scholarly journals Impact of Zirconium on Freshwater Periphytic Microorganisms

Environments ◽  
2019 ◽  
Vol 6 (10) ◽  
pp. 111 ◽  
Author(s):  
Caroline ◽  
Soizic ◽  
Jacky ◽  
Claude

The majority of studies on biofilms have focused on autotrophic and bacterial taxa, without considering the potential effects on biofilm grazers. In this work, we investigated the effects of realistic environmental concentrations of zirconium (Zr) on periphyton algal growth and micromeiofauna biodiversity. Glass slides were submerged in a pond for four weeks to colonize biofilms and exposed for four weeks in aquaria to targeted Zr concentrations of 0, 1, and 10 nM, which were monitored over time (average measured concentrations were 0.2 ± 0.1, 0.5 ± 0.3, and 2.9 ± 0.3 nM Zr). The four-week exposure to the highest concentration (3 nM) affected the micromeiofauna structure of biofilms and modified the autotrophic biofilm structure by increasing the proportion of green algae and decreasing the abundance of cyanobacteria and brown algae. Rotifers and the ciliate Aspidisca cicada appeared to be the most sensitive organisms among the observed micromeiofauna. A toxic effect of Zr on rotifers could explain such results. Indirect effects, such as reduced food availability given the reduced algal growth in the presence of Zr, could also play a role in the changes of micromeiofauna community structure. These results are among the few published data on the effects of Zr.

2019 ◽  
Vol 13 (10) ◽  
pp. 1273-1282 ◽  
Author(s):  
Gianluca Galazzo ◽  
Danyta I Tedjo ◽  
Dion S J Wintjens ◽  
Paul H M Savelkoul ◽  
Ad A M Masclee ◽  
...  

Abstract Background Microbial shifts have been associated with disease activity in Crohn’s disease [CD], but findings on specific taxa are inconsistent. This may be due to differences in applied methods and cross-sectional study designs. We prospectively examined the faecal microbiota in adult CD patients with changing or stable disease course over time. Methods Faeces were collected at two time-points from 15 healthy control individuals [HCs], 35 CD patients who were in remission and who maintained remission [RRs], and 22 CD patients during remission and also during subsequent exacerbation [RAs]. The microbial composition was assessed by 16S rRNA [V4] gene sequencing. Results Compared with HCs, patients with CD had a lower microbial richness [p = 0.0002] and diversity [p = 0.005]. Moreover, the microbial community structure of a subset of patients, clustered apart from HCs, was characterized by low microbial diversity and Faecalibacterium abundance. Patients within this cluster did not differ with respect to long-term disease course compared with patients with a ‘healthy-appearing’ microbiota. Over time, microbial richness and diversity did not change in RR versus RA patients. Although the microbial community structure of both RR and RA patients was less stable over time compared with that of HCs, no differences were observed between the patient groups [p = 0.17]; nor was the stability impacted by Montreal classification, medication use, or surgery. Conclusion The altered microbiota composition and stability in CD was neither associated with disease activity nor long-term disease course, questioning its involvement in the development of an exacerbation. The aberrant microbiota composition in a subset of CD patients warrants further exploration of a more microbiota-driven etiology in this group.


2012 ◽  
Vol 37 (2) ◽  
pp. 206-226 ◽  
Author(s):  
Cherith A. Moses

Rock coasts are widespread in the tropics and exhibit particular morphologies that may be specific to their tropical, micro-tidal location. Notches are particularly well developed, often linked to onshore cliffs and fronted by subhorizontal platforms. Through a review of previously published data across the tropics, average cliff face erosion rates are calculated as 2.15 ± 2.62 mm a−1, intertidal erosion rates 3.03 ± 7.50 mm a−1 and subtidal erosion rates 0.96 ± 0.44 mm a−1. Intertidal erosion rates are variable within and across latitudinal ranges: within 10°N and S of the equator average rates are 1.42 ± 1.22 mm a−1; between latitudes of 10°and 20°, 0.88 ± 1.16 mm a−1 and between latitudes of 20°and 30°, 2.04 ± 2.57 mm a−1. A consideration of temporal variations in intertidal erosion rates provides insights into the potential impacts of climate change on the erosion dynamics of rock coasts in the tropics. This paper highlights some of the interactions over time and space between process and measurement that continue to limit our understanding of, and ability to model, the erosion dynamics of tropical rock coasts. It concludes by identifying potentially fruitful areas for future research.


