Resumo Neste estudo objetivou-se analisar os aspectos reprodutivos (período estacional e quantidade de embriões) e a positividade para S. mansoni em roedores do gênero Holochilus, no município de São Bento - MA. Para isso, foram realizadas capturas mensais de até 10 roedores Holochilus sp., aleatoriamente quanto ao sexo, anotando-se o período estacional do município de São Bento nos meses de captura. Em laboratório, os roedores tiveram as fezes analisadas quanto à positividade para S. mansoni pelo método Kato-Katz. Após a análise, os animais foram anestesiados para a obtenção do comprimento total, peso corporal e determinação do sexo. Nas fêmeas, foi realizada a incisão da porção ventral do corpo, para a verificação da presença de embriões e contagem dos mesmos. Dentre os roedores capturados, ocorreu dominância de machos em quase todos os meses e eles tenderam a ser mais pesados e apresentaram maior porte que as fêmeas. Os animais mostraram elevado potencial reprodutivo. A positividade para S. mansoni e a reprodução dos Holochilus sp. foram maiores no período chuvoso de São Bento. Quanto ao número de embriões, constatou-se que, no período chuvoso, foram encontrados em maior quantidade por fêmea. Em suma, a intensa atividade reprodutiva juntamente à suscetibilidade para S. mansoni apresentada pelos roedores são fatores que ajudam na manutenção e agravam a esquistossomose na Baixada Maranhense.
On the latest 60 years the degradation and fragmentation of native habitats have been modifying the landscape in the eastern Brazilian Amazon. The adaptive plasticity of an organism has been crucial for its long-term survival and success in these novel ecosystems. In this study, we investigated the response of four endangered species of large terrestrial mammals to the variations in the quality of their original habitats, in a context of high anthropogenic pressure. The distribution of the Myrmecophaga tridactyla (Giant anteater), Priodontes maximus (Giant armadillo), Tapirus terrestris (Lowland tapir) and Tayassu pecari (White-lipped peccary) in all sampled habitats suggests their tolerance to degradation. However, the survival ability of each species in the different habitats was not the same. Among the four species, T. pecari seems to be the one with the least ability to survive in more altered environments. The positive influence of the anthropogenically altered habitats on abundances of three of the four species studied, as observed at the regeneration areas, can be considered as a potential indication of the ecological trap phenomenon. This study reinforces the importance of the forest remnants for the survival of endangered mammal species, in regions of high anthropogenic pressure, as in the eastern Brazilian Amazon.
In recent years, increasing economic development has resulted in high rates of change in land use which have a negative impact on both terrestrial and aquatic habitats (Newbold et al., 2018). In the Amazon region, many studies have demonstrated that these changes in land use have resulted in a decrease in the basal area of the forest, changes in the physical-chemical characteristics of the water, such as its temperature and pH, the loss of riparian vegetation and impacts on the associated fauna (Luiza-Andrade et al., 2017;Mendes-Oliveira et al., 2017;Prudente et al., 2017). Nepstad et al. (2008) found that approximately 20% of the forest in the Amazon region has already been transformed
The South American silver croaker it's a specie of great importance for the fishing profitability of Maranhão state, being the target of most of the fisheries of the Environmental Protection Area of Baixada Maranhense. The present work aimed to characterize the reproductive biology of Plagioscion squamosissimus to subsidize fisheries management measures. Fish samples were taken bimonthly during the period from February 2012 to January 2013, totaling 182 specimens. In the laboratory, the biometry of each individual was performed and then a ventro-longitudinal incision was made to macroscopically observation of the gonads. Then they were fixed in Bouin solution for microscopic analysis and in Gilson's solution for analysis of fecundity. The specimens analyzed ranged from 11.5 to 38 cm in total length (TL). Allometry was negative for males and females. The sexual ratio was 1.2F: 1, with no significant difference. The mean length of first maturation was estimated at 15,303 cm. The spawning is synchronous in more than two groups, of the "multiple batch spawners" type. The absolute fecundity was estimated in 143,337 oocytes, characterizing high fecundity. The data obtained in this study showed that the lake of Viana was favorable to the growth and maintenance of P.squamosissimus.
