Differences In Chlorophyll Concentrations Research Articles

Comparing the atmospheric and ocean characteristics associated with two distinctly intensified pre‐monsoon tropical cyclones over the Bay of Bengal

AbstractTropical cyclone (TC) Amphan is analyzed in terms of the various factors that governed the intensification process associated with it and compared with Fani. Furthermore, the TC radial characteristics and ocean productivity are examined. Notably, both TCs formed in the Bay of Bengal during the pre‐monsoon seasons of 2020 and 2019, respectively. For this study, both ocean and atmospheric parameters from various sources including global analyses, satellite observations, and outputs from Model for Prediction Across Scales‐Atmosphere (MPAS‐A) and Advanced Research Weather Research and Forecasting (WRF‐ARW), are considered. The results indicate a gradual decrease in vertical wind shear during Fani. In the case of Amphan, the increase in mid‐tropospheric relative humidity values is found to be substantial. The sea surface cooling after the passage of Amphan was higher than in the case of Fani. The higher sea surface temperature in the Amphan case corresponds to the lower aerosol loading (partly because of lockdown measures) than that of Fani in the pre‐cyclone phase. And the decrease (increase) in aerosol loading coincides with an increase (decrease) in the direct radiative forcing at the ocean surface. The Madden–Julian Oscillation played a greater role in the cyclogenesis of Fani, but Kelvin waves offered a major support in the case of Amphan. The warmer sea surface, higher tropical cyclone heat potential, and conducive ocean and atmospheric setting together supported the further intensification of Amphan to the supercyclone stage. The difference in chlorophyll concentration showed a significant variation, with higher positive values seen in the case of Amphan implicating greater vertical mixing. The numerical modeling effort indicated superior performance of MPAS‐A compared to WRF‐ARW in simulating the radial parameters of the TCs.

Photosynthetic Responses of Anthurium × 'Red' under Different Light Conditions.

Light is an essential energy source for plant photosynthesis, although it can also be a stress-causing element. Therefore, the current research was aimed to compare photosynthetic responses of Anthurium × ‘Red’ leaves at different positions (bottom old leaf, 1; center mature leaf, 2; top expanded leaf, 3) established under three photosynthetic photon flux densities (PPFDs): 550 μmol·m−2·s−1 as high (H), 350 μmol·m−2·s−1 as medium (M), and 255 μmol·m−2·s−1 as low (L). After six months, all the replicates were relocated to interior rooms with a PPFD of 30 μmol·m−2·s−1. There were no significant differences in chlorophyll concentration of the old leaf among treatments, before (Day 0) and after shifting the plants to interior rooms (Day 30). The total chlorophyll concentrations of the mature and top leaves increased significantly. In greenhouse conditions, H and M treatments did not show any significant change for net photosynthetic rate (Pn) at various leaf positions. However, M2 exhibited an improved Pn in the interior conditions. Plants grown under M treatment were greener and had bigger leaves compared to other treatments. Our study reveals that Anthurium × ‘Red’ photosynthesis responses to different light conditions varied distinctly. However, M treatment can keep the plants looking green by accumulating enough energy for indoor conditions, and middle and lower leaves may be triggered to restore photosynthetic activity under low light or indoor conditions.

Spatially heterogeneous trends in nearshore and offshore chlorophyll a concentrations in lakes Michigan and Huron (1998–2013)

