Light Intensity Conditions Research Articles

Inherent rate constants and humidity impact factors of anatase TiO2 film in photocatalytic removal of formaldehyde from air

In photocatalytic oxidation (PCO) of volatile organic compounds (VOCs), even if using the same UV lamp, reaction rate constant of a photocatalyst denoted as k(I,H)Lamp is still affected by operation conditions of light intensity (I) and humidity. It is of great significance to find characteristic parameters of photocatalysts, which excludes the effect of above-mentioned operation conditions and enables direct comparisons of photocatalysts. For this purpose, PCO of formaldehyde in synthetic air in a continuous-flow reactor over transparent films of anatase TiO2 was investigated using three commercially available UV lamps, i.e. UVC, UVA black (UVA1) and UVA white (UVA2). Thereby, inherent rate constant (kLamp) that is only related to the wavelength of UV lamp but independent of light intensity and humidity was found. It suggested that a sequence of kLamp under the three UV lamps, kUVC>>kUVA1∼kUVA2, which, for instance, are 1.6, 0.33 and 0.26cm2s−1mW−1 at low light intensity, respectively. Moreover, humidity impact factor (fH) is approximately 3, 0 and −0.4 in three regimes of low, medium and high humidity (LH, MH, and HH), respectively, which manifests positive, zero-sum and negative effects of humidity on the PCO reaction rate. The zero-sum effect of humidity in the MH regime was observed for the first time. Finally, a generalized and quantitative relationship to express k(I,H)Lamp as a function of I and humidity was built.

Interacting effects of high light and elevated CO2 on the nutraceutical quality of two differently pigmented Lactuca sativa cultivars (Blonde of Paris Batavia and Oak Leaf)

This study presents changes in the nutraceutical quality and biomass production of two differently pigmented Lactuca sativa (L.) cultivars grown under various combinations of high light (700μmolphotonsm−2s−1) and elevated CO2 (700μmolmol−1) conditions. In an ambient CO2 atmosphere, high light intensity increased biomass production in the green cultivar (Blonde of Paris Batavia) but not in the red cultivar (Oak Leaf). In both cultivars, high light intensity increased the concentration of soluble proteins and sugars. High light intensities also increased the levels of carotenoids, glutathione, total phenols and anthocyanins, which was most likely due to oxidative stress. Conversely, the levels of almost all minerals remained unchanged compared with the values detected for control light intensity and ambient CO2 conditions. When a high light intensity was applied at elevated CO2 conditions, the biomass production increased in both cultivars. The concentrations of minerals (except Fe and Mg), glutathione and ascorbate remained constant compared with the high light and ambient CO2 conditions, which indicated that these components and biomass accumulated at comparable rates. The decreases in the levels of Chl-a, carotenoids, total phenols and anthocyanins in response to elevated CO2 levels at high light conditions could indicate a relief of oxidative stress due to an improved balance between ATP and NADPH production and consumption at elevated CO2 levels. These results demonstrate that the biomass production and the nutritional quality of lettuce can be improved, but the response is cultivar-specific, and the choice of the best cultivation practice (using high light intensity alone or in combination with elevated CO2 levels) depends on the attributes that are targeted for improvement.

Dynamics of potentially harmful phytoplankton in a semi-enclosed bay in the Sea of Oman

