Distribution Of Chlorophyll Concentration Research Articles

Variation of chlorophyll index and dry mass in Quercus robur L. trees from different provenances

In the comparative forest cultures of the "Plaiul Fagului” Scientific Reserve, an evaluation of the chlorophyll index and dry mass in the leaves of pedunculate oak descendants from the northern, central, and southern regions of the Republic of Moldova was carried out. The obtained data showed significant variations within trees in terms of minimum and maximum values, as well as the position of the median value relative to the mean in the distribution of the chlorophyll index in the investigated provenances. The analysis of the variation indicates significant differences in the distribution of the chlorophyll index of the leaves of trees originating from different ecological zones. Within this variation, two trends can be observed. The first trend refers to the fact that descendants from more distant areas (in the north and south) have a higher chlorophyll index than those from the central area (including local provenance). This difference due to the fact that descendants from ,,foreign” zones are exposed to different environmental conditions than optimal ones, which makes adaptation processes more pronounced compared to descendants from the central zone with similar conditions to the cultivation area. The second tendency consists of the uniformity in the response of different genotypes of non-locally provenance descendants from remote areas in the north and south, in relation to the specific environmental conditions of the common arboretum. This uniformity is indicated by lower coefficients of variation in the chlorophyll index of descendants from ,,foreign” zones compared to local provenance ones. Therefore, descendants of non-local provenance developed adaptation processes in new environmental conditions reflected by differences in the distribution of chlorophyll content. In descendants of northern and southern origin, these differences are lower than those characteristic of local provenance descendants. This view is supported by the fact that the dry mass rate of the leaves of local provenance descendants tends to be lower compared to those from the northern and southern parts of the Republic of Moldova.

Measurement of leaf chlorophyll content in Harumanis mango cultivated in a greenhouse using SPAD meter

The Soil and Vegetation Analysis Development (SPAD) value was correlated to the actual value of chlorophyll content in the Harumanis mango leaf using a developed regression model. Distribution of chlorophyll content in Harumanis mango leaves were mapped using Geospatial Analyst in the ArcGIS. Total chlorophyll content and SPAD value were well established with the polynomial regression model with coefficient of determination (R2) of 0.925. The results show that the measured SPAD value in the morning were comparable to those value made in the evening and the Harumanis leaves located in the middle of the greenhouse have 25–31.3% lower chlorophyll content compared to other parts of the greenhouse.

Fish Catch Results Related to Temperature and Chlorophil in Western Waters of Sumatera

The western waters of Sumatera are one of the waters that have the potential of coastal and ocean resources. Oceanographic factors that can be related to high productivity in waters are SST (Sea Surface Temperature) and the distribution of chlorophyll concentration. Sibolga waters are geographically quite strategic, because they are located in the Indian Ocean, most of the catch is landed at the Sibolga Nusantara Fisheries Port. This Study aims to understand the trend of fluctuations in fish catches in the The Waters of Western Sumatera, to examine the effect of chlorophyll on fish catches in the waters of West Sumatera. Sea surface temperature and monthly chlorophyll-a concentrations were obtained from the result of the Aqua Modis months in 2021. Monthly data and data on fishing results were obtained from the Sibolga Nusantara Fisheries Port. The composition of catches in the western waters of Sumatera which landed at PPN Sibolga in 2021there three dominant fish species, namely Cakalang (Katsuwonis Pelamis) 11.655.768 Kg, Layang (Decapterus Sp) 4.589.147 (19,95%), Tembang (Sardinella sp) 2.421.523 (10,53%), the variation of fish catch per unit (CPUE) ;anded at PPN 2021. The Highest occurred in may at 3.809 kg/trip and the lowest occurred in November 1.521,58 kg/trip and the average monthly CPUE in 2021 was 5.105,88kg/trip. Monthly variations of sea surface temperature and chlorophyll-a in the waters of for 12 months (2021) the lowest temperature occurred in August, namely 26,88 0C while the highest temperature in February was 30,92 0C, the highest consentration was in May of 1,56 mg/m3 while the lowest occurred in March at 0,15 mg/m3.

How do El Niño Southern Oscillation (ENSO) Events Impact Fish Catch in Sarawak Water?

