Does increased connectivity with the Mediterranean Sea improve the ecological status of the macroinvertebrates in the lagoon of Boughrara (SW Mediterranean)?

Abstract

The lagoon of Boughrara is an almost closed system, with limited hydrological connections with the sea. Over the past several decades, the lagoon has been exposed to increased pollution due to growing human activities in the surrounding area. From 2004–2007, the channel “El-Kantra” connecting the lagoon to the sea has been extended with increased mixing with marine waters. In this work, we monitored the ecosystem of the lagoon after its rapid exposure to development and associated pollution. Two marine surveys were carried out in winter 2010 and then in winter 2013; the sediment was sampled and the principal physical and chemical parameters were measured at 13 stations. Results show that aspects of the environmental quality of the lagoon have improved from 2010 to 2013, most likely due to the extension of the channel whereby lagoon waters are better mixed resulting in improved physico-chemical conditions over this timeframe. Nevertheless, the study of the macrobenthic community did not show any improvement. On the contrary, the species richness and the abundance of the macrofauna have decreased, and some tolerant species such as bivalves (Abra alba and Cerastoderma edule) have increased in abundance. This demonstrates continued impacts on the lagoon ecosystem.