Diel Periodicity of Chlorophyll a Concentration in Oregon Coastal Waters

1972 ◽  
Vol 29 (9) ◽  
pp. 1253-1259 ◽  
Author(s):  
Walter A. Glooschenko ◽  
Herbert Curl Jr. ◽  
Lawrence F. Small
Keyword(s):  
Light Intensity ◽  
Chlorophyll A ◽  
Coastal Waters ◽  
Dark Period ◽  
Skeletonema Costatum ◽  
Time Of Day ◽  
Light Period ◽  
Diel Periodicity ◽  
Low Light ◽  
Chlorophyll Precursor

Concentrations of chlorophyll a in phytoplankton exhibited a diel periodicity in Oregon coastal waters. Maximum surface concentrations often occurred around midnight and highest 25-m concentrations early in the evening (or even in late afternoon). Concentrations at intermediate depths fell in between and in a predictable progression with depth and time of day. Minimum chlorophyll a values occurred in the afternoon. No definite periodicity was established at 50 m.Laboratory studies with Skeletonema costatum demonstrated that the diel cycle of chlorophyll a per cell was related to the light intensity and duration to which cells were exposed. Highest concentrations of this pigment occurred early in the dark period and lowest concentrations in the light period when cells were grown under photoperiods of 9, 12, and 15 hr at a light intensity of approximately 1200 ft-c. Pigment bleaching probably was responsible for the low concentrations during the light period. The decline of chlorophyll a from the maximum early in the dark period began after the cells possibly became deficient in some chlorophyll precursor or energy-yielding substrate. Addition of an external carbon source during the dark period prolonged the high chlorophyll a concentrations in the dark before the decline began. Under low light (400 ft-c) chlorophyll a synthesis occurred only in the light. This phenomenon was most likely due to an insufficient amount of energy-yielding substrate or precursor synthesized during the low-light period, and the lack of bleaching in the light period at this lower intensity. The laboratory results were consistent with interpretations of the field data. A correction for diel pigment periodicity is recommended for models estimating photosynthesis from chlorophyll and light data and for oceanographic surveys during which sampling of chlorophyll a is carried out throughout the 24-hr day.

Diurnal Variation in the Response of the Mandible to Orthopedic Force

2002 ◽  
Vol 81 (10) ◽  
pp. 711-715 ◽  
Author(s):  
S. Yamada ◽  
S. Saeki ◽  
I. Takahashi ◽  
K. Igarashi ◽  
H. Shinoda ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Dark Period ◽  
Time Of Day ◽  
Light Period ◽  
Considerable Reduction ◽  
Cartilage Metabolism ◽  
Differentiation And Proliferation ◽  
And Cartilage

Bone and cartilage metabolism is known to be more active during rest than during periods of activity. The purpose of this study was to examine the hypothesis that mandibular retractive force could be more effective when applied to rats during rest. Mandibular retractive force caused a considerable reduction in the condylar length in experimental groups, and the magnitude of this reduction was greater in the Light-period (08:00-20:00) group than in the Dark-period (20:00-08:00) group. The differentiation and proliferation of chondrocytes were inhibited in animals in the Light-period group, compared with those in the Dark-period group. These results suggest that the orthopedic effects of mandibular retractive force vary depending on the time of day the force is applied, and that such force may be more effective while animals are resting than while they are active.

Carbon to chlorophyll-a ratio in modeling long-term eutrophication phenomena

1998 ◽  
Vol 38 (11) ◽  
pp. 227-235 ◽  
Author(s):  
Haisheng Jin ◽  
Shinji Egashira ◽  
K. W. Chau
Keyword(s):  
Light Intensity ◽  
Chlorophyll A ◽  
Coastal Waters ◽  
Present Method ◽  
Bottom Water ◽  
Specific Growth ◽  
Weighted Average ◽  
Anoxic Condition ◽  
Ambient Conditions

Carbon to chlorophyll-a ratio (CCHL) is formulated based on the assumption that adaptive changes in carbon to chlorophyll occur so as to maximize the specific growth rate for ambient conditions, including solar radiation and water temperature. With the dynamic CCHL, an unsteady two-layered, two-dimensional eutrophication numerical model for density stratified coastal waters has been developed. Saturated light intensity (IS) is determined as weighted average of the light intensity for previous three days to incorporate light acclimation by phytoplankton. The bottom water anoxic condition during summer in Tolo Harbour, Hong Kong is successfully reproduced by the present method. Otherwise, the simulation with a constant CCHL gave a wrong result.

