scholarly journals Interhemispheric consistency of scale-dependent spatial variation in the structure of intertidal rocky-shore communities

2018 ◽  
Author(s):  
Alexis Catalán ◽  
Nelson Valdivia ◽  
Ricardo Scrosati
Keyword(s):  
Community Structure ◽  
Spatial Variation ◽  
Spatial Scales ◽  
Vertical Gradient ◽  
Sampling Interval ◽  
Biological Variation ◽  
Rocky Intertidal ◽  
Vertical Variation ◽  
Horizontal Variation ◽  
Sampling Intervals

In rocky intertidal environments, the vertical gradient of abiotic stress generates, directly or indirectly, significant spatial variation in community structure. Along shorelines within biogeographic regions, abiotic changes also generate horizontal biological variation, which when measured at large sampling intervals may surpass vertical biological variation. Little is known, however, on how vertical variation compares with horizontal variation measured at multiple spatial scales in habitats with similar environmental conditions. Here, we compare spatial variability in rocky-intertidal communities between vertical stress gradients and three horizontal spatial scales (sampling interval) across habitats experiencing the same wave exposure on the Northwest Atlantic (NWA) and Southeast Pacific (SEP) coasts. For both regions, the vertical variation in species richness and composition (Raup-Crick and Bray-Curtis indices) was higher than the variation measured at all horizontal scales, from a few cm to hundreds of km. The patterns of variation in community structure matched those of abundance for the dominant sessile organisms, the foundation species Ascophyllum nodosum (seaweed) in NWA and Perumytilus purpuratus (mussel) in SEP. This interhemispheric comparison reveals the tight link between environmental and biological variation, indicating that studies comparing spatial scales of biological variation must consider the underlying environmental variation in addition to simply scale alone.

scholarly journals Interhemispheric consistency of scale-dependent spatial variation in the structure of intertidal rocky-shore communities

2018 ◽  
Author(s):  
Alexis Catalán ◽  
Nelson Valdivia ◽  
Ricardo Scrosati
Keyword(s):  
Community Structure ◽  
Spatial Variation ◽  
Spatial Scales ◽  
Vertical Gradient ◽  
Sampling Interval ◽  
Biological Variation ◽  
Rocky Intertidal ◽  
Vertical Variation ◽  
Horizontal Variation ◽  
Sampling Intervals

In rocky intertidal environments, the vertical gradient of abiotic stress generates, directly or indirectly, significant spatial variation in community structure. Along shorelines within biogeographic regions, abiotic changes also generate horizontal biological variation, which when measured at large sampling intervals may surpass vertical biological variation. Little is known, however, on how vertical variation compares with horizontal variation measured at multiple spatial scales in habitats with similar environmental conditions. Here, we compare spatial variability in rocky-intertidal communities between vertical stress gradients and three horizontal spatial scales (sampling interval) across habitats experiencing the same wave exposure on the Northwest Atlantic (NWA) and Southeast Pacific (SEP) coasts. For both regions, the vertical variation in species richness and composition (Raup-Crick and Bray-Curtis indices) was higher than the variation measured at all horizontal scales, from a few cm to hundreds of km. The patterns of variation in community structure matched those of abundance for the dominant sessile organisms, the foundation species Ascophyllum nodosum (seaweed) in NWA and Perumytilus purpuratus (mussel) in SEP. This interhemispheric comparison reveals the tight link between environmental and biological variation, indicating that studies comparing spatial scales of biological variation must consider the underlying environmental variation in addition to simply scale alone.

scholarly journals Linking spatial patterns of terrestrial herbivore community structure to trophic interactions

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jakub Witold Bubnicki ◽  
Marcin Churski ◽  
Krzysztof Schmidt ◽  
Tom A Diserens ◽  
Dries PJ Kuijper
Keyword(s):  
Spatial Distribution ◽  
Community Structure ◽  
Spatial Variation ◽  
Spatial Scales ◽  
Landscape Scale ◽  
Top Down ◽  
Large Herbivores ◽  
Bottom Up ◽  
Vegetation Heterogeneity ◽  
Herbivore Community

Large herbivores influence ecosystem functioning via their effects on vegetation at different spatial scales. It is often overlooked that the spatial distribution of large herbivores results from their responses to interacting top-down and bottom-up ecological gradients that create landscape-scale variation in the structure of the entire community. We studied the complexity of these cascading interactions using high-resolution camera trapping and remote sensing data in the best-preserved European lowland forest, Białowieża Forest, Poland. We showed that the variation in spatial distribution of an entire community of large herbivores is explained by species-specific responses to both environmental bottom-up and biotic top-down factors in combination with human-induced (cascading) effects. We decomposed the spatial variation in herbivore community structure and identified functionally distinct landscape-scale herbivory regimes (‘herbiscapes’), which are predicted to occur in a variety of ecosystems and could be an important mechanism creating spatial variation in herbivory maintaining vegetation heterogeneity.

