Effect of Changes in Zooplankton on Orthophosphate Dynamics of Natural Phytoplankton Communities

1987 ◽  
Vol 44 (1) ◽  
pp. 176-182 ◽  
Author(s):  
Edward McCauley ◽  
Jacob Kalff
Keyword(s):  
Large Volume ◽  
Algal Biomass ◽  
Field Experiments ◽  
Phosphorus Uptake ◽  
Zooplankton Biomass ◽  
Crustacean Zooplankton ◽  
Algal Communities ◽  
Phytoplankton Communities ◽  
Different Levels ◽  
Natural Phytoplankton

Replicate algal communities were isolated from Lake Memphremagog (Quebec–Vermont) in large–volume enclosures, and the abundance of herbivores was changed in them to produce a gradient of herbivore biomass among enclosures. The performance of the phytoplankton and their phosphorus uptake was observed in response to these different levels of crustacean Zooplankton biomass. In general, reducing Zooplankton biomass did not lead to phosphorus-deficient algal communities. Seven field experiments were done in 1979, 1980, and 1981 Only two of these experiments produced algal communities in which the cycling rate of orthophosphate per unit algal biomass was modified by reduction of crustacean Zooplankton biomass.

THE EFFECTS OF OIL AND CHEMICALLY DISPERSED OIL ON NATURAL PHYTOPLANKTON COMMUNITIES

1987 ◽  
Vol 1987 (1) ◽  
pp. 255-257 ◽  
Author(s):  
M. Scholten ◽  
J. Kuiper
Keyword(s):  
Oil Spill ◽  
Primary Productivity ◽  
Algal Biomass ◽  
Crude Oils ◽  
Rapid Succession ◽  
Dispersed Oil ◽  
Phytoplankton Communities ◽  
Chemically Dispersed Oil ◽  
Natural Phytoplankton

ABSTRACT The effects of various crude oils and chemically dispersed oil on natural phytoplankton communities were tested in several experiments using marine mesocosms. Elevated algal biomass concentrations were found in most of the experiments, despite the long-term inhibition of primary productivity per unit chlorophyll. This result is due to reduced grazing upon algae as a consequence of oil-induced mortality of copepods or bivalves. A rapid succession from a diatom-dominated algae community to one dominated by microflagellates can be observed after an oil spill, owing to the more rapid exhaustion of silicate. If silicate is not being exhausted, a prolonged abundance of diatoms is observed. Treatment of oil with dispersant generally will aggravate effects, because of high dissolved oil concentrations in the water.

Photoacclimation of natural phytoplankton communities

2016 ◽  
Vol 542 ◽  
pp. 51-62 ◽  
Author(s):  
JR Graff ◽  
TK Westberry ◽  
AJ Milligan ◽  
MB Brown ◽  
G Dall’Olmo ◽  
...  
Keyword(s):  
Phytoplankton Communities ◽  
Natural Phytoplankton

scholarly journals Effects of disk tillage on soil condition, crop yield and weed infestation

2011 ◽  
Vol 48 (No. 1) ◽  
pp. 20-26
Author(s):  
M. Birkás ◽  
T. Szalai ◽  
C. Gyuricza ◽  
M. Gecse ◽  
K. Bordás
Keyword(s):  
Winter Wheat ◽  
Crop Yield ◽  
Field Experiments ◽  
Soil Layer ◽  
Soil Condition ◽  
Perennial Weeds ◽  
Weed Infestation ◽  
Set Up ◽  
Different Levels

This research was instigated by the fact that during the last decade annually repeated shallow disk tillage on the same field became frequent practice in Hungary. In order to study the changes of soil condition associated with disk tillage and to assess it is consequences, long-term tillage field experiments with different levels of nutrients were set up in 1991 (A) and in 1994 (B) on Chromic Luvisol at Gödöllö. The effects of disk tillage (D) and disk tillage combined with loosening (LD) on soil condition, on yield of maize and winter wheat, and on weed infestation were examined. The evaluation of soil condition measured by cone index and bulk density indicated that use of disking annually resulted in a dense soil layer below the disking depth (diskpan-compaction). It was found, that soil condition deteriorated by diskpan-compaction decreased the yield of maize significantly by 20 and 42% (w/w), and that of wheat by 13 and 15% (w/w) when compared to soils with no diskpan-compaction. Averaged over seven years, and three fertilizer levels, the cover % of the total, grass and perennial weeds on loosened soils were 73, 69 and 65% of soils contained diskpan-compaction.

