anthropic impact

Depuis le XIX e siècle, la Saône retient l'attention des chercheurs, nombreux à avoir étudié les particularités de sa dynamique alluvionnaire, notamment entre Villefranche-sur-Saône et Lyon. Des études paléoenvironnementales se sont ajoutées aux études géologiques depuis les années 1980, à la faveur de grands travaux d'aménagement réalisés dans le lit majeur de la rivière ou de prospections archéologiques en lit mineur et en lit majeur. Deux transects ont été réalisés à partir de carottages dans le paléochenal de Boitrait à Saint-Georges-de-Reneins (Rhône) et dans celui de la Serrée à Simandre (Saône-et-Loire). Ils ont permis des analyses polliniques et des datations 14 C-AMS sur lesquelles s'appuient les hypothèses concernant la dynamique de la Saône dans ces deux secteurs depuis le Tardiglaciaire. Ces analyses fournissent également des éléments de connaissance sur l'anthropisation du lit majeur en complétant utilement ainsi les données de l'archéologie. Les chenaux étudiés renseignent sur des phases d'activation de la dynamique fluviale et de dépôt depuis le creusement du Bølling ; elles diffèrent d'un secteur à l'autre, notamment en fonction de la nature du style fluvial du fond de vallée.

Anthropic impact of the Barva aquifer (Heredia, Costa Rica) with emphasis on land use (1992-2006). The advance of urbanization in the Central Valley of Costa Rica is having negative impacts on land use and stresses the environment with a high demand of natural resources, particularly water resources. One example is the Barva Water Table, one of the main water suppliers of semi-urban areas of the Greater Metropolitan Area of Costa Rica, which leads to conflicts between social actors involved with this resource. Comparing land use maps of the area defined by Act LXV of 1888, as well as the literature, we found that forest cover is decreasing while area covered by crops and pastures has increased from 1992 and 2006. At the same time, the forest area has undergone a process of fragmentation, and the increasing number of forest patches has an edge effect in all classes of land use. We recommend sustainable governance of water resources in the protected area's buffer zone, with the participation of the local government, development associations, and other related public and private institutions.

An analysis of the faunal affinities among 731 sampling stations on a territory of 74 600 km 2 in the South of France along the Mediterranean shore, has resulted in a définition of faunal areas, which are assembled in faunal régions. This analysis of the affinities using the point corrélation coefficient, allows one to conceive in a synthetic way the faunal complex of a large région and to point out the transition sectors through which the passage of one type of faunal complex to another occur. Thèse complexes are outlined on a map, and their main aspects are analysed. L'approche écologique de la répartition des Scarabéides coprophages montre que ceux-ci réagissent à de nombreux facteurs du milieu. Leurs réponses multiples tiennent compte de la diversité de ces variables écologiques et se traduisent par des modèles de distribution régionale très variés (LUMARET, 1978 b). Une analyse de la répartition d'une centaine d'espèces distribuées dans le sud de la France laisse déjà percevoir des peuplements différents selon que l'on considère les régions montagneuses ou les plaines, les régions calcaires ou cristallines, ou bien encore les territoires

Bats are key components of ecological networks, and studies in degraded areas are especially important to understand the impact of the human settlements on bats communities. Here, we surveyed the bat fauna in Guaribas Biological Reserve, a protected area in the Atlantic Forest in Paraiba state, northeastern Brazil, and compared it with the bat fauna that occupies the nearby villages. In the villages, we recorded 650 individuals from 14 species, while 1,127 individuals from 20 species were recorded in the Reserve. Diversity estimation pointed out 19 species for the settlements, and 22 for the Reserve. A Bray-Curtis/Sorensen similarity cluster analysis informed that the Reserve areas and the villages form two distinct groups. Additionally, a Wilcox test pointed out that both areas have significantly distinct abundances and species richnesses. Only a subset of the assemblage, mainly formed by generalist or opportunist species, occupies the villages, exploring resources that are offered...

Las actividades humanas en los sistemas naturales promueven cambios que ponen en peligro a las comunidades acuáticas por pérdida de nichos ecológicos generando disminución de la riqueza y diversidad. El objetivo de esta investigación fue analizar los ensambles de aves y peces asociados a cuatro bañados de arroyos pampeanos con usos del suelo periurbano y rural en sus cuencas. Los resultados evidenciaron que existen importantes diferencias en la composición y estructura de dichos ensambles según la cuenca de pertenencia. Los valores más bajos de riqueza y de diversidad se registraron en los sitios periurbanos, donde además se observó la dominancia de las especies más tolerantes de ambos grupos de vertebrados. El estudio en simultáneo de estos ambientes nos permitió registrar de qué manera, en una misma región, los cambios inducidos por el hombre condicionan la configuración de los ensambles de aves y peces. En consecuencia, el análisis multi-taxa realizado no solo resulta de carácter...