The dynamics of potentially harmful phytoplankton in relation to environmental parameters was investigated in the semi-enclosed Bay of Bandar Khayran (Sea of Oman) from April 2006 through April 2011. In total, 24 potentially harmful algal species were identified, including 11 species of dinoflagellates and eight species of diatoms. The dinoflagellates Prorocentrum minimum (Pavillard) Schiller, 1933, Scrippsiella trochoidea Balech ex Loeblich III, 1965, and Noctiluca scintillans (Macartney) Kofoid and Swezy, 1921 were most abundant during the Southwest Monsoon (SWM, July-September) and Northeast Monsoon (NEM, January-March) seasons, while other species occurred in low abundance and with no clear seasonal patterns. A dense bloom of Cochlodinium polykrikoides Margalef, 1961 that affected the distribution and abundance of other harmful algal species (HAB) was observed for the first time in the Sea of Oman during 2008-2009. Prorocentrum minimum increased in abundance during and after the decay of the Cochlodinium bloom while S. trochoidea was suppressed during this bloom, increasing thereafter once again. Noctiluca scintillans disappeared in the late SWM and NEM of 2008 and SWM of 2009, when blooms typically occur annually. Prorocentrum minimum and S. trochoidea persisted throughout the annual cycle of all years, enhancing their capability to bloom in the region under favorable conditions of high light intensities and relatively warm waters of low turbulence.

Irreversible collective migration of cyanobacteria in eutrophic conditions.

In response to natural or anthropocentric pollutions coupled to global climate changes, microorganisms from aquatic environments can suddenly accumulate on water surface. These dense suspensions, known as blooms, are harmful to ecosystems and signicantly degrade the quality of water resources. In order to determine the physico-chemical parameters involved in their formation and quantitatively predict their appearance, we successfully reproduced irreversible cyanobacterial blooms in vitro. By combining chemical, biochemical and hydrodynamic evidences, we identify a mechanism, unrelated to the presence of internal gas vesicles, allowing the sudden collective upward migration in test tubes of several cyanobacterial strains (Microcystis aeruginosa PCC 7005, Microcystis aeruginosa PCC 7806 and Synechocystis sp. PCC 6803). The final state consists in a foamy layer of biomass at the air-liquid interface, in which micro-organisms remain alive for weeks, the medium lying below being almost completely depleted of cyanobacteria. These "laboratory blooms" start with the aggregation of cells at high ionic force in cyanobacterial strains that produce anionic extracellular polymeric substances (EPS). Under appropriate conditions of nutrients and light intensity, the high photosynthetic activity within cell clusters leads the dissolved oxygen (DO) to supersaturate and to nucleate into bubbles. Trapped within the EPS, these bubbles grow until their buoyancy pulls the biomass towards the free surface. By investigating a wide range of spatially homogeneous environmental conditions (illumination, salinity, cell and nutrient concentration) we identify species-dependent thresholds and timescales for bloom formation. We conclude on the relevance of such results for cyanobacterial bloom formation in the environment and we propose an ecient method for biomass harvesting in bioreactors.

Effect of light intensity and pH condition on the growth, biomass and lipid content of microalgae Scenedesmus species

The physiological factors for microalgae cultivation are the preliminary steps to overcome the potential biomass demand. In this regard, the influence of light intensity (at six levels: 27, 40.5, 54, 67.5, 81 and 94.5 µmol m−2s−1) and pH conditions (5.0, 6.0, 7.0, 8.0 and 9.0) on the growth and lipid production of Scenedesmus species ADIITEC-II and GUBIOTJT116 was compared in the batch culture. Among the studied species, maximum specific growth (0.334 ± 0.002 day−1) and highest biomass yield (0.41 ± 0.021 g L−1) was achieved for Scenedesmus species ADIITEC-II at light intensity 81 µmol m−2s−1. Similarly, Scenedesmus species GUBIOTJT116 showed increased growth and biomass production at 81 µmol m−2s−1. However, illumination under 94.5 µmol m−2s−1 showed higher lipid production (0.533 ± 0.001 g L−1 and 0.551 ± 0.001 g L−1) for Scenedesmus sp. ADIITEC-II and GUBIOTJT116, respectively. The significant variation in effective pH tolerance, growth and biomass production was observed in the studied pH range. The result obtained in this study provides a potential insight of the strains and could be further explored to improve the biomass and lipid yield.