Resumen.-Se estudió la biología reproductiva de Macrodon ancylodon, pez de importancia comercial ampliamente distribuido a lo largo de la costa atlántica de América del Sur, a partir de 240 muestras colectadas en la costa de la provincia de Maranhão, noreste de Brasil. Los especímenes variaron de 18,2 cm a 33,5 cm, exhibiendo alometría positiva. La longitud total de la primera madurez sexual fue de 21,13 cm. M. ancylodon tiene una maduración gonadal asincrónica y sería un desovador parcial dentro de un período reproductivo. Tanto la longitud como el peso de las hembras no afectaron la fecundidad relativa. El análisis del índice gonadosomático, factor de condición y frecuencia de los estadios de maduración muestra que M. ancylodon es capaz de reproducirse durante todo el año, a pesar de que se observaron picos de desove durante noviembre-diciembre y agosto-septiembre. Los resultados evidencian que el área de estudio es utilizada por M. ancylodon para la reproducción. Los datos obtenidos serán de gran valor para el desarrollo de estrategias de gestión de los recursos pesqueros.
The purpose of this study is to determine the parameters of the reproductive biology of seven commercial species at the Ramsar Site of the Baixada Maranhense to support fisheries management measures. The collections were carried out between 2012 and 2016. The reproductive period, sex ratio, weight-length relationship and first sexual maturity were evaluated for seven species of commercial importance. The sex ratio showed that females are predominant for all species, except for Plagioscion squamossissimus. The weight-length relationship indicated a greater investment in weight for Cichla monoculus and Hassar affinis, and a greater investment in length for Hoplias malabaricus, Plagioscion squamosissimus, Prochilodus lacustris, Pygocentrus nattereri, and Schizodon dissimilis. The reproductive activity of the species was predominant in the rainy season, but C. monoculus, H. malabaricus and P. lacustris showed the ability to reproduce in both seasons. As management measures for the region, it is suggested a change in the closed fishing season established by IBAMA, from December 1 to April 30, to ensure the protection of all commercial species in this study.
RESUMO O estudo da biologia reprodutiva é importante para determinar medidas protetivas visando à manutenção dos estoques pesqueiros. Desta forma, o presente estudo teve como objetivo determinar os aspectos da reprodução de Hassar affinis no Lago de Viana, Baixada Maranhense, Maranhão, Brasil. Os 147 espécimes foram provenientes da pesca comercial, coletados no período de fevereiro de 2012 a janeiro de 2013. Em laboratório, procedeu-se com a pesagem e medidas de cada indivíduo e posteriormente foi feita uma incisão ventro-longitudinal a fim de observar macroscopicamente as gônadas. Em seguida, foram fixadas em Solução de Bouin para análise microscópica e em Solução de Gilson para análise da fecundidade. A alometria negativa foi registrada para ambos os sexos, indicando maior incremento em comprimento do que em peso. A proporção sexual para o período total foi de 3,4 fêmeas para cada 1 macho. Houve maior intensidade reprodutiva nos bimestres fevereiro/março e abril/maio, indicando o período reprodutivo da espécie. Estima-se fecundidade absoluta média de 47.211 ovócitos. A primeira maturidade sexual é alcançada com 11,52 cm. A partir desses dados, portanto, são sugeridas medidas de gerenciamento, como o estabelecimento do período de reprodução da espécie durante os meses de fevereiro a maio, definição do tamanho mínimo de captura de 11,5 cm e, além disso, sugere-se o desenvolvimento de outros trabalhos com periodicidade mensal.
The principal aim was to assess the environmental perception of the fishermen, and implement educational activities, on an island in Brazil. Twelve people between the ages of 23 and 63 were interviewed, of whom 75% were male, and 58.33% did not complete their elementary education. Regarding social benefits, 33.33% receive a family allowance and 16.66% receive the so-called 'green allowance' (financial assistance to extremely poor families who live in areas of environmental preservation). Fishing remains the main economic activity (58.73%). The most common types of fishing gear are the 'zangarias' (41.66%) and 'muruadas' (41.66%), used to catch white shrimp (Litopenaeus schmitti), the main resource traded on the island (83.33%). All those interviewed reported a change in the size and weight of the catch in recent years (100%), and 75% attribute this to the types of trap used. Talks, films and booklets, as environmental education activities, contributed to community awareness. The population is familiar with the effects of fishing traps, and shows an interest in changing the situation.
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