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Fish mass mortality events (FMMEs) represent an escalating ecological crisis, significantly threatening aquatic biodiversity, particularly in North African freshwater ecosystems. Addressing a critical knowledge gap in this region, our study presents the first comprehensive assessment of FMMEs in Moroccan aquatic ecosystems, including freshwater systems and estuaries, based on meticulous monitoring from January 2020 to December 2022. During this three-year period, we documented 18 FMMEs across 16 distinct ecosystems, with a notable increase in frequency observed during the summer and autumn months. Estuaries emerged as critical hotspots for these events, exhibiting the highest frequency of FMMEs and highlighting their vulnerability to climatic and anthropogenic pressures. Our findings indicate a staggering loss of at least 7.8 million fish, with Atherina boyeri, accounted and identified as the most affected species by FMMEs. The families Cyprinidae and Mugilidae experienced the most substantial impacts, including significant biomass losses in Chelon saliens, Chelon labrosus, and Cyprinus carpio. Additionally, endemic species such as Luciobarbus maghrebensis and Luciobarbus rabatensis also faced considerable declines. These events underscore severe ecological disruptions and provide novel insights into species distribution and interactions, including the first recorded presence of Oreochromis niloticus in previously undocumented regions. This research underscores the urgent need for targeted conservation strategies and proactive interventions to mitigate the ecological and socioeconomic ramifications of FMMEs. By addressing these critical issues, we can better protect Moroccan freshwater ecosystems that are at risk of further biodiversity loss., Competing Interests: Declarations. Ethics approval: Not applicable. Consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

This research investigates the effects of environmental interventions on pollution levels along the Anza coast of Morocco from 2010 to 2022 through the analysis of biomarkers in Perna perna. Historically, the Anza area has been highly polluted compared to the nearby Cap Ghir coast. Following the relocation of a cement factory and the establishment of wastewater treatment facilities, notable environmental improvements were noted in Anza. Pollution biomarkers such as acetylcholinesterase (AChE), catalase, glutathione S-transferases (GSTs), and malondialdehyde (MDA) were analyzed to assess these changes. The findings indicated an increase in catalase and AChE levels at Anza, suggesting reduced contamination, while GST activity declined, indicating lower exposure to pollutants. In contrast, Cap Ghir showed an increase in oxidative stress biomarkers, suggesting worsening environmental conditions. The Integrated Biomarker Response (IBR) index demonstrated a significant reduction in pollution levels in Anza, with a corresponding increase at Cap Ghir. Principal Component Analysis (PCA) supported these outcomes, revealing a positive correlation between catalase activity and reduced oxidative stress at Anza, whereas Cap Ghir showed elevated oxidative stress markers linked to variations in temperature and salinity. These results underscore the effectiveness of the interventions in enhancing marine health at Anza and highlight the necessity for protective actions at Cap Ghir. This study emphasizes the importance of biomonitoring in shaping environmental policies for coastal areas of Agadir city., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In Agadir Bay, a study evaluated pollution biomarkers in the mollusk species Patella vulgata. Samples were collected seasonally from September 2021 to September 2022 at two distinct coastal sites within Agadir Bay: Cap Ghir and Anza Beach. Notable variations were observed in biomarkers like malondialdehyde, with a peak at 10.62 nmol/mg P in spring 2022 at Anza Beach. Catalase activity spiked in spring at 69.56 µmol/min/mg P for Cap Ghir and 72.73 µmol/min/mg P for Anza Beach. Acetylcholinesterase showed a decrease at 9.84 nmol/min/mg P in autumn at Anza Beach. Meanwhile, glutathione-S-transferase recorded an increase to 317.96 nmol/min/mg P at Cap Ghir in spring 2022. Using the Integrated Biomarker Response (IBR), these results were visualized, highlighting more stress in mollusks from Anza Beach compared to Cap Ghir. This research provides critical insights into the environmental effects on P. vulgata and potential conservation strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

This work presents preliminary results about abundance, distribution, characteristics, sources, and fate of microplastics (MPs) in the Central Atlantic Ocean (CAO) of Morocco. The investigation was conducted into three subsections, each characterized by different types of human activities and covering rural, village, and urban areas. MPs were detected in 100 % of the sampling sites. The abundances varied from 0.048 to 3.305 items/m 3 , with a mean abundance of 0.987 ± 1.081 items/m 3 . MPs abundance was higher in surface seawater linked to urban areas compared to village and rural areas. The dominant polymer type was polyester (PET-53.8 %) followed by polypropylene (PP-24.36 %), polyamide (PA-7.56 %), polystyrene (PS-6.88 %), polyvinyl chloride (PVC-2.64 %), ethylene vinyl acetate (EVA-2.60 %), polyetherurethane (PUR-1.36 %), and acrylic (AC-0.8 %). Fibers were the most dominant shapes accounting for over 50 %. MPs were mainly smaller than 2 mm in size (71 %) and characterized by colorful aspects. These findings suggested that wastewater treatment plant (WWTP) effluents and anthropogenic activities (industry, tourism, sanitation, and fishing) are the major pollution sources of MPs in the study area. SEM/EDX micrographs showed different weathering degrees and chemical elements adhered to the MPs surface., (Copyright © 2022. Published by Elsevier Ltd.)