The present study seeks to characterize the composition, structure, and functional traits of the tree stratum of a Semideciduous Forest in Pouso Alegre, MG, Brazil (22º12'43"S and 45º59'30"W), by comparing Edge and Interior habitats and their relation to human impacts and soil variables. The tree community (diameter at 1.3 m (DBH) higher than 5 cm) was inventoried using the point-centered quarter method by laying out 12 transects of 450 m each (six transects in the Edge and six in the Interior). Functional traits-wood density and seed mass-were obtained by genus. The impact evaluation and soil sample collection were realized per transect. We found significant differences in terms of the basal area (higher in Interior), diversity (higher in Interior) and community seed mass (higher in Edge). The effects of higher values of soil traits such as Calcium, Magnesium, cation sum (CS) and base saturation (V) on species composition were stronger in the Interior, while human induced impacts and soil Potassium had an overwhelming effect on the Edge.

The spread of carbapenemase-producing bacteria is a worldwide concern as it challenges healthcare, especially considering the insufficient development of antimicrobials. These microorganisms have been described not only in hospitals, but also in several environmental settings including recreational waters. Community exposure to antimicrobial-resistant bacteria through recreation might be relevant for human health, but risk assessment studies are lacking. Absence of effective and feasible monitoring in recreational aquatic matrices contributes to such a knowledge gap. Here, we aimed at assessing predictors of occurrence of medically relevant carbapenemase-producing bacteria in coastal waters. We quantitatively assessed recovery of carbapenemase-producing Enterobacteriaceae, Pseudomonas spp., Acinetobacter spp. and Aeromonas spp. in superficial coastal waters showing distinct pollution history across one year, and registered data regarding tide regimen, 7-days pluviosity, salinity, pH, water temperature. We analyzed data using General Estimating Equation (GEE) to assess predictors of such occurrence. Our results suggest that the sampling site had the strongest effect over concentration of these antimicrobial-resistant microorganisms, followed by pollution indexes and tide regimen. Increased salinity, advanced sampling time, water temperature, rainfall and decrease of pH were related to decrease concentrations. We provide a list of factors that could be easily monitored and further included in models aiming at predicting occurrence of carbapenemase producers in coastal waters. Our study may encourage researchers to further improve this list and validate the model proposed, so that monitoring and future public policies can be developed to control the spread of antimicrobial resistance in the environment.

Ichthyofauna of karstic wetlands under anthropic impact: the "petenes" of Campeche, Mexico. "Petenes" are small springs and associated streams that drain into wetlands near the coast in karstic areas. We studied composition, distribution, and abundance of the ichthyofauna in Los Petenes region (northwest Campeche). Two petenes displaying different degrees and types of anthropic impact were selected, Hampolol and El Remate. Hampolol has a smaller area but a longer derived stream; it is located within a protected area, but has been invaded by tilapia. El Remate is a popular spa, with no tilapia; it has a larger area but a shorter derived stream. At each "petén", several sites in the main spring, the associated stream, and secondary (temporary) springs were sampled in the rainy and dry seasons. Fishing gear was variable (throw net, gill net, small and large seine nets), but effort was uniform. We recorded temperature, dissolved oxygen, salinity, and depth at each site and season; also, we noted the different types and intensities of anthropic impact (channelization, presence of exotic species, recreational use, etc.) at each petén. We compared the petenes in terms of their environmental quality and fish fauna (composition, distribution, abundance, biomass); we also tested for effects of season and site within each petén. The study found 27 species of fishes, included in 18 genera and eight families, 24 species in Hampolol and 20 in El Remate. The geographical range of 'Cichlasoma' salvini, Rivulus tenuis, Phallichthys fairweatheri, Xiphophorus hellerii, and X. maculatus is extended. The dominant species in both seasons was Astyanax (probable hybrids A. aeneus × altior at Hampolol, pure A. altior at El Remate), which contributed most of the abundance and biomass, together with Vieja synspila and Poecilia velifera. A significantly greater overall diversity (H'n=3.31) was recorded in Hampolol compared to El Remate (H'n=2.10). Cluster analysis of sites by species presence allowed distinction of two groupings within each petén: permanent waters (i.e., main spring, stream) vs. temporary sites (secondary springs, which dry out in winter). Environmental parameters (except salinity) presented significant differences by site and season; a canonical correspondence analysis indicated that the distribution of fish assemblages was influenced by the environmental parameters in both seasons. In terms of composition, historical factors play a role in the differences between the fish assemblages of the two petenes, especially concerning the presence of Astyanax hybrids and Xiphophorus spp. in the southern petén (Hampolol) and Poecilia velifera in the northern petén (El Remate).