Abstract Nutrient abatement programmes have been successfully implemented around the globe to reduce nutrient loading into aquatic ecosystems. Concurrently, the worldwide spread of invasive filter feeders, such as dreissenid mussels, may alter nutrient dynamics in invaded systems by sequestering nutrients away from pelagic zones and reducing primary production in offshore areas. Such is the case in the Laurentian Great Lakes of North America, where decades of nutrient abatement and the establishment of dreissenid mussels have seemingly resulted in more oligotrophic conditions and altered spatial patterns of nutrient availability and primary production. Recent studies have focused on whole lake trends in primary production despite spatial differences in tributary inputs, bathymetry, and other environmental conditions that can affect primary production in nearshore areas. Thus, we hypothesised that trends in nearshore chlorophyll concentrations in different areas may diverge in a manner consistent with spatial differences in nutrient input. To evaluate these differences in surface chlorophyll responses, we assessed temporal trends in four different areas of Lake Michigan and three different areas of Lake Huron. We hypothesised that in lakes Huron and Michigan, nearshore zones have experienced slower declines of chlorophyll concentrations relative to offshore zones. To assess this hypothesis, we estimated temporal trends of surface water chlorophyll concentrations (a proxy for primary production) from satellite imagery from 1998 to 2013. We calculated average surface chlorophyll concentrations for 10‐m depth intervals ranging from the shore (0–10 m) to offshore (>90 m) during representative months of May, July, and September. We then analysed these data to determine if long‐term trends in surface chlorophyll varied by season, proximity to the shoreline, and water depth. The rates of annual change in chlorophyll concentrations in nearshore areas were markedly different to offshore trends in both lakes. Chlorophyll concentrations declined overtime in offshore areas, but nearshore chlorophyll concentrations were either stable (in May) or increased (in July and September) throughout the time series. Differences in chlorophyll concentrations among areas were prominent in Lake Michigan. While differences between the northern and southern basin have been previously documented, trends in chlorophyll concentrations also differed between the eastern and western sides of Lake Michigan. Despite similar bathymetry and geographic features to Lake Michigan, regional trends were not observed in Lake Huron. The results of this study are generally consistent with the nearshore shunt hypothesis, which predicts that dreissenid filtering, nutrient re‐suspension, and continued nutrient loading from tributaries can cause an increase in primary production in nearshore areas during periods of offshore oligotrophication. Thus, the localised effects of nutrient abatement programmes in a given lake will be influenced by complex interactions between lake bathymetry and the presence of non‐native filter feeding organisms.

Growth and photosynthetic performance of Chlamydopodium fusiforme cells cultivated in BG11 and Bristol media

Nitrogen is an essential nutrient for all life forms and its availability is periodically limited in marine and freshwater ecosystems. To optimize the growth of the freshwater microalga Chlamydopodium fusiforme and to investigate the cell acclimation process to different amounts of nitrogen, we grew cells in Bristol and BG11, under fixed conditions of 10 h:14 h light/dark cycle. Cultures grown in BG11 exhibited higher biomass accumulation, reaching a cell dry weight of 1.94 ± 0.1 g L−1, while in Bristol it reached 1.58 ± 0.1 g L−1. In cells grown in BG11, chlorophyll content increased continuously up to 79.6 mg L−1 (9th day), while in Bristol it was much lower (29.5 mg L−1). This fact caused a strong difference in their spectrally averaged optical cross-section normalized to chlorophyll a (a*), and consequently in their photosynthetic performance (oxygen evolution and electron transport rates). Carotenoid content followed a similar pattern. It was interesting to note that despite this great difference in chlorophyll concentration, both photosynthesis rate and cell dry weight were not affected proportionally. The chlorophyll a fluorescence measurements indicated a stable effective quantum yield of photosystem II in both culture conditions. During the dark phase of the cycle we observed in both cultures a remarkable reduction of both electron transfer and photosynthesis rates, while maximum quantum yield of PSII remained stable (0.74 ± 0.01). This indicated that the reduction in both photosynthesis rate and maximum electron transport rate (ETRmax) observed during the dark phase were not due to damage of PSII reaction centers but rather to reduced flow of electron subsequent to PSII. Recovery of the fully photosynthetic capacity required about 1 h of illumination.

Spatial variability in factors that control the sinking flux of organic and inorganic particles in the Cariaco Basin: a vision from space