The response of chlorophyll to climate variability plays an important role in regulating the regional marine ecological environment and carbon cycle. This study focuses on the impact of changes in chlorophyll on the catches of deep-water fish and offshore fish. The chlorophyll factors from satellite image MODIS were analysed during La Niña in 2008/2011 and El Niño in 2015/2016. Remote sensing reflectance’s 443 nanometres and 555 nanometres were utilized to examine the bias of the chlorophyll concentration, Thus the higher phytoplankton absorption coefficient at 443, and backscattering coefficient for dissolved and detrital material stated the more phytoplankton biomass and higher suspended sediment concentration. The results found that the fish catch during El Niño is higher at 295572 metric tons compared to during La Niña which is 255783 metric tons. The El Niño event was found to have experienced an increase in catch of 29789 metric tons. This is due to the influence of the change in the mean value of the concentration in the study area of 0.31 mg-3 during La Niña compared to during El Niño 0.4 m mg-3. A decrease in the average value concentration of -0.09 mg-3 resulted in a decrease in the number of catches. In addition, the maximum value of chlorophyll concentration was also found to be high during El Niño which is 22 m mg-3 compared to during La Niña which is 18 m mg-3. The high distribution of chlorophyll-a is in the coastal areas of Sarawak, which explains why the coastal fish catches are higher than in the deep sea. It is concluded that the distribution of chlorophyll concentration is different during the occurrence of ENSO. This may result in different fishing rates in the study area. Remote sensing technology successfully explains why fish catches during El Niño are higher than during La Niña based on different chlorophyll dispersions. The provision of information in this space is very important to fishermen to reduce operating costs.

Monitoring the Vertical Distribution of Maize Canopy Chlorophyll Content Based on Multi-Angular Spectral Data

Remote sensing approaches have several advantages over traditional methods in determining information on physical and chemical parameters, including timely data acquisition, low costs, and wide coverage. Thus, remote sensing is widely used in crop growth monitoring. Unlike vertical observations, multi-angular remote sensing technology can obtain the vertical distribution information of the central and lower leaves of a crop. Furthermore, applications of remote sensing on the vertical distribution of maize canopy components is complicated, and related research is limited. In the current paper, we employed multi-angular spectral data, measured by a self-designed multi-angular observation instrument at view zenith angles (VZAs) of 0°, 10°, 20°, 30°, 40°, 50°, and 60°, to explore the monitoring strategy and monitoring precision of the vertical distribution of chlorophyll content in the maize canopy. This was then used to determine the optimal monitoring method for the chlorophyll content (soil and plant analyzer development (SPAD) value) of each layer. The correlation between SPAD value and chlorophyll sensitivity indices at different growth stages was used as the basis for screening indices and VZAs. The correlation between the selected EPI (eucalyptus pigment index) and REIP (red edge inflection point) indices and chlorophyll content indicated view zenith angles (VZAs) of 0°, 30°, and 40° as optimal for the early growth stage monitoring of chlorophyll content in the 1st, 2nd, and 3rd layers, respectively. These values were associated with RMSEs of 4.14, 1.71, and 1.11 for EPI, respectively; and 4.61, 2.31, and 1.00 for REIP, respectively. In addition, a VZA of 50° was selected to monitor the chlorophyll content of the 1st, 2nd, 3rd, and 4th layers at the late growth stage, with RMSE values of 2.97, 3.50, 2.80, and 4.80 for EPI, respectively; and 3.16, 5.02, 4.55, and 7.85 for REIP, respectively. The results demonstrated the ability of canopy multi-angular spectral reflectance to accurately estimate the maize canopy chlorophyll content vertical distribution, with the VZAs of different vertical layers varying between the early and late growth stages.

Influence of Storm Events on Chlorophyll Distribution Along the Oligotrophic Continental Shelf Off South-Western Australia

The role of storm events in controlling chlorophyll distribution along the oligotrophic Rottnest continental shelf is examined data collected by autonomous ocean gliders combined with meteorological data. Spatial and temporal distribution of chlorophyll concentrations were obtained from a repeated transect across the shallow continental shelf that revealed complex relationships among wind events (e.g. differences in wind speed and direction) and chlorophyll concentrations. Data indicated that the water column responded rapidly to changes in wind speeds alternating between stratification, de-stratification and vice-versa over 1-3 days. Under low wind conditions (wind speeds 15 ms-1) higher chlorophyll values were present throughout the vertically mixed water column. Maximum chlorophyll concentrations, more than double that due to climatology, were observed 1-3 days after the passage of storms subsequent to sediment re-suspension. Storm events, with an onshore component, promoted downwelling, the water column retained vertical stratification, and DSWC was present across the shelf. Here, DSWC intensified with higher chlorophyll in the cascaded water extending further offshore. It is concluded that wind speed and direction are the dominant parameters controlling the distribution of chlorophyll particularly during storm events.