Differences between Nearshore and Offshore Phytoplankton Communities in Lake Ontario

1987 ◽  
Vol 44 (12) ◽  
pp. 2155-2163 ◽  
Author(s):  
I. M. Gray
Keyword(s):  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
Algal Biomass ◽  
Phytoplankton Community ◽  
Seasonal Pattern ◽  
Principal Component ◽  
Lake Ontario ◽  
Dominant Group ◽  
Phytoplankton Communities ◽  
Eutrophic Species

Differences between nearshore and offshore phytoplankton biomass and composition were evident in Lake Ontario in 1982. Phytoplankton biomass was characterized by multiple peaks which ranged over three orders of magnitude. Perhaps as a consequence of the three times higher current velocities at the northshore station, phytoplankton biomass ranged from 0.09 to 9.00 g∙m−3 compared with 0.10 to 2.40 g∙m−3 for the midlake station. Bacillariophyceae was the dominant group at the northshore station until September when Cyanophyta contributed most to the biomass (83%). Although Bacillariophyceae was the principal component of the spring phytoplankton community at the midlake station, phytoflagellates (49%) and Chlorophyceae (25%) were responsible for summer biomass, with the Chlorophyceae expanding to 80% in the fall. The seasonal pattern of epilimnetic chlorophyll a correlated with temperature. While chlorophyll a concentrations were similar to values from 1970 and 1972, algal biomass had declined and a number of eutrophic species (Melosira binderana, Stephanodiscus tenuis, S. hantzschii var. pusilla, and S. alpinus) previously found were absent in 1982.

scholarly journals PHOSPHORUS NUTRITION OF SOYBEANS AS AFFECTED BY PLACEMENT OF FERTILIZER PHOSPHORUS

1983 ◽  
Vol 63 (2) ◽  
pp. 199-210 ◽  
Author(s):  
C. W. BULLEN ◽  
R. J. SOPER ◽  
L. D. BAILEY
Keyword(s):  
Glycine Max ◽  
Total Phosphorus ◽  
Dry Matter ◽  
Field Experiments ◽  
Seedling Emergence ◽  
Phosphorus Uptake ◽  
Growth Chamber ◽  
Grain Yields ◽  
Chamber Experiment ◽  
Glycine Max L

Growth chamber and field experiments were conducted on Southern Manitoba soils, low in available soil phosphorus, to investigate the effects of various placement methods and levels of phosphorus fertilizer on soybean (Glycine max (L.) Merrill ’Maple Presto’). It was found that soybean responded well to applied phosphorus on low-P soil in growth chamber studies. In the first growth chamber experiment, P was applied in solution to 100%, 50%, 25%, 12.5% and 1% of the total soil volume. Dry matter yields, total phosphorus uptake and utilization of fertilizer P increased at each level of applied P as the size of the phosphated band was decreased. The results were partly attributed to greater chemical availability of P in the smaller zones of P fertilizer reaction. In a second growth chamber experiment, soybeans responded differently to phosphorus banded in six different locations. Placement of the fertilizer 2.5 cm directly below the seed was more effective in increasing dry matter yield, total phosphorus uptake and fertilizer P utilization than placement 2.5 cm and 5 cm away at the same depth or placement 5 cm below the seed, whether the band was directly below, 2.5 cm away or 5 cm away. Soybean yield responses in the field were greatest with P banded 2.5 cm directly below the seed on low-P soils. Placement of P 2.5 cm below the seed resulted in grain yields that were 64% and 50% higher (at the two sites) than those obtained in control plots. Sidebanding P, 2.5 cm below and 2.5 cm away from the seed at the same level of application, improved grain yields of control plots by 40% and 39%. Seed placement and broadcast applications of P were not as effective in increasing grain yields. Broadcasting P in fall or in spring at rates of up to 52.38 kg P/ha did not result in significantly higher grain yields than those obtained in control plots. Placement of P in contact with the seed appeared to reduce seedling emergence, resulting in depressed yields when 52.38 kg P/ha were applied. Key words: Glycine max L. Merrill, ’Maple Presto’

