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One of the major challenges of aquatic ecology is to understand how anthropization affects biodiversity and what the consequences on the functioning of hydrosystems. Physicochemical and zoolanktonic variables studied in two ponds (Mokolo and Mopa) in the city of Bertoua, with two sampling stations (surface and depth) per pond and data collected monthly from March 2016 to April 2017 (14 months) allowed us to appreciate the spatial and seasonal dynamics of zooplankton in relation to anthropogenic disturbances. Abiotic variables of the ponds show that they are highly anthropized with relatively high temperatures (> 23 °C), low water transparency (< 70 cm) despite the shallow depth of the ponds (< 170 cm), average oxygenation (> 50%) with hypoxia (< 35%) recorded in the rainy season, high mineralization of the waters, high levels of nutrients, organic matter and photosynthetic pigments (> 30 µg/L). These characteristics allow to classify these water bodies in the category of hypereutrophic ponds. Biological data show fairly diverse ponds with 63 species identified in Mokolo Pond representing 17.89% of the total abundance. In Mopa Pond, 75 species were identified representing 21.30% of the total abundance. This study allowed us to deduce that the structure and dynamics of microcrustaceans communities are under the control of different processes that interact simultaneously. It is mainly influenced by the season, predation and by the depth of sampling, the month and the station having no influence on this distribution.&nbsp

espanolSe caracterizan y evaluan los bosques de Quercus petraea del Pais Vasco y Navarra. Tres son las ubicaciones elegidas: sur de Bizkaia, sur de Guipuzcoa y norte de Navarra. Se acomete un inventariado de 10 parcelas por cada ubicacion y se analizan diferentes caracteristicas: diversidad especifica, filiacion corologica, estatus de las especies y aplicacion del metodo LANBIOEVA. Estos robledales son muy escasos dentro de la Peninsula Iberica y cuentan con cortejos donde dominan tambien las plantas escasas. En estos bosques, en general, dominan las filiaciones eurosiberianas o euroasiaticas, atlanticas y de transicion entre el mediterraneo y el atlantico. Las formaciones de Navarra se configuran como las mas diversas, seguidas por las de Guipuzcoa y las de Vizcaya. La evaluacion biogeografica da lugar a altos valores (por encima de los 1.200 puntos) para los tres robledales, pero superiores en Pikandi (Gipuzkoa) y Garralda (Navarra) y mas modestos en Garrastatxu (Bizkaia EnglishThe forests of Quercus petraea of the Basque Country and Navarre They are characterized and evaluate. Three are the locations chosen: south of Vizcaya, south of Guipuzcoa and north of Navarra. An inventory of 10 plots is undertaken for each location and different characteristics are analyzed: diversity, chorological affiliation, species status and application of the LANBIOEVA method. These oak forests are very scarce and have courtships where scarce plants also dominate. In these forests, dominate, in general, eurosiberian or Eurasian, Atlantic and transitional affiliations between the Mediterranean and the Atlantic. The oak forests of Navarra are configured as the most diverse, followed by Guipuzcoa and Vizcaya. Biogeographic evaluation results in high values for the three formations but higher in Pikandi and Garralda and more modest in Garrastatxu.

In order to evaluate the taxonomic composition of phytoplankton, monthly monitoring of the composition and distribution of phytoplankton communities was conducted during the spring period of 2018, at three stations in Imessouane Bay. The systematic study of the samples revealed the presence of 74 phytoplankton species with a dominance of diatoms (69%) over dinoflagellates (31%). The specific diversity was estimated by calculating the specific richness, Shannon-Weaver Diversity Index (H’), Pielou's evenness index (J), Margalef (Mg) and Simpson (Ds). The use of these indices concomitantly has clearly identified the overall state of the living phytoplankton community in Imessouane Bay. The presence of potentially harmful species was detected during the study period but still in small quantities, these mainly belong to the genera (Pseudo-nitzschia, Dinophysis, Prorocentrum, and Alexandrium)., Journal of Applied Science and Environmental Studies, Vol 3, No 3 (2020)

Here we presented some theoretical conclusions about the nonlinear links in island bird communities. It is proved, that the relations between the specific biodiversity, structure and entropy of biogeocenosis are nonlinear. The optimal level of diversity in island bird communities does not depend on the carrying capacity. The optimal level of species diversity and the corresponding value of the total population (biomass) increases with carrying capacity and available ecological niches. The population diversity is the basis for community adaptation towards the unstable environment. Species diversity allows the community as a whole to be more efficient and to use the resources of environment more efficient by differentiating of ecological niches. The species diversity indices do not strive to stable constant, they increase along with species abundance but these dependences are rather nonlinear.

