Variation In Chlorophyll Content Research Articles

A Comparison of Three Isolines of Cotton Differing in Fiber Color for Yield, Quality, and Photosynthesis

Naturally colored cotton (Gossypium hirsutum L.) fibers (CCFs) are eco‐friendly for the textile industry because they omit the dyeing process and reduce harmful effluent liquor. However, the low yield and quality of CCFs have greatly affected their development. Limited information is available on the reasons for the low yield and quality of CCFs. The aim of this 2‐yr investigation was to compare variations in chlorophyll concentration, net photosynthesis rate, monosaccharide concentration, and fiber yield and quality among white‐fiber cotton (WFC), brown‐fiber cotton (BFC), and green‐fiber cotton (GFC). White‐fiber cotton had the highest lint yield, which was on average 33.6 and 41.9% higher than that of BFC and GFC, respectively. Other yield components such as boll number and boll weight had similar trends in both years. The fiber length of GFC and BFC was reduced by 17.4 and 11.1%, respectively, compared with that of WFC. These results indicated that GFC had the lowest fiber yield and quality. Leaf chlorophyll concentration, net photosynthesis rate, and fructose and glucose concentrations of GFC were slightly higher than those of WFC, indicating its active photosynthesis. However, its vigorous vegetative growth had reduced its reproductive growth, partly resulting in low yield and quality. Brown‐fiber cotton had the lowest leaf chlorophyll concentration and other photosynthetic indexes, leading to a lower amount of photosynthetic product and, hence, yield and quality.

Model-based estimates of Calanus finmarchicus abundance in the Gulf of Maine

Ocean observing systems and satellites routinely collect a wealth of information on physical conditions in the ocean. With few exceptions, such as chlorophyll concentrations, infor- mation on biological properties is harder to measure autonomously. Here, we present a system to produce estimates of the distribution and abundance of the copepod Calanus finmarchicus in the Gulf of Maine. Our system uses satellite-based measurements of sea surface temperature and chloro- phyll concentration to determine the developmental and reproductive rates of C. finmarchicus. The rate information then drives a population dynamics model of C. finmarchicus that is embedded in a 2-dimensional circulation field. The first generation of this system produces realistic information on interannual variability in C. finmarchicus distribution and abundance during the winter and spring. The model can also be used to identify key drivers of interannual variability in C. finmarchicus. Experiments with the model suggest that changes in initial conditions are overwhelmed by variabil- ity in growth rates after approximately 50 d. Temperature has the largest effect on growth rate. Elevated chlorophyll during the late winter can lead to increased C. finmarchicus abundance during the spring, but the effect of variations in chlorophyll concentrations is secondary to the other inputs. Our system could be used to provide real-time estimates or even forecasts of C. finmarchicus distri- bution. These estimates could then be used to support management of copepod predators such as herring and right whales.

Spatial distribution and seasonal variability in chlorophyll concentrations in the coastal Lake Gardno (Poland)

Abstract In 2006 the spatial distribution and seasonal variations in chlorophyll concentration were measured, at about two-week frequency, in Lake Gardno. In general, chlorophyll concentrations in the central part of the lake were high throughout the growth season. The minimum chlorophyll concentration was recorded in March (7.5 mg m-3), and the maximum value in September (303 mg m-3). Higher chlorophyll concentrations and lower temporal variability were measured in the central part of the lake, compared to lower concentrations and higher variability in the vicinity of the Łupawa River input to the lake. Chlorophyll concentrations were measured fluorometrically along several vertical and horizontal profiles, enabling direct observations of the dynamics of changing chlorophyll concentrations in Lake Gardno throughout the year.

Photosynthesis and respiration of hermatypic zooxanthellate Red Sea corals from 5-75-m depth

Hermatypic zooxanthellate corals depend on light for photosynthesis. As such, they will not grow at depths deeper than 100 m. Submersible respirometers were used to monitor changes in oxygen concentration for five corals species, Favia favus, Fungia scutaria, Lobophyllia sp., Mycedium sp., and Stylophora pistillata. Variations in chlorophyll concentrations, zooxanthellae cell densities, photosynthesis, and respiration rates were detected in these coral species. Two clusters emerged when correlated with deep water, indicating different populations. The first group was restricted to the surface-40 m depth and the second to the 40-75-m depth. Light intensity for saturating photosynthesis Ek was less than 320 μmol q m-2 s-1 for all species and decreased with depth for most of them.