ABSTRACTThe Cariaco Basin, located on the continental margin of the south-eastern Caribbean Sea, has been a site of extensive oceanographic research since the early 1950s. Here we examined the seasonal and spatial variability in satellite wind, sea surface temperature (SST), surface chlorophyll (CHL), and primary production (PP) within the Cariaco Basin (1994–2009). This variability has implications in modulating the vertical flux of particulate material to the bottom of the basin. While cross-shore Ekman Transport was positive (upwelling inducing) year-round, it showed 20–60% higher values (stronger upwelling) in the eastern sub-basin, compared to the western sub-basin 1.35–2.77 m2 s−1 and 1.06–1.73 m2 s−1, respectively; p < 0.01). This translated into differences in CHL concentration and PP rates between the eastern and western Cariaco sub-basins. Long-term seasonal means of SST, CHL, and PP showed significant inter-basin differences (p < 0.01) between December and July; during that period the eastern basin was cooler (24.86 ± 1.03°C vs. 25.56 ± 0.80°C, p < 0.01), with higher CHL (0.50 mg m−3 vs. 0.35 mg m−3; p < 0.01) and PP (1763 ± 994 vs. 782 ± 129 mg C m−2 day−1, p < 0.01) than the western sub-basin. The eastern Cariaco sub-basin had larger seasonal amplitude and variability in oceanographic characteristics than the western sub-basin, while the western sub-basin had slightly higher and more variable seasonal riverine run-off inputs. These differences have implications for the interpretation of the paleoclimate sediment record stored in different sectors of the Cariaco Basin.

An Assesesment of Leaf Chlorophyll Concentration of Afforestation Tree Species in South-Eastern, Nigeria

Abstract Leaf chlorophyll content provides valuable information about physiological status of plants. However, fewer studies have investigated the difference in chlorophyll concentration in leaves of tropical afforestation tree species. Therefore, this study examines the difference in foliar chlorophyll contents of six tropical afforestation tree species namely: Tectona grandis, Pentaclethra macrophylla, Piptademiastrum africanum, Azadirachta indica, Brachystegia eurycoma and Gmelina arborea found in the relict forest in Umudike, South east, Nigeria. A single factor experiment in a completely randomised design in three replicates was employed to analyse the rate of leaf chlorophyll contents. Fisher’s least significant different was used to test for significance in mean difference in foliar chlorophyll contents between tree species at 95% confidence interval using analysis of variance. The results of this study showed a significant difference in foliar chlorophyll concentration between the tree species with Tectona grandis having a higher chlorophyll concentration than other trees this could be as a result of its higher vegetative activity which increases its primary productivity followed by Pentaclethra macrophyllawhile Azadirachta indica having least the chlorophyll concentration. The study further revealed that other indigenous tree species like Piptademiastrum africanum and Brachystegia eurycoma have higher chlorophyll concentration. Further studies should be carry out to examine factors that have contributed informed the differences in the chlorophyll concentration of these trees species, thus this would broaden the understanding of their physiological status and equally encourage there conservation.Key Words: physiological status, chlorophyll concentration, tree species, tree foliar, environmental stress, productivity

INHERITANCE PATTERN OF YELLOW FOLIAGE COLOUR AND ACTIVITIES OF TRANSPOSABLE ELEMENT IN COWPEA Vigna unguiculata (L.) Walp

Foliage colour may affect the photosynthetic activities of a plant and consequently yield. Differences in the green foliage colour of plants often reflect differences in chlorophyll concentration of the leaves. This study investigated the inheritance pattern of a yellow foliage mutant in cowpea. Seeds of a nuclear yellow foliage mutant and three green foliage cowpea lines were planted in plastic buckets filled with garden soil on the roof top garden of Department of crop Protection and Environmental Biology, University of Ibadan, Nigeria and crossed to produce six generations per cross comprising parents, F 1 , F 2 and BC. The various generations were and on the field at the Teaching and Research Farm of the University of Ibadan, Nigeria and data were collected on phenotypic traits. The nuclear yellow foliage mutant segregated in the ratio 3green:1yellow, thus indicating that the trait was controlled by monogenic recessive gene. Some F 2 and BC plants of the yellow foliage mutant exhibited variegation for leaf colour indicating gene instability resulting from the action of transposable element. The frequencies of reversion from the yellow to green of F 3 progenies vary widely within and between progeny rows. Of a total of 309 individual plants that were scored, 55% were variegated, 23% were green while 22% exhibited the yellow phenotype. The gene symbol yfc-3 was assigned to the recessive condition, while yfc-3 un was assigned to the unstable allele of yellow foliage.

