scholarly journals Ecological conditions of the Waterchestnut (Trapa natans L.) in the Danube Delta (Romania)

2021 ◽  
Vol 23 (3) ◽  
pp. 1-16
Author(s):  
Erika Schneider-Binder
Keyword(s):  
Cross Section ◽  
Water Body ◽  
Research Data ◽  
Water Dynamics ◽  
Ecological Niches ◽  
Running Waters ◽  
Danube Delta ◽  
Water Level Changes ◽  
Trapa Natans ◽  
Standing Waters

Abstract The diversity of water body types in the Danube Delta offers appropriate ecological niches for the colonisation of frequently large stands of the waterchestnut (Trapa natans). Their phytocoenoses were observed in slowly running and standing waters from clear, sediment-poor, to turbid and sediment-rich waters on muddy ground. Trapa natans occurs in standing, and slowly running, waters and is well adapted to fluctuation of water level changes. The water dynamics is responsible for the composition of accompanying species of the phytocoenoses. The particular zonation, demonstrated by a cross section shows the adaption to the structure and the water flow of certain water bodies. Comparing older and newer research data, a decline of the populations of waterchestnuts became visible.

scholarly journals Results of 10 years sampling of Chironomidae from German lowland running waters differing in degradation

2018 ◽  
Author(s):  
Claus Orendt
Keyword(s):  
Water Body ◽  
Statistical Significance ◽  
Detrended Correspondence Analysis ◽  
Careful Examination ◽  
Running Waters ◽  
Assessment Practice ◽  
Body Type ◽  
Running Water ◽  
North East ◽  
Species Preferences

Based on data from monitoring in north-east Germany (Land Brandenburg) over a decade, chironomid taxa and their abundances were analysed for their preferences for certain running water types and degradation levels. A detrended correspondence analysis (DCA) revealed that the distribution of the taxa was determined by both, degradation level and water body type. A series of taxa was positively or negatively correlated to degradation, however, frequently only in certain water body types. In other types, they played no major role or were evenly distributed along the degradation gradient. Higher correlations were found for taxa favouring ‘good’ and 'poor' or 'bad' conditions than for preferers of ‘moderate’ status. The results allow to validate indices and weigths of indicators derived from high frequencies of the taxa in certain one or more quality class(es). The preferred ocurrencies elaborated have to be discussed or tested for plausiblity before using or evaluating powerful indicator taxa for classifications or revisions in assessment practice. A reduction of the taxonomical precision to genus level lowered the statistical significance and requires careful examination of the species preferences of the genus.

Re-established after hundred years: Definition of Hygrobates prosiliens Koenike, 1915, based on molecular and morphological evidence, and redescription of H. longipalpis (Hermann, 1804) (Acariformes, Hydrachnidia, Hygrobatidae)

2019 ◽  
Vol 24 (8) ◽  
pp. 1490-1511 ◽  
Author(s):  
Vladimir Pešić ◽  
Lukasz Broda ◽  
Miroslawa Dabert ◽  
Reinhard Gerecke ◽  
Peter Martin ◽  
...  
Keyword(s):  
Original Description ◽  
Point Of View ◽  
Morphological Evidence ◽  
Running Waters ◽  
Dna Barcodes ◽  
Morphological Examination ◽  
Western Palaearctic ◽  
Definition Of ◽  
Standing Waters ◽  
European Populations

DNA-barcodes reveal that European populations attributed to Hygrobates longipalpis (Hermann, 1804), thus far considered a common inhabitant of standing and slowly flowing running waters all over the Western Palaearctic, represent two distinct lineages, both widely distributed over the continent. They are differentiated also from an ecological point of view, with specimens from standing waters ("clade I") separated from specimens collected in slowly running waters ("clade II"). Morphological examination revealed that, based on the length ratio of proximo- and distomedial setae on terminal segments of fourth legs, two morphospecies correspond to these two clades. As molecular examination of a specimen from the type locality of H. prosiliens Koenike, 1915 (Bremen, Heiligenrode) shows that it belongs to "clade I", populations from standing waters are attributed to that species. In view of the sketchy original description, loss of holotype and insufficient locality data of H. longipalpis, we arbitrarily assign to it stream-dwelling populations of "clade II" and designate a neotype.

scholarly journals China’s inland water dynamics: The significance of water body types

