Diatom Diversity in the Surface Waters of Oued Beht

Diatom Diversity in the Surface Waters of Oued Beht | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Diatom Diversity in the Surface Waters of Oued Beht Youssef Ouballouk, Abdelkader Chahlaoui, Chouaib Amahzoune, Abdelilah Rahou, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6264926/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Diatoms, known for their rapid response to environmental changes, are widely recognized as reliable bioindicators of water quality. Despite their ecological significance, studies on diatom flora in North Africa, particularly in Morocco, remain scarce. This study evaluates the water quality of Oued Beht in northwestern Morocco by integrating physico-chemical analyses with diatom community assessments. Sampling conducted in March 2024 at a representative site revealed elevated pH (9.63), high conductivity (9690 µS/cm), and increased salinity (5.3 mg/L), indicative of significant anthropogenic pressures from domestic, agricultural, and industrial discharges. In contrast, diatom community composition, dominated by pollution-tolerant taxa such as Navicula radiosa (represented by 15 taxa), yielded a diatom biological index (IBD) of 15.76, suggesting relatively good historical water quality. This apparent discrepancy underscores the resilience and ecological memory of diatom communities, which may reflect past conditions even as current physico-chemical parameters indicate moderate environmental degradation. These findings highlight the importance of adopting a holistic approach to monitoring aquatic ecosystem health in Morocco, combining biological and physico-chemical indicators to better understand and manage anthropogenic impacts. Oued Beht water physico-chemical diatom biological index Figures Figure 1 Figure 2 INTRODUCTION Water is a fundamental component of life and a critical resource for all ecosystems. Protecting water quality is essential for sustaining biodiversity, human health, and ecosystem services. Rivers, as dynamic systems, play a vital role in recharging groundwater, supporting biodiversity, facilitating organic matter cycling, and maintaining ecological balance (Dynesius and Nilsson 1994 ; Graça et al. 2002 ). However, increasing anthropogenic activities have led to widespread pollution, causing significant physical and chemical alterations that degrade water quality (Taffouo et al. 2017 ) and disrupt the distribution and abundance of aquatic organisms. In Morocco, water resources face multiple threats, including a semi-arid to arid climate, recurrent droughts, and high-water consumption (Bouaicha and Benabdelfadel 2010 ). These challenges are exacerbated by pollution from domestic, agricultural, and industrial discharges (Chahlaoui 1996 ). As a result, assessing water quality has become a pressing concern (Ongley 2001 ), with pollution risks influenced by the physical, chemical, and biological characteristics of contaminants (Jonnalagadda and Mhere 2001 ). Numerous studies have documented the alarming degradation of continental ecosystems in the region (Abdallaoui et al. 1998 ), underscoring the need for comprehensive monitoring and management strategies. This study focuses on Oued Beht, a 4,500 km² watershed in northwestern Morocco within the Sebou basin. The river is bordered by the Gharb plain, Meknes plateau, Oum-Er-Rbia basin, Bouregreg basin, and the Middle Atlas (Abdallaoui et al. 1998 ). Oued Beht is subject to significant anthropogenic pressures, including the influence of the Kensra dam, domestic wastewater discharges, agricultural runoff, and hydrocarbon pollution. These factors contribute to elevated organic and chemical pollution levels, disrupting the aquatic ecosystem and threatening species distribution, groundwater quality, and overall ecosystem health (Lamhasni et al. 2017). Diatoms, a key component of aquatic ecosystems, are widely recognized as effective bioindicators of water quality due to their sensitivity to environmental changes and their ability to integrate variations in physicochemical properties. They are particularly useful for assessing organic pollution and eutrophication (Lavoie et al. 2008 ). In this study, we employ diatom-based indices to evaluate the water quality of Oued Beht, providing insights into both current conditions and historical trends. By combining physicochemical analyses with diatom community assessments, we aim to offer a holistic understanding of the river’s ecological status and inform sustainable management practices. MATERIALS AND METHODS Study Area The Oued Beht watershed is located upstream of the El Kansra dam, approximately 85 km from Rabat, traversing the Middle Atlas of Morocco. The main watercourse, Oued Beht, is a tributary of the Sebou River (Daide et al. 2022 ). Stretching over 110 km, it originates near Azrou as a result of the confluence between the Oued Tigrigra and the Oued Amghass. The selection of the station is based on three main criteria: the water flow rate of the Oued, the direction of flow, and finally the station’s accessibility. We conducted our sampling campaign in Oued Beht in March 2024 at the station whose location is shown in Fig. 1. Figure 1. Study Area Station (Daide et al. 2022 ) Physicochemical measurements Physicochemical analyses were conducted following the standardized techniques outlined by Rodier et al. ( 2009 ). A total of 13 parameters were assessed, with some measured directly in the field and others analyzed in the laboratory. In situ measurements were conducted using calibrated portable instruments, while laboratory analyses were performed within 24 hours of sampling, following standardized methods described by Rodier et al. ( 2009 ). Details of the methods, instruments, and units are provided in (Table 1 ). Table 1 Physicochemical parameters measured in the field and analyzed in the laboratory, methods, and instruments used. Parameter Measurement Method Unit In-Situ Measurements Temperature Thermometer °C Turbidity Turbidimeter (PCE-PHD 1 model) FTU Dissolved Oxygen DO meter (PCE-PHD 1 model) mg/l Conductivity Conductivity meter (PCE-PHD 1 model) µS/cm (20°C) Salinity Salt meter (PCE-PHD 1 model) mg/L pH pH meter 1–14 Laboratory Analyses Chlorides Mohr Method mg/L Sulfates Nephelometry – sulfates are precipitated in a hydrochloric Environment as barium sulfate mg/L Calcium Molecular Absorption Spectrometry mg/L Ortho Phosphates Molecular Absorption Spectrometry mg/L Nitrates Sodium Salicylate Method mg/L BOD₅ BOD EVO Sensor System 6 mg/L Nitrites Molecular Absorption Spectrometry mg/L Diatoms sampling Samples were collected by scrubbing a 100 cm² area of rock surface, and the resulting material was transferred into 30 ml bottles containing a 4% formaldehyde preservative solution for transport to the laboratory. To remove organic matter and carbonates, samples were treated with 25–30 ml of 30% hydrogen peroxide (H2O2) at 100°C for 1.5 hours, followed by 10 ml of hydrochloric acid (HCl) at 120°C for 2 hours (Van der Werff 1995 ). Oxidation byproducts were eliminated through repeated rinsing and settling with distilled water. Diatom suspensions were then prepared on coverslips and mounted on slides using Zrax (MicrAP, Pennsylvania). Light microscopy (LM) images were obtained using a NIKON Eclipse Ci microscope equipped with a Nikon DS-Fi1 camera. Diatom identification was conducted using taxonomic references, including works by Germain ( 1981 ), Lange-Bertalot & Krammer ( 1989 ), Lange-Bertalot ( 2001 ), Levkov et al. ( 2010 ), Cantonati et al. ( 2011 ), Bey & Ector ( 2013 ), and Ács et al. ( 2016 ). The Diatom Biological Index (IBD) is calculated based on the identification and quantification of diatom species present in a sample. Species abundance is determined by counting a minimum of 300 valves, as outlined in the AFNOR NF T90-354 (2007) standard. This index is fixed based on knowledge of the ecology of each species and its probability of occurrence in different water quality classes. The abundance of each species in the sample is considered to build a representative profile of the diatom community, which is then converted into another IBD score ranging from 1 to 20. This score reflects the level of