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The reliability of using the abundance of Sporormiella spores as a proxy for the presence and abundance of megaherbivores was tested in southern Brazil. Mud-water interface samples from nine lakes, in which cattle-use was categorized as high, medium, or low, were assayed for Sporormiella representation. The sampling design allowed an analysis of both the influence of the number of animals using the shoreline and the distance of the sampling site from the nearest shoreline. Sporormiella was found to be a reliable proxy for the presence of large livestock. The concentration and abundance of spores declined from the edge of the lake toward the center, with the strongest response being in sites with high livestock use. Consistent with prior studies in temperate regions, we find that Sporormiella spores are a useful proxy to study the extinction of Pleistocene megafauna or the arrival of European livestock in Neotropical landscapes. Keywords: Extinction, fossil pollen, lake sediment, livestock, Pleistocene Megafauna, Sporormiella spores. Resumo: A confiabilidade dos valores de Sporormiella como um proxy para estimar a presenc¸a e abundância de megaherbívoros foi testada na região sudeste do Brasil. Amostras superficiais de nove lagos, categorizados quanto a presenc¸a de gados em alto, médio e baixo uso do seu entorno foram coletadas para a análise de abundância de Sporormiella. O modelo amostral aplicado permitiu a interpretac¸ão tanto da influência do número de animais que usam a margem do lago quanto a distância da margem do lago sobre a quantidade de esporos encontrados. As análises indicam que esporos de Sporormiella é um excelente proxy para detectar a presenc¸a de grandes herbívoros. A concentrac¸ão e abundância de esporos reduz em direc¸ão ao centro do lago, o que fica mais evidente em locais com alto uso do entorno do lago por esses animais. Consistente com estudos realizados em regiões temperadas, nós concluímos que o uso de Sporormiella se mostra de grande valia para entender a extinc¸ão da megafauna do Pleistoceno como também a introduc¸ão de animais nas paisagens neotropicais.

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Harmful cyanobacterial blooms (cyanoHABs) pose threats to human and animal health due to the production of harmful cyanotoxins. Microcystis aeruginosa is a common cyanobacterium associated with these blooms and is responsible for producing the potent cyclic hepatotoxin microcystin-LR (MC-LR). Concerns over the public health implications of these toxins in water supplies have increased due to rising occurrence of these blooms. High energy electron beam (eBeam) irradiation technology presents a promising strategy for the mitigation of both cyanobacterial cells and cyanotoxins within the water treatment process. However, it is imperative that both cellular and chemical responses to eBeam irradiation are understood to ensure efficient treatment. We sought to investigate the effect of eBeam irradiation on M. aeruginosa cells and MC-LR degradation. Results indicate that doses as low as 2 kGy are lethal to M. aeruginosa cells and induce cell lysis. Even lower doses are required for degradation of the parent MC-LR toxin. However, it was observed that there is a delay in cell lysis after irradiation where M. aeruginosa cells may still be metabolically active and able to synthesize microcystin. These results suggest that eBeam may be suitable for cyanoHAB mitigation in water treatment if employed following cell lysis.