Trace metals and macrominerals in common seaweeds in the Marchica (a restored lagoon, Mediterranean Sea): Nutritional value and health risk assessment.

This study investigated the contents of macrominerals (Na, K, Ca, Mg and P) and essential trace metals (Fe, Mn, Cu, Zn and Se) in four species of seaweeds (Gracilaria sp., Alsidium corallinum, Caulerpa prolifera, and Chaetomorpha sp.) from Marchica Lagoon. The contents of macrominerals with mean values (% dw) can be sequenced in this descending order, [Ca > Mg > Na > K > P] for Caulerpa prolifera, and the decreasing sequence [K > Ca > Mg > P > Na] for Chaetomorpha sp. In red seaweeds, Gracilaria sp. and Alsidiumcorallinum followed these orders: [K > Ca > Na > Mg > P] and [K > Na > Ca > Mg > P] respectively. The essential trace metals mean values (mg kg-1) followed the decreasing order [Fe > Mn > Zn > Cu > Se] for Alsidiumcorallinum, Chaetomorpha sp. and Gracilaria sp., and the following order [Fe > Mn > Zn > Se > Cu] for Caulerpa prolifera. Based on the calculated recommended dietary allowance (RDA), targeted hazard quotient (THQ) and the hazard index (HI), the studied seaweeds did not pose any health risk for human consumption.

Evaluation of the water quality and the eutrophication risk in Ramsar site on Moroccan northern Mediterranean (Marchica lagoon): A multivariate statistical approach.

This study aimed to assess the extent of eutrophication in the Marchica lagoon, using the trophic index (TRIX), trophic status index (TSI) and Redfield ratio (N/P). Seawater samples were collected monthly from March 2018 to February 2019 from ten locations in the lagoon. The TRIX index ranged from 1.25 to 8.87, indicating oligotrophic to eutrophic conditions. TSI values ranged from 28.4 to 65.1, indicating ultraoligotrophic to supereutrophic seawater. The Redfield ratio consistently showed N/P values below 16, designating phosphorus as the limiting factor for algal growth. Principal component analysis (PCA) and cluster analysis (CA) revealed distinct coastal water masses based on seasons and sampling regions. Given these findings, urgent conservation and management measures are recommended to address the eutrophication issues threatening the delicate balance of the Marchica lagoon.

Trophic Interactions of European Hake Merluccius merluccius (Linnaeus, 1758) in Benthic Communities off the Moroccan Mediterranean Coastline: Seasonal and Ontogenetic Shifts.

The European hake, Merluccius merluccius (Linnaeus, 1758), is one of the most important resources for Mediterranean fisheries. Due to its pivotal role in energy transfer from lower to higher trophic levels, this species is a crucial component of the ecosystem's functioning. The ecological role of Merluccius merluccius, off the Moroccan Mediterranean Sea (southern Alboran Sea), was investigated, exploring seasonal and ontogenetic shifts, geographical variations in prey composition, and feeding strategy. Between November 2020 and July 2022, a total of 402 hake specimens were collected by oceanographic bottom trawl surveys (MEDITS) that were carried out during warm and cold seasons to assess their diet and feeding habits. The sample was analyzed according to fish sizes and seasons, and qualitative/quantitative feeding indices were calculated. The trophic spectrum of Merluccius merluccius included 24 prey items in total, mainly belonging to Osteichthyes (12), Crustacea (10), Cephalopoda (1), and Polychaeta (1), suggesting a generalist behavior of this predator as in numerous regions of the Mediterranean Sea, with several species that occasionally occurs in its diet. In the Moroccan Mediterranean Sea, Osteichthyes proved to be the most important prey item (%IRI = 78.56) among the different zoological groups, followed by Crustacea (%IRI = 16.22). The other food items were occasionally and randomly consumed, and cannibalism was low (0.8%). Hierarchical cluster analysis and nonmetric multidimensional scaling (nMDS) showed different feeding habits of two main groups separated at 60% similarity: small specimens <10 cm TL, primarily feed on zooplanktonic prey, while medium and large specimens hold a diet based on Osteichthyes with crustaceans. Furthermore, a significant positive relationship between hake and fish prey size was confirmed. Seasonally, mesopelagic Osteichthyes were the main food prey in the summer season, while pelagic species were predominant during the autumn. SIMPER analysis revealed that the prey items contributing the most to the differences between seasons and length classes were Engraulis encrasicolus, Micromesistius poutassou, Boops boops, Macroramphosus scolopax, gobids, Gadiculus argenteus, and most of Crustacea. The diet does not appear to be influenced by sex (>0.05). A trophic level (TROPH) of 4.1 was calculated, indicating that the species is a top predator (quaternary consumers). The TROPH values ranged between 2.58 and 4.38 from juveniles to adults, increasing asymptotically with the size of specimens. In contrast to what has previously been found in other Mediterranean regions, where ichthyophagous hake feed mostly on pelagic Osteichthyes, such as Engraulis encrasicolus, Sardina pilchardus, and Micromesistius poutassou, the study points up the vital role played by Atlantic horse mackerel Trachurus trachurus for hake diet in the Moroccan Mediterranean Sea. Information on the feeding ecology of fish species as provided in this study is essential to improve ecosystem conservation in accordance with multispecies approach to fishery management, leading to a better understanding of the role of hake in the Moroccan Mediterranean Sea demersal communities.

The chemical characterization and its relationship with heavy metals contamination in surface sediment of Marchica Mediterranean Lagoon (North of Morocco).

The sediments were studied according to the granulometric characteristics, the geochemical analyses of the sediments (organic matter (OM), carbonate, and pH), the analyses of heavy metals (HM) characteristics, and their contamination status in the ecological system and the mineralogical analysis of the sediments at 8 sites spread over the Marchica lagoon (NE-Morocco). Our results showed that the opening of the new wide and deep pass affected the spatial distributions of the metals, which were closely related to fine fraction and sediment OM concentration. In the north and southeast lagoon zones presented low concentrations of the HM, fine particles (clay), OM, whereas the south and the center of the lagoon were heavily loaded with HM and OM, corresponding to the trapping zones by fine particles. The results of mineralogy analyses have revealed the predominance of non-clay minerals such as quartz and calcite, and for the clay fractions of sediments showed that they are formed of illite, kaolinite, smectite, and chlorite in highly variable proportions; illite was the most dominant clay in the north-western Marchica lagoon sediments. Therefore, the HMs are fixed by clay colloids having a high cation exchange capacity with smectite-chlorite-kaolinite assembly.

Seasonal variations of heavy metals content in mussels (Mytilus galloprovincialis) from Cala Iris offshore (Northern Morocco).

Heavy metal concentrations of Cd, Cr, Cu, Fe, Ni, Zn, Co, and Pb were investigated in soft tissues of Mytilus galloprovincialis coming from an aquaculture farm in Cala Iris sea of AlHoceima. Mytilus galloprovincialis were collected monthly during the period January to December 2016. The seasonal variations were affected significantly the concentrations of metals (Cd, Fe and Cr) in M. galloprovincialis. The highest heavy metal concentrations were recorded in winter (0.89 mg/kg, 673.2 and 3.330 mg/kg; for Cd, Fe and Cr, respectively) and the lowest values were founded in summer for Cd (0.646 mg/kg), and in autumn for Fe (340.1 mg/kg) and Cr (1.959 mg/kg). A significant effect of seasons on metal concentrations can be attributed to a number of biological and environmental inter-related factors. Data from this study may provide information on the use of M. galloprovincialis as a bioindicator for heavy metals pollution in the Cala Iris Sea.