Mining a Sea of Data: Deducing the Environmental Controls of Ocean Chlorophyll

Chlorophyll biomass in the surface ocean is regulated by a complex interaction of physiological, oceanographic, and ecological factors and in turn regulates the rates of primary production and export of organic carbon to the deep ocean. Mechanistic models of phytoplankton responses to climate change require the parameterization of many processes of which we have limited knowledge. We develop a statistical approach to estimate the response of remote-sensed ocean chlorophyll to a variety of physical and chemical variables. Irradiance over the mixed layer depth, surface nitrate, sea-surface temperature, and latitude and longitude together can predict 83% of the variation in log chlorophyll in the North Atlantic. Light and nitrate regulate biomass through an empirically determined minimum function explaining nearly 50% of the variation in log chlorophyll by themselves and confirming that either light or macronutrients are often limiting and that much of the variation in chlorophyll concentration is determined by bottom-up mechanisms. Assuming the dynamics of the future ocean are governed by the same processes at work today, we should be able to apply these response functions to future climate change scenarios, with changes in temperature, nutrient distributions, irradiance, and ocean physics.

Retrieving seasonal variation in chlorophyll content of overstory and understory sugar maple leaves from leaf-level hyperspectral data

Leaf chlorophyll content is a useful parameter for assessing vegetation physiological status and dominates the spectral signal of leaf and canopy reflectance at visible wavelengths. Using hyperspectral instruments, we quantified leaf chlorophyll content and optical properties for 255 overstory and understory leaf samples through the growing season in a mature sugar maple (Acer saccharum) stand. Strong seasonal and canopy-height-related differences were observed in both leaf chlorophyll content and leaf reflectance and transmittance spectra. Seasonal and canopy-height-related variation in leaf spectra were closely related to leaf chlorophyll content. We estimated leaf chlorophyll content using two approaches, namely empirical spectral indices, and a mathematical inversion of the leaf optical model PROSPECT. Both estimates were highly correlated with the measured leaf chlorophyll content; however, the spectral indices resulted in greater accuracy, with the best-performing index (modified simple ratio) showing an accuracy of R2 = 0.88 and RMSE = 3.94 µg/cm2. A leaf thickness factor was introduced in the PROSPECT model to take into account the effects of changes in leaf structure on light absorption. The model inversion was improved after incorporating leaf thickness factors based on observed seasonal and canopy-height-related variation in leaf thickness. The improved model had the best performance, with an accuracy of R2 = 0.93 and RMSE = 3.09 µg/cm2 in retrieved leaf chlorophyll concentration in comparison with laboratory measurements.

Importance of the polarization in the retrieval of oceanic constituents from the remote sensing reflectance

The influence of marine particles on the polarized radiation exiting the ocean is studied, and the implications for the retrieval of particulate concentration from remotely sensed data are investigated. Simulations were carried out using a vector radiative transfer model. Open ocean and coastal waters conditions were examined separately. In phytoplankton dominated waters, the polarized reflectance is virtually insensitive to the variations in chlorophyll concentration when observing at the top of atmosphere. The polarization effects induced by phytoplankton cells are too weak compared to those induced by the air‐water interface and the atmospheric particles (especially molecules) to significantly contribute to the polarized reflectance at this level of atmosphere. The use of the polarized information at short wavelengths is thus proposed to improve the retrieval of the spectral variation of the aerosol model in atmospheric correction algorithms. In coastal zones, the sensitivity of the polarized signal to the water content is much greater. The analysis demonstrates that the measurement of the polarized reflectance just above the sea surface may not be relevant to reduce the skylight reflection effects when the water mass is mainly dominated by highly refractive particles. It is shown that polarization measurements can be of great interest to separate the fraction of inorganic particles from biogenic cells. This study also highlights that an empirical‐based inversion approach relying on the polarized reflectance measured in the green and at longer wavelengths could be efficient to retrieve the concentration of inorganic particles regardless of the phytoplankton content in coastal waters.