An analysis of the faunal affinities among 731 sampling stations on a territory of 74 600 km 2 in the South of France along the Mediterranean shore, has resulted in a définition of faunal areas, which are assembled in faunal régions. This analysis of the affinities using the point corrélation coefficient, allows one to conceive in a synthetic way the faunal complex of a large région and to point out the transition sectors through which the passage of one type of faunal complex to another occur. Thèse complexes are outlined on a map, and their main aspects are analysed. L'approche écologique de la répartition des Scarabéides coprophages montre que ceux-ci réagissent à de nombreux facteurs du milieu. Leurs réponses multiples tiennent compte de la diversité de ces variables écologiques et se traduisent par des modèles de distribution régionale très variés (LUMARET, 1978 b). Une analyse de la répartition d'une centaine d'espèces distribuées dans le sud de la France laisse déjà percevoir des peuplements différents selon que l'on considère les régions montagneuses ou les plaines, les régions calcaires ou cristallines, ou bien encore les territoires

Depuis le XIX e siècle, la Saône retient l'attention des chercheurs, nombreux à avoir étudié les particularités de sa dynamique alluvionnaire, notamment entre Villefranche-sur-Saône et Lyon. Des études paléoenvironnementales se sont ajoutées aux études géologiques depuis les années 1980, à la faveur de grands travaux d'aménagement réalisés dans le lit majeur de la rivière ou de prospections archéologiques en lit mineur et en lit majeur. Deux transects ont été réalisés à partir de carottages dans le paléochenal de Boitrait à Saint-Georges-de-Reneins (Rhône) et dans celui de la Serrée à Simandre (Saône-et-Loire). Ils ont permis des analyses polliniques et des datations 14 C-AMS sur lesquelles s'appuient les hypothèses concernant la dynamique de la Saône dans ces deux secteurs depuis le Tardiglaciaire. Ces analyses fournissent également des éléments de connaissance sur l'anthropisation du lit majeur en complétant utilement ainsi les données de l'archéologie. Les chenaux étudiés renseignent sur des phases d'activation de la dynamique fluviale et de dépôt depuis le creusement du Bølling ; elles diffèrent d'un secteur à l'autre, notamment en fonction de la nature du style fluvial du fond de vallée.

