Contribution a l’étude de la structure trophique et de l’etat écologique du benthos au nord de la lagune de ghar el melh

Abstract

The lagoon of Ghar El Melh (Tunisia) is a Ramsar site subject to Anthropogenic activities. The lagoon ecosystem has been progressively deteriorated since 1994. Its water/sediment quality, its fisheries resources and its biodiversity have been reduced. The present work is a contribution to the study of the functional organization of the benthic macrofauna within the North part of the Ghar El Melh lagoon a few years after the extension of the El Boughaz channel which connects this lagoon to the open sea. Three stations in front of the Ghar El Melh town influences were sampled during spring 2017. Generally the results show a poor diversity of the benthic macrofauna. The registered values of the physico-chemical and sediment parameters show a spatial homogeneity of this part of the lagoon. The trophic organization, in turn, showed the dominance of selective deposit feeders resulting in trophic imbalance despite they are sensible species belonging to the ecological group 1. This allows biotic indices (AMBI and BENTIX) to classify sampled stations at a high ecological status.