International audience; Grain legumes meet several agricultural challenges in the perspective of ecological intensification: not only they have the ability to fix atmospheric nitrogen, which make them highly suitable for lowinput system and lead to reduced energy use, but also they can deliver other services. They represent affordable sources of protein for human consumption and a source of diversification to break pest and weeds cycles and optimize nutrient management. However, the specific diversity of pulses is poorly represented in most cropping systems despite the growing demand from food chains. While over than 80 pulses are consumed by humans, the FAO database covers only 11 pulse species. The number of released cultivars is also very low: in France, for example, only 7 chickpeas cultivars are available in the French market, while more than 90,000 accessions are recorded in the world’s genetic resources. The objective of this study is to characterize the genetic diversity of a wide range of species and varieties of pulses through a functional approach that links agro-morphological traits, physiological functions and ecosystem services. Three ecosystem services have been identified as crucial for Mediterranean cropping systems: 1) yield production and stability under dry conditions (i.e; drought resistance), 2) nitrogen fixation and accumulation in the plant for future return to the soil, and 3) competitiveness toward weeds. An extensive literature review (120 ref.) allowed us to identify and document 41 species regarding a set of 12 traits (e.g. maximum plant height, leaf size, days to maturity…). The full data was then analyzed with CART regressions. As an example, drought resistance was well predicted by the maximum height, day to flowering, seed size, and leaf size. Plants with small leaves, short cycles and short height are most likely to be more resistant than others. Species were then assembled into groups of species with similar patterns of ecosystem services, according to their agro-morphological traits. These results allow a better understanding of how specific diversity of grain legumes is organized and can be used with respects to target ecosystem services.

The observations carried-out in 2008/2010 to ornamental plants from parks and greenhouses of ADP Pitesti relieve 12 species of thrips. One species of them, Frankliniella occidentalis was identified in greenhouses on Rosa sp., Dianthus sp. and Zantedeschia sp. In parks, the thrips species belong to 12 species, dominated by Frankliniella intonsa. All of them are polypfagous and divided in two throphic levels: primary and secondary consumers. The thrips species are mentioned for the first time in Romania on this host plant. In greenhouses are necessary intensive chemical treatments and methods of cultural hygiene to limit the F. occidentalis populations.

