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Bioecologia de Ucides cordatus Linnaeus 1763 (Decapoda: Ocypodidade) em áreas com diferentes níveis de impactos antrópicos no Golfão Maranhense, Brasil

Tue, 15 Mar 2022 00:00:00 GMT

Título: Bioecologia de Ucides cordatus Linnaeus 1763 (Decapoda: Ocypodidade) em áreas com diferentes níveis de impactos antrópicos no Golfão Maranhense, Brasil Abstact: Bioecology studies that address reproduction and morphometry have accurate information to assist in the conservation of species. This study aimed to analyze the bioecology of Ucides cordatus in two areas with different levels of human impacts in the Maranhense Gulf, involving morphological and reproductive aspects and population structure. The first area is the Manguezal do Zé da Mata (less anthropogenically impacted) located in the municipality of Raposa and the second is the Porto Grande Manguezal (with the greatest human impact), located in the municipality of São Luís. Six collections were carried out in the period from September 2020 to December 2021. Population density was measured by counting the number of galleries in five 1m² quadrants along a 35m transect in all sampling months and calculated in G/m². Biometric data from specimens were compared between sampling sites using Student's t test; the population density data were correlated with the abiotic data pH, temperature and dissolved oxygen through a multiple regression and finally, the size at first sexual maturation (L50) was verified. The immediate (PEI) and future (PEF) extractive potential were evaluated based on the Carapace Width (LC mm) with the PEI: LC =/> 60mm and the PEF: LC =/< 60mm. In addition, sediment samples from the sampling areas were analyzed to identify the difference between the levels of anthropic impact. The abiotic data did not influence the population density of the species in the two analyzed sites. There was a significant difference between the means of LC (mm) and CC (mm) between the specimens from Zé da Mata and Porto Grande, with more robust individuals in the latter. The immediate extractive potential (PEI) was higher in the Porto Grande mangrove, as were the values of G/m² (4.93). The L50 was 51.33 mm for the mangrove of Zé da Mata and 54.42 mm for the mangrove of Porto Grande, demonstrating that the population of these places can reproduce at least once before reaching their commercial size (60 mm of LC) . The results on crabs from the two mangroves indicate stable populations, although there is greater fishing pressure in the Zé da Mata mangrove. These data point to the need for inspection of fishing activity and guidance for the Raposa community, especially regarding the closed season for the species.

Viabilidade do uso de espermatozoides criopreservados de Colossoma macropomum, (CUVIER, 1816) expostos a Cipermetrina

Mon, 01 Jan 2024 00:00:00 GMT

Título: Viabilidade do uso de espermatozoides criopreservados de Colossoma macropomum, (CUVIER, 1816) expostos a Cipermetrina Abstact: Cypermethrin is a pesticide compound widely used to combat insects in agricultural and domestic environments, but its indiscriminate use and inadequate disposal of packaging can cause adverse effects on animals living in directly or indirectly affected environments. This work aimed to analyze the feasibility of using atabaque (Colossoma macropomum) sperm in ecotoxicological bioassays with cypermethrin. Seminal samples from sexually mature Tamaqua males were used. Fresh semen was collected eight hours after hormonal induction in graduated glass tubes. After an initial assessment of the absence of prior activation, the experiment was carried out in a factorial scheme, testing five concentrations of cypermethrin (2.5; 25; 125; 250 and 500 mg/L), where motility was evaluated by the subjective method and the data expressed in percentage of motile cells in samples per time in seconds. The lethal dose (LD50) was evaluated from the activation of the gametes until the motility regressed to 50% in the samples; total activity time was recorded to within 10% of motile cells (in seconds) after their initial activation. As a control, activation with 0.9% NaCl solution and motility analysis were used in the same way as described for cypermethrin. In the cryopreservation stage, cryoprotective solutions were prepared, with concentrations of 75% glucose, 10% DMSO, 5% egg yolk. The semen was then placed in microstrips and stored in a dryshipper with nitrogen for up to 20 minutes. After temperature stabilization, the samples were transferred to liquid nitrogen at a temperature of -196°C. For thawing, the samples were removed from liquid nitrogen and placed in a water bath at 60°C for 8 seconds, transferred to plastic tubes and analyzed. Semen analyzes were carried out under an optical microscope and sperm viability was assessed through activation with NaCl solution. After confirming viability through sperm characterization analysis, the samples were activated by cypermethrin concentrations and the subjective motility rate and motility time were established in triplicates, taking into account the Lethal Dose (LD50) for each repetition. Results indicate that in natura samples based on the subjective method presented an average duration of 118±12 seconds (considering up to 10% of sperm motility) and 95±5% according to the percentage of motile cells. The reduction in sperm motility occurred significantly (p<0.05), mainly at the cypermethrin concentration of 500 mg/L. In thawed samples, the average time was 46.9±10 seconds and the motility rate was 73.9±6% for motile cells. The reduction in motility was more intense from the 125mg/L concentration onwards, indicating the cellular limit of tolerance to the insecticide. The tests carried out demonstrate that tambaqui semen is sensitive to the process of exposure to cypermethrin residues and can be used in ecotoxicological bioassays.

