scholarly journals EFFECTS OF ENVIRONMENTAL FEATURES ON FISH ASSEMBLAGE STRUCTURES IN THE MACHADO RIVER, AMAZON BASIN, BRAZIL

2021 ◽  
Vol 9 (1) ◽  
pp. 52-65
Author(s):  
Raniere Sousa ◽  
Alexandro Florentino ◽  
Rodrigo Amaral ◽  
Severino Lima
Keyword(s):  
Amazon Basin ◽  
Fish Assemblages ◽  
Abiotic Factors ◽  
Fish Communities ◽  
Chemical Properties ◽  
Abundant Species ◽  
Explanatory Variables ◽  
Physiochemical Parameters ◽  
Small Streams ◽  
Significant Difference

In this study, we examined the influence of the environmental characteristics of three microbasins of the Machado River on the distribution of fish assemblages in order to predict if its fish communities are influenced by abiotic factors. Sampling was conducted in first order streams in the microbasins of the Machado River, state of Rondônia, Brazil. In each stream, we selected two 150 m-long stretches on the main channel. The fish were sampled with different sizes of nets, stored in plastic bags, and taxonomically identified. At each site, the physiochemical parameters of the water (temperature, dissolved oxygen, pH, and electrical conductivity) were measured. Thus, abundance, richness and Hill’s diversity were estimated. The Permutational Multivariate Analysis of Variance (Permanova) was applied to determine the effect in fish abundance, richness and diversity, considering microbasins, physio-chemical water and seasons as explanatory variables. A distance-based redundancy analysis (dbRDA)was performed to determine the influence of physio-chemical properties of the water across the three microbasins and their effect on fish composition. We sampled a total of 6,432 individuals belonging to 4 orders, 19 families, and 56 species. Aequidens tetramerus, Serrapinnus cff. microdon and Serrapinnus aff. notomelas were the most abundant species. Conductivity was the only explanatory variable in which a significant difference was detected for the three response variables. The dbRDA indicated that 44.57% of the total variance was explained by the variables used and were significantly correlated with the abundance and composition of the ichthyofauna (F = 1.88, p = 0.035), conductivity and pH were the most relevant factors. A significant association between fish communities and abiotic factors supports the hypothesis that broad-scale patterns in fish communities in Amazonian small streams are, at least in part, structured by abiotic conditions.

What controls who is where in freshwater fish communities – the roles of biotic, abiotic, and spatial factors

2001 ◽  
Vol 58 (1) ◽  
pp. 157-170 ◽  
Author(s):  
Donald A Jackson ◽  
Pedro R Peres-Neto ◽  
Julian D Olden
Keyword(s):  
Large Scale ◽  
Abiotic Factors ◽  
Fish Communities ◽  
Geographic Region ◽  
Dominant Factor ◽  
Small Scale ◽  
Spatial Factors ◽  
Small Streams ◽  
Lake Systems ◽  
The Impact

We examine evidence for the structuring of fish communities from stream and lake systems and the roles of biotic, abiotic, and spatial factors in determining the species composition. Piscivory by fish is a dominant factor in both stream and lake systems whereas evidence for the importance of competition appears less convincing. Within small streams or lakes, the impact of predation may exclude other species, thereby leading to mutually exclusive distributions and strong differences in community composition. Within a geographic region, abiotic effects frequently dictate the relative importance of piscivory, thereby indirectly influencing the composition of prey species present. The spatial scale of studies influences our perceived importance of biotic versus abiotic factors, with small-scale studies indicating a greater importance of competition and large-scale studies emphasizing abiotic controls. The scale of the individual sites considered is critical because smaller systems have higher variability and wider extremes of conditions than larger lakes and rivers. The stability of physical systems and degree of spatial connectivity contribute to increased diversity in both larger stream and larger lake systems. We identify challenges and needs that must be addressed both to advance the field of fish community ecology and to face the problems associated with human-induced changes.