altitudes supérieures). Ainsi, du littoral jusqu'aux plus hauts sommets, les zonations altitudinales de la végétation suivantes ont été définies par Gamisans (1999) et représentées sur la Figure 4 :  un étage thermoméditerranéen qui s'étend du littoral jusqu'à 100 m et pouvant atteindre 200 m sur les versants suffisamment exposés. Cet étage n'apparait que dans les secteurs les plus chauds où les températures moyennes annuelles sont proches et supérieures à 16°C. Il couvre une surface réduite en Corse et peu ponctuellement s'interrompre. Il est principalement caractérisé par des formations arbustives à Pistacia lentiscus et des maquis ou bois de Quercus ilex où peuvent apparaître Olea europaea, Euphorbia dendroides, Phillyrea latifolia, Myrtus communis, Juniperus phoenicea subsp. mediterranea ou J. oxycedrus subsp. macrocarpa ;  un étage mésoméditerranéen qui s'étend du littoral (dans les secteurs où le précèdent étage est absent) jusqu'à 700 m sur les ubacs et jusqu'à 900 m sur les adrets, sous des températures moyennes annuelles comprises entre 12 et 16°C. Cet étage couvre les superficies les plus importantes. Il est caractérisé essentiellement par des maquis à bruyères (Erica arborea, E. scoparia) et à Arbutus unedo, mais aussi par des forêts de Quercus ilex, Pinus pinaster, Quercus suber, Quercus pubescens, Castanea sativa, des fruticées basses à Lavandula stoechas, Genista corsica, Teucrium marum et des cistaies (Cistus monspeliensis, C. salviifolius et C. creticus) ; Enfin, à des altitudes excédant notre secteur d'étude mais à titre informatif :  un étage supraméditerranéen (de 500-700 à 900-1000 m dans les ubacs et de 800-1000 à 1200-1350 m dans les adrets) marqué par l'augmentation d'éléments eurosibériens en mélange avec la flore méditerranéenne. Les essences caducifoliées (e.g. Quercus petraea, Q. pubescens, Castanea sativa, Alnus cordata, Ostrya carpinifolia) et les bois mixtes à Taxus baccata et Ilex aquifolium, de Pinus nigra subsp. laricio, augmentent ou apparaissent tandis que disparaissent Arbutus unedo, Lavandula stoechas, Rosmarinus officinalis et Cistus monspeliensis ;  un étage montagnard (de 900-1000 à 1600 m sur les ubacs et de 1300 à 1800 m sur les adrets) où la proportion d'éléments floristiques eurosibériens dépasse celle d'éléments méditerranéens. Quercus ilex, Q. pubescens, Pinus pinaster, Castanea sativa et les bruyères (Erica arborea, E. scoparia) disparaissent alors qu'apparait ou qu'augmente la proportion de Fagus sylvatica, Abies alba et de plantes de la fruticée naine (Juniperus communis subsp. alpina, Berberis aetnensis, Genista lobelii). Les hêtraies et les sapinières (essentiellement aux ubacs) et les forêts de pins laricio (principalement aux adrets) présentent ici leurs plus beaux peuplements ;  un étage cryo-oroméditerranéen localisé sur les adrets et les crêtes entre 1700-1800 et 2200 m. Il est marqué par un climat rigoureux (températures moyennes annuelles entre 3 et 7°C) mais un net assèchement estivale des sols, par la disparition des pins laricio et la présence de fruticées naines à composition floristique proche de l'étage précédent mais où apparaissent des espèces plus alticoles (e.g. Armeria multiceps, Bellardiochloa variegata et Paronychia polygonifolia).

Antibiotic resistance is a matter of global public health concern. Antibiotic resistance isdisseminated by antibiotic resistance genes (ARGs) which are carried by antibiotic resistancebacteria (ARBs). Lotic ecosystems like rivers which has flowing water can spread ARGs fromone location to another. Such dispersion of ARGs can also move through food chains and foodwebs making the spread of antibiotic resistance more complex and widespread. Detection ofthese ARGs is important for understanding the origin and pathways of antibiotic resistancein our waterways. Both culturing and non-culturing methods can be used for detection ofthese ARGs. Overall, understanding the sources, assessing the presence, and determining thedissemination of antibiotic resistance is important for us to understand the level of antibioticpollution in our waterbodies.

REVISTA DEL LABORATORIO TECNOLÓGICO DEL URUGUAY Determinación de potenciales contaminantes inorgánicos en muestras de suelos y aguas del territorio uruguayo en la Antártida Determination of potential inorganic contaminants in samples of soils and waters of the Uruguayan territory in Antarctica

Antibiotic resistance is a matter of global public health concern. Antibiotic resistance isdisseminated by antibiotic resistance genes (ARGs) which are carried by antibiotic resistancebacteria (ARBs). Lotic ecosystems like rivers which has flowing water can spread ARGs fromone location to another. Such dispersion of ARGs can also move through food chains and foodwebs making the spread of antibiotic resistance more complex and widespread. Detection ofthese ARGs is important for understanding the origin and pathways of antibiotic resistancein our waterways. Both culturing and non-culturing methods can be used for detection ofthese ARGs. Overall, understanding the sources, assessing the presence, and determining thedissemination of antibiotic resistance is important for us to understand the level of antibioticpollution in our waterbodies.

Las actividades humanas en los sistemas naturales promueven cambios que ponen en peligro a las comunidades acuáticas por pérdida de nichos ecológicos generando disminución de la riqueza y diversidad. El objetivo de esta investigación fue analizar los ensambles de aves y peces asociados a cuatro bañados de arroyos pampeanos con usos del suelo periurbano y rural en sus cuencas. Los resultados evidenciaron que existen importantes diferencias en la composición y estructura de dichos ensambles según la cuenca de pertenencia. Los valores más bajos de riqueza y de diversidad se registraron en los sitios periurbanos, donde además se observó la dominancia de las especies más tolerantes de ambos grupos de vertebrados. El estudio en simultáneo de estos ambientes nos permitió registrar de qué manera, en una misma región, los cambios inducidos por el hombre condicionan la configuración de los ensambles de aves y peces. En consecuencia, el análisis multi-taxa realizado no solo resulta de carácter...

