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Walleye (Sander vitreus) are an ecologically important species managed for recreational, tribal, and commercial harvest. Walleye prefer cool water and low light conditions, and therefore changing water temperature and clarity potentially impacts walleye habitat and populations across the landscape. Using survey data collected from 1993 to 2018 from 312 lakes in Minnesota, we evaluated the relationship between thermal-optical habitat and the relative abundance of small (0-300 mm), medium (300450 mm), and large (450 + mm) walleye. Thermal-optical habitat was positively correlated with the relative abundance of small and medium walleye but not large walleye. Walleye were more abundant in larger, naturally reproducing lakes opposed to smaller, stocked lakes. Thermal-optical habitat changed in 59% of lakes since 1980 (26% increasing and 33% decreasing) and appears to be driven primarily by changes in water clarity and thus optical habitat area. Our study provides important insights into local and regional drivers that influence walleye populations that can be used to assist fisheries managers in setting population goals and managing harvest. Key words: hierarchical models, walleye, thermal-optical habitat, safe operating space, water clarity, temperature, 1. Introduction In dynamic ecosystems, management regimes that account for fluctuations in habitat availability can increase resilience to disturbance (Hansen et al. 2015). However, managed aquatic resources often encompass broad [...]

Our objective was to study how changes in the light spectra affect growth; the concentration of carbohydrate, chlorophyll, carotenoid, terpene, alkaloid, and phenolic compounds; and the emissions of BVOC (biogenic volatile organic compound) of Norway spruce (Picea abies (L.) Karst.) seedlings. This study was conducted during the growth of the third needle generation in plant growth chambers. The plants were exposed to two light spectra with equal photon flux densities but different proportions of blue light (400-500 nm) produced by LED (light-emitting diode) lamps: (i) control (white light +12% blue light) and (ii) increased blue light (+B) (white light + 45% blue light). The +B treatment increased the concentrations of total flavonoids and acetophenones in needles. The major changes in the phenolic profile were an accumulation of astragalin derivatives and the aglycone of picein. The +B treatment also decreased concentrations of the main alkaloid compound, epidihydropinidine, and its precursor, 2-methyl-6-propyl-1,6-piperideine; the emission rates of limonene, myrcene, and total monoterpenes; and the concentrations of a few terpenoid compounds, mainly in stems. Growth as well as the carbohydrates and pigments present in the needles were not affected. The results suggest that supplemental blue light shifts carbon allocation between secondary metabolism routes--from alkaloid and terpenoid synthesis to flavonoid and acetophenone synthesis. The changes may affect herbivory and abiotic stress tolerance of Norway spruce. Key words: blue light, Norway spruce, biogenic volatile organic compounds, phenolic compounds, alkaloids. Notre objectif consistait a etudier de quelle facon les changements dans le spectre lumineux influencent la croissance, la concentration des hydrates de carbone, de la chlorophylle, des carotenoides, des terpenes, des alcaloides et des composes phenoliques, ainsi que les emissions de composes organiques volatiles biogeniques chez des semis d'epicea commun (Picea abies (L.) Karst.). Cette etude a ete effectuee en phytotrons durant la croissance des aiguilles de troisieme generation. Les plants ont ete exposes a deux spectres lumineux avec une densite egale du flux photonique qui se distinguaient principalement par la proportion de lumiere bleue (400-500 nm) produite par des lampes a DEL (diode electroluminescente) : (i) temoin (lumiere blanche + 12 % de lumiere bleue) et (ii) plus forte proportion de lumiere bleue (+B) (lumiere blanche + 45 % de lumiere bleue). Le traitement +B a augmente la concentration totale des flavonoides et des acetophenones dans les aiguilles. L'accumulation de derives de l'astragaline et de l'aglycone de la piceine est le changement majeur observe dans le profil des composes phenoliques. Le traitement +B a aussi reduit la concentration du principal compose alcaloide, l'epidihydropinidine et son precurseur, la 2-methyl-6-propyl-1,6-piperideine, les taux d'emission du limonene, du myrcene et des monoterpenes totaux, ainsi que la concentration de quelques composes terpenoides, principalement dans la tige. La croissance, ainsi que les pigments et les hydrates de carbone presents dans les aiguilles n'ont pas ete modifies. Les resultats indiquent que le supplement de lumiere bleue modifie l'allocation du carbone vers les sentiers metaboliques secondaires, de la synthese des alcaloides et des terpenoides vers la synthese des flavonoides et des acetophenones. Ces changements pourraient avoir un impact sur la tolerance de l'epicea commun aux herbivores et aux stress abiotiques. [Traduit par la Redaction] Mots-cles : lumiere bleue, epicea commun, composes organiques volatiles biogeniques, composes phenoliques, alcaloides., Introduction Quality and quantity of light are primary factors affecting plant germination, morphogenesis, growth, reproduction, and defence. Several photoreceptors participate in perceiving different wavelengths of light, such as phototropins and [...]