ecosystem pollution, particularly by nitrogen and phosphorus nutrients, as well as organic matter (AFNOR NF T90-354 2007) (Table 3 ). Table 3 IBD values, corresponding classes, and ecological status IBD Value 17 to 20 13 to 17 9 to 13 5 to 9 1 to 5 Class A B C D E Ecological State Very good state Good state Moderate state Poor state Very poor state RESULTS AND DISCUSSION Physico-chemical parameters The recorded levels of the studied physico-chemical parameters are illustrated in Table 4 . The measured water temperature is 16.6°C, a critical factor for aquatic organisms since it influences both biochemical and biological processes, and sudden changes can disrupt ecosystems; anthropogenic factors such as wastewater discharge, agricultural drainage, and industrial effluents further impact temperature by affecting oxygenation, solubility, and metabolism, which in turn influence diatom development (Bélange et al. 2005; Ben Moussa et al. 2012 ). The pH of 9.63 exceeds Moroccan standards (6.5–8.5) (Ministry of Environment of Morocco 2002 ), indicating high alkalinity likely due to human activities (El Guamri et al. 2007; Neal et al. 2000 ), while conductivity is 9690 µS/cm at 20°C, far above the Moroccan standard (1300–2700 µS/cm), suggesting a high dissolved ion concentration from both natural and anthropogenic sources (Dib, 2009 ). Turbidity is 42.34 NTU, which, although within Moroccan limits (5–50 NTU) (Ministry of Environment of Morocco 2002 ), remains high enough to indicate possible pollution (Ouarrak 2022 ); salinity is 5.3 g/L, exceeding the 2 g/L standard and reflecting influences from geological factors and human activities (WHO 1986, Rodier et al. 2009 ). Dissolved oxygen measures 8 mg/L, surpassing the surface water standard of 5 mg/L and indicating non-polluted conditions (Hébert and Légaré 2000 ), while sulfates at 296 mg/L slightly exceed the 200– 250 mg/L standard, likely resulting from gypsum dissolution and soil leaching, as well as the influence of domestic wastewater (Rodier et al. 2009 ). Nitrates are at 1.52 mg/L, well below the 25–50 mg/L limit and originating from organic matter and fertilizers, indicating some pollution (Derwich et al. 2010 ; C.E.P.A 1997 ), whereas nitrites at 0.778 mg/L exceed the 0.1 mg/L standard, suggesting incomplete ammonium oxidation or nitrate reduction and serving as a sign of organic pollution (Sacchi and Testard 1971 ). The BOD5 is 6 mg/L, within the 5–10 mg/L standard, reflecting oxygen consumption by microorganisms due to soil leaching (Ben Moussa et al. 2012 ), and orthophosphates are measured at 0.633 mg/L, surpassing the < 0.5 mg/L threshold for preventing eutrophication, mainly due to inputs from agriculture, household waste, and fertilizers (Hammami et al. 2005). Chlorides are recorded at 731 mg/L, close to the upper Moroccan limit of 300–750 mg/L, with peaks in inhabited areas (Rodier et al. 2009 ), and calcium is found at 112 mg/L, indicating a significant presence influenced by both geology and human activities (Rodier et al. 2009 ). Table 4 Results of Physico-Chemical Parameters Parameter Value Air and Water Temperature 16.6°C Dissolved Oxygen (DO) 8 mg/L pH 9.63 Conductivity 9690 µS/cm Salinity 5.3 mg/L Turbidity 42.34 NTU Chlorides 0.778 mg/L Sulfates 296 mg/L Ortho Phosphates 0.633 mg/L Nitrates 1.52 mg/L BOD₅ 6 mg/L Calcium 112 mg/L Nitrites 0.778 mg/L Composition of diatom communities In terms of diatoms, we identified a total of 15 taxa belonging to 10 genera (Table 5 ; Fig. 2 ). This demonstrates a great diversity of diatom flora. Such diversity reflects an ability to adapt to a wide range of environmental conditions, including high levels of pollution. Table 5 Diatom Taxa of Oued Beht Taxon Abundance (‰) Navicula radiosa Kützing, 1844 327.92 Stauroneis phoenicenteron (Nitzsch) Ehrenberg, 1843 36.93 Navicula gregaria Donkin, 1861 51.70 Surirella ovalis (Kützing) Kützing, 1844 26.59 Navicula molestiformis (Hustedt) Hustedt, 1956 106.35 Entomoneis paludosa (Brun) Cleve, 1894 73.86 Achnanthes minutissima (Kützing) Cleve, 1894 93.06 Pinnularia viridis (Kützing) Cleve, 1894 14.77 Cymbella affinis (Kützing) Kützing, 1844 17.73 Nitzschia palea (Kützing) W. Smith, 187 36.93 Nitzschia dissipata Hustedt, 1956 109.31 Cyclotella meneghiniana (Kützing) Hustedt, 1930 22.16 Navicula viridula Kützing, 1844 75.33 Amphora veneta (Kützing) Kützing, 1844 7.39 The results show that the diatom flora is dominated (more than 71% of the 677 individuals identified in each sample) by four genera: Navicula, Entomoneis, Achnanthe , and Nitzschia . them, the most frequent species are: Navicula radiosa, Navicula gregaria, Navicula molestiformis, Entomoneis paludosa, Achnanthe minutisima, Nitzschia dissipata , and Navicula viridula . Each taxon contributes to the overall composition of the diatom community and plays a role in assessing the water quality of the aquatic ecosystem. Navicula radiosa , Nitzschia palea , and Achnanthe minutisima tolerate high conductivity water and high concentrations of nutrients such as nitrites (NO₂⁻), nitrates (NO₃⁻), and orthophosphates (PO₄³⁻). The occurrence of these taxa reflects their ability to acclimate to modification of these conditions, generally due to anthropogenic disturbance, indicating the fact that Oued Beht is subjected to significant pollution (Germain 1981 ). The presence of some members of the species Amphora veneta in the moderately polluted zone points to the intermediate ecological status in which the rate of pollution is not very high and not completely low, creating a survival condition for this species without favoring high diversity (Germain 1981 ). The presence of Cymbella affinis may be an indicator of water quality. In general, its presence indicates quite clean and well-oxygenated waters because it has a tendency to be present in waters of good water quality and low pollution (Germain 1981 ). Diatom Biological Index (IBD) The calculated value of the Diatom Biological Index (IBD) is 15.76 for the Oued Beht, indicating good water quality. This index is the result of an assessment based on the diversity and abundance of diatoms present in the aquatic ecosystem (AFNOR NF T90-354 2007). The apparent contradiction can be explained by the fact that the physico-chemical analyses reflect the current state of the water, while the diatom biological index reflects a historical state. Once of good quality, the water allowed the development of diversified diatoms that, thanks to their tolerance, persist despite the present pollution, thus maintaining a good biological index. CONCLUSION This work contributes to the evaluation of the physico-chemical quality and the diatom biological index of the waters of the Oued Beht, crossing the Middle Atlas of Morocco. Sampling was conducted at the station located near the Oued Beht village during the month of March 2024. The physico-chemical analyses revealed a significant degradation in water quality. Additionally, we identified a diversity of diatoms comprising 15 taxa from 10 genera. The value of the diatom biological index, which was evaluated at 15.76, suggests good water quality, indicating an intermediate ecological balance with moderate pollution. This study demonstrates the close relationship between diatoms and the physico-chemical parameters of the water in the Oued Beht watershed. The main results highlight the impact of temperature, pH, conductivity, and dissolved oxygen on the diatom communities. Furthermore, nitrogen and orthophosphate levels play a crucial role in their composition and distribution. By combining this information, it is possible to conclude that, although the water shows signs of moderate pollution in terms of its physico-chemical characteristics, the biological conditions remain favorable to diatoms, suggesting that pollution has not yet reached a critical level for the majority of aquatic life. Water quality continues to deteriorate, mainly due to domestic wastewater discharges. Environmental management and protection measures are necessary to improve water quality and protect biodiversity in this region. Declarations Competing Interests The authors declare no competing interests. Consent to Participate Not applicable. Consent to Publish All authors have reviewed and approved the final version of the manuscript and consent to its publication. Ethical Compliance Not applicable. