The relationship between TN:TP ratio and phytoplankton nutrient limitation in Yanghe Reservoir

2011 ◽  
Author(s):  
Cui Lituo ◽  
Li Zhiwei
Keyword(s):  
Nutrient Limitation ◽  
Tn:Tp Ratio ◽  
The Relationship

scholarly journals Prediction ofMicrocystisBlooms Based on TN:TP Ratio and Lake Origin

2008 ◽  
Vol 8 ◽  
pp. 558-572 ◽  
Author(s):  
Yoshimasa Amano ◽  
Motoi Machida ◽  
Hideki Tatsumoto ◽  
Dennis George ◽  
Sharon Berk ◽  
...  
Keyword(s):  
Trophic State ◽  
Distribution Curve ◽  
Eutrophic Lakes ◽  
Dissolved Air Flotation ◽  
Maximum Value ◽  
Volcanic Lakes ◽  
Lake Trophic State ◽  
Tn:Tp Ratio ◽  
The Relationship ◽  
Dissolved Air

We evaluated the relationship between TN:TP ratio andMicrocystisgrowth via a database that includes worldwide lakes based on four types of lake origin (dammed, tectonic, coastal, and volcanic lakes). We used microcosm and mesocosm for the nutrient elution tests with lake water and four kinds of sediment (nontreated, MgO sprinkling treated, dissolved air flotation [DAF] treated, and combined treated sediment) in order to control TN:TP ratio and to suppressMicrocystisgrowth.Microcystisgrowth was related to TN:TP ratio, with the maximum value at an optimum TN:TP ratio and the minimum values when the TN:TP ratios reached to 0 or ∞. The kurtosis of the distribution curve varied with the type of lake origin; the lowest kurtosis was found in dammed lakes, while the highest was found in volcanic lakes. The lake trophic state could affect the change in the kurtosis, providing much lower kurtosis at eutrophic lakes (dammed lakes) than that at oligotrophic lakes (volcanic lakes). The relationship between TN:TP ratio andMicrocystisgrowth could be explained by the nutrient elution tests under controlled TN:TP ratios through the various sediment treatments. A significant suppression ofMicrocystisgrowth of 70% could be achieved when the TN:TP ratios exceeded 21. Lake origin could be regarded as an index including morphological and geographical factors, and controlling the trophic state in lakes. The origin rather than trophic state for lakes could be considered as an important factor of TN:TP influences on Microcystis growth.

Use of the Morphoedaphic Index to Predict Nutrient Status and Algal Biomass in Some Canadian Lakes

1991 ◽  
Vol 48 (10) ◽  
pp. 1909-1918 ◽  
Author(s):  
Patricia Chow-Fraser
Keyword(s):  
Predictive Power ◽  
Nutrient Status ◽  
Trophic Levels ◽  
Published Data ◽  
Water Color ◽  
Chl A ◽  
Flushing Rate ◽  
Morphoedaphic Index ◽  
Tn:Tp Ratio ◽  
The Relationship

The underlying assumptions of the morphoedaphic index (MEI; total dissolved solids (TDS)/mean depth), which has been used to predict fish yields in lakes, and its power for predicting biomass at lower trophic levels were examined using published data. The assumptions included the relationship between mean depth of lakes and various hydrologic characteristics (flushing rate and stratification regime), water transparency characteristics (water color and turbidity), and the stoichiometric relationship among ions (expressed as a proportion between TDS and the concentration of primary nutrients, total phosphorus (TP) and total nitrogen (TN)). Although these basic assumptions could be supported empirically, the predictive power of the MEI became progressively weakened with increasing trophic level. MEI accounted for up to 85% of the variation in TP and TN, less than 50% of the variation in [Chl a], and none of the variation in the biomass of herbivorous zooplankton. The functions relating TDS to both TP and TN were fundamentally different: as lakes increased in salinity, the TN:TP ratio decreased dramatically so that TP almost exceeded TN concentrations in extremely saline lakes. This necessitated the development of separate MEI–nutrient relationships for saline (TDS > 1000 mg/L) and nonsaline lakes.

scholarly journals CodY-Dependent Regulation of Sporulation in Clostridium difficile