Diel periodicity in spermatophore formation in the house cricket, Acheta domesticus (L.)

1968 ◽  
Vol 46 (4) ◽  
pp. 695-698 ◽  
Author(s):  
J. E. McFarlane
Keyword(s):  
Dark Period ◽  
Continuous Light ◽  
Light Period ◽  
Acheta Domesticus ◽  
Diel Periodicity ◽  
Light Conditions ◽  
House Cricket ◽  
Male House

Male house crickets reared individually at 28 °C developed a diel periodicity in spermatophore formation, which consisted in loss of the spermatophore during the dark period and secretion during the light period. The periodicity became established only after most of the insects had formed at least two spermatophores in a random way with respect to light conditions. When periodicity was established, rearing the insects in continuous light resulted in the retention of the spermatophore by nearly all insects. Stridulation began in all experiments at the time of first spermatophore formation.

Chlorophyll a and c in Cultures of Marine Algae

1963 ◽  
Vol 14 (2) ◽  
pp. 148 ◽  
Author(s):  
GF Humphrey
Keyword(s):  
Light Intensity ◽  
Chlorophyll A ◽  
Growth Phase ◽  
Marine Algae ◽  
Skeletonema Costatum ◽  
Natural Populations ◽  
Initial Growth ◽  
Cell Numbers ◽  
Maximum Cell ◽  
Effect Of Light

Gymnodinium, Nitzschia closterium, and Skeletonema costatum were grown in the presence of bacteria, and N. closterium in the absence of bacteria, for 7 weeks. Each week samples were analysed by the Richards-Thompson method for chlorophyll a and c. Maximum cell numbers were reached in 1-3 weeks. Gymnodinium grew better at 680 f.c. than at 420 f.c. but the reverse was true of Nitzschia and Skeletonema. The chlorophyll content of the Gymnodinium cultures was similar at each light intensity but Nitzschia gave more chlorophyll at 420 f.c. With Skeletonema there was no consistent effect of light. During the initial growth phase, Gymnodinium contained 0.33-0.87 �g chlorophyll a and 0.56-1.88 pg chlorophyll c per million cells. The corresponding figures for Skeletonema were 0.03-0.06 and 0.03-0.08, and for Nitzschia 0.13-1.08 and 0.11-0.87. The ratio of c to a varied from 1.30 to 1.84 for Gymnodinium, 0.69 to 1 .61 for Skeletonema, and 0.44 to 2.21 for Nitzschia. These ratios are all less than the maximum (3.3) found for natural populations of phytoplankton from the Coral and Tasman Seas. There was no evidence in the culture experiments that chlorophyll c breaks down more slowly than a and thus accumulates in old populations.

Characterization of diurnal photosynthetic rhythms in the marine diatom Skeletonema costatum grown in synchronous culture under ambient and elevated CO2

2004 ◽  
Vol 31 (4) ◽  
pp. 399 ◽  
Author(s):  
Xiongwen Chen ◽  
Kunshan Gao
Keyword(s):  
Chlorophyll A ◽  
Elevated Co2 ◽  
Skeletonema Costatum ◽  
Co2 Enrichment ◽  
Light Period ◽  
Marine Diatom ◽  
Initial Slope ◽  
Co2 Uptake ◽  
Chlorophyll A Content ◽  
Ambient Co2

Photosynthetic performance was examined in Skeletonema costatum (Greville) Cleve. under 12 : 12-h light : dark (LD) cycle at ambient CO2 (350 μL L–1) and elevated CO2 (1000 μL L–1). At ambient CO2, the cellular chlorophyll a content, the light-saturated photosynthetic rate (Pm), the initial slope of the light saturation curves (α), the photochemical efficiency of PSII (Fv / Fm), the apparent carboxylating efficiency (ACE) and the photosynthetic affinity for CO2 [1 / Km(CO2)] all showed rhythmical changes with different amplitudes during the light period. The Pm had similar changing pattern in the light period with the ACE and 1 / Km(CO2) rather than with the α and Fv / Fm, indicating that rhythmical changes of photosynthetic capacity may be mainly controlled by the activity of C-reduction associated with CO2 uptake during the light period. The CO2 enrichment reduced the ACE and the affinity to CO2, and increased the α, cellular chlorophyll a content and Pm based on cell number. By contrast, the changing patterns of all photosynthetic parameters examined here during the light period had almost the same for cells grown at ambient CO2 and elevated CO2, suggesting that the photosynthetic rhythms of S. costatum are not affected by CO2 enrichment.