Les forêts néotropicales accueillent une importante biodiversité encore méconnue. L’intégrité des écosystèmes naturels est menacée par les changements environnementaux (e.g., réchauffement climatique, destruction des habitats), par conséquent, identifier les facteurs structurants, naturels et anthropiques, du fonctionnement des écosystèmes, représente un défi scientifique crucial. L’inhérente complexité de ces milieux diversifiés pose de nombreux problèmes conceptuels et logistiques comme un échantillonnage exhaustif et/ou l’identification des espèces. Les broméliacées à réservoirs sont des écosystèmes miniatures adéquats pour pallier ces difficultés, car elles retiennent de l’eau de pluie et accumulent de la matière organique au creux de leurs feuilles, permettant ainsi de supporter des réseaux trophiques simples d’invertébrés aquatiques. Elles peuvent être échantillonnées exhaustivement, ont une forte abondance locale, et une large aire de répartition. De l’échelle locale à biogéographique, les travaux de cette thèse visent d’abord à comprendre comment ces communautés se structurent en réponse à l’hétérogénéité naturelle des forêts amazoniennes (e.g., ouverture de la canopée, fluctuations climatiques saisonnières), puis tente de prédire, par le biais d’expérimentations in situ et au laboratoire les réponses structurelles et fonctionnelles de ces communautés à divers scénarios de changement climatique. Une attention particulière a été portée sur l’impact de la température et des précipitations sur la physiologie et le comportement d’espèces clefs, et sur les interactions trophiques au sein des communautés. En dépit d’un renouvellement important des espèces d’invertébrés entre localités, les principales fonctions écosystémiques (e.g., décomposition) sont assurées de façon constante par un cœur densément connecté de détritivores et de micro-organismes. Ce cœur fonctionnel est présent sur l’ensemble de l’aire de distribution des broméliacées à réservoirs, et alimenté par la chute de litière et de cadavres d’invertébrés terrestres. La dynamique des populations et des communautés s’est révélée plus stable que supposé face aux perturbations appliquées dans ces travaux. Cette stabilité est conférée par les caractéristiques morphologiques de la plante hôte qui tamponnent les fluctuations environnementales, par les différents traits de résistances des espèces d’invertébrés, et par la ségrégation spatio-temporelle des niches des espèces. Ces différentes approches empiriques et expérimentales ont permis de mettre en évidence des interactions entre les changements environnementaux et la réponse des communautés qui soient indépendantes des échelles spatiales considérées et qui sembleraient communes à divers écosystèmes de plus grandes tailles., Neotropical forests shelter an astonishing and underrated biodiversity. The integrity and stability of these natural ecosystems are threatened by human-induced environmental changes. Therefore, highlighting the determinants of ecosystem functioning, be they natural or anthropogenic, is a daunting but paramount scientific challenge. The intrinsic complexity of highly diversified ecosystems arouses both conceptual and logistical difficulties, which we handle, by manipulating tiny ecosystems, the tank bromeliads. The leaves of tank bromeliads form wells that hold rainwater and intercept leaf litter, allowing for a simple invertebrate aquatic community to thrive. These plants can be exhaustively sampled, are naturally replicated, and widely distributed. From local to biogeographic scales, this thesis aims at understanding how these communities respond to the natural heterogeneity of Amazonian forests, and at predicting the impacts of human-induced disturbances on the structure and functioning of these communities, using in situ and lab experiments. Particular focus is attributed to the influence of some aspects of climate changes (e.g., warming, and various precipitations scenarios) on individual physiology, behavior, and trophic interactions. Despite a high turnover in invertebrate species composition across localities (influence of local factors and historical processes), main ecosystem functions were consistently ensured by a densely interconnected core of detritivores and microorganisms. This functional core was found in all studied localities and unceasingly fueled by leaf litter and terrestrial invertebrate carcasses. Regarding the disturbances we applied, the dynamics of populations and communities were more stable than expected. This stability is conferred by the morphology of the host plant, the resistance traits of aquatic invertebrates and the spatial-temporal segregation of species niches, which altogether buffered fluctuations in environmental conditions. The various empirical and manipulative approaches used in this thesis have highlighted interactions between environmental changes and the responses of communities that are independent of the spatial scales considered and may be shared by several ecosystems varying in size.

Microorganisms are essential for the maintenance and functioning of the ecosystems. In some food products, microbial community, mainly composed by yeasts and lacid actic bacteria which ferment sugars, positively affects organoleptic qualities and shelf life of the product. It is the case of bread sourdough. This PhD aimed at describing yeast diversity patterns of organic French bread sourdoughs and conserving a part of this diversity. Using cultural-Based and non-Cultural based analyses of yeast diversity, we highlighted a unique specific diversity of each sourdough. We also shown the predominance of Kazachstania genus and a convergence of sourdoughs’ yeasts isolates for the ability to consume raffinose and sucrose. Although density and species composition varied between sourdoughs, no spatial pattern was highlighted. Bread-Making practices and their effects on microbial communities’ diversity were also analyzed. Two bread-Making practice typologies (quite « intensive » and quite « extensive »), affecting dominant yeast species were also revealed.; Les microorganismes sont essentiels au maintien et au fonctionnement des écosystèmes. Dans certains produits alimentaires, la communauté microbienne, composée principalement de levures et de bactéries lactiques, fermente les sucres, affecte positivement les qualités organoleptiques du produit et augmente sa durée de conservation. C’est le cas du levain de panification. Cette thèse visait principalement à décrire les patterns de diversité des levures de levains français produits à partir de farine issue de l’agriculture biologique et à conserver une partie de cette diversité. Grâce à des méthodes d’analyses culturales et non culturales de la diversité des levures, nous avons mis en évidence une diversité spécifique caractéristique de chaque levain étudié. Nous avons aussi montré la dominance du genre Kazachstania et la convergence des souches isolées de levain pour la capacité à consommer du raffinose et du saccharose. Bien que la densité et la composition en espèces varient entre deux levains, aucune structuration spatiale de la diversité n’a été mise en évidence. Les pratiques de panification et leurs effets sur la diversité des communautés microbiennes ont également été analysés. Deux typologies de pratiques de panification (plutôt « intensives » et plutôt « extensives »), affectant l’espèce dominante des populations de levures, ont été révélées.