2017 ◽  
Vol 12 (2) ◽  
pp. 172
Author(s):  
Sue F. Phelps

A Review of: Maloney, K., & Kemp, J. H. (2015). Changes in reference question complexity following the implementation of a proactive chat system: Implications for practice. College & Research Libraries, 76(7), 959-974. http://dx.doi.org/10.5860/crl.76.7.959 Abstract Objective – To determine whether the complexity of reference questions has changed over time; whether chat reference questions are more complex than those at the reference desk; and whether proactive chat increases the number and complexity of questions. Design – Literature review and library data analysis. Setting – Library of a doctoral degree granting university in the United States of America. Methods – The study was carried out in two parts. The first was a meta-analysis of published data with empirical findings about the complexity of questions received at library service points in relationship to staffing levels. The authors used seven studies published between 1977 and 2012 from their literature review to create a matrix to compare reference questions based on the staffing level required to answer the questions (e.g., by a nonprofessional, a generalist, or a librarian). They present these articles in chronological order to illustrate how questions have changed over time. They sorted questions by the service point at which they were asked, either through chat service or at a reference desk. In the second part of the study authors used the READ scale to categorize the complexity of questions asked at the reference desk and via proactive chat reference. They collected data for chat reference for six one-week periods over the course of eight months to provide a representative sample. They recorded reference desk questions for three of those same weeks. Both evaluators scored the data for a single week to norm their results, while the remaining data was coded independently. Main Results – The complexity of questions in the seven articles studied indicated change over time, shown in tables for desk and chat reference. One outlier, a study published in 1977 before reference tools and resources moved online, reported that 62% of questions asked could be answered by nonprofessionals, 38% by a trained generalist, and only 6% required a librarian. The six other studies were published after 2001 when most resources had moved online. Of the questions from these six, authors found a range of 74-90% could be answered by a non-professional, 12-16% by a generalist, and 0-11% required a librarian. Once chat reference was added there was more variation reported between studies, with generalist questions at 30-47% of those reported and 10-23% requiring a librarian. Though the underlying differences in the study designs do not allow for formal analysis, the seven studies indicate that more complex questions are asked via chat service than at the reference desk. Each staffing level was grouped and averaged for comparison. The 1977 study shows nonprofessional questions at 62%, generalist questions at 32%, and librarian questions at 6%. Reference desk questions in the post-2001 articles indicated 81% nonprofessional, 13% generalist, and 5% librarian questions. Post-2001 chat questions were at 49% nonprofessional, 36% generalist, and 15% at librarian level. In the second part of the study, the data coded using the READ scale and collected from the proactive chat system showed an increased number and complexity of questions. The authors identified 4% of questions were rated at a level 1 (e.g., directional, library hours), 30% at level 2 (e.g., known item searching), 39% at level 3 (e.g., reference questions), and 27% at level 4 requiring advanced expertise (e.g., using specialized databases or data sets). Authors combined questions at levels 5 and 6 due to low numbers, and did not describe these when reporting their study. In comparison, 15% of reference desk questions were at a level 3 on the READ scale, and 1% were at level 4. Conclusion – Proactive chat reference service increased the number and the complexity of questions over those received via the reference desk. The frequency of complex questions was too high for nonprofessional staff to refer questions to librarians, causing reevaluation of the tiered service model. Further, this study demonstrates that users still have questions about research, but for users to access services for these questions “reference service must be proactive, convenient, and expert to meet user expectations and research needs” (p. 972).


2005 ◽  
Vol 21 (2) ◽  
pp. 161-169 ◽  
Author(s):  
Violaine Nicolas ◽  
Patrick Barrière ◽  
Marc Colyn

The composition, structure and reproductive phenology of a shrew community were investigated for 1 y at two neighbouring sites in an undisturbed African forest of south-western Gabon. We captured 717 shrews, belonging to four genera and 10 species. The data were analysed to answer three main questions: (1) to what extent does the shrew abundance vary seasonally? (2) is there a shift in species dominance over time? and (3) does the intensity of breeding activity vary seasonally? The number of species captured varied seasonally and tended to be least during the period of minimal trap success. Trap success for the four most abundant species (Sylvisorex johnstoni, Crocidura batesi, Paracrocidura schoutedeni and Sylvisorex ollula) varied seasonally with a minimum around the long dry season. Sylvisorex johnstoni remained the dominant species throughout the year. Seasonal variation in trap success of shrews might be related, at least partly, to their reproductive characteristics. Litter size, based on embryo counts, ranged from 1–4 among the species. Breeding occurred throughout the year, but its intensity was lower during the long dry season corresponding with the period of higher ecological constraints for shrews.


2018 ◽  
Vol 6 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Ying-gang Zhu ◽  
Xiao-dan Tang ◽  
Yun-tao Lu ◽  
Jing Zhang ◽  
Jie-ming Qu

AbstractThe prevalence and microbial pattern reported for Community-acquired pneumonia (CAP) differ considerably and contemporary situation remains changing over time. We therefore searched both international and domestic databases for relevant references and pooled incidence of CAP and etiological distribution were estimated separately between children and adults groups. The results showed that CAP remained a major public health issue in China, with a relatively higher incidence than that reported in Western countries. Although pathogens were not detected in nearly half of patients, Mycoplasma pneumoniae remained to be the most frequently detected agent across age groups, the detection yield of which was lower than that reported from other countries. Notably, the incidence of influenza virus A in adults was almost four times higher than that in children while the prevalence of respiratory syncytial virus was much less common in adults than that in children. Despite some limitations, the value of this review, approaching to systematically review grey published data, is to sketch out the contemporary epidemiological and etiological situation of CAP in our country, which could be useful to help policymakers and clinicians make informed choices and to inspire future studies and surveillance.


2020 ◽  
Vol 8 (1) ◽  
pp. 106
Author(s):  
Muhammad Sopiandi Hamdan Kasim ◽  
Baiq Muli Harisanti ◽  
Ali Imran

This study was aimed to determine the identification of macroalgae species in Cemara Beach, Jerowaru District, East Lombok Regency, as the basis for developing biodiversity brochure for public. This is a descriptive explorative  research with sampling technique devided into 4 transects: 1) transect I was in the litoral zone with water conditions that were still quite natural because of lack of influence from the residents; 2) transect II was located in litoral zone near the residential area; 3) transect III was placed in the neritic zone with relatively natural area; and 4) while the transect IV is placed which have same zone as the transect III, but difference by the aquatic environment was directly affected by human activities around the coast. Identification of macroalgae was carried out by in-situ method. Community structure of macroalgae were analyzed using the Shanon-Wiener formula. Based on the results there were found 15 species of macroalgae belonging to the three main divisions namely: Rhodophyta (Red Algae); Phaeophyta (Brown Algae); and Chlorophyta (Green Algae). Based on the results of the validation (graphics, materials, and grammar) by the validator team, concluded that the seaweed diversity brochure was very well qualified without revised so that it was categorized very good for dissemination to public.


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