scholarly journals Spatial and Temporal Variation in Microbial Diversity and Community Structure in a Contaminated Mangrove Wetland

2020 ◽  
Vol 10 (17) ◽  
pp. 5850
Author(s):  
Jiaojiao Ma ◽  
Ting Zhou ◽  
Chunyu Xu ◽  
Dawen Shen ◽  
Songjun Xu ◽  
...  
Keyword(s):  
Community Structure ◽  
Spatial Variation ◽  
Temporal Variation ◽  
Bacterial Diversity ◽  
Diversity Index ◽  
Total Carbon ◽  
Spatial And Temporal Variation ◽  
Rrna Gene ◽  
Mangrove Wetland ◽  
Mangrove Soils

Field and laboratory investigations were conducted to characterize bacterial diversity and community structure in a badly contaminated mangrove wetland adjacent to the metropolitan area of a megacity in subtropical China. Next-generation sequencing technique was used for sequencing the V4–V5 region of the 16s rRNA gene on the Illumina system. Collectively, Proteobacteria, Chloroflexi, Planctomycetes, Actinobacteria and Bacteroidetes were the predominant phyla identified in the investigated soils. A significant spatial variation in bacterial diversity and community structure was observed for the investigated mangrove soils. Heavy metal pollution played a key role in reducing the bacterial diversity. The spatial variation in soil-borne heavy metals shaped the spatial variation in bacterial diversity and community structure in the study area. Other environmental factors such as total carbon and total nitrogen in the soils that are affected by seasonal change in temperature could also influence the bacterial abundance, diversity and community structure though the temporal variation was relatively weaker, as compared to spatial variation. The bacterial diversity index was lower in the investigated site than in the comparable reference site with less contaminated status. The community structure in mangrove soils at the current study site was, to a remarkable extent, different from those in the tropical mangrove wetlands around the world.

scholarly journals Cerebral CT Perfusion in Acute Stroke: The Effect of Lowering the Tube Load and Sampling Rate on the Reproducibility of Parametric Maps

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1121
Author(s):  
Georgios S. Ioannidis ◽  
Søren Christensen ◽  
Katerina Nikiforaki ◽  
Eleftherios Trivizakis ◽  
Kostas Perisinakis ◽  
...  
Keyword(s):  
Cerebral Blood Volume ◽  
Ct Perfusion ◽  
Sampling Rate ◽  
Volumetric Analysis ◽  
Sampling Interval ◽  
Diagnostic Efficiency ◽  
Temporal Sampling ◽  
Sampling Intervals ◽  
The Mean ◽  
Parametric Maps

The aim of this study was to define lower dose parameters (tube load and temporal sampling) for CT perfusion that still preserve the diagnostic efficiency of the derived parametric maps. Ninety stroke CT examinations from four clinical sites with 1 s temporal sampling and a range of tube loads (mAs) (100–180) were studied. Realistic CT noise was retrospectively added to simulate a CT perfusion protocol, with a maximum reduction of 40% tube load (mAs) combined with increased sampling intervals (up to 3 s). Perfusion maps from the original and simulated protocols were compared by: (a) similarity using a voxel-wise Pearson’s correlation coefficient r with in-house software; (b) volumetric analysis of the infarcted and hypoperfused volumes using commercial software. Pearson’s r values varied for the different perfusion metrics from 0.1 to 0.85. The mean slope of increase and cerebral blood volume present the highest r values, remaining consistently above 0.7 for all protocol versions with 2 s sampling interval. Reduction of the sampling rate from 2 s to 1 s had only modest impacts on a TMAX volume of 0.4 mL (IQR −1–3) (p = 0.04) and core volume of −1.1 mL (IQR −4–0) (p < 0.001), indicating dose savings of 50%, with no practical loss of diagnostic accuracy. The lowest possible dose protocol was 2 s temporal sampling and a tube load of 100 mAs.

scholarly journals Archaeal ammonia oxidizers respond to soil factors at smaller spatial scales than the overall archaeal community does in a high Arctic polar oasis