Novel resistance mechanism of barley chlorina f104 antenna mutant against photoinhibition: possible role of new identified chloroplastic cpNrp protein

Protein with NmrA domain serving as the receptor for oxidized NAD(+)/NADP was identified in chloroplasts of spring barley mutant chlorina f104. NmrA was upregulated under environmental stresses in comparison to wild type plants. Following bioinformatic analysis revealed the nuclear localization signal in this protein. Pathways for the protein transport from cytoplasm into the chloroplast are described, but the mechanism of protein transport from chloroplast to nucleus, where the gene transcription can be possibly affected, is not clear. This protein named as cpNrp (chloroplastic NmrA related protein) is probably a member of new protein family and can serve as chloroplastic redox receptor. Consequently, cpNrp transported as a signal molecule into the nucleus and influences on the gene transcription under environmental stresses (high light radiation). It can be suggested that the presence of these proteins in chloroplasts of chlorina f104 barley mutant is related to up-regulation of photoprotective mechanisms, contributing to maintenance of high resistance against photooxidative damage in conditions of excessive light intensity.

Photoperiod and shading regulate coloration and anthocyanin accumulation in the leaves of malus crabapples

In many ornamental plants, anthocyanin accumulation in leaves is a critical determinant of foliage coloration. However, the mechanism by which photoperiod and shading affect coloration and anthocyanin accumulation in the leaves of woody plants is less clear. By examining the leaves and calli of crabapple (Malus spp.) cultivars with different leaf color characteristics, we analyzed the foliage coloration, flavonoid contents, and expression levels of anthocyanin biosynthetic genes and the McMYB10 transcription factor under different photoperiods and shading treatments. The red color parameters, flavonoid contents, and expression levels of some anthocyanin-related genes in both the leaf and callus were generally higher under sun-exposure or long-day treatments compared to shading or short-day treatments. These data indicate that red color formation in cultivars with leaves that are naturally red requires a suitable photoperiod and light intensity; high light intensity or long-day conditions activate anthocyanin biosynthesis-related genes, leading to anthocyanin accumulation. Our results also indicate that the regulation of anthocyanin biosynthetic metabolism in response to light conditions differs between red-leafed and green-leafed cultivars. Taken together, our data reveal that photoperiod and light intensity are important in the regulation of pigmentation and anthocyanin accumulation in crabapple leaves and calli. Moreover, we provide a useful approach for studying and inducing the production of flavonoids by crabapple callus culture under certain photoperiods.

Low pH Modulates the Macroorganization and Thermal Stability of PSII Supercomplexes in Grana Membranes

Protonation of the lumen-exposed residues of some photosynthetic complexes in the grana membranes occurs under conditions of high light intensity and triggers a major photoprotection mechanism known as energy dependent nonphotochemical quenching. We have studied the role of protonation in the structural reorganization and thermal stability of isolated grana membranes. The macroorganization of granal membrane fragments in protonated and partly deprotonated state has been mapped by means of atomic force microscopy. The protonation of the photosynthetic complexes has been found to induce large-scale structural remodeling of grana membranes—formation of extensive domains of the major light-harvesting complex of photosystem II and clustering of trimmed photosystem II supercomplexes, thinning of the membrane, and reduction of its size. These events are accompanied by pronounced thermal destabilization of the photosynthetic complexes, as evidenced by circular dichroism spectroscopy and differential scanning calorimetry. Our data reveal a detailed nanoscopic picture of the initial steps of nonphotochemical quenching.

Attenuating Photostress and Glare Disability in Pseudophakic Patients through the Addition of a Short-Wave Absorbing Filter.