A methodology to develop algorithms that predict nitrogen fertilizer needs in maize based on chlorophyll measurements: a case study in Central Mexico

SUMMARYIdentifying and applying the optimum fertilizer nitrogen (N) rate is a permanent challenge for farmers. Prediction of fertilizer N requirement, based on crop chlorophyll measurements (CMs), relies on a strong relationship between fertilizer N supply and leaf chlorophyll concentration at a given crop growth stage. A methodological approach is described, aiming to develop an algorithm that uses CM inputs to derive the economically optimum fertilizer N rate for top-dressing, without using a reference plot for data normalization. The method was tested on maize (Zea mays L. cvar Jabali) at experimental and farmer sites in the central (‘Bajío’) region of Mexico over 3 years (2010–12). Increasing fertilizer N supply at planting significantly influenced chlorophyll concentration at the seventh unfolded maize leaf stage (GS 17 on the Zadoks scale). Maize grain yields increased with increasing total fertilizer N supply and fitted quadratic models, which allowed economically optimum fertilizer N rates (Nopt) to be calculated. The Nopt ranged from 160 to 300 kg N/ha and corresponding grain yields ranged from 7·7 to 14 t/ha. Grouped data analysis (sites–years) confirmed a highly significant relationship between the Nopt and the chlorophyll concentration at GS 17, which could be described by a linear model: Nopt = 513·3–0·58 × CM. This model predicted the top-dressing Nopt within a fertilizer N management regime adapted to local maize cropping systems and led to similar grain yields across test sites compared with the same parameters calculated based on grain yield response trials. The current approach is variety-specific, so development of so-called correction factors accounting for variety-related differences in chlorophyll concentration is described. The results demonstrated the feasibility of the proposed algorithms to support decision-making on the optimum fertilizer N rate to apply in maize production systems with one top-dressing application.

Impact of improved light calculations on predicted phytoplankton growth and heating in an idealized upwelling‐downwelling channel geometry

AbstractOcean ecosystem models require accurate calculations of both hydrodynamics and biology; those calculations in turn require accurate calculation of in‐water irradiance. Ecosystem models now achieve great accuracy in their hydrodynamical predictions, and the biological modules are becoming correspondingly sophisticated. The optical calculations are however often oversimplified, to the possible detriment of the physical and biological predictions. We used a recently developed, extremely fast radiative transfer code, EcoLight‐S, to study differences in ecosystem and thermal development in an idealized upwelling‐downwelling system when simple versus accurate irradiance calculations are used. The use of accurate irradiances gave up to 57% differences in chlorophyll concentrations after two weeks of simulated time, compared to predictions based on irradiances obtained using a simple exponential attenuation formula. Accurate irradiance calculations increased sea surface temperatures and decreased temperatures at depth, leading to increased stratification. Use of EcoLight‐S couples the physical and biological calculations so that biology feeds back to physics, and vice versa. EcoLight‐S outputs ancillary quantities such as remote sensing reflectance and in‐water spectral irradiance, which can be used to validate ecosystem predictions using remotely sensed ocean color imagery or optical measurements from buoys or gliders, without the need to convert such measurements to chlorophyll values. After optimization, the ecosystem model total run times with EcoLight‐S were less than 20% more than for the analytical irradiance models. We also found that the use of 24 h average irradiances gave factor‐of‐two differences in chlorophyll concentrations compared to the use of a diel irradiance pattern with the same 24 h average value.

Portable chlorophyll meter (PCM-502) values are related to total chlorophyll concentration and photosynthetic capacity in papaya (Carica papaya L.)