Depuis le XIX e siècle, la Saône retient l'attention des chercheurs, nombreux à avoir étudié les particularités de sa dynamique alluvionnaire, notamment entre Villefranche-sur-Saône et Lyon. Des études paléoenvironnementales se sont ajoutées aux études géologiques depuis les années 1980, à la faveur de grands travaux d'aménagement réalisés dans le lit majeur de la rivière ou de prospections archéologiques en lit mineur et en lit majeur. Deux transects ont été réalisés à partir de carottages dans le paléochenal de Boitrait à Saint-Georges-de-Reneins (Rhône) et dans celui de la Serrée à Simandre (Saône-et-Loire). Ils ont permis des analyses polliniques et des datations 14 C-AMS sur lesquelles s'appuient les hypothèses concernant la dynamique de la Saône dans ces deux secteurs depuis le Tardiglaciaire. Ces analyses fournissent également des éléments de connaissance sur l'anthropisation du lit majeur en complétant utilement ainsi les données de l'archéologie. Les chenaux étudiés renseignent sur des phases d'activation de la dynamique fluviale et de dépôt depuis le creusement du Bølling ; elles diffèrent d'un secteur à l'autre, notamment en fonction de la nature du style fluvial du fond de vallée.

Riparian forests and environments close to watercourses support high biodiversity, which may be modified by human activities. In the Paraná River Delta region, cattle raising is one of the activities with the greatest impact, altering vegetation structure. These changes are reflected in bird communities that inhabit these environments. We hypothesize that the absence of large herbivores (whether cows or native deer) will produce an increase in the vegetation cover of the lower strata of forests, due to the greater height of the herbaceous stratum and greater coverage of the shrub stratum, and that these changes mainly affect the species of birds that use resources associated with these strata. Our objective was to understand the changes in richness and abundance of the bird community among different types of cattle management using a functional aggregation approach of bird species. In the areas with cattle, we found less coverage of the shrub layer, lower height of the herbaceous layer and fewer climbing vines. We found that changes in richness and abundance of bird community were strongly related to species associated with the lower vegetation strata (ground-feeding guild, shrub guild and low canopy guild), and that the responses of the different guilds were not homogeneous. Understanding the direction of changes in bird 2 communities occurring in response to modifications of the environment, allows us to optimize conservation efforts. If these efforts are based on conservation of the environment in its natural state, we should adjust the management of the herbivory to the pristine conditions of the environment. On the other hand, if conservation efforts are based on particular species or groups of species associated with certain resources, the correct management of herbivory by cattle can be essential to obtain successful results.

The present study seeks to characterize the composition, structure, and functional traits of the tree stratum of a Semideciduous Forest in Pouso Alegre, MG, Brazil (22º12'43"S and 45º59'30"W), by comparing Edge and Interior habitats and their relation to human impacts and soil variables. The tree community (diameter at 1.3 m (DBH) higher than 5 cm) was inventoried using the point-centered quarter method by laying out 12 transects of 450 m each (six transects in the Edge and six in the Interior). Functional traits-wood density and seed mass-were obtained by genus. The impact evaluation and soil sample collection were realized per transect. We found significant differences in terms of the basal area (higher in Interior), diversity (higher in Interior) and community seed mass (higher in Edge). The effects of higher values of soil traits such as Calcium, Magnesium, cation sum (CS) and base saturation (V) on species composition were stronger in the Interior, while human induced impacts and soil Potassium had an overwhelming effect on the Edge.

Cette thèse a pour objectif d’identifier les trajectoires plurimillénaires des écosystèmes de Corse à basse et moyenne altitude sous la triple influence des forçages climatiques, eustatiques et anthropiques à travers l’étude des assemblages d’insectes fossiles et des données paléobotaniques disponibles ou nouvellement acquises. Cette approche multidisciplinaire a été appliquée sur trois séquences sédimentaires prélevées à l’étang du Greco sur l’île Cavallo, au marais de Cannuta et à la tourbière de Bagliettu.Les résultats obtenus révèlent des changements majeurs dans la structuration du couvert végétal. Des signes d’ouverture du paysage apparaissent sur Cavallo et à Cannuta dès 5500-5000 cal. BP. Ils coïncident avec des indices d’activités des sociétés insulaires, lesquelles s’intensifient après 3000 cal. BP et plus particulièrement depuis 1000 ans à Bagliettu. Notre étude suggère que la sensibilité et la réponse des zones humides littorales face à la remontée relative du niveau mar...