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Author Contribution Youssef Ouballouk: Drafted the manuscript, interpreted the results, created the location maps, performed statistical tests, and generated the figures. Abdelkader Chahlaoui: Provided essential guidance in drafting and revising the manuscript, offering critical and intellectual insights. Abdelhak Saidi: Assisted in conducting in situ and laboratory physico-chemical analyses. Chouaib Amahzoune: Co-drafted the manuscript, interpreted the results, provided intellectual insights during in situ and laboratory analyses, and contributed to the selection of the study site. Abdelilah Rahou and Abdelhak Saidi: Played key roles in data collection and presentation, significantly contributing to the organization and visual representation of the research findings. Acknowledgements We express our gratitude to all those who provided expertise and support throughout this research. Special thanks go to the department and faculty members for their invaluable assistance. Availability of Data and Materials The datasets used and analyzed during the current study are available from the corresponding author, Youssef Ouballouk, upon reasonable request. References Abdallaoui A, Derraz M, Bhenabdallah MZ, Lek S (1998) Contribution to the study of the relationship among different forms of phosphorus in the sediments of a eutrophic reservoir in a Mediterranean climate (El Kansera, Morocco). Rev Sci Eau 11(1):101–116 AFNOR (2007) Standard NF T90-354: Water quality – Guidance for the determination of the Diatom Biological Index (IBD). AFNOR, Paris Ács É, Ari E, Duleba M, Dressler M, Genkal SI, Jakó É, Rimet F, Ector L, Kiss KT (2016) Pantocsekiella, a new centric diatom genus based on morphological and genetic studies. Fottea 16:56–78 Bélanger M, El-Jabi N, Caissie D, Ashkar F, Ribi JM (2005) Water temperature prediction using neural networks and multiple linear regression. Rev Sci Eau 18(3):403–421 Ben Moussa A, Chahlaoui A, Rour H (2012) Assessment of physicochemical pollution of the Oued Khoumane waters (Moulay Idriss Zerhoun, Morocco). International Journal of Biological and Chemical Sciences, 6(6), pp. 7096–7111. https://doi.org/10.4314/ijbcs.v6i6.44 Bey MY, Ector L (2013) Atlas des diatomées des cours d’eau de la région Rhône-Alpes. Tome 5: Naviculacées, Cymbelloïdées, Gomphonématoïdées. Direction Régionale de l’Environnement, de l’Aménagement et du Logement Rhône-Alpes, pp 751–972 Bouaicha R, Benabdelfadel A (2010) Variability and management of surface waters in Morocco. Sécheresse 21:325–326. https://doi.org/10.1684/sec.2010.0272 Cantonati M, Lange-Bertalot H, Angeli N (2011) Neidiomorpha gen. nov. (Bacillariophyta): A new freshwater diatom genus separated from Neidium Pfitzer. Bot Stud 51:195–202 C.E.P.A (1997) Public health goal for nitrate and nitrite in drinking water. California Environmental Protection Agency. Chahlaoui A (1996) Hydrobiological study of the Oued Boufekrane (Meknès), impact on the environment and health. Dissertation, University of Moulay Ismail. Daide F, Afgane R, Lahrach A, Chaouni AA (2022) Beht Watershed (Morocco) rainfall-runoff simulation with the HEC-HMS hydrological model. Ecol Eng Environ Technol. https://doi.org/10.12912/27197050/142942 Derwich E, Benaabidate L, Zian A, Sadki O, Belghity D (2010) Caractérisation physico-chimique des eaux de la nappe alluviale du haut Sebou en aval de sa confluence avec oued Fès. Larhyss J 8:101–112 Dib I (2009) L'impact de l'activité agricole et urbaine sur la qualité des eaux souterraines de la plaine de Gadaine-Ain Yaghout (Est Algérien). Master’s thesis, Faculty of Engineering Sciences, Department of Hydraulics, Hadj Lakhdar Batna University, Batna, 127 pp Dynesius M, Nilsson C (1994) Fragmentation and flow regulation of river systems. Science 266(5186):753–762. https://doi.org/10.1126/science.266.5186.753 El Guamri Y, Belghyti D (2007) Contamination of wastewater in the liquid sanitation network by parasitic helminth eggs (case of the city of Kenitra, Morocco). Rev Microbiol Ind San Environ 1:44–59 Germain H (1981) Flora of diatoms: freshwater and brackish waters of France. Société Nouvelle des Éditions Boubée, Paris Graça MAS, Capitulo AR, Ocón C, Gómez N (2002) In situ tests for water quality assessment: A case study in Pampean rivers. Water Res 36(16):4033–4040. https://doi.org/10.1016/S0043-1354(02)00132-X Hébert S, Légaré S (2000) Monitoring the quality of rivers and small streams. Environmental Monitoring Directorate, Ministry of the Environment, Québec, Report No. QE-123, Envirodoq No. ENV-2001-0141, 24 pp Jonnalagadda SB, Mhere G (2001) Water quality of the Odzi River. Water Research 35(10):2371–2376. https://doi.org/10.1016/S0043-1354(00)00533-9 Lamhasni N, Chillasse L, Timallouka M (2016) Bio-evaluation of surface water quality of Oued Beht (Morocco) using the Global Biological Index for Control and Surveillance Networks (IBG-RCS). Eur Sci J 13(3):94. https://doi.org/10.19044/esj.2016.v13n3p94 Lange-Bertalot H, Krammer K (1989) Achnanthes : Eine Monographie der Gattung. Bibliotheca Diatomologica, vol 18. 393 pp Lange-Bertalot H (2001) The genus Navicula sensu stricto: 10 genera separated from Navicula sensu lato Frustulia. In: Lange-Bertalot H (ed) Diatoms of Europe, vol 2. A.R.G. Gantner Verlag K.G., Ruggell, 526 pp Lavoie I, Hamilton PB, Campeau S, Grenier M, Dillon PJ (2008) Guide to the identification of diatoms from rivers in Eastern Canada. Presses de l’Université du Québec, Québec, 241 pp Levkov Z, Caput Mihalić K, Ector L (2010) A taxonomical study of Rhoicosphenia Grunow (Bacillariophyceae) with a key for identification of selected taxa. Fottea 10:145–200 Ministry of Environment of Morocco (2002) Surface water quality grid. Decree No. 1275-01 of October 17, 2002. https://www.environnement.gov.ma/fr/78-cat1/1008-normes-de-qualite-des-eaux-de-surfaces Neal C, Neal M, Wickham H, Harrow M (2000) The water quality of a tributary of the Thames, the Pang, southern England. Sci Total Environ 251–252:459–475. https://doi.org/10.1016/S0048-9697(00)00399-5 Ongley ED (2001) Water Quality Programs in Developing Countries. Water International 26(1):14–23. https://doi.org/10.1080/02508060108686883 Ouarrak K (2022) Study of the physico-chemical, bacteriological, and parasitological quality of the waters of Oued Ouislane and Oued Bouishak in the city of Meknes and their potential impact on the environment and health. Doctoral thesis, Moulay Ismail University, Morocco Rodier J, Legube B, Merlet N et al (2009) Water analysis: Natural waters, wastewater, seawater, chemistry, physico-chemistry, microbiology, biology, interpretation of results, 9th edn. Dunod, Paris Sacchi CF, Testard P (1971) Ecologie animale: Organismes et milieu. Doin, Paris Taffouo VD, Ikoli Saya RA, Mbeng LO, Eyango MT (2017) Impacts of physicochemical water characteristics on the distribution of phytoplankton and macrophytes in the Nkam River (Cameroon). Int J Biol Chem Sci 11(4). https://doi.org/10.4314/ijbcs.v11i4.28 Van der Werff A (1995) A new method of concentrating and cleaning diatoms and other organisms. In: Proceedings of the International Association of Theoretical and Applied Limnology, vol 12, pp 276–277 World Health Organization (WHO) (1986) Guidelines for Drinking-Water Quality . World Health Organization. