Evaluation of the Water Quality and the Eutrophication Risk in Mediterranean Sea Area: A Case Study of the Gulf of Gabès

The Gulf of Gabès, located in southern Tunisia, is a distinct and ecologically significant area in the Mediterranean Sea. Unfortunately, this dynamic marine ecosystem is experiencing cultural eutrophication, a process where water enrichment with nutrients like phosphorus and nitrogen salts leads to excessive algae growth, disrupting the ecological equilibrium and degrading water quality. In the Gulf of Gabès, key sources of nutrient pollution include industrial discharges, urbanization and agriculture. Eutrophication’s effects here include harmful algal blooms, oxygen depletion, and declining water quality, upsetting the marine ecosystem’s balance and impacting both fish and aquatic life. Nutrient enrichment interacts with trace metal pollution, overfishing and climate change. Future research must acknowledge and consider the complex interactions among these variables. Efforts in the Gulf of Gabès to address eutrophication involve tighter industrial regulations, enhanced agriculture and improved wastewater management, all crucial for preserving the marine environment’s integrity and ensuring sustainability for the future

Antioxidant Properties of Metabolites from New Extremophiles Microalgal Strain (Southern, Tunisia)

With the demand for bioproducts that can provide benefits for biotechnology sectors like pharmaceuticals, nutraceuticals, and cosmeceuticals, the exploration of microalgal products has turned toward extremophiles. This chapter is intended to provide an insight to most important molecules from halotolerant species, the cyanobacteria Phormidium versicolor NCC-466 and Dunaliella sp. CTM20028 isolated from Sfax Solar Saltern (Sfax) and Chott El-Djerid (Tozeur), Tunisia. These microalgae have been cultured in standard medium with a salinity of 80 PSU. The in vitro antioxidant activities demonstrated that extremolyte from Dunaliella and Phormidium as, phycocaynin, lipids, and polyphenol compound presents an important antioxidant potential

A biclustering algorithm based on a Bicluster Enumeration Tree: application to DNA microarray data

<p>Abstract</p> <p>Background</p> <p>In a number of domains, like in DNA microarray data analysis, we need to cluster simultaneously rows (genes) and columns (conditions) of a data matrix to identify groups of rows coherent with groups of columns. This kind of clustering is called <it>biclustering</it>. Biclustering algorithms are extensively used in DNA microarray data analysis. More effective biclustering algorithms are highly desirable and needed.</p> <p>Methods</p> <p>We introduce <it>BiMine</it>, a new enumeration algorithm for biclustering of DNA microarray data. The proposed algorithm is based on three original features. First, <it>BiMine </it>relies on a new evaluation function called <it>Average Spearman's rho </it>(ASR). Second, <it>BiMine </it>uses a new tree structure, called <it>Bicluster Enumeration Tree </it>(BET), to represent the different biclusters discovered during the enumeration process. Third, to avoid the combinatorial explosion of the search tree, <it>BiMine </it>introduces a parametric rule that allows the enumeration process to cut tree branches that cannot lead to good biclusters.</p> <p>Results</p> <p>The performance of the proposed algorithm is assessed using both synthetic and real DNA microarray data. The experimental results show that <it>BiMine </it>competes well with several other biclustering methods. Moreover, we test the biological significance using a gene annotation web-tool to show that our proposed method is able to produce biologically relevant biclusters. The software is available upon request from the authors to academic users.</p

Cyclopoida and Harpacticoida (crustacea: Copepoda) of the Gulf of Gabès: a review

This study presents a faunal list of Cyclopoida and Harpacticoida in the Gulf of Gabès waters. A total of 30 Cyclopoida and 11 Harpcticoida species belonging to 5 and 8 families, respectively, were reported in this study area. Corycaeidae is the most diversified family with 10 species including the invasive Atlantic species, Ditrichocorycaeus amazonicus. The Oithonidae (mainly Oithona nana) were dominant in the coastal waters, whereas they declined in the offshore area, most likely due to the influence of the Atlantic Tunisian Current