This study was carried out to verify the practical use of the portable chlorophyll meter-PCM502 (PCM) in two papaya cultivars with contrasting green coloring of the leaf blade (‘Golden’: yellowish-green; ‘Solo’: dark green). The relationship was studied between the photosynthetic process and leaf nitrogen concentration, chlorophyll concentration and SPAD readings. The Portable Chlorophyll Meter (or SPAD meter) is a simple, portable, accurate, fast and inexpensive tool. Two Carica papaya L cultivars were grown in a greenhouse with 30 % interception in the photosynthetic active radiation (PAR). At 90 and 100 days after sowing (DAS), two groups of leaves from each cultivar were used for experiments. One group was considered as “young” leaves (3rd or 4th leaf from the apex) and one group as “mature” leaves (6th or 7th leaf from the apex). In these experimental conditions the following parameters were measured: net photosynthesis, Fv/Fm (potential maximal quantum yield of PSII), total chlorophyll concentration and leaf organic nitrogen. At SPAD values lower than 20 for ‘Golden” and 30 for ‘Solo’, the Fv/Fm ratios were correlated with the increase in the ratio as determined by the PCM. There were cultivar differences related to N allocation in the leaf. ‘Golden’ partitioned significantly less N to chlorophyll synthesis than ‘Solo’ at equivalent leaf N concentrations. This explains in large part the yellowish green leaf coloring of ‘Golden’ papaya. These cultivar differences in chlorophyll concentration were measurable with PCM technology. In contrast, at SPAD values <30 ‘Sunrise Solo’ had a greater rate of Fv/Fm decline than ‘Golden’ indicating that ‘Sunrise Solo’ was more sensitive to damage to PSII when N was limiting. At 90 and 100 days after planting, and with adequate water availability, PCM technology was able to evaluate the total chlorophyll molecules and maximum efficiency of PSII, meaning that the equipment can be used to diagnose physiological alterations related to N metabolism.

Physiological Response of Okra to Flea Beetle Herbivory as Measured by Leaf Loss, Chlorophyll Disruption, and Dry Matter Yield

Okra, Abelmoschus esculentus (L.) Moench, is attacked by the adult chrysomelid flea beetles, Podagrica spp. Information on physiological disruptions that occur due to flea beetle infestation affecting okra yield loss is incomplete. Screenhouse and field experiments were established to examine the effects of insect populations on leaf abscission, chlorophyll concentration, and biomass partitioning. Okra plants were grown in wire mesh screen cages and artificially infested with flea beetles, P. uniforma Jac., at population densities of 0, 5, 10, 20, 30, and 40 pairs per plant at 3 weeks after sowing (1 pair = 1 male and 1 female). In both experiments, okra plants had increased leaf abscission up to 100% at the 40-pair level in response to P. uniforma–induced injury. There were no significant differences in chlorophyll concentrations of plants at 0-, 5-, and 10-pair levels of infestation, suggesting the use of a compensatory mechanism by plants; at the 20-pair level a significant reduction occurred. Number of leaves per plant, shoots, roots, and dry fruit and total dry matter yield were reduced with infestation above the 20-pair level. More biomass was partitioned into roots at the 5- and 10-pair levels, but insect damage at populations beyond these levels completely suppressed the plant's ability to partition biomass. Dry fruit yields were reduced more than 50% when beetle populations increased beyond 20 pairs in both experiments. There was a correlation between insect density and number of leaves per plant and shoot, root, dry fruit, and total dry matter yield. The reduction in okra leaf production and chlorophyll content and increase in leaf abscission as a result of flea beetle infestation apparently resulted in a reduction in dry matter yield. The 20-pair level appeared to be the damage threshold of the insects. Physiological disruptions induced by the flea beetle at this level overcame the plants' ability to compensate for damage and caused significant reductions in leaf production, chlorophyll content, and dry matter yield and an increase in leaf abscission.

Detection of acid rain stress effect on plant using hyperspectral data in Three Gorges region, China

This paper aims to use hyperspectral data to detect the spectral change caused by acid stress to a native forest type in the Three Gorges region of China. For this purpose, a ground-based hyperspectral experiment was conducted at the Three Gorges region to detect acid deposition that caused Masson pine (Pinus massoniana) forest degradation. Continuum removal method was used to isolate wavebands more responsive to stress in wavelengths 450–750nm. The differences in chlorophyll concentrations and needle thickness caused by acidic stress are found to be explicable to the different spectral reflectance patterns in the visible and near-infrared wavelengths. Two new chlorotic indices were utilized to explain the stress-caused leaf chlorosis. The comparison of simulated vegetation indices and principal component analysis (PCA) results suggests that it would be possible to monitor acid rain stress effect on forest ecosystem from some wider spectral regions.

