Accumulation and effects of copper on aquatic macrophytes Potamogeton pectinatus L.: Potential application to environmental monitoring and phytoremediation.

This study investigated the ability of Potamogeton pectinatus L. to accumulate copper and its effects on plants. In accumulation tests, macrophytes were exposed (96 h) to different copper concentrations (0-1000 µM) and the metal was measured in media and plant tissues (roots, stems and leaves) to determine the bioconcentration factor (BCF). Plants accumulated high concentrations of copper in a dose-dependent manner and roots was the main organ for copper accumulation. However, the more copper increased in water, the more BCF values decreased. It may be due to either saturation of copper uptake or down-regulation of metal uptake by plants. In the physiological and morphological analyses, plants were kept (96 h) in Hoagland nutrient solution without copper, in full Hoagland solution (0.5 µM Cu) and in Hoagland medium with copper from 1 to 100 µM. The absence and the presence of copper above to 1 µM inhibited photosynthesis. Chlorophylls and carotenoid levels also decreased with the excess of copper, a fact that may have affected the photosystem II-dependent of chlorophyll and caused photosynthesis suppression. Only macrophytes at 10 µM Cu showed decrease in length and number of leaves on the 10th day of the test, when they died. Chlorosis and necrosis were observed in control groups and groups with extra copper, but not in Hoalgand group. Overall, the macrophyte P. pectinatus can be considered a suitable plant for monitoring environments contaminated by copper, based on results of copper accumulation in the plant, decrease in pigment concentration and presence of chlorosis and necrosis. However, values of BCF based on fresh water tissues was not proper to indicate the use of P. pectinatus for cleaning environments contaminated by copper.

Using a toxicity test with Ruppia maritima (Linnaeus) to assess the effects of Roundup.

Glyphosate, the active ingredient in Monsanto's broad-spectrum herbicide Roundup, consists of one of the most used pesticides worldwide, but its effects on the marine flora are still not well understood. Were examined Roundup toxic effects on Ruppia maritima specimens collected from Jansen Lagoon (São Luís, MA, Brazil) and acclimatized under laboratory conditions. The numbers of new and dead leaves, the root and leaf length, the chlorophyll a content, and the weight of R. maritima branches were determined before and after exposure to different Roundup concentrations for seven days. High concentrations caused a significant lethal effect. In addition, significant changes were observed in the wet and dry weights, the number and length of the leaves, and the chlorophyll a content. Leaf elongation was observed in the branches exposed to low concentrations, and this change was likely activated as a compensatory mechanism. The results indicate that high concentrations of this herbicide may compromise estuarine flora.

Feeding habits of capybaras (Hydrochoerus hydrochaeris, Linnaeus 1766), in the Ecological Reserve of Taim (ESEC - Taim) - south of Brazil

The aim of this study was to determine feeding habitats of capybaras in the ESEC-Taim (RS, Brazil), using microhistological analyses of feces. Data were analyzed seasonally. In 172 samples analyzed, 17 species were identified, with predominance of Poaceae. Zizaniopsis bonariensis was the most frequent species in winter (38 percent), spring (32 percent) and summer (26.5 percent) and Paspalum disthichum in fall (31.5 percent). A observed increase in vegetation consumption during summer might be due to the food quality. Capybaras showed an opportunistic behavior in the winter and summer and a more selective behavior in spring and fall. Capybaras from the ESEC-Taim varied diet according to the season and alimentary availability.

O principal objetivo deste estudo foi determinar os hábitos alimentares das capivaras na ESEC-Taim baseado na análise microhistologica de suas fezes. Os dados foram analisados sazonalmente. Em 172 amostras analisadas, foram identificadas 17 espécies, com predominância de Poaceae. Zizaniopsis bonariensis foi a espécie mais freqüente no inverno (38 por cento), primavera (32 por cento) e verão (26,5 por cento) e Paspalum disthichum no outono (31,5 por cento). O aumento no consumo da vegetação durante o verão pode ser explicado devido à qualidade da vegetação. As capivaras mostram um comportamento de oportunismo nas estações de inverno e verão e um comportamento mais seletivo na primavera e outono. Concluindo, as capivaras da ESEC-Taim variam sua dieta de acordo com a estação e a disponibilidade de comida.