Nondestructive diagnostics of magnesium deficiency based on distribution features of chlorophyll concentrations map on cucumber leaf

A new and nondestructive method for diagnosing magnesium (Mg) deficiency based on chlorophyll concentration distribution features of cucumber leaves was proposed. Mg deficient cucumber plants and Control plants were grown under non-soil conditions with special nutrient supply. Cucumber leaves were employed to collect hyperspectral images using a visible and near infrared (VIS/NIR) hyperspectral imaging system (400–900 nm) and determine reference chlorophyll concentrations using high performance liquid chromatography (HPLC). An optimal chlorophyll concentration calibration model (Rp = 0.9087) was constructed and used to detect chlorophyll distribution maps of Mg deficient leaves and Control leaves. Results shown that chlorophyll content distributed more unevenly on Mg deficient leaves than Control leaves. The Standard Deviation (SD) value of the chlorophyll content at all the pixels on a chlorophyll distribution map was calculated for Mg deficient diagnostics. An Mg deficiency diagnostics model with satisfied performance (diagnostic rate 93.33%) was obtained. The result indicated the SD value of chlorophyll concentrations on the whole cucumber leaf could be employed to diagnose Mg deficiency nondestructively.

Improved correction for non-photochemical quenching of in situ chlorophyll fluorescence based on a synchronous irradiance profile.

In situ chlorophyll fluorometers have been used to quantify the distribution of chlorophyll concentration in natural waters for decades. However, chlorophyll fluorescence is depressed during daylight hours due to non-photochemical quenching (NPQ). Corrections attempted to date have provided improvement but still remain unsatisfactory, often over-estimating the expected value. In this study, we examine the relationship between NPQ and instantaneous Photosynthetically Active Radiation (iPAR) using field data from BGC-Argo floats equipped with Chlorophyll-a fluorometers and radiometers. This analysis leads to an improved NPQ correction that incorporates both iPAR and mixed layer depth (MLD) and is validated against data collected at sunrise or sunset. The optimal NPQ light threshold is found to be iPAR = 15 μmol quanta m-2 s-1, and the proposed methods based on such a light threshold correct the NPQ effect more accurately than others, except in "shallow-mixing" waters (NPQ light threshold depth deeper than MLD). For these waters, an empirical-relationship-based method is proposed for improvement of NPQ correction using an iPAR profile. It is therefore recommended that, for optimal NPQ corrections, profiling floats measuring chlorophyll fluorescence in daytime be equipped with iPAR radiometers.

SPATIAL-TEMPORAL DISTRIBUTION OF CHLOROPHYLL-A IN SOUTHERN PART OF THE MAKASSAR STRAIT

Surface chlorophyll-a (Chl-a) distribution have been analyzed with seasonal variation during southeast monsoon in southern part of Makassar Strait and Flores Sea. Satellite data of Landsat-8 is applied to this study to formulate the distribution of chlorophyll concentration during monsoonal wind period. The distribution of chlorophyll concentration was normally peaked condition in August during southeast monsoon. Satellite data showed that a slowdown in the rise of the distribution of chlorophyll in September with a lower concentration than normal is likely due to a weakening the strength of southeast trade winds during June – July – August 2016. Further analysis shows that the southern part of the Makassar strait is likely occurrence of upwelling characterized by increase in surface chlorophyll concentrations were identified as the potential area of fishing ground.

