Formoso River Research Articles

Capacity and current use of the Formoso river watershed, bonito municipality, Mato Grosso do Sul, Brazil: conflicts and land use recommendations

The lack of planning and feasibility of controlling actions over land use and land cover lead to relationship problems between the support capacity that environmental systems present and their current use. The goal of this study is to figure out how much land can be used based on its natural and physical features and to find problems that come up because of the heavy use in the Formoso River watershed. It is one of the most recognized Brazilian watersheds, due to its turistic, karst, and environmental characteristics. The methodology consists in handling and generating data in a GIS environment by performing a synthesis map, as well as adopting geoprocessing criteria and techniques in the field to validate the collected data. The results indicate that the watershed presents large areas without conflicts due to its numerous conservation units. However, major conflicts are identified in other areas, affecting the balance and dynamics of the landscape and its water resources. Such conflicts arise because soybean crops advance in fragile and karst areas. The highest concentration of confit is only 1.61%, particularly near the Formoso River marsh. Therefore, the present work considers a methodology that assesses the capacity of use through a method that has produced a summary document that is applicable and compatible with the karst system.

CA-Markov prediction modeling for the assessment of land use/land cover change in two sub-basins of the Tocantins-Araguaia River Basin.

Due to the anthropogenic pressures of expansion areas for livestock and agricultural production in the Brazilian Cerrado, it is of paramount importance to understand the dynamics of land use/land cover (LULC) changes in this region. Thus, we investigated LULC changes in two sub-basins of the Tocantins-Araguaia River basin from 1997 to 2015 and consequently projected future changes for the timespan between 2030 and 2050. The Formoso sub-basin experienced significant expansion of agricultural and pasture areas, whereas the Sono sub-basin limited farmland expansion (more stable native vegetation) due to substantial protected areas, trends that were also observed for future projections (2030 and 2050). Pastureland in the Formoso sub-basin increased by 5.8%, while the Sono sub-basin saw significant gains in cultivated land, according to change detection analyses during the 1997-2015 period. High stability probabilities of no change (> 70%) for grassland areas in the Sono River sub-basin and pasturelands in the Formoso River sub-basin were computed. The CA-Markov model demonstrated a high consistency level with actual LULC classes for both sub-basins, as indicated by an overall Kappa coefficient above 0.8. Future projections for 2030 and 2050 show a substantial expansion of agriculture and pasture in both sub-basins, driven by specific factors such as soil organic carbon stocks, distance from rural settlements, and proximity to rivers. Short- and mid-term simulations indicate substantial expansion of agriculture and pasture in both basins, with potential adverse impacts on water erosion. Consequently, developing policies for soil management and sustainable land use planning is essential for agroecosystem sustainability, promoting a balanced approach to economic development while addressing climate change and anthropogenic challenges.

Agent-Based Modelling for representing water allocation methodologies in the irrigation system of the Formoso River Basin, Brazil

Agent-Based Modelling for representing water allocation methodologies in the irrigation system of the Formoso River Basin, Brazil

Avaliação de cenários de alocação coletiva de direitos à água utilizando o modelo de simulação WEAP em regiões de conflito pelo uso da água: o caso da Bacia do Rio Formoso-Tocantins/Brasil

ABSTRACT The aim of the present study was to carry out a hydrological simulation of the Formoso River basin using WEAP and to model scenarios based on the rotating rules of the water pump in regions of conflict for the use of water. During July 2020, the influence of such rules on the remaining flow in these regions was assessed considering a collective grant context in which minimum environmental flows, determined from the seasonal Q90 (flexible) and monthly Q95 (conservative), should be preserved downstream from the critical sections. The results showed that the remaining flow exceeded the limit of the flexible environmental flow in 61% of the days in the middle stretch of the Formoso River and at the mouth of the Urubu River. In the lower section and mouth of the Formoso River, these values were above the conservative limit in 93% and 100% of the days, respectively. It was concluded that the application of the rules, coupled with the collective grant, could produce satisfactory results for water availability in the basin.