2020 ◽  
Vol 117 (25) ◽  
pp. 13876-13878 ◽  
Author(s):  
Jingying Zhu ◽  
Chunqiao Song ◽  
Jida Wang ◽  
Linghong Ke
Keyword(s):  
Water Body ◽  
Water Dynamics ◽  
Inland Water

Caddis-flies (Insecta: Trichoptera) from the Insect Limestone (Bembridge Marls, Late Eocene) of the Isle of Wight, UK

2013 ◽  
Vol 104 (3-4) ◽  
pp. 327-333 ◽  
Author(s):  
Irina D. Sukatsheva
Keyword(s):  
Water Body ◽  
Single Species ◽  
Late Eocene ◽  
Running Waters ◽  
Isle Of Wight ◽  
Caddis Flies

ABSTRACTThe trichopteran assemblage of the Late Eocene Bembridge Marls is revised. six species in five genera and four families are identified, with four species and two genera described as new: (Beraeidae: Beraeodes vectensis Cockerell, 1921 and B. anglicus Cockerell, 1921; Phryganeidae: Bembridgea insularia gen. sp. nov.; Polycentropodidae: ?Plectrocnemia incompleta Sukatsheva, sp. nov.; Philopotamidae: Wormaldia longaeva Sukatsheva, sp. nov.; incertae familiae: Paleodicella anomala Sukatsheva, gen. sp. nov.). The assemblage is unique in being absolutely dominated by the generally uncommon family Beraeidae, and particularly by the single species Beraeodes vectensis. Except for a representative of ubiquitous Phryganaeidae, all the caddis-flies recorded apparently had oxy- and psychrophilous larvae confined to springs and cold streams (or else mosses near water), thus indicating the absence of fresh lakes or slow running waters near the depositional water body.

scholarly journals Impact of a Thermocline on Water Dynamics in Reservoirs – Dobczyce Reservoir Case

2017 ◽  
Vol 64 (2) ◽  
pp. 189-203
Author(s):  
Paweł S. Hachaj ◽  
Monika Szlapa
Keyword(s):  
Water Body ◽  
Stratified Flow ◽  
Bottom Layer ◽  
Water Dynamics ◽  
Dam Reservoirs ◽  
Flow Approximation ◽  
Shallow Reservoirs ◽  
Whole Water

Abstract While modeling water dynamics in dam reservoirs, it is usually assumed that the flow involves the whole water body. It is true for shallow reservoirs (up to several meters of depth) but may be false for deeper ones. The possible presence of a thermocline creates an inactive bottom layer that does not move, causing all the discharge to be carried by the upper strata. This study compares the results of hydrodydynamic simulations performed for the whole reservoir to the ones carried out for the upper strata only. The validity of a non-stratified flow approximation is then discussed.

Inland waters in the Inner Hebrides

1983 ◽  
Vol 83 ◽  
pp. 229-244
Author(s):  
P. S. Maitland ◽  
A. V. Holden
Keyword(s):  
Great Britain ◽  
Plant Communities ◽  
Small Proportion ◽  
Aquatic Plant ◽  
Inland Waters ◽  
Running Waters ◽  
Land Area ◽  
Outer Hebrides ◽  
Standing Waters ◽  
Total Resource

SynopsisThe Inner Hebrides make up only a small proportion of the land area but a relatively higher percentage of the area of standing waters of Great Britain. Analyses of the 1:63,360 maps have provided the total numbers of standing and running waters on the islands (1,542 and 1,615 respectively) and are the basis for estimating the total resource there. The majority of lochs are small and relatively low lying. Most of the streams too are small and rarely larger than 4th order. Chemically, the waters are variable and range from some very acid nutrient-poor lochs on Islay to the unique marl lochs of Lismore. The algae of these islands have only occasionally been sampled and relatively little is known either about the higher aquatic plant communities—the ones studied are similar to those on the mainland. Few studies of the invertebrates of the inland waters have been carried out, and none of the surveys has been comprehensive. A review of the published and new data has enabled a broad account of the invertebrate communities to be presented. Only 15 species of fish occur here and most of the waters are dominated by the indigenous salmonids (salmon, trout and charr), sticklebacks or eels. Comparisons of the inland waters of the Inner Hebrides with those of other island groups (the Outer Hebrides and Shetlands) and the mainland of Scotland (especially Tayside) show that they have greater afiinities with the latter.

scholarly journals The Demographic Success of Marsilea Quadrifolia L. in a Man-Made Water Body from Danube Delta Biosphere Reservation

