Interactive Effects of Nutrient Availability and Light Levels on the Periphyton Composition of a Large Oligotrophic Lake

1993 ◽  
Vol 50 (6) ◽  
pp. 1270-1278 ◽  
Author(s):  
Jane Claire Marks ◽  
Rex L. Lowe
Keyword(s):  
Interactive Effect ◽  
Oligotrophic Lake ◽  
Interactive Effects ◽  
Nitrogen And Phosphorus ◽  
Phosphorus Enrichment ◽  
Blue Green Algae ◽  
Nitzschia Palea ◽  
Nitrogen Levels ◽  
Light Levels ◽  
Nitrogen Phosphorus

We investigated the effects of nitrogen, phosphorus, and light on periphyton in a clear oligotrophic lake. Experimental treatments consisted of three levels each of nitrogen, phosphorus, and light in a three-way factorial design. Nitrogen and phosphorus concentrations were manipulated using nutrient-diffusing clay substrates; light levels were manipulated with shade cloth. Periphyton biovolume and cell densities increased significantly with both nitrogen and phosphorus enrichment but were not affected by shading. Phosphorus enrichment increased periphyton accumulation only when nitrogen levels were high, indicating a significant interactive effect between nitrogen and phosphorus. Differences in species composition among treatments were mostly due to changes in the diatoms Nitzschia palea and Rhopalodia gibba. Ambient and phosphorus-enriched substrates were dominated by R. gibba, which contains a nitrogen-fixing endosymbiont, and blue-green algae. Nitrogen enrichment and nitrogen and phosphorus in combination resulted in an assemblage dominated by N. palea. Unshaded and highly shaded substrates were dominated by N. palea and Achnanthes minutissima, but the medium-shade substrates were dominated by R. gibba.

scholarly journals DESENVOLVIMENTO DE MUDAS DE Swietenia macrophylla EM RESPOSTA A NITROGÊNIO, FÓSFORO E POTÁSSIO

FLORESTA ◽  
2011 ◽  
Vol 41 (3) ◽  
Author(s):  
Carlos Alberto Franco Tucci ◽  
José Zilton Lopes Santos ◽  
Clauzio Heitor da Silva Júnior ◽  
Patrícia Aparecida de Souza ◽  
Iza Maria Paiva Batista ◽  
...  
Keyword(s):  
Dry Weight ◽  
Swietenia Macrophylla ◽  
Nitrogen And Phosphorus ◽  
Nitrogen Levels ◽  
Phosphorus And Potassium ◽  
Red Latosol ◽  
Para Determinar ◽  
Nitrogen Phosphorus ◽  
Phosphorus Levels

Objetivou-se avaliar neste estudo o efeito de nitrogênio, fósforo e potássio no crescimento de mudas de mogno. As plantas foram cultivadas num Latossolo Amarelo Distrófico argiloso com seis níveis de nitrogênio (0, 50, 100, 125, 150 e 200 kg N ha-1), seis níveis de fósforo (0, 75, 150, 225, 300 e 400 kg P2O5 ha-1) e seis níveis de potássio (0, 40, 80, 120, 160 e 200 kg K ha-1), em condição de casa de vegetação. Aos 100 dias após o transplantio, as plantas foram colhidas para determinar as características de crescimento: altura, diâmetro, matéria seca da parte aérea e raízes e a concentração de nutrientes presentes na parte aérea e raízes. O desenvolvimento das mudas de mogno é pouco influenciado pelo fornecimento de doses crescentes dos nutrientes nitrogênio, fósforo e potássio, indicando uma baixa exigência nutricional da espécie na fase inicial de crescimento. Entre os nutrientes avaliados, a espécie parece ligeiramente mais exigente quanto ao potássio em relação aos demais. No entanto, a demanda da planta já seria satisfeita com uma pequena adição do respectivo nutriente. A adubação com nitrogênio e fósforo não promove melhora na qualidade das mudas de mogno.Palavras-chave: Espécies florestais; mogno; nutrição mineral; crescimento inicial. AbstractDevelopment of Swietenia macrophylla seedlings in response to nitrogen, phosphorus and potassium. A Greenhouse experiment was developed in order to investigate effects of nitrogen, phosphorus and potassium on the growth of mahogany seedlings (Swietenia macrophylla King). The plants were cultured in clayey dystrophic Red Latosol containing six nitrogen levels (0, 50, 100, 125, 150 and 200 kg N ha-1), six phosphorus levels (0, 75, 150, 225, 300 and 400 kg P2O5 ha-1) and six potassium levels (0, 40, 80, 120, 160 and 200 kg K ha-1). After 100 days of transplanting, the plants were harvest and processed for determine height, diameter, dry weight and nutrient concentration in roots and shoots. Addition of nitrogen, phosphorus and potassium did not affect the mahogany seedlings development. In contrast to N and P, the yield of plants was slightly greater with K fertilization. In general, results of this study clearly demonstrate the absence of a beneficial effect of these nutrients on the growth of mahogany seedlings. The nitrogen and phosphorus did not improve the quality of mahogany seedlings.Keywords: Forest species; mahogany; mineral nutrition; early growth.

