the rice agroecosystem is a very complex environ- ment and all small modifications can have direct effects on macroinvertebrate communities. Benthic macroinvertebrates in Italian rice fields Daniela LUPI, * Anna ROCCO, Bruno ROSSARO University of Milan, Department of Food, Environmental and Nutritional Sciences (DeFENS), Via Celoria 2, 20133 Milano, Italy. *Corresponding author: daniela.lupi@unimi.it ABSTRACT Rice fields can be considered man-managed temporary wetlands. Five rice fields handled with different management strategies, their adjacent channels, and a spring were analysed by their benthic macroinvertebrate community to i) evaluate the role of rice agroe- cosystem in biodiversity conservation; ii) find indicator species which can be used to compare the ecological status of natural wetlands with rice agroecosystems; and iii) find the influence of environmental variables on biodiversity. Different methods of data analysis with increasing degree of complexity – from diversity index up to sophisticated multivariate analysis – were used. The investigation provided a picture of benthic macroinvertebrates inhabiting rice agroecosystems where 173 taxa were identified, 89 of which detected in rice paddies. Among them, 4 phyla (Mollusca, Annelida, Nematomorpha, and Arthropoda), 8 classes (Bivalvia, Gastropoda, Oligochaeta, Hirudinea, Gordioida, Insecta, Branchiopoda, and Malacostraca), 24 orders, 68 families, 127 genera and 159 species have been found. Ten threatened and 3 invasive species were detected in the habitats examined. The information obtained by the different methods of data analysis allowed a more comprehensive view on the value of the components of rice agroecosystems. Data analyses highlighted significant differences between habitats (feeding channel and rice field), with higher diversity observed in channels, and emphasised the role of the water chemical-physical parameters. The period of water permanence in rice fields resulted to be only one of the factors influencing the community of benthic macroinvertebrates. The presence of rare/endangered species allowed characterising some stations, but it was less informative about management strategies in rice paddies because most of these species were absent in rice fields. Key words: biodiversity indices, faunistic composition, water parameters, wetlands, rice fields, self-organising map. Received: August 2012. Accepted: November 2012. Non-commercial use