scholarly journals Similar small-scale variation of diatom assemblages on different substrates in a mesotrophic stream

2015 ◽  
Vol 74 (2) ◽  
pp. 363-376 ◽  
Author(s):  
Maria Kahlert ◽  
Ivana Savatijević Rašić
Keyword(s):  
Environmental Factors ◽  
Species Composition ◽  
Spatial Variation ◽  
Anthropogenic Impacts ◽  
Sampling Site ◽  
Small Distance ◽  
Benthic Diatom ◽  
Small Scale ◽  
Diatom Species ◽  
Diatom Assemblages

Abstract The aim of the present study was to analyze if small-scale spatial variation of benthic diatom assemblages has consequences for biomonitoring. Benthic diatom samples were collected at one sampling site in a mesotrophic stream in Middle-Sweden from stone and plant (macrophytes and mosses) substrate. Our results showed that spatial variation of both the diatom species composition and the calculated bioindices were similar on both small (distance of centimeter) and medium (distance of decimeters) scales. Spatial variation was also similar on both studied substrates. This implies that it does not matter if a small or a larger area is sampled for biomonitoring as long as no major environmental factors impact certain sites systematically. Diatom assemblages and indices were significantly different between substrates. Spatial variation did not contribute much to this variation, and variation on a slide was unimportant. These results confirm earlier findings that smallscale spatial variation is not a problem when using diatoms to detect anthropogenic impacts to a stream or lake.

Variability in organic matter lost by combustion in a boreal bog during the 2001 Chisholm fire

2003 ◽  
Vol 33 (12) ◽  
pp. 2509-2513 ◽  
Author(s):  
Brian W Benscoter ◽  
R Kelman Wieder
Keyword(s):  
Organic Matter ◽  
Species Composition ◽  
Spatial Variability ◽  
Spatial Variation ◽  
Fire Severity ◽  
Small Scale ◽  
Western Canada ◽  
Direct Combustion ◽  
Site Variation

Fire directly releases carbon (C) to the atmosphere through combustion of biomass. An estimated 1470 ± 59 km2 of peatland burns annually in boreal, western Canada, releasing 4.7 ± 0.6 Tg C to the atmosphere via direct combustion. We quantified within-site variation in organic matter lost via combustion in a bog peatland in association with the 116 000-ha Chisholm, Alberta, fire in 2001. We hypothesized that for peatlands with considerable small-scale microtopography (bogs and treed fens), hummocks will burn less than hollows. We found that hollows exhibit more combustion than hummocks, releasing nearly twice as much C to the atmosphere. Our results suggest that spatial variability in species composition and site hydrology within a landform and across a landscape could contribute to considerable spatial variation in the amounts of C released via combustion during peatland fire, although the magnitude of this variation may be dependent on fire severity.

scholarly journals Life-history of the South American darter, Characidium pterostictum (Crenuchidae): evidence for small scale spatial variation in a piedmont stream

2008 ◽  
Vol 6 (4) ◽  
pp. 591-598 ◽  
Author(s):  
Fernando Gertum Becker ◽  
Silene de Carvalho ◽  
Sandra Maria Hartz
Keyword(s):  
Life History ◽  
Spatial Variation ◽  
Life History Theory ◽  
Spatial Scales ◽  
Gonadosomatic Index ◽  
Sampling Site ◽  
Small Scale ◽  
Upstream Site ◽  
Trade Off ◽  
Disturbed Site

The present study compares the reproduction, condition and size of the small characiform fish, Characidium pterostictum, sampled at close sites differing in severity of flash flood effects. Data were obtained from seasonal samples in two sites situated 8 km apart in the same stream. In the upstream site, habitat is more severely affected by flash floods than in the downstream site, and this difference was hypothesized to produce differences in life history and individual reproduction trade-off patterns, as predicted by life-history theory. The results provided evidence for small-scale spatial variation in life-history and trade-off patterns within the studied population. At the most severely disturbed site, C. pterostictum displayed a trade-off pattern that favored reproductive life-span (e.g., larger size, higher and seasonally stable condition, larger mean size of mature females) over instantaneous reproductive output (lower gonadosomatic index), while the opposite pattern was observed in the less disturbed site. Because of the differences in disturbance effects between each sampling site, these results suggest that within-stream variability in the severity of hydrological disturbance can influence life-history patterns at small spatial scales. An implication of the results is that fish occupying areas that are hydrologically more variable within a stream are not necessarily at an energetic or reproductive disadvantage, but may be simply under environmental conditions that favor distinct patterns of energy allocation (or trade-offs) and population persistence, as predicted by life-history theory. Therefore, plasticity in life-history is expected to be common in stream fish populations that are widespread in a stream system with spatially variable or patchy habitat characteristics.