Light Absorption, Fluorescence, and Photosynthesis: Skeletonema Costatum and Field Measurements

Ocean Optics ◽  
1994 ◽  
Author(s):  
Dale A. Kiefer
Keyword(s):  
Environmental Factors ◽  
Light Intensity ◽  
Chlorophyll A ◽  
Light Absorption ◽  
Nutrient Concentration ◽  
Skeletonema Costatum ◽  
Field Measurements ◽  
Fluorescence Of Chlorophyll A ◽  
The Relationship

In this chapter we will consider the fate of photons that are absorbed by phytoplankton. While such interaction will involve both the scattering and absorption of photons, we will be concerned with absorption and the subsequent processes of photosynthesis and the fluorescence of chlorophyll a. In particular and as the title of this chapter indicates, I wish to consider the environmental factors that cause variations in the cellular rates of light absorption, fluorescence, and photosynthesis. This consideration will focus on how environmental factors such as temperature, nutrient concentration, light intensity, and photoperiod effect changes in these three processes. Our approach to examining the relationship between light absorption, fluorescence, and photosynthesis is based upon phenomenological formulations between these three processes.

Circadian Control of Sexual Drive Level in Dacus Tryoni (Diptera: Tephritidae)

Behaviour ◽  
1975 ◽  
Vol 54 (1-2) ◽  
pp. 111-141 ◽  
Author(s):  
Peter H. Tychsen
Keyword(s):  
Light Intensity ◽  
Circadian Clock ◽  
Sexual Behaviour ◽  
Light Stimulus ◽  
Time Of Day ◽  
Drive Level ◽  
Low Light ◽  
Daily Fluctuation ◽  
Sexual Drive ◽  
Low Light Intensity

AbstractThere is a large daily fluctuation in the willingness of both males and females of Dacus tryoni to respond with sexual behaviour to a standard light stimulus. The daily fluctuation in sexual drive level persists under constant low light intensity with a period of about 28 hr so it is timed by a circadian clock. Experiments were carried out on the decline in drive level that occurs after each daily peak. Expression of sexual behaviour plays little or no part in causing this decline but periods of low light intenstiy cause large and long lasting reductions in sexual drive level. A consistent relationship was found between the immediate effect of periods of low light intensity on the drive level and their effect on the subsequent phase of the fluctuation (i.e. their effect on the circadian clock). This suggests that the endogenous clock not only controls the timing of fluctuations in drive level but also determines the level of sexual drive at each time of day.

scholarly journals Respon Karakter Morfo-Fisiologi Genotipe Tomat Senang Naungan Pada Intensitas Cahaya Rendah (The Respon of Morpho-Physiological Characters of Loving-Shade Genotypes at Low Light Intensity)

2019 ◽  
Vol 29 (1) ◽  
pp. 22
Author(s):  
Dwiwanti Sulistyowati ◽  
Muhammad Ahmad Chozin ◽  
Muhammad Syukur ◽  
Maya Melati ◽  
Dwi Guntoro
Keyword(s):  
Light Intensity ◽  
Leaf Area ◽  
Chlorophyll A ◽  
Light Stress ◽  
Leaf Number ◽  
Low Light ◽  
Fruit Number ◽  
Low Light Stress ◽  
Tomato Genotypes ◽  
Physiological Characters