Understanding microsite preferences of species at the sapling stage is crucial for successful forest restoration, as efforts can be concentrated onto the most promising sites, and invaded sites can be manipulated toward more suitable conditions for target species. The Hawaiian Lowland Wet Forest is a highly endemic and endangered ecosystem that has received limited attention in terms of research on recruitment dynamics. Our study combined density records and sapling-based measurements within a forest reserve, an invaded forest, a traditional restoration project and a novel restoration project. We recorded substrate type, soil depth, surface roughness, and light availability for 382 saplings of the four native tree species Metrosideros polymorph'a, Myrsine lessertiana, Pipturus albidus, and Psychotria hawaiiensis, and 146 spots where the target species were absent. The invaded forest had the lowest native sapling density, lower light availability, and lower surface roughness than the remaining management units. The novel restoration project had more moss/nurselog sites and higher light availability than the remaining management units. The traditional restoration project was mainly characterized by rocky substrate. Metrosideros and Pipturus showed significantly higher light demand than Myrsine and Psychotria. Pipturus was associated with rough microsites and Metrosideros with moss/nurselog substrates. Our findings suggest that restoration strategies considering manipulation of the canopy light environment and microsite preferences of target species can better facilitate native recruitment into heavily invaded forests. Keywords: abiotic microsite preferences, restoration ecology, Metrosideros polymorpha, Psychotria hawaiiensis, Pipturus albidus, Myrsine lessertiana, forest restoration planning, THE ABUNDANCE AND DIVERSITY OF SAPLINGS in a forest ecosystem provide information about future forest conditions as forest composition and dynamics are predominantly influenced by variation in the survival of [...]

Light environment estimates derived from hemispherical photography are known to be affected by variations in sky illumination. During photo acquisition, rapid changes in sky illumination can occur and will result in changes in detected canopy gap size and frequency. Any resulting problems in image consistency will become more serious with increased time lags between setting the reference exposure and hemispherical photograph acquisition. We showed that if the camera exposure setting was kept constant during photo acquisition, the estimated diffuse transmittance would be greatly influenced by sky illumination change. We developed a new pixel thresholding method that calculated the optimal threshold value for the separation of sky and plant pixels as a function of the above-canopy photosynthetic photon flux density (PPFD). We tested the performance of our method for estimating transmittance against two established methods that assume exposure to be held constant to two stops higher than the reference exposure. Our method compensates for changes in sky illumination, producing a smaller pixel threshold value when sky illumination decreases and a larger pixel threshold value when photographs are taken under increased sky illumination. The new method achieved accurate and reproducible results, even in situations where under- or over-exposure was caused by changes in sky illumination during photo acquisition. Key words: sky illumination, gap fraction, light availability, indirect site factor, exposure. On sait que les estimations de l'environnement lumineux derivees de photographies hemispheriques sont influencees par les variations de l'eclairement du ciel. Durant l'acquisition de photos, des variations rapides de l'eclairement du ciel peuvent survenir et n'importe quel changement dans le degre de luminosite du ciel se traduira par des changements dans la taille et la frequence des trouees detectees dans le couvert forestier. Les problemes de coherence des images qui en resultent vont devenir plus serieux avec l'allongement des delais entre le reglage de l'exposition de reference et l'acquisition des photographies hemispheriques. Nous avons montre que si le reglage de l'exposition de la camera etait maintenu constant pendant l'acquisition de photos, la transmittance diffuse estimee serait fortement influencee par la variation de l'eclairement du ciel. Nous avons developpe une nouvelle methode de seuillage d'image qui calcule la valeur seuil optimale pour separer les pixels du ciel de ceux des plantes en fonction de la densite de flux photonique photosynthetique (PPFD) au-dessus du couvert forestier. Nous avons teste la performance de notre methode pour estimer la transmittance en la comparant a deux methodes etablies qui assument que l'exposition est maintenue constante deux crans plus haut que l'exposition de reference. Notre methode compense pour les variations de l'eclairement du ciel et determine une valeur seuil plus petite lorsque l'eclairement du ciel diminue et une valeur seuil plus grande lorsque les photos sont prises avec un eclairement du ciel plus prononce. La nouvelle methode permet d'obtenir des resultats exacts et reproductibles, meme dans les situations ou la sous-exposition ou la surexposition sont causees par des variations de l'eclairement du ciel pendant l'acquisition de photographies. [Traduit par la Redaction] Mots-cles : eclairement du ciel, fraction de trouee, disponibilite de la lumiere, facteur indirect de site, exposition., Introduction Light is often a resource limiting the performance of plants and regulating species interactions in structurally complex communities such as forests (Denslow 1987). Data on light availability are essential [...]

