Inhibitory effect of Anabaena sp. on in situ filtering rate of Daphnia

1986 ◽  
Vol 64 (9) ◽  
pp. 1831-1834 ◽  
Author(s):  
Patricia Chow-Fraser ◽  
W. Gary Sprules
Keyword(s):  
Lake Water ◽  
Laboratory Experiments ◽  
Carapace Length ◽  
Daphnia Pulex ◽  
Biomass Concentration ◽  
Inhibitory Effect ◽  
Filtering Rate ◽  
Anabaena Sp ◽  
Filtering Rates

We found that in situ filtering rates of Daphnia spp. measured in a lake containing Anabaena were significantly lower than those measured in a filament-free lake. Even after accounting for the depressing effects of high nannoplankton biomass concentration, filtering rates in the lake with Anabaena were 64% lower than those from the filament-free lake. We also found that filtering rates for Daphnia pulex in laboratory experiments were lower when Anabaena was present in experimental beakers than when Chlorella was present. When Anabaena was removed from Three Mile Lake water, filtering rates compared closely with predicted rates based on nannoplankton concentration and carapace length alone. Our analysis indicates that the presence of Anabaena filaments depresses Daphnia grazing rates in general, and that the filaments themselves are ingested at a lower rate than algae such as Chlorella.

Factors Regulating in situ Filtering Rates of Cladocera

1985 ◽  
Vol 42 (3) ◽  
pp. 567-576 ◽  
Author(s):  
Patricia Chow-Fraser ◽  
Roy Knoechel
Keyword(s):  
Regression Analysis ◽  
Carapace Length ◽  
Linear Regression Analysis ◽  
Filtering Rate ◽  
Independent Variable ◽  
Explained Variance ◽  
Main Determinants ◽  
Taxonomic Affiliation ◽  
Filtering Rates

Individual filtering rates of four species of Daphnia, as well as Holopedium, Diaphanosoma, Ceriodaphnia, and Bosmina, were measured in 10 lakes under various field conditions to identify important factors regulating in situ filter-feeding for these cladocerans. Linear regression analysis indicated that carapace length accounted for almost 60% of the total variance in individual filtering rates when data from all 10 lakes were pooled. We suggest that zooplankton in these lakes filter-feed in proportion to their volume, since the functional slope of this regression approximated 3. Taxonomic affiliation had generally little effect on filtering rates. Temperature, ranging from 12 to 22 °C, had no statistically significant effect on filtering rate; there were also no significant differences between rates measured at dawn and dusk compared with midday rates for animals ranging in size between 0.30 and 1.30 mm. Addition of phytoplankton concentration as a second independent variable to the regression relating filtering rate to length further increased explained variance to 64%. Since the two main determinants of in situ filtering rates were zooplankton carapace length and concentration of edible phytoplankton, both of which are independent of taxonomic affiliation, investigators interested in assessing grazing losses should seriously consider measuring zooplankton in terms of size distribution rather than taxonomic affiliation.

Feeding and respiration in the copepod Temora longicornis (Müller)

1962 ◽  
Vol 42 (3) ◽  
pp. 625-640 ◽  
Author(s):  
Ågot Berner
Keyword(s):  
Seasonal Variation ◽  
Laboratory Experiments ◽  
Feeding Experiments ◽  
Filtering Rate ◽  
Temora Longicornis ◽  
Winkler Method ◽  
Filtering Rates ◽  
Clyde Sea ◽  
Sea Area ◽  
Very High

Laboratory experiments on feeding and respiration were carried out with the copepod Temora longicornis in the Clyde sea-area. In feeding experiments, a method using radiophosphorus as a tracer was employed. The filtering rate was very variable and is probably related to size. There seemed to be a seasonal variation in filtering rates. During the summer of 1961 weekly water samples were taken for estimation of the particulate carbohydrate in the sea. There was always enough food present for Temora. Respiration was measured by using a modified Winkler method. Oxygen consumption was related to surface area, and corrections in respiratory rates were made for the size differences in the animals used. Respiratory rates were very high at the beginning of an experiment, but after a sharp fall the rate became steady in about 30 h. An indication of seasonal variation in oxygen uptake was found.