scholarly journals Diatom species composition of the Nisava river and its tributaries Jerma and Temska rivers (southern Serbia)

2012 ◽  
Vol 64 (3) ◽  
pp. 1127-1140 ◽  
Author(s):  
Jelena Andrejic ◽  
Jelena Krizmanic ◽  
M. Cvijan
Keyword(s):  
Species Composition ◽  
Benthic Diatom ◽  
Future Research ◽  
Diatom Species ◽  
Diatom Flora ◽  
Chemical Agents ◽  
Floristic Analysis

The main objective of this paper is to report the diatom taxa identified from the Nisava River and its tributaries, the Jerma and Temska rivers. The study area included 11 sampling sites along the Nisava River, with one site on the Jerma River and one on the Temska River. Monthly samples (from stones, sediments and macrophytes) were collected from May 2008 to May 2009. Diatom frustules were cleaned with chemical agents, and mounted on permanent slides. In total, 194 diatom taxa were identified. The most species rich genera are Navicula (25), Nitzschia (17) and Gomphonema (13), while other genera are presented with one or more species. Detailed floristic analysis of the benthic diatom flora has not been conducted before on these rivers. Therefore, this paper provides a baseline for future research.

scholarly journals Diatom species composition and their seasonal dynamics in the Timok River basin

2021 ◽  
pp. 4-4
Author(s):  
Nikola Đukić ◽  
Tatjana Jakšić ◽  
Olivera Papović ◽  
Predrag Vasić
Keyword(s):  
Hydrogen Peroxide ◽  
Quantitative Analysis ◽  
Species Composition ◽  
River Basin ◽  
Seasonal Dynamics ◽  
Organic Material ◽  
Ecological Study ◽  
Research Work ◽  
Benthic Diatom ◽  
Diatom Species

The aim of this paper was to present the composition and seasonal dynamics of epilthic diatoms in the Timok River basin. The diatom samples were collected along the Timok River basin in March, May, August and November 2017. Permanent diatom slides were prepared after oxidizing the organic material by the hydrogen peroxide (H 2 O 2). The cleaned diatom materials were mounted on permanent slides using ZRAX glue. A total of 85 taxa were identified in the Timok River Basin. The benthic diatom taxa belong to 31 gene ra with the highest diversity observed within Navicula Bory (15), Nitzschia Hassall (12) and Gomphonema Ehrenberg (8). Quantitative analysis showed that in all seasons, Achnanthidium minutissimum and Amphora pediculus were dominant taxa. In May, they were joined by the Achnanthidium pyrenaicum, Gomphonema olivaceum and Ulnaria ulna; in August by the Cocconeis placentula, Denticula kuetzingii, Melosira varians, Navicula metareichardtiana, Nitzschia capitellata, N. fonticola and N. palea; in November by the D. kuetzingii, G. olivaceum, G. pumilum, N. metareichardtiana, N. veneta, Nitzschia capitellata and N. palea and in March by A. pyrenaicum, Diatoma moniliformis, G. olivaceum, N. palea and U. ulna. Our research is the floristical and ecological study of benthic diatoms in this basin and can form the groundwork for further research work.

scholarly journals Diatom species composition in the Raska river (Southwestern Serbia)

2015 ◽  
pp. 29-40
Author(s):  
Danijela Vidakovic ◽  
Jelena Krizmanic ◽  
Sanja Sovran ◽  
Katarina Stojanovic ◽  
Jelena Djordjevic
Keyword(s):  
Species Composition ◽  
Benthic Diatom ◽  
Diatom Species ◽  
Diatom Flora ◽  
Epilithic Diatoms ◽  
Acid Method ◽  
Floristic Analysis

