Total Pigment Content Research Articles

The extraction of pigments from fresh Laminaria japonica

The pigments in Laminaria japonica was extracted with six organic solvents and analyzed in spectroscopy analysis. The extractions conditions were screened by an orthogonal test and the quantity of extracted pigments was determined spectroscopically. The results show that: (1) among the six organic solvents, acetone was the most effective one for the extraction; (2) the optimum extraction conditions were as follows: the ratio of S/M (solvent volume/ material weight) was 30 ml/g; fresh seaweed was extracted 2 times in 2 h; (3) the average total content of pigments was 1.85 mg/g (calculated with dry L. japonica).

Chemical properties of cow and beef muscles: Benchmarking the differences and similarities1,2

The objective of this study was to identify muscles from cow populations that are equivalent or may possibly be made equivalent to muscles from A-maturity, Select-grade cattle in terms of chemical, compositional, and color characteristics. Objective color, expressible moisture, proximate composition, pH, heme iron concentration, and total collagen content were determined for 9 muscles (M. gluteus medius, M. infraspinatus, M. longissimus dorsi, M. psoas major, M. rectus femoris, M. tensor fascia latae, M. teres major, M. triceps brachii lateral-head, and M. triceps brachii long-head) from 15 cattle from each of 5 commercially identified populations [fed beef cows (B-F), non-fed beef cows (B-NF), fed dairy cows (D-F), non-fed dairy cows (D-NF), and A-maturity, Select-grade cattle (SEL)]. Muscles from B-F and B-NF populations were more similar to the SEL than were the D-F and D-NF. There were 2 muscles, the M. infraspinatus and M. teres major, from the population of B-F that were similar, physically and chemically, to SEL in most traits. The majority of the 9 muscles from the cows did not differ (P < 0.05) from SEL for percentage expressible moisture, proximate composition, and total collagen content. However, notable differences in pH, objective color L*, total pigment content, and heme iron content existed between cow populations and SEL. The muscles from SEL had significantly (P < 0.05) lower total pigment and heme iron concentrations. These differences likely relate to the visual appearance of muscles from the different populations of cattle. Two of the 9 muscles studied were similar among cow populations and A-maturity, Select-grade beef.

Estimating chlorophyll concentration in conifer needles with hyperspectral data: An assessment at the needle and canopy level

This investigation quantitatively links chlorophyll a + b (chl a + b ) concentration, a physiological marker of forest health condition, to hyperspectral observations of Jack Pine ( Pinus banksiana), a dominant Boreal forest species. Compact Airborne Spectrographic Imager (CASI) observations, in the visible-near infrared domain, were acquired over eight selected Jack Pine sites, near Sudbury, Ontario, between June and September of 2001. Supplementing the airborne campaigns was concurrent on-site collection of foliage samples for laboratory spectral and chemical measurements. The study first connected needle-level optical properties with pigment concentration through the inversion of radiative transfer models, LIBERTY and PROSPECT. Next, a chlorophyll sensitive optical index (R750/R710), was “scaled-up” using SAILH, a turbid medium canopy model, to estimate total pigment content at the canopy-level. Due to the potential confounding effects of open canopy structure and foliage clumping, the analysis accordingly focused on high spatial resolution CASI imagery (1 m) to visually target tree crowns, while accounting for shadowed areas. Chl a + b concentration estimation from airborne spectral data using coupled leaf and canopy models was shown to be feasible with a root mean square error of 5.3 μg/cm 2, for a pigment range of 25.7 to 45.9 μg/cm 2. Such predictive algorithms using airborne-level data provide the methodology to be potentially scaled-up to satellite-level hyperspectral platforms for large scale monitoring of vegetation productivity and forest stand condition.

Photoinhibition and photosynthetic pigment reorganisation dynamics in light/darkness cycles as photoprotective mechanisms of &lt;em&gt;Porphyra umbilicalis&lt;/em&gt; against damaging effects of UV radiation

Porphyra umbilicalis L. Kutzing collected from the upper intertidal zone at Helgoland, North Sea, was exposed to different spectral ranges of UV radiation under both 12/12 h light/dark cycles and continuous irradiation. In light/dark cycles, oscillations of the optimal quantum yield (Fv /Fm) were observed during the experiments, reaching maximal values at the end of the light phase followed by lower values during the dark phase. Decreased Fv /Fm was observed in thalli illuminated with photosynthetic active radiation (PAR) plus UV-A and PAR+UV-A+UV-B, compared with the PAR control, indicating a certain degree of UV-induced photoinhibition. In addition, a decrease in the percentage of change of the linear initial slope and maximum electron transport rate (ETR) estimated from ETR vs. irradiance curves was induced by UV radiation during the light phase. Recovery during the 12 h dark phase was almost completed in UV-A treated plants. PAR+UV-A seemed not to affect the photosynthesis, measured as O2 production. However, a decrease in O2 production was observed in the PAR+UV-A+UV-B treatment, but it recovered to initial values after 48 h of culture. No changes in total content of photosynthetic pigments were observed. However, thallus absorptance and the in vivo absorption cross-section in the PAR range (400-700 nm) normalised to Chl a (a* parameter) fluctuated during light/dark cycles and were positively correlated with changes in the optimum quantum yield, thus indicating that daily pigment reorganisation in the light-harvesting complex may play a key role in the photosynthetic performance of the algae. Both UV-A and UV-B treatments under continuous irradiation induced a significant reduction in the optimal quantum yield, ETR efficiency and photosynthetic oxygen production during the first 36 h to values around 30% of the initial ones. Thus, different protective mechanisms against UV stress can be observed in P. umbilicalis: dynamic photoinhibition when UVA is combined with PAR, followed by full recovery of photosynthesis during the dark phase, and a more pronounced photoinhibition under UV-B, with only partial recovery after longer time periods, in which photosynthetic pigment reorganisation plays an important role.

