Pomacea canaliculata es un gasterópodo dulceacuícola perteneciente a la familia Ampullariidae, cuyo rango natural de distribución se extiende desde el sur de Brasil hasta el sur bonaerense. Esta especie ha sido introducida accidental o intencionalmente en numerosos países, y es considerada uno de los 100 peores invasores a nivel mundial. El objetivo de esta tesis fue analizar los determinantes de la distribución espacial de P. canaliculata a distintas escalas espaciales. Específicamente se estudió el grado de dependencia de la respiración aérea, la velocidad de desprendimiento, el efecto de la corriente sobre la dispersión y el efecto de la temperatu-ra y el tiempo de exposición sobre la actividad. También se caracterizó cuantitativamente su microhábitat y se exploraron la distribución entre y dentro de los arroyos de la cuenca de las Lagunas Encadenadas del Oeste y sus patrones tempora-les de actividad. Los resultados obtenidos aquí mostraron que la restricción en la respiración aérea afecta negativamente la actividad y la supervivencia y que sus efectos empeoran con la temperatura y la polución del agua. La actividad se incre-menta con temperaturas entre 10 y 30C pero el tiempo de exposición carece de importancia, salvo a temperaturas superiores a 30C y en aguas polutas. La velocidad de desprendimiento fluctuó entre 0.07 y 1.64 m.s-1, indicando que P. canaliculata puede soportar, por un período corto, velocidades que se encuentran entre las máximas registradas en los arroyos de la cuenca de las Encadenadas del Oeste. Velocidades de la corriente menores a 0.3 m.s-1 no influyen sobre la tasa y dirección de dispersión por reptación. No hay una respuesta reotáctica positiva que compense los eventos de deriva aguas abajo, probablemente dificultando la coloniza-ción de tramos cercanos a las sierras. Los microhábitats más utilizados por esta especie se caracterizaron por su proximi-dad a la orilla o a sustratos emergentes aptos para ventilar el pulmón, velocidades de la corriente que no interfieren con las actividades de rutina (menores a 0.3 m.s-1) y sedimentos finos ricos en materia orgánica o abundancia de macrófitas y detritos. La efectividad de algunas medidas de control podría incrementarse reuniendo esfuerzos donde se concentran los caracoles debido a su dependencia del acceso al aire. El por-centaje de caracoles activos en la cuenca de las Encadena-das del Oeste fluctuó entre 0 y 100% durante el año. En la estación fría la mayoría de los caracoles estaban inactivos pero aparentemente no entran en un estado letárgico profundo y persistente, sino que muestran una respuesta rápida a cambios de temperatura, reactivándose tan pronto como las condiciones sean favorables. A pesar de que algunas variables ambientales influyeron sobre la distribución de P. canaliculata entre y dentro de los arroyos de la cuenca de las Encadenadas del Oeste, ninguna resultó determinante de su presencia. Todos los arroyos serían habitables para esta especie, aunque sólo en algunos las poblaciones podrían permanecer a largo plazo. Probablemente, las condiciones climáticas e hidrológicas, muy variables e impredecibles en esta región, sean determinantes de eventos de extinción-colonización y, en consecuencia, de su distribución en esta cuenca. / Pomacea canaliculata is a freshwater snail belonging to the family Ampullariidae, whose natural range of distribution extends from southern Brazil to southern Buenos Aires Province in Argentina. This species has been introduced either accidentally or intentionally to many countries and is considered to be one of the 100 worst invaders worldwide. The aim of this thesis was to analyze the determinants of the spatial distribution of P. canaliculata at different spatial scales. Specifically, the dependence on aerial respiration, the effect of water velocity on detachment and dispersal, and the effects of temperature and exposure time on activity were investigated. In addition, its microhabitat was characterized quantitatively and the distribution among and within streams in the Encadenadas del Oeste basin (Buenos Aires Province, Argentina) and the temporal patterns of activity were explored. The experimental results showed that a restriction in aerial respiration negatively affected activity and survival and that its effects worsened with increasing temperatures and water fouling. Activity increased with temperature between 10 and 30C but exposure time was irrelevant, except at temperatures above 30C and in fouled waters. The detachment velocity ranged from 0.07 to 1.64 m.s-1, indicating that P. canaliculata can resist, at least for short periods, velocities that were among the highest recorded in the streams of Encadenadas del Oeste basin. Current velocities below 0.3 m.s-1 did not influence dispersal rate and direction by crawling. A positive rheotactic response able to compensate the natural events of downstream drifting was not evident, so that the colonization of piedmont sections is unlikely. The microhabitats most frequently used by this species were characterized by their proximity to the shore or an emergent substratum suitable for lung ventilation, by water velocities not interfering with routine activities (below 0.3 m.s-1), and by fine sediments rich in organic matter or abundance of macrophytes and detritus. The effectiveness of some control measures could be increased by focusing efforts on areas where the snails are concentrated due to their dependence on access to air. The percentage of active snails in Encadenadas del Oeste basin fluctuated between 0 and 100% along the year. During the cold season most of the snails were inactive though they apparently not enter a deep and persistent lethargic state but show a rather quick response to temperature changes, being able to reactivate as soon as conditions become favorable. Despite the fact that some environmental variables influenced the distribution of P. canaliculata among and within the streams of Encadenadas del Oeste basin, none was determinant of its presence. All streams would be habitable for this species, but only in some of them populations would be able to persist long term. Probably, the climatic and hydrological conditions, which are highly variable and unpredictable in this region, are determi-nants of extinction-colonization events and, consequently, of its distribution in the streams of this basin.

