Merja Zerga lagoon: study of the functional structure and bioassessment of the ecological quality of benthic communities

The study of functional diversity based on trophic groups showed a spatial stratification of benthic macrofauna at Merja Zerga lagoon. Thus, from downstream to upstream, we demarcate a successive dominance of suspension feeders, subsurface deposit feeders, grazers and surface deposit feeders, respectively. The surface deposit feeders and carnivores dominate the species richness and the biomass of the structure while grazers dominate the abundance. This structure appears to be related to the diversity of habitats, sediment granulometry and abundance of seagrass and algae. The evaluation of the state of the ecological quality of the lagoon was performed using four biotic indices BOPA, AMBI, M-AMBI and ITI. Accordingly, we highlighted a first evaluation of the lagoon ecological status on the basis of benthic macroinvertebrates. Therefore, it appeared that benthic communities of the Merja Zerga are not severely disturbed as 74% of stations were classified as acceptable ecological status. Received 11 Nov 2016, Revised 27 Jan 2017, Accepted 29 Jan 2017