Las unidades morfoestructurales de la cuenca hidrográfica del río Formoso, Bonito - Mato Grosso do Sul - Brasil: analizando un sistema cárstico

The morphostructural units of the Formoso River hydrographic basin (Bonito – Brazil) are unique in Brazil and configure the karst landscapes of Serra da Bodoquena. The present research aims to identify and spatialize the karst units inside a semi-detail scale and analyze their correlation with the regional landscape. Thus, the database is based on: 1) technical information offered by The Geological Survey of Brazil; 2) data offered by the Radam/Brasil Project; 3) altimetric charts of the study area; 4) field trip data to develop and verify the regional karst landscape. The authors observed a major presence of carbonated rocks in the study area (64.93%) and a minor but significant presence of terrigenous rock extension (35.07%). The main geological formations of the study area are the Cuiabá Group (terrigenous rocks) and Corumba Group (carbonated rocks). The regional landscape conditions of the Formoso River Hydrographic basin directly influence superficial water characteristics creating translucent water. The karst area presents classical characteristics with caves, mogotes, dolines, and river sinks. In addition, the area presents significant pedological variation and complexity that influence the local canopy cover with human activity all over the study area, affecting the landscape and threatening the karst scenario.

Linking multivariate statistical methods and water quality indices to evaluate the natural and anthropogenic geochemical processes controlling the water quality of a tropical watershed.

The improvement of water management requires monitoring techniques that accurately evaluate water quality status and detect the effects of land use changes on water chemistry. This study aimed to evaluate how multivariate statistical methods and water quality indices can be applied together to evaluate the processes controlling water chemical composition and the overall water quality status of a tropical watershed. Thirty-four water samples were collected in the Formoso River basin, located on the border of the Amazon Forest. Water parameters were measured in situ using a multiparameter and in the lab using spectroscopic and volumetric techniques. The water quality dataset was interpreted through principal component analysis, multivariate linear regression, and water quality indices. Statistical methods allowed us to identify the sources and geochemical processes controlling water quality chemistry, which were carbonate dissolution, runoff/erosion, nutrient input due to anthropogenic activities, and redox reactions in flooded zones. They were also used to create linear functions to evaluate the effects of land use changes on the geochemical processes controlling water chemistry. Conversely, the water quality indices provide information about the overall condition of the water. The Weight-Arithmetic Quality Index correctly evaluates water suitability for its multiple uses, according to the Brazilian guidelines. Conversely, the Ontario Water Quality Index is not suitable to evaluate the water quality of tropical rivers, since the usual higher water temperature and the low oxygen contents associated with tropical environments result in biased water quality evaluations by this index.

Sources of intraspecific variation in the isotopic niche of a semi-aquatic predator in a human-modified landscape.

Intraspecific variation modulates patterns of resource use by species, potentially affecting the structure and stability of food webs. In human-modified landscapes, habitat disturbance modifies trophic interactions and intraspecific niche variation, impacting population persistence. Here, we investigated the relationship of sex, ontogeny, and habitat factors with the trophic niche of Caiman crocodilus in an agricultural landscape. We evaluated temporal variation in the trophic niche parameters using carbon and nitrogen stable isotope analysis from different body tissues. We found that caimans exploit the same carbon and nitrogen pools through time, with low isotopic variability between seasons, partly due to the slow isotope turnover rates of tissues in crocodilians. Conversely, the trophic niche of caimans varied across habitats, but with no evidence of a difference between natural and anthropogenic habitats. It apparently results from the influence of habitat suitability, connectivity, and caiman movements during the foraging. Our findings highlight the broader niches of juvenile caimans relative to adults, possibly in response of territorialism and opportunistic foraging strategy. Although using similar resources, females had a larger niche than males, probably associated with foraging strategies during nesting. Considering the sex and body size categories, caimans occupied distinct isotopic regions in some habitats, indicating apparent niche segregation. Ontogenetic trophic shifts in the isotopes (δ13C and δ15N) depended on sex, leading to resource partitioning that can potentially reduce intraspecific competition. Decision-makers and stakeholders should consider the trophic dynamics of sex and body size groups for the sustainable management and conservation of caiman populations, which implies in the maintenance of wetland habitats and landscape heterogeneity in the Formoso River floodplain.