The depiction of the phylogenetic structure of the genus Frankia is still troublesome and the evolutionary forces guiding the speciation, dispersion and diversity are not well documented. The current phylogeny has been defined on the basis of the comparative analysis of the 16S rRNA gene sequence while de genomospecies definition is still subjected to DNA-DNA hybridization trials. Aiming to bring to light the genomic variability of the genus and its translation into the ecological and specific diversity, our studies consisted in, firstly, evaluating the specific diversity within the genus and the ability of the Amplified Fragment Length Polymorphism technique (AFLP) to describe Frankia genomospecies and their phylogenetic liaisons. Moreover this technique was also tested for the study of the non isolated Frankia directly in the actinorhizal nodules. Secondly, we defined a MLSA (Multilocus Sequence analysis) scheme which allowed us to establish a phylogeny of the genus by using a hundred of strains and for the first time to describe the phylogenetic divergence of a group of non culturable strains exhibiting the particular ability (phenotype) of sporulating in planta (Sp+). The Sp+ strains are distributed into two divergent clades whose structure is highly correlated to the host genotype. The importance of genetic markers having impact over ecology of the strains has been revised. In this regard we have studied the phylogenetic analysis and the occurrence of the genetic components for the siderophore production and of the sodF gene in Frankia.; La définition de la structure phylogénétique du genre Frankia est encore problématique, les forces évolutives guidant son spéciation, dispersion et donc la génération de sa diversité ne sont pas complètement documentées. La phylogénie actuelle du genre a été définie par l’analyse comparative de la séquence du 16S rRNA. Par ailleurs, la définition des espèces génomiques a été gênée par la faible applicabilité de la technique d’hybridation ADN-ADN. Dans le cadre de cette thèse nos travaux ont consisté à étudier la variabilité génomique dans le genre et sa conséquente traduction en variabilité spécifique et écologique. Dans un premier temps, nous avons évalué la diversité spécifique du genre ainsi que l’utilité de la technique AFLP (Amplified Fragment Length Polymorphism) pour la définition des espèces génomiques. De plus, notre protocole fut aussi utilisé pour analyser souches non isolées en appliquant le protocole directement sur des nodosités actinorhiziennes. Dans un deuxième temps, un schéma MLSA (Multilocus Sequence Analysis) nous a permis de redéfinir la phylogénie du genre sur une centaine de souches, et pour la première fois de décrire la divergence phylogénétique d’un groupe de souches non-isolées présentant un phénotype unique de sporulation in planta (Sp+). Les souches Sp+ sont distribuées dans deux clades très divergents dont la structuration est fortement corrélée au génotype de la plante hôte et au phénotype Sp+/Sp- de la souche. L’intérêt de marqueurs génétiques présentant un intérêt pour l’écologie des souches a été révisé. Dans ce but nous avons étudié la présence, distribution et phylogénie de sodF et des différents composants génétiques impliquées dans la production des siderophores chez Frankia.

As part of the project “Global changes in river systems: effects on biodiversity, food web and system functioning” fish community of La Choza stream was initially estimated and then compared with existing literature of pampean plain streams. From May 2007 to June 2008 five fish samples were taken in two sampling stations. Species occurrence, diversity (H´) and evenness (J) were estimated. Similarity in species composition with ten pampean streams was performed using cluster analysis. 2935 specimens collected represented 23 species (13 permanent, 7 semi-permanent and 3 occasional) and 10 families. Characiformes and Siluriformes were dominant. Although species richness was similar in both sites, diversity index was higher at downstream station. Differences between stations could be related to channel shape, bottom profile and sediment type. The cluster analysis showed that position of the water course within the basin and pollution are both important in the ichthyofauna composition determination., Instituto de Limnología "Dr. Raúl A. Ringuelet"

