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

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

CoopECC: A Collaborative Cryptographic Mechanism for the Internet of Things

The emergence of IoT applications has risen the security issues of the big data sent by the IoT devices. The design of lightweight cryptographic algorithms becomes a necessity. Moreover, elliptic curve cryptography (ECC) is a promising cryptographic technology that has been used in IoT. However, connected objects are resource-constrained devices, with limited computing power and energy power. Driven by these motivations, we propose and develop a secure cryptographic protocol called CoopECC which leverages the organization of IoT nodes into cluster to distribute the load of cluster head (CH) among its cluster members. This technique proves that it optimizes the resource consumption of the IoT nodes including computation and energy consumption. Performance evaluation, done with TOSSIM simulator, shows that the proposed protocol CoopECC outperforms the original ECC algorithm, in terms of computation time, consumed energy, and the network’s lifespan

Solar Salterns and Pollution: Valorization of Some Endemic Species as Sentinels in Ecotoxicology

Solar salterns and salt marshes are unique ecosystems with special physicochemical features and characteristic biota. Currently, there are very few studies focused on the impacts of pollution on these economic and ecological systems. Unfortunately, diversified pollution (metals, Polycyclic Aromatic Hydrocarbons, etc.) has been detected in these complex ecosystems. These hypersaline environments are under increasing threat due to anthropogenic pressures. Despite this, they represent a valuable source of microbial diversity, with taxa displaying special features in terms of environmental remediation capacities as well as economical species such as Artemia spp. (Branchiopoda) and Dunaliella salina (Chlorophyta). In this review, we discuss the impacts of pollution on these semi-artificial systems. Therefore, we have indicated the sentinel species identified in plankton communities, which can be used in ecotoxicological investigations in solar salterns. In future, researchers should increase their interest in pollution assessment in solar salterns and salt marshes

Abundance and biomass of prokaryotic and eukaryotic microorganisms coupled with environmental factors in an arid multi-pond solar saltern (Sfax, Tunisia)

International audienceThe distribution of abundance and biomass of prokaryotes, flagellates, ciliates and phytoplankton, were studied in five ponds of increasing salinity in the Sfax solar saltern (Tunisia) coupled with environmental factors. The results showed that abundance of eukaryotic microorganisms decreased with increasing salinity of the ponds whereas prokaryotes (heterotrophic bacteria and Archaea) were abundant in the hyper-saline ponds. Phototrophic picoplankton was found in a large range of salinity values (70 and 200‰). Phototrophic non-flagellated nanoplankton which dominated in the first sampled pond was substituted by phototrophic flagellated nanoplankton in the other ponds. Heterotrophic nanoplankton dominated in the crystallizer pond but its quantitative importance declined in the less saline ponds. Diatoms and dinoflagellates were the major contributors to phytoplankton abundance in the first ponds (.90% of total abundance). Ciliated protozoa were found in all the ponds except in the crystallizer in which prokaryotes proliferated. Oligotrichida and Heterotrichida were the most abundant ciliate groups. Overall, species richness decreased with salinity gradient. We propose a simplified diagram of the Sfax saltern's food web showing the dominant role of the microbial loop along the salinity gradient

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