Fish assemblages of Venice Lagoon shallow waters: an analysis based on species, families and functional guilds

The fish assemblages in the Venice Lagoon were studied from March to December 2001, by surveying fyke nets in three shallow water areas, which were located at different distances from the marine inlets and characterized by different types of substratum. The fish abundance was standardized as catch per unit effort (CPUE) and the fish community was analysed both in terms of its taxonomic and functional composition (by making use of both ecological and dietary preference guilds). A total of 25,177 individuals, belonging to 43 fish species and 21 families, was recorded, and the differences in the fish assemblages both in terms of composition and seasonal patterns among the three areas investigated were revealed. The composition of the fish assemblages differed markedly among the three sampling areas at the levels of species and families, whereas the spatial differences were less evident in terms of functional guilds composition. These spatial differences can be ascribed to both habitat differences and geographic location of the areas investigated, especially the distance from the sea inlets. The preliminary investigations regarding the relationship between the structure of the fish assemblages and the environmental parameters suggested the importance of certain physical factors (such as the salinity, temperature and hydrological conditions) with regard to the structuring of the ichthyological community. The use of these results regarding the management and conservation of the Venice Lagoon is also proposed and discussed in this paper.