Feeding habits of coypu (Myocastor coypus Molina 1978) in the wetlands of the Southern region of Brazil

The aim of this study was to determine the diet of coypu (Myocastor coypus) in two areas (Santa Isabel do Sul wetlands – Area 1, and Santa Marta Farm – Area 2) in the Southern region of Brazil, using microhistological analyses of feces. Twenty-four plant species were identified from collected feces samples. Among the identified species, nine are common in the animals’ diet in both areas; the presence of Oriza sativa was not detected in any of the samples. Among the identified species, 84% and 54% of the coypu’s diet from Areas 1 and 2, respectively, are aquatic plants. Poaceae family was most common, being found in 82% of the samples from both areas. Paspalum disthichum (Area 1) and Panicum tricholaenoides (Area 2) were the most frequent species on the coypu’s diet. The diet comparison for both areas indicates that feeding habits vary depending on the type of habitat, environmental conditions and food availability. The absence of rice in our analysis may be an indication for the preservation of native areas around watercourses, so as to prevent coypu from invading irrigated crops.O objetivo deste estudo foi determinar a dieta do ratão-dobanhado (Myocastor coypus), em duas regiões (áreas alagadas em Santa Isabel do Sul – área 1 e Fazenda Santa Marta – área 2), na região sul do Brasil, utilizando microhistological análises de fezes. Foram identificadas 24 espécies de plantas nas amostras de fezes coletadas. Entre as espécies identificadas, nove são comuns a dieta dos animais de ambas as áreas, não sendo detectada a presença de Oriza sativa em nenhuma das amostras. Entre as espécies identificadas, 84% e 54% da dieta do ratão-do-banhado, nas áreas 1 e 2 respectivamente, são plantas aquáticas. A família Poaceae foi a mais abundante, sendo encontrada em 82% das amostras de ambas as áreas. Paspalum disthichum (área 1) e Panicum tricholaenoides (área 2), foram as espécies mais frequentes na dieta do ratão-do-banhado. A comparação da dieta de ambas as áreas mostrou que a alimentação varia dependendo do tipo de habitat, condições ambientais e de disponibilidade alimentar. A ausência de arroz na nossa análise pode ser um indicativo de que a preservação de áreas nativas ao redor de cursos d’água, evita que o ratão-do-banhado utilize as culturas de arroz

Effects of crude oil on survival, morphology, and anatomy of two aquatic macrophytes from the Amazon floodplains

Aquatic herbaceous macrophytes grow in profusion in the Amazon fertile varzea floodplains. A large number of species occur but only a few are particularly abundant, supporting food chains, contributing substantially to carbon and nutrient cycles. Their growth and role in the ecosystem depend, among other, on its life cycles and habits, floating or semi-aquatic. Although in the last decades, petrolif-erous activity intensified in the Central Amazon region and so did oil spills, the effect of petroleum on the native aquatic plants is unknown. The present study was designed to test experimentally the survival and morpho-anatomical modifications of the free floating water hyacinth Eichhornia crassipes and the semi-aquatic grass Echinochloa polystachya to 10 different concentrations of crude oil. Higher concentrations of crude oil caused the mortality in both species; however, lethal dose (LD50) values showed that E. polystachya was more sensitive than E. crassipes. Despite the higher tolerance of E. crassipes, the inhibition of root and leaf growth as well as anatomical modifications in leaves were registered in higher concentrations. Additionally, the oil caused a reduction in leaf numbers in both species. Although mortality of the floating species was lower, it may increases over time, since important alterations in morphology and anatomy occurred. These results show that oil spills in the Amazon varzea can cause severe alterations in the aquatic flora and in the floodplain dynamics. © 2009 Springer Science+Business Media B.V