Causal mechanisms of the deep chlorophyll maximum in Lake Superior: A numerical modeling investigation

The deep chlorophyll maximum (DCM) is a near ubiquitous feature in Lake Superior during the summer stratified season. Previous studies have elucidated observable characteristics of the DCM in Lake Superior but the physical and biological mechanisms controlling the creation and maintenance of the DCM remained unclear. We use a three-dimensional hydrodynamic model of Lake Superior coupled to an ecological model to perform sensitivity runs exploring the influence of photoadaptation, photoinhibition, zooplankton grazing, and phytoplankton sinking on the vertical distribution of chlorophyll in the water column. The role of a nutricline in determining the presence and nature of the DCM is also explored. The presence of the DCM is dependent upon the presence of thermal stratification in the model. The sensitivity runs reveal that photoadaptation plays a primary role in determining the depth of the DCM in the model while zooplankton grazing and phytoplankton sinking affected the magnitude but not the presence or depth of the DCM. Photoinhibition showed negligible effects on chlorophyll concentration distribution. The presence of a nutricline in the model is also a necessary condition for the formation of the DCM and it influences both the depth and magnitude of the DCM.

Nondestructive diagnostics of nitrogen deficiency by cucumber leaf chlorophyll distribution map based on near infrared hyperspectral imaging

Chlorophyll concentration distribution map of cucumber leaf given by near infrared hyperspectral imaging was used to determine nitrogen (N) deficiency. 120 fresh leaves picked from N deficient and control plants were used for hyperspectral image collection and chlorophyll concentration determination. Firstly, after hyperspectral image acquisition and pre-processing, the average spectra obtained from the region of interest (ROI) in leaf hyperspectral images were extracted. Secondly, principal component analysis (PCA) was performed on the average spectrum to reduce the dimension along the wavelength axis. Thirdly, multi-linear regression (MLR) was used to build calibration models relating the spectra and chlorophyll concentration which determined by high performance liquid chromatography (HPLC). The calibration models were applied to an independent prediction set for validation. Chlorophyll concentration was reasonably well predicted with a high correlation (R=0.8712). Finally, the calibration model was used to predict the chlorophyll concentration of each pixel in the hyperspectral image. Therefore, distribution maps of chlorophyll concentration on the N deficient and control cucumber leaves were obtained. Obvious differences could be directly observed from the chlorophyll distribution maps between N deficient leaves and control leaves. Depend on the maps, the mean value of chlorophyll concentration were calculated at lower nodes for N deficiency diagnostics. 12mg/g was defined as a threshold for the lower nodes leaf in diagnostics of N deficiency. Our results indicate that hyperspectral imaging exhibits considerable promise for nondestructive diagnostics of N deficiency in cucumber plant.

Chlorophyll variability in the northeastern Gulf of Mexico

Changes in chlorophyll concentration distribution in surface waters of the northeastern Gulf of Mexico NEGOM were examined using satellite and in situ data collected between November 1997 and Augus...

Chlorophyll variability in the northeastern Gulf of Mexico

Changes in chlorophyll concentration distribution in surface waters of the northeastern Gulf of Mexico (NEGOM) were examined using satellite and in situ data collected between November 1997 and August 2000. The patterns of chlorophyll distribution derived from in situ data consistently matched the satellite observations, even though the satellite-derived concentrations in coastal and offshore waters influenced by rivers were overestimated by the standard satellite data processing algorithms. River discharge and wind-driven upwelling were the major factors influencing surface chlorophyll-a variability for inshore regions. High in situ chlorophyll-a concentrations (≥1 mg m−3) occurred inshore and particularly near major river mouths during the summer seasons of 1998, 1999 and 2000. Plumes of Mississippi River water extended offshore to the southeast of the delta over distances >500 km from the river delta for maximum periods of 14 weeks between May and September every year and could reach the Florida Keys in certain years. The offshore transport of the plume was initiated by eastward or southeastward winds and then by separate anticyclonic eddies located southeast of the Mississippi delta and nearby shelf every year. Chlorophyll concentrations during the winter to spring transition in 1998 off Escambia, Choctawhatchee, Apalachicola and Suwannee Rivers and off Tampa Bay were up to 4 times higher than during the same periods in 1999 and 2000. This was related to higher freshwater discharge during the 1997–1998 winter–spring transition, coinciding with an El Niño–Southern Oscillation event, and to the unusually strong upwelling observed along the coast in spring 1998.