Changes in the first derivatives of leaf reflectance spectra of various plants induced by variations of chlorophyll content

Reflectance spectra of leaves of winter wheat, maize, sugar beet and wild vine have been measured. Chlorophyll variations induce changes in the first derivatives of the reflectance spectra. A correlation of various derivative indices such as D(725)/D(702), D(lw)/D(sw), D(lw)/D(702), D(725)/D(sw,)D(715)/D(702), D(m)/D(sw), D(m)/D(702) and D(715)/D(sw) with chlorophyll content was tested, when D is the relative height of the first derivative, the subscript numbers give the wavelength in nm for fixed determination and lw, m and sw are the determination in the long-, medium- and short-wavelength maximum, respectively. The short- and long-wavelength maxima are in the range of 690-730 nm, the medium peak is within the other two, in the range of 710-715 nm. Regression models have been obtained for all types of indices and for all studied plant species. The most promising regression model has been selected. This type of model has been similar for maize, sugar beet and wild vine; therefore, a unified regression model is shown to be applicable for chlorophyll estimation in leaves of these species. The regression model for winter wheat was essentially distinct from both individual and unified models for other studied plants. Reasons for the difference in regression models for various species are discussed.

Variation in chlorophyll content, anatomical traits and agronomic performance of wheat genotypes differing in spot blotch resistance under natural epiphytotic conditions

Spot blotch caused by Cochliobolus sativus is a serious constraint to wheat (Triticum aestivum) yields in South Asia. A study was conducted at Rampur, Nepal, during 2002 and 2003 using five wheat genotypes (Sonalika, BL1473, Kanchan, Nepal 297 and NL 750) differing in spot blotch resistance to assess the effect of disease on loss of chlorophyll measured as soil plant analysis development (SPAD) over time characterised by the area under SPAD value decline curve (AUSDC) and the area under disease progress curve (AUDPC), and to investigate the association between disease severity and leaf anatomical traits. The SPAD value was measured using a Minolta SPAD-502 chlorophyll meter on three different dates in 10 randomly tagged flag leaves in each plot postanthesis to determine AUSDC. Eight anatomical characters were examined in the flag leaf. The AUDPC showed a significant negative correlation with the width of large vascular bundles, percentage of small vascular bundles with two girders and the number of large veins. The AUDPC was positively correlated with the distance between adjacent vascular bundles and leaf thickness. The SPAD and AUSDC values were higher in spot blotch resistant and tolerant genotypes. The findings underline the importance of mesophyll structure and chlorophyll content in spot blotch resistance in wheat. This is useful information for developing spot blotch resistant wheat.

Long-term dynamics of chlorophyll concentration in the ocean surface layer (by space data)

To preserve the biosphere and to use it efficiently, it is necessary to gain a deep insight into the dynamics of the primary production process on our planet. Variability of chlorophyll concentration in the ocean is one of the most important components of this process. These investigations are, however, very labor-consuming, because of the difficulties related to the accessibility of the water surface and its large size. In this work long-term changes in chlorophyll concentration in the surface layer of the ocean have been analyzed on the basis of the CZCS data for 7.5 years from 1979 to 1986 and the SeaWiFS data from 1997 to 2004. It has been shown that the average chlorophyll concentration calculated in all investigated areas varies moderately. However, when analyzing spatially local trends, the areas have been detected that have significant rise and fall of chlorophyll concentrations. Some interesting features of the long-term dynamics of chlorophyll concentration have been found. The opposite directions of long-term trends (essential increase or decrease) cannot be explained only by large-scale hydrological phenomena in the ocean (currents, upwellings, etc.). The measured chlorophyll concentration results from the balance between production and destruction processes. Which process dominates is determined by various hydrophysical, hydrobiological, and climatic processes, leading to sharp rises or falls of the concentration. It is important to estimate the scale of the areas in which this or that process dominates. Therefore, the study addresses not only the dynamics of the mean value but also the dynamics of the areas in which the dominance of certain factors has led to a sharp fall or rise in chlorophyll concentration. Thus, the obtained results can be used to estimate long-term changes in the ocean biota.

