Spatial and temporal distribution of benthic macroinvertebrates in a Southeastern Brazilian river.

A fauna de macroinvertebrados bentônicos é estruturada por fatores físicos e químicos que determinam os microhábitats, incluindo a disponibilidade de alimento, a existência de refúgios contra predadores e tempestades, o sucesso reprodutivo e outros parâmetros biológicos. O objetivo deste estudo foi investigar a distribuição espaço-temporal da comunidade de macroinvertebrados bentônicos na bacia do Rio Macaé, estado do Rio de Janeiro, Brasil. De acordo com o Habitat Assessment Field Data Sheet High Gradient Streams (Barbour et al., 1999), os cinco locais coletados são considerados como referência para propósito de biomonitoramento. Apesar das diferenças em parâmetros hidrográficos (largura, profundidade e vazão médias), os parâmetros físico-químicos e a composição dos grupos de alimentação funcional foram similares entre os locais, com exceção da área mais preservada, onde a porcentagem de organismos cortadores foi maior. De acordo com a análise de correspondência, há uma clara distinção entre áreas de remanso e de correnteza. De fato, o substrato folhiço de correnteza apresentou a fauna mais rica e abundante, enquanto o substrato folhiço de fundo apresentou o maior número de táxons exclusivos. A análise de agrupamento considerando os dados dos locais de coleta indicou que a variação temporal foi o fator mais importante na estruturação das comunidades nos hábitats estudados

Influence of water chemistry and environmental degradation on macroinvertebrate assemblages in a river basis in south-east Brazil.

Seven sites of the Guapimirim river basin were studied during three sampling periods based on the rain regime: end of wet season (May 1998), dry season (August 1998), and wet season (January 1999). Four substrates were collected at each site: sand, stony substrates, litter in pool areas and litter in riffle areas. Relationships between macroinvertebrate assemblages, water chemistry variables and environmental degradation were examined using canonical correspondence analysis (CCA). According to CCA, concentrations of dissolved oxygen and chloride, and the environmental degradation, measured by the Riparian Channel Environment index, exhibited the strongest relationship to macroinvertebrate assemblages. Overall, the loss of community diversity measured by the Shannon Index along the degradation gradient was observed. Some taxa were shown to be sensitive to water pollution, especially among Plecoptera, Trichoptera, Coleoptera and some Ephemeroptera, while others such as Simuliidae, Odonata and molluscs were tolerant to moderate levels of pollutants. The Chironomidae were the only group tolerant to a high level of pollutants and degradation

Good Mates Retain Us Right: Investigating the Relationship between Mate Retention Strategies, Mate Value and Relationship Satisfaction

Mate retention strategies are an important tool in keeping a partner, and their use is determined by the mate value (MV) of the partner one is trying to keep. The type of strategy used is also dependent on one’s own MV: mates of lower MV are more prone to exhibiting strategies that are cost-inflicting for their partners, whereas partner-benefiting strategies are used by mates of higher value. The type of strategies used affects relationship satisfaction (RS), and is also affected by the perceived difference in MVs. However, it is unclear how someone’s perception of their partner’s MV is related to that partner’s behavior and their own RS. To this aim, we investigated the relationship between these variables on a sample of 178 couples. Our results showed that benefit-inducing strategies were used more by—and towards—partners of higher MV, and were positively connected with RS. Cost-inflicting strategies were more used by—and towards—partners of lower MV, and were negatively connected with RS. Less MV difference was positively correlated with RS and benefiting strategies, and negatively correlated with cost-inflicting strategies. It seems that good mates use strategies that benefit their partners, which, in turn, make them more valuable and, consequently, their partner more satisfied

Multistate product traceforward investigation to link imported romaine lettuce to a US cyclosporiasis outbreak – Nebraska, Texas, and Florida, June–August 2013

During June–August 2013, 25 US states reported 631 cyclosporiasis cases including Nebraska and Iowa where a regional investigation implicated common-source imported salad mix served in two chain restaurants. At least two common-origin growing fields were likely sources of contaminated romaine lettuce. Using producer- and distributor-provided data, we conducted a grower-specific traceforward investigation to reveal exposures of ill US residents elsewhere who reported symptom onset during 11 June–1 July 2013, the time period established in the Nebraska and Iowa investigation. Romaine lettuce shipped on 2–6 June from one of these Mexico-origin growing fields likely caused cyclosporiasis in 78 persons reporting illness onsets from 11 June to 1 July in Nebraska, Texas, and Florida. Nationwide, 97% (314/324) of persons confirmed with cyclosporiasis with symptom onset from 11 June to 1 July 2013 resided in 11 central and eastern US states receiving approximately two-thirds of romaine lettuce from this field. This grower’s production practices should be investigated to determine potential sources of contamination and to develop recommendations to prevent future illnesses

