Pollution by heavy metals is one of the most serious issues in the world, and the principal sources are manufacturing, fertilizers, mining, pesticides, transport, and wastewater discharge. In this study, the presence of macroelements (Nitrogen (N) and Phosphorus (P)) and heavy metals (Chromium (Cr), Nickel (Ni), Cadmium (Cd), Iron (Fe), Zinc (Zn), Lead (Pb), Cooper (Cu), and Manganese (Mn)) in the green tide caused by the green seaweed Ulva lactuca from Marchica lagoon (NE-Morocco, Mediterranean) was evaluated. The mean values of P and N in the algae were 1773.33 mg·kg ⁻¹ and 44.4 g·kg ⁻¹, respectively. The heavy metals have mean values following this descending sequence: Fe > Mn > Zn > Cu > Ni > Pb > Cr > Cd. This finding has suggested that Ulva has the strongest affinity to Fe and Mn among the metals examined. Mn, Fe, and Pb recorded the highest bioconcentration factors (BCFs), which were 1687, 1656, and 1643, respectively. Regarding their contribution to the Recommended Dietary Allowance (RDA), Fe showed a contribution of 13.58% to the RDA, while that of Mn varied between 4.42 % and 28.42%. The health risk assessment did not indicate any hazard related to the ingestion of Ulva lactuca. Therefore, this study suggests that Ulva lactuca in the Nador lagoon has the potential to bioaccumulate heavy metals and mitigate eutrophication.

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 ecosystems 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 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.

Understanding the temporal and spatial patterns, as well as habitat preferences, of marine communities is crucial for interpreting ecosystem functioning and effectively protecting marine organisms’ resources. In this paper, we investigated the changes in marine communities in the Moroccan Mediterranean (20–620 m depth) over both space and time. Using data from trawl scientific surveys conducted by the National Fisheries Research Institute from 2018 to 2021, we conducted a quantitative analysis to (1) assess the seasonal spatial patterns of bentho‐demersal communities, including both economically important species and those not directly targeted by fisheries, and (2) explore the interactions between these communities and environmental factors to gain deeper insights into the dynamics of communities structure. We selected several environmental characterizations including depth, sea surface temperature, bottom temperature, salinity, chlorophyll‐a, dissolved oxygen, pH, and bottom seabed nature. Depth was the predominant factor responsible for most of the variation observed in both ecological parameters and the composition of bentho‐demersal species. The study largely confirms that bentho‐demersal communities along the Moroccan Mediterranean coast respond to their environment, displaying a structural pattern shaped by an offshore to inshore environmental gradient, and exhibiting low seasonal variations. These results have significant implications for fisheries management, offering crucial insights into the parameters influencing the distribution of bentho‐demersal communities. This is particularly relevant for mixed‐species fisheries, just like those operating in the Moroccan Mediterranean trawl fishery.