Abstract
We propose an extension to the metacommunity (MC) concept and a novel operational methodology that has the potential to refine the analysis of MC structure at different hierarchical levels. We show that assemblages of species can also be seen as assemblages of abstract subregional habitat-related metacommunities (habMCs). This intrinsically fuzzy concept recognizes the existence of habMCs that are typically associated with given habitats, while allowing for the mixing and superposition of different habMCs in all sites and for boundaries among subregions that are neither spatially sharp nor temporally constant. The combination of fuzzy clustering and direct gradient analysis permits us to 1) objectively identify the number of habMCs that are present in a region as well as their spatial distributions and relative weights at different sites; 2) associate different subregions with different biological communities; and 3) quantitatively assess the affinities between habMCs and physical, morphological, biogeochemical, and environmental properties, thereby enabling an analysis of the roles and relative importance of various environmental parameters in shaping the spatial structure of a metacommunity. This concept and methodology offer the possibility of integrating the continuum and community unit concepts and of developing the concept of a habMC ecological niche. This approach also facilitates the practical application of the MC concept, which are not currently in common use. Applying these methods to macrophytobenthic and macrozoobenthic hard-substrate assemblages in the Venetian Lagoon, we identified a hierarchical organization of macrobenthic communities that associated different habMCs with different habitats. Our results demonstrate that different reference terms should be applied to different subregions to assess the ecological status of a waterbody and show that a combination of several environmental parameters describes the spatial heterogeneity of benthic communities much better than any single property can. Our results also emphasize the importance of considering heterogeneity and fuzziness when working in natural systems.
Highlights
Spatial heterogeneity in geomorphologic, hydrodynamic and biogeochemical properties, as well as in the composition and structure of biological communities, are common features of coastal and estuarine systems [1,2]
The perception that in large and complex systems the different subareas characterized by different abiotic properties are dominated by different communities is so common among scientists that it has become embedded in marine conservation directives
Ethics Statement No specific permits were required for the described field studies because the study was funded and commissioned by the Magistrato alle Acque di Venezia – the Water Venice Authority, which regulates all activities in the lagoon
Summary
Hydrodynamic and biogeochemical properties, as well as in the composition and structure of biological communities, are common features of coastal and estuarine systems [1,2]. The perception that in large and complex systems the different subareas characterized by different abiotic properties (habitats) are dominated by different communities is so common among scientists that it has become embedded in marine conservation directives (e.g., the Water Framework Directive). These directives require that the evaluation of the ecological status of a waterbody be conducted by comparing different waterbodies against different reference systems, depending on habitat type. It is relatively straightforward to explore relationships between species distribution and environmental factors [3,4], exploring and modeling the quantitative relationships between environmental variables and community spatial structure is much more challenging
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
