ABSTRACT(Mosses as indicators of atmospheric metal deposition in an industrial area of southern Brazil). Caxias do Sul hosts the second largest metal-mechanic pole in Brazil, which increases the risk of atmospheric contamination. With the aim of identifying species that might be useful as indicators of atmospheric deposition of metals, 15 species of mosses from an urban and a rural setting were analyzed and compared with specimens deposited at the Herbarium of the Universidade de Caxias do Sul. Metal concentrations (Zn, Ni, Cd, Cr, Cu and Pb) were determined using Atomic Absorption Spectrometry (AAS). The Mann-Whitney test indicated concentrations of Zn, Cu, Pb and Cr that were significantly different between the urban and rural areas. Additionally, Concentrations of Zn, Cd, Cu and Pb were significantly higher in recently collected samples. The species Thuidium tomentosum Besch., Sematophyllum subpinnatum (Brid.) E. Britton, Helicodontium capillare (Hedw.) A. Jaeger, Schlotheimia jamesonii (W.-Arnott) Brid. and Meteorium deppei (Hornsch. ex Müll. Hal.) Mitt. are potential biomonitors of atmospheric metal deposition.
Canola crop productivity is benefited by bee pollination and it has been shown that bee communities can be affected by landscape composition. The aim of this study was to analyse the bee community and its relationship to canola seed production in agricultural areas. The density, abundance and richness of floral visitors of Brassica napus cultivar Hyola 61 in six commercial fields in southern Brazil were studied, and their relationships with seed production and the ratio of semi-natural, forested and agricultural areas surrounding the crops were examined. It was observed that canola fields of southern Brazil are surrounded by a homogeneous landscape dominated by agricultural areas. The survey of bees detected a low abundance and richness of native bees in contrast to the high abundance of Apis mellifera. Except for a negative correlation between the abundance of honey bees and the proportion of forested areas within a 2000 m radius from the field (R = -0.90; P = 0.012), no other correlations were found among bee abundance and richness and landscape composition. Although there was not a relationship between A. mellifera and seed set, there was a positive correlation between insect density and seed weight per plant (R = 0.87; P = 0.024). As honey bees were the most captured insect (79%), much of the pollination in this system was probably achieved by honey bees.
Hydrological stress as a limiting factor of the invasion ofLimnoperna fortunei (Dunker, 1857) in the Upper Paraná River (Brazil)Estresse hidrológico como fator limitante para a invasão de Limnoperna fortunei (Dunker,1857) River, including the São Simão hydroelectric reservoir. Physicochemical characteristics of the water were analysed, and a Stream Length-Gradient Index calculated for the study area. Results: Adult mussels were easily found attached to the hulls of barges that travel on this stretch of the Paraná-Tietê waterway and on vessels that were docked in the harbours of grain exporters located in São Simão (GO). However, no larvae or adults were found near the harbours or upstream from them at the São Simão hydroelectric reservoir. The pH and concentration of calcium and dissolved oxygen values among lotic habitats and the reservoir were similar: DO values were close to 7 mg.L -1 , the average pH was near 7, average values of total Ca ranged between 4 and 6 mg.L -1 and the chlorophyll-a levels were not restrictive to the mussel. Conclusion: Physical and chemical water parameters show that habitats were suitable for establishment of the mussel. In addition to a low pressure of propagules, this paper proposes some hydrological variables, such as the energy of the fluvial stretches, expressed by the Stream Length-Gradient Index and changes in flow downstream of the dam as barriers to the establishment of the species, discouraging larval settlement, and decreasing survival and recruitment.Keywords: Limnoperna fortunei, invasive species, Paraná River watershed, golden mussel. 2012, vol. 24, no. 1, p. 64-82 http://dx.doi.org/10.1590/S2179-975X2012005000027Hydrological stress as a limiting..., o pH médio está em torno de 7, os valores médios de Ca total variam entre 4 e 6 mg.L -1 e os níveis de clorofila a não são restritivos para esta espécie de mexilhão. Conclusão: As variáveis físico-químicas da água indicam que os habitats são adequados para o estabelecimento da espécie. Além de uma baixa pressão de propágulos, este trabalho propõe algumas variáveis hidrológicas, tais como, a energia dos trechos fluviais e mudanças da vazão a jusante da barragem, como barreiras para o estabelecimento da espécie, uma vez que estes aspectos podem desfavorecer a fixação e sobrevivência das larvas e diminuir o recrutamento.Palavras-chaves: Limnoperna fortunei, espécies invasoras, Bacia do rio Paraná, mexilhão dourado.
AIM: the aim of this study was to determine the ecological valence of benthic macroinvertebrates at different pollution levels in highland rivers and streams of Rio Grande do Sul; METHODS: the dataset proceeds from samplings performed between 2002-2011 in 35 lotic ecosystems. The Chemical Index was used to determine pollution levels. Indices of richness and Shannon diversity were applied to characterize the structure of benthic communities. The descriptors used to determine taxa's ecological valence were selected according to Coefficient of Variation and regression analyses. Groups of tolerance were identified using Interquartile range and cluster analysis; RESULTS: Conductivity and Chemical Index were the descriptors best related with diversity of benthic macroinvertebrate community. These metrics were used to determine the tolerance range of 38 taxa. Interquartile range and cluster analysis revealed three groups of taxa, according to their occurrence in different levels of pollution: taxa with narrow amplitudes, present at sites with very low or very high load of organic enrichment; taxa with moderate amplitude, found until moderately polluted sites; and taxa with occurrence in widespread environmental conditions. The results, when compared to other studies in Brazil, showed differences in some taxa's tolerance. This observation indicates the need to assess the bioindication potential of these taxa in genus and species level; CONCLUSION: the present study contributes to increase knowledge about the bioindicator potential of benthic macroinvertebrates. Therefore, the study supports an advanced biomonitoring of ecological quality in mountain streams of southern Brazil.
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