Carbon dioxide emission from olive oil pastes during the transformation process: technological spin offs

The emission of carbon dioxide (CO2) from olive paste during malaxation was investigated in a lab experiment using a hermetically sealed malaxation chamber. A rapid increase in the concentration of CO2 during malaxation was observed, with an average increase of 32 ml/(l min) for the initial 5 min. Then, the emission progressively decreased to a mean rate of 1.1 ml/(l min). This was probably the result of an initial acceleration in respiration followed by the gradual onset of fermentation processes as ambient oxygen was depleted. After malaxation, small amounts of cellular fermentation products (e.g. ethanol and lactic acid) were detected in the wastewater. In order to examine this phenomenon of the inhibition of oxidation due to evolved CO2, malaxation experiments were conducted in both a sealed and an open-air mixing apparatus. The differences in chlorophyll concentration of the resulting oils were then measured. Large amounts of chlorophyll, about twice as much, were found in the oil produced under sealed conditions. This increase in the concentration of chlorophyll resulted from the limited oxidation of the sample by atmospheric oxygen due to the protection of the evolved CO2.

Ecophysiological Differences Between Sterile and Fertile Fronds of the Subtropical Epiphytic Fern Pyrrosia lingua (Polypodiaceae) in Taiwan

Many ferns have specialized fronds that bear sporangia, whereas sterile fronds lack reproductive structures. Although a strong case can be made that the presence of the sporangia will affect the physiology of the frond, only one study could be located that investigated this phenomenon. Thus, ecophysiological (and some morphological) features of fertile fronds were compared with those of sterile fronds of the subtropical epiphytic fern Pyrrosia lingua in Taiwan. Fertile fronds were thicker than sterile fronds, a result of the presence of the large sori. Stomatal sizes and densities did not differ between the two types of fronds. The osmotic potential of liquid expressed from the fertile fronds was more negative than that of the liquid of sterile fronds, although this may be an artifact due to a matric effect of the released spores. No differences in chlorophyll concentrations (area basis only) and a/b ratios were found between sterile and fertile fronds. In situ rates of net CO2 exchange of the fertile fronds were substantially lower than those of the sterile fronds. Similar stomatal conductances and internal CO2 concentrations in the sterile fronds indicated that the efficiency of the photosynthetic apparatus was lower in fertile relative to sterile fronds. The results of this study indicate that the presence of sori on fronds of the epiphytic fern Pyrrosia lingua reduces the photosynthetic capacity of these fronds and, most likely, the productivity of plants harboring many fertile fronds.

Skin colour and pigment changes during ripening of ‘Hass’ avocado fruit

Skin of ‘Hass’ avocados (Persea americana Mill.) changes colour from green to purple/black as fruit ripen. This colour change is important as an indicator of ripeness for both industry and consumers. We sought to characterise pigment changes during ripening of ‘Hass’ avocados. Skin colour and changes in chlorophyll and anthocyanin concentrations in relation to fruit firmness at three ripening temperatures (15, 20 and 25 °C) were studied. As fruit ripened, skin colour changed from green, to purple, to black, which was observed as a decrease in L, chroma and hue. Total anthocyanins in skin tissue increased during ripening, but this increase was due almost entirely to a single anthocyanin; cyanidin 3-O-glucoside. Cyanidin 3-O-glucoside concentration increased after 3–6 days postharvest (depending on ripening temperature), and levels increased earlier, and were higher, with higher ripening temperature. Chlorophyll a and b levels decreased until 4–5 days after harvest, but did not change significantly thereafter. No significant differences in chlorophyll concentration were observed among the three ripening temperatures. Fruit harvested directly from the tree (unripe) with skin darkening showed similar pigments changes to that during ripening (reduced chlorophyll and increased cyanidin 3-O-glucoside). Colour change in ‘Hass’ avocados from green to purple, then black, results from an initial decrease in chlorophyll content, followed by an increase in the levels of the anthocyanin, cyanidin 3-O-glucoside.