scholarly journals DETERMINATION OF THE TROPICAL STATUS OF FLOATING NET CAGE WATER BASED ON THE DISTRIBUTION OF NITROGEN, PHOSPHORUS AND CHLOROPHYLL-A

2021 ◽  
Vol 7 (2) ◽  
pp. 172-184
Author(s):  
Peni Pujiastuti ◽  
Roesleini J Putri ◽  
Suseno Suseno
Keyword(s):  
Chlorophyll A ◽  
Laboratory Data ◽  
Fish Feed ◽  
Nitrogen And Phosphorus ◽  
Nitrogen Levels ◽  
Net Cage ◽  
Net Cages ◽  
Chlorophyll A Content ◽  
Nitrogen Phosphorus

The dominant source of pollutants for floating net cages are fish feed and feces. They cause phosphorus and nitrogen in water increase, trigger eutrophication, marked by the appearance of algae. Algae are green plants, contain chlorophyll-a. The content of phosphorus, nitrogen and chlorophyll-a can be used to determine the tropical status of water. The objective of this research is to determine the tropical status of marine cage water. The research method was descriptive laboratory. Nitrogen content is measured as nitrite according to SNI 6989.9-2004, nitrate according to APHA Section 4500-NO3, ammonia according to SNI 19-1655-1989. Phosphorus analysis according to SNI 06-6989-31: 2005. Chlorophyll-a analysis used the Strickland & Parson method by spectrophotometry. Laboratory data were analyzed for tropical status based on nitrogen, phosphorus and chlorophyll-a content. The results showed that the tropical status of the KJA water of Gajah Mungkur Reservoir Wonogiri in the rainy season had eutrophic status, containing high levels of phosphorus and nitrogen elements. The eutrophic status indicated  that the water had been polluted by an enhancement of  nitrogen levels by 18.345 µg/L and phosphorus by 420.65 µg/L. These nitrogen and phosphorus pollutants increased the growth of chlorophyll-a by 12.70 µg/L.

Interactive toxic effects of agrochemicals on aquatic organisms

1999 ◽  
Vol 40 (1) ◽  
pp. 357-364 ◽  
Author(s):  
A. Kungolos ◽  
P. Samaras ◽  
A. M. Kipopoulou ◽  
A. Zoumboulis ◽  
G. P. Sakellaropoulos
Keyword(s):  
Daphnia Magna ◽  
Marine Bacterium ◽  
Methyl Parathion ◽  
Vibrio Fischeri ◽  
Interactive Effect ◽  
Algal Growth ◽  
Aquatic Organisms ◽  
Interactive Effects ◽  
Selenastrum Capricornutum ◽  
Toxic Compound

