Effects of season on ecological processes in extensive earthen tilapia ponds in Southeastern Brazil

Abstract In Southeastern Brazil tilapia culture is conducted in extensive and semi-intensive flow-through earthen ponds, being water availability and flow management different in the rainy and dry seasons. In this region lettuce wastes are a potential cheap input for tilapia culture. This study examined the ecological processes developing during the rainy and dry seasons in three extensive flow-through earthen tilapia ponds fertilized with lettuce wastes. Water quality, plankton and sediment parameters were sampled monthly during a year. Factor analysis was used to identify the ecological processes occurring within the ponds and to construct a conceptual graphic model of the pond ecosystem functioning during the rainy and dry seasons. Processes related to nitrogen cycling presented differences between both seasons while processes related to phosphorus cycling did not. Ecological differences among ponds were due to effects of wind protection by surrounding vegetation, organic loading entering, tilapia density and its grazing pressure on zooplankton. Differences in tilapia growth among ponds were related to stocking density and ecological process affecting tilapia food availability and intraspecific competition. Lettuce wastes addition into the ponds did not produce negative effects, thus this practice may be considered a disposal option and a low-cost input source for tilapia, at least at the amounts applied in this study.

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Experimental Setting for Applying Mechanical Stimuli to Study the Endothelial Response of Ex Vivo Vessels under Realistic Pathophysiological Environments

Life ◽

10.3390/life11070671 ◽

2021 ◽

Vol 11 (7) ◽

pp. 671

Author(s):

Ana Osuna ◽

Anna Ulldemolins ◽

Hector Sanz-Fraile ◽

Jorge Otero ◽

Núria Farré ◽

...

Keyword(s):

Ex Vivo ◽

Low Cost ◽

Technical Information ◽

Rabbit Aorta ◽

Pressure Waveform ◽

Mechanical Stimuli ◽

Experimental Setting ◽

Endothelial Response ◽

Flow Through ◽

Open Source Hardware

This paper describes the design, construction and testing of an experimental setting, making it possible to study the endothelium under different pathophysiological conditions. This novel experimental approach allows the application of the following stimuli to an ex vivo vessel in a physiological bath: (a) a realistic intravascular pressure waveform defined by the user; (b) shear stress in the endothelial layer since, in addition to the pressure waveform, the flow through the vessel can be independently controlled by the user; (c) conditions of hypo/hyperoxia and hypo/hypercapnia in an intravascular circulating medium. These stimuli can be applied alone or in different combinations to study possible synergistic or antagonistic effects. The setting performance is illustrated by a proof of concept in an ex vivo rabbit aorta. The experimental setting is easy to build by using very low-cost materials widely available. Online Supplement files provide all the technical information (e.g., circuits, codes, 3D printer drivers) following an open-source hardware approach for free replication.

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An Agent-Based Crop Model Framework for Heterogeneous Soils

Agronomy ◽

10.3390/agronomy11010085 ◽

2021 ◽

Vol 11 (1) ◽

pp. 85

Author(s):

Jorge Lopez-Jimenez ◽

Nicanor Quijano ◽

Alain Vande Wouwer

Keyword(s):

Growth Models ◽

Control Strategies ◽

Low Cost ◽

Soil Heterogeneity ◽

Crop Growth ◽

Negative Effects ◽

Model Framework ◽

Agent Based ◽

Crop Growth Models ◽

Definition Of

Climate change and the efficient use of freshwater for irrigation pose a challenge for sustainable agriculture. Traditionally, the prediction of agricultural production is carried out through crop-growth models and historical records of the climatic variables. However, one of the main flaws of these models is that they do not consider the variability of the soil throughout the cultivation area. In addition, with the availability of new information sources (i.e., aerial or satellite images) and low-cost meteorological stations, it is convenient that the models incorporate prediction capabilities to enhance the representation of production scenarios. In this work, an agent-based model (ABM) that considers the soil heterogeneity and water exchanges is proposed. Soil heterogeneity is associated to the combination of individual behaviours of uniform portions of land (agents), while water fluxes are related to the topography. Each agent is characterized by an individual dynamic model, which describes the local crop growth. Moreover, this model considers positive and negative effects of water level, i.e., drought and waterlogging, on the biomass production. The development of the global ABM is oriented to the future use of control strategies and optimal irrigation policies. The model is built bottom-up starting with the definition of agents, and the Python environment Mesa is chosen for the implementation. The validation is carried out using three topographic scenarios in Colombia. Results of potential production cases are discussed, and some practical recommendations on the implementation are presented.