Abundance and Sizes of Bay Scallops in Heterogeneous Habitats Along the Gulf Coast of Florida

Southern bay scallops (Argopecten irradians concentricus) form the basis of a recreational fishery along Florida's Gulf Coast. Recent declines in scallop abundances have led to significant harvest restrictions. As a way to gain insight into influences on scallop abundances and size, surveys of bay scallops and coastal habitats were conducted in two relatively undisturbed, shallow estuaries along the north-central Gulf Coast of Florida. Scallop abundances did not vary significantly between years or between locations kilometers apart. Shell heights did vary significantly between years at locations kilometers apart; however, these differences were not consistently related to differences in chlorophyll concentrations in the water column or distributions of benthic habitat classes. At the 100-m scale within locations, scallops were not proportionally distributed across the major habitat classes (i.e., Syringodium filiforme, Thalassia testudinum, mixed seagrass assemblage, other seagrasses, and areas of no/low seagrass cover). In general, proportionately more scallops were observed in association with S. filiforme, T. testudinum, and mixed seagrass habitats. Bay scallops collected from S. filiforme and areas of no/low grass cover were consistently 1-3 mm larger than those collected from T. testudinum and mixed seagrass assemblages. These results suggest the importance of S. filiforme and T. testudinum as habitats for bay scallops. The results also point to the need for further investigation into possible functional differences among seagrass species that may influence the ecology of bay scallops at a small spatial scale and the need for closer examination of scallop movement that may allow for active habitat selection. The work presented here, plus further efforts to elucidate the drivers of small-scale differences in scallop abundances and sizes, will benefit managers who seek to enhance scallop fisheries or protect and restore coastal habitats.

Surface chlorophyll in the Black Sea over 1978–1986 derived from satellite and in situ data

Absolute values of chlorophyll a concentration and its spatial and seasonal variations in the Black Sea were assessed by using satellite CZCS and in situ data. Since the satellite CZCS had operated for the 1978–1986 period, CZCS data was used for assessing the past state of the Black Sea just before the onset of drastic changes observed in late 1980s. The approach used for the calculation of the absolute values of chlorophyll a concentration from CZCS data was based on the direct comparison of in situ chlorophyll a data and those of CZCS and by applying the algorithm developed for the transformation of CZCS data into chlorophyll a values. CZCS Level 2 data related with pigment concentration having a spatial resolution of 1 km at nadir were used. The daily Level 3 files were derived by binning Level 2 values into 4-km grid cells and the monthly and seasonal Level 3 files were created by averaging the daily Level 3 files over the corresponding period. In situ chlorophyll a data were obtained by spectrophotometric and fluorometric methods in 15 scientific cruises over the 1978–1986 period. Total number of ship-measured data used for the comparison with those CZCS values was 590. Chlorophyll a concentration (Chl) was derived from CZCS values ( C) with regression equations Chl= kC; the coefficient of transformation k was calculated from six different data sets by taking into account distinctions between subregions and seasons. The reasons for difference in the k values have been analyzed. Statistical comparison of the chlorophyll a values measured in situ and those derived from CZCS data was based on log-transformed data and gave the following results: regression slope=0.842, regression intercept=−0.081, coefficient of determination ( R 2)=0.806, root–mean–square error=0.195. The mean monthly chlorophyll a distributions derived from CZCS data over 1978–1986 have been constructed and the mean seasonal chlorophyll a values in different regions have been calculated and analyzed. The significant difference in chlorophyll concentration between the western shelf regions and the open part of the Black Sea has been demonstrated, especially in warm season. At almost all seasons, the highest chlorophyll concentration is observed in the western interior shelf region which is under strong influence of Danube. The summer mean chlorophyll concentration in this region is ∼18 times higher than that in the open parts and about nine times higher than in the eastern shelf region. The greatest seasonal variations are observed in the open part of the Black Sea: chlorophyll concentration in cold season is four to six times higher than in summer and three to five times higher than in April and October. To the contrary, in the western interior shelf regions, the concentration is higher in May–October (about twice than that in November–March). Seasonal variations in the western outer shelf regions are smoothed out as compared with both the western interior shelf and the open regions.

