scholarly journals New and Fast Method To Quantify Respiration Rates of Bacterial and Plankton Communities in Freshwater Ecosystems by Using Optical Oxygen Sensor Spots

2007 ◽  
Vol 73 (21) ◽  
pp. 6722-6729 ◽  
Author(s):  
Mareike Warkentin ◽  
Heike M. Freese ◽  
Ulf Karsten ◽  
Rhena Schumann
Keyword(s):  
Oxygen Consumption ◽  
Respiration Rate ◽  
Bacterial Communities ◽  
Oxygen Sensor ◽  
Bacterial Isolate ◽  
Freshwater Ecosystems ◽  
New Method ◽  
Fast Method ◽  
Signal Drift ◽  
Eutrophic River

ABSTRACT A new method of respiration rate measurement based on oxygen luminescence quenching in sensor spots was evaluated for the first time for aquatic bacterial communities. The commonly used Winkler and Clark electrode methods to quantify oxygen concentration both require long incubation times, and the latter additionally causes signal drift due to oxygen consumption at the cathode. The sensor spots proved to be advantageous over those methods in terms of precise and quick oxygen measurements in natural bacterial communities, guaranteeing a respiration rate estimate during a time interval short enough to neglect variations in organism composition, abundance, and activity. Furthermore, no signal drift occurs during measurements, and respiration rate measurements are reliable even at low temperatures and low oxygen consumption rates. Both a natural bacterioplankton sample and a bacterial isolate from a eutrophic river were evaluated in order to optimize the new method for aquatic microorganisms. A minimum abundance of 2.2 � 106 respiring cells ml−1 of a bacterial isolate was sufficient to obtain a distinct oxygen depletion signal within 20 min at 20�C with the new oxygen sensor spot method. Thus, a culture of a bacterial isolate from a eutrophic river (OW 144; 20 � 106 respiring bacteria ml−1) decreased the oxygen saturation about 8% within 20 min. The natural bacterioplankton sample respired 2.8% from initially 94% oxygen-saturated water in 30 min. During the growth season in 2005, the planktonic community of a eutrophic river consumed between 0.7 and 15.6 μmol O2 liter−1 h−1. The contribution of bacterial respiration to the total plankton community oxygen consumption varied seasonally between 11 and 100%.

Bacterial presence in polar regions associated with environment modification by chemical compounds including contaminants

2017 ◽  
Vol 25 (4) ◽  
pp. 481-491 ◽  
Author(s):  
Klaudia Kosek ◽  
Katarzyna Jankowska ◽  
Żaneta Polkowska
Keyword(s):  
Bacterial Communities ◽  
Chemical Compounds ◽  
Freshwater Ecosystems ◽  
Trophic Levels ◽  
Polar Regions ◽  
Bacterial Cells ◽  
Chemical Contamination ◽  
Climate Conditions ◽  
Biological Communities ◽  
Long Time

Microbes are omnipresent and diverse members of all biological communities. In marine and freshwater ecosystems, microorganisms form the base of the food chain supporting higher trophic levels. Even though microbes are generally thought to live in warm regions of Earth, many of them develop in cold climates. Polar regions remain relatively protected from widespread anthropogenic disturbances, which is a consequence of thier remoteness and extreme climate conditions. For a long time these regions were considered to be free from chemical contamination until scientists discovered a presence of pollutants there. Chemical contamination may induce serious disorders in the integrity of polar ecosystems influencing the growth of bacterial communities. Xenobiotics including persistent organic pollutants are transported thousands of kilometers by the air and ocean currents, and they are deposed in high-latitude regions and accumulate in all elements of the environment including bacterial communities. It is important to determine their concentration levels in bacterial cells to assess the possibility of contaminants becoming transferred to higher trophic levels; however, some species of bacteria are capable of metabolizing xenobiotics, which makes them less toxic or even removes them from the environment.

