DSpace Coleção:

Monitoramento ambiental do médio rio Tocantins: elementos potencialmente tóxicos e essenciais em água, sedimentos e peixes, biomarcadores e implicações para a saúde ribeirinha

Mon, 30 Mar 2026 00:00:00 GMT

Título: Monitoramento ambiental do médio rio Tocantins: elementos potencialmente tóxicos e essenciais em água, sedimentos e peixes, biomarcadores e implicações para a saúde ribeirinha Abstact: The Tocantins–Araguaia basin is one of the largest hydrographic systems in South America, spanning the states of Maranhão, Tocantins, and Pará, and is part of the Brazilian Legal Amazon. Despite draining extensive Cerrado and tropical forest ecosystems, this basin has undergone significant environmental degradation in recent decades due to agricultural expansion, deforestation, and the introduction of non-native species. This scenario is particularly relevant for riverine communities along the middle Tocantins River, which depend on the river for water supply, recreation, and fish consumption. In this context, fish can act as biomonitors of contaminant exposure in aquatic environments, as they integrate ecological processes and represent an important food and economic resource. Thus, the aim of this study was to perform environmental monitoring of the middle Tocantins River through an integrated approach, including the analysis of physicochemical water parameters, the determination of potentially toxic and essential elements in water, sediments, and fish, and the assessment of enzymatic biomarkers in native fish species. Sampling was conducted at four sites: P1 (Beira Rio – urban area), P2 (Bananal village), P3 (Embiral village), and P4 (Cidelândia village). The thesis is structured into five chapters. Chapter 1 presents a literature review on the Tocantins–Araguaia basin and ecotoxicological aspects related to contaminants in aquatic environments. Chapter 2 describes a socio-environmental study assessing riverine perceptions of water quality through structured questionnaires. The results showed that 34% of respondents consume and commercialize native fish, 62% use them for subsistence consumption, and 4% do not consume fish. Additionally, 84% reported the absence of sewage systems, highlighting high dependence on water and fish resources and significant socio-environmental vulnerability. Chapter 3 evaluated potentially toxic and essential elements in water, along with physicochemical parameters. Aluminum, copper, iron, magnesium, and selenium exceeded regulatory limits at certain sites and periods, with seasonal variations influenced by climatic factors. Site P1 exhibited higher electrical conductivity, total dissolved solids, chlorophyll, and nitrogen compounds, indicating anthropogenic influence and potential risks associated with untreated water consumption. In Chapter 4, sediment analysis revealed elevated concentrations of aluminum, iron, manganese, and selenium, as well as chromium, nickel, copper, zinc, and lead exceeding quality guidelines, particularly in areas influenced by urban activities. Higher concentrations during the rainy season highlighted the role of seasonality in contaminant mobilization and deposition processes. Chapter 5 investigated the bioaccumulation of potentially toxic and essential elements and enzymatic responses in native fish species (Psectrogaster amazonica and Caenotropus labyrhinthicus). Elevated concentrations of arsenic, lead, and selenium were detected in fish tissues, exceeding recommended limits. Enzymatic activities (AChE, AST, ALT, and ALP) indicated physiological responses associated with environmental exposure and were interpreted as sublethal alterations, without allowing direct inference of causality or specific mechanisms. Overall, the results indicate that the dynamics of elements in the middle Tocantins River are controlled by the interaction between natural processes and anthropogenic influences. The concentrations of elements such as iron, aluminum, and manganese partly reflect the regional geochemical background, characterized by highly weathered tropical soils, while physicochemical parameters and spatial patterns indicate the influence of human activities, particularly in urban areas. The observed bioaccumulation in fish and enzymatic responses indicate organism exposure to environmental contaminants and associated physiological alterations. These findings, combined with the strong dependence of riverine populations on water and fish resources, highlight the importance of integrated environmental monitoring approaches that consider regional specificities and their implications for environmental health and food safety, in line with the One Health framework

Biologia reprodutiva e ecologia trófica de Conodon nobilis (linnaeus, 1758) e Bagre bagre (linnaeus, 1766) capturados no golfão maranhense – Brasil

Sun, 16 Jun 2024 00:00:00 GMT

Título: Biologia reprodutiva e ecologia trófica de Conodon nobilis (linnaeus, 1758) e Bagre bagre (linnaeus, 1766) capturados no golfão maranhense – Brasil Abstact: Knowledge of fish biology provides data for the correct management of fishing resources, enabling the formulation of conservation measures and fishing management. Considering existing gaps in the explored ichthyofauna, this research aimed to analyze the reproductive biology and trophic ecology of Conodon nobilis (Linnaeus, 1758) and Bagre bagre (Linnaeus, 1766) from artisanal fishing captured in the fishing community of Raposa, located in the Gulf Maranhão. 360 specimens were acquired for each species, between January and December 2021. In the laboratory, the biometric data of each specimen were recorded and then they were sectioned to remove the tissues, stomach and gonad. The gonadosomatic index (IGS), condition factor (K), sex ratio, type of spawning and spawning season were evaluated. Stomach contents were conditioned and preserved in 10% formaldehyde for analysis, identification and classification of food items at the lowest possible taxonomic level. The degree of repellency and feeding strategies of each species were analyzed. For C. nobilis the length ranged from 11 to 31.8 cm. The sex ratio was 1 Male:1.51 Female and negative allometric growth (b<3). Five stages of gonadal maturation were confirmed throughout the sampling period, for both species, namely: Immature phase (IM); Development phase (DP); Spawning capacity phase (SP); Regression phase (RP); Regeneration phase (RGP). The length of first sexual maturity (L50) for males was 18.94cm, for females it was 18.91cm and for the grouped sexes it was 18.92cm and according to the gonadosomatic indices, individuals in spawning capacity were found in the months of January, April, May, July, September and December, indicating which species has split spawning. This species adopts a generalist feeding strategy, with greater consumption of fish and crustaceans. However, due to the predominance of fish in the diet, C. nobilis can be characterized as a species with a carnivorous eating habit and a piscivorous tendency. For the Bagre bagre species, the length varied between 22.08 and 57.6 cm. The sex ratio found was 1 Male:1.29 Females and negative allometric growth (b<3). The length of first sexual maturity (L50) for males was 33.51cm, for females it was 29.40cm and for the grouped sexes it was 31.21cm and the highest gonadosomatic peaks in females were recorded in the months of January and August to December, while for males these peaks varied in the months of January, May, August and December, indicating split spawning. B. catfish demonstrates a generalist, predominantly carnivorous feeding strategy, with a preference for fish. Given this information, it is possible to define closed periods, minimum catch size, in addition to evaluating the impact of fishing on food chains with a view to proposing measures that minimize disturbances in ecosystems and help preserve fish populations at sustainable levels.

