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 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.

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 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 Spatial and temporal variation of fish assemblages in a subtropical small stream of the Huangshan Mountain

2010 ◽  
Vol 56 (6) ◽  
pp. 670-677 ◽  
Author(s):  
Yunzhi Yan ◽  
Shan He ◽  
Ling Chu ◽  
Xiuying Xiang ◽  
Yanju Jia ◽  
...  
Keyword(s):  
Species Richness ◽  
Spatial Variation ◽  
Temporal Variation ◽  
Fish Assemblages ◽  
Spatial And Temporal Variation ◽  
Scaling Analysis ◽  
Small Stream ◽  
Study Sites ◽  
Species Richness And Abundance ◽  
Huangshan Mountain

Abstract Spatial and temporal variation of fish assemblages were investigated seasonally from May 2007 to February 2008 across 11 study sites in a subtropical small stream, the Puxi Stream, of the Huangshan Mountain. Along the longitudinal gradient from headwater to downstream, fish species richness and abundance increased gradually, but then decreased significantly at the lower reaches. The highest species richness and abundance were observed in August and the lowest in February. Based on analysis of similarities (ANOSIM), fish assemblages were significantly different in spatial variation but not in temporal variation. Although differences were observed both among sites and among stream orders, the lower R value in order-variation suggested stream order was not the optimal factor explaining the spatial variation of fish assemblages. In addition, dam construction did not significantly alter fish assemblages in the sites adjacent to and immediately downstream to dams. Using cluster analysis and non-metric Multi Dimensional Scaling analysis (NMS), assemblages were separated into three groups at a Bray-Curtis similarity value of 42%: the upper, middle and lower groups. Following analysis of similarity percentages of species contributions (SIMPER), shifts in occurrence or abundance of S. curriculus, Z. platypus, R. bitterling and A. fasciatus contributed most to the differences amongst the three groups. Standard Deviation Redundancy Analysis (RDA) suggested that habitat structure (such as elevation, substrate, and flow velocity) contributed to the spatial and temporal pattern of fish assemblages in the Puxi Stream. In conclusion, the fish assemblages in Puxi Stream presented significant spatial but not temporal variation. Human disturbance has perhaps induced the decrease in species diversity in the lower reaches. However, no significant change was observed for fish assemblages in sites far from and immediately downstream from low-head dams.

scholarly journals Permutation Entropy-Based Analysis of Temperature Complexity Spatial-Temporal Variation and Its Driving Factors in China

Entropy ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 1001 ◽  
Author(s):  
Zhang ◽  
Cheng ◽  
Gao
Keyword(s):  
Spatial Variation ◽  
Temporal Variation ◽  
Spatial Variations ◽  
Driving Factors ◽  
Spatial And Temporal Variation ◽  
Permutation Entropy ◽  
Temperature Changes ◽  
Temperature Trends ◽  
Regional Temperature ◽  
Main Factor

Air temperature fluctuation complexity (TFC) describes the uncertainty of temperature changes. The analysis of its spatial and temporal variation is of great significance to evaluate prediction uncertainty of the regional temperature trends and the climate change. In this study, annual-TFC from 1979–2017 and seasonal-TFC from 1983–2017 in China were calculated by permutation entropy (PE). Their temporal trend is described by the Mann-Kendall method. Driving factors of their spatial variations are explored through GeoDetector. The results show that: (1). TFC shows a downward trend generally, with obvious time variation. (2). The spatial variation of TFC is mainly manifested in the differences among the five sub-regions in China. There is low uncertainty in the short-term temperature trends in the northwest and southeast. The northeastern and southwestern regions show high uncertainties. TFC in the central region is moderate. (3). The vegetation is the main factor of spatial variation, followed by the climate and altitude, and the latitude and terrain display the lowest impact. The interactions of vegetation-altitude, vegetation-climate and altitude-latitude can interpret more than 50% of the spatial variations. These results provide insights into causes and mechanisms of the complexity of the climate system. They can help to determine the influencing process of various factors.

A review of spatial and temporal variation in grey and common seal diet in the United Kingdom and Ireland

2012 ◽  
Vol 92 (8) ◽  
pp. 1711-1722 ◽  
Author(s):  
Susie L. Brown ◽  
Stuart Bearhop ◽  
Chris Harrod ◽  
Robbie A. McDonald
Keyword(s):  
Spatial Variation ◽  
Temporal Variation ◽  
Large Scale ◽  
Fish Assemblages ◽  
Prey Availability ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Scales ◽  
The United Kingdom ◽  
The Impact ◽  
Seal Diet

Knowledge about the diet of fish-eating predators is critical when evaluating conflicts with the fishing industry. Numerous primary studies have examined the diet of grey seals Halichoerus grypus and common seals Phoca vitulina in a bid to understand the ecology of these predators. However, studies of large-scale spatial and temporal variation in seal diet are limited. Therefore this review combines the results of seal diet studies published between 1980 and 2000 to examine how seal diet varies at a range of spatial and temporal scales. Our results revealed extensive spatial variation in gadiform, perciform and flatfish consumption, likely reflecting variation in prey availability. Flatfish and gadiform consumption varied between years, reflecting changes in fish assemblages as a consequence of factors such as varying fishing pressures, climate change and natural fluctuations in populations. Perciform and gadiform consumption varied seasonally: in addition there was a significant interaction between season and seal species, indicating that grey and common seals exhibited different patterns of seasonal variation in their consumption of Perciformes and Gadiformes. Multivariate analysis of grey seal diet revealed spatial variation at a much smaller scale, with different species dominating the diet in different areas. The existence of spatial and temporal variation in seal diet emphasizes that future assessments of the impact of seal populations should not be based on past or localized estimates of diet and highlights the need for up-to-date, site specific estimates of diet composition in the context of understanding and resolving seal/fisheries conflict.

Spatial and Temporal Variation in a Population of Freshwater Mussels in shell Lake, N.W.T.

1989 ◽  
Vol 46 (8) ◽  
pp. 1392-1395 ◽  
Author(s):  
Robert C. Bailey ◽  
Roger H. Green
Keyword(s):  
Growth Rate ◽  
Population Density ◽  
Temporal Variation ◽  
Shallow Water ◽  
Age Structure ◽  
Anthropogenic Impact ◽  
Freshwater Mussels ◽  
Older Age ◽  
Spatial And Temporal Variation ◽  
Anodonta Grandis

A population of Anodonta grandis (Bivalvia; Unionidae) in a small Arctic lake was sampled in 1973 and 1986. In both of the years sampled there were about 14 times more mussels in deep (> 1.5 m) water than in shallow Water There was a decline in growth rate, a shift towards an older age structure, and a drop in population density from 2.3 to 0.65 animals per∙m−2 between 1973 and 1986. This pattern is consistent with an hypothesis of anthropogenic impact. The limitations of such an interpretation are discussed.

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