scholarly journals Spatial distribution and temporal variation of microcrustaceans assembly (Cladocera and Copepoda) in different compartments of a reservoir in the brazilian semiarid region

2018 ◽  
Vol 30 (0) ◽  
Author(s):  
Josiane Souza Santos ◽  
Nadson Ressyé Simões ◽  
Sérgio Luiz Sonoda
Keyword(s):  
Spatial Distribution ◽  
Spatial Variation ◽  
Temporal Variation ◽  
Aquatic Macrophytes ◽  
Temporal Dynamics ◽  
Lateral Compartment ◽  
Spatial And Temporal Variation ◽  
Semiarid Region ◽  
Brazilian Semiarid ◽  
Significant Spatial Variation

Abstract Aim: The objective of this study was to investigate the spatial and temporal variation of microcrustacean assemblages of a reservoir in the Brazilian semiarid region. Methods Physical and chemical water variables and samples of microcrustaceans were collected at eight sites of the reservoir between July 2013 and November 2014, in a total of seven campaigns. For this study, the reservoir was categorized in two compartments: lateral and central. Results Limnological variables showed significant temporal variation (PERMANOVA, Pseudo-F = 19.51, p = 0.001). Higher turbidity values and suspended solids were observed in the rainiest months, while during the dry months, we measured higher values of transparency, dissolved oxygen, and chlorophyll-a. It was not found significant spatial variation of limnological variables (PERMANOVA, Pseudo-F = 0.96; p = 0.394). During the study period, ten species were recorded: four Cladocera (Ceriodaphnia cornuta, Daphnia gessneri, Diaphanosoma birgei and Diaphanosoma spinulosum ) three Copepoda Calanoida (Argyrodiaptomus azevedoi, Notodiaptomus cearensis and Notodiaptomus iheringi) and three Copepoda Cyclopoida (Macrocyclops albidus, Thermocyclops minutus and Thermocyclops decipiens). The microcrustacean assemblages showed significant temporal variation (PERMANOVA, Pseudo-F = 4.34; p = 0.001) as well as significant spatial variation (PERMANOVA, Pseudo-F = 9.46; p = 0.001). The highest values of abundance and richness were observed in the lateral compartment, this result is mainly related to the presence of aquatic macrophytes in this region, because the analysis of partial RDA indicated that limnological variables explained only 11% of this variation (Pseudo-F = 2.08, p = 0.001). Conclusions The results suggest that the seasonality of the semiarid is an important factor in the temporal dynamics of the limnological variables, while the aquatic macrophytes play an important role in the spatial distribution of the microcrustacean assembly.

The Effects of Movement On Population Density Estimates of Mudflat Epifauna

1998 ◽  
Vol 78 (2) ◽  
pp. 377-385 ◽  
Author(s):  
R.S.K. Barnes
Keyword(s):  
Population Density ◽  
Spatial Variation ◽  
Temporal Variation ◽  
Spatial And Temporal Variation ◽  
Intertidal Mudflat ◽  
Density Estimates ◽  
Directional Movement ◽  
Significant Spatial Variation ◽  
Directional Component ◽  
Submerged Conditions

The soft-sediment marine benthos is well-known to be patchily distributed. To test whether this could be caused by individual epifaunal movement, spatial and temporal variation in numbers of adult mudsnails, Hydrobia ulvae, were analysed within an area of 40 m2 on an intertidal mudflat over periods of 4 or 6 d on three occasions, two of spring tides and one of neap. Significant spatial variation was always present, and significant temporal variation occurred during the spring tides. There was no variation dependent on the numbers of replicate samples taken from each station. Furthermore, movement of large, individually marked winkles, Littorina saxatilis, in the same habitat was measured and shown to be significantly directional over three series of spring tides, although the mean angle of movement varied widely between the different tidal series; storm-induced movement was particularly large. Such directional movement could account for the temporal and spatial variation seen in H. ulvae. Distances moved by winkles under permanently submerged conditions, however, did not display any directional component. Estimates of the population density and dispersion of potentially mobile or movable, intertidal epibenthos obtained on a series of individual, widely spaced days must therefore be treated with caution, however much replicated on any given occasion.