Spatial analysis of the soil erosion in the hydrographic basin of Formoso River: subsidy to politics of land use and environmental preservation in a region of Brazilian Cerrado

The erosion of the soil is one of the most worrisome environmental problems of the planet, which causes negative impacts as fertility loss of lands and water bodies pollution. The objective of this paper was to analyze the soil erosion in the hydrographic basin of Formoso River, located in the state of Goiás, Brazilian Cerrado. Most part of the hydrographic basin area belongs to the Emas National Park Conservation Unit. To estimate the soil loss from surface erosion, remote sensing products were used, geoprocessing tools and the Universal Soil Loss Equation (USLE). The annual erosion values in the basin varied from 0 t ha-1 year-1 to 8315 t ha-1 year-1, with 85.88% of the total area for soil losses classified in the slight category. The highest soil losses are associated with high results for R, K and LS factors in agricultural use, which represents 29.12% of the total area, with losses of 97.78% of soil from real erosion, in soils classified dystrophic Red Latosol, medium texture and high topographic values areas. The agricultural areas and the analysis of the real erosion reassures the necessity of proper planning, considering correct management techniques, in order to it won’t compromise the water resource. This study could subsidize the planning and management of the referred hydrographic basin and this important preservation area of the Cerrado.Keywords: Geoprocessing; Remote sensing; Cerrado; USLE; Emas National Park. Análise espacial da erosão do solo na bacia hidrográfica do Rio Formoso: subsídio à política de uso do solo e preservação ambiental em uma região do cerrado brasileiro R E S U M OA erosão do solo é um dos problemas ambientais mais preocupantes do planeta, que causa impactos negativos, como perda de fertilidade das terras e poluição dos corpos d'água. O objetivo deste trabalho foi analisar a erosão do solo na bacia hidrográfica do Rio Formoso, localizado no estado de Goiás, Cerrado brasileiro. A maior parte da área da bacia hidrográfica pertence à Unidade de Conservação do Parque Nacional das Emas. Para estimar a perda de solo por erosão superficial, foram utilizados produtos de sensoriamento remoto, ferramentas de geoprocessamento e a Equação Universal de Perda de Solo (USLE). Os valores de erosão anual na bacia variaram de 0 t ha-1 ano-1 a 8315 t ha-1 ano-1, com 85,88% da área total para perdas de solo classificadas na categoria leve. As maiores perdas de solo estão associadas a resultados elevados para os fatores R, K e LS no uso agrícola, que representa 29,12% da área total, com perdas de 97,78% de solo por erosão real. As áreas agrícolas e a análise da erosão real reafirmam a necessidade de planejamento adequado, considerando técnicas de manejo corretas.Palavras-chave: Geoprocessamento. Sensoriamento remoto. Cerrado. USLE. Parque Nacional das Emas.

Dieta de Moenkhausia bonita () (Characiformes: Characidae) em riachos da bacia do rio Formoso, Centro-Oeste brasileiro

Abstract To characterize the diet composition of Moenkhausia bonita and its temporal and ontogenetic variations in streams in the Formoso River basin (MS). The collections were carried out in seven sampling points in two periods throughout the year (dry and rainy). The food items were analyzed according to the volumetric and occurrence frequency methods and the diet was characterized through the Food Index (IAi%). To determine ontogeny, the specimens were divided into five size classes in the dry (D1 to D5) and rainy (R1 to R5) periods. To verify the difference between the species’ diet between the size classes and the periods of the year, the Permutational Multivariate Analysis of Variance – PERMANOVA analysis was performed. Moenkhausia bonita was classified as an invertivore when it consumed basically both aquatic and terrestrial invertebrates (99.5% of the diet), with higher consumption of aquatic invertebrates. There was a significant difference in the diet of between the dry and rainy periods, and although the species basically consumed the same items in the two studied periods, the proportions were different and there was no difference in the diet between size classes. M. bonita diet is based on autochthonous resources regardless of the size class, but that there were different consumption patterns when comparing the different periods of the year. The present study provided the first information on the feeding of M. bonita in a lotic environment and diet spectrum in the developmental phases, (ontogeny) and periods of the year, enabling a better understanding of the species, the importance of invertebrates in its diet, and the need for future studies on the biology, autoecology, and behavior of this species.

Landscapes of the Formoso river watershed, Mato Grosso do Sul - Brazil

The present research aims to identify, classify and map the landscape units of the Formoso River Watershed, located in the state of Mato Grosso do Sul - Brazil. The classification is based on geological, hypsometric, slope, horizontal dissection, vertical dissection, and erosive potential energy data of the relief. In addition to soil and land use data, as well as several theoretical and cartographic references that deal with the karst and non-karst environment. The study identifies seven first-order landscape units and 23 s-order units. The distinction between karst and terrigenous (non-karst) systems stands out in the units, and different features are observed in the landscape. In Serra da Bodoquena and in the areas of poljes, the landscapes result from the karst process on rocks. In the residual hills, on the flat surfaces and in the alluvial plains, the landscapes present their genesis associated with rocks of terrigenous origin. The duality highlights the uniqueness of the area. The study presents the complexity and heterogeneity of the landscape, and aims to contribute and expand the studies of karst environments, promoting preservationist and conservationist actions, as well as public policies in areas with similar characteristics in the State of Mato Grosso do Sul.

