Repositório RCAAP

Universidade Federal de Sao Carlos

Universidade Federal de Minas Gerais

Financiadora de Estudos e Projetos

Universidade Federal de Minas Gerais

Universidade Federal de Sao Carlos

Universidade Federal de Sao Carlos

Financiadora de Estudos e Projetos

Universidade Federal de Sao Carlos

Universidade Federal de Sao Carlos

Universidade Federal de Sao Carlos

Universidade Federal de Sao Carlos

The human pressures on natural environments generate fragmentation and loss of habitat, one of the main threats to biodiversity. Using the terrestrial mammals as indicators, it were evaluated the ecological corridor Embrapa- Fazenda Engenho Velho (Old Mill Farm) and a silvopastoral system to determine if they actually mitigate the negative impacts of local farming. Four linear transects were laid in two fragments of semideciduous forest in the ecological corridor that connects them and made 24 observations, including the branch tunnels (one with 0.9 m in diameter and another with 2.5 x2m) under the highway Guilherme Scatena (that divides the ecological corridor) and its coasting. With the data was constructed a dendrogram of similarity (Jaccard coefficient). In the silvopastoral system and conventional grazing, were placed four cages (15x15x40cm) in each and 20 observations were made. The results demonstrate the presence of 27 species in the fragments, seven of which use the corridor and only two uses the tunnel passage. The similarity between the fragments is high (65%), but decays over the corridor (44%) and the tunnel passage (19%), which shows that the ecological corridor is not fulfilling its role of facilitating the exchange of individuals among the fragments for greater genetic variability in local populations. Furthermore, the coasting had 11 species (45% similarity with fragments), but no individual was found run over, suggesting that in this case, the speed bumps installed on the highway are the most effective tools for conservation than the actual tunnel passage. The largest tunnel presented seven species, but lacks the vegetation in the surroundings unlike smaller tunnel, suggesting that for the branch tunnels, it is extremely important to their size. In the silvopastoral system were found four individuals from three genera (Calomys, Akodon and Oligorizomys) and in the common grazing, eight individuals of the genus Calomys, suggesting that silvopastoral systems are better to maintain species richness. We conclude that there are viable alternatives to improve production and maintain biodiversity, native vegetation with the best connection, but the deployments must be accomplished effectively and not only for law enforcement, without ever having a monitoring of its function, as occurs in most rural areas of the country subjected to this type of activity. Also we can t think that the mere fact of clearing vegetation and deploy these systems are solutions to the environmental crisis, but to optimize the use of land already cleared for such deployment.

Financiadora de Estudos e Projetos

Financiadora de Estudos e Projetos

Financiadora de Estudos e Projetos

Universidade Federal de Minas Gerais

Financiadora de Estudos e Projetos

Universidade Federal de Minas Gerais

Universidade Federal de Minas Gerais

The trophic ecology is one of the most important aspects to understand the role of a species in the community and in the ecosystem functioning. Studies regarding the feeding of fishes coupled to the ecomorphology of a species become important tools in understanding their ecological role and position in the environment. The present study aimed to analyze the types and amount of food consumed by eleven species of fishes collected in six streams of Alcântara, Maranhão state, and assess their possible interspecific interactions. The specimens were collected in the rainy season, in January, and in the dry season, in November 2008. The analysis of morphology of the fish species was performed by measuring 17 characteristics and calculating 16 ecomorphological attributes. Analysis of the contents of the digestive tract was performed quantitatively and qualitatively. In order to determine the feeding habits of each species the frequency of occurrence, volume and alimentary index of each food item consumed were calculated. The majority of individuals analyzed was collected in the streams Igarapé do Camarajó and Igarapé do Brito. The trophic structure of fish assemblages of these two streams was diversified in both, rainy and dry seasons. The habit of the benthivore species Micropoecilia cf. parae and Apistogramma cf. piauienses was corroborated by their morphology. In the rainy season, there was a higher niche overlap in the diet of insectivorous species in the stream Igarapé do Camarajó, but the morphology of these species showed distinct spatial occupation of the habitat, thus allowing their coexistence. In the dry season most species had food overlap due to the consumption of organic detritus in the Igarapé do Camarajó stream and due to the consumption of chironomid larvae in the Igarapé do Brito stream. Fishes of Camarajó and Brito streams were more likely to feeding specialization in the rainy season and increased diversification of the items consumed during the dry season, indicated, respectively, by larger and smaller niche breadth. The changes in the trophic structure, in the niche overlap and in the niche breadth of fish community in the six streams studied indicate that fluctuations on the hydrological cycle in these streams are an important factor in the throphic dynamics of these fish communities.