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.

Spatial variation in CO2 efflux from the soil in a mature beech forest ecosystem.

2021 ◽  
Author(s):  
Yihan Cai ◽  
Takahiro Nishimura ◽  
Hideyuki Ida ◽  
Mitsuru Hirota
Keyword(s):  
Spatial Variation ◽  
Temporal Variation ◽  
Forest Ecosystem ◽  
Linear Regression Analysis ◽  
Basal Area ◽  
Beech Forest ◽  
Controlling Factors ◽  
Spatial And Temporal Variation ◽  
Canopy Openness ◽  
Co2 Efflux

<p> Soil respiration (Rs) is the second largest carbon flux between the atmosphere and terrestrial ecosystem. Because of the large proportion, even small change in Rs would considerably impact the global carbon cycle. Therefore, it is important to accurately estimate Rs by taking its spatial and temporal variation into consideration. While the temporal variation of Rs and its controlling factors have been well-described, large unexplainable part still has been remained in the spatial variation of Rs especially in the forest ecosystems with complex structures. The objective of this study is to fill the knowledge gap about spatial variation of Rs and its controlling factors in a typical mature beech forest in Japan. Hypotheses of this study were, 1) Rs would show large spatial variation in the mature beech forest, 2) the spatial variation of Rs was mainly influenced by soil water content (SWC) and soil temperature (ST), 3) the two key factors were determined by the forest structures. This study was conducted in a 1- ha permanent study plot in the mature beech forest with significant gap-mosaic structures. To examine these hypotheses, Rs, SWC, ST and parameters related to forest structure, i.e. sum of basal area, diameter at breast height, number of trees, number of species within a radius of 5 m from the Rs measurement points, and canopy openness were measured at 121 points in different season between 2012 to 2013. In this study, all the measurements of Rs were conducted by using alkali-absorption technique.</p><p> Coefficient of variation of Rs was between 25 - 28 % which was similar to that of SWC in all the measurements. The spatial variation of Rs was relatively higher in July, August and September than that in June and October. There was no significant relationship in the spatial variation between Rs and ST in all the measurements, meanwhile, Rs was well explained by SWC in measurements conducted in August, September and October. Multiple linear regression analysis indicated that canopy openness and sum of basal area showed significant positive and negative correlation with SWC, respectively. And canopy openness explained SWC much more than sum of basal area did. This result suggested that SWC, the key factor determined the spatial variation of Rs, cannot be only explained by stems distribution and their characteristics, but also canopy architecture in the forest ecosystem.</p>

scholarly journals Aquatic macrophyte community varies in urban reservoirs with different degrees of eutrophication

2014 ◽  
Vol 26 (2) ◽  
pp. 129-142 ◽  
Author(s):  
Suelen Cristina Alves da Silva ◽  
Armando Carlos Cervi ◽  
Cleusa Bona ◽  
André Andrian Padial
Keyword(s):  
Species Richness ◽  
Temporal Variation ◽  
Indicator Species ◽  
Beta Diversity ◽  
Aquatic Macrophytes ◽  
Aquatic Macrophyte ◽  
Wiener Index ◽  
Spatial And Temporal Variation ◽  
Macrophyte Community ◽  
Aquatic Macrophyte Community