scholarly journals Impacts of Climate Change Interacting Abiotic Factors on Growth, aflD and aflR Gene Expression and Aflatoxin B1 Production by Aspergillus flavus Strains In Vitro and on Pistachio Nuts

Toxins ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 385
Author(s):  
Alaa Baazeem ◽  
Alicia Rodriguez ◽  
Angel Medina ◽  
Naresh Magan
Keyword(s):  
Climate Change ◽  
Gene Expression ◽  
Water Stress ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Abiotic Factors ◽  
Pistachio Nuts ◽  
Significant Difference ◽  
Spoilage Fungi

Pistachio nuts are an important economic tree nut crop which is used directly or processed for many food-related activities. They can become colonized by mycotoxigenic spoilage fungi, especially Aspergillus flavus, mainly resulting in contamination with aflatoxins (AFs), especially aflatoxin B1 (AFB1). The prevailing climate in which these crops are grown changes as temperature and atmospheric CO2 levels increase, and episodes of extreme wet/dry cycles occur due to human industrial activity. The objectives of this study were to evaluate the effect of interacting Climate Change (CC)-related abiotic factors of temperature (35 vs. 37 °C), CO2 (400 vs. 1000 ppm), and water stress (0.98–0.93 water activity, aw) on (a) growth (b) aflD and aflR biosynthetic gene expression and (c) AFB1 production by two strains A. flavus (AB3, AB10) in vitro on milled pistachio-based media and when colonizing layers of shelled raw pistachio nuts. The A. flavus strains were resilient in terms of growth on pistachio-based media and the colonisation of pistachio nuts with no significant difference when exposed to the interacting three-way climate-related abiotic factors. However, in vitro studies showed that AFB1 production was significantly stimulated (p < 0.05), especially when exposed to 1000 ppm CO2 at 0.98–0.95 aw and 35 °C, and sometimes in the 37 °C treatment group at 0.98 aw. The relative expression of the structural aflD gene involved in AFB1 biosynthesis was decreased or only slightly increased, relative to the control conditions at elevated CO, regardless of the aw level examined. For the regulatory aflR gene expression, there was a significant (p < 0.05) increase in 1000 ppm CO2 and 37 °C for both strains, especially at 0.95 aw. The in situ colonization of pistachio nuts resulted in a significant (p < 0.05) stimulation of AFB1 production at 35 °C and 1000 ppm CO2 for both strains, especially at 0.98 aw. At 37 °C, AFB1 production was either decreased, in strain AB3, or remained similar, as in strain AB10, when exposed to 1000 ppm CO2. This suggests that CC factors may have a differential effect, depending on the interacting conditions of temperature, exposure to CO2 and the level of water stress on AFB1 production.

scholarly journals Responses of Bat Communities (Mammalia: Chiroptera) to Forest Loss and Habitat Conversion in Southern Cameroon

2021 ◽  
Vol 14 ◽  
pp. 194008292110103
Author(s):  
Patrick Jules Atagana ◽  
Eric Moïse Bakwo Fils ◽  
Sevilor Kekeunou
Keyword(s):  
Secondary Forest ◽  
Biosphere Reserve ◽  
Abundant Species ◽  
Primary Forest ◽  
Habitat Types ◽  
Habitat Transformation ◽  
Significant Difference ◽  
Southern Cameroon ◽  
Habitat Conversion ◽  
Species Specific