Estimation of vertical distribution of chlorophyll concentration by bi-directional canopy reflectance spectra in winter wheat

An effective technique to measure foliage chlorophyll concentration (Chl) at a large scale and within a short time could be a powerful tool to determine fertilization amount for crop management. The objective of this study was to investigate the inversion of foliage Chl vertical-layer distribution by bi-directional reflectance difference function (BRDF) data, so as to provide a theoretical basis for monitoring the growth and development of winter wheat and for providing guidance on the application of fertilizer. Remote sensing could provide a powerful tool for large-area estimation of Chl. Because of the vertical distribution of leaves in a wheat stem, Chl vertical distribution characteristics show an obvious decreasing trend from the top of the canopy to the ground surface. The ratio of transformed chlorophyll absorption reflectance index (TCARI) to optimized soil adjusted vegetation index (OSAVI) was called the canopy chlorophyll inversion index (CCII) in this study. The value of CCII at nadir, ±20 and ±30°, at nadir, ±30 and ±40°, and at nadir, ±50 and ±60° view angles were selected and assembled as bottom-layer Chl inversion index (BLCI), middle-layer Chl inversion index (MLCI), and upper-layer Chl inversion index (ULCI), respectively, for the inversion of Chl at the vertical bottom layer, middle layer, and upper layer. The root mean squared error (RMSE) between BLCI-, MLCI-, and ULCI-derived and laboratory-measured Chl were 0.7841, 0.9426, and 1.7398, respectively. The vertical foliage Chl inversion could be used to monitor the crop growth status and to guide fertilizer and irrigation management. The results suggested that vegetation indices derived from bi-directional reflectance spectra (e.g., BLCI, ULCI, and MLCI) were satisfactory for inversion of the Chl vertical distribution.

STUDY OF OCEAN PRIMARY PRODUCTIVITY USING OCEAN COLOR DATA AROUND JAPAN

Ocean primary production is an important factor for determining the ocean's role in global carbon cycle. In recent years, much more chlorophyll-a concentration data in the euphotic layer were derived from the satellite ocean color sensors. The primary productivity algorithms have been proposed based on satellite chlorophyll measurements (Piatt, 1988; Morel, 1991) and other environmental parameters such as sea surface temperature or mixed layer depth (Behrenfeld and Falkowski, 1997; Esaias, 1996; Asanuma, 2002). In order to estimate integrated primary productivity in the whole water column, the vertical distribution of chlorophyll concentration below the sea surface should be reconstructed based on satellite data. In this paper, the vertical profile data of chlorophyll-a (Chl-a) measured around Japan Islands from 1974 to 1994 were reanalyzed based on the shifted-Gaussian shape proposed by Piatt et al (1988). Using this statistical model (neural network) and the photosynthesis irradiance parameters from Asanuma (2002), the distribution of primary productivity and its seasonal variation around Japan islands were estimated from SeaWiFS data, and the results were compared with in situ data and the other two models estimated from VGPM and mixed layer depth model. Keywords: ocean color, primary productivity, chlorophyll profile, artificial neural network

Comparison of global chlorophyll concentrations using MODIS data

Chlorophyll concentrations derived from satellite borne ocean color sensors data provide an idea of the distribution of phytoplanktons across the oceans which help us in understanding the spatial and temporal dynamics of phytoplanktons. The changes in the patterns of distribution and abundance of the planktons have significant impact on the entire ecosystem and play a key role in the global carbon cycle. In this paper, we have analyzed annual and seasonal chlorophyll concentrations retrieved from MODIS data for the periods March 2000–October 2003, which reveal the spatial and seasonal distribution of chlorophyll concentrations across the global oceans. Chlorophyll concentrations anomaly indicate that chlorophyll concentrations in almost all ocean regions responded similarly.

Control of phytoplankton biomass by dilution and mixed layer depth in the western Weddell-Scotia Confluence

Hydrographic, nutrient and trace metal (iron, manganese, and aluminum) concentration data, collected as part of a 2-ship survey during austral summer 2004, were used to examine the influ- ence of upwelling and horizontal mixing on phytoplankton biomass in the region of Elephant Island and South Shetland Islands, Antarctica. Temperature/salinity property analysis and changes in trace metal and nutrient concentrations show that horizontal mixing of shelf waters, not upwelling from depth, is correlated with phytoplankton biomass in the upper mixed layer (UML). The interaction between changing UML depth and nutrient and trace metal concentrations in the UML results in a unimodal distribution of phytoplankton biomass centered at intermediate surface salinities of ~34. Principal component (PC) analysis of hydrographic and chemical observations resolved 3 compo- nents that accounted for 99% of the variability in nutrient and trace metal concentrations. The first PC accounted for a conservative loss of nutrients through dilution across a latitudinal salinity gradi- ent. The second and third PCs separated mixed layer depth and nutrient consumption. Although these 2 PCs accounted for just 20% of the variability in the data matrix, they accounted for 65% of the variability in mean phytoplankton biomass, and recreated the unimodal distribution of chlorophyll concentration when modeled across a salinity gradient. We propose that the distribution of phyto- plankton biomass is structured by the horizontal mixing of nutrient rich waters, derived from Weddell Sea Shelf Waters, with Antarctic Surface Water that enhances stratification and shoaling of the UML.

