Structural And Functional Biodiversity Of Soft Bottom Macrobenthic Assemblages In Coastal Areas: a multiscale spatial approach

Macrobenthic communities are essential components in soft sediment environments, playing several functional roles in ecosystem processes such as detrital decomposition, nutrient cycling, dispersion and burial, energy flow to higher trophic levels. Since macrobenthic communities are strongly related to sediments which are possible sources of organic enrichment and pollution, therefore they are considered highly suitable to assess environmental quality and detect several kinds of natural and anthropogenic stresses. A detailed knowledge of both structural and functional features of macrobenthic communities is necessary not only to evaluate the environmental quality of investigated areas but mostly to adequately manage coastal ecosystems. Understanding relationships between these two components of biodiversity should allow to prefigure realistic consequences of habitat degradation and changes in species composition, which in turn may impair the ecological functions performed by species. Spatial variability is a common feature of many natural communities, even in soft sediments which are usually considered as homogeneous habitats. In particular, patchiness of soft bottom macrofaunal assemblages has been described at several spatial scales, both small-medium and larger ones. The hierarchical sampling approach is suggested as the most appropriate method in order to estimate the proportion of variability associated with each scale examined. On these bases, the present study provides a detailed description of macrobenthic assemblages inhabiting shallow sandy sediments along the whole Tuscan coast using a hierarchical sampling design.