Light is a key environmental factor affecting anthocyanin biosynthesis. Our previous study demonstrated that 'Lanshan Hexian' is a light-sensitive eggplant cultivar, but its regulatory mechanism is unknown. Here, delphinidin-3-[4-(cis-p-coumaroyl)-rhamnosyl-glucopyranoside]-5-glucopyranoside and delphinidin-3-[4-(trans-p-coumaroyl)-rhamnosyl-glucopyranoside]-5-glucopyranoside were identified as the main anthocyanin components in Lanshan Hexian by ultra-performance liquid chromatography-tandem mass spectrometry. Three time points of anthocyanin accumulation, including the start point (0 day), fastest point (5 days), and highest point (12 day), were investigated by using ribonucleic acid sequencing and iTRAQ technology. The corresponding correlation coefficients of differentially expressed genes, and differentially expressed proteins were 0.6936, 0.2332, and 0.6672. Anthocyanin biosynthesis was a significantly enriched pathway, and CHI, F3H, 3GT, 5 GT, and HY5 were regulated at both transcriptional and translational levels. Moreover, some transcription factors and photoreceptors may participate in light-induced anthocyanin biosynthesis like the known transcription factors MYB113 and TT8. The transient expression assay indicated that SmMYB35, SmMYB44, and a SmMYB86 isoform might involve in the light-induced anthocyanin biosynthesis pathway. Finally, a regulatory model for light-induced anthocyanin biosynthesis in eggplant was constructed. Our work provides a new direction for the study of the molecular mechanisms of light-induced anthocyanin biosynthesis in eggplant. [ABSTRACT FROM AUTHOR]

Recent observational studies form oligotrophic waters provide ample evidence that mixotrophic flagellates often account for the bulk of bacterivory. However, we lack a general framework that allows a mechanistic understanding of success of mixotrophs in the competition with heterotrophic bacterivores. This is especially needed for integrating mixotrophy in models of the microbial loop. Based on general tradeoffs linked to the combined resource use in mixotrophs (generalist versus specialist), we propose a concept where mixotrophs are favored by conditions of high light - low losses, corresponding to the situation found in the surface waters of oligotrophic oceans. Under such conditions, they can achieve positive net growth at very low resource levels, allowing simultaneous competition with specialized protists. Conversely, heterotrophic bacterivores and photoautotrophs should be especially favored in more productive and low-light conditions. We show experimentally that the combined effect of light and loss rates (dilution) predicts the success of mixotrophic bacterivorous flagellates. Moreover, our results suggest that total bacterivory, contrary as seen in the traditional microbial loop concept, has a more intricate coupling to light. [ABSTRACT FROM AUTHOR]