Study on the correlation between chlorophyll maximum and remote sensing data

Based on the in situ optical measurements in the Bohai Sea of China, which belongs to a typical case-2 water area, we studied the characteristics of DCM (deep chlorophyll maximum) such as its spatial distribution, vertical profile, etc. We found that when the depth of the chlorophyll maximum is comparatively small, even in turbid coastal water regions, there is always a good correlation between the concentrations of chlorophyll maximum and the satellite-received signals in blue-green spectral bands; the correlation is even better than that between the surface chlorophyll concentrations and the satellite-received signals. The strong correlation existing even in turbid coastal water regions indicates that an ocean color model to retrieve the concentration of DCM can be constructed for coastal waters if a comprehensive knowledge of the vertical distribution of chlorophyll concentration in the Bohai Sea of China is available.

Spatial and temporal variability of phytoplankton in the Gulf of Cádiz through remote sensing images

The temporal and spatial distribution of chlorophyll concentration in the Gulf of Cadiz (SW Spain) was analysed between 1998 and 2002 by remote sensing data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Climatological and monthly averages showed the presence of more productive waters in the inner shelf of the basin, especially during spring and fall, according to the phytoplankton blooms observed. This pattern was further confirmed by the modes obtained with an Empirical Orthogonal Function (EOF) decomposition of weekly chlorophyll composite images performed for the whole period. The first EOF mode explained 20% of the variability and corresponded to the chlorophyll seasonality in the basin. The second EOF mode accounted for 10% of the variability and distinguished several regions with different oceanographic features in the area. Five zones could be identified among which, a coastal zone between Huelva and Cadiz, was found to show the highest chlorophyll concentration values. Local zonal winds, categorized as westerlies and easterlies, were coupled with differences in biological production. The former induced an increase in chlorophyll concentration whereas the latter caused a decrease in phytoplankton biomass. Rainfall and river discharge also affected markedly the chlorophyll concentration.

Estimation of ocean primary productivity and its spatio-temporal variation mechanism for East China Sea based on VGPM model

According to calculation results of ocean chlorophyll concentration based on SeaWiFS data by SeaBAM model and synchronous ship-measured data, this research set up an improved model for Case I and Case II water bodies respectively. The monthly chlorophyll distribution in the East China Sea in 1998 was obtained from this improved model on calculation results of SeaBAM. The euphotic depth distribution in 1998 in the East China Sea is calculated by using remote sensing data of K490 from SeaWiFS according to the relation between the euphotic depth and the oceanic diffuse attenuation coefficient. With data of ocean chlorophyll concentration, euphotic depth, ocean surface photosynthetic available radiation (PAR), daily photoperiod and optimal rate of daily carbon fixation within a water column, the monthly and annual primary productivity spatio-temporal distributions in the East China Sea in 1998 were obtained based on VGPM model. Based on analysis of those distributions, the conclusion can be drawn that there is a clear bimodality character of primary productivity in the monthly distribution in the East China Sea. In detail, the monthly distribution of primary productivity stays the lowest level in winter and rises rapidly to the peak in spring. It gets down a little in summer, and gets up a little in autumn. The daily average of primary productivity in the whole East China Sea is 560.03 mg/m2/d, which is far higher than the average of subtropical ocean areas. The annual average of primary productivity is 236.95 g/m2/a. The research on the seasonal variety mechanism of primary productivity shows that several factors that affect the spatio-temporal distribution may include the chlorophyll concentration distribution, temperature condition, the Yangtze River diluted water variety, the euphotic depth, ocean current variety, etc. But the main influencing factors may be different in each local sea area.