Tropical wetlands such as the Pantanal help regulate global biogeochemical cycles, but climate change is modifying these environments. Controls on environmental changes can potentially be assessed from ancient, well-dated lacustrine sedimentary records. An integrated field and laboratory approach was undertaken to study the limnogeology of Lake Uberaba in the northern Pantanal, and test whether the lake has preserved a reliable record of environmental change in its strata. This study was designed to understand how the basin accumulates sediment and to assess its sensitivity to hydroclimatic variability. The data showed that modern Lake Uberaba is a highly dynamic, freshwater fluvial-lacustrine basin. Modern lake floor sediments are largely siliciclastic silts, with limited organic matter content and abundant sponge spicules. This sedimentary composition reflects the lake’s open hydrology and well-mixed water column. Limited data from sediment cores indicates that Lake Uberaba may have formed ~1760 CE, following an abrupt transgression over an oxidized floodplain depositional environment. The stratal contact between lacustrine and floodplain deposits suggests the presence of an erosional unconformity, the timing and duration of which remains unknown. The environmental change favoring lake formation appears to be linked to increased effective precipitation provided by the Intertropical Convergence Zone (ITCZ) in the northern Pantanal.

Made available in DSpace on 2016-04-28T20:16:26Z (GMT). No. of bitstreams: 1 2008- Paulo Henrique Duarte.pdf: 2250009 bytes, checksum: dd3eac04ae943ebe159aceec0bddbead (MD5) Previous issue date: 2008-02-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This research is a study about the tick fauna of Pantanal wetlands, MS, Brazil. Evaluation of cattle-raising on ticks populations, a detailed study on tick feeding on feral pigs and a list of ticks witch are reported in the study area are included. The cattle-raising impact was evaluated by trapping free-living ticks using a CO2 tick-trap. The traps were distributed in two areas: protected area, and the Nhumirim Ranch. Both areas are contiguous and locate at sub-region of Nhecol?ndia (18?59 S and 56?39 W), Pantanal of Mato Grosso do Sul state, Brazil. In each area, four habitat types were selected: cerrado (tropical savanna), forest patches, lakes and soda lakes. The last two are temporary lagoons of fresh and salted water, respectively. A total of 980 nymphs, 613 adults and 13 larvae of ticks of the genus Amblyomma were collected in 256 hours of collection. In a pen of calves infested by Ornithodoros rostratus 114 specimens were collected in just two hours including larvae, nymphs and adults. Adults of A. cajennense and A. parvum were more abundant in the savanna at Nhumirim Ranch, but did not differ among habitat types at protected area. There was a tendency of having more nymphs in Nhumirim Ranch than in protected area. The second conduced experiment was the comparison of the tick fauna of feral pigs at dry and wet seasons. A total of 44 feral pigs were examined and the species found were A. cajennense, A. parvum e O. rostratus. More adult ticks were collected in the dry season. Ecological and epidemiological aspects were discussed. Feral pigs are introduced specie and the role of this mammal on amplifying Amblyomma cajennense is clear. O. rostratus seems to be accidental parasite of feral pigs. The last part is a commented list of species including collected data and scientific literature. Up to day 18 tick s specie are reported on Pantanal wetlands including Argasidae (two) and Ixodidae (16) tick s species. The main genus was Amblyomma and the same species founded on wildlife are present on domestic animals and humans. / A presente tese ? um estudo sobre o impacto da bovinocultura extensiva sobre a popula??o de carrapatos, e um levantamento da fauna de carrapatos da regi?o com um estudo detalhado sobre a ixodofauna do porco monteiro. Para o estudo de impacto da bovinocultura, foram utilizadas armadilhas de CO2, distribu?das em duas ?reas: Reserva Biol?gica e Fazenda Nhumirim. Ambas as ?reas s?o contiguas e est?o localizadas na sub-regi?o da Nhecol?ndia (18?59 S e 56?39 W). Em cada ?rea quatro tipos de habitat foram selecionados: cerrado, mata, baia e salina. Os dois ?ltimos s?o lagoas tempor?rias de ?gua doce e salobra, respectivamente. Na totalidade foram coletadas 980 ninfas, 613 adultos e 13 larvas de carrapatos do g?nero Amblyomma em 256 horas de coletas. Em um bezerreiro infestado por Ornithodoros rostratus, 114 exemplares, dentre larvas ninfas e adultos foram coletados em apenas duas horas de atividade. Adultos de A. cajennense e A. parvum foram mais abundantes no cerrado da Fazenda, mas n?o diferiram entre os tipos de habitat na Reserva Biol?gica. Existe uma tend?ncia para uma maior abund?ncia de ninfas de Amblyomma na Fazenda do que na Reserva Biol?gica. O outro estudo realizado comparou a fauna de carrapatos adultos dos porcos monteiros entre as esta??es, cheia e seca. Os carrapatos encontrados foram A. cajennense, A. parvum e O. rostratus. E foram encontrados mais carrapatos adultos na seca que na cheia, foi discutida a import?ncia eco-epidemiol?gica destas rela??es parasit?rias, principalmente em fun??o do Porco monteiro ser uma esp?cie introduzida na regi?o. O ?ltimo cap?tulo apresenta uma lista comentada que reuniu os dados coletados pelo autor bem como resultados publicados na literatura cient?fica. Nos dias de hoje, existe registro de 18 esp?cies de carrapatos inclu?do as fam?lias Argasidae (2) e Ixodidae (16). O g?nero mais comum foi Amblyomma e as mesmas esp?cies de carrapatos foram comuns para animais selvagens, dom?sticos e para o homem, o que constitui uma rede complexa e din?mica de hospedeiros e parasitas.