Synthesis review of the Gulf of Gabes (eastern Mediterranean Sea, Tunisia): Morphological, climatic, physical oceanographic, biogeochemical and fisheries features

Béjaoui, Béchir; Ismail, Sana Ben; Othmani, Achref; Hamida, Olfa Ben Abdallah-Ben Hadj; Chevalier, Cristèle; Feki-Sahnoun, Wafa; Harzallah, Ali; Hamida, Nader Ben Hadj; Bouaziz, Riadh; Dahech, Salem; Diaz, Frédéric; Tounsi, Khouthir; Sammari, Chérif; Pagano, Marc; Hassen, Malika Bel

doi:10.1016/j.ecss.2019.01.006

Cited by 52 publications

(31 citation statements)

References 98 publications

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“…1). Continental shelf waters are known to be significantly more sensitive to atmospheric conditions (Béjaoui et al, 2019) with wind-induced mixing that quickly homogenizes the water column and salinity reacting instantaneously to evaporation, runoff, or heavy rain (Ben Ismail et al, 2017).…”

Section: Oceanic Conditionsmentioning

confidence: 99%

Impact of a medicane on the oceanic surface layer from a coupled, kilometre-scale simulation

Bouin

Brossier

2020

Ocean Sci.

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Abstract. A kilometre-scale coupled ocean–atmosphere numerical simulation is used to study the impact of the 7 November 2014 medicane on the oceanic upper layer. The processes at play are elucidated through analyses of the tendency terms for temperature and salinity in the oceanic mixed layer. While comparable by its maximum wind speed to a Category 1 tropical cyclone, the medicane results in a substantially weaker cooling. As in weak to moderate tropical cyclones, the dominant contribution to the surface cooling is the surface heat fluxes with secondary effects from the turbulent mixing and lateral advection. Upper-layer salinity decreases due to heavy precipitation that overcompensates the salinizing effect of evaporation and turbulent mixing. The upper-layer evolution is marked by several features believed to be typical of Mediterranean cyclones. First, strong, convective rain occurring at the beginning of the event builds a marked salinity barrier layer. As a consequence, the action of surface forcing is favoured and the turbulent mixing dampened with a net increase in the surface cooling as a result. Second, due to colder surface temperature and weaker stratification, a cyclonic eddy is marked by a weaker cooling opposite to what is usually observed in tropical cyclones. Third, the strong dynamics of the Strait of Sicily enhance the role of the lateral advection in the cooling and warming processes of the mixed layer.

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Section: Oceanic Conditionsmentioning

confidence: 99%

Impact of a medicane on the oceanic surface layer from a coupled, kilometre-scale simulation

Bouin

Brossier

2020

Ocean Sci.

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“…The Bizerte and Kelibia lagoons are two of these coastal lagoons located in north-east Tunisia. Previous ecological studies on these two lagoons have shown that these lagoons differ from each other in their environmental characteristics, particularly in temperature, salinity and currents (Béjaoui et al ., 2008, 2010, 2019; Alves Martins et al ., 2015; Jamila et al ., 2016; Kaouèche et al ., 2017; Zaafrane et al ., 2019). Besides, the Bizerte lagoon is subjected to various anthropogenic pressures that include urbanization, industrial activities, naval and commercial shipping harbours, as well as contamination with chemicals and heavy metals (Barhoumi, 2014).…”

Section: Introductionmentioning

confidence: 99%

Otolith fluctuating asymmetry inBoops boops(Actinopterygii, Sparidae) from two marine stations (Bizerte and Kelibia) in Tunisian waters

et al. 2020

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For the first time, saccular otolith shape and size were analysed in 254 samples of the bogue Boops boops collected from the marine stations of Bizerte and Kelibia situated in north-east Tunisia. The objectives were (1) to examine the inter- and intra-population variation in the otolith shape and size, including length (Lo), width (Wo) and area (Ao) measurements, and (2) to assess the relationship between otolith mass asymmetry (OMA) and total fish length (TL). In addition, the impact of pollution present in these two stations on the shape and size of the otolith in relation to the TL was discussed. Analyses of the otolith shape and biometric data showed a statistically significant asymmetry in the otolith shape (P < 0.0001) between the right and left sides within the population of Bizerte, as well as between the otoliths from the same right-right and left-left sides between the populations of Bizerte and Kelibia. Similarly, a significant Wo asymmetry (P < 0.05) was recorded within the population of Kelibia. Conversely, a significant symmetry was detected in Lo and Ao (P > 0.05) between the right and left sides within the populations of Bizerte and Kelibia. Moreover, the level of asymmetry of Ao was higher than that of Lo and Wo in both populations. Nevertheless, Student's t-test showed no statistically significant differences (P > 0.05) for Lo, Wo and Ao in relation to the means of TL between the three groups of the populations of Bizerte and Kelibia, although significant differences (P < 0.05) were found by using box plots. Furthermore, no statistically significant relationship (P > 0.05) was detected between OMA and TL within and between the populations of Bizerte and Kelibia. The possible cause of fluctuating asymmetry (FA) in the otolith shape and size both within and/or between populations of the two stations has been discussed in relation to the instability of development induced by environmental stress associated with the variation in water temperature, salinity, depth, feeding conditions and pollutants present in these stations.