AIM: Investigate spatial and temporal variation in the aquatic macrophyte community in four urban reservoirs located in Curitiba metropolitan region, Brazil. We tested the hypothesis that aquatic macrophyte community differ among reservoirs with different degrees of eutrophication. METHODS: The reservoirs selected ranged from oligotrophic/mesotrophic to eutrophic. Sampling occurred in October 2011, January 2012 and June 2012. Twelve aquatic macrophytes stands were sampled at each reservoir. Species were identified and the relative abundance of aquatic macrophytes was estimated. Differences among reservoirs and over sampling periods were analyzed: i) through two‑way ANOVAs considering the stand extent (m) and the stand biodiversity - species richness, evenness, Shannon-Wiener index and beta diversity (species variation along the aquatic macrophyte stand); and ii) through PERMANOVA considering species composition. Indicator species that were characteristic for each reservoir were also identified. RESULTS: The aquatic macrophyte stand extent varied among reservoirs and over sampling periods. Species richness showed only temporal variation. On the other hand, evenness and Shannon-Wiener index varied only among reservoirs. The beta diversity of macrophyte stands did not vary among reservoirs or over time, meaning that species variability among aquatic macrophyte stands was independent of the stand extent and reservoir eutrophication. Community composition depended on the reservoir and sampling period. CONCLUSIONS: Our results support our initial expectation that reservoirs of different degrees of eutrophication have different aquatic macrophyte communities. As a consequence, each reservoir had particular indicator species. Therefore, monitoring and management efforts must be offered for each reservoir individually.

scholarly journals Spatial and temporal variation of precipitation characteristics in the semiarid region of Xi'an, northwest China

2021 ◽  
Author(s):  
Hao Han ◽  
Jingming Hou ◽  
Rengui Jiang ◽  
Jiahui Gong ◽  
Ganggang Bai ◽  
...  
Keyword(s):  
Temporal Variation ◽  
Arid Regions ◽  
Resource Planning ◽  
Northwest China ◽  
Annual Precipitation ◽  
Spatial And Temporal Variation ◽  
Semiarid Region ◽  
Monthly Precipitation ◽  
Xi’An City ◽  
Semi Arid

Abstract Precipitation variations mostly affect the water resource planning in semi-arid regions of northwest China. The objective of this study is to quantitatively explore the spatial and temporal variations of precipitation in different time scales in Xi'an city area. The Mann–Kendall test and wavelet analysis methods were applied to analyze the precipitation variability. In terms of temporal variation of precipitation, the results indicated that the annual precipitation exhibited a significant decreasing trend during 1951–2018. Except for summer precipitation representing a slightly increasing trend, the other seasonal precipitations had a similar decreasing trend to annual precipitation throughout 1951–2018. The monthly precipitation had different change trends, showing the precipitation from June to September could account for 58.4% of the total annual precipitation. In addition, it was clear that annual precipitation had a significant periodic change, with the periods of 6, 13, 19, and 27 years. For the spatial variation of precipitation during 1961–2018, the results showed that annual and seasonal precipitation exhibited obvious spatial differences, indicating an increasing spatial trend from north to south. Thus, understanding the precipitation variation in Xi'an city can provide a theoretical foundation of future water resources management for other cities in semi-arid regions of northwest China.

scholarly journals Spatial and temporal variation in densities of chironomid larvae (Diptera) in two lagoons and two tributaries of the upper Paraná River floodplain, Brazil

2002 ◽  
Vol 62 (4b) ◽  
pp. 807-818 ◽  
Author(s):  
J. HIGUTI ◽  
A. M. TAKEDA
Keyword(s):  
Temporal Variation ◽  
Temporal Dynamics ◽  
Paraná River ◽  
Spatial And Temporal Variation ◽  
Chironomid Larvae ◽  
River Floodplain ◽  
Parana River ◽  
Upper Paraná River Floodplain ◽  
Upper Paraná River ◽  
Paraná River Floodplain

Chironomid larvae were collected and abiotic variables measured at monthly intervals at 21 sampling stations in two lagoons (Guaraná and Patos) and two tributaries (Baía and Ivinheima) of the Upper Paraná River floodplain. The genera Procladius, Chironomus, Goeldichironomus, and Polypedilum were dominant in the lagoons and in the Baía River, while Cryptochironomus and Lopescladius were more dominant in the Ivinheima River. The similarity in the generic composition of the chironomids of the lagoons and the Baía River is probably due to the fact that this river presents hydrodynamic characteristics similar to those of the lagoons. The results obtained suggest that the hydrodynamics of these environments are the main factor determining spatial variation in the chironomid fauna. This is intuitively clear, as this factor itself determines sediment type, quantity of organic matter and presence or absence of aquatic macrophytes. However, on a seasonal scale, the flood pulse seems to be the main controlling factor of the temporal variation in densities and dominance of chironomid larvae. Given that this factor has a large influence on the temporal dynamics of several limnological variables, this is again a logical correlation. Our results suggest a strong relationship between the variations in the chironomid community and fluctuations in limnological characteristics.

