Coupled effects of landscape structures and water chemistry on bacterioplankton communities at multi-spatial scales

2021 ◽  
pp. 151350
Author(s):  
Wang Shu ◽  
Peng Wang ◽  
Qiyu Xu ◽  
Ting Zeng ◽  
Minjun Ding ◽  
...  
Keyword(s):  
Water Chemistry ◽  
Spatial Scales ◽  
Bacterioplankton Communities

scholarly journals Impact of Landscape Attributes on Surface Water in the Tiber River Basin (Central Italy)

Proceedings ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 11
Author(s):  
Gozzi ◽  
Dakos ◽  
Trevisani ◽  
Buccianti ◽  
Graziano ◽  
...  
Keyword(s):  
Surface Water ◽  
Water Chemistry ◽  
River Basin ◽  
Spatial Scales ◽  
Sampling Site ◽  
Central Italy ◽  
Geographical Information ◽  
Major Influence ◽  
Compositional Data Analysis ◽  
Tiber River

River catchments are highly complex systems characterized by several properties such as self-organization, multi-scale variability, hydraulic and topographic gradients, patchiness and heterogeneity, resilience and a hierarchical structure. These features, coupled with several geomorphological, anthropogenic and climatic drivers, are expected to influence the surface water composition over different temporal and spatial scales. The knowledge of these complex interlinks plays a key role in both river basin management and predictability to potential pollution events. Nevertheless, due to the considerable amount of factors involved in the analysis, the unique combination of attributes characterizing each catchment and the lack of data at an adequate scale, it still remains unclear which of the environmental parameters have a major influence on the water chemistry. In this work, the hierarchy of the variability in the chemical composition of 160 water samples collected in 2017 throughout the Tiber River Basin, the largest catchment in Central Italy (17,156 km2), was explored. The results obtained by using advanced statistical methods, including the Compositional Data Analysis, highlighted different sources of variability linked to the geological (low variability) and anthropogenic origin (high variability) of the main solutes. Furthermore, for each sampling site, the corresponding watershed was calculated from the Digital Terrain Model using a Geographical Information System-based elaboration. The aim was to evaluate the relationships between the landscape morphological properties of the watersheds, such as elevation, drainage area, slope or other morphometric indexes and the physical-chemical parameters of the river waters on the basis of different geological and topographical settings of the basin. The outcomes proved to be particularly useful to discriminate between water chemistry mainly influenced by surface run-off processes and that affected by ground water circulation.

scholarly journals Broad-scale spatial patterns of canopy cover and pond morphology affect the structure of a Neotropical amphibian metacommunity

2013 ◽  
Author(s):  
Diogo B. Provete ◽  
Thiago Gonçalves-Souza ◽  
Michel Garey ◽  
Itamar A. Martins ◽  
Denise Rossa-Feres
Keyword(s):  
Species Composition ◽  
Water Chemistry ◽  
Spatial Patterns ◽  
Site Selection ◽  
Spatial Scales ◽  
Canopy Cover ◽  
Breeding Site ◽  
Larval Anurans ◽  
Metacommunity Structure ◽  
Broad Scale

Spatial and environmental processes influence species composition at distinct scales. Previous studies suggested that the landscape-scale distribution of larval anurans is influenced by environmental gradients related to adult breeding site selection, such as pond canopy cover, but not water chemistry. However, the combined effects of spatial, pond morphology, and water chemistry variables on metacommunity structure of larval anurans have not been analyzed. We used a partial redundancy analysis with variation partitioning to analyze the relative influence of pond morphology (e.g., depth, area, and aquatic vegetation), water chemistry, and spatial variables on a tadpole metacommunity from southeastern Brazil. We predict that the metacommunity will be spatially structured at broad spatial scales, while environmental variables, mainly related to adult habitat selection, would play a larger role at fine spatial scales. We found that broad-scale spatial patterns of pond canopy cover and pond morphology strongly influenced metacommunity structure. Additionally, species composition was spatially autocorrelated at short distances. We suggest that the reproductive behavior of adult anurans is driving tadpole metacommunity dynamics, since pond morphology, but not water chemistry affects breeding site selection by adults. Our results contribute to the understanding of amphibian species diversity in tropical environments.