scholarly journals Feeding patterns in Eubranchipus grubii (Dybowski 1860) (Branchiopoda: Anostraca) and its potential influence on the phytoplankton communities of vernal pools

2018 ◽  
Vol 77 (2) ◽  
Author(s):  
Sofia Celewicz ◽  
Michał Jan Czyż ◽  
Bartłomiej Gołdyn
Keyword(s):  
Cell Volume ◽  
Phytoplankton Community ◽  
Grazing Pressure ◽  
Potential Influence ◽  
Filter Feeder ◽  
Algal Communities ◽  
Phytoplankton Communities ◽  
Fairy Shrimps ◽  
The Mean ◽  
And Control

Filtration patterns in the fairy shrimp Eubranchipus grubii were analysed under laboratory conditions using water containing phytoplankton from their actual locality in western Poland. After 48 hours of feeding, we compared the structure of algal communities in water samples in treatments with males, females and control. The mean filtration rate for E. grubii was relatively high (14,488 mL h-1) in comparison to other crustacean filter feeders and was higher for females than for males. Fairy shrimps grazed effectively on all 11 dominant phytoplankton taxa and there was no sign of overall preferences with regard to taxon, cell volume, length or shape. Female fairy shrimps removed significantly more cells of three taxa (Cryptomonas erosa, C. ovata and Trachelomonas volvocina). The differences between sexes did not depend on the cell volume or length of particular phytoplankton taxa but were significantly related to their initial abundance, initial biomass and shape. The higher the abundance and biomass of the algal taxa, the more intensively it was grazed by females than by males. Females were also observed to graze more on spherical and elongated cells. In conclusion, our results show E. grubii to be an effective, generalist filter feeder capable of significantly influencing the phytoplankton community of a vernal pool. Possible implications of such grazing pressure are also discussed.

Correction of manganese deficiency in barley crops on calcareous soils. 2. Comparison of mixed and compound fertilizers

1973 ◽  
Vol 13 (63) ◽  
pp. 440 ◽  
Author(s):  
DJ Reuter ◽  
TG Heard ◽  
AM Alston
Keyword(s):  
Particle Size ◽  
Field Experiments ◽  
Phosphorus Uptake ◽  
Calcareous Soils ◽  
Nutrient Content ◽  
Manganese Deficiency ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Foliar Sprays ◽  
Compound Fertilizer

Mixed and compound fertilizers made from superphosphate and manganous sulphate were compared in field experiments as sources of manganese for barley on the calcareous soils of southern Yorke Peninsula, South Australia. The compound fertilizers were made by blending manganous sulphate with 'den-fresh' superphosphate before the granulation process: mixed fertilizers were made by mixing the components after manufacture. The fertilizers were applied at sowing at rates of 19 kg haw1P and 16 kg haelMn in one experiment and 28 kg ha-1 P and 6 kg ha-1 Mn in a second experiment. In the latter, up to three foliar sprays of manganous sulphate (1.3 kg ha-1 Mn per spray) were applied in addition. The rate at which the fertilizers reacted with the soil was studied in an incubation experiment, and the nutrient content of particle-size fractions of the fertilizers was also determined. Plant dry weight, manganese and phosphorus uptake, and grain yield were increased to a greater extent by application of the compound fertilizer than by the mixed fertilizer. Application of compound fertilizers at sowing also delayed the appearance of manganese deficiency symptoms in crops by two weeks compared with mixed fertilizers. Neither fertilizer prevented the occurrence of manganese deficiency and further yield increases were obtained by subsequent foliar sprays of manganous sulphate. Fertilizer manganese was rapidly immobilized in the soil. After 167 hours' incubation, approximately three quarters of that added in manganous sulphate, and in the mixed and compound fertilizers was not extractable in divalent form. The variation in nutrient content of particle size fractions of a compound fertilizer was much less than that in a mixed fertilizer.