Marine Calanoida (crustacea: Copepoda) of the Gulf of Gabes: a review

This study presents a faunal list of Copepoda Calanoida in the Gulf of Gabès (Tunisia). A total of 52 species belonging to15 families were reported in this study area, including 11 species belonging to family Acartiidae. Due to the geographical position of Gulf of Gabès in the middle of the Mediterranean Sea, the Tunisian Calanoida fauna in this area can be considered as a mixture of non-indigenous species mainly from Atlantic, cosmopolitan species, and endemic species

CORRESPONDENCE OF THE SEASONAL PATTERNS OF THE BRINE SHRIMP, ARTEMIA SALINA (LEACH, 1819) (ANOSTRACA) WITH SEVERAL ENVIRONMENTAL FACTORS IN AN ARID SOLAR SALTERN (SFAX, SOUTHERN TUNISIA)

International audienceWe investigated the correspondence of the seasonal patterns of Artemia salina with several environmental factors along a natural salinity gradient in four ponds (M1, M2, M3, and B1) located in the arid solar saltern of Sfax (southern Tunisia). The shape of the frontal knobs of males showed the dominance of the autochthonous species, A. salina. Artemia abundance and fecundity were assessed. Biometrics of A. salina stages were studied by comparing cyst size and body length. A. salina abundance displayed a clear seasonal and spatial variation. Abundance of live Artemia ranged between 0.25 × 103 and 1414 × 103 ind m−3. The highest numbers were recorded in pond M3, as nauplii (771.8×103 ind m−3 corresponding to 31.8 g m−3). This resulted from low male and female numbers (34 and 17×103 ind m−3, respectively). Artemia cysts were predominant (92.96% of total Artemia), and grouped in small (216 μm) and large (243 μm) sized cysts, which correlated negatively with temperature (r = −0.4, N = 294, p < 0.01) and salinity (r = −0.39, N = 294, p < 0.01), and positively with female fecundity (r = 0.6, p < 0.05). The large (270 μm) and small (216 μm) cysts suggested the presence of also the species A. parthenogenetica and A. franciscana in the saltern, respectively. Fecundity showed a summer-autumn distribution that correlated significantly (−0.6 and −0.9, N = 35, p < 0.01) with both temperature and salinity. A. salina performed best in M2 (more than 80 cysts per brood), at about 200 g l−1 and 26.8◦C, with gravid females representing 20%. A. salina from the Sfax solar saltern was unable to withstand extreme temperatures (35◦C), but tolerated extreme salinity (330 g l−1). Abundance, biometrics, and reproductive descriptors of A. salina appeared to be governed chiefly by temperature and salinity, the physical structure of the saltern, and food availability, such as the unicellular green alga, Dunaliella salina. Nauplii (mean length: 401 μm) from small-sized cysts encountered in the saltern might be a valuable food source for hatcheries of some small-mouthed marine fish

Evolutionary biclustering algorithms: an experimental study on microarray data

International audienc

Seasonal dynamics of zooplankton community in four Mediterranean reservoirs in humid area (Beni Mtir: north of Tunisia) and semi arid area (Lakhmes, Nabhana and Sidi Saâd: center of Tunisia)

International audienceThe zooplankton community was studied in four Mediterranean reservoirs to assess the relative importance of environmental factors as determinants of zooplankton dynamic in the four seasons. The water temperature and hydrology variations affect the distribution of zooplankton. A positive correlation was established between the total zooplankton and the water temperature (r=0.9, n=9, p<0.05). Fourteen zooplankton species were identified. Seasonal changes in the density (ANOVA, F=3.7, d.f=36, p<0.01) and the biomass of total zooplankton (ANOVA, F=4.4, d.f=36, p<0.001) were observed. Our results suggest that planktivorous fish may not modify the zooplankton dynamics in Beni Mtir reservoir (oligotrophic). On the contrary, in Sidi Saâd reservoir (mesotrophic), fish predation has major effects on seasonal zooplankton dynamics