Variability in Macrobenthos Communities in the Valli di Comacchio, Northern Italy, a Hypereutrophized Lagoonal Ecosystem

The composition and the community structure of the macrobenthic assemblages in different habitats in the Valli di Comacchio (northern Italy, Adriatic Sea) was investigated. Nine stations in three major basins were selected and sampled quarterly from November 1997 to September 1998 for macrofauna and environmental parameters. Sampling stations were located along a gradient of macrophytic coverage and sediment texture. Data were subjected to ANOVA and multivariate analysis to discriminate between habitats, sites, and seasonality on their faunal attributes. Water variable values were typical of eutrophic areas. A total of 37 macrobenthic taxa were identified, and differences in the species complement were found between the various habitats within each site. Unvegetated habitats were generally found quite impoverished. Community structure of the macrobenthos at the most marine station was ruled by the cycle of Ulva rigida. Trophic guild analysis revealed a well structured community thriving in theRuppia -vegetated habitat. The persistence, in the marginal Ruppia -vegetated habitat, of such a well structured macrobenthic community, suggests that, notwithstanding the loss of structuring capacity of the habitat exhibited by innermost areas, this lagoonal ecosystem could be resilient enough to recover to its former ecological value.