Magnetospheric substorm effects on energetic electrons in the outer Van Allen belt /Summary of technical report CR-137/

Substorm-associated acceleration effects on electron increases in post-midnight sector of outer radiation bel

Experimental verification of drift shell splitting in the distorted magnetosphere

OGO-3 and ATS-1 data used in experimental verification of drift shell splitting in distorted magnetospher

Água para a vida de qualidade.

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Benthic macroinvertebrates and degradation of phytomass as indicators of ecosystem functions in flooded rice cropping.

The objective of this work was to evaluate the ecosystem functions of a natural wetland and of artificially flooded rice areas, managed under organic and conventional systems, by phytomass degradation and by the colonization of this material by benthic macroinvertebrates. The experiment was carried out in a natural wetland area, and in two flooded rice areas managed under organic and conventional systems. Twenty-five decomposition bags filled with 10 g of dry vegetation were installed in each site. At 14, 28, 42, 56, and 70 days after the beginning of the experiment, five bags from each site were collected. Macroinvertebrates were identified and classified by functional trophic group. The number of species of benthic macroinvertebrates increased: natural wetland > organic system > conventional system. The Chironomidae group was present in all areas, confirming its food plasticity and adaptability to different substrates and environmental stress situations. The Amphipoda group was present only in the artificially flooded rice area, and the Acari, only in the natural wetland. The diversity of species in the natural wetland area was higher than in the artificially flooded rice area. Nutrient cycling, provided by phytomass decomposition, is affected by the management system, and the delay in this process causes a reduction of the ecosystem functions in the conventional system.Título em português: Macroinvertebrados betônicos e degradação da fitomassa como indicadores de funções ecossistêmicas em arroz irrigado por inundação

Structure and composition of the benthic macroinvertebrate community on wetland and irrigated rice cultivation.

Wetlands are environmentally and economically important ecosystems. The irrigated rice crops are considered artificial wetlands, because they offer food and refuge to different aquatic communities. The benthic macroinvertebrates are used to study environmental quality. The knowledge from the organisms which inhabit the natural and artificial wetlands can help to verify less harmful management practices in the agroecosystems. AIM: The aim of this research was to analyze and compare the benthic macroinvertebrate community from a wetland and an experimental kind of rice cultivation. METHODS: It was used dip nets 1 mm mesh every 15 days, with six repetitions in each place, from January to March 2010. After washing and screening them in the laboratory, the organisms were identified using stereoscope microscope and identification keys, and classified according to their functional trophic group. RESULTS: The whole organisms collected were 33,293 specimens. It was found 34 taxa, being 26 founded in the rice crops and 31 on the wetland. The natural wetland shows greater abundance, being responsible for 90.47% from the total abundance in this study. In the rice crop the abundance and the richness increased in the course of collection. However, it did not reach the values founded in the wetlands during the cultivation period. The most found groups in the two environmental were Belostomatidae and Planorbidae, while Hyalellidae and Elmidae were found only in the wetland, being a stress indicator in the wetland. CONCLUSIONS: The community structure including abundance, richness and composition was statistical different between wetlands and rice cultivation

Residual effect of Fipronil used in rice farming on non-target organisms.

This study evaluated changes in the composition of the benthic community of non-target organisms in rice crop fields due to residual effect one year after planting seeds treated with different Fipronil doses. Macroinvertebrates were collected during crop irrigation months (February, March and April/2012), with the aid of 1 mm hand net placed close to the ground of each plot, for 20 minutes, collected macroinvertebrates were classified according to its dietary habits function. Orizophagus oryzae larvae, the target organisms, were not found in groups treated with different Fipronil doses; they were only observed in the control treatment. Chironominae (Chironomidae: Diptera) larvae had their population reduced in comparison to the control treatment. However, the herein used insecticide doses did not show significant changes in the benthic macroinvertebrate community one year after their application

Guia de identificação de peixes associados a lavouras de arroz irrigado do extremo sul do Rio Grande do Sul.

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