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Soil Mycobiome Is Shaped by Vegetation and Microhabitats: A Regional-Scale Study in Southeastern Brazil

Journal of Fungi ◽

10.3390/jof7080587 ◽

2021 ◽

Vol 7 (8) ◽

pp. 587

Author(s):

Danielle Hamae Yamauchi ◽

Hans Garcia Garces ◽

Marcus de Melo Teixeira ◽

Gabriel Fellipe Barros Rodrigues ◽

Leila Sabrina Ullmann ◽

...

Keyword(s):

Fungal Community ◽

Vegetation Index ◽

Normalized Difference Vegetation Index ◽

Deciduous Forest ◽

Regional Scale ◽

Southeastern Brazil ◽

Transitional Region ◽

Illumina Platform ◽

Ecological Processes ◽

Life On Earth

Soil is the principal habitat and reservoir of fungi that act on ecological processes vital for life on Earth. Understanding soil fungal community structures and the patterns of species distribution is crucial, considering climatic change and the increasing anthropic impacts affecting nature. We evaluated the soil fungal diversity in southeastern Brazil, in a transitional region that harbors patches of distinct biomes and ecoregions. The samples originated from eight habitats, namely: semi-deciduous forest, Brazilian savanna, pasture, coffee and sugarcane plantation, abandoned buildings, owls’ and armadillos’ burrows. Forty-four soil samples collected in two periods were evaluated by metagenomic approaches, focusing on the high-throughput DNA sequencing of the ITS2 rDNA region in the Illumina platform. Normalized difference vegetation index (NDVI) was used for vegetation cover analysis. NDVI values showed a linear relationship with both diversity and richness, reinforcing the importance of a healthy vegetation for the establishment of a diverse and complex fungal community. The owls’ burrows presented a peculiar fungal composition, including high rates of Onygenales, commonly associated with keratinous animal wastes, and Trichosporonales, a group of basidiomycetous yeasts. Levels of organic matter and copper influenced all guild communities analyzed, supporting them as important drivers in shaping the fungal communities’ structures.

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The use of solar energy for the curing of ferrogeopolymer elements in the semiarid region

MATEC Web of Conferences ◽

10.1051/matecconf/201927601031 ◽

2019 ◽

Vol 276 ◽

pp. 01031 ◽

Cited By ~ 1

Author(s):

Partogi H Simatupang ◽

Petrus Lubalu ◽

Herry L Sianturi ◽

Wilhelmus Bunganaen

Keyword(s):

Solar Energy ◽

Low Cost ◽

Glass Plate ◽

Energy Resource ◽

Semiarid Region ◽

Collector System ◽

Good Potential ◽

Dry Seasons ◽

Wire Meshes ◽

Potential Use

Kupang City in Timor Island of Indonesia, as a semiarid area, has abundant solar energy sources. Based on climatology data of Kupang City in 2013-2015, the minimum and maximum average temperatures in Kupang City range from 19.3-34.8oC. Besides, dry seasons last for about 8 months (April-November). This abundance of solar energy is a potential energy resource for the manufacturing of environmentally friendly ferrogeopolymer elements. Based on previous research, the production of geopolymer material can be done optimally with dry curing treatment at 60-80oC for less than 48 hours. Therefore, in this paper, a low-cost, energy efficient oven operated by a solar energy collector was developed. This paper describes a feasibility study of the use of solar energy for curing ferro-geopolymer elements. The ferro-geopolymer elements made were beams with length 600 mm, width 100 mm and height 100 mm. Wire meshes with 6x6mm of opening were used in 5 layers. The solar energy collector system used as an oven was a zinc coated drum which was painted black outwardly and was covered by a glass plate. Using this oven, it was possible to increase the ambient temperature by 1.62 to 2,37 times. Furthermore, this oven can also increase the flexure strength of ferrogeopolymer elements about ± 25.34%. This paper shows good potential use of solar energy in the manufacturing of ferro-geopolymer elements in the semiarid region.

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Facilitation Effects of Haloxylon salicornicum Shrubs on Associated Understory Annuals, and a Modified “Stress-Gradient” Hypothesis for Droughty Times

Plants ◽

10.3390/plants9121726 ◽

2020 ◽

Vol 9 (12) ◽

pp. 1726

Author(s):

Nasr H. Gomaa ◽

Ahmad K. Hegazy ◽

Arafat Abdel Hamed Abdel Latef

Keyword(s):

