Lagoons play an important socio-economic role and represent a precious natural heritage at risk from fishing pressure and chemical and biological pollution. Our research focused on better understanding the discrimination of fish biodiversity, the detection of non-indigenous species, and the valorization of commercial indigenous species at Mellah lagoon (Algeria). Taxonomic characterization and barcoding for all fish species and Inkscape schematic drawings for the most common species are provided. A total of 20 families and 37 species were recorded. The thermophilic species Coris julis, Thalassoma pavo, and Aphanius fasciatus and tropical species such as Gambusia holbrooki and Parablennius pilicornis were identified. Numerous Mediterranean species of socio-economic importance are highlighted, and detailed information is summarized for the lagoon’s sustainability. This short-term evaluation goes hand in hand with long-term programs documenting the interaction between indigenous and non-indigenous species in the lagoon and will allow the development of a provisional relationship model for future studies. Thermophilic and tropical species patterns in the Mellah lagoon are presented. Taken together, we provide useful data that can guide future investigations and may become a potential management tool for achieving the Sustainable Development Goals and protecting species with large socio-economic roles from potential thermal stress impact.

The removal of heavy metals from industrial waste has become crucial in order to maintain water quality levels that are suitable for environmental and species reproductive health. The biosorption of Zn⁺² and Fe⁺³ ions from aqueous solution was investigated using Ulva lactuca green algal biomass and Corallina officinalis red algal biomass, as well as their activated carbons. The effects of biosorbent dosage, pH, contact time, initial metal concentration, and temperature on biosorption were evaluated. The maximum monolayer capacity of Ulva lactuca and Corallina officinalis dry algal powder and algal activated carbon was reached at pH 5 and 3 for Zn⁺² and Fe⁺³, respectively, while the other factors were similar for both algae, which were: contact time 120 min, adsorbent dose 1 g, temperature 40 °C and initial concentrations of metal ion 50 mg·L⁻¹. The batch experimental data can be modelled using the Langmuir and Freundlich isotherm models. Thermodynamic characteristics revealed that the adsorption process occurs naturally and is endothermic and spontaneous. For the adsorption of Zn⁺² and Fe⁺³ ions, the value of G° was found to be negative, confirming the practicality of the spontaneous adsorption process, which could be helpful for remediation in the era of temperature increases.

Fishes are an important component of human nutrition, mainly acting as source of essential fatty acids in the prevention of cardiovascular disorders. The increase in their consumption has led to a growth of fishes waste; therefore, the disposal and recycling of waste has become a key issue to address, in accordance with circular economy principles. The Moroccan Hypophthalmichthys molitrix and Cyprinus carpio fishes, living in freshwater and marine environments, were collected at mature and immature stages. The fatty acid (FA) profiles of liver and ovary tissues were investigated by GC–MS and compared with edible fillet tissues. The gonadosomatic index, the hypocholesterolemic/hypercholesterolemic ratio, and the atherogenicity and thrombogenicity indexes were measured. Polyunsaturated fatty acids were found to be abundant in the mature ovary and fillet of both species, with a polyunsaturated fatty acids/saturated fatty acids ratio ranging from 0.40 to 1.06 and a monounsaturated fatty acids/polyunsaturated fatty acids ratio between 0.64 and 1.84. Saturated fatty acids were found to be highly abundant in the liver and gonads of both species (range 30–54%), as well as monounsaturated fatty acids (range 35–58%). The results suggested that the exploitation of fish wastes, such as the liver and ovary, may represent a sustainable strategy for the achievement of high value-added molecules with nutraceutical potential.

Several indicators show that the world population is rapidly increasing with prospects of reaching close to 10 billion people in 2050. Optimal production of fish is a tentative goal to ensure human feeding and resources sustainability. The present study was performed on eggs of the silver carp, collected during the breeding season of consecutive years with different environmental temperature profiles at the Deroua Fisheries Station to evaluate the seasonal and inter-seasonal changes of eggs quality in order to promote a predictive marker for optimal production of silver carp. The viability of the obtained eggs was detected using ANOVA followed by the Tukey test to analyze fertilization rate, embryos survival rate, and fry survival rate. Data analysis showed no significant difference in the fertilization and survival rate of the embryos during the two breeding seasons, and therefore these can not be used as an adequate criterion to predict the viability of the fry of silver carp. Although the survival rate of the fry did not change during the first season, it changed significantly during the second when there was an increase in the environmental temperature. This factor could be responsible for the disturbance of the females' oogenesis and consequently the degradation of the eggs' quality. The results showed that the fry survival rate could be used as a parameter to predict the yield of silver carp production rather than the success of fertilization and the survival of embryos. This paper discusses the importance and scope of this approach.

The management of natural surface water resources requires an understanding and knowledge of water quality. The Lake Dayet Er-Roumi (classified as a Site of Biological and Ecological Interest (SIBE)) is the only permanent continental lake of low altitude in Morocco, this international attraction site is subject to various sources of anthropogenic pollution, in addition to the effects of climate change (thermal variability, lack of precipitation, etc.). The objective of this work is to quantify and assess the quality of the waters lake, and its tributaries through Spatio-temporal monitoring of several physicochemical parameters during two seasons (winter and summer) of the year 2019. All the physicochemical analysis (such as temperature, hydrogen potential, electrical conductivity, dissolved oxygen, nitrates, orthophosphates, and chlorides) were carried out at 7 study stations (5 stations at lake level and 2 stations representing the tributaries). Statistical calculation of the data set revealed high concentrations of chlorides in both seasons and orthophosphates during the summer season, with average nitrate concentrations during the winter season. The results obtained show that the pH of the water is basic with a very high electrical conductivity showing a load of water in different minerals. These results greatly exceed the standards of fish water quality and surface water quality. They show that the lake Dayet Er-Roumi is polluted. Strategies to limit the pollution of the lake must be implemented by decision-makers at all levels, in order to avoid several ecological problems (fish mortality for example).

The pike perch Sander lucioperca (L.) is present in numerous Moroccan water bodies. This species has shown functional acclimatization capacity and growth [1]. The current work consists of establishing a qualitative and quantitative study of the diet of males and females caught in the Al-Massira reservoir, by analysis of stomach contents during an annual cycle from October 2018 to September 2019. The stomach contents of 945 specimens were analyzed, ranging in size from 17 to 79 cm. Our results show that the average annual vacuity index is 53.84%, with a maximum value in summer and a minimum in winter. The composition of the general diet has been described as a percentage by number (% Cn), percentage by weight or volume (% Cp), percentage by frequency of occurrence (% F), and percentage by food coefficient (% Q). The food spectrum is composed of different categories of prey, with a dominance of the perch (Cn= 47.08% and 50.18%). This study, coupled with the results of previous studies, suggests that pike perch predation can have a significant impact on the dynamics of perch populations in particular. The occurrence frequency (F) shows that all the prey are accidental during the seasons.