Light use efficiency (LUE) models offer an effective way for regional gross primary productivity (GPP) estimation. However, LUE is not easily determined at the landscape level due to its complexity and dependence on various environmental factors. One possible strategy to avoid the requirement for assessing environmental stressors is using the photochemical reflectance index (PRI) to determine LUE via the epoxidation state of the xanthophyll cycle. Integration of such measurements into GPP models could lead to more realistic GPP estimates of landscape level. Conventional, “one-leaf” LUE models, however, seem less suitable for integration of such remote sensing observations, as optically derived estimates are dependent on the shadow fraction viewed at a given time. Here, we utilize the two-leaf LUE (TL-LUE) model to parameterize LUE from multiangle PRI observations and compare it with MOD17 approach. Significant relationships were found between LUE (LUE, LUEsun, and LUEshaded) and PRI (PRI, PRIsun, and PRIshaded) over 8- and 16-day time steps. Similarly, R^2 values for the relationships between modeled GPP and observed GPP (EC derived measurements of GPP) were 0.87 (TL-LUE) and 0.81 (MOD17) at deciduous forest and 0.54 (TL-LUE) and 0.46 (MOD17) at evergreen forest for eight-day periods, as well as 0.84 (TL-LUE) and 0.74 (MOD17) at deciduous forest and 0.49 (TL-LUE) and 0.46 (MOD17) at evergreen forest for 16-day periods. Our results are relevant when planning potential future satellite missions to help constrain existing GPP models using remotely sensed data, as such observations will likely be affected by canopy shading effects at the time of observation. [ABSTRACT FROM PUBLISHER]

Colimitation of primary production is increasingly recognized as a dominant process across aquatic and terrestrial ecosystems. In streams, both nutrient availability and light availability have been shown to independently limit primary production, but colimitation by both light and nutrients is rarely considered. We used a series of nutrient-diffusing substrates (NDS) bioassays deployed across a range of light availability conditions in a single-study stream over two summers to determine the light level at which the limiting factor for benthic periphyton accrual transitioned from light to nutrients. Stream periphyton accrual was nutrient-limited in high-light patches, and light-limited in low-light patches, with the transition from being predominantly light-limited to being predominantly nutrient-limited occurring when daily light fluxes exceeded 3.5 mol m day. We quantified light at each NDS bioassay location and at 5 m intervals throughout our two adjacent 160 m study reaches-one in structurally complex old-growth riparian forest and one bordered by more uniform second-growth forest. Although both reaches were colimited overall, the resource (light or nutrients) dominating limitation differed between the two riparian forest age/structure conditions. In the old-growth section, about three quarters of the reach was predominantly nutrient-limited, whereas in the second-growth reach only about a quarter of the streambed was nutrient-limited. In this stream, colimitation of benthic periphyton accrual by light and nutrients at the reach scale was an emergent property of the ecosystem that manifested as a result of high heterogeneity in riparian forest structure. [ABSTRACT FROM AUTHOR]

Estimation of the basal or heterotrophic soil respiration is crucial for determination of whether an ecosystem is emitting or sequestering carbon. A severe bushfire in January 2014 at the Calperum flux tower, operational since August 2010, provided variation in ecosystem respiration and leaf area index as the ecosystem recovered. We propose ecosystem respiration is a function of leaf area index and the y-intercept is an estimate of heterotrophic soil respiration. We calculated an assimilation rate from eddy covariance data for light response functions to calculate ecosystem respiration incorporating suppression of the daytime autotrophic respiration. Ecosystem respiration from light response functions correlated with data processing calculations of ecosystem respiration by OzFluxQC (y0 = 0.161x + 0.0085; Adj. r² = 0.698). The relationship between ecosystem respiration and leaf area index (y0 = 1.43x +0.398; Adj. r² = 0.395) was also apparent. When this approach was compared to field measurements of soil respiration and mass balance calculations from destructive leaf area, leaf area index calculations and litter fall, the year of data corresponding to the year of soil respiration measurements, the y-intercept was 0.432 µmol m-2 s-1 or 163.44 gC m-2 year-1 (y0 = 1.37x + 0.432, Adj. r² = 0.325). The mass balance approach for the net primary productivity when subtracted from the tower NEE estimated heterotrophic soil respiration of 134.59 gC m-2 year-1. This is only 28.9 gC different, therefore the y-intercept approach indeed provides an estimate of heterotrophic soil respiration. [ABSTRACT FROM AUTHOR]

Author Affiliations: Decapitated flatworms glide away from a source of ultraviolet light. Credit: Nishan Shettigar UV-A-induced movement by flatworm How headless worms see the light to steer Decapitated flatworms can [...], Light-sensitive cells, distributed throughout its body, help a simple creature to do the extraordinary. Light-sensitive cells, distributed throughout its body, help a simple creature to do the extraordinary.