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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2022)\u003c/p\u003e","description":"","filename":"image1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6264926/v1/a5fbddcd5ec40502e15eba40.jpeg"},{"id":90899884,"identity":"24595db5-dfec-40dd-a88a-f4ff319e69d5","added_by":"auto","created_at":"2025-09-09 12:07:11","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":664961,"visible":true,"origin":"","legend":"\u003cp\u003eDiatom\u003csub\u003e \u003c/sub\u003especies\u003csub\u003e \u003c/sub\u003ein\u003csub\u003e \u003c/sub\u003eOued\u003csub\u003e \u003c/sub\u003eBeht: (1) \u003cem\u003eNavicula radiosa,\u003c/em\u003e (2) \u003cem\u003eStauroneis phoenicenteron\u003c/em\u003e, (3) \u003cem\u003eNavicula gregaria, \u003c/em\u003e(4) \u003cem\u003eNavicula molestiformis, \u003c/em\u003e(5)\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eEntomoneis\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003epaludosa,\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e(6) \u003cem\u003eNavicula\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003ediclivis,\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e(7)\u003csub\u003e \u003c/sub\u003e\u003cem\u003eAmphora\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eveneta,\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e(8)\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003ePinnularia\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eviridis\u003c/em\u003e, (9)\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eAchnanthes\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eminutissima,\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e(10)\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eNitzschia\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003epalea,\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e(11)\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eCyclotella\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003emeneghiniana,\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e(12)\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eNavicula\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eviridula,\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e(13)\u003csub\u003e \u003c/sub\u003e\u003cem\u003eSurirella\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eovalis, \u003c/em\u003e(14)\u003csub\u003e \u003c/sub\u003e\u003cem\u003eCymbella\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eaffinis,\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e(15)\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003eNitzschia\u003c/em\u003e\u003csub\u003e\u003cem\u003e \u003c/em\u003e\u003c/sub\u003e\u003cem\u003edissipata\u003c/em\u003e\u003c/p\u003e","description":"","filename":"image2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6264926/v1/a7e2c179dd9418c609ea0c50.jpg"},{"id":90899885,"identity":"c85f9fbe-ba52-4726-aa24-9478309f8d2a","added_by":"auto","created_at":"2025-09-09 12:07:17","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1529575,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6264926/v1/d432bedc-e8a3-4a15-927c-0e275453463f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Diatom Diversity in the Surface Waters of Oued Beht","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eWater is a fundamental component of life and a critical resource for all ecosystems. Protecting water quality is essential for sustaining biodiversity, human health, and ecosystem services. Rivers, as dynamic systems, play a vital role in recharging groundwater, supporting biodiversity, facilitating organic matter cycling, and maintaining ecological balance (Dynesius and Nilsson \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1994\u003c/span\u003e; Gra\u0026ccedil;a et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). However, increasing anthropogenic activities have led to widespread pollution, causing significant physical and chemical alterations that degrade water quality (Taffouo et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) and disrupt the distribution and abundance of aquatic organisms.\u003c/p\u003e\u003cp\u003eIn Morocco, water resources face multiple threats, including a semi-arid to arid climate, recurrent droughts, and high-water consumption (Bouaicha and Benabdelfadel \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). These challenges are exacerbated by pollution from domestic, agricultural, and industrial discharges (Chahlaoui \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1996\u003c/span\u003e). As a result, assessing water quality has become a pressing concern (Ongley \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2001\u003c/span\u003e), with pollution risks influenced by the physical, chemical, and biological characteristics of contaminants (Jonnalagadda and Mhere \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). Numerous studies have documented the alarming degradation of continental ecosystems in the region (Abdallaoui et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1998\u003c/span\u003e), underscoring the need for comprehensive monitoring and management strategies.\u003c/p\u003e\u003cp\u003eThis study focuses on Oued Beht, a 4,500 km\u0026sup2; watershed in northwestern Morocco within the Sebou basin. The river is bordered by the Gharb plain, Meknes plateau, Oum-Er-Rbia basin, Bouregreg basin, and the Middle Atlas (Abdallaoui et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1998\u003c/span\u003e). Oued Beht is subject to significant anthropogenic pressures, including the influence of the Kensra dam, domestic wastewater discharges, agricultural runoff, and hydrocarbon pollution. These factors contribute to elevated organic and chemical pollution levels, disrupting the aquatic ecosystem and threatening species distribution, groundwater quality, and overall ecosystem health (Lamhasni et al. 2017).\u003c/p\u003e\u003cp\u003eDiatoms, a key component of aquatic ecosystems, are widely recognized as effective bioindicators of water quality due to their sensitivity to environmental changes and their ability to integrate variations in physicochemical properties. They are particularly useful for assessing organic pollution and eutrophication (Lavoie et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). In this study, we employ diatom-based indices to evaluate the water quality of Oued Beht, providing insights into both current conditions and historical trends. By combining physicochemical analyses with diatom community assessments, we aim to offer a holistic understanding of the river\u0026rsquo;s ecological status and inform sustainable management practices.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy Area\u003c/h2\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe Oued Beht watershed is located upstream of the El Kansra dam, approximately 85 km from Rabat, traversing the Middle Atlas of Morocco. The main watercourse, Oued Beht, is a tributary of the Sebou River (Daide et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Stretching over 110 km, it originates near Azrou as a result of the confluence between the Oued Tigrigra and the Oued Amghass. The selection of the station is based on three main criteria: the water flow rate of the Oued, the direction of flow, and finally the station\u0026rsquo;s accessibility. We conducted our sampling campaign in Oued Beht in March 2024 at the station whose location is shown in Fig.\u0026nbsp;1.\u003c/p\u003e\u003cp\u003eFigure 1. Study Area Station (Daide et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003ePhysicochemical measurements\u003c/h3\u003e\n\u003cp\u003ePhysicochemical analyses were conducted following the standardized techniques outlined by Rodier et al. (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). A total of 13 parameters were assessed, with some measured directly in the field and others analyzed in the laboratory.\u003c/p\u003e\u003cp\u003eIn situ measurements were conducted using calibrated portable instruments, while laboratory analyses were performed within 24 hours of sampling, following standardized methods described by Rodier et al. (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Details of the methods, instruments, and units are provided in (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePhysicochemical parameters measured in the field and analyzed in the laboratory, methods, and instruments used.