To evaluate the effects of filtering short wavelength light on visual performance under intense light conditions among pseudophakic patients previously implanted with a clear intraocular lens (IOL). This was a patient-masked, randomized crossover study conducted at 6 clinical sites in the United States between September 2013 and January 2014. One hundred fifty-four bilaterally pseudophakic patients were recruited. Photostress recovery time and glare disability thresholds were measured with clip-on blue-light-filtering and placebo (clear; no blue-light filtration) glasses worn over patients' habitual correction. Photostress recovery time was quantified as the time necessary to regain sight of a grating target after intense light exposure. Glare disability threshold was assessed as the intensity of a white-light annulus necessary to obscure a central target. The order of filter used and test eye were randomized across patients. Photostress recovery time and glare disability thresholds were significantly improved (both P < 0.0001) when patients used blue-light-filtering glasses compared with clear, nonfiltering glasses. Compared with a nonfiltering placebo, adding a clip-on blue-absorbing filter to the glasses of pseudophakic patients implanted with clear IOLs significantly increased their ability to cope with glare and to recover normal viewing after an intensive photostress. This result implies that IOL designs with blue-light-filtering characteristics may be beneficial under intense light conditions.

Stability-Indicating Photochemical Method for the Assay of Riboflavin: Lumichrome Method

A stability-indicating photochemical method for the assay of riboflavin (RF) in photodegraded samples and aged vitamin preparations has been developed. It is based on photochemical conversion of RF to lumichrome (LC) in alkaline solution under controlled conditions of light intensity, temperature, pH, time of exposure, and distance. Under these conditions about two-thirds of RF is converted to LC and on the basis of the RF : LC ratio the concentration of RF can be determined in degraded solutions. The method involves the extraction of photolyzed solutions of RF (pH 2.0) with chloroform and determination of LC along with lumiflavin (LF) by a two-component spectrometric method at 356 and 445 nm. The method has been validated and the results of the assay of RF in photodegraded solutions compare well with those of the standard USP fluorimetric method. The recovery of the method is 99–101% and the precision is within 2%. The method is stability-indicating and can be applied to the assay of RF in photodegraded solutions and aged vitamin preparations. The method is specific compared to that of the USP fluorimetric method in which the degraded LC may interfere with the fluorescence emission of RF.

Developing Control Method Based on the Theory of Fuzzy Sets for MPPT in Solar Arrays

In this paper, a new hybrid method is presented by combining the fuzzy logic controller and using boost converter. Presented fuzzy logic controller does precise and fast tracking of maximum power point in different environmental conditions (light and temperature). The modelling of this method will result in obtaining a more accurate response from the system. The characteristics of photovoltaic systems are inherently nonlinear and depending on functions of environmental parameters such as light, ambient temperature, and its attaching charge. Thus, we can receive the maximum power from PV array by choosing appropriate operating point when the amount of light and temperature are constant. By modifications in environmental conditions (light and temperature), the operating point of array will be changed and consequently by using different methods of maximum power point tracking (MPPT). MPPT can be always kept as receiving power amount from array at its maximum value, in other words, it can track maximum power point. There are several ways to track the maximum power. In order to optimizing use of these modules and the growing reduction of tracking costs of solar systems, the use of power processor in order to achieve maximum power point and control method based on Mamdani's fuzzy inference method is presented in this paper. In proposal method, duty cycle switching of power processor attached to a solar module has been controlled in a way to obtain maximum power point of module under various conditions of temperature and light intensity. An important advantage obtained by comparing with previous methods is that the control method independency of module type is used and there is no need for reference signal or any kind of physical information about nature of module. The advantage of fuzzy controllers is in working with imprecise and nonlinear inputs; there is no need of accurate mathematical model and fast convergence and the lowest fluctuations in MPPT.

Percolation of glassy regions during photopolymerization of epoxy acrylate in DMF