Analyzing the impact of agricultural water-demand management on water availability in the Urubu River basin – Tocantins, Brazil

The Urubu River is part of the Formoso River Basin located in Tocantins State in northern Brazil. It is an important agricultural region where irrigation has an important role in rice and soybean crops, cultivated during the rainy and the dry seasons, respectively. The high levels of irrigation associated with below-average precipitation in 2016 and in the following years resulted in a water crisis in the Urubu Basin, with serious consequences to the environment and the economy of the region. This work evaluated the impact of reducing irrigation on environmental flows in the Urubu River Basin using hydrological modeling in WEAP. Irrigation water demand scenarios were simulated and analyzed from July 2018 through June 2019. Results indicated the need to reduce 35% of all water withdrawls in order to avoid the interruption of flow in the Urubu River Basin. This percentage was even greater when only some of the farmers cooperated. The paper emphasized that it is important that all farmers be involved and cooperate to reduce their water withdrawal by any means, including improving their irrigation system efficiency. The water regulator may also motivate water withdrawal reduction by modifying water permits and applying water withdrawal restrictions during the dry season.
 Keywords: hydrological modeling, scenario analysis, water balance.

Pesticide residues in the Formoso River: a threat to biodiversity in the Cerrado of the Tocantins State, Brazil

Cerrado biodiversity has been threatened by the increase in agricultural production in the state of Tocantins and the increase in the use of pesticides. This work was carried out in the Formoso do Araguaia region, on the banks of the Formoso River, which is home to about 1,825 indigenous people and is one of the largest indigenous lands in the state of Tocantins, Brazil. The presence of pesticides of the imidazolinone and strobirulin classes was verified, analyzed by UHPLC-MS/MS from April 2018 to February 2019, to assess the impacts of these pesticides on the biodiversity of the study site. After the analyses, five active principles (azoxystrobin, phenamidone, imazethapyr, tricyclazole and trifloxystrobin) were detected in the water matrix, two active principles (azoxystrobin and tricyclazole) in the soil matrix, but no active principle was detected in the sediment matrix. Contamination in the region, where riverine and indigenous people use this water for cultivation, hygiene and food, which is worrying, are exposed to these substances.

Production of Irrigated Rice in the Second Stage of the River Formoso Project in the Brazilian Savanna Region

The information survey was carried out in the second stage of the Formoso River Project in Formoso do Araguaia - TO, in the COPERJAVA area - Mixed Cooperative Rural Valley of Javaés Ltda, located in the Brazilian savanna region. During the research period, some practices related to the production of irrigated rice were monitored, such as straw burning, soil preparation, sowing, nitrogen fertilization cover, and phytosanitary treatments to control weeds, insect pests, and diseases. Monitoring was made in the cultivated areas to observe the development of irrigated rice, and to regulate the height of the water depth in the plots and its uniformities of the water depth. Activities were developed to regulate equipment and facilities involved in rice production. These provided an increase in the knowledge acquired about the irrigated rice crop, emphasizing the need and importance of the association between the theoretical basis acquired during the course and the practice in the field.

Geoecological diagnosis of landscapes of the Formoso River Watershed, Bonito/MS, Brazil

Geoecological diagnosis of landscapes of the Formoso River Watershed, Bonito/MS, Brazil

Assessment of the trophic status in a tropical estuarine system

Estuaries are extremely valuable ecosystems and have been affected by several anthropogenic activities from urban growth and industrial development, such as the release of untreated efuents which decrease water quality. This study aimed to evaluate the seasonal and temporal trophic status variation in the Formoso River Estuarine System (FRES), a tropical estuary. Three campaigns were carried out in each season (rainy and dry), during which surface water was sampled for abiotic parameter analyses. The TRIX index was used for trophic status assessment. For the temporal evaluation, a review of literature addressing the matter in the study area was conducted. Between 2017 and 2018, the TRIX index varied from a mean of 6 ± 0.2 upstream to 5 ± 0.4 downstream during the rainy season, indicating eutrophic conditions throughout most of the FRES extension, especially near the Formoso River, and from 6 ± 1 to 3 ± 0.8 during the dry season. Temporal analyses showed that in 2002 the overall mean TRIX index was 5.72 ± 0.4, decreasing in 2005 and 2014, and followed by an upwards trend. We conclude that the FRES is impacted by the release of untreated efuents such as sewage and fertilizers from the city of Rio Formoso and from various agricultural activities, which are more intense during the rainy season. Nevertheless, over time there were more critical scenarios pertaining to the trophic status. The present diagnosis reinforces the importance of public sanitation policies in estuarine regions and spatial planning instruments for pollution control in fishery areas.