Temporal variability in phytoplankton pigments, picoplankton and coccolithophores along a transect through the North Atlantic and tropical southwestern Pacific

Biogeochemical processes in the sea are triggered in various ways by chlorophyll-containing phytoplankton groups. While the variability of chlorophyll concentration at sea has been observed from satellites for several years, these groups are known only from cruises which are limited in space and time. The Geochemistry, Phytoplankton and Color of the Ocean programme (GeP&CO) was set up to describe and understand the variability of phytoplankton composition on large spatial scales under a multi-year sampling strategy. It was based on sea-surface sampling along the route of the merchant ship Contship London which travelled four times a year from Le Havre (France) to Nouméa (New Caledonia) via New York, Panama and Auckland. Observations included the measurement of photosynthetic pigments, counts of picoplanktonic cells by flow cytometry (Prochlorococcus, Synechococcus, and picoeucaryotes) and counting and identification of coccolithophores. The results confirmed that tropical areas have low seasonal variability and are characterized by relatively high divinyl-chlorophyll a and zeaxanthin concentration and that the variability is strongest at high latitudes where the phytoplankton biomass and population structure are found to have large seasonal cycles. Thus, the spring bloom in the North Atlantic and an austral winter bloom north of New Zealand are marked by chlorophyll concentrations which are often higher than 0.5 μg l −1 and by high concentration of fucoxanthin (a pigment used as an indicator for diatoms), while summer populations are dominated by Prochlorococcus sp. and have low chlorophyll concentrations. Apart from this yearly bloom at temperate latitudes, fucoxanthin is scarce, except in the equatorial upwelling zone in the eastern Pacific Ocean, where it is found in moderate amounts. In this region, relatively high chlorophyll concentrations extend generally as far as 14°S and do not respond to the seasonal strengthening of the equatorial upwelling during the austral winter. Prochlorococcus, which is known to dominate in oligotrophic tropical seas and to disappear in cold conditions, in fact has its minimum during the spring bloom in the North Atlantic, rather than during the winter. Coccolithophores are ubiquitous, showing a succession of species in response to oceanic conditions and provinces. 19′Hexanoyloxyfucoxanthin, the pigment generally considered as an indicator of coccolithophores, is relatively abundant at all times and in all regions, but its abundance is generally not tightly correlated with that of coccolithophores. The regional differences revealed by these results are in overall agreement with Longhurst's division of the ocean into ecological provinces.

Variability of chlorophyll concentration in the Arabian Sea and Bay of Bengal as observed from SeaWiFS data from 1997–2000 and its interrelationship with Sea Surface Temperature (SST) derived from NOAA AVHRR

Variability of chlorophyll concentration in the Arabian Sea and Bay of Bengal has been studied using SeaWiFS eight‐day average, 9 km processed data for the period 1997–2000. The interrelationship with sea surface temperature (SST) was studied with the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) derived, best SST product. The chlorophyll pattern shows in general high concentrations during February to March in the Arabian Sea and November to December in the Bay of Bengal. Year‐to‐year variations in temperature show an inverse relation with chlorophyll, at different locations, even on a monthly basis. However, the intraannual variability in chlorophyll at different locations shows differences in the relationship with SST. The Arabian Sea showed an inverse relationship at most of the locations, while a positive relationship was observed in the northwest region during October to December and an inverse relationship during January to April. The Bay of Bengal showed positive relationships at northeast locations, whereas no definite assessment could be made for other locations due to the narrow range of chlorophyll concentration.A longer time series (∼10 years) will be required to establish a more concrete relationship but definitely consistent patterns are emerging from this study. The results form an additional dimension to the criteria for partitioning the ocean, required for global productivity or biophysical coupled modelling.