The paper presents data on the composition of epilithic diatoms in the Raska River. Samples were collected by scraping stone surfaces with a brush from 5 localities along the Raska River in April, June, August and November 2011 and March and May 2012. Diatom frustules were cleaned using cold acid method, and mounted on permanent slides. An investigation of the Raska River resulted in description of 106 diatom taxa. The most species rich genera are Navicula (10), Gomphonema (10) and Nitzschia (9), while other genera are presented with one or more species. Detailed floristic analysis of the benthic diatom flora in this river has not been conducted before. Therefore, this paper provides a groundwork for future researches.

Influences of forest structure and landscape features on spatial variation in species composition in a palm community in central Amazonia

2014 ◽  
Vol 30 (6) ◽  
pp. 565-578 ◽  
Author(s):  
Lilian Figueiredo Rodrigues ◽  
Renato Cintra ◽  
Carolina Volkmer Castilho ◽  
Ocírio de Sousa Pereira ◽  
Tânia P. Pimentel
Keyword(s):  
Species Composition ◽  
Spatial Variation ◽  
Forest Structure ◽  
Full Range ◽  
Small Scale ◽  
Tropical Rain Forests ◽  
Ecological Gradients ◽  
Landscape Features ◽  
Palm Species ◽  
Central Amazonia

Abstract:The mechanisms that maintain palm species diversity in tropical rain forests are still debated. Spatial variation in forest structure produces small-scale environmental heterogeneity, which in turn can affect plant survival and reproductive performance. An understanding of how palms respond to variation in forest heterogeneity may help to explain the diversity and structure of their assemblages. We used multivariate ordination statistics and multiple linear models to analyse how palm assemblages are affected by forest structure and landscape features in central Amazonia. In 72 (250×4 m) forest plots distributed over an area of 64 km2, we recorded all seedling and adult palms, and measured topographic and soil variables, and components of forest structure and tree abundance. We found 16976 adults and 18935 seedlings of 46 palm species and five varieties including two morphological forms making a total of 50 botanical entities. Results show that landscape features (altitude, slope, proportions of soil sand and clay) and various components of forest structure (such as degree of forest openness, abundance of forest trees, logs and snags, and leaf litter mass), influence spatial variation in richness, abundance and species composition of palms, creating ecological gradients in palm community composition. Despite the statistically significant effects of environmental variables, most species occurred throughout the full range of the ecological gradients we studied, indicating that there is either relatively weak niche specialization in the palms, or that the competition between the species is mediated by diffuse demographic processes that cannot be evaluated only through studies of species distributions.

Diatomological aspects of the Fenn’s and Whixall Mosses complex (Shropshire, UK)

2014 ◽  
Vol 43 (3) ◽  
Author(s):  
Katarzyna Szulc ◽  
Lynn Besenyei ◽  
Bogusław Szulc ◽  
Barbara Rakowska
Keyword(s):  
Nature Reserve ◽  
Low Ph ◽  
Benthic Diatom ◽  
Peat Bogs ◽  
Diatom Species ◽  
Diatom Assemblages ◽  
Data Set ◽  
Special Scientific ◽  
Ecosystem Level ◽  
A Site

AbstractPeat bogs are unique and important habitats for biodiversity at the species and ecosystem level where low pH of water plays a major role. The main objective of the present study was to compare the benthic diatom assemblage structure of the selected part of the Fenn’s and Whixall Mosses complex in order to verify whether selected sampling sites differ from each other. The complex is a cut-over, lowland raised mire, which is a National Nature Reserve (NNR) and a Site of Special Scientific Interest (SSSI).Altogether 92 diatom species were identified in 72 benthic samples collected between September 2008 and August 2009 from six selected sampling sites. Statistical cluster analysis was used to classify diatom samples and to observe the structure of diatom assemblages. The results of this analysis grouped the data set into 3 clusters with 24 samples from each of the two sampling sites in one cluster. Such a clear division shows that pH of water has an impact on the species composition, the richness and diversity of benthic diatom assemblages.