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMeasurement Method\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUnit\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003eIn-Situ Measurements\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTemperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThermometer\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026deg;C\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTurbidity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTurbidimeter (PCE-PHD 1 model)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eFTU\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDissolved Oxygen\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDO meter (PCE-PHD 1 model)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003emg/l\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eConductivity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eConductivity meter (PCE-PHD 1 model)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026micro;S/cm (20\u0026deg;C)\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSalinity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSalt meter (PCE-PHD 1 model)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003emg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epH\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003epH meter\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026ndash;14\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003eLaboratory Analyses\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChlorides\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMohr Method\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003emg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSulfates\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNephelometry \u0026ndash; sulfates are precipitated in a hydrochloric Environment as barium sulfate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003emg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCalcium\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMolecular Absorption Spectrometry\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003emg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOrtho Phosphates\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMolecular Absorption Spectrometry\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003emg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNitrates\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSodium Salicylate Method\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003emg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBOD₅\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBOD EVO Sensor System 6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003emg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNitrites\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMolecular Absorption Spectrometry\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003emg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\n\u003ch3\u003eDiatoms sampling\u003c/h3\u003e\n\u003cp\u003eSamples were collected by scrubbing a 100 cm\u0026sup2; area of rock surface, and the resulting material was transferred into 30 ml bottles containing a 4% formaldehyde preservative solution for transport to the laboratory. To remove organic matter and carbonates, samples were treated with 25\u0026ndash;30 ml of 30% hydrogen peroxide (H2O2) at 100\u0026deg;C for 1.5 hours, followed by 10 ml of hydrochloric acid (HCl) at 120\u0026deg;C for 2 hours (Van der Werff \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1995\u003c/span\u003e). Oxidation byproducts were eliminated through repeated rinsing and settling with distilled water. Diatom suspensions were then prepared on coverslips and mounted on slides using Zrax (MicrAP, Pennsylvania). Light microscopy (LM) images were obtained using a NIKON Eclipse Ci microscope equipped with a Nikon DS-Fi1 camera.\u003c/p\u003e\u003cp\u003eDiatom identification was conducted using taxonomic references, including works by Germain (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e1981\u003c/span\u003e), Lange-Bertalot \u0026amp; Krammer (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1989\u003c/span\u003e), Lange-Bertalot (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2001\u003c/span\u003e), Levkov et al. (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2010\u003c/span\u003e), Cantonati et al. (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), Bey \u0026amp; Ector (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), and \u0026Aacute;cs et al. (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe Diatom Biological Index (IBD) is calculated based on the identification and quantification of diatom species present in a sample. Species abundance is determined by counting a minimum of 300 valves, as outlined in the AFNOR NF T90-354 (2007) standard. This index is fixed based on knowledge of the ecology of each species and its probability of occurrence in different water quality classes. The abundance of each species in the sample is considered to build a representative profile of the diatom community, which is then converted into another IBD score ranging from 1 to 20. This score reflects the level of ecosystem pollution, particularly by nitrogen and phosphorus nutrients, as well as organic matter (AFNOR NF T90-354 2007) (Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eIBD values, corresponding classes, and ecological status\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIBD Value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17 to 20\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13 to 17\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9 to 13\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5 to 9\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1 to 5\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eClass\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eA\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eB\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003eD\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003eE\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEcological State\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eVery good state\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eGood state\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003eModerate state\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003ePoor state\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003eVery poor state\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"RESULTS AND DISCUSSION","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003ePhysico-chemical parameters\u003c/h2\u003e\u003cp\u003eThe recorded levels of the studied physico-chemical parameters are illustrated in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eThe measured water temperature is 16.6\u0026deg;C, a critical factor for aquatic organisms since it influences both biochemical and biological processes, and sudden changes can disrupt ecosystems; anthropogenic factors such as wastewater discharge, agricultural drainage, and industrial effluents further impact temperature by affecting oxygenation, solubility, and metabolism, which in turn influence diatom development (B\u0026eacute;lange et al. 2005; Ben Moussa et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe pH of 9.63 exceeds Moroccan standards (6.5\u0026ndash;8.5) (Ministry of Environment of Morocco \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2002\u003c/span\u003e), indicating high alkalinity likely due to human activities (El Guamri et al. 2007; Neal et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2000\u003c/span\u003e), while conductivity is 9690 \u0026micro;S/cm at 20\u0026deg;C, far above the Moroccan standard (1300\u0026ndash;2700 \u0026micro;S/cm), suggesting a high dissolved ion concentration from both natural and anthropogenic sources (Dib, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eTurbidity is 42.34 NTU, which, although within Moroccan limits (5\u0026ndash;50 NTU) (Ministry of Environment of Morocco \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2002\u003c/span\u003e), remains high enough to indicate possible pollution (Ouarrak \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e); salinity is 5.3 g/L, exceeding the 2 g/L standard and reflecting influences from geological factors and human activities (WHO 1986, Rodier et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eDissolved oxygen measures 8 mg/L, surpassing the surface water standard of 5 mg/L and indicating non-polluted conditions (H\u0026eacute;bert and