2015 ◽  
Vol 17 (1) ◽  
pp. 121-132
Author(s):  
Daniela Strat
Keyword(s):  
Water Body ◽  
Biosphere Reserve ◽  
Danube Delta ◽  
Demographic Trend ◽  
Aquatic Fern ◽  
Marsilea Quadrifolia ◽  
Unique Species ◽  
Danube Delta Biosphere Reserve ◽  
Demographic Evolution

Abstract Marsilea quadrifolia L. (water clover) is a unique species from Romanian flora that belongs to the Marsileaceae family and is one of the most vulnerable plants in Europe due to the loss of its habitats. In this paper, the demographic evolution of a new M. quadrifolia population in the Danube Delta Biosphere Reserve and its natural and anthropic threats are reported. The aquatic fern, M. quadrifolia, has colonized a suitable man-made water body. After a decade of monitoring, the demographic trend is positive but the support capacity of habitat for the water clover remains limited in the long term. The population is vulnerable due to succession of vegetation and its vicinity with a human settlement. The establishment of a micro-reserve represents a suitable method to protect and maintain this threatened M. quadrifolia population.

scholarly journals STRESS-STRAIN STATE OF REINFORCED CONCRETE BEAMS STRENGTHENED WITH A NEW EXTERNAL STEEL STRUCTURE

2017 ◽  
Vol 1 (48) ◽  
pp. 90-99
Author(s):  
V. P. Zhyrakhivskyi ◽  
М. G. Chekanovych ◽  
О. М. Chekanovych
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Rectangular Cross Section ◽  
Bending Moment ◽  
Steel Structure ◽  
Research Data ◽  
Reinforced Concrete Beams ◽  
Reinforced Beams ◽  
Steel Bars

The study presents a new structure for strengthening of one-span reinforced concrete beams in rectangular cross-section using external steel bars. The specific feature of the proposed strengthening is the unloading of the compressed upper zone of a beam with simultaneous compression of its lower stretched zone. The article considers some variants of making the strengthening structure with rigid and flexible reinforcement elements for faster tension of external bars, and the variant including only flexible elements. It provides a design scheme and method for such reinforced beams. The study provides experimental research data on the series of beams with different parameters of the strengthening structure in the form of «bending moment – deflection» and «bending moment - deformation of concrete» dependencies.

scholarly journals Aquatic Macrophyte Communities of the Gorgova-Isac-Uzlina Area (Danube Delta, Romania)

2018 ◽  
Vol 20 (3) ◽  
pp. 39-56
Author(s):  
Erika Schneider-Binder
Keyword(s):  
Water Quality ◽  
Water Body ◽  
Aquatic Macrophytes ◽  
Aquatic Macrophyte ◽  
Physical Parameters ◽  
Danube Delta ◽  
Human Intervention ◽  
Ecological Network ◽  
Ecological Requirements ◽  
Neighboring Area

Abstract With its diversity of water body types, the Danube Delta offers large possibilities for studies of aquatic macrophytes, their ecological requirements, ecological amplitude and communities. Sensitive to changes in water quality and physical parameters due to human intervention in the natural ecological network, aquatic macrophytes are used as quality indicators. Using the example of the system of channels and lakes of the Gorgova-Isac-Uzlina complex and some examples from the neighboring area, the aquatic macrophytes and their communities are presented and discussed in relation to the characteristics of the habitats and the changes of the environment in the course of decades, since human intervention in the delta.

About the improving the technique of timber products quality assessment

2017 ◽  
Vol 6 (4) ◽  
pp. 173-178
Author(s):  
Задраускайте ◽  
Natalya Zadrauskayte ◽  
Гузенко ◽  
Natal'ya Guzenko
Keyword(s):  
Data Processing ◽  
Quality Assessment ◽  
Cross Section ◽  
Rank Correlation ◽  
Correlation Coefficients ◽  
Current Approach ◽  
Research Data ◽  
Spearman Rank Correlation ◽  
Spearman Rank ◽  
Timber Products

In the study 100 boards of each cross-section have been measured with their subsequent certification and calculating the Spearman rank correlation coefficients on the principle “each with each”. Further data processing showed the existence of interdependencies between the location of defects on various sides of the timber cross-section. As a result of the research, data has been obtained allowing to change the current approach to sorting timber and to base normalization and quality assessment not on all four sides of timber, as being currently sorted, but only on one face and one edge.

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