High spectral resolution reflectance of douglas fir grown under different fertilization treatments: Experiment design and treatment effects

Douglas fir [ Pseudotsuga menziesii (Mirb.) Franco.] seedlings were grown with different fertilization treatments in an experiment designed to investigate the effects of foliar biochemistry on needle and canopy reflectance measurements. Potentially confounding effects of the covariance of canopy structure with foliar biochemical concentration were minimized by fertilizing after leaf expansion. Seedlings showed no significant differences in specific leaf area, % needle moisture, biomass, or LAI, but showed significantly different total nitrogen concentrations, and some differences in chlorophyll concentrations. Measurements were made of needle optical properties, and bidirectional reflectance was obtained of needles and of canopies. Canopy reflectance was acquired under sky illumination using two field spectroradiometers. Needle and canopy treatment differences were highly significant in the visible region. Some treatment differences were also found in broad-band regions in the infrared in the canopy reflectances. Narrow-band infrared differences were detected in needle first derivative spectra, and coincided with known protein absorption features. Needle and canopy bidirectional reflectances were similar, but narrow-band features found in the needle infrared spectra were not found in the canopy data. Two possibilities for the failure to detect these narrow features in the canopy data are a confounding effect from variability caused by illumination angle changes and/or the low signal-to-noise characteristics of the field spectroradiometer relative to the laboratory instrument. The suite of optical and structural measurements taken from the same set of trees should provide a useful data set for parameterizing canopy models aiming to predict high spectral resolution reflectance of canopies.

Quasistationary areas of chlorophyll concentration in the world ocean as observed satellite data

To estimate the seasonal progress of the production process over the planet and its long-standing trend it is important to measure not only the spatial distributions of pigment that represent the rates of photosynthesis but also their time variability. Anthropogenic impact on natural complexes can be efficiently estimated by satellite observations of phytopigment dynamics. This study presents CZCS satellite data processed to reveal spatial inhomogeneity in the seasonal course of chlorophyll concentration in the world ocean on a global scale. Areas with quasistationary and non-stationary seasonal changes in chlorophyll concentration are revealed for the 7.5 years period of CZCS operation. Areas in the world ocean with maximum absolute and relative differences in chlorophyll concentration during different seasons were found. Results are illustrated with a chart of areas in the Atlantic Ocean discerned by dynamic parameters.

Spectrometer for fast measurements of in vivo reflectance, absorptance, and fluorescence in the visible and near-infrared

A new type of VIRAF spectrometer (Visible Infrared Reflectance Absorptance Fluorescence), the VIRAF II, is presented. The VIRAF spectrometer has been developed and constructed for ground truthing of remote sensing of terrestrial vegetation and for other types of ecophysiological measurements. It is a multipurpose instrument with the capability to measure reflectance, absorptance, and fluorescence in the visible and near-infrared (400–910 nm). The position of the sample is unchanged throughout the measurements, which guarantees a good comparison between the different types of spectra. Since leaf samples can be left intact and attached to the plant, real in vivo measurements as well as long-term and repetitive studies using different additional techniques can be carried out. In contrast to conventional spectrometers, the sample is illuminated with strong white (or blue) light and only a narrow angle of the reflected, transmitted, or emitted light is detected. This mimics the outdoor situation in remote sensing. Furthermore, the strong light maintains the physiological activity of the leaf sample. The new VIRAF II described here has a diode array detector and a shutter which enables to measure within 20 ms. This opens the possibility for studies of kinetic changes in the range of seconds or minutes. Results are presented from a comparison of light green leaves of an Aurea mutant and dark green leaves of a wildtype tobacco plant ( Nicotiana tabacum L.). The data are interpreted in terms of difference in chlorophyll concentration, leaf tissue structure, epidermis structure, and photosynthetic activity. Slight differences between the 20-ms reflectance spectra of a dark-adapted leaf taken directly after onset of illumination and after 60 s or 180 s of continuous illumination (decrease between 650 nm and 800 nm and increase between 400 nm and 600 nm) may be attributed to changes of the chlorophyll fluorescence and to chloroplast movements, respectively, reflecting physiological activity of the sample.