• Many reactions in industry are carried out in organic solvents rather than in bulk. • Photo-DSC method is useful to determine the effect of the solvent content on photo-induced polymerization. • An increase in solvent concentration inversely affected the rate of polymerization. • Gel fraction critical exponent ( β ) displayed no variation during photo-gelation with various DMF contents. The gelation of epoxy acrylate (EA) 80% and tripropyleneglycol diacrylate (TPGDA) 20% was studied through the use of photo-differential scanning calorimetric (photo-DSC) technique in the presence of a thioxanthone based initiator. Photo-induced polymerization reactions were performed under identical conditions of temperature, initiator concentration and UV light intensity in various N,N-dimethylformamide (DMF) contents. Photo-DSC technique allowed us to monitor the gelation without disturbing the system mechanically, and to test the universality of the gelation as a function of DMF content. During gelation, it was observed that all conversion curves presented useful sigmoidal behavior which was predicted by employing a percolation model. Observations around the glass transition point, t g , revealed that gel fraction exponent β obeyed the percolation picture. A significant solvent effect on the photopolymerization kinetics of EA/TPGDA was observed with changes in DMF content. DMF is used as solvent, which acts as a diluent and proton donor during photogelation.

Different tolerances to chemical contaminants between unicellular and colonial morph of Microcystis aeruginosa: Excluding the differences among different strains

In order to ascertain the different tolerances to chemical contaminants in one strain of Microcystis with different morphology, unicellular and colonial Microcystis in one strain was obtained from different conditions of light intensity and temperature. The samples were divided into 8 groups including control (no chemical addition), CuSO4, chloromycetin, and linear alkylbenzene sulfonatelas (LAS) treatments. The cell density, cell viability, superoxide dismutase (SOD), and malonaldehyde of Microcystis were analyzed. It was observed that cell density of both unicellular and colonial Microcystis increased from the beginning to day-5 in the control and the CuSO4 treatments. However, the growth of Microcystis was significantly inhibited in the culture with chloromycetin and LAS treatments. Notably, the inhibition rate was significantly high in unicellular Microcystis relative to the colonial Microcystis. The esterase activity in all the treatments decreased dramatically relating to the control. In addition, the esterase activity in colonial Microcystis was significantly higher than that of the unicellular Microcystis in all the treatments. Although there were no significant differences in activities of SOD between the two morphologies in the control treatments, in all the other treatments, significant differences were observed. The results proved that colony formation of Microcystis could be considered as a strategy in response to chemical stress.

Optimization and lipid production enhancement of microalgae culture by efficiently changing the conditions along with the growth-state

Specifically growth-state-based schemes for cultivation optimization of microalgae Chlorella sp. were researched for the lipid enhancement in biodiesel production, compared with common optimization experiments. The optimized conditions of initial cell density, light intensity and aeration flow in common optimization were about 0.45cm−1 (in OD686, i.e. 0.15g/L), 6000lux and 0.2vvm (mLmL−1min−1) respectively, taking into account the lipid yield and energy consumption. The maximum dry weight and lipid content were 1.2g/L and 33.6% respectively. Then three specific schemes for cultivation conditions adjustment were conducted to study the effects of changing conditions along with growth state for the potential enhancement of biomass and lipid production. The results showed that excellent enhancement of both biomass dry weight of 1.9g/L and lipid yield of 0.6g/L was achieved. The new and specific cultivation method significantly improved the biomass and lipid production by 52.7% and 64.7% respectively, compared with the aforementioned three common optimization experiments. The GC–MS analysis indicated that C16–C18 components accounted for more than 90% of fatty acid, and the fatty acid had better properties than that in common cultivation.

Effect of Light Intensity and Temperature on Growth and Quality Parameters of Grafted Vines

Light and temperature are the most important environmental conditions that impact the growth and quality of grafted vines. In this research, the most suitable light and temperature conditions were tested to determine the best environment for grafted vines grown in pots. This study was conducted to determine the influence of different growth conditions, such as open field, shaded greenhouse and unshaded greenhouse, on grafted vine growth and quality. The length and diameter of shoot, trunk diameter, mean and total leaf area, total soluble sugars, starch and total carbohydrate contents of ‘Narince’ and ‘Trakya Ilkeren’ vines, grafted on 5C rootstock, were investigated in this study. Shaded conditions yielded significantly higher shoot lengths, mean and total leaf areas than other conditions (p&lt;0.05). Among the growth parameters, the highest correlation (r = 0.819) was observed between shoot length and plant total leaf area (p&lt;0.01). The total soluble sugars, starch and total carbohydrates content of vines under shaded and unshaded conditions were higher (p&lt;0.05) than those under open field conditions. Grafted vines had the highest carbohydrate content in unshaded conditions. Under different light intensity, temperature and relative humidity conditions studied, the better results were obtained in the case of unshaded conditions.