Seasonal and spatial distribution and assembly processes of bacterioplankton communities in a subtropical urban river

2020 ◽  
Vol 96 (9) ◽  
Author(s):  
Wang Shu ◽  
Peng Wang ◽  
Hua Zhang ◽  
Mingjun Ding ◽  
Bobo Wu
Keyword(s):  
Water Chemistry ◽  
Stochastic Processes ◽  
Flow Rate ◽  
Community Dynamics ◽  
Environmental Changes ◽  
Urban River ◽  
Alpha And Beta Diversity ◽  
The Core ◽  
Deterministic Processes ◽  
Bacterioplankton Communities

ABSTRACT The ecological functions of core and non-core bacteria are gradually being identified, yet little is known about their responses to environmental changes and assembly processes, especially in urban river ecosystems. Here, we investigated bacterioplankton communities over 1 year in an urban section of the Ganjiang River, China. The results revealed that the alpha- and beta-diversity of bacterioplankton communities had no significant spatial differences along the urbanization gradient, but they presented distinct seasonal variations. The bacterioplankton communities were comprised of a few core taxa (11.8%) and a large number of non-core taxa (88.2%), of which the non-core taxa were the most active component responsible for community dynamics. Most non-core taxa (76.84%) belonged to non-typical freshwater bacteria, implying that they are more likely to derive from allochthonous inputs than the core taxa. Variance partitioning analyses showed that air temperature, flow rate and water chemistry together explained 58.2 and 38.9% of the variations of the core taxa and non-core taxa, respectively. In addition, the relative importance of temperature and water chemistry on the bacterioplankton communities prevailed over that of flow rate alone. This means that deterministic processes and stochastic processes simultaneously control the bacterioplankton community assembly, with deterministic processes contributing more than stochastic processes.

scholarly journals Diverse Early Life-History Strategies in Migratory Amazonian Catfish: Implications for Conservation and Management

2015 ◽  
Author(s):  
Jens C Hegg ◽  
Tommaso Giarrizzo ◽  
Brian P Kennedy
Keyword(s):  
Life History ◽  
Water Chemistry ◽  
Amazon Basin ◽  
Spatial Scales ◽  
Life History Strategies ◽  
Amazon River ◽  
Sr Isotope ◽  
Chemistry Data ◽  
Fish Migrations ◽  
Conservation And Management

Animal migrations provide important ecological functions and can allow for increased biodiversity through habitat and niche diversification. However, aquatic migrations in general, and those of the world's largest fish in particular, are imperiled worldwide and are often poorly understood. Several species of large Amazonian catfish carry out some of the longest freshwater fish migrations in the world, travelling from the Amazon River estuary to the Andes foothills. These species are important apex predators in the main stem rivers of the Amazon Basin and make up the regions largest fishery. They are also the only species to utilize the entire Amazon Basin to complete their life cycle. Studies indicate both that the fisheries may be declining due to overfishing, and that the proposed and completed dams in their upstream range threaten spawning migrations. Despite this, surprisingly little is known about the details of these species' migrations, or their life history. Otolith microchemistry has been an effective method for quantifying and reconstructing fish migrations worldwide across multiple spatial scales and may provide a powerful tool to understand the movements of Amazonian migratory catfish. Our objective was to describe the migratory behaviors of the three most populous and commercially important migratory catfish species, Dourada (Brachyplatystoma rousseauxii), Piramutaba (Brachyplatystoma vaillantii), and Pira?ba (Brachyplatystoma filamentosum). We collected fish from the mouth of the Amazon River and the Central Amazon and used strontium isotope signatures (87Sr/86Sr) recorded in their otoliths to determine the location of early rearing and subsequent. Fish location was determined through discriminant function classification, using water chemistry data from the literature as a training set. Where water chemistry data was unavailable, we successfully in predicted87Sr/86Sr isotope values using a regression-based approach that related the geology of the upstream watershed to the Sr isotope ratio. Our results provide the first reported otolith microchemical reconstruction of Brachyplatystoma migratory movements in the Amazon Basin. Our results indicate that juveniles exhibit diverse rearing strategies, rearing in both upstream and estuary environments. This contrasts with the prevailing understanding that juveniles rear in the estuary before migrating upstream; however it is supported by some fisheries data that has indicated the presence of alternate spawning and rearing life-histories. The presence of alternate juvenile rearing strategies may have important implications for conservation and management of the fisheries in the region.