The effects of three common agrochemicals, lindane, methyl parathion and atrazine, on crustacean Daphnia magna, alga Selenastrum capricornutum and marine bacterium Vibrio fischeri were investigated in this study. Methyl parathion was the most toxic compound towards all three organisms, while lindane was more toxic to Daphnia magna and Vibrio fischeri than atrazine, and atrazine was more toxic to Selenastrum capricornutum than lindane. Among the three aquatic organisms, Selenastrum capricornutum was most sensitive in detecting lindane and atrazine toxicity, while Daphnia magna was most sensitive in detecting methyl parathion toxicity. The interactive effects of the pesticides were also investigated. The interactive effect between lindane and methyl parathion on survival of Daphnia magna was synergistic, while the ones between lindane and atrazine and between methyl parathion and atrazine were generally additive. The interactive effect of the three pesticides applied together on Daphnia magna was synergistic. The interactive effect of the three pesticides on the growth of Selenastrum capricornutum was antagonistic with few cases of addition, while the effect of all the three pairs of pesticides on algal growth was also antagonistic. The interactive effect of lindane and methyl parathion on Vibrio fischeri was additive.

Categorization flexibility and unconventional choices: is life an adventure?

2020 ◽  
Vol 54 (8) ◽  
pp. 1963-1986
Author(s):  
Tilottama G. Chowdhury ◽  
Feisal Murshed
Keyword(s):  
Interactive Effect ◽  
Interactive Effects ◽  
Cognitive Capacity ◽  
Purchase Behavior ◽  
Consumer Decision Making ◽  
Cross Sectional ◽  
Content Type ◽  
Cross Domain ◽  
Multiple Domains

Purpose This paper proposes that categorization flexibility, operationalized as the cognitive capacity that cross-categorizes products in multiple situational categories across multiple domains, might favorably influence a consumer’s evaluation of unconventional options. Design/methodology/approach Experimental research design is used to test the theory. An exploratory study first establishes the effect of categorization flexibility in a non-food domain. Study 1 documents the moderating role of decision domain, showing that the effect works only under low- (vs high-) consequence domain. Studies 2A and 2B further refine the notion by showing that individuals can be primed in a relatively higher categorization flexibility frame of mind. Study 3 demonstrates the interactive effect of categorization flexibility and adventure priming in a high-consequence domain. Study 4 integrates the interactive effects of decisions with low- vs high-consequence, adventure priming and categorization flexibility within a single decision domain of high consequence. Findings Consumers with higher- (vs lower-) categorization flexibility tend to opt for unconventional choices when the decision domain entails low consequences, whereas such a result does not hold under decision domain of high consequences. The categorization flexibility effects in case of low-consequence decision domain holds true even when consumers are primed to be categorization flexible. Furthermore, with additional adventure priming, consumers show an increased preference for unconventional options even under a decision domain with high consequence. Research limitations/implications This study could not examine real purchase behavior as results are based on cross-sectional, behavioral intention data. In addition, it did not examine the underlying reason for presence of cross-domain categorization flexibility index. Practical implications The results suggest that stimuli may be tailored to consumers in ways that increase the salience and the perceived attractiveness of unconventional choices. Further, data reinforce the notion of cross-categorical interrelations among different domains, which could be leveraged by marketers. Originality/value This study represents the first documentation of the potential ways by which unconventional product choice might be a function of individuals’ categorization flexibility level across different types of decision domains. The findings yield implications that are novel to both categorization and consumer decision-making literature.

scholarly journals The SN2 reaction and its relationship with the Walden inversion, the Finkelstein and Menshutkin reactions together with theoretical calculations for the Finkelstein reaction

2021 ◽  
Author(s):  
Ibon Alkorta ◽  
José Elguero
Keyword(s):  
Linear Models ◽  
Theoretical Calculations ◽  
Computational Method ◽  
Basis Set ◽  
Free Energies ◽  
Nitrogen And Phosphorus ◽  
Atom Pairs ◽  
Leaving Groups ◽  
First Time ◽  
Nitrogen Phosphorus