Effect of Light Intensity and Temperature on Growth and Quality Parameters of Grafted Vines

Light and temperature are the most important environmental conditions that impact the growth and quality of grafted vines. In this research, the most suitable light and temperature conditions were tested to determine the best environment for grafted vines grown in pots. This study was conducted to determine the influence of different growth conditions, such as open field, shaded greenhouse and unshaded greenhouse, on grafted vine growth and quality. The length and diameter of shoot, trunk diameter, mean and total leaf area, total soluble sugars, starch and total carbohydrate contents of ‘Narince’ and ‘Trakya Ilkeren’ vines, grafted on 5C rootstock, were investigated in this study. Shaded conditions yielded significantly higher shoot lengths, mean and total leaf areas than other conditions (p&lt;0.05). Among the growth parameters, the highest correlation (r = 0.819) was observed between shoot length and plant total leaf area (p&lt;0.01). The total soluble sugars, starch and total carbohydrates content of vines under shaded and unshaded conditions were higher (p&lt;0.05) than those under open field conditions. Grafted vines had the highest carbohydrate content in unshaded conditions. Under different light intensity, temperature and relative humidity conditions studied, the better results were obtained in the case of unshaded conditions.

Year-round Greenhouse Production of Cut Sunflowers in the Rocky Mountain West

The objective of this study was to determine the potential for year-round greenhouse production of specialty cut sunflowers (Helianthus annuus) in Wyoming. Over a 14-month period, we produced cut sunflowers in a nontraditional, transplant-based, potted method using natural light intensity and daylength conditions in Laramie, WY. Three cultivars of annual sunflowers, Dafna, ProCut Bicolor, and Sunbright Supreme, were grown from seeds sown at 2-week intervals starting on 16 Nov. 2011. Each planting consisted of four replications of four plants each. Seedlings were transplanted into 550-mL square plastic pots 15 days after sowing and were placed on greenhouse benches in blocks according to sow date. Flowers were cut at soil level when ray florets opened. Data collected included days to harvest and stem length for each stem. Results indicated significant cultivar by sow date interactions for days to harvest and stem lengths, indicating the importance of cultivar selection. Mean days to harvest ranged from 57 days (‘Sunbright Supreme’) to 103 days (‘ProCut Bicolor’). Mean stem lengths ranged from 43 cm (‘Dafna’) to 153 cm (‘Sunbright Supreme’). Overall, the results of this study show potential for year-round production of cut sunflowers and can help guide producers in the Rocky Mountain west to choose cultivars that best fit the needs of their business and market demand.

Validation of a two-dimensional modeling of an externally irradiated slurry photoreactor

A two-dimensional model describing the behavior of a batch cylindrical photoreactor has been validated through a series of photocatalytic reactivity runs. The light intensity radiation field produced by 1–6 external UV fluorescent lamps was modeled together with Langmuir–Hinshelwood kinetics and 4-nitrophenol (NP) and Degussa P25 TiO2 were used as the probe molecule and the catalyst, respectively. The experiments were carried out under different conditions of light intensity, photocatalyst amount and substrate concentration. The model parameters were the kinetic constant of substrate adsorption, desorption and degradation and the exponent of the power law expressing the kinetics dependence on the light intensity. A least-squares best fitting procedure was used to fit the experimental data to the model and find the four required parameters. A satisfactory agreement was obtained between experimental and calculated values of the observed pseudo-first order kinetic constant, with a coefficient of determination R2=0.83. Notably, the present model is of general interest for cylindrical slurry photoreactors, where different molecules can be oxidized in the presence of several photocatalysts and it can be used, for instance, to accurately compare the performance of a set of catalysts.

