Fuzziness and Heterogeneity of Benthic Metacommunities in a Complex Transitional System

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.

Interchange of entire communities: microbial community coalescence

“…an island community is translocated to another island or to the continent). (ii) Community coalescence also allows for and includes the movement and potential mixing of environments, for example aquatic environments [5], and not just the movement of communities between environments. (iii)…”

The non-indigenous Paranthura japonica Richardson, 1909 in the Mediterranean Sea: travelling with shellfish?

“…The samples were collected in 2010 and 2011 (May and September). The Lagoon of Venice is a microtidal lagoon (maximum tidal range: 2.2 m; Flindt et al, 1997), with an area of approximately 550 km 2 , of which nearly 30% is devoted to extensive aquaculture (Bandelj et al, 2012). The lagoon is divided into three hydrographic basins, each of them connected to the sea by a mouth: northern basin (Lido mouth), central basin, including the town of Venice (Malamocco mouth) and Chioggia basin, including the town of Chioggia (Chioggia mouth).…”

An overview of ecological status, vulnerability and future perspectives of European large shallow, semi-enclosed coastal systems, lagoons and transitional waters

“…index of size distribution, Reizopoulou and Nicolaidou, 2007) and composition (e.g. Morgana and Naviglio, 1995;Koutsoubas et al, 2000;Ponti and Abbiati, 2004;Bandelj et al, 2012). A number of indices have also been developed taking into account the benthic macro-fauna (Grall and Chauvaud, 2002;Magni et al, 2005).…”