Mapping the Available Water Capacity in tropical climate soils for soybean (Glycine max) cultivation in the state of Tocantins-Brazil

Brazilian soybean has undergone considerable economic growth. Its production depends on the demand for some inputs. One of these inputs is the soil water supply, which can be made artificially or obtained by natural rainfall. Knowledge of available water capacity (AWC), which depends on total water availability (TWA), is poorly accessible and difficult to measure in the field. This study aimed to map the AWC of the state of Tocantins, based on pedotransfer functions (PTFs), to evaluate the water availability of the soils of the microregions of that state. We used the Arya and Paris model, aided by a computer program, Qualisolo, made by Embrapa Instrumentação. One hundred fifty-seven tropical soil samples were extracted from the Embrapa Solos portal. Preliminarily, the soil water retention curve (SWRC) was obtained and, subsequently, the TWA and AWC for this oilseed were estimated. Multiple linear regressions show the correlation between TWA and clay (CL), Silt (ST) and total sand (TS) contents. The correlation established was TWA = 3.2993 – 0.0028TS – 0.0034CL. This main conclusion reflects a fruitful AWC for decision-making by the soybean agribusiness and exposes the regional weaknesses for this crop under a rainfed regime in some regions of Tocantins. We could observe that, in terms of water availability, agribusiness is a potential threat to the environment protection area (APA) of the Ilha do Bananal/Cantão, Formoso River microregion.

Incorporating costs, thresholds and spatial extents for selecting stream bioindicators in an ecotone between two Brazilian biodiversity hotspots

Biomonitoring is critical for characterizing and monitoring status, spatial patterns, and long-term trends in the ecological condition of freshwater ecosystems. The selection of cost-effective bioindicators is a critical step in establishing such monitoring programs. Key indicator considerations are a reliable response to anthropogenic disturbances, a high benefit-cost-ratio and sensitivity at multiple spatial extents. We evaluated non-linear responses of Ephemeroptera, Plecoptera and Trichoptera (EPT) and fish to the effects of native vegetation loss within buffers of 100 m and 1000 m and assessed the sampling and processing costs involved for each assemblage. We sampled 37 neotropical stream sites in the Formoso River network, a karstic region of the Bodoquena Plateau, midwest Brazil, lying in the ecotone between the Cerrado and Atlantic Forest biological hotspots. We used TITAN (threshold indicator taxa analysis) to identify six indicator taxa, four EPT genera and two fish species. The four EPT genera had low negative thresholds to native vegetation loss, whereas the two fish species had positive thresholds. Thresholds were lower for the 100 m buffers than the 1000 m buffers for EPT. The most sensitive taxon (Macronema, Trichoptera) had a threshold of 0% native vegetation loss in the 100 m buffers and nearly 40% in the 1000 m buffers. For taxa richness, we found no non-linear response to the effects of native vegetation loss for buffer extent nor assemblage. The total cost for EPT biomonitoring was US$ 3,616; whereas for fish, the total was US$ 1,901. Although fish were less expensive than EPT, they did not respond negatively to native vegetation loss and their positive threshold started at 48%, a level of vegetation loss that was highly disruptive of EPT. Therefore, we do not recommend using fish to monitor the effects of native vegetation loss on headwater streams in the Bodoquena Plateau. Although EPT monitoring costs 52% more than fish assemblage monitoring, it detected earlier impacts of the effects of native vegetation loss on stream biota, especially in the 100 m buffer. Therefore, EPT are more cost-effective early warning indicators for monitoring the effects of native vegetation loss in Bodoquena Plateau headwaters.

