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

Abstract

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 2004From -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.

What role do environmental and anthropogenic factors play in the variability of benthic macrofauna in the northern lagoon of Tunis?

“…In general, Mediterranean lagoons are often dominated by one or two trophic groups, as the lagoon of Bizerte dominated widely by carnivores (Afli et al 2008a), the southern lagoon of Tunis by micrograzers, the lagoon of Ghar El-Melh by selective deposit feeders (Afli et al 2009c) and the lagoon of Smir by detritus feeders (Chaouti and Bayed 2011). The trophic organization in the northern lagoon of Tunis in autumn is comparable to that in the lagoon of Boughrara which seems to be more balanced, with total absence of the NSDF (Khedhri et al 2016c). This should be related to the sedimentary dynamic that allows organic matter to be inserted in-depth where the trophic group feeds (Afli et al 2008a).…”

“…In Tunisian lagoons, studies carried out on benthic macro-invertebrates are generally few; among them Ben Souissi (2002) had studied the southern lagoon of Tunis, Chakroun (2004) and Afli et al (2009bAfli et al ( , 2009c both the southern lagoon of Tunis and the lagoon of Ghar El-Melh, Khedhri et al (2016aKhedhri et al ( , 2016bKhedhri et al ( , 2016c) the lagoon of Boughrara, Afli et al (2009a) and Zaabar et al (2014) the lagoon of Bizerte, etc.…”

“…Benthic invertebrates have been largely used as bio-indicators for aquatic monitoring because they respond rapidly to anthropogenic and natural stressors (Pearson andRosenberg 1978, Munari andMistri 2012). Furthermore, they have relatively long life spans, meaning they are unable to escape disadvantageous conditions and allowing their use in evaluation of accidental and chronic variations (Dauvin1993, Reiss and Kroncke 2005, Khedhri et al 2015, 2016c. Studies carried out on benthic macrofauna in the study site are generally very few (Afli et al 2008a), and after the restoration measures (Chouari 2015), the benthic community was not yet studied except for the works undertaken by Diawara et al (2008) and Tlig-Zouari and Maamouri-Mokhtar (2008).…”

Polychaete diversity in Tunisian waters as of 2021: an update with special emphasis on Non-Indigenous species

“…Euclymene droebachiensis (Sars, 1872), originating from the North Atlantic, was reported recently in Boughrara Lagoon (Tunisia) (Khedhri et al, 2016a(Khedhri et al, , b, 2017a. This represents a single non-figured report of its presence in the Mediterranean Sea.…”

“…A new species was described from this same sector of the Tunisian coast and a new species was reported for the Mediterranean Sea (Chaibi et al, 2019 and2021, respectively). Other taxonomic and especially ecological studies have been conducted over the last decade in the Gulf of Gabès (Pérez-Domingo et al, 2008;Aloui-Bejaoui & Afli, 2012;Khedhri et al, 2014Khedhri et al, , 2016aKhedhri et al, , b, 2017aMosbahi et al, 2015aMosbahi et al, , b, 2016Mosbahi et al, , 2017Boudaya et al, 2019); these studies have led to the recording of several new polychaete species compared to the inventory of Ayari et al (2009).…”