<p>Tomat memiliki potensi untuk dikembangkan dengan sistem pertanaman berganda sebagai tanaman sela di bawah tegakan, baik di kehutanan, perkebunan, maupun pekarangan, sehingga mengalami stres cahaya rendah.  Stres cahaya rendah menyebabkan berbagai perubahan morfologi, anatomi dan fisiologi. Tujuan dari penelitian ini adalah untuk mempelajari karakter morfologi, anatomi dan fisiologi genotipe tomat pada intensitas cahaya rendah. Percobaan dilaksanakan di kebun percobaan Sekolah Tinggi Penyuluhan Pertanian (STPP) Bogor dari bulan Oktober 2014 sampai dengan Januari 2015. Percobaan menggunakan Rancangan Petak Tersarang (<em>nested design</em>) yang diulang tiga kali, faktor pertama terdiri atas dua taraf naungan, tanpa naungan (0%) dan naungan 50%. Faktor kedua berupa 50 genotipe tomat (ditapis menjadi 4 kelompok genotipe, yaitu senang, toleran, moderat dan peka naungan). Hasil penelitian menunjukkan bahwa genotipe tomat senang naungan mampu berproduksi lebih tinggi saat ternaungi, karena genotipe ini mampu beradaptasi lebih baik. Yaitu dengan cara meningkatkan tinggi tanaman, jumlah daun, luas daun, jumlah bunga dan jumlah buah dibandingkan genotipe peka. Terjadi peningkatan klorofil b lebih tinggi daripada klorofil a, sehingga terjadi penurunan yang lebih tinggi pada rasio klorofil a/b. Karakter yang berkorelasi dan berpengaruh langsung terhadap produksi tomat pada naungan 50% adalah luas daun, jumlah bunga, umur panen, rasio klorofil a/b, jumlah buah dan bobot per buah.</p><p><strong>Keywords</strong></p><p><strong></strong>Intensitas cahaya rendah; Karakter genotipe tomat</p><p><strong>ABSTRACT</strong></p><p>Tomatoes have the potential to be developed with multiple cropping systems as intercropping plants under stands, both in forestry, plantations, and yard, thus experiencing low light stress. Low light stress causes a variety of morphological, anatomical and physiological changes. The aim of this study was to investigate the morphological, anatomical and physiological characters of tomato genotypes at low light intensity. The experiments were conducted in the experimental field of Bogor Agricultural Extension Institute, in Bogor, from October 2014 to January 2015. The experiment was arranged in nested randomized design with two factors and three replication. The first factor consisted of two levels of shading intensity, i.e. without shade (0 %) and 50% shading. and the second factor was 50 tomato genotypes (4 groups of tomato genotypes, i.e. shade-loving, shade-tolerant, shade-moderate and shade-sensitive genotypes). The results showed that the shade-loving genotypes was capable of producing higher levels when shaded, as the genotype was able to adapt better. That was by increasing the plant height, leaf number, leaf area, flower number and fruit number compared to sensitive genotypes. Increased chlorophyll b is higher than chlorophyll a, resulting in a higher decrease in the ratio of chlorophyll a/b. Character that correlates and directly affects tomato production in 50% shade was leaf area, leaf number, harvesting time, a/b chlorophyll ratio, fruit number and fruit weight.</p>

EVOLUTION OF CARBON DIOXIDE BY TOBACCO LEAVES DURING THE DARK PERIOD FOLLOWING ILLUMINATION WITH LIGHT OF DIFFERENT INTENSITIES

1961 ◽  
Vol 39 (5) ◽  
pp. 1045-1056 ◽  
Author(s):  
E. B. Tregunna ◽  
G. Krotkov ◽  
C. D. Nelson
Keyword(s):  
Carbon Dioxide ◽  
Light Intensity ◽  
Short Duration ◽  
Dark Period ◽  
Light Period ◽  
Closed Circuit ◽  
Carbon Dioxide Evolution ◽  
Tobacco Leaves

Detached tobacco leaves were placed in a closed-circuit apparatus and the air was continuously circulated over the leaves and through an infrared CO2 analyzer. From the known volume of the apparatus and the percentage of carbon dioxide in its air, the amounts of carbon dioxide either absorbed or evolved by a leaf were calculated.When, after a period of illumination, leaves were darkened, the attainment of their steady rates of respiration was preceded by two outbursts of carbon dioxide evolution. Since these outbursts occurred only after a period of illumination, it has been concluded that both were the result of photostimulation. The peak of the first outburst was usually considerably higher than that of the second. It was of short duration and the height of its peak was accentuated by the increased light intensity in the preceding light period. The second outburst lasted longer and prior light intensity had no effect on the height of its peak.

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