Species Richness ◽

Water Availability ◽

Stress Gradient ◽

Growing Season ◽

Annual Species ◽

Negative Effects ◽

Growing Seasons ◽

Dry Seasons ◽

The Impact ◽

Haloxylon Salicornicum

Perennial shrub-annual plant interactions play key roles in desert regions influencing the structure and dynamics of plant communities there. In the present study, carried out in northwestern Saudi Arabia, we examined the effect of Haloxylon salicornicum shrubs on their associated understory annual species across four consecutive growing seasons, along with a record of the seasonal rainfall patterns. We measured density and species richness of all the annual species in permanent quadrats located beneath individual shrubs, as well as in the spaces between shrubs. During wet growing season H. salicornicum shrubs significantly enhanced the density and species richness of sub-canopy species, whereas in the relatively dry seasons they exerted negative effects on the associated species. In all growing seasons, the presence of shrubs was associated with enhanced soil properties, including increased organic carbon content, silt + clay, and levels of nutrients (N, P and K). Shrubs improved soil moisture content beneath their canopies in the wet growing season, while in the dry seasons they had negative effects on water availability. Differences in effects of H. salicornicum on understory plants between growing seasons seem due to the temporal changes in the impact of shrubs on water availability. Our results suggest the facilitative effects of shrubs on sub-canopy annuals in arid ecosystems may switch to negative effects with increasing drought stress. We discuss the study in light of recent refinements of the well-known “stress-gradient hypothesis”.

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Fertilization of Algal Resources By an Exotic Snail May Facilitate Invasion

The UW National Parks Service Research Station Annual Reports ◽

10.13001/uwnpsrc.2003.3555 ◽

2003 ◽

Vol 27 ◽

pp. 116-122

Author(s):

Leslie Riley ◽

Mark Dybdahl ◽

Robert Hall

Keyword(s):

Chlorophyll A ◽

Field Experiments ◽

Gross Primary Production ◽

Nutrient Recycling ◽

Algal Growth ◽

Grazing Pressure ◽

Nitrogen Excretion ◽

Macroinvertebrate Communities ◽

Negative Effects ◽

The Difference

We studied positive and negative effects of snail consumers on their resource to determine if positive consumer effects may be facilitating invasion. Consumer- resource interactions often focus on losses to the resource, even though the resource might benefit if consumers recycle nutrients. The New Zealand mudsnail, Potamopyrgus antipodarum, an exotic in western U.S. rivers, attains high densities and dominates macroinvertebrate communities. In one well-studied river, it consumes the majority of primary productivity, cycles most nitrogen and can grow faster at higher densities. In field experiments, we tested the hypothesis that this invasive grazer stimulates algal growth via nitrogen excretion, which might explain its self-facilitation and invasiveness. Using in-stream cages subdivided into "with snails" and "without snails" sections, we examined the response of periphytic algae to snail grazing and excretion and snail excretion alone at various levels of snail biomass. We found that chlorophyll a and GPP (gross primary production) decreased as the biomass of snails increased in the grazed sections. Snail excretion, in the absence of grazing, increased both chlorophyll a and GPP, demonstrating a positive effect of snails on the resource, consistent with the nutrient recycling and enrichment hypothesis. We found no evidence for increased algal growth at intermediate snail densities in grazed treatments, as predicted by the Herbivore Optimization Curve hypothesis. However, the difference in chlorophyll a between "with snails" and "without snails" treatments increased as snail biomass increased. This suggests that snail compensation of the resource, through excretion, decreases at extremely high levels of grazing pressure and the net effect of snail grazing becomes negative. Together, these results suggest that invasiveness in some rivers may be fostered by this self-facilitation and recycling of essential nutrients.

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Local versus site-level effects of algae on coral microbial communities

Royal Society Open Science ◽

10.1098/rsos.210035 ◽

2021 ◽

Vol 8 (9) ◽

pp. 210035

Author(s):

Amy A. Briggs ◽

Anya L. Brown ◽

Craig W. Osenberg

Keyword(s):

Microbial Communities ◽

Spatial Scales ◽

French Polynesia ◽

Negative Effects ◽

Ecological Processes ◽

Antagonistic Effects ◽

Alpha And Beta Diversity ◽

Macroalgal Cover ◽

Coral Microbiome ◽

Turf Algae

Microbes influence ecological processes, including the dynamics and health of macro-organisms and their interactions with other species. In coral reefs, microbes mediate negative effects of algae on corals when corals are in contact with algae. However, it is unknown whether these effects extend to larger spatial scales, such as at sites with high algal densities. We investigated how local algal contact and site-level macroalgal cover influenced coral microbial communities in a field study at two islands in French Polynesia, Mo'orea and Mangareva. At 5 sites at each island, we sampled prokaryotic microbial communities (microbiomes) associated with corals, macroalgae, turf algae and water, with coral samples taken from individuals that were isolated from or in contact with turf or macroalgae. Algal contact and macroalgal cover had antagonistic effects on coral microbiome alpha and beta diversity. Additionally, coral microbiomes shifted and became more similar to macroalgal microbiomes at sites with high macroalgal cover and with algal contact, although the microbial taxa that changed varied by island. Our results indicate that coral microbiomes can be affected by algae outside of the coral's immediate vicinity, and local- and site-level effects of algae can obscure each other's effects when both scales are not considered.