Filtering Rate Performance of Daphnia retrocurva in Pulp Mill Effluent

1977 ◽  
Vol 34 (6) ◽  
pp. 863-868 ◽  
Author(s):  
John M. Cooley
Keyword(s):  
Exposure Time ◽  
Lake Water ◽  
Laboratory Experiments ◽  
Pulp Mill ◽  
Pulp Mill Effluent ◽  
Rate Performance ◽  
Filtering Rate

Laboratory experiments were carried out with radioactive Scenedesmus to determine the effect on filtering rate of Daphnia retrocurva of exposure to different dilutions of raw pulp mill effluent in lake water. Filtering rate decreased progressively as the exposure time in 5 and 10% effluent increased. Most animals seemed able to recover from brief exposures, but with increased time spent in effluent, larger proportions of the animals did not filter when the food was presented.

scholarly journals Application of Furcellaran Nanocomposite Film as Packaging of Cheese

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1428
Author(s):  
Agnieszka Pluta-Kubica ◽  
Ewelina Jamróz ◽  
Gohar Khachatryan ◽  
Adam Florkiewicz ◽  
Pavel Kopel
Keyword(s):  
Silver Nanoparticles ◽  
Nanocomposite Film ◽  
Microbiological Quality ◽  
Inhibitory Effect ◽  
Quality Properties ◽  
In Situ Method ◽  
And Migration ◽  
Total Bacteria

There is a serious need to develop and test new biodegradable packaging which could at least partially replace petroleum-based materials. Therefore, the objective of this work was to examine the influence of the recently developed furcellaran nanocomposite film with silver nanoparticles (obtained by an in situ method) on the quality properties of two cheese varieties: a rennet-curd (gouda) and an acid-curd (quark) cheese. The water content, physicochemical properties, microbiological and organoleptic quality of cheese, and migration of silver nanoparticles were examined. Both the number of Lactococcus and total bacteria count did not differ during storage of gouda regardless of the packaging applied. The number of Lactococcus decreased in analogous quark samples. The use of the film slowed down and inhibited the growth of yeast in gouda and quark, respectively. An inhibitory effect of this film on mold count was also observed; however, only regarding gouda. The level of silver migration was found to be lower in quark than in gouda. The film improved the microbiological quality of cheeses during storage. Consequently, it is worth continuing research for the improvement of this film in order to enable its use in everyday life.

scholarly journals CircAgtpbp1 Acts as a Molecular Sponge of miR-543-5p to Regulate the Secretion of GH in Rat Pituitary Cells

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 558
Author(s):  
ZeWen Yu ◽  
WenZhi Ren ◽  
Tian Wang ◽  
WeiDi Zhang ◽  
ChangJiang Wang ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Inhibitory Effect ◽  
Pituitary Cells ◽  
Sequencing Analysis ◽  
Hormone Regulation ◽  
Gh Secretion ◽  
Qrt Pcr ◽  
Rat Pituitary ◽  
Rat Pituitary Cells

CircRNAs have been identified to be expressed differently and stably in numerous species and tissues, but their functions in growth hormone (GH) secretion are still largely unknown. In summary, we have revealed a circRNA-miRNA-mRNA network that may play a biological role in the rat pituitary gland. First, we verified the chromosome location information of circAgtpbp1 according to sequencing analysis. The circAgtpbp1 characteristics were authenticated through PCR, qRT–PCR, treating with RNase and fluorescent in situ hybridization (FISH). Second, we detected the expression pattern of circAgtpbp1 in the rat anterior pituitary by qRT–PCR. We also designed circAgtpbp1 siRNA and constructed overexpression plasmid to evaluate the effect of circAgtpbp1 function on GH secretion by qRT–PCR, ELISA and Western blot. CircAgtpbp1 is a stable, truly circular molecule. We found that circAgtpbp1 interacted with miR-543-5p and can regulate GH secretion in pituitary cells through a circAgtpbp1-miR-543-5p-GH axis. Overall, the evidence generated by our study suggests that circAgtpbp1 can act as a sponge of miR-543-5p to reduce the inhibitory effect of miR-543-5p on Gh1 and further promote GH secretion. These findings expand our existing knowledge on the mechanisms of hormone regulation in the pituitary gland.

scholarly journals Listener-Position and Orientation Dependency of Auditory Perception in an Enclosed Space: Elicitation of Salient Attributes

2021 ◽  
Vol 11 (4) ◽  
pp. 1570
Author(s):  
Bogdan Ioan Băcilă ◽  
Hyunkook Lee
Keyword(s):  
Auditory Perception ◽  
Laboratory Experiments ◽  
Head Orientation ◽  
Repertory Grid Technique ◽  
Apparent Source ◽  
Grid Technique ◽  
Subjective Study ◽  
Enclosed Space ◽  
Orientation Dependency

This paper presents a subjective study conducted on the perception of auditory attributes depending on listener position and head orientation in an enclosed space. Two elicitation experiments were carried out using the repertory grid technique—in-situ and laboratory experiments—which aimed to identify perceptual attributes among 10 different combinations of the listener’s positions and head orientations in a concert hall. It was found that, between the in-situ and laboratory experiments, the listening positions and head orientations were clustered identically. Ten salient perceptual attributes were identified from the data obtained from the laboratory experiment. Whilst these included conventional attributes such as ASW (apparent source width) and LEV (listener envelopment), new attributes such as PRL (perceived reverb loudness), ARW (apparent reverb width) and Reverb Direction were identified, and they are hypothesised to be sub-attributes of LEV (listener envelopment). Timbral characteristics such as Reverb Brightness and Echo Brightness were also identified as salient attributes, which are considered to potentially contribute to the overall perceived clarity.