Antimicrobial resistance (AMR) in pathogens has been associated mainly with excessive use of antibiotics. Most studies of resistance have focused on clinical pathogens; however, microorganisms are exposed to numerous anthropogenic substances. Few studies have sought to determine the effects of chemical substances on microorganisms. Exposure to these substances may contribute to increased rates of AMR. Understanding microorganism communities in natural environments and AMR mechanisms under the effects of anthropogenic substances, such as pesticides, is important to addressing the current crisis of antimicrobial resistance. This report draws attention to molecules, rather than antibiotics, that are commonly used in agrochemicals and may be involved in developing AMR in non-clinical environments, such as soil. This report examines pesticides as mediators for the appearance of AMR, and as a route for antibiotic resistance genes and antimicrobial resistant bacteria to the anthropic envir...

The environment plays a key role in the spread and persistence of antimicrobial resistance (AMR). Antimicrobials and antimicrobial resistance genes (ARG) are released into the environment from sources such as wastewater treatment plants, and animal farms. This study describes an approach guided by spatial mapping to quantify and predict antimicrobials and ARG in Minnesota’s waterbodies in water and sediment at two spatial scales: macro, throughout the state, and micro, in specific waterbodies. At the macroscale, the highest concentrations across all antimicrobial classes were found near populated areas. Kernel interpolation provided an approximation of antimicrobial concentrations and ARG abundance at unsampled locations. However, there was high uncertainty in these predictions, due in part to low study power and large distances between sites. At the microscale, wastewater treatment plants had an effect on ARG abundance (sul1 and sul2 in water; blaSHV, intl1, mexB, and sul2 in sedim...

This study simulated nitrogen-compound concentration changes in rivers, taking into account uncertainty analysis carried out by the Monte Carlo Method. The study area is the final stretch of the Piracicaba River, located in Minas Gerais, Brazil, which is an important Doce River tributary. The uncertainty analysis took into account random generation of hydrodynamic variables, initial water quality conditions and kinetic constants. Different variation percentages for the organic nitrogen decay kinetic constants random generation did not influence considerably the ammonia or organic nitrogen maximum concentration extreme values. In the simulations, maximum organic nitrogen concentrations were most frequently between 0.20 mg.L-1 and 0.22 mg.L-1 (42%), maximum ammonia nitrogen between 0.28 mg.L-1 and 0.30 mg.L-1 (30%), maximum nitrite between 0.05 mg.L-1 and 0.07 mg.L-1 (49%) and maximum nitrate between 0.46 mg.L-1 and 0.50 mg.L-1 (37%). Estimated maximum concentrations for ammonia nitrogen, nitrite and nitrate did not exceed the environmental quality standards established by Brazilian CONAMA Resolution 357/2005 for Class 2 watercourses. Random generation of kinetic constants that regulate ammonia and nitrite decay produced significant ammonia nitrogen, nitrite, and nitrate peak concentrations value frequencies, histograms and forms changes, when considering variation percentages equal to or greater than 50%. Some simulation results showed more inhibition of oxidized nitrogen forms production. Keywords: monte carlo method, stochastic modeling, uncertainty analysis, water quality.

Wastes arising from human activities can reach water bodies and contribute significantly to the presence of antibiotic resistant bacterial populations in aquatic environments. The objective of this study was to evaluate the cultivable antibiotic resistant bacterial populations from a coastal lagoon impacted by agriculture and urbanization activities. Water samples were collected in low and peak season and characterized regarding physicochemical variables, microbiological indicators and the presence of antimicrobial residues. In order to analyze the presence of resistant bacterial populations, the samples were grown in the presence of nalidixic acid, ceftazidime, imipenem and tetracycline. Genes associated with β-lactamic resistance (blaCTX-M-like, blaGES-like, blaOXA-51, blaOXA-23-like, blaSHV-like, blaTEM-like and blaSPM-1), class I integron and efflux systems (tetA, tetB, acrA, acrB, tolC, adeA, adeB, adeR, adeS, mexB, mexD, mexF and mexY) were analyzed by conventional in vitro amplification. Although antimicrobials residues were below the detection limit, resistant bacteria and resistance determinants-blaGES, class I integron, adeS, acrA, acrB, tolC, mexB, mexF-were present at almost all points, in both seasons and for all antimicrobials assessed. The high numbers of resistant bacteria counts observed after the antibiotic treatment were positively correlated to the urbanization effects on the Lagoon. Some resistant populations were even higher in the low season samples, indicating the importance of a systematic evaluation of antibiotic resistance on water resources.