Biomarcadores em brânquias e Hepatopâncreas de Ucides Cordatus Linnaeus (1873) (crustacea: decapoda) para o monitoramento de impactos antrópicos na ilha de São luís, Maranhão, Brasil

Thu, 10 Mar 2022 00:00:00 GMT

Título: Biomarcadores em brânquias e Hepatopâncreas de Ucides Cordatus Linnaeus (1873) (crustacea: decapoda) para o monitoramento de impactos antrópicos na ilha de São luís, Maranhão, Brasil Abstact: Biomonitoring studies with biomonitor species suitable for the analysis of histological biomarkers (in organs such as gills and hepatopancreas) have been considered important in the assessment of impacted environments. Thus, this study aimed to evaluate lesions in gills and hepatopancreas of Ucides cordatus, as indicative of anthropic impacts on São Luís Island, Maranhão. Crabs were collected by the braceamento technique with the help of a professional collector in two areas, one in São José Bay: Raposa (with less impact) and Porto Grande Baía de São Marcos (potentially impacted area). In the laboratory, the biometric data of each crab specimen were obtained and the specimens were dissected to remove and fix the gills and hepatopancreas in Davidson's solution for 24 hours. Tissue samples were submitted to the standard histological technique, where they were dehydrated in increasing series of alcohols, diaphanized in xylene, impregnated and embedded in paraffin. Then, 5 micrometer-thick cross-sections were stained with Hematoxylin and Eosin and the slides were analyzed under a light microscope. The biometric data of the crabs in the two areas were expressed as means and standard deviation. The data showed significant gill and liver lesions in crabs from both areas. The main lesions found for the gills were rupture of the pilaster cells; deformation of the marginal channel and necrosis in both rainy and dry seasons. The most observed liver lesions were lumen deformation, vacuolated B cells, pyknotic nuclei and necrosis, also in both seasons. The averages of carapace width and length show that crabs from Raposa (less impacted area) were smaller than crabs from potentially impacted area, in both seasonal periods, however, they also did not show significant differences between them (p>0.05). The Bray-Curtis index for the gill alterations of U. cordatus for the dry and rainy season showed for both regions a grouping greater than 0.9 (or 90%) of lesions such as rupture of pilaster cells and deformation of the marginal canal; the necrosis lesion was grouped hierarchically forming the set of “most frequent lesions”. For liver lesions, it was found that the data for crabs from the Raposa region show similarity (>80%) in the dry season and (>70%) for the rainy season, gathering the lesions pyknotic nuclei, vacuolated B cells, lumen and necrosis; for the Porto Grande region, the cluster indicated a grouping (>80%) for both seasonal periods, bringing together necrosis lesions, lumen deformation, vacuolated B cells and pyknotic nuclei showing these lesions in both regions as the set of lesions more frequently. The altered biological responses (gill and liver changes in U. cordatus) prove that these crabs are subjected to stress levels that are compromising the crabs' vital functions

Identificação molecular de espécies do gênero cichla (cichliformes: Cichlidae) Introduzidas em bacias hidrográficas maranhenses

Wed, 30 Mar 2022 00:00:00 GMT

Título: Identificação molecular de espécies do gênero cichla (cichliformes: Cichlidae) Introduzidas em bacias hidrográficas maranhenses Abstact: The inference on the origin of fish stocks introduced outside their habitat with a phylogenetic approach constitutes an important step in understanding and controlling the expansion of invasive species. In this sense, we used the DNA barcoding technique to identify species of the genus Cichla in Maranhão basins. The fish were collected in the Mearim/tributaries, Pindaré, Parnaíba and Tocantins basins, using nets of gillnets and nets, and then transported to the Laboratory of Genetics and Molecular Biology (GENBIMOL) for sorting and identification with the aid of specific literature and submitted to DNA extraction techniques, COI gene amplification via PCR and sequencing. Editing, sequence alignment, genetic distances, haplotype network were performed using the BioEdit, MEGA X and Network programs. ABGD, ASAP GYMC and PTP models were used for OTU delimitation. A total of 78 sequences of the COI gene were obtained, 37 sequences correspond to the species Cichla kelberi from the Pindaré River, Cichla monoculus from the Flores River, Cichla piquiti from the Tocantins River and Cichla sp. from the Parnaíba river and 41 sequences were from Genbank, with average intraspecific genetic divergence of 0% and interspecific genetic divergence from 6.78% to 44.75%. The clusters by phylogenetic reconstructions of (ML) and (BI) showed strongly supported clades, indicating agreement with the species assigned by morphological identification. A total of six haplotypes were obtained for specimens of the genus Cichla, with haplotypic diversity values h= 0.726 and nucleotide diversity π= 0.0479. The H1 haplotype was shared in populations of C. monoculus from the Parnaíba, Mearim and Alto Paraná rivers. The H2 haplotype shared populations of C. kelberi from the Pindaré, Tocantins and Alto Paraná rivers. The H3 haplotype was shared with populations of C. piquiti from the Tocantins and Paraná rivers. Three exclusive haplotypes were observed for the populations of Cichla ocellaris from the Maroni River in French Guiana, for Cichla melaniae and Cichla mirianae from the Xingú (H4, H5 and H6). The identification performed on the BOLD Systems platform confirmed the morphological identification of the species under study with a similarity of 99.13 to 100%. Therefore, we suggest that specimens of C. kelberi from the Pindaré River come from native populations from the Tocantins River basin and C. monoculus from the Mearim, Parnaíba and Alto Paraná Rivers, as they constitute the same haplotype, come from the same stock. It is also possible to infer that C. piquiti from the Paraná River is derived from populations from the Tocantins River. In conclusion, our study was the first to use molecular analysis to validate the presence of C. monoculus as an invasive species in Maranhão rivers, as well as confirming the introduction and registration of C. kelberi in the Pindaré River