Forests exhibit spatial heterogeneity in plant composition and light, which may influence ectomycorrhizal fungal (ECM) communities. We investigated whether light and soil source affect ECM colonization and community properties on red oak (Quercus rubra L.) seedlings. Seedlings were grown under 10%, 45%, and full sunlight in soils removed beneath red oak and eastern hemlock (Tsuga canadensis (L.) Carr.) trees. Between soils, colonization and diversity were significantly greater in intermediate--high versus low light. Across light levels, colonization, richness, and diversity were greater on seedlings grown in oak versus hemlock soils. The frequency of seedlings colonized by three of the four most common morphotypes was more responsive to light in oak versus hemlock soil. Colonization differences between soil sources were associated with differences in richness, which may in turn reflect host specificity and fine root length differences. Increasing colonization with increasing light was associated with increased richness, which in turn may reflect increased carbon allocation to roots. Results suggest that differences in responses of individual ECM morphotypes coupled with host responses to light and soil source may influence ECM colonization and diversity. Changes in ECM colonization and diversity could in turn affect seedling recruitment, especially for seedlings encountering variable light regimes and host species. Dans les forets, l'heterogeneite spatiale de la composition vegetale et de la luminosite peut influencer les communautes de champignons ectomycorhiziens (ECM). Nous avons etudie si la luminosite et la source du sol influencent les proprietes de la communaute et la colonisation des ECM sur les semis de chene rouge (Quercus rubra L.). Les semis ont ete cultives dans differentes conditions de luminosite (10 %, 45 % et 100 % du plein soleil) dans des sols preleves sous des chenes rouges et des pruches du Canada (Tsuga canadensis (L.) Carr.). Dans les differents sols, la colonisation et la diversite etaient significativement plus elevees dans des conditions de luminosite intermediaire a elevee plutot que faible. Parmi les differents niveaux de luminosite, la colonisation, la richesse et la diversite etaient plus elevees sur les semis cultives dans le sol du chene que dans celui de la pruche. La frequence des semis colonises par trois des quatre morphotypes les plus communs reagissait davantage a la luminosite dans le sol du chene que dans celui de la pruche. Les differences de colonisation entre les sources de sol etaient associees a des differences de richesse qui peuvent a leur tour refleter des differences liees a la specificite de l'hote et a la longueur des racines fines. L'augmentation de la colonisation avec l'accroissement de la luminosite etait associee a l'augmentation de la richesse qui peut a son tour refleter une allocation accrue de carbone aux racines. Les resultats indiquent que des differences de reaction des morphotypes d'ECM individuels couplees a la reaction de l'hote a la luminosite et a la source de sol peuvent influencer la diversite et la colonisation des ECM. Les changements dans la diversite et la colonisation des ECM pourraient a leur tour avoir un effet sur le recrutement des semis, particulierement dans le cas des semis confrontes a des especes hotes et a des regimes de luminosite qui varient. [Traduit par la Redaction], Introduction Spatial variation in light availability is a key factor driving differential seedling growth in heterogeneous habitats, such as forest understories (Catovsky and Bazzaz 2000). In addition to direct effects [...]

Growth, photosynthesis, and photoacclimation properties of batch cultures of Pelagomonas calceolata (Pelagophyceae) were compared for 1 week under three different fluctuating light regimes with the same total daily amount of light. Treatments consisted of a sinusoidal diurnal light cycle or a high-frequency fluctuating light simulating two different regimes of vertical mixing (highly fluctuating light [HFL] or fluctuating light [FL]). Three to five samples were taken every day for analysis of pigments, absorption spectrum, variable fluorescence, nonphotochemical quenching (NPQ), electron transport rate vs. light curves, and cell concentration. Pelagomonas achieved the same growth rate during the exponential growth phase under all three light conditions, revealing a high degree of acclimation to light and also suggesting that the daily light dose is the main factor regulating growth and division. Photophysiological adjustments occurred in the cells in response to the three light regimes. Pelagomonas seems to adopt the n-type photoacclimation in HFL, whereas the [sigma]-type photoacclimation is applied in FL. The cells rapidly trigger photoprotective mechanisms such as the xanthophyll cycle and NPQ, even though these do not appear to be able to fully prevent photoinhibition. The enhanced costs for maintenance and repair associated with HFL may have limited the allocation of energy to growth, thus explaining the shorter duration of the exponential growth phase in this regime with respect to the two others.