scholarly journals Temporal and spatial variation of limnological variables and biomass of different macrophyte species in a Neotropical reservoir (São Paulo - Brazil)

2013 ◽  
Vol 25 (4) ◽  
pp. 387-397 ◽  
Author(s):  
Flávia Bottino ◽  
Maria do Carmo Calijuri ◽  
Kevin Joseph Murphy
Keyword(s):  
Spatial Variation ◽  
Temporal Variation ◽  
Environmental Variables ◽  
Plant Distribution ◽  
Pistia Stratiotes ◽  
Spatial And Temporal Variation ◽  
Trophic State Index ◽  
Water And Sediment ◽  
Inorganic Substances ◽  
Eichhornia Azurea

AIM: This study reports an investigation of limnological characteristics and aquatic macrophyte occurrence in a neotropical reservoir in order to assess the spatio-temporal variation of water and sediment variables and their influence on plant distribution. METHODS: Macrophytes, water and sediment samples were collected from a Brazilian reservoir in different seasons from four main arms of the reservoir. In total sixteen water-sediment variables were analyzed including N:P ratio and Trophic State Index. The plants were collected using a quadrat sampling procedure and the dry weight per sample was measured. MANOVA was performed to evaluate spatial and temporal variation of environmental variables as well as seasonal biomass differences. To assess the relationship among environmental variables and macrophytes an ordination analysis (using Canonical Correspondence Analysis: CCA) was carried out. RESULTS: The spatial and temporal variation of limnological variables generated a heterogeneous system which supports the presence of different species of macrophyte. pH, dissolved oxygen and sediment composition were important predictors of Polygonum lapathifolium occurrence while nutrients were associated with Eichhornia crassipes and Pistia stratiotes. Inorganic substances were related to biomass variation of Eichhornia azurea and Myriophyllum aquaticum. CONCLUSIONS: The spatial variation of the environmental variables has caused heterogeneity in the reservoir and it may support the occurrence of different species of macrophyte. Limnological variables highlighted in CCA are important to predict the species occurrence and their control in the study area.

scholarly journals Hot spot detection and spatio-temporal dynamics of dengue in Queensland, Australia

2014 ◽  
Vol XL-8 ◽  
pp. 197-204 ◽  
Author(s):  
S. Naish ◽  
S. Tong
Keyword(s):  
Temporal Variation ◽  
Temporal Dynamics ◽  
Hot Spot ◽  
Seasonal Pattern ◽  
Temporal Distribution ◽  
Health Concern ◽  
Spatial And Temporal Variation ◽  
Dengue Case ◽  
Spatio Temporal ◽  
Over Time

Dengue has been a major public health concern in Australia since it re-emerged in Queensland in 1992–1993. This study explored spatio-temporal distribution and clustering of locally-acquired dengue cases in Queensland State, Australia and identified target areas for effective interventions. A computerised locally-acquired dengue case dataset was collected from Queensland Health for Queensland from 1993 to 2012. Descriptive spatial and temporal analyses were conducted using geographic information system tools and geostatistical techniques. Dengue hot spots were detected using SatScan method. Descriptive spatial analysis showed that a total of 2,398 locally-acquired dengue cases were recorded in central and northern regions of tropical Queensland. A seasonal pattern was observed with most of the cases occurring in autumn. Spatial and temporal variation of dengue cases was observed in the geographic areas affected by dengue over time. Tropical areas are potential high-risk areas for mosquito-borne diseases such as dengue. This study demonstrated that the locally-acquired dengue cases have exhibited a spatial and temporal variation over the past twenty years in tropical Queensland, Australia. There is a clear evidence for the existence of statistically significant clusters of dengue and these clusters varied over time. These findings enabled us to detect and target dengue clusters suggesting that the use of geospatial information can assist the health authority in planning dengue control activities and it would allow for better design and implementation of dengue management programs.