Photosynthesis and photoinhibition of two green macroalgae with contrasting habitats

We evaluated light-related traits ofUlva pertusa Kjellman from the intertidal and upper subtidal zones, and ofUmbraulva japonica (Holmes) Bae & Lee (formerlyUlva japonica) within its upper growth limit of 10 m, in Korean coastal regions.U. pertusa showed significantly higher maximum photosynthetic rates, photosynthetic efficiency, saturating irradiances, and total pigment contents. However, green light-use efficiency at limiting irradiances was notably higher inU. japonica, possibly due to the presence of green light absorbing pigments like siphonaxanthin and siphonein. Non-enzymatic antioxidation capacity as determined by DPPH (α,α-diphenyl-β-picrylhydrazyl) radical scavenging rate was markedly higher inU. pertusa (50.49%) than inU. japonica (8.85%). Both species showed a substantial decrease in optimal photosystem (PS) II efficiency (Fv/ Fm) with increasing PAR doses despite the degree of photoinhibition being more marked inU. japonica. After 24 h in dim light,U. pertusa rapidly and almost fully recovered Fv/ Fm within an hour whileU. japonica exhibited slow and incomplete PSII recovery over the full recovery period. A significant depression in photosynthetic activity with monochromatic UV-B radiation was observed inU. japonica only, followed by slight recovery in dim light. Light use efficiency and high irradiance tolerance may be important ecological axes along which the niche separation of green foliose algae occurs in Korean coastal waters.

A new pigment for smart anticorrosive coatings

The purpose of this paper was to evaluate the performance of a modified zeolite as an anticorrosive pigment for paints. A procedure to prepare the pigment was outlined and its anticorrosive properties assessed following the electrochemical behavior of a steel electrode in pigment suspension. In a second stage, alkyd paints were formulated employing different anticorrosive pigments: (1) 30% by volume (v/v) of the modified zeolitic rock, (2) 10% (v/v) of zinc phosphate, and (3) a mixture of 10% (v/v) zinc phosphate plus 20% (v/v) of the modified zeolitic rock. In every case, percentages were referred to the total pigment content. Titanium dioxide, zinc oxide, and barium sulfate were incorporated to complete the pigment formula. The pigment volume concentration/critical pigment volume concentration (PVC/CPVC) ratio was 0.8. The performance of the resulting anticorrosive paints was assessed by accelerated (salt spray and humidity chambers) tests and electrochemical (corrosion potential, ionic resistance, and polarization resistance) essays. It was demonstrated that the modified zeolite is effective in protecting steel from corrosion when it is used in combination with zinc phosphate. There exists a synergism between the modified zeolite and zinc phosphate that allows the zinc phosphate content in anticorrosive paints to be reduced.

Pigment Profiles in Monovarietal Wines Produced in Uruguay

The aim of this study was to determine by HPLC-DAD-MS the pigment profiles and the different anthocyanin-derived pigment formation in four monovarietal young red wines produced in Uruguay from different grape varieties (Caladoc, Marselan, Marzemino, and Cheveñasco) and compare them to that of a young <i>Vitis vinifera</i> cv. Tannat wine produced in the same vintage. In quantitative terms, Tannat wine had the highest total pigment content whereas Cheveñasco had the lowest. Results showed differences not only in anthocyanin composition but also in the chemical nature of the major anthocyanin-derived pigments present in each wine. Tannat had the lowest content in derived pigments, vitisin A being the most representative. Caladoc and Marselan were characterized by the highest percentages of malvidin-3-glucoside and its acyl derivatives. The 4-vinylphenol derivative of malvidin-3-glucoside was the major pyranoanthocyanin in both wines, along with vitisin A in Caladoc and vitisin B in Marselan. The major anthocyanin-derived pigments of Marzemino were B-type vitisins. Marzemino also contained anthocyanin-flavanol acetaldehyde-mediated condensation products, which might indicate higher levels of acetaldehyde in this wine than in the others. Cheveñasco had the highest percentage of derived pigments, with the 4-vinylphenol derivative of malvidin-3-glucoside the most representative and the second most abundant compound after malvidin-3-glucoside.

Chlorophyll and Carotenoid Profile and Enzymatic Activities (Chlorophyllase and Lipoxygenase) in Olive Drupes from the Fruit-setting Period to Harvest Time

The aim of this study was to monitor the pigment profile and chlorophyllase (Chlase) and lipoxygenase (Lox) activities of olive (Olea europaea L.) drupes during the development of the fruit from `Arbequina' and `Farga' in order to find better ways to characterize cultivars such as `Arbequina' that produce virgin olive oils that are highly appreciated in international markets. `Farga' was included as a comparative reference. The total pigment content in olive drupes from the two cultivars studied