Light and temperature strongly influence the vertical distribution of the mysid shrimp, Mysis relicta. We monitored the vertical movements and depth selection behavior of mysids exposed to different light intensities and light-temperature gradients in the laboratory and derived a mysid light preference function in units relevant to mysid vision: 'mylux'. Mysids preferred light levels between [10.sup.-8] and [10.sup.-7] mylux (~[10.sup.-6] to [10.sup.-5] lux) and rarely moved into waters of [10.sup.-3] mylux (~0.1 lux) and greater. A model that assumed equal weight and independence of mysid light and temperature preference functions successfully predicted the proportion of mysids found in two different temperature-light combinations in the laboratory. This model also predicted the depth of maximum mysid density to within 2 m on two spring nights and within 5 m on two summer nights of varying moon phase and thermal conditions in Lake Ontario. This study provides novel insights into how temperature and light interact to influence the vertical distribution of mysids. Our model may be used to predict mysid vertical distribution in any deepwater system inhabited by mysids in which the primary mysid predators are visual feeders. La lumiere et la temperature influencent fortement la repartition verticale des mysis, Mysis relicta. Nous avons note les deplacements verticaux et le comportement de selection de profondeur de mysis exposes a differentes intensites lumineuses et a des gradients de lumiere-temperature en laboratoire et avons mis au point une fonction de preference lumineuse des mysis en unites [much less than] mylux [much greater than] qui sont compatibles avec la vision des mysis. Les mysis preferent des intensites lumineuses de [10.sup.-8] a [10.sup.-7] mylux (~[10.sup.-6] a [10.sup.-5] lux) et penetrent rarement dans des eaux de [10.sup.-3] mylux (~0,1 lux) ou plus. Un modele qui presume un poids egal et une independance des fonctions de preference de lumiere et de temperature des mysis predit avec succes les proportions de mysis retrouvees dans deux combinaisons differentes de temperature-lumiere en laboratoire. Ce modele predit aussi la profondeur de densite maximale des mysis avec une precision de 2 m lors de deux nuits de printemps et une precision de 5 m lors de deux nuits d'ete de phase lunaire et de conditions thermiques differentes au lac Ontario. Notre etude ouvre des perspectives nouvelles sur l'influence de l'interaction de la temperature et de la lumiere sur la repartition verticale des mysis. Notre modele peut servir a predire la repartition verticale des mysis dans n'importe quel systeme d'eau profonde habite par les mysis et dans lequel les principaux predateurs des mysis se nourrissent a vue. [Traduit par la Redaction], Introduction Zooplankton diel vertical migration (DVM) is a widely occurring and well-documented phenomenon in both marine and freshwater ecosystems (Hamner 1988; Haney 1988). Although a vast literature exists on the [...]

Simultaneous gradients of phosphorus and light were applied in experimental streams to develop quantitative relationships between these two important abiotic variables and the growth and composition of benthic microalgae. Algal biovolume and whole-stream metabolism responded hyperbolically to phosphorus enrichment, increasing approximately two-fold over the 5-300 [micro]g [L.sup.-1] range of experimental phosphorus concentrations. The saturation threshold for phosphorus effects occurred at 25 [micro]g [L.sup.-1] of soluble reactive phosphorus (SRP). Light effects were much stronger than those of phosphorus, resulting in a nearly ten-fold increase in algal biovolume over the 10-400 [micro]mol photons [m.sup.-2] [s.sup.-1] range of experimental irradiances. Biovolume accrual was light-saturated at 100 [micro]mol photons [m.sup.-2] [s.sup.-1] (5 mol photons [m.sup.-2] [d.sup.-1]). Light effects were diminished by low phosphorus concentrations, and phosphorus effects were diminished by low irradiances, but evidence of simultaneous limitation by both phosphorus and light at subsaturating irradiances was weak. Contrary to the light : nutrient hypothesis, algal phosphorus content was not significantly affected by light, even in the lowest SRP treatments. However, algal nitrogen content increased substantially at lower irradiances, and it was very highly correlated with algal chlorophyll a content. Phosphorus enrichment in streams is likely to have its largest effect at concentrations