Effects of chlorophyll concentration and temperature variation on the reproduction and survival of Temora longicornis (Copepoda, Calanoida) in the Eastern English Channel

The influence of temperature and chlorophyll concentration on egg production, hatching success, female survival and body size of the copepod Temora longicornis was investigated in situ in the coastal waters of the Eastern English Channel. Twenty samples were collected between February and July 2003 three to four times per month. The maximum daily level of egg production of 75.5 eggs female −1 was observed in March, with minima of 10 eggs female −1 in February and July. Between February and March egg production increased with chlorophyll concentration. At the end of March a decrease in egg production corresponded to a strong increase in chlorophyll concentration that indicated a Phaeocystis-dominated bloom. After this period egg production closely followed the temporal variation in chlorophyll concentration with a maximum of 55.3 eggs female −1 in April during a second peak of chlorophyll concentration. Hatching success varied between 60% and 80% and was not influenced by chlorophyll concentration, in situ temperature or any other biological parameter considered in this study. Increases in temperature from February to July paralleled a decrease in body length and an increase in the percentage of spawning females. Mean female survival followed the variation of both temperature and chlorophyll concentration only between April and July. Temperature and chlorophyll concentration affected the reproductive parameters of T. longicornis differently. Female survival and body size were negatively correlated with temperature, while the highest chlorophyll concentrations were not always favourable for egg production. Therefore the quality of food should not be associated with chlorophyll quantity. Furthermore, the maximum values of egg production in this study are the highest recorded for T. longicornis. This study, conducted for the first time in the Eastern English Channel, showed high levels of productivity of T. longicornis despite a decrease of egg production during a Phaeocystis sp. dominated bloom in April.

A study of the stationary and the anomalous in the ocean surface chlorophyll distribution by satellite data

Variability of chlorophyll concentration in the ocean is one of the most important components of the primary production process on the planet. To preserve the biosphere and to make appropriate use of it, it is imperative to have a deep insight into the long-term dynamics of the primary production on the planet. To investigate the dynamics of chlorophyll concentration based on satellite data, the Institute of Biophysics (Russian Academy of Sciences, Siberian Branch) has developed a geoinformation system. It was used to detect the areas in the global ocean that are quasistationary in relation to seasonal dynamics of chlorophyll concentration. Areas such as these, found in the Indian Ocean, are described in this work. These areas form the basis for the analysis of long-term dynamics of chlorophyll concentration. In these quasistationary zones systematic monitoring of phytopigment concentration is conducted by space-borne and marine craft. The work presents long-term satellite-based data on the space distribution of anomalous deviations of chlorophyll concentration in the ocean. An anomaly criterion is proposed and maps of Pacific Ocean areas with a high probability of anomalies are presented.

Observation of chlorophyll fluorescence in west coast waters of Canada using the MODIS satellite sensor

The first observations of chlorophyll fluorescence from space for the west coast of Canada, using the U.S. moderate resolution imaging spectrometer (MODIS), show that the signals should provide a useful new tool for studying chlorophyll biomass and primary productivity. We compare MODIS fluorescence and sea-viewing wide field-of-view sensor (SeaWiFS) chlorophyll data, using a simple theoretical model of the expected variation of fluorescence emission with variations in chlorophyll concentration. The results show good agreement with the model and appear to allow separation of water masses according to fluorescence yield. As additional MODIS data come available it will be possible to study data for the full range of seasonal conditions. Additional data from the European medium-resolution imaging spectrometer (MERIS) sensor are available from 2002.

Phytoplankton, nutrients, and transparency in Danish coastal waters

We present a comparative analysis of 1400 data series of water chemistry (particularly nitrogen and phosphorus concentrations), phytoplankton biomass as chlorophylla (chla) concentrations, concentrations of suspended matter and Secchi depth transparency collected from the mid-1980s to the mid-1990s from 162 stations in 27 Danish fjords and coastal waters. The results demonstrate that Danish coastal waters were heavily eutrophied and had high particle concentrations and turbid waters. Median values were 5.1 μg chla 1−1, 10.0 mg DW 1−1 of suspended particles, and Secchi depth of 3.6 m. Chlorophyll concentration was strongly linked to the total-nitrogen concentration. The strength of this relationship increased from spring to summer as the concentration of total nitrogen declined. During summer, total nitrogen concentrations accounted for about 60% of the variability in chlorophyll concentrations among the different coastal systems. The relationship between chlorophyll and total phosphorus was more consistant over the year and correlations were much weaker than encountered for total nitrogen. Secchi depth could be predicted with good precision from measurements of chlorophyll and suspended matter. In a multiple stepwise regression model with In-transformed values the two variables accounted for most of the variability in water transparency for the different seasons and the period March–October as a whole (c. 80%). We were able to demonstrate a significant relationship between total nitrogen and Secchi depth, with important implications for management purposes.