scholarly journals The influence of hydrodynamics on the spatial and temporal variation of phytoplankton pigments in a large, sub-tropical coastal lake (Brazil)

2004 ◽  
Vol 47 (4) ◽  
pp. 587-600 ◽  
Author(s):  
Luciana de Souza Cardoso ◽  
David da Motta Marques
Keyword(s):  
Spatial Distribution ◽  
Temporal Variation ◽  
Diurnal Cycle ◽  
Shallow Lake ◽  
Temporal Distribution ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Distribution ◽  
Coastal Lake ◽  
Phytoplankton Pigments ◽  
Horizontal Heterogeneity

This study evaluated the spatial and temporal distribution of phytoplankton pigments in Itapeva Lake and its relationship with hydrodynamic aspects. Regarding spatial distribution, a decreasing N®S gradient was generally observed for the pigments, except in summer. This inversion observed during the summer was influenced by the predominant fetch (N-E). The horizontal heterogeneity was proved (ANOVA) for all seasons of the year, except spring. Spatially in spring, the vertical variance was much more significant (p<0.05) than the horizontal one. The sampling shifts presented a permanent degree of variability among the seasons of the year, showing the existence of a diurnal cycle in the concentration of chlorophyll a. This behavior was related to the fetch, mainly from the NE and SW quadrants, disturbing the system because it is a shallow lake. This confirmed the influence of the Itapeva Lake's hydrodynamic regime on the spatial-temporal distribution of the phytoplankton pigments.

scholarly journals The effects of spatial and temporal replicate sampling on eDNA metabarcoding

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7335 ◽  
Author(s):  
Kevin K. Beentjes ◽  
Arjen G. C. L. Speksnijder ◽  
Menno Schilthuizen ◽  
Marten Hoogeveen ◽  
Berry B. van der Hoorn
Keyword(s):  
Spatial Distribution ◽  
Temporal Variation ◽  
Operational Taxonomic Unit ◽  
Taxonomic Diversity ◽  
Time Frame ◽  
Temporal Variations ◽  
Spatial And Temporal Variation ◽  
Small Scale ◽  
Time Intervals ◽  
Population Turnover

Background The heterogeneous nature of environmental DNA (eDNA) and its effects on species detection and community composition estimates has been highlighted in several studies in the past decades. Mostly in the context of spatial distribution over large areas, in fewer occasions looking at spatial distribution within a single body of water. Temporal variation of eDNA, similarly, has mostly been studied as seasonality, observing changes over large periods of time, and often only for small groups of organisms such as fish and amphibians. Methods We analyzed and compared small-scale spatial and temporal variation by sampling eDNA from two small, isolated dune lakes for 20 consecutive weeks. Metabarcoding was performed on the samples using generic COI primers. Molecular operational taxonomic unit (MOTUs) were used to assess dissimilarities between spatial and temporal replicates. Results Our results show large differences between samples taken within one lake at one point in time, but also expose the large differences between temporal replicates, even those taken only 1 week apart. Furthermore, between-site dissimilarities showed a linear correlation with time frame, indicating that between-site differences will be inflated when samples are taken over a period of time. We also assessed the effects of PCR replicates and processing strategies on general patterns of dissimilarity between samples. While more inclusive PCR replicate strategies lead to higher richness estimations, dissimilarity patterns between samples did not significantly change. Conclusions We conclude that the dissimilarity of temporal replicates at a 1 week interval is comparable to that of spatial replicate samples. It increases, however, for larger time intervals, which suggests that population turnover effects can be stronger than community heterogeneity. Spatial replicates alone may not be enough for optimal recovery of taxonomic diversity, and cross-comparisons of different locations are susceptible to inflated dissimilarities when performed over larger time intervals. Many of the observed MOTUs could be classified as either phyto- or zooplankton, two groups that have gained traction in recent years as potential novel bio-indicator species. Our results, however, indicate that these groups might be susceptible to large community shifts in relatively short periods of time, highlighting the need to take temporal variations into consideration when assessing their usability as water quality indicators.

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