Numerical experiments are carried out for a plane wave propagating in the atmospheric turbulence for a weak to strong fluctuation condition, i.e., the Rytov index being in a large range of 2 x [10.sup.-3] to 20. Mainly two categories of propagation events are explored for the same range of Rytov index. In one category the propagation distance and also the Fresnel length are kept fixed with the turbulence strength changing. In the other the turbulence strength is kept fixed with the distance changing. The statistical characteristics of the scintillation index, the maximum and minimum of the intensity, the fractal dimension of the intensity image, and the number density of the phase singularity are analyzed. The behaviors of the fractal dimension and the density of the phase singularity present obvious differences for the two categories of propagation. The fractal dimension depends both on the Rytov index and the Fresnel length. In both weak and strong fluctuation conditions the dimension generally increases with the Rytov index, but is at minimum at the onset region. The phase singularity density is coincident with the theoretical results under a weak fluctuation condition, and has a slowly increasing manner with the Rytov index in the strong fluctuation condition. The dependence on the Fresnel size is confident and there is no saturation for the phase singularity. OCIS codes: 010.1300, 010.1330, 010.1290, 010.7060.

Light is one of the most important environmental factors affecting flavonoid biosynthesis in plants. The absolute dependency of light to the plant development has driven evolvement of sophisticated mechanisms to sense and transduce multiple aspects of the light signal. Light effects can be categorized in photoperiod (duration), intensity (quantity), direction and quality (wavelength) including UV-light. Recently, new information has been achieved on the regulation of light-controlled flavonoid biosynthesis in fruits, in which flavonoids have a major contribution on quality. This review focuses on the effects of the different light conditions on the control of flavonoid biosynthesis in fruit producing plants. An overview of the currently known mechanisms of the light-controlled flavonoid accumulation is provided. R2R3 MYB transcription factors are known to regulate by differential expression the biosynthesis of distinct flavonoids in response to specific light wavelengths. Despite recent advances, many gaps remain to be understood in the mechanisms of the transduction pathway of light-controlled flavonoid biosynthesis. A better knowledge on these regulatory mechanisms is likely to be useful for breeding programs aiming to modify fruit flavonoid pattern. [ABSTRACT FROM AUTHOR]

Light and nutrient availability are assumed to largely control the dynamics and trophic efficiency of marine planktonic food webs, and are expected to be influenced by climate change (i.e. changes in stratification due to global warming). During an 8-day mesocosm experiment, we investigated the propagation of light energy up to the copepod trophic level in ultra-oligotrophic Eastern Mediterranean waters. Using mesocosms with light treatments corresponding to ca. 40% (L1) and 4.5% (L4) of the incident light intensity (simulating light conditions at 10 and 50–60 m depths, respectively), we assessed the feeding behaviour of the dominant copepod Clausocalanus furcatus every second day. We hypothesized that increased availability of copepod food at higher light levels would result in increased copepod ingestion rates and selectivity. Our results showed that copepod prey (microbial biomass>5 μm) had only a small increase in the L1 and daily rations (DRs) of C. furcatus were similar among treatments (usually <15% of body carbon). Nevertheless, microplankton was clearly selected in L1, having double the contribution in the DR of C. furcatus compared with L4. A more balanced selective feeding pattern was observed in L4, with nanoplankton also being important in the diet. An increase in the copepod stock in the L1 compared with L4, observed at the end of the experiment, is likely associated with the light-mediated effects on C. furcatus feeding behaviour. We suggest that the importance of light availability on the efficiency of the marine planktonic food web should be further considered by climate change predictive models. [ABSTRACT FROM PUBLISHER]