Effect of growth rate on the physiological rates of a chemostat-grown rotifer Encentrum linnhei

1988 ◽  
Vol 68 (1) ◽  
pp. 165-177 ◽  
Author(s):  
J. M. Scott
Keyword(s):  
Growth Rate ◽  
Oxygen Consumption ◽  
Steady State ◽  
Respiration Rate ◽  
Clearance Rate ◽  
Ingestion Rate ◽  
Physiological State ◽  
Growth Efficiency ◽  
Theoretical Figure ◽  
Marine Rotifer

The physiological rates of a normally omnivorous marine rotifer, Encentrum linnhei, were measured under the steady-state chemostat conditions in which the physiological state of the food-algae was kept constant whilst the rotifer growth rate was changed to preset levels. The specific clearance rate ranged between 50 and 100 μl/μg rotifer C/day (1.5–3.0 μ/rot/day) and varied hyperbolically with growth rate, a similar curve was obtained with the specific ingestion rate which varied between 1–2 μg C/μg rot C/day. A mean respiration rate of 0.45 μg C/μg rot C/day was obtained from oxygen consumption measurements. About 60‰ of ingested energy was found to be egested as paniculate matter and 9–4 °0 dissipated as heat, the latter comparing with a theoretical figure of 4–5‰.From rates, transfer efficiencies were obtained giving a mean net growth efficiency (K2) of 38‰ and a mean overall growth efficiency (K1 of 15‰. A curvilinear increase of Kl with growth rate contrasts with linear and hyperbolic responses found with brachionid rotifers.

A Fast Method for Solving Contact Plasticity in a Half Space

2011 ◽  
Author(s):  
Zhanjiang Wang ◽  
Xiaoqing Jin ◽  
Shuangbiao Liu ◽  
Leon M. Keer ◽  
Jian Cao ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Residual Stresses ◽  
Fast Fourier Transform ◽  
Half Space ◽  
Three Dimensional ◽  
New Method ◽  
Fast Method ◽  
Discrete Convolution ◽  
Influence Coefficients ◽  
The One

This paper presents a new method of contact plasticity analysis based on Galerkin vectors to solve the eigenstresses due to eigenstrain. The influence coefficients relating eigenstrains to eigenstresses thus can be divided into four terms the one due to the eigenstrains in the full space, others due to the mirrored eigenstrains in the mirror half space. Each term can be solved fast and efficient by using the three-dimensional discrete convolution and fast Fourier transform (DC-FFT) or the three-dimensional discrete correlation and fast Fourier transform (DCR-FFT). The new method is used to analyze the contact plastic residual stresses in half space.

scholarly journals The Effect of Ionic Copper on the Oxygen Consumption of Gammarus Pulex and Polycelis Nigra

1941 ◽  
Vol 18 (2) ◽  
pp. 153-161
Author(s):  
J. R. ERICHSEN JONES
Keyword(s):  
Oxygen Consumption ◽  
Respiration Rate ◽  
Copper Sulphate ◽  
Muscular Activity ◽  
Gammarus Pulex ◽  
Cellular Respiration ◽  
Appreciable Effect ◽  
Normal Value ◽  
Ionic Copper ◽  
Effect Of Copper

The suggestion has been put forward that the oligodynamic action of certain heavy metals is the result of the destruction or inactivation of substances essential for cellular respiration. In a study of the effect of copper sulphate solutions on the oxygen consumption of Polycelis nigra it is found that solutions of concentration 0.001-0.01 N, fatal in 2 hr. or less, induce a marked preliminary rise in the respiration rate; this appears to be due to the inhibition of ciliary locomation and increased muscular activity. A similar increase is produced by increasing the activity of the animals by mechanical means, or by a muscle stimulant (barium chloride). Over the latter part of the survival time the respiration rate drops rapidly and disintegration of the animals begins when it falls to about 60% of the normal value. A 0.0004 N copper sulphate solutions does not inhibit ciliary locomotion, does not stimulate muscular activity, and the oxygen consumption undergoes a stedy decline. A 0.0002 N NaCN solution rapidly depresses the respiration rate to less than 20% of the normal value, but is not fatal, the animals surviving over 4 days. Hydrogen ions, at the concentrations resulting from the hydrolysis of the salt, have no appreciable effect on the oxygen consumption, but at lethal concentrations (pH 2.6, 2.8) effect a speedy depression. The results suggest that the depression of respiration rate observed is insufficient to account for the death of the animals, and is no more than a symptom of the toxic process. A similar general result was obtained in experiments with silver nitrate and mercuric chloride, and also in experiments on the comparative effect of copper sulphate and sodium cyanide solutions on the oxygen consumption of Gammarus pulex.