We aimed to assess how bats are affected by habitat transformation by comparing bat assemblages in four habitat types: primary forest, secondary forest, cocoa plantations and human habitations in the Dja Biosphere Reserve of southern Cameroon. Bats were sampled in the four habitat types using mist nets. During 126 nights, a total of 413 bats were captured, belonging to four families, 16 genera and 24 species. Ninety three individuals (17 species) were captured in the primary forest, followed by plantations (105 individuals, 14 species), human habitations (159 individuals, 10 species), and secondary forest (55 individuals, eight species). Megaloglossus woermanni was recorded in all the four habitats, and was the most abundant species (105 individuals). The analysis of bat assemblage between habitat types showed a statistically significant difference in species composition. The distribution of the six most abundant species ( Epomops franqueti, Megaloglossus woermanni, Rousettus aegyptiacus, Dohyrina cyclops, Hipposideros cf. caffer and Hipposideros cf. ruber) was influenced by habitat types. Our results suggest that the decrease in species richness observed in disturbed habitats may be due to habitat perturbations of primary forest habitats. Therefore, it is important to examine the effects of habitat conversion at species level, as responses are often species-specific.

Heterogeneity of macrophyte banks affects the structure of fish communities in flooded habitats of the Amazon Basin

2021 ◽  
Vol 55 (1) ◽  
pp. 215-226
Author(s):  
Flávia Alessandra Silva Nonato ◽  
Thaisa Sala Michelan ◽  
Pâmela Virgolino Freitas ◽  
Calebe Maia ◽  
Luciano Fogaça de Assis Montag
Keyword(s):  
Amazon Basin ◽  
Fish Communities

scholarly journals Shellfish Chitosan Potential in Wine Clarification

2021 ◽  
Vol 11 (10) ◽  
pp. 4417
Author(s):  
Veronica Vendramin ◽  
Gaia Spinato ◽  
Simone Vincenzi
Keyword(s):  
Molecular Structure ◽  
Chemical Properties ◽  
Allergic Reactions ◽  
Chitin Content ◽  
Deacetylation Degree ◽  
Physical Chemical ◽  
Similar Chemical ◽  
Fungal Chitosan ◽  
Significant Difference ◽  
Fish Industry

Chitosan is a chitin-derived fiber, extracted from the shellfish shells, a by-product of the fish industry, or from fungi grown in bioreactors. In oenology, it is used for the control of Brettanomyces spp., for the prevention of ferric, copper, and protein casse and for clarification. The International Organisation of Vine and Wine established the exclusive utilization of fungal chitosan to avoid the eventuality of allergic reactions. This work focuses on the differences between two chitosan categories, fungal and animal chitosan, characterizing several samples in terms of chitin content and degree of deacetylation. In addition, different acids were used to dissolve chitosans, and their effect on viscosity and on the efficacy in wine clarification were observed. The results demonstrated that even if fungal and animal chitosans shared similar chemical properties (deacetylation degree and chitin content), they showed different viscosity depending on their molecular weight but also on the acid used to dissolve them. A significant difference was discovered on their fining properties, as animal chitosans showed a faster and greater sedimentation compared to the fungal ones, independently from the acid used for their dissolution. This suggests that physical–chemical differences in the molecular structure occur between the two chitosan categories and that this significantly affects their technologic (oenological) properties.

scholarly journals Comparison of predicted psychological distress among workers between artificial intelligence and psychiatrists: a cross-sectional study in Tsukuba Science City, Japan

BMJ Open ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. e046265
Author(s):  
Shotaro Doki ◽  
Shinichiro Sasahara ◽  
Daisuke Hori ◽  
Yuichi Oi ◽  
Tsukasa Takahashi ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Intelligence ◽  
Psychological Distress ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Explanatory Variables ◽  
The Neural Network ◽  
Significant Difference ◽  
Total Data