Ground--state energies and widths of 5^5He and 5^5Li

We extract energies and widths of the ground states of $^5$He and $^5$Li from recent single--level R--matrix fits to the spectra of the $^3$H$({\rm d},\gamma$)$^5$He and the $^3$He$({\rm d},\gamma$)$^5$Li reactions. The widths obtained differ significantly from the formal R--matrix values but they are close to those measured as full widths at half maxima of the spectra in various experiments. The energies are somewhat lower than those given by usual estimates of the peak positions. The extracted values are close to the S--matrix poles calculated previously from the multi--term analyses of the N-$^4$He elastic scattering data.Comment: 3 pages, no figures, uses revtex.sty, accepted for publication in PRC, uuencoded postscript and tex-files available at ftp://is1.kph.tuwien.ac.at/pub/ohu/fwidth.u

Sources of dissolved organic carbon in small volcanic mountainous tropical rivers, examples from Guadeloupe (French West Indies)

International audienceIn the tropical zone, small watersheds are affected by intense meteorological events. These events play an important role in the erosion of soils and therefore on the sources of organic carbon in small tropical rivers. We studied the geochemistry of two soils on Basse-Terre Island (French West Indies, FWI): ferralitic soil and Andosol. The two studied soils are very similar in terms of soil organic matter (SOM) and soil solution parameters. The total organic carbon (TOC) and total nitrogen (TN) contents vary between 1.7 and 92 g kg‐1 and between 0.1 and 5.5 g kg‐1, respectively, with the highest concentrations observed in the topsoil. The C/N ratios are relatively constant throughout the soil profiles (ca. 12). The carbon isotopic composition of SOM varies between ‐27.3‰ and ‐22.7‰ and presents an enrichment with increasing depth of soil profiles. Dissolved organic carbon (DOC) concentrations in soil solutions, varying from 3.2 to 91.3 mg L‐1, are similar for the both extraction used in lab (with milliQ water and Ca(NO3)2) but are higher than those measured in soil solutions sampled from lysimeters (0.65–1.46 mg L‐1). The isotopic compositions of DOC obtained by extractions and SOM are comparable, with δ13C values ranging from ‐28.6‰ to ‐25.8‰. The DOC sampled from lysimeters is systematically depleted in 13C compared to DOC obtained by extractions, with δ13C values of ‐33.8‰ to ‐30.6‰. The enrichment of δ13C of SOM through the soil profiles is either consistent with the carbon isotopic fractionation of SOM by decomposing organisms, or the differential mineralization of both labile and stable carbon stocks in soils. DOC concentrations in stream waters vary between 0.46 and 5.75 mg L‐1, and are generally lower during low water level than floods. The isotopic compositions of DOC in the rivers range from ‐38.9‰ to ‐27.2‰, with δ13C values, which are more depleted in 13C during low water level than flood events. The δ13CDOC of water river samples and soil solutions obtained by extraction and collected with lysimeters demonstrates that the DOC in rivers derives essentially from both the lixiviation of the soil surface layers during floods and groundwater flow during low water levels. Lixiviation of soil surface layers can be boosted by significant increases of intensity and duration of meteorological events and can strongly favor the release of surface soil organic matter in rivers and the impoverishment in nutrients of soil surface layers

The uptake of selenium by perennial ryegrass in soils of different organic matter contents receiving sheep excreta

Background and Aims The intake of selenium, an essential element for animals and humans, in ruminants is largely determined by selenium concentration in ingested forages, which take up selenium mainly from soil. Ruminant excreta is a common source of organic fertilizer, which provides both nutrients and organic matter. This study aims to unentangle the unclear effect of applying different types of ruminant excreta in soils of different organic matter contents on selenium uptake by forage. Methods Perennial ryegrass (Lolium perenne) was grown in soils of different organic matter contents. Urine and/or feces collected from sheep fed with organic or inorganic mineral supplements, including selenium, were applied to the soils. The selenium in the collected samples were analyzed using ICP-MS. The associated biogeochemical reactions were scrutinized by wet chemistry. Results The application of urine and/or feces resulted in either the same or lower selenium concentrations in perennial ryegrass. The excreta type did not affect total selenium accumulation in grass grown in low organic matter soil, whereas in high organic matter soil, feces resulted in significantly lower total selenium accumulation than urine, which was attributed to a possible interaction of selenium sorption in soil and microbial reduction of Se. Conclusion This one-time excreta application did not increase, but further decrease in some treatments, selenium concentration and accumulation in the perennial ryegrass. Consequently, to increase ruminant selenium intake, supplementing selenium directly to animals is more recommended than applying animal manure to soil, which might drive selenium reduction and decrease selenium uptake by grass