L'évolution spatio-temporelle, qualitative et quantitative du peuplement phytoplanctonique a été suivie au lac municipal de Yaoundé. Pour cela des prélèvements hebdomadaires ont été effectués de novembre 1996 à décembre 1997, au niveau d'une station de la zone centrale du lac.Trois descripteurs (indice de diversité spécifique, régularité et diagrammes rangs-fréquences) ont été utilisés pour l'analyse de la dynamique de la structure du peuplement. L'indice de diversité spécifique obtenu à partir des biomasses spécifiques, par la formule dérivée de celle de SHANNON et WEAVER (1949), est compris entre 0,68 et 4,64 bits/µg. La régularité (PIELOU, 1966) varie de 0,14 à 0,84; les faibles valeurs correspondant dans l'ensemble à la présence des espèces fortement dominantes. Les profils des diagrammes rangs-fréquences, établis en coordonnées log-log, associés aux faibles valeurs de la diversité, sont essentiellement caractéristiques des stades pionniers (1 et 1') de l'évolution d'un lac tel que décrits par MARGALEF (1967) et FRONTIER (1976). Le stade 2 est rare alors que le stade 3 est absent.Une analyse simultanée basée sur les variations spatio-temporelles de la densité cellulaire et de l'indice de diversité spécifique, sur les valeurs de la régularité, et sur les profils des diagrammes rangs-fréquences révèle le caractère immature permanent des populations phytoplanctoniques inféodées à ce biotope, et caractérise ainsi un milieu eutrophe à hypereutrophe où aucun stade d'équilibre n'est atteint. La richesse du milieu en éléments biogènes et sa faible profondeur (Zmax=4,3 m) sont à l'origine de sa vulnérabilité. L'événement susceptible d'interrompre la succession des populations s'est avéré être le brassage des eaux, provoqué aussi bien par les pluies que les vents dont l'énergie cinétique est fréquemment suffisante pour entraîner un brassage complet d'une colonne d'eau de hauteur aussi faible., The Yaounde municipal lake (3°52'N, 11°32'E) is a shallow hypertrophic water body (Z max=4.3 m), situated downstream from Yaounde. It is an artificial lake resulting from a dam constructed in 1951 across a small river named Mingoa. Like many other water bodies in urbanised areas, this ecosystem switched rapidly from being mesotrophic to hypertrophic during the 1980's, due to the expansion of human activity and an inefficient treatment of wastewater in its catchment area. This study was carried out with the objective to analyse the ecological succession and the spatio-temporal fluctuations of the phytoplankton population structure in this shallow equatorial lake. Samples were collected at weekly intervals from November 1996 to December 1997, at a station near its central zone (depth=3.5 m), using an opaque horizontal PVC Van Dorn sampler. Sampling operations were conducted at the following levels: surface; -0.5 m; -1 m; -1.5 m and -2.5 m.Individual phytoplankton from 1% iodine acid preserved subsamples (BOURRELLY, 1990) were enumerated with an inverted microscope (Olympus CK2) at 200X magnification, using a Sedgwick-Rafter counting cell, according to UTHERMÖHL (1958). At least 400 individuals (colonies, bundles or trichomes, depending on existing life forms) were counted on each subsample. Specific biomass was then obtained using the biovolume method. To evaluate the population structure dynamics, the SHANNON and WEAVER (1949) specific diversity index method and the evenness (PIELOU, 1966) method were computerized using specific biomass, the evenness being the ratio between the real and the maximal diversity (log2 S, where S is the number of species). Also, rank-frequency diagrams were carried out in logarithmic co-ordinates according to FRONTIER (1969), using integrated samples obtained from grab samples collected over the entire water column.Cell densities were highest in the uppermost meter of the water column at the beginning of the rainy season, due to the exponential development of species such as Planktothrix mougeotii, Chlamydomonas sp., Eudorina elegans, Euglena gracilis, Gonyostomum semen, Euglena texta, Phacus helicoïdes, Closterium limneticum, Cryptomonas ovata, Peridinium cf. gutwinskii, Trachelomonas hispida var. crenulatocollis and Cyclotella meneghiniana. The specific diversity index varied 0.68 and 4.64 bits/µg, and values gradually decreased from the first uppermost meter to the bottom of the water column. Evenness varied from 0.14 to 0.84 with a somewhat similar spatio-temporal variation as the diversity index. Low values of these descriptors generally correspond to the presence of a highly dominant species. The rank-frequency diagrams were mainly S-shaped, indicating the predominance of one species which in this study was either Chlamydomonas sp or Planktothrix mougeotii.A simultaneous analysis of the ecological succession and the spatio-temporal variations of the phytoplanktonic structure revealed that the functioning of this ecosystem was essentially allogenic in nature and was strongly influenced by the supply of decayed organic matter from the Mingoa stream, and effluents from ministerial buildings and hotels located near the lake. This permanent supply of abundant biogenic elements, coupled with the low depth of the ecosystem, makes it vulnerable. Ecological succession, frequently limited to the pioneer stages (1 and 1'), reflected the briefness of the different phases of phytoplankton growth, and the consequences of disturbances regularly undergone by the phytoplankton community. The second stage was scarcely reached while the third was absent. These successions were mainly controlled by rainfall, as well as wind, which is responsible for the mixing of such a shallow water column. These results can be considered important for the Yaounde municipal lake and other water bodies close to densely populated areas in Cameroon for which there is no management plan. Urgent actions need to be carried out to rehabilitate this ecosystem that fluctuates between the eutrophic and hypertrophic status.