ObjectivesPsychological distress is a worldwide problem and a serious problem that needs to be addressed in the field of occupational health. This study aimed to use artificial intelligence (AI) to predict psychological distress among workers using sociodemographic, lifestyle and sleep factors, not subjective information such as mood and emotion, and to examine the performance of the AI models through a comparison with psychiatrists.DesignCross-sectional study.SettingWe conducted a survey on psychological distress and living conditions among workers. An AI model for predicting psychological distress was created and then the results were compared in terms of accuracy with predictions made by psychiatrists.ParticipantsAn AI model of the neural network and six psychiatrists.Primary outcomeThe accuracies of the AI model and psychiatrists for predicting psychological distress.MethodsIn total, data from 7251 workers were analysed to predict moderate and severe psychological distress. An AI model of the neural network was created and accuracy, sensitivity and specificity were calculated. Six psychiatrists used the same data as the AI model to predict psychological distress and conduct a comparison with the AI model.ResultsThe accuracies of the AI model and psychiatrists for predicting moderate psychological distress were 65.2% and 64.4%, respectively, showing no significant difference. The accuracies of the AI model and psychiatrists for predicting severe psychological distress were 89.9% and 85.5%, respectively, indicating that the AI model had significantly higher accuracy.ConclusionsA machine learning model was successfully developed to screen workers with depressed mood. The explanatory variables used for the predictions did not directly ask about mood. Therefore, this newly developed model appears to be able to predict psychological distress among workers easily, regardless of their subjective views.

scholarly journals Diversity of Epibionts Associated with Lepidochelys olivacea (Eschscholtz 1829) Sea Turtles Nesting in the Mexican South Pacific

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1734
Author(s):  
Brenda Sarahí Ramos-Rivera ◽  
Himmer Castro-Mondragon ◽  
José Gabriel Kuk-Dzul ◽  
Pedro Flores-Rodríguez ◽  
Rafael Flores-Garza
Keyword(s):  
Data Analysis ◽  
Sea Turtles ◽  
South Pacific ◽  
First Record ◽  
Abundant Species ◽  
Interspecific Relationships ◽  
Lepidochelys Olivacea ◽  
Significant Difference ◽  
The Relationship ◽  
Head Neck

The present study contributes to the knowledge of epibionts recorded on sea turtles that nested on a beach in the South Pacific of Mexico. A total of 125 Lepidochelys olivacea turtles nested on Llano Real beach, Guerrero, Mexico, were examined. We collected 450 conspicuous organisms from 8 species from 43 turtles. The corresponding data analysis was carried out to obtain the relative abundance, the relationship between turtle sizes and the presence of organisms, the similarity of species between the sampling months, and the interspecific relationships between the epibionts and the turtles observed. Chelonibia testudinaria was the most abundant species, while Remora remora was the least abundant species. The turtles were divided into six body sections, with the greatest abundance of these organisms located in the head–neck section of turtles, and there was a significant difference in the size of the turtles that presented epibionts and those that did not. C. testudinaria showed greater similarity between sampling months, and the interspecific relationships recorded were commensalism, parasitism, amensalism, and protocooperation. This research contributes the first record of epibionts in L. olivacea nesting in Guerrero, Mexico.

scholarly journals Effect of Mosses on physical and chemical properties of soil in temperate forests of Garhwal Himalayas

2021 ◽  
pp. 1-10
Author(s):  
Anshu Siwach ◽  
Siddhartha Kaushal ◽  
Ratul Baishya
Keyword(s):  
Physical Properties ◽  
Chemical Properties ◽  
Nutrient Status ◽  
High Rate ◽  
Physical And Chemical Properties ◽  
Garhwal Himalayas ◽  
Forest Sites ◽  
Significant Difference ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract Mosses are one of the most important and dominant plant communities, especially in the temperate biome, and play a significant role in ecosystem function and dynamics. They influence the water, energy and element cycle due to their unique ecology and physiology. The present study was undertaken in three different temperate forest sites in the Garhwal Himalayas, viz., Triyuginarayan (Kedarnath Wildlife Sanctuary (KWLS)), Chakrata, and Kanasar forest range. The study was focused on understanding the influence of mosses on soil physical properties and nutrient availability. Different physico-chemical properties were analysed under two different substrata, that is, with and without moss cover in two different seasons, viz., monsoon and winter. We observed mosses to influence and alter the physical properties and nutrient status of soil in both seasons. All soil physical and chemical properties, except magnesium, showed significant difference within the substrates, among all the sites and across the two seasons. Besides the soil characteristics underneath the moss vegetation, the study also highlights the diversity of mosses found in the area. Mosses appear to create high nutrient microsites via a high rate of organic matter accumulation and retain nutrients for longer periods thus, maintaining ecosystem stability.