scholarly journals Natural dimethyl sulfide gradients would lead marine predators to higher prey biomass

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Kylie Owen ◽  
Kentaro Saeki ◽  
Joseph D. Warren ◽  
Alessandro Bocconcelli ◽  
David N. Wiley ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Dimethyl Sulfide ◽  
Zooplankton Biomass ◽  
Foraging Success ◽  
Spatially Correlated ◽  
Prey Biomass ◽  
Marine Predators ◽  
Predator Foraging ◽  
The Impact

AbstractFinding prey is essential to survival, with marine predators hypothesised to track chemicals such as dimethyl sulfide (DMS) while foraging. Many predators are attracted to artificially released DMS, and laboratory experiments have shown that zooplankton grazing on phytoplankton accelerates DMS release. However, whether natural DMS concentrations are useful for predators and correlated to areas of high prey biomass remains a fundamental knowledge gap. Here, we used concurrent hydroacoustic surveys and in situ DMS measurements to present evidence that zooplankton biomass is spatially correlated to natural DMS concentration in air and seawater. Using agent simulations, we also show that following gradients of DMS would lead zooplankton predators to areas of higher prey biomass than swimming randomly. Further understanding of the conditions and scales over which these gradients occur, and how they are used by predators, is essential to predicting the impact of future changes in the ocean on predator foraging success.

Analysis of the World's First Polymer Injectivity Test in a Carbonate Reservoir Under Extreme Harsh Conditions in ADNOC's Reservoirs

2021 ◽  
Author(s):  
Juan Manuel Leon ◽  
Shehadeh K. Masalmeh ◽  
Siqing Xu ◽  
Ali M. AlSumaiti ◽  
Ahmed A. BinAmro ◽  
...  
Keyword(s):  
High Temperature ◽  
Laboratory Experiments ◽  
High Salinity ◽  
Laboratory Data ◽  
Injection Pressure ◽  
Carbonate Reservoir ◽  
Experimental Program ◽  
Full Field ◽  
Harsh Conditions

Abstract Assessing polymer injectivity for EOR field applications is highly important and challenging. An excessive injectivity reduction during and after polymer injection may potentially affect the well integrity and recovery efficiency and consequently, injection strategy and the economics of the polymer projects. Moreover, well conditions such as skin, completion configuration, and injection water quality can significantly impact polymer injectivity. Additionally, the presence of fractures or micro-fractures may govern injection pressure. In contrast, historic field applications have shown that polymer injectivity is in general better than expected from simulations or laboratory data. In the laboratory experiments, the polymer injectivity has been evaluated by injection of significant amounts of pore volumes of polymer at relevant well-injection rates. In addition, several experiments were performed to measure the complex in-situ rheology expected to dominate the flow near the wellbore This paper presents the analysis of the the world's first polymer injectivity test (PIT) conducted in a high temperature and high salinity (HTHS) carbonate reservoir in Abu Dhabi as part of a comprehensive de-risking program for a new polymer-based EOR scheme proposed by ADNOC for these challenging carbonate reservoirs (see Masalmeh et. al., 2014). The de-risking program includes an extensive laboratory experimental program and field injectivity test to ensure that the identified polymer can be injected and propagated in the target formation before multi-well pilot and full-field implementation stages. Experimental laboratory data and the field injectivity test results are presented in earlier publications (Masalmeh et. al., 2019; Rachapudi et. al., 2020) and references therein. This PIT is the world's first polymer injectivity test in a carbonate reservoir under such harsh conditions of high salinity, high content of divalent ions and high temperature. In addition, the polymer used during the test has never been field-tested before. Therefore, the results of the PIT interpretation will help to de-risk the suitable polymer for the future inter-well pilot for the new proposed EOR Polymer-based scheme and it is a game-changer to unlock several opportunities for different Chemical EOR applications on full-field scale in other reservoirs with similar characteristics. A single well radial simulation model was built to integrate the surveillance data during PIT and the extensive laboratory experiments. Morever, multiple Pressure Fall Off Tests (PFOs) during the same periods were analyzed and intergaretd in the model.The study assessed the effect of polymer viscosity on mobility reduction, evaluated the polymer bank propagation, investigated the effect of the skin build-up, residual resistance factor (RRF) and shear effects on the well injectivity. Additionally, a comprehensive assisted history match method and robust simulation sensitivity analysis was implemented, thousands of sensitivity simulation runs were performed to capture several possible injection scenarios and validate laboratory parameters. The simulation study confirmed that the PIT could be interpreted using the laboratory-measured polymer parameters such as polymer bulk viscosity, in-situ rheology, RRF and adsorption.

Sign in / Sign up

Export Citation Format

Share Document