scholarly journals Effect of Water Chemistry, Land Use Patterns, and Geographic Distances on the Spatial Distribution of Bacterioplankton Communities in an Anthropogenically Disturbed Riverine Ecosystem

2021 ◽  
Vol 12 ◽  
Author(s):  
Jun Zhao ◽  
Wang Peng ◽  
Mingjun Ding ◽  
Minghua Nie ◽  
Gaoxiang Huang
Keyword(s):  
Land Use ◽  
Environmental Factors ◽  
Water Chemistry ◽  
Geographic Distance ◽  
Land Use Patterns ◽  
Species Sorting ◽  
Mass Effects ◽  
Use Patterns ◽  
Community Variation ◽  
Bacterioplankton Communities

The spatial distribution of bacterioplankton communities in rivers is driven by multiple environmental factors, including local and regional factors. Local environmental condition is associated with effect of river water chemistry (through species sorting); ecological process in region is associated with effects of land use and geography. Here, we investigated variation in bacterioplankton communities (free-living, between 0.22 and 5 μm) in an anthropogenically disturbed river using high-throughput DNA sequencing of community 16S rRNA genes in order to investigate the importance of water chemistry, land use patterns, and geographic distance. Among environmental factors, sulfate (SO42–), manganese (Mn), and iron (Fe) concentrations were the water chemistry parameters that best explained bacterioplankton community variation. In addition, forest and freshwater areas were the land use patterns that best explained bacterioplankton community variation. Furthermore, cumulative dendritic distance was the geographic distance parameter that best explained bacterial community variation. Variation partitioning analysis revealed that water chemistry, land use patterns, and geographic distances strongly shaped bacterioplankton communities. In particular, the direct influence of land use was prominent, which alone contributed to the highest proportion of variation (26.2% in wet season communities and 36.5% in dry season communities). These results suggest that the mechanisms of species sorting and mass effects together control bacterioplankton communities, although mass effects exhibited higher contributions to community variation than species sorting. Given the importance of allochthonous bacteria input from various land use activities (i.e., mass effects), these results provide new insights into the environmental factors and determinant mechanisms that shape riverine ecosystem communities.

High spatial resolution x-ray microanalysis of interfaces

1995 ◽  
Vol 53 ◽  
pp. 284-285
Author(s):  
J. R. Michael
Keyword(s):  
Spatial Resolution ◽  
Electron Probe ◽  
Solid Angle ◽  
Collection Efficiency ◽  
Spatial Scales ◽  
Energy Dispersive Spectrometer ◽  
X Rays ◽  
X Ray ◽  
Probe Size ◽  
Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

Spatial regularities between non-immigrant and immigrant numbers in Canada

2014 ◽  
Vol 11 (1) ◽  
pp. 90-100
Author(s):  
Yigit Aydede
Keyword(s):  
Fixed Effects ◽  
Spatial Scales ◽  
National Scale ◽  
Pooled Data

The present study intends to reveal spatial regularities between non-immigrant and immigrant numbers in two different ways. First, it questions the existence of those regularities when spatial scales get finer. Second, it uses pooled data over four population censuses covering the period from 1991 to 2006, which enabled us to apply appropriate techniques to remove those unobserved fixed effects so that the estimations would accurately identify the linkage between local immigrant and non-immigrant numbers. The results provide evidence about the existence of negative spatial regularities between non-immigrant and immigrant numbers in Canada at national scale.

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