scholarly journals An electronic valve controller for current control during the recording of oxygen consumption in aquatic animals

1989 ◽  
Vol 8 (2) ◽  
pp. 74-76
Author(s):  
H. H. Du Preez ◽  
E. Grobler ◽  
J. M. Bell
Keyword(s):  
Oxygen Consumption ◽  
Control System ◽  
Oxygen Sensor ◽  
Aquatic Organisms ◽  
Current Control ◽  
Automatic Recording ◽  
Aquatic Animals ◽  
Power Circuit ◽  
Minute Period

A control system is described which allows the automatic recording of the oxygen consumption of five aquatic organisms and one control. The electronic valve controller operates six three-way valves which permit water from each of the six respiration chambers to flow successively past the oxygen sensor. A 38.4 kHz quartz cristal oscillator ensures a ten minute period and is not affected by disturbances on the power circuit.

Vertical and horizontal assemblage patterns of bacterial communities in a eutrophic river receiving domestic wastewater in southeast China

2017 ◽  
Vol 230 ◽  
pp. 469-478 ◽  
Author(s):  
Yan Gao ◽  
Chengcheng Wang ◽  
Weiguo Zhang ◽  
Panpan Di ◽  
Neng Yi ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Domestic Wastewater ◽  
Southeast China ◽  
Eutrophic River

scholarly journals A New Method for Measuring the Oxygen Diffusion Constant and Oxygen Consumption Rate of Arteriolar Walls

2012 ◽  
Vol 61 (2) ◽  
pp. 57-65 ◽  
Author(s):  
Nobuhiko Sasaki ◽  
Hirohisa Horinouchi ◽  
Akira Ushiyama ◽  
Haruyuki Minamitani
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Consumption Rate ◽  
Oxygen Diffusion ◽  
Consumption Rate ◽  
Diffusion Constant ◽  
New Method

scholarly journals Multiple Stressors Determine Community Structure and Estimated Function of River Biofilm Bacteria

2020 ◽  
Vol 86 (12) ◽  
Author(s):  
Ferran Romero ◽  
Vicenç Acuña ◽  
Sergi Sabater
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Communities ◽  
Pesticide Exposure ◽  
Multiple Stressors ◽  
Bacterial Community Composition ◽  
Freshwater Ecosystems ◽  
Low Flow ◽  
Hydrological Stress ◽  
The Individual

ABSTRACT Freshwater ecosystems are exposed to multiple stressors, but their individual and combined effects remain largely unexplored. Here, we investigated the response of stream biofilm bacterial communities to warming, hydrological stress, and pesticide exposure. We used 24 artificial streams on which epilithic (growing on coarse sediments) and epipsammic (growing on fine sediments) stream biofilms were maintained. Bacterial community composition and estimated function of biofilms exposed during 30 days to individual and combined stressors were assessed using 16S rRNA gene metabarcoding. Among the individual effects by stressors, hydrological stress (i.e., a simulated low-flow situation) was the most relevant, since it significantly altered 57% of the most abundant bacterial taxa (n = 28), followed by warming (21%) and pesticide exposure (11%). Regarding the combined effects, 16% of all stressor combinations resulted in significant interactions on bacterial community composition and estimated function. Antagonistic responses prevailed (57 to 89% of all significant interactions), followed by synergisms (11 to 43%), on specific bacterial taxa, indicating that multiple-stressor scenarios could lead to unexpected shifts in the community composition and associated functions of riverine bacterial communities. IMPORTANCE Freshwater ecosystems such as rivers are of crucial importance for human well-being. However, human activities result in many stressors (e.g., toxic chemicals, increased water temperatures, and hydrological alterations) cooccurring in rivers and streams worldwide. Among the many organisms inhabiting rivers and streams, bacteria are ecologically crucial; they are placed at the base of virtually all food webs and they recycle the organic matter needed for bigger organisms. Most of these bacteria are in close contact with river substratum, where they form the biofilms. There is an urgent need to evaluate the effects of these stressors on river biofilms, so we can anticipate future environmental problems. In this study, we experimentally exposed river biofilms to a pesticide mixture, an increase in water temperature and a simulated low-flow condition, in order to evaluate the individual and joint effects of these stressors on the bacterial community composition and estimated function.

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