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“…Marine planktonic Archaea are currently classified into four main groups belonging the phyla Thaumarchaeota (formerly Marine Group I archaea) and Euryarchaeota (Marine Groups II, III, and IV; Santoro et al, 2019). Although many studies have evaluated the spatiotemporal diversity of prokaryotes in several marine regions throughout the world, including the Mediterranean Sea (Ghiglione et al, 2005;Feingersch et al, 2010;Galand et al, 2010;Techtmann et al, 2015), their responses to environmental changes remain largely unknown in many specific coastal areas, especially along the southern coasts of the Mediterranean Sea, impacted by anthropogenic activities, climatic changes, and a complex water circulation pattern (Bel Hassen et al, 2009a;Coll et al, 2010;Zouch et al, 2018;Béjaoui et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…This eastern basin is the most oligotrophic area of the Mediterranean Sea, and their phytoplanktonic communities were mainly composed of ultraphytoplankton (<10 µm), which play an important role in the primary production (Bel Hassen et al, 2009b;Estrada and Vaqué, 2014;Khammeri et al, 2020). In the eastern Mediterranean basin, the Gulf of Gabès is one of the most productive Mediterranean area (Ayata et al, 2018), due to the favorable climatic conditions and the high nutrient availability, contrasting with the oligotrophic waters of the eastern basin (Béjaoui et al, 2019). Changes in picoeukaryotic assemblages, phytoplankton abundance and ultraphytoplankton composition have been largely studied in the shallow waters of the Gulf of Gabès (Bel Hassen et al, 2009a,b;Rekik et al, 2014;Hamdi et al, 2015;Bellaaj-Zouari et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Prokaryotic Diversity and Distribution Along Physical and Nutrient Gradients in the Tunisian Coastal Waters (South Mediterranean Sea)

et al. 2020

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Prokaryotes play an important role in biogeochemical cycling in marine ecosystems, but little is known about their diversity and composition, and how they may contribute to the ecological functioning of coastal areas in the South Mediterranean Sea. This study investigated bacterial and archaeal community diversity in seawater samples along the Tunisian coast subject to important physicochemical disturbances. The 16S amplicon sequencing survey revealed higher prokaryotic diversity in the northern Tunisian bays than in southeastern waters (Gulf of Gabès). The major taxonomic groups identified in all samples were Alphaproteobacteria (40.9%), Gammaproteobacteria (18.7%), Marine Group II Euryarchaeota (11.3%), and Cyanobacteria (10.9%). Among them, the relative abundance of Alteromonadales, Prochlorococcus, and some clades of Pelagibacterales (SAR11) significantly differed between the northern and the southern bays, whereas no difference was observed across coastal waters in the archaeal Candidatus Poseidoniales (MGII), Synechococcus, and Pelagibacteraceae (SAR11 clade Ia), for which no relationship was observed with the environmental variables. Both Pseudoalteromonas and Alteromonas levels increased with the increasing salinity, density and nutrients (NH4+ and/or PO43–) gradients detected toward the southern waters, while the SAR11 clades Ib and IV and Prochlorococcus, decreased in the shallow, salty and nutrient-rich coastal waters of the Gulf of Gabès. Rhodobacteraceae was positively correlated with Synechococcus and chlorophyll levels, suggesting a relationship with phytoplankton biomass. The present study provides the first insights into planktonic prokaryotic community composition in the South Mediterranean Sea through the analysis of Tunisian seawaters, which may support further investigations on the role of bacterioplankton in the biogeochemistry of these ecosystems.

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Synthesis review of the Gulf of Gabes (eastern Mediterranean Sea, Tunisia): Morphological, climatic, physical oceanographic, biogeochemical and fisheries features

Cited by 52 publications

References 98 publications

Impact of a medicane on the oceanic surface layer from a coupled, kilometre-scale simulation

Impact of a medicane on the oceanic surface layer from a coupled, kilometre-scale simulation

Otolith fluctuating asymmetry inBoops boops(Actinopterygii, Sparidae) from two marine stations (Bizerte and Kelibia) in Tunisian waters

Prokaryotic Diversity and Distribution Along Physical and Nutrient Gradients in the Tunisian Coastal Waters (South Mediterranean Sea)

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