2016 ◽  
Vol 198 (15) ◽  
pp. 2113-2130 ◽  
Author(s):  
Kathryn L. Nawrocki ◽  
Adrianne N. Edwards ◽  
Nadine Daou ◽  
Laurent Bouillaut ◽  
Shonna M. McBride
Keyword(s):  
Clostridium Difficile ◽  
Nutrient Limitation ◽  
Negative Regulator ◽  
Pcr Analysis ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Sporulation Initiation ◽  
The Impact ◽  
The Relationship

ABSTRACTClostridium difficilemust form a spore to survive outside the gastrointestinal tract. The factors that trigger sporulation inC. difficileremain poorly understood. Previous studies have suggested that a link exists between nutritional status and sporulation initiation inC. difficile. In this study, we investigated the impact of the global nutritional regulator CodY on sporulation inC. difficilestrains from the historical 012 ribotype and the current epidemic 027 ribotype. Sporulation frequencies were increased in both backgrounds, demonstrating that CodY represses sporulation inC. difficile. The 027codYmutant exhibited a greater increase in spore formation than the 012codYmutant. To determine the role of CodY in the observed sporulation phenotypes, we examined several factors that are known to influence sporulation inC. difficile. Using transcriptional reporter fusions and quantitative reverse transcription-PCR (qRT-PCR) analysis, we found that two loci associated with the initiation of sporulation,oppandsinR, are regulated by CodY. The data demonstrate that CodY is a repressor of sporulation inC. difficileand that the impact of CodY on sporulation and expression of specific genes is significantly influenced by the strain background. These results suggest that the variability of CodY-dependent regulation is an important contributor to virulence and sporulation in current epidemic isolates. This report provides further evidence that nutritional state, virulence, and sporulation are linked inC. difficile.IMPORTANCEThis study sought to examine the relationship between nutrition and sporulation inC. difficileby examining the global nutritional regulator CodY. CodY is a known virulence and nutritional regulator ofC. difficile, but its role in sporulation was unknown. Here, we demonstrate that CodY is a negative regulator of sporulation in two different ribotypes ofC. difficile. We also demonstrate that CodY regulates known effectors of sporulation, Opp and SinR. These results support the idea that nutrient limitation is a trigger for sporulation inC. difficileand that the response to nutrient limitation is coordinated by CodY. Additionally, we demonstrate that CodY has an altered role in sporulation regulation for some strains.

Unifying Nutrient–Chlorophyll Relationships in Lakes

1989 ◽  
Vol 46 (7) ◽  
pp. 1176-1182 ◽  
Author(s):  
Yves T. Prairie ◽  
Carlos M. Duarte ◽  
Jacob Kalff
Keyword(s):  
Nutrient Limitation ◽  
Chlorophyll A ◽  
Nutrient Concentrations ◽  
Regression Equations ◽  
Independent Data ◽  
Nitrogen And Phosphorus ◽  
Nutrient Levels ◽  
Tn:Tp Ratio ◽  
Over Time

We used data drawn from the literature to test some basic predictions derived from nutrient limitation theory. Contrary to expectation, nitrogen was not better correlated to chlorophyll in nitrogen limited lakes (as measured by the total nitrogen:total phosphorus (TN:TP) ratio). We also examined whether the variability in published relationships between chlorophyll a (Chla) and nutrient levels in lakes can be explained by differences in the relative concentrations of nitrogen and phosphorus (TN:TP ratio). Our results show that the coefficients and precision of the Chla = f(TP) and Chla = f(TN) regression equations vary systematically and concomitantly with TN:TP ratios, and are highest for lakes with TN:TP ratios of 23–28 (by weight). These findings were confirmed with independent data and explain the variability of published Chla = f(TP) relationships. We propose a model that predicts the coefficients of Chla = f(TP) and Chla = f(TN) equations for lakes with different TN:TP ratios. This model proved useful in predicting the chlorophyll trajectories of lakes over time. The results imply an "optimal" TN:TP ratio beyond which the relative rates of increase in chlorophyll with increasing nutrient concentrations are reduced.