L\u0026eacute;gar\u0026eacute; \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2000\u003c/span\u003e), while sulfates at 296 mg/L slightly exceed the 200\u0026ndash; 250 mg/L standard, likely resulting from gypsum dissolution and soil leaching, as well as the influence of domestic wastewater (Rodier et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eNitrates are at 1.52 mg/L, well below the 25\u0026ndash;50 mg/L limit and originating from organic matter and fertilizers, indicating some pollution (Derwich et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; C.E.P.A \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1997\u003c/span\u003e), whereas nitrites at 0.778 mg/L exceed the 0.1 mg/L standard, suggesting incomplete ammonium oxidation or nitrate reduction and serving as a sign of organic pollution (Sacchi and Testard \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1971\u003c/span\u003e). The BOD5 is 6 mg/L, within the 5\u0026ndash;10 mg/L standard, reflecting oxygen consumption by microorganisms due to soil leaching (Ben Moussa et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), and orthophosphates are measured at 0.633 mg/L, surpassing the \u0026lt;\u0026thinsp;0.5 mg/L threshold for preventing eutrophication, mainly due to inputs from agriculture, household waste, and fertilizers (Hammami et al. 2005).\u003c/p\u003e\u003cp\u003eChlorides are recorded at 731 mg/L, close to the upper Moroccan limit of 300\u0026ndash;750 mg/L, with peaks in inhabited areas (Rodier et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), and calcium is found at 112 mg/L, indicating a significant presence influenced by both geology and human activities (Rodier et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eResults of Physico-Chemical Parameters\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eValue\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAir and Water Temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e16.6\u0026deg;C\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDissolved Oxygen (DO)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8 mg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epH\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9.63\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eConductivity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9690 \u0026micro;S/cm\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSalinity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5.3 mg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTurbidity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e42.34 NTU\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChlorides\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.778 mg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSulfates\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e296 mg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOrtho Phosphates\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.633 mg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNitrates\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.52 mg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBOD₅\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6 mg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCalcium\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e112 mg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNitrites\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.778 mg/L\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eComposition of diatom communities\u003c/h2\u003e\u003cp\u003eIn terms of diatoms, we identified a total of 15 taxa belonging to 10 genera (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e5\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This demonstrates a great diversity of diatom flora. Such diversity reflects an ability to adapt to a wide range of environmental conditions, including high levels of pollution.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eDiatom Taxa of Oued Beht\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTaxon\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAbundance (\u0026permil;)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eNavicula radiosa K\u0026uuml;tzing, 1844\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e327.92\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eStauroneis phoenicenteron (Nitzsch) Ehrenberg, 1843\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e36.93\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eNavicula gregaria Donkin, 1861\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e51.70\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eSurirella ovalis (K\u0026uuml;tzing) K\u0026uuml;tzing, 1844\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e26.59\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eNavicula molestiformis (Hustedt) Hustedt, 1956\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e106.35\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eEntomoneis paludosa (Brun) Cleve, 1894\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e73.86\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eAchnanthes minutissima (K\u0026uuml;tzing) Cleve, 1894\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e93.06\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003ePinnularia viridis (K\u0026uuml;tzing) Cleve, 1894\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e14.77\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eCymbella affinis (K\u0026uuml;tzing) K\u0026uuml;tzing, 1844\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e17.73\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eNitzschia palea (K\u0026uuml;tzing) W. Smith, 187\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e36.93\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eNitzschia dissipata Hustedt, 1956\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e109.31\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eCyclotella meneghiniana (K\u0026uuml;tzing) Hustedt, 1930\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e22.16\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eNavicula viridula K\u0026uuml;tzing, 1844\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e75.33\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eAmphora veneta (K\u0026uuml;tzing) K\u0026uuml;tzing, 1844\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e7.39\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe results show that the diatom flora is dominated (more than 71% of the 677 individuals identified in each sample) by four genera: \u003cem\u003eNavicula, Entomoneis, Achnanthe\u003c/em\u003e, and \u003cem\u003eNitzschia\u003c/em\u003e. them, the most frequent species are: \u003cem\u003eNavicula radiosa, Navicula gregaria, Navicula molestiformis, Entomoneis paludosa, Achnanthe minutisima, Nitzschia dissipata\u003c/em\u003e, and \u003cem\u003eNavicula viridula\u003c/em\u003e. Each taxon contributes to the overall composition of the diatom community and plays a role in assessing the water quality of the aquatic ecosystem. \u003cem\u003eNavicula radiosa\u003c/em\u003e, \u003cem\u003eNitzschia palea\u003c/em\u003e, and \u003cem\u003eAchnanthe minutisima\u003c/em\u003e tolerate high conductivity water and high concentrations of nutrients such as nitrites (NO₂⁻), nitrates (NO₃⁻), and orthophosphates (PO₄\u0026sup3;⁻). The occurrence of these taxa reflects their ability to acclimate to modification of these conditions, generally due to anthropogenic disturbance, indicating the fact that Oued Beht is subjected to significant pollution (Germain \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e1981\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe presence of some members of the species \u003cem\u003eAmphora veneta\u003c/em\u003e in the moderately polluted zone points to the intermediate ecological status in which the rate of pollution is not very high and not completely low, creating a survival condition for this species without favoring high diversity (Germain \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e1981\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe presence of \u003cem\u003eCymbella affinis\u003c/em\u003e may be an indicator of water quality. In general, its presence indicates quite clean and well-oxygenated waters because it has a tendency to be present in waters of good water quality and low pollution (Germain \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e1981\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eDiatom Biological Index (IBD)\u003c/h3\u003e\n\u003cp\u003eThe calculated value of the Diatom Biological Index (IBD) is 15.76 for the Oued Beht, indicating good water quality. This index is the result of an assessment based on the diversity and abundance of diatoms present in the aquatic ecosystem (AFNOR NF T90-354 2007).