Evaluation of the effects of light intensity on growth of the benthic dinoflagellate Ostreopsis sp. 1 using a newly developed photoirradiation-culture system and a novel regression analytical method

Benthic dinoflagellates of the genus Ostreopsis are found all over the world in temperate, subtropical, and tropical coastal regions. Our recent studies revealed that a putative “cryptic” species of Ostreopsis ovata is present widely along Japanese coasts. This organism, Ostreopsis sp. 1, possesses palytoxin analogs and thus its toxic blooms may be responsible for potential toxification of marine organisms. To evaluate the bloom dynamics of Ostreopsis sp. 1, the present study examined the growth responses of Ostreopsis sp. 1 strain s0716 to various light intensities (photon flux densities: μmolphotonsm−2s−1) using a newly devised photoirradiation-culture system. This novel system has white light-emitting diodes (LEDs) capable of more closely simulating the wavelength spectrum of light entering the oceanic water column than do fluorescent tubes and halogen lamps. In this system, the light intensity of the white LEDs was reduced through two polarizing filters by varying the rotation angles of the filters. Thereby, the new system was capable of culturing microalgae under well-controlled light intensity conditions. Ostreopsis sp. 1 grew proportionally when light intensity was increased from 49.5 to 199μmolphotonsm−2s−1, but its growth appeared to be inhibited slightly at ≥263μmolphotonsm−2s−1. The relationship between observed growth rates and light intensity was calculated at R>0.99 (P<0.01) using a regression analysis with a modified equation of the photosynthesis-light intensity (P-L) model. The equation determined the critical light intensities for growth of Ostreopsis sp. 1 and the organism's growth potential as follows: (1) the threshold light intensity for growth: 29.8μmolphotonsm−2s−1; (2) the optimum light intensity (Lm) giving the maximum growth rate (μmax=0.659 divisions day−1): 196μmolphotonsm−2s−1; (3) the optimum light intensity range (Lopt) giving ≥95% μmax: 130–330μmolphotonsm−2s−1; (4) the semi-optimum range (Lsopt) giving ≥80% μmax: 90 to over 460μmolphotonsm−2s−1. The Lsopt represents 4.5–23% ambient light intensity present in surface waters off of a temperate region of the Japanese coast, Tosa Bay; putatively, this semi-optimum range of light intensity appears at depth of 12.9–27.8m. Considering these issues, our data indicate that Ostreopsis sp. 1 in coastal environments may form blooms at ca. ∼28m depth in regions along Japanese coasts.

Reproductive performance of Propylea japonica (Coleoptera: Coccinellidae) under various light intensities, wavelengths and photoperiods

Cocccinellid beetles are largely diurnal species that are known to utilize visual cues in foraging and reproduction and to respond in specific ways to various light conditions. The present study evaluated the mating behavior and reproductive performance of Propylea japonica (Thunberg), a species indigenous to Asia, under various conditions of light intensity, photoperiod, and wavelength. Video-recording was used to continuously observe mating pairs for 24 h and a night vision system was employed to record nocturnal activity. Subsequently, males were removed and eggs were collected from females for 10 days and held under the same photic condi- tions to determine their fertility. The frequency and duration of copula varied among photic regimes in all experiments and tended to be negatively correlated, but more copulations occurred in photophase than in scotophase. White light at 1500 lux yielded higher egg pro- duction when compared to other light intensities, but egg fertility was higher at lower light intensities and highest in complete darkness, a result inferred to reflect egg sensitivity to light. Both fecundity and fertility were greater when 1500 lux white light was provided in a 16L : 8D photoperiod compared to shorter days. Green light yielded the highest net fertility compared to other wavelengths. A scheme is proposed to optimize photic conditions for reproductive adults of P. japonica and their eggs in colonies mass-reared for biological control applications.