2016 ◽  
Vol 62 (6) ◽  
pp. 485-491 ◽  
Author(s):  
Samiran Banerjee ◽  
Nabla Kennedy ◽  
Alan E. Richardson ◽  
Keith N. Egger ◽  
Steven D. Siciliano
Keyword(s):  
Community Structure ◽  
Spatial Scales ◽  
Archaeal Community ◽  
Diversity Indices ◽  
High Arctic ◽  
Total Carbon ◽  
Spatial Dependency ◽  
Edaphic Factors ◽  
Total Carbon Content ◽  
Arctic Soils

Archaea are ubiquitous and highly abundant in Arctic soils. Because of their oligotrophic nature, archaea play an important role in biogeochemical processes in nutrient-limited Arctic soils. With the existing knowledge of high archaeal abundance and functional potential in Arctic soils, this study employed terminal restriction fragment length polymorphism (t-RFLP) profiling and geostatistical analysis to explore spatial dependency and edaphic determinants of the overall archaeal (ARC) and ammonia-oxidizing archaeal (AOA) communities in a high Arctic polar oasis soil. ARC communities were spatially dependent at the 2–5 m scale (P < 0.05), whereas AOA communities were dependent at the ∼1 m scale (P < 0.0001). Soil moisture, pH, and total carbon content were key edaphic factors driving both the ARC and AOA community structure. However, AOA evenness had simultaneous correlations with dissolved organic nitrogen and mineral nitrogen, indicating a possible niche differentiation for AOA in which dry mineral and wet organic soil microsites support different AOA genotypes. Richness, evenness, and diversity indices of both ARC and AOA communities showed high spatial dependency along the landscape and resembled scaling of edaphic factors. The spatial link between archaeal community structure and soil resources found in this study has implications for predictive understanding of archaea-driven processes in polar oases.

scholarly journals The effect of sampling interval on the predictions of an asperity contact model of two-process surfaces

2017 ◽  
Vol 65 (3) ◽  
pp. 391-398 ◽  
Author(s):  
P. Pawlus ◽  
R. Reizer ◽  
M. Wieczorowski ◽  
W. Żelasko
Keyword(s):  
Surface Region ◽  
Sampling Interval ◽  
Plasticity Index ◽  
Contact Model ◽  
Asperity Contact ◽  
Normal Contact ◽  
Method Of Calculation ◽  
Surface Separation ◽  
Sampling Intervals ◽  
Flat Steel

AbstractContact of random machined two-process steel textures with a smooth, flat steel surface is discussed in this paper. Two-process surfaces were machined by vapour blasting followed by lapping. An elastic-plastic contact model was applied, assuming distributed radius of asperities. Calculation procedures allowed the mean surface separation, contact pressure, and area fraction to be computed as functions of sampling intervals. Parameters characterizing the summits important in contact mechanics were calculated for different sampling intervals. Plasticity index of two-process textures was calculated using the modified procedure. It was found that the influence of sampling interval on normal contact depended on the rough surface ability to plastic deformation. The use of a traditional method of calculation overestimated the plasticity index. Peaks from plateau surface region governed contact characteristics of two-process surfaces.

scholarly journals Temporal Distribution of Gastropods In Rocky Intertidal Area In North Manokwari, West Papua

2019 ◽  
pp. 1
Author(s):  
Dandi Saleky ◽  
Simon P.O Leatemia ◽  
Yuanike Yuanike ◽  
Irman Rumengan ◽  
I Nyoman Giri Putra
Keyword(s):  
Community Structure ◽  
Distribution Pattern ◽  
Similarity Index ◽  
Temporal Distribution ◽  
Population History ◽  
Rocky Intertidal ◽  
Systematic Sampling ◽  
Intertidal Area ◽  
Ecological Features ◽  
West Papua

Gastropods is an important organism that commonly found inhabiting the rocky intertidal area. Distribution pattern of this species is influenced by various factors such as population history, microhabitat, predation and a complex interactions between oceanographic dynamics and ecological features. This study aims to compare the temporal distribution pattern of gastropods at two different rocky intertidal area. This research was conducted at the rocky intertidal area of Amban and Nuni, North Manokwari District, West Papua. Data collection was performed during the daylight and night in April and June 2012 using systematic sampling method. The results showed that both physical and chemical factors are suite for supporting gastropods life. Furthermore, these factors seem to have an impact on gastropod zoning patterns observed in the study area. The similarity index values ​​indicate that the similarity of gastropod species between the two locations is low, which means that the species of gastropods found in each location is quite different. The community structure of gastropod at the study area is stable. In addition, we found that the gastropods diversity were higher during the night than the daylight because gastropods are classified as a nocturnal animals. Key Words: Gastropod; Rocky Intertidal; Community Structure; Nocturnal

scholarly journals Spatial analysis of phylogenetic community structure: New version of a classical method