AbstractThis communication gives an overview of the relationships between four reactions that although related were not always perceived as such: SN2, Walden, Finkelstein, and Menshutkin. Binary interactions (SN2 & Walden, SN2 & Menshutkin, SN2 & Finkelstein, Walden & Menshutkin, Walden & Finkelstein, Menshutkin & Finkelstein) were reported. Carbon, silicon, nitrogen, and phosphorus as central atoms and fluorides, chlorides, bromides, and iodides as lateral atoms were considered. Theoretical calculations provide Gibbs free energies that were analyzed with linear models to obtain the halide contributions. The M06-2x DFT computational method and the 6-311++G(d,p) basis set have been used for all atoms except for iodine where the effective core potential def2-TZVP basis set was used. Concerning the central atom pairs, carbon/silicon vs. nitrogen/phosphorus, we reported here for the first time that the effect of valence expansion was known for Si but not for P. Concerning the lateral halogen atoms, some empirical models including the interaction between F and I as entering and leaving groups explain the Gibbs free energies.

Nutrients and phytoplankton in three shallow, freshwater lakes of different tropic status in Western Australia

1981 ◽  
Vol 32 (4) ◽  
pp. 541 ◽  
Author(s):  
DM Gordon ◽  
CM Finlayson ◽  
AJ McComb
Keyword(s):  
Green Algae ◽  
Western Australia ◽  
Organic Phosphorus ◽  
Environmental Parameters ◽  
Strongly Correlated ◽  
Freshwater Lakes ◽  
Nitrogen And Phosphorus ◽  
Water Conductivity ◽  
Blue Green Algae ◽  
Nitrogen Concentrations

The trophic status of three shallow, freshwater lakes on the Swan coastal plain near Perth, Western Australia, was assessed from February 1975 to January 1976. Loch McNess is in a National Park, Lake Joondalup is in an area becoming urbanized, and Lake Monger is in a suburb near the centre of Perth. Monthly measurements were made of phytoplankton numbers and environmental parameters, including forms of nitrogen and phosphorus. Populations tended to be high when lake levels were low. Phytoplankton numbers were dominated by blue-green 'algae' in summer in each lake, with the lowest numbers in Loch McNess. Green algae were most prominent in autumn and winter. Diatoms were present at relatively lower numbers throughout the year. Phytoplankton numbers were strongly correlated with phosphorus levels, particularly for blue-green algae, and less so with nitrogen. Green algae were also strongly correlated with water conductivity. Nearly 80% of variance in phytoplankton numbers was accounted for in multiple linear regression by temperature, sunlight hours, depth, pH, conductivity and phosphate, organic phosphorus, ammonia, nitrate-nitrite, and organic nitrogen concentrations. Much of the variance was accounted for by the nutrients alone. Comparisons with data in the literature suggest that Lakes Joondalup and Monger are eutrophic by world standards, and are far more eutrophic than Loch McNess.

The digestibility and the nitrogen, phosphorus and ash contents of the leaves of some Australian trees and shrubs

1973 ◽  
Vol 13 (62) ◽  
pp. 245 ◽  
Author(s):  
MN McLeod
Keyword(s):  
Significant Variation ◽  
Dry Matter ◽  
Mature Trees ◽  
Lower Range ◽  
Nitrogen Levels ◽  
Dry Matter Digestibility ◽  
Individual Trees ◽  
Trees And Shrubs ◽  
Nitrogen Phosphorus

The dry matter digestibility measured in vitro and the levels of nitrogen, phosphorus and ash were determined on the leaves from mature trees of twenty-one species growing in two arboreta in southeastern Queensland and known to be grazed by animals. Most of the leaf samples had digestibilities in the lower range (68 per cent samples < 50 per cent D.M.D.) and low ash levels (65 per cent samples < 7 per cent ash). Nitrogen levels were satisfactory (86 per cent samples in range 1.5-3.0 per cent N) but the level of phosphorus tended to be low (84 per cent samples < 0.20 per cent P). Statistically significant variation between individual trees and seasons was found with some species.

Sign in / Sign up

Export Citation Format

Share Document