Morphological sexual maturity by relative growth technique of Uca maracoani (Brachyura, Ocypodidae) from a tropical mangrove

Despite of the existence of previous knowledge on the relative growth of U. maracoani for a population of southeastern Brazilian coast, the aim of the study was described and compare the relative growth patterns and sexual maturity of this species from Formoso River mangrove, state of Pernambuco, northeast Brazil, with data from other locations and of congeneric species. The crabs were monthly sampled manually, with a capture effort by one person colleting for 30 minutes at the low tide from April 2009 to March 2010. Crabs of both sexes were measured with a caliper at following dimensions: carapace width (CW), carapace length (CL), cheliped propodus length (CPL), cheliped propodus height (CPH) and abdomen width (AW). Additionally, males were also measured at their gonopod length (GL). The determination of morphological maturity was based on the relationship between the CPL vs. CW for males and AW vs. CW for females, which were the relations that best evidenced the beginning of the morphological sexual maturity for U. maracoani. The relationships CPL vs. CW and AW vs. CW evidenced positive allometry for juveniles and adult’s males and females. However, a negative allometry was observed in the relationship CL vs. CW and GL vs. CW for juveniles and adult’s males, AW vs. CW for adults’ males and, CPH vs. CW for adults’ females. The growth pattern shown by the female abdomen probably is related to egg incubation and the excessive growth observed at the male cheliped is probably related to reproductive process, because this appendage is used at the courtship and intra or inter specific agonistic interactions with other males. The morphological sexual maturity of males was estimated at 15.8 mm CW (50% of males), with the smallest mature male measuring 17.34 mm, and the largest immature male 18.15 mm CW. Females reached morphological sexual maturity (50%) at 13.8 mm CW, with the smallest mature female at 15.43 mm CW and the largest immature female at 16.32 mm CW. The differential growth patterns between juvenile and adult phases, as well as the onset sexual maturity seem to have relationship with ontogenetic changes, which is mainly related to behavioral or reproductive traits. The growth pattern observed in the female's abdomen is probably related to hatching eggs while overgrowth shown in male cheliped should be related to reproductive processes, as this appendix is used in court and in specific interactions with other males.

Monitoring the water quality Formoso river of the Amazon Region – Brazil using principal component analysis

The expansion of the agricultural frontier poses a major threat to the quality of water bodies and conservation and biodiversity of biomes. In the Tocantins-Araguaia, hydrographic region is located the largest irrigated flood type rice project in the world, and in the inter-harvest period, the area is still used for soybean production. Considering the great economic, environmental and social importance of the area, the objective of this study was to evaluate the water quality Considering the great economic, environmental and social importance of the area, the objective of this study was to evaluate the water quality of a river in the Amazon Region, Brazil, and to identify the critical pollution sites in the area of influence of the agricultural project. The monitoring occurred between April 2018 and February 2019, during periods of drought and drought. The water quality was evaluated based on the determination of 34 physical-chemical and 2 microbiological parameters. The comparison of the values obtained with the limits allowed by the legislation for class II waters pointed out samples with high total phosphorus values, which can lead to eutrophication phenomena, concentrations above the expected of metals such as Fe, Cu, and Mn and samples with low percentage of dissolved oxygen. The main component analysis (PCA) showed little variation along the river, i.e., homogeneity in the different points evaluated in the same collection; however, the comparison between collections with different seasonalities revealed quite divergent results, reinforcing that seasonal variations can aggravate the changes in the water quality of the river.

Biliary polycyclic aromatic hydrocarbons and enzymatic biomarkers in Eugerres brasilianus along four tropical estuaries

Polycyclic aromatic hydrocarbons (PAH) in bile and biochemical biomarkers were evaluated in Brazilian mojarra Eugerres brasilianus along four estuaries in northeastern Brazil. Bile PAHs naphthalene, phenanthrene chrysene, pyrene and benzo[a]pyrene were lowest at Formoso River Estuarine System (FRES), an area with low population density focused on tourism. Fish sampled in Suape Estuarine Complex (SEC), where a growing industrial port complex is established indicated higher naphthalene and pyrene concentrations compared with FRES. Fish sampled in highly urbanized and populated Bacia do Pina Estuarine Complex (BPEC) and Barra de Jangada Estuarine System (BJES) indicated an increase in all PAHs compared to FRES. Activities of phase 1 Ethoxyresorufin-O-deethylase, phase 2 glutathione-S-transferase and antioxidant defense catalase were induced up to 20, 2 and 2-fold in BJES and BPEC compared to FRES. This study confirms E. brasilianus as an important sentinel species, providing baseline information for these tropical estuaries with different degrees of anthropogenic pressure.