Non-wadeable river bioassessment: spatial variation of benthic diatom assemblages in Pacific Northwest rivers, USA

Hydrobiologia ◽  
2012 ◽  
Vol 684 (1) ◽  
pp. 241-260 ◽  
Author(s):  
Yangdong Pan ◽  
Robert M. Hughes ◽  
Alan T. Herlihy ◽  
Philip R. Kaufmann
Keyword(s):  
Spatial Variation ◽  
Pacific Northwest ◽  
Benthic Diatom ◽  
Diatom Assemblages

scholarly journals Predicting the Presence of Leptospires in Rodents from Environmental Indicators Opens Up Opportunities for Environmental Monitoring of Human Leptospirosis

2021 ◽  
Vol 13 (2) ◽  
pp. 325
Author(s):  
Leon Biscornet ◽  
Christophe Révillion ◽  
Sylvaine Jégo ◽  
Erwan Lagadec ◽  
Yann Gomard ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Environmental Factors ◽  
Control Strategies ◽  
Sampling Site ◽  
Rattus Rattus ◽  
Environmental Parameters ◽  
Environmental Indicators ◽  
Small Island ◽  
Urban Landscapes ◽  
Infection Prevalence

Leptospirosis, an environmental infectious disease of bacterial origin, is the infectious disease with the highest associated mortality in Seychelles. In small island territories, the occurrence of the disease is spatially heterogeneous and a better understanding of the environmental factors that contribute to the presence of the bacteria would help implement targeted control. The present study aimed at identifying the main environmental parameters correlated with animal reservoirs distribution and Leptospira infection in order to delineate habitats with highest prevalence. We used a previously published dataset produced from a large collection of rodents trapped during the dry and wet seasons in most habitats of Mahé, the main island of Seychelles. A land use/land cover analysis was realized in order to describe the various environments using SPOT-5 images by remote sensing (object-based image analysis). At each sampling site, landscape indices were calculated and combined with other geographical parameters together with rainfall records to be used in a multivariate statistical analysis. Several environmental factors were found to be associated with the carriage of leptospires in Rattus rattus and Rattus norvegicus, namely low elevations, fragmented landscapes, the proximity of urbanized areas, an increased distance from forests and, above all, increased precipitation in the three months preceding trapping. The analysis indicated that Leptospira renal carriage could be predicted using the species identification and a description of landscape fragmentation and rainfall, with infection prevalence being positively correlated with these two environmental variables. This model may help decision makers in implementing policies affecting urban landscapes and/or in balancing conservation efforts when designing pest control strategies that should also aim at reducing human contact with Leptospira-laden rats while limiting their impact on the autochthonous fauna.

scholarly journals Surface Sediment Diatom Assemblages Response to Water Environment in Dongping Lake, North China

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 339
Author(s):  
Shuangshuang Liu ◽  
Min Yao ◽  
Shiyue Chen ◽  
Xingzhong Yuan
Keyword(s):  
Environmental Factors ◽  
Water Environment ◽  
Oxygen Demand ◽  
Diatom Assemblages ◽  
Multivariate Statistical ◽  
Dongping Lake ◽  
Autumn And Winter ◽  
Response To Water ◽  
The Relationship ◽  
Significant Factors

The relationship between the diatom taxa preserved in surface lake sediments and environmental variables in Dongping Lake was explored using multivariate statistical methods. The statistical analysis showed that the lake was eutrophicated in all seasons. Transparency, chlorophyll a (Chla) and total phosphorus (TP) were the dominant environmental factors in spring and summer, and NH4+-N and chemical oxygen demand (COD) were the dominant environmental factors in autumn and winter. Sixteen genera and 43 species of diatom were found in the surface sediments, and the dominant diatom genera were Aulacoseira, Ulnaria, Cyclotella, Navicula and Fragilaria. A redundancy analysis (RDA) and Monte Carlo permutation 20 test revealed that COD, pH, TP, conductivity and transparency were significant factors influencing diatom assemblage change, meaning that the distribution of the diatom assemblages were mostly influenced by nutrient composition, light intensity and ion concentrations.

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