\u003c/p\u003e\u003cp\u003eThe apparent contradiction can be explained by the fact that the physico-chemical analyses reflect the current state of the water, while the diatom biological index reflects a historical state. Once of good quality, the water allowed the development of diversified diatoms that, thanks to their tolerance, persist despite the present pollution, thus maintaining a good biological index.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThis work contributes to the evaluation of the physico-chemical quality and the diatom biological index of the waters of the Oued Beht, crossing the Middle Atlas of Morocco. Sampling was conducted at the station located near the Oued Beht village during the month of March 2024.\u003c/p\u003e\u003cp\u003eThe physico-chemical analyses revealed a significant degradation in water quality. Additionally, we identified a diversity of diatoms comprising 15 taxa from 10 genera. The value of the diatom biological index, which was evaluated at 15.76, suggests good water quality, indicating an intermediate ecological balance with moderate pollution.\u003c/p\u003e\u003cp\u003eThis study demonstrates the close relationship between diatoms and the physico-chemical parameters of the water in the Oued Beht watershed. The main results highlight the impact of temperature, pH, conductivity, and dissolved oxygen on the diatom communities. Furthermore, nitrogen and orthophosphate levels play a crucial role in their composition and distribution.\u003c/p\u003e\u003cp\u003eBy combining this information, it is possible to conclude that, although the water shows signs of moderate pollution in terms of its physico-chemical characteristics, the biological conditions remain favorable to diatoms, suggesting that pollution has not yet reached a critical level for the majority of aquatic life.\u003c/p\u003e\u003cp\u003eWater quality continues to deteriorate, mainly due to domestic wastewater discharges. Environmental management and protection measures are necessary to improve water quality and protect biodiversity in this region.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eCompeting Interests\u003c/h2\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003ch2\u003eConsent to Participate\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eConsent to Publish\u003c/h2\u003e\n\u003cp\u003eAll authors have reviewed and approved the final version of the manuscript and consent to its publication.\u003c/p\u003e\n\u003ch2\u003eEthical Compliance\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThis research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eYoussef Ouballouk: Drafted the manuscript, interpreted the results, created the location maps, performed statistical tests, and generated the figures. Abdelkader Chahlaoui: Provided essential guidance in drafting and revising the manuscript, offering critical and intellectual insights. Abdelhak Saidi: Assisted in conducting in situ and laboratory physico-chemical analyses. Chouaib Amahzoune: Co-drafted the manuscript, interpreted the results, provided intellectual insights during in situ and laboratory analyses, and contributed to the selection of the study site. Abdelilah Rahou and Abdelhak Saidi: Played key roles in data collection and presentation, significantly contributing to the organization and visual representation of the research findings.\u003c/p\u003e\n\u003ch2\u003eAcknowledgements\u003c/h2\u003e\n\u003cp\u003eWe express our gratitude to all those who provided expertise and support throughout this research. Special thanks go to the department and faculty members for their invaluable assistance.\u003c/p\u003e\n\u003ch2\u003eAvailability of Data and Materials\u003c/h2\u003e\n\u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author, Youssef Ouballouk, upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAbdallaoui A, Derraz M, Bhenabdallah MZ, Lek S (1998) Contribution to the study of the relationship among different forms of phosphorus in the sediments of a eutrophic reservoir in a Mediterranean climate (El Kansera, Morocco). Rev Sci Eau 11(1):101\u0026ndash;116\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAFNOR (2007) Standard NF T90-354: Water quality \u0026ndash; Guidance for the determination of the Diatom Biological Index (IBD). AFNOR, Paris\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e\u0026Aacute;cs \u0026Eacute;, Ari E, Duleba M, Dressler M, Genkal SI, Jak\u0026oacute; \u0026Eacute;, Rimet F, Ector L, Kiss KT (2016) Pantocsekiella, a new centric diatom genus based on morphological and genetic studies. Fottea 16:56\u0026ndash;78\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eB\u0026eacute;langer M, El-Jabi N, Caissie D, Ashkar F, Ribi JM (2005) Water temperature prediction using neural networks and multiple linear regression. Rev Sci Eau 18(3):403\u0026ndash;421\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBen Moussa A, Chahlaoui A, Rour H (2012) Assessment of physicochemical pollution of the Oued Khoumane waters (Moulay Idriss Zerhoun, Morocco). International Journal of Biological and Chemical Sciences, 6(6), pp. 7096\u0026ndash;7111. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4314/ijbcs.v6i6.44\u003c/span\u003e\u003cspan address=\"10.4314/ijbcs.v6i6.44\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBey MY, Ector L (2013) Atlas des diatom\u0026eacute;es des cours d\u0026rsquo;eau de la r\u0026eacute;gion Rh\u0026ocirc;ne-Alpes. Tome 5: Naviculac\u0026eacute;es, Cymbello\u0026iuml;d\u0026eacute;es, Gomphon\u0026eacute;mato\u0026iuml;d\u0026eacute;es. Direction R\u0026eacute;gionale de l\u0026rsquo;Environnement, de l\u0026rsquo;Am\u0026eacute;nagement et du Logement Rh\u0026ocirc;ne-Alpes, pp 751\u0026ndash;972\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBouaicha R, Benabdelfadel A (2010) Variability and management of surface waters in Morocco. S\u0026eacute;cheresse 21:325\u0026ndash;326. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1684/sec.2010.0272\u003c/span\u003e\u003cspan address=\"10.1684/sec.2010.0272\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCantonati M, Lange-Bertalot H, Angeli N (2011) Neidiomorpha gen. nov. (Bacillariophyta): A new freshwater diatom genus separated from Neidium Pfitzer. Bot Stud 51:195\u0026ndash;202\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eC.E.P.A (1997) Public health goal for nitrate and nitrite in drinking water. California Environmental Protection Agency.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChahlaoui A (1996) Hydrobiological study of the Oued Boufekrane (Mekn\u0026egrave;s), impact on the environment and health. Dissertation, University of Moulay Ismail.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDaide F, Afgane R, Lahrach A, Chaouni AA (2022) Beht Watershed (Morocco) rainfall-runoff simulation with the HEC-HMS hydrological model. Ecol Eng Environ Technol. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.12912/27197050/142942\u003c/span\u003e\u003cspan address=\"10.12912/27197050/142942\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDerwich E, Benaabidate L, Zian A, Sadki O, Belghity D (2010) Caract\u0026eacute;risation physico-chimique des eaux de la nappe alluviale du haut Sebou en aval de sa confluence avec oued F\u0026egrave;s. Larhyss J 8:101\u0026ndash;112\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDib I (2009) L'impact de l'activit\u0026eacute; agricole et urbaine sur la qualit\u0026eacute; des eaux souterraines de la plaine de Gadaine-Ain Yaghout (Est Alg\u0026eacute;rien). Master\u0026rsquo;s thesis, Faculty of Engineering Sciences, Department of Hydraulics, Hadj Lakhdar Batna University, Batna, 127 pp\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDynesius M, Nilsson C (1994) Fragmentation and flow regulation of river systems. Science 266(5186):753\u0026ndash;762. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1126/science.266.5186.753\u003c/span\u003e\u003cspan address=\"10.1126/science.266.5186.753\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEl Guamri Y, Belghyti D (2007) Contamination of wastewater in the liquid sanitation network by parasitic helminth eggs (case of the city of Kenitra, Morocco). Rev Microbiol Ind San Environ 1:44\u0026ndash;59\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGermain H (1981) Flora of diatoms: freshwater and brackish waters of France. Soci\u0026eacute;t\u0026eacute; Nouvelle des \u0026Eacute;ditions Boub\u0026eacute;e, Paris\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGra\u0026ccedil;a MAS, Capitulo AR, Oc\u0026oacute;n C, G\u0026oacute;mez N (2002) In situ tests for water quality assessment: A case study in Pampean rivers. Water Res 36(16):4033\u0026ndash;4040. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0043-1354(02)00132-X\u003c/span\u003e\u003cspan address=\"10.1016/S0043-1354(02)00132-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eH\u0026eacute;bert S, L\u0026eacute;gar\u0026eacute; S (2000) Monitoring the quality of rivers and small streams. Environmental Monitoring Directorate, Ministry of the Environment, Qu\u0026eacute;bec, Report No. QE-123, Envirodoq No. ENV-2001-0141, 24 pp\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJonnalagadda SB, Mhere G (2001) Water quality of the Odzi River. Water Research 35(10):2371\u0026ndash;2376. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0043-1354(00)00533-9\u003c/span\u003e\u003cspan address=\"10.1016/S0043-1354(00)00533-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLamhasni N, Chillasse L, Timallouka M (2016) Bio-evaluation of surface water quality of Oued Beht (Morocco) using the Global Biological Index for Control and Surveillance Networks (IBG-RCS). Eur Sci J 13(3):94. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.19044/esj.2016.v13n3p94\u003c/span\u003e\u003cspan address=\"10.19044/esj.2016.v13n3p94\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLange-Bertalot H, Krammer K (1989) \u003cem\u003eAchnanthes\u003c/em\u003e: Eine Monographie der Gattung. Bibliotheca Diatomologica, vol 18. 393 pp\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLange-Bertalot H (2001) The genus Navicula sensu stricto: 10 genera separated from Navicula sensu lato Frustulia. In: Lange-Bertalot H (ed) Diatoms of Europe, vol 2. A.R.G. Gantner Verlag K.G., Ruggell, 526 pp\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLavoie I, Hamilton PB, Campeau S, Grenier M, Dillon PJ (2008) Guide to the identification of diatoms from rivers in Eastern Canada. Presses de l\u0026rsquo;Universit\u0026eacute; du Qu\u0026eacute;bec, Qu\u0026eacute;bec, 241 pp\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLevkov Z, Caput Mihalić K, Ector L (2010) A taxonomical study of Rhoicosphenia Grunow (Bacillariophyceae) with a key for identification of selected taxa. Fottea 10:145\u0026ndash;200\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMinistry of Environment of Morocco (2002) Surface water quality grid. Decree No. 1275-01 of October 17, 2002. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.environnement.gov.ma/fr/78-cat1/1008-normes-de-qualite-des-eaux-de-surfaces\u003c/span\u003e\u003cspan address=\"https://www.environnement.gov.ma/fr/78-cat1/1008-normes-de-qualite-des-eaux-de-surfaces\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNeal C, Neal M, Wickham H, Harrow M (2000) The water quality of a tributary of the Thames, the Pang, southern England. Sci Total Environ 251\u0026ndash;252:459\u0026ndash;475. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0048-9697(00)00399-5\u003c/span\u003e\u003cspan address=\"10.1016/S0048-9697(00)00399-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOngley ED (2001) Water Quality Programs in Developing Countries. Water International 26(1):14\u0026ndash;23. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/02508060108686883\u003c/span\u003e\u003cspan address=\"10.1080/02508060108686883\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOuarrak K (2022) Study of the physico-chemical, bacteriological, and parasitological quality of the waters of Oued Ouislane and Oued Bouishak in the city of Meknes and their potential impact on the environment and health. Doctoral thesis, Moulay Ismail University, Morocco\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRodier J, Legube B, Merlet N et al (2009) Water analysis: Natural waters, wastewater, seawater, chemistry, physico-chemistry, microbiology, biology, interpretation of results, 9th edn. Dunod, Paris\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSacchi CF, Testard P (1971) Ecologie animale: Organismes et milieu. Doin, Paris\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTaffouo VD, Ikoli Saya RA, Mbeng LO, Eyango MT (2017) Impacts of physicochemical water characteristics on the distribution of phytoplankton and macrophytes in the Nkam River (Cameroon). Int J Biol Chem Sci 11(4). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4314/ijbcs.v11i4.28\u003c/span\u003e\u003cspan address=\"10.4314/ijbcs.v11i4.28\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVan der Werff A (1995) A new method of concentrating and cleaning diatoms and other organisms. In: Proceedings of the International Association of Theoretical and Applied Limnology, vol 12, pp 276\u0026ndash;277\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWorld Health Organization (WHO) (1986) \u003cem\u003eGuidelines for Drinking-Water Quality\u003c/em\u003e. World Health Organization.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Oued Beht, water, physico-chemical, diatom, biological index","lastPublishedDoi":"10.21203/rs.3.rs-6264926/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6264926/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eDiatoms, known for their rapid response to environmental changes, are widely recognized as reliable bioindicators of water quality. Despite their ecological significance, studies on diatom flora in North Africa, particularly in Morocco, remain scarce. This study evaluates the water quality of Oued Beht in northwestern Morocco by integrating physico-chemical analyses with diatom community assessments.\u003c/p\u003e\u003cp\u003eSampling conducted in March 2024 at a representative site revealed elevated pH (9.63), high conductivity (9690 \u0026micro;S/cm), and increased salinity (5.3 mg/L), indicative of significant anthropogenic pressures from domestic, agricultural, and industrial discharges. In contrast, diatom community composition, dominated by pollution-tolerant taxa such as Navicula radiosa (represented by 15 taxa), yielded a diatom biological index (IBD) of 15.76, suggesting relatively good historical water quality.\u003c/p\u003e\u003cp\u003eThis apparent discrepancy underscores the resilience and ecological memory of diatom communities, which may reflect past conditions even as current physico-chemical parameters indicate moderate environmental degradation. These findings highlight the importance of adopting a holistic approach to monitoring aquatic ecosystem health in Morocco, combining biological and physico-chemical indicators to better understand and manage anthropogenic impacts.\u003c/p\u003e","manuscriptTitle":"Diatom Diversity in the Surface Waters of Oued Beht","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-09 12:07:07","doi":"10.21203/rs.3.rs-6264926/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"54b1fd02-226d-4e25-971d-0014cb02c0b8","owner":[],"postedDate":"September 9th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-09T12:07:07+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-09 12:07:07","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6264926","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6264926","identity":"rs-6264926","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}