scholarly journals Contribution of tidal submergence to phosphorus nutrition and yield of rice

1970 ◽  
Vol 8 (2) ◽  
pp. 207-212
Author(s):  
MA Haque
Keyword(s):  
Ground Water ◽  
Field Experiments ◽  
Phosphorus Uptake ◽  
Growth Yield ◽  
Water Source ◽  
Phosphorus Nutrition ◽  
Rice Grain ◽  
Rice Varieties ◽  
Traditional Variety ◽  
Tidal Water

Two pot and two field experiments were conducted at Patuakhali Science and Technology University research farm to investigate the contribution of tidal submergence to phosphorus nutrition and yield of rice. Pot and field experiments were conducted in the Aus and Aman seasons of 2009, respectively. The factorial experiments include two levels of water source- i) tidal water and ii) ground water, and three levels of fertilizers- i) absolute control (no fertilizer), ii) NK (P omission) and iii) NPK (P addition). The rice varieties used were BRRI dhan27 (HYV) and Local Mala (Traditional variety) in Aus season and BR23 (HYV) and Lalmota (Traditional variety) in Aman season. A general increase in growth, yield and yield contributing parameters were found due to irrigation with tidal water. Tidal water contributed about 21 (BR23) and 7 (Lalmota) % higher grain yield in Aman season 2009 and about 2 g biomass yield per pot (both BRRI dhan27 and Local Mala) in Aus season of 2009 compared to ground water. Phosphorus content of rice grain and straw was always higher when plants are irrigated with tidal water. In general tidal submergence increases P uptake of rice. Phosphorus uptake from tidal water treatments increased when plants were supplied with N and K fertilizer. Tidal submergence contributed about 5-6 kg P/ha in P omission plot, and about 12-14 kg P/ha in plots with added P.  Keywords: Phosphorus; Rice; Tidal submergence DOI: 10.3329/jbau.v8i2.7927 J. Bangladesh Agril. Univ. 8(2): 207-212 2010

scholarly journals Canopy structure and its relationship with yield and synchrony in pod maturity of mungbean (Vigna rediata L.)

2020 ◽  
Vol 49 (2) ◽  
pp. 329-334
Author(s):  
MMA Mondal
Keyword(s):  
Seed Yield ◽  
Field Experiments ◽  
Unit Area ◽  
Canopy Structure ◽  
Plant Population ◽  
Plant Spacing ◽  
Tropical Condition ◽  
Canopy Area ◽  
Different Levels ◽  
Plant Control

Field experiments were conducted under sub-tropical condition during March-May of two consecutive years of 2013 and 2014 to assess the effect of different levels of debranching and spacing on synchronous pod ripening and yield of mungbean. The debranching levels were: (i) Category 1 [main stem (MS) with 4 branches per plant, control], (ii) category 2 (MS with three branches per plant), (iii) category 3 (MS with two branches per plant), (iv) category 4 (MS with one branch per plant) and (v) category 5 (only MS). Under recommended plant spacing (30 cm × 10 cm), plants having MS with 3 branches produced the highest seed yield due to increased number of seeds per pod over category 1. The lowest seed yield was recorded in category 5 (only MS plant) due to fewer number of pods per plant. When the optimum plant population per unit area according to canopy area was considered, it was estimated that the highest plants/m2 was accommodated in MS only of 50 plants/m2 showing the highest seed yield (2570 kg/ha) followed by MS with one branch (40 plants/m2, 2460 kg/ha) and these two treatments also showed synchronous pod maturity. The lowest plant population per unit area was accommodated in MS with 3 and 4 branches (25 plants/m2) and also showed lower seed yield (1910 and 1940 kg/ha, respectively) behaving asynchronous pod maturity.

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