scholarly journals Fate of hydrocarbon pollutants in source and non-source control sustainable drainage systems

2013 ◽  
Vol 69 (4) ◽  
pp. 703-709 ◽  
Author(s):  
Georgios Roinas ◽  
Cath Mant ◽  
John B. Williams
Keyword(s):  
Organic Pollutants ◽  
Chemical Properties ◽  
Pollutant Removal ◽  
Total Petroleum Hydrocarbons ◽  
Source Control ◽  
Storm Events ◽  
Pollutant Loads ◽  
Significant Difference ◽  
Local Roads ◽  
Polycyclic Aromatic

Sustainable drainage (SuDs) is an established method for managing runoff from developments, and source control is part of accepted design philosophy. However, there are limited studies into the contribution source control makes to pollutant removal, especially for roads. This study examines organic pollutants, total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs), in paired source and non-source control full-scale SuDs systems. Sites were selected to cover local roads, trunk roads and housing developments, with a range of SuDs, including porous asphalt, swales, detention basins and ponds. Soil and water samples were taken bi-monthly over 12 months to assess pollutant loads. Results show first flush patterns in storm events for solids, but not for TPH. The patterns of removal for specific PAHs were also different, reflecting varying physico-chemical properties. The potential of trunk roads for pollution was illustrated by peak runoff for TPH of &gt; 17,000 μg/l. Overall there was no significant difference between pollutant loads from source and non-source control systems, but the dynamic nature of runoff means that longer-term data are required. The outcomes of this project will increase understanding of organic pollutants behaviour in SuDs. This will provide design guidance about the most appropriate systems for treating these pollutants.

scholarly journals Capture efficiency for small dominant mesozooplankters (Copepoda, Appendicularia) off Buenos Aires Province (34ºS-41ºS), Argentine Sea, using two plankton mesh sizes

2009 ◽  
Vol 57 (3) ◽  
pp. 205-214 ◽  
Author(s):  
Rosana Di Mauro ◽  
Fabiana Capitanio ◽  
María Delia Viñas
Keyword(s):  
Buenos Aires ◽  
Developmental Stages ◽  
Fish Larvae ◽  
Abundant Species ◽  
Accurate Estimation ◽  
Buenos Aires Province ◽  
Oikopleura Dioica ◽  
Great Loss ◽  
Argentine Sea ◽  
Significant Difference

Two plankton mesh sizes of 67 µm and 220 µm were compared to evaluate their efficiency in the capture of the smallest copepods and appendicularians present in the Buenos Aires coastal area (Argentine Sea). A total of 12 copepod species and one appendicularian species were recorded in this study. The copepods were separated into 4 groups: harpacticoids, cyclopoids, small calanoids and large calanoids and their developmental stages. Among the cyclopoids, Oithona nana was the most abundant species, being 96.29 % underestimated by the 220 µm mesh, whereas Microsetella norvegica dominated the harpacticoids and was captured exclusively by the smaller mesh. Similar results were found for copepodites I-III of small calanoids, whose net sampled underestimation reached 99.70%. On the other hand, no significant difference between meshes was found for adults and copepodites IV-V of small calanoids or any of the developmental stages of large calanoids. A great loss of biomass was observed for O. nana when applying the larger mesh. In regards to the appendicularian Oikopleura dioica, all size ranges below 1,000 µm length were better estimated by the 67 µm mesh in terms of abundance and biomass. Our results clearly show that the 67 µm mesh was more efficient in the capture of early stages of small copepods thus providing a more accurate estimation of the fish larvae prey field.

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