Caracterização clínica, cito-histomorfológica e molecular da esporotricose felina na Ilha de São Luís-MA

Mon, 17 Jun 2024 00:00:00 GMT

Título: Caracterização clínica, cito-histomorfológica e molecular da esporotricose felina na Ilha de São Luís-MA Abstact: Sporotrichosis is a zoonotic cutaneous mycosis caused by saprophytic fungi of the genus Sporothrix spp. which affects cats, armadillos, horses, dogs and humans. In urban areas, cats are the main transmitters of the disease to humans, through bites and scratches. The clinical forms of the disease are: fixed cutaneous, disseminated cutaneous, extracutaneous and lymphocutaneous. The aim of this study was to carry out the clinical, phenotypic and molecular characterization of sporotrichosis in cats living on the island of São Luís, in the state of Maranhão. From October 2022 to July 2023, clinical assessments and cytological examinations were carried out on cats suspected of having sporotrichosis seen at the Francisco Edilberto Uchôa Lopes Veterinary Hospital of the State University of Maranhão. Felines with lesions suggestive of sporotrichosis were selected, without criteria of breed, sex, age or reproductive status. Exudate from the lesions was collected for fungal culture and cytological examination. The positive samples were isolated and sent for phenotypic and molecular identification of the fungal genus. A total of 46 animals were selected: 33 males and 13 females. The disseminated cutaneous clinical form was observed in 70% of the cats evaluated. The regions of the body with the most lesions were the face, ears, back of the thoracic region and limbs. In the fungal culture, white colonies were observed, which progressively became blackish and had a leathery texture compatible with the species Sporothrix spp. The micromorphological analysis showed hyaline hyphae with round conidia and daisy-like conidiophores. The samples that tested positive in the micromorphological evaluation were sent for molecular analysis. PCR was carried out using primers specific to the S. brasiliensis species. All 46 samples successfully amplified the CAL gene. Five samples were selected for phylogenetic analysis. The BLASTn analysis found isolates with percentages of genetic identity ranging from 90 to 100% with sequences of S. brasiliensis (cal gene), previously deposited in the genbank of isolates from different hosts and locations, such as felines, dogs and humans. S. brasiliensis is responsible for causing disease in felines living on the island of São Luís - MA.

Detecção de parasitas do gênero Trypanosoma em pequenos ruminantes no norte maranhense, Brasil

Mon, 09 Jun 2025 00:00:00 GMT

Título: Detecção de parasitas do gênero Trypanosoma em pequenos ruminantes no norte maranhense, Brasil Abstact: Animal trypanosomiasis represents a significant sanitary and economic challenge for tropical livestock production, causing severe anemia and systemic inflammation in ruminants. In Brazil, Trypanosoma vivax is the most clinically relevant species in goats and sheep, associated with high morbidity, mortality, and production losses, though infections may also occur asymptomatically. While T. evansi and T. theileri can infect small ruminants, their pathogenicity in these hosts is considered low. In Maranhão state, the complete absence of studies on trypanosomiasis in small ruminants represents a critical epidemiological gap, leaving herds vulnerable to undiagnosed outbreaks. This study aimed to detect Trypanosoma spp. in small ruminants across Maranhão using direct and indirect diagnostic methods. Blood samples were collected from 84 goats and 210 sheep across 14 farms in São Bento, Pinheiro, and Itapecuru-Mirim municipalities during both dry and rainy seasons. A structured questionnaire documented risk factors, and individual animal records included demographic and health data. Diagnostic approaches included direct microscopy of blood smears, indirect ELISA for anti-T. vivax antibodies, species-specific PCR targeting T. vivax, T. evansi, and T. theileri genomic fragments, sequencing and phylogenetic analysis of PCR-positive samples (BLAST against GenBank), and statistical analysis using Chi-square and Fisher's exact tests for risk factors. No trypanosomes were detected by microscopy. Seroprevalence reached 14.28% (42/294), with 30 (10.20%) goats and 12 (4.08%) sheep testing positive. Two samples (0.68%) were PCR-positive for T. vivax, showing 100% identity with Brazilian isolates from buffaloes, cattle, small ruminants, and donkeys in GenBank. Phylogenetic analysis confirmed homology with these T. vivax strains. All samples tested negative for T. evansi and T. theileri. Significant risk factors (p<0.05) included host species (higher in goats), recent animal acquisitions, veterinary care availability, farm infrastructure quality, and housing type. This study provides the first molecular evidence of T. vivax infection in Maranhão's small ruminants, highlighting the need for control measures. The findings expand understanding of animal trypanosomiasis in Brazil and underscore the vulnerability of small ruminant production systems to this neglected disease.