Analysis of the elements of metacommunity structure in a Mediterranean basin: implications in the framework of global change

Abstract

Metacommunity studies have been gaining in importance in recent decades due to their relevance when interpreting community dynamics. The elements of metacommunity structure (EMS), i.e. coherence, turnover and boundary clumping, are used to assess the assembly of metacommunities. In the present study we analysed the EMS of the Guadiana Hydrographic Demarcation, a prominant seasonal basin located in the southern Iberian Peninsula characterised by a Mediterranean climate, with dry reaches and disconnected pools frequent in streams during the summer. We studied the EMS of the four different taxocoenoses used to assess the ecological status of streams and rivers according to the European Water Framework Directive (diatoms, macrophytes, macroinvertebrates and fishes), both independently of each other and taken together. These analyses were carried out using three different approaches: (1) using a gradient from reciprocal averaging analysis; (2) following a geographical gradient; and (3) following an environmental gradient. We found that the four groups of organisms analysed had either a Clementsian metacommunity structure or a similar structure. When all groups were considered together, the structure of the metacommunity was Clementsian or quasi-Clementsian. Thus, in the framework of the current global change scenario, communities in this basin may be vulnerable to increasing isolation due to more frequent and larger dry periods; consequently, management measures should be considered.