Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 7

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  streams
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
The presence of chironomids and/or oligochaetes is generally considered to be an indication of poor status of freshwater. Non-chironomid dipterans show unclear trends. The abundance and percentage of these groups are rarely used as potential indicators. We attempted to determine whether these metrics reveal freshwater quality in lowland streams and lake littoral (Northern Europe, Baltic ecoregion, Estonia). The water quality was assessed based either on the water itself or on macroinvertebrates, fish, macrophytes, phytobenthos (in streams only) and/or phytoplankton (in lakes only). As expected, the high abundance and high percentage of chironomids and ceratopogonids indicated low quality of water in lakes. The high percentage of chironomids indicated low water quality also in streams. The high percentage of oligochaetes indicated low water quality in lakes. However, their high abundance (but not the percentage) was unexpectedly a symptom of high water quality in streams and to a lesser extent in lakes. In these cases, oligochaetes were represented by rheophilic, rather than saprophilic species. The abundance of simuliids (but not the percentage) and the richness of dipteran families indicated high water quality in streams. We suggest that the obtained results will allow better use of the indicative potential of freshwater macroinvertebrates.
EN
Diatoma polonica, a species first observed in samples from the Western Carpathians river systems in southern Poland, is described as a species new to science. The new species status resulted from the fact that the dimensions of cells found did not fit any of the diagnoses given in the literature for the European Diatoma taxa established so far. The genus is rather species-poor, even when the entire Holarctic flora is taken into account. The new species is morphologically closest to Diatoma moniliformis Kützing, particularly with respect to the vague resemblance of the valve outlines and the presence of a rimportula in each valve pole. Further, more or less similar taxa are D. tenuis Agardh, D. problematica Lange-Bertalot and D. mesodon (Ehrenberg) Kützing, all distinguished, in addition to other specific characteristics, by the rimoportulae regularly present at only one valve pole. Characteristics of D. polonica are described and compared with those of other species based on light and scanning electron microscopy.
PL
Materia organiczna stanowi ważne źródło energii w ekosystemach wód płynących. Do jej rozkładu zużywane są duże ilości tlenu rozpuszczonego, co w przypadku małych cieków może prowadzić do zbyt dużego zużycia tlenu, a w konsekwencji nawet do ich degradacji. Przykładem takiego małego cieku jest Osówka, który z uwagi na swoje położenie (w północnej części Szczecina) i otoczenie (lasy bukowe) przyjmuje duże ilości materii organicznej. Jest to silnie zmodyfikowany antropogenicznie ciek na Pomorzu Zachodnim, płynący na terenie zespołu przyrodniczo krajobrazowego "Dolina Siedmiu Młynów i źródła strumienia Osówka" znajdującego się w granicach administracyjnych miasta Szczecina (województwo zachodniopomorskie). Badania mające na celu określenie obciążenia wód Osówki materią organiczną prowadzono w roku 2009. Stwierdzono, że zawartość materii organicznej w wodach cieku Osówka zmieniała się sezonowo, a jej ilości nie pogarszały jakości wody, wpływając na możliwości produkcyjne cieku i podnosiły bioróżnorodność organizmów tam występujących. Dało się również zauważyć wpływ temperatury na szybkość rozkładu materii organicznej.
EN
The inanimate organic matter is an important source of energy in the flowing water ecosystems. For its decomposition a large amounts of dissolved oxygen is consumed, which in the case of small watercourses can lead to too high oxygen consumption and consequently even to their degradation. As an example of such small watercourse is Osówka stream, which due to its location (in the northern part of Szczecin) and surroundings (beech forest) absorbs a large amount of organic matter. It is a considerably anthropogenically modified watercourse in Western Pomerania, flowing in the area of the landscape and nature protected complex “Valley of the Seven Mills and the source of the Osówka stream” located within the administrative boundaries of Szczecin (Western Pomeranian Province). Scientific studies that determined the weight-load of organic matter in the water of Osówka stream were carried out in 2009. It was found that the content of organic matter in waters of Osówka stream had changed seasonally, and the amount of organic matter did not worsened the quality of water, but it actually affected the production capacity of the watercourse as well as it raised up the biological variety of organisms that occur there. The influence of temperature on the rate of decomposition process of the organic matter was also noted.
EN
We studied the fish assemblages of thirty one, 2nd-4th order "least-impacted" streams with a varying degree of low-level management in central Portugal, using a standardised survey to document the river habitat. Channel, banks and riparian landuse, described separately according to principal component scores, were significantly related to altitude, slope and management intervention. Species diversity was low, represented by four endemic, four pan-European and one exotic species. TWINSPAN classification distinguished 3 community types, characterised by their dominant species: trout (Salmo trutta L.), chub (Leuciscus carolitertii Doadrio) and "roach" (Squalius alburnoides Steindachner and Chondrostoma oligolepis Robalo). Community types were associated with environmental differences with PC Channel scores higher at trout sites compared to other classification groups, whilst PC Bank-1 scores, temperature and conductivity were significantly different at trout compared to "roach" sites. Ecologically important habitat features were, in turn, related to landscape (map-derived) parameters and the extent of channel and bank management. The mis-classification of sites in discriminant analysis was related to management intervention, indicating the potential difficulty in the assignment river-community types for the biological monitoring of fish communities in these stream types.
EN
Resource heterogeneity in the lake littoral zones and streams often takes the form of leaf litter diversity. Since resource quality varies between leaf species, diversity of leaf litter inputs to these systems may alter detritivore dynamics. We challenged the assumption that stream detritivores view their leaf resources independently, and that shredder colonization dynamics were additive. We developed a null model that suggests the temporal coefficient of variation in abundance of detritivores declines as leaf diversity increases. We then conducted an experiment in which leaf composition was manipulated in a stream and shredder abundance was followed. Shredder stability was low on single leaf species, increased at intermediate levels, then declined at maximum levels. The null model did not predict the low stability observed, suggesting other ecological factors influenced shredder abundance. Non-additive patterns in colonization support the notion that leaf diversity leads to emergent properties, altering consumer dynamics in this ecosystem.
EN
Pulse oximetry is a non-invasive measurement method of an arterial blood oxygen saturation. Pulse oximeter is one of the main bedside monitors used in neonatal units. The dispersed location of medical devices in such unit renders impossible to make a fast and valid decision in the case of simultaneous alarming situation. This paper present hardware and software structure of centralised neonatal monitoring system. Presented system can work as a single central station for monitoring of up to twenty four patients. Application of central monitoring system decreases the risk of undetected patients live and health threats. Thanks to this system the medical stuff is less burdened by routine procedures; therefore the medical unit is perceived as child- and mother-friendly.
EN
This paper describes the main features of the DISCUS model for one-dimensional advection-dispersion computations in rivers, and describes its application to a short reach of The Murray Burn (a small stream in Edinburgh). DISCUS was calibrated using tracer data and an optimisation technique that uses a genetic algorithm. The optimised dispersion coefficients were found to increase from 0.25 to 2 m2/s in the flow range 16-261 l/s. The model was validated using tracer data not used in the calibration stage. It appears that transient storage does not play a major role in the transport of solutes in the reach that was modeled.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.