Remote Estimation of the Chlorophyll Concentration of Living Trees Using Laser-induced Fluorescence Imaging Lidar

Monthly variation in chlorophyll concentration of living ginko tree leaves 65 m away from a system was remotely estimated by a laser-induced fluorescence imaging lidar. The combination of a pulsed laser and a short-time gated CCD using an image intensifier made it possible to monitor the weak fluorescence signal from the ginko tree leaves as an image. By applying the experimental idea that a ratio of intensity of the chlorophyll fluorescence at 740 nm to that at 685 nm showed a linear correlation to the chlorophyll concentration, the fluorescence image of the ginko tree obtained by the lidar was converted to the chlorophyll concentration distribution image.

Pumping of nutrients to ocean surface waters by the action of propagating planetary waves.

Primary productivity in the oceans is limited by the lack of nutrients in surface waters. These nutrients are mostly supplied from nutrient-rich subsurface waters through upwelling and vertical mixing, but in the ocean gyres these mechanisms do not fully account for the observed productivity. Recently, the upward pumping of nutrients, through the action of eddies, has been shown to account for the remainder of the primary productivity; however, these were regional studies which focused on mesoscale (100-km-scale) eddies. Here we analyse remotely sensed chlorophyll and sea-surface-height data collected over two years and show that 1,000-km-scale planetary waves, which propagate in a westward direction in the oceans, are associated with about 5 to 20% of the observed variability in chlorophyll concentration (after low-frequency and large-scale variations are removed from the data). Enhanced primary production is the likely explanation for this observation, and if that is the case, propagating disturbances introduce nutrients to surface waters on a global scale--similar to the nutrient pumping that occurs within distinct eddies.

Leaf optical properties in Venezuelan cloud forest trees.

Leaf optical properties and related leaf characteristics were compared for thirteen cloud forest tree species differing in successional status. Sun leaves were sampled for the eight pioneer species and sun and shade leaves were sampled for the five climax species. Sun leaves had a slightly higher absorptance than shade leaves, although differences were small. Sun leaves had a higher leaf mass per unit area (LMA) and a lower chlorophyll concentration per unit leaf mass, resulting in similar chlorophyll concentrations per unit leaf area and hence similar light harvesting capacities as shade leaves. However, shade leaves realized a higher efficiency of absorptance per unit leaf biomass than sun leaves. There were few differences in leaf characteristics of sun leaves between the climax and pioneer species. Absorptance values of cloud forest species were comparable with values reported for rain forest and more seasonal forest species. Intraspecific variation in leaf absorptance was largely the result of variation in LMA, whereas interspecific variation in leaf absorptance was largely a result of variation in chlorophyll concentration per unit leaf area.

Sensitivity analysis of a mathematical model of chlorophyll distribution in the tidal Keelung river

Large temporal and spatial variations in chlorophyll concentration found in estuarine and coastal waters have been attributed to a diverse set of physical, chemical and biological factors. The Keelung River has the largest tidal excursion and the most serious pollution problem among the three tributaries of the Tanshui River system in northern Taiwan. It receives extremely high anthropogenic nutrient loadings from municipal and industrial discharges with little or no treatment. The observed data show very high nutrient concentrations in the river, with total nitrogen of order of several milligrams per liter and total phosphorus of 1 mg/1. However, the summer chlorophyll ‘a’ concentrations are generally less than 10 μg/1. A time‐dependent, laterally averaged, two‐dimensional hydrodynamic and water quality model (HEM‐2DT) was applied to the tidal reach of the Tanshui River estuarine system to simulate the phytoplankton dynamics, nutrient cycling and dissolved oxygen distribution. The numerical model was calibrated and verified with observed chlorophyll ‘a’ and nutrient distributions in the Keelung River, and then used to investigate the various factors regulating chlorophyll ‘a’ distributions in that river. The sensitivity analyses include water‐column light extinction, nutrient reduction, freshwater discharge, boundary condition and effect of salinity distribution. The result reveals that light availability is the predominant limiting factor of phytoplankton growth, while nutrient concentrations are not limiting. The reduction of nutrient N and P loadings have no effect on chlorophyll ‘a’ concentration in the Keelung River.