Orientador: José Alves de Freitas Neto / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciencias Humanas / Made available in DSpace on 2018-08-21T21:13:34Z (GMT). No. of bitstreams: 1 Tolentino_MarcosOliveiraAmorim_M.pdf: 1842815 bytes, checksum: 0061fafe25fe110e75bd23cd14680a42 (MD5) Previous issue date: 2012 / Resumo: Esta dissertação visa analisar as comemorações anuais em torno do episódio La noche de los lápices, entre os anos de 1990 e 1996. Tal episódio refere-se a uma série de procedimentos orientados à repressão do movimento estudantil secundarista, ocorridos entre 15 e 21 de setembro de 1976, na cidade de La Plata. Trata-se de um dos casos emblemáticos que se instauraram na memória coletiva da sociedade argentina no período da reconstrução democrática, acerca da violência e da repressão sistemática dos sete anos da mais recente ditadura civil-militar no país (1976-1983). O nosso objetivo é discutir as relações da sociedade e das instituições estatais argentinas com as memórias do episódio em questão, e consequentemente com o mais recente passado ditatorial, a partir da formação de circuitos de memórias nos quais discursos e práticas de rememoração garantem a permanência deste como um passado presente. Para tanto, utilizamos a documentação produzida e arquivada no Arquivo da antiga Dirección de Inteligencia de la Policía de la Provincia de Buenos Aires (DIPBA), serviço de inteligência que funcionou na Argentina entre os anos de 1956 e 1998. A nossa escolha permite mapear as diferentes iniciativas ocorridas anualmente no dia 16 de setembro, além de identificar os critérios que (re) significaram a elaboração de memórias em torno da data. A documentação em questão traz ao circuito de memórias um ator estatal, o órgão de vigilância política e social, e a necessidade de problematizarmos o seu funcionamento durante o período democrático que seguiu a mais recente ditadura civil-militar / Abstract: This dissertation analyses the annual commemoration of the episode La noche de los lápices, from 1990 to 1996. This episode refers to a series of procedures aimed at the repression of the sophomore student movement, occurred between 15 and 21 September 1976 in the city of La Plata. This is one of the emblematic cases which have consolidated in the collective memory of Argentine society in the period of democratic reconstruction, about violence and the systematic repression of the seven years of the most recent civil-military dictatorship in Brazil (1976-1983).Our goal is to discuss the relations of society and Argentine state institutions with memories of the episode in question, and therefore with the most recent dictatorial past, from the formation of circuits in which memories discourses and practices of remembering guarantee the permanence of that as a last present. We used the documents produced and filed in the Archives of former Dirección de Inteligencia de la Policía de la Provincia de Buenos Aires (DIPBA), an intelligence service that worked in Argentina from 1956 to 1998. Our choice enables mapping the different initiatives that occur annually on the 16th of September, in addition to identifying the criteria that (re) mean the creation of memories about the date. The referred documents bring to the circuit of memories a new actor in this study, the national surveillance social policy. And most of all its necessary to question its operation during the democratic period that followed the latest civil-military dictatorship / Mestrado / Politica, Memoria e Cidade / Mestre em História

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