Sont considérés dans cette étude, l’impact des rejets polluants d’origines urbaine et industrielle sur la qualité des eaux du Mfoundi, l’abondance, la richesse spécifique et la structure des communautés diatomiques qui peuplent ce cours d’eau. Le calcul du pourcentage de taxons tolérants à la pollution organique a permis d’évaluer la réponse de ces algues à l’enrichissement du milieu en matières organiques. Les analyses physico-chimiques des eaux mettent en évidence l’existence d’un gradient de pollution croissant de l’amont à l’aval de la rivière. Le cours supérieur présente des eaux turbides avec des teneurs élevées de matières en suspension. Les cours moyen et inférieur sont fortement contaminés par les matières organiques qu’apportent les eaux usées domestiques et les effluents industriels qu’ils reçoivent. Au total, 237 taxons de diatomées épilithiques, majoritairement cosmopolites, appartenant à 39 genres répartis dans 25 familles, ont été inventoriés. Le développement dans le cours supérieur du Mfoundi de taxons tels que Gomphonema parvulum (Kützing) Kützing et variétés, Gomphonema gracile Ehrenberg et Navicula radiosa Kützing, est associé essentiellement à la turbidité des eaux de ce tronçon. La distribution de Nitzschia palea (Kützing) W. Smith, Navicula geoppertiana (Bleisch) Grunow, Navicula mutica Kützing et Pinnularia subcapitata Gregory dans les cours moyen et inférieur est étroitement liée à la charge organique et la forte minéralisation des eaux. N. palea est l’espèce la plus abondante dans les stations Mf5 (66 %) et Mf6 (53 %), indiquant une importante pollution organique de ces sites sous l’effet des rejets des industries brassicoles et vinicoles opérant dans leur voisinage. La variation spatiale de la diversité spécifique n’a pas souligné toute l’ampleur de l’altération de la qualité des eaux; toutefois, l’analyse du pourcentage de taxons polluo-tolérants révèle que les apports graduels en nutriments et en matières organiques dans les cours moyen et inférieur contribuent à l’eutrophisation progressive de ces secteurs. Il est montré que les diatomées épilithiques sont sensibles à la variation de la qualité de l’eau du Mfoundi, et peuvent être utilisées comme bioindicateurs de l’état de santé des cours d’eau urbains du Cameroun., The Mfoundi River is used for the disposal of solid wastes and waste waters from domestic and industrial activities, which can alter its water quality and biodiversity. The aim of this study was to assess the structure of diatom communities in the Mfoundi River in relation to some physico-chemical variables, i.e., analyzing the changes in species composition and the dominance profile of the main species along a pollution gradient. The diversity metrics (species richness, Shannon’s diversity index, evenness) and the percent pollution tolerant valves (%PTV) were also tested to characterize the water quality and the response of diatoms to environmental enrichment in organic matter. The physico-chemical analyses of the waters revealed a gradient of increasing pollution from upstream to downstream of the river. The upper reach presented turbid waters with high levels of suspended solids. The middle and the lower reaches were highly contaminated with organic matters originating from domestic sewage and industrial effluents. A total of 237 epilithic diatom taxa, mostly cosmopolitan, belonging to 39 genera distributed among 25 families were inventoried. The development in the upper reach of the Mfoundi of taxa such as Gomphonema parvulum (Kützing) Kützing and varieties, Gomphonema gracile Ehrenberg, and Navicula radiosa Kützing reflected in particular the turbid waters of this section. The distribution of Nitzschia palea (Kützing) W. Smith, Navicula geoppertiana (Bleisch) Grunow, Navicula mutica Kützing, and Pinnularia subcapitata Gregory in the middle and lower reaches was closely related to the organic load and high degree of mineralisation of the waters. N. palea was the most abundant species at the stations Mf5 (66%) and Mf6 (53%), indicating a significant organic contamination of these sites under the effect of discharges from brewery and wine-making industries operating within their vicinity. The spatial variation of diversity metrics did not reflect the full extent of the alteration of water quality, but the analysis of the %PTV revealed that incremental inputs of nutrients and organic matter in the middle and lower reaches of the Mfoundi may be contributing to the start of the eutrophication process in these sectors. This study showed that epilithic diatoms are sensitive to the variations in water quality of the Mfoundi, and can be used as bioindicators of the health status of urban streams in Cameroon.