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Wind Turbine Noise Reduction from Seismological Data

10.5194/egusphere-egu21-4907 ◽

2021 ◽

Author(s):

Janis Heuel ◽

Wolfgang Friederich

Keyword(s):

Signal To Noise Ratio ◽

Low Cost ◽

Computational Cost ◽

Noise Signal ◽

Noise Model ◽

Threshold Function ◽

High Signal ◽

Time Data ◽

Negative Effects ◽

Before And After

Over the last years, installations of wind turbines (WTs) increased worldwide. Owing to negative effects on humans, WTs are often installed in areas with low population density. Because of low anthropogenic noise, these areas are also well suited for sites of seismological stations. As a consequence, WTs are often installed in the same areas as seismological stations. By comparing the noise in recorded data before and after installation of WTs, seismologists noticed a substantial worsening of station quality leading to conflicts between the operators of WTs and earthquake services.In this study, we compare different techniques to reduce or eliminate the disturbing signal from WTs at seismological stations. For this purpose, we selected a seismological station that shows a significant correlation between the power spectral density and the hourly windspeed measurements. Usually, spectral filtering is used to suppress noise in seismic data processing. However, this approach is not effective when noise and signal have overlapping frequency bands which is the case for WT noise. As a first method, we applied the continuous wavelet transform (CWT) on our data to obtain a time-scale representation. From this representation, we estimated a noise threshold function (Langston & Mousavi, 2019) either from noise before the theoretical P-arrival (pre-noise) or using a noise signal from the past with similar ground velocity conditions at the surrounding WTs. Therefore, we installed low cost seismometers at the surrounding WTs to find similar signals at each WT. From these similar signals, we obtain a noise model at the seismological station, which is used to estimate the threshold function. As a second method, we used a denoising autoencoder (DAE) that learns mapping functions to distinguish between noise and signal (Zhu et al., 2019).In our tests, the threshold function performs well when the event is visible in the raw or spectral filtered data, but it fails when WT noise dominates and the event is hidden. In these cases, the DAE removes the WT noise from the data. However, the DAE must be trained with typical noise samples and high signal-to-noise ratio events to distinguish between signal and interfering noise. Using the threshold function and pre-noise can be applied immediately on real-time data and has a low computational cost. Using a noise model from our prerecorded database at the seismological station does not improve the result and it is more time consuming to find similar ground velocity conditions at the surrounding WTs.

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Phylogenetic overdispersion of plant species in southern Brazilian savannas

Brazilian Journal of Biology ◽

10.1590/s1519-69842009000400011 ◽

2009 ◽

Vol 69 (3) ◽

pp. 843-849 ◽

Cited By ~ 6

Author(s):

IA. Silva ◽

MA. Batalha

Keyword(s):

Phylogenetic Relationships ◽

Plant Traits ◽

Environmental Filtering ◽

Southeastern Brazil ◽

Ecological Communities ◽

Ecological Interactions ◽

Ecological Processes ◽

Phylogenetic Structure ◽

History Of ◽

Phylogenetic Overdispersion

Ecological communities are the result of not only present ecological processes, such as competition among species and environmental filtering, but also past and continuing evolutionary processes. Based on these assumptions, we may infer mechanisms of contemporary coexistence from the phylogenetic relationships of the species in a community. We studied the phylogenetic structure of plant communities in four cerrado sites, in southeastern Brazil. We calculated two raw phylogenetic distances among the species sampled. We estimated the phylogenetic structure by comparing the observed phylogenetic distances to the distribution of phylogenetic distances in null communities. We obtained null communities by randomizing the phylogenetic relationships of the regional pool of species. We found a phylogenetic overdispersion of the cerrado species. Phylogenetic overdispersion has several explanations, depending on the phylogenetic history of traits and contemporary ecological interactions. However, based on coexistence models between grasses and trees, density-dependent ecological forces, and the evolutionary history of the cerrado flora, we argue that the phylogenetic overdispersion of cerrado species is predominantly due to competitive interactions, herbivores and pathogen attacks, and ecological speciation. Future studies will need to include information on the phylogenetic history of plant traits.

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