Eutrophication and nutrient limitation in the aquatic zones around Huainan coal mine subsidence areas, Anhui, China

2014 ◽  
Vol 70 (5) ◽  
pp. 878-887 ◽  
Author(s):  
Qitao Yi ◽  
Xiaomeng Wang ◽  
Tingting Wang ◽  
Xijie Qu ◽  
Kai Xie
Keyword(s):  
Nutrient Limitation ◽  
Coal Mine ◽  
Trophic Structure ◽  
Inorganic Nitrogen ◽  
Nutrient Content ◽  
Small Lakes ◽  
Eutrophic Lakes ◽  
Blue Green Algae ◽  
Mine Subsidence ◽  
Tn:Tp Ratio

The eutrophication of three small lakes in the aquatic zones at the Huainan coal mine subsidence areas, designated as east site (ES), central site (CS), and west site (WS), were studied. Nutrient content, species, and nitrogen (N) to phosphorus (P) ratios were obtained through water quality analyses. Nutrient limitation was evaluated by nutrient enrichment bioassays (NEBs) in the autumn of 2012 and spring of 2013. Average annual concentrations of total phosphorus (TP) were 0.05, 0.08, and 0.10 mg/L, and total nitrogen (TN) concentrations were 0.77, 1.95, and 2.06 mg/L in the water column at CS, ES, and WS, respectively. All of the three lakes exhibited ‘meso-eutrophic’ states and the TN:TP ratio ranged from 25:1 to 74:1 with variability between seasons and sites. NEBs verified that primary productivity in the lakes at ES and WS were mainly limited by P, while N limitation or N and P co-limitation was present in the aquatic zones at CS due to unavailable dissolved inorganic nitrogen. In the studied lakes, the blue-green algae, which comprised 70% of all identified species, was the predominant taxa, while the micro-zooplankton taxa was dominant, indicating a typical trophic structure of eutrophic lakes.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Choosing a Markov blanket

2020 ◽  
Vol 43 ◽  
Author(s):  
Thomas Parr
Keyword(s):  
Markov Blanket ◽  
Target Article ◽  
The Relationship

Abstract This commentary focuses upon the relationship between two themes in the target article: the ways in which a Markov blanket may be defined and the role of precision and salience in mediating the interactions between what is internal and external to a system. These each rest upon the different perspectives we might take while “choosing” a Markov blanket.

Tinkering with cognitive gadgets: Cultural evolutionary psychology meets active inference

2019 ◽  
Vol 42 ◽  
Author(s):  
Paul Benjamin Badcock ◽  
Axel Constant ◽  
Maxwell James Désormeau Ramstead
Keyword(s):  
Evolutionary Psychology ◽  
Research Program ◽  
Active Inference ◽  
Innovative Research ◽  
Cognitive Faculties ◽  
Cultural Evolutionary ◽  
The Relationship

Abstract Cognitive Gadgets offers a new, convincing perspective on the origins of our distinctive cognitive faculties, coupled with a clear, innovative research program. Although we broadly endorse Heyes’ ideas, we raise some concerns about her characterisation of evolutionary psychology and the relationship between biology and culture, before discussing the potential fruits of examining cognitive gadgets through the lens of active inference.

Radiation Damage, Contrast and Statistics in High Resolution Biological Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 260-261
Author(s):  
Robert M. Glaeser
Keyword(s):  
High Resolution ◽  
Particle Flux ◽  
Unit Area ◽  
Signal To Noise ◽  
Resolution Image ◽  
High Resolution Image ◽  
Pass Through ◽  
Counting Statistics ◽  
The Relationship ◽  
Picture Element

It is well known that a large flux of electrons must pass through a specimen in order to obtain a high resolution image while a smaller particle flux is satisfactory for a low resolution image. The minimum particle flux that is required depends upon the contrast in the image and the signal-to-noise (S/N) ratio at which the data are considered acceptable. For a given S/N associated with statistical fluxtuations, the relationship between contrast and “counting statistics” is s131_eqn1, where C = contrast; r2 is the area of a picture element corresponding to the resolution, r; N is the number of electrons incident per unit area of the specimen; f is the fraction of electrons that contribute to formation of the image, relative to the total number of electrons incident upon the object.

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