2015 ◽  
Author(s):  
Carlo Ricotta ◽  
Eszter EA Ari ◽  
Giuliano Bonanomi ◽  
Francesco Giannino ◽  
Duncan Heathfield ◽  
...  
Keyword(s):  
Community Structure ◽  
Spatial Scales ◽  
Point Pattern ◽  
Maximum Deviation ◽  
Individual Plant ◽  
Phylogenetic Distance ◽  
Phylogenetic Structure ◽  
Phylogenetic Community Structure ◽  
Point Patterns ◽  
Wide Range

The increasing availability of phylogenetic information facilitates the use of evolutionary methods in community ecology to reveal the importance of evolution in the species assembly process. However, while several methods have been applied to a wide range of communities across different spatial scales with the purpose of detecting non-random phylogenetic patterns, the spatial aspects of phylogenetic community structure have received far less attention. Accordingly, the question for this study is: can point pattern analysis be used for revealing the phylogenetic structure of multi-species assemblages? We introduce a new individual-centered procedure for analyzing the scale-dependent phylogenetic structure of multi-species point patterns based on digitized field data. The method uses nested circular plots with increasing radii drawn around each individual plant and calculates the mean phylogenetic distance between the focal individual and all individuals located in the circular ring delimited by two successive radii. This scale-dependent value is then averaged over all individuals of the same species and the observed mean is compared to a null expectation with permutation procedures. The method detects particular radius values at which the point pattern of a single species exhibits maximum deviation from the expectation towards either phylogenetic aggregation or segregation. Its performance is illustrated using data from a grassland community in Hungary and simulated point patterns. The proposed method can be extended to virtually any distance function for species pairs, such as functional distances.

scholarly journals Spatiotemporal variability of NO<sub>2</sub> and PM<sub>2.5</sub> over Eastern China: observational and model analyses with a novel statistical method

2018 ◽  
Vol 18 (17) ◽  
pp. 12933-12952 ◽  
Author(s):  
Mengyao Liu ◽  
Jintai Lin ◽  
Yuchen Wang ◽  
Yang Sun ◽  
Bo Zheng ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Eastern China ◽  
Ground Level ◽  
Vertical Gradient ◽  
Spatiotemporal Variability ◽  
Model Errors ◽  
Diurnal Variability ◽  
Near Surface ◽  
Synchronous Mode ◽  
The North

Abstract. Eastern China (27–41∘ N, 110–123∘ E) is heavily polluted by nitrogen dioxide (NO2), particulate matter with aerodynamic diameter below 2.5 µm (PM2.5), and other air pollutants. These pollutants vary on a variety of temporal and spatial scales, with many temporal scales that are nonperiodic and nonstationary, challenging proper quantitative characterization and visualization. This study uses a newly compiled EOF–EEMD analysis visualization package to evaluate the spatiotemporal variability of ground-level NO2, PM2.5, and their associations with meteorological processes over Eastern China in fall–winter 2013. Applying the package to observed hourly pollutant data reveals a primary spatial pattern representing Eastern China synchronous variation in time, which is dominated by diurnal variability with a much weaker day-to-day signal. A secondary spatial mode, representing north–south opposing changes in time with no constant period, is characterized by wind-related dilution or a buildup of pollutants from one day to another. We further evaluate simulations of nested GEOS-Chem v9-02 and WRF/CMAQ v5.0.1 in capturing the spatiotemporal variability of pollutants. GEOS-Chem underestimates NO2 by about 17 µg m−3 and PM2.5 by 35 µg m−3 on average over fall–winter 2013. It reproduces the diurnal variability for both pollutants. For the day-to-day variation, GEOS-Chem reproduces the observed north–south contrasting mode for both pollutants but not the Eastern China synchronous mode (especially for NO2). The model errors are due to a first model layer too thick (about 130 m) to capture the near-surface vertical gradient, deficiencies in the nighttime nitrogen chemistry in the first layer, and missing secondary organic aerosols and anthropogenic dust. CMAQ overestimates the diurnal cycle of pollutants due to too-weak boundary layer mixing, especially in the nighttime, and overestimates NO2 by about 30 µg m−3 and PM2.5 by 60 µg m−3. For the day-to-day variability, CMAQ reproduces the observed Eastern China synchronous mode but not the north–south opposing mode of NO2. Both models capture the day-to-day variability of PM2.5 better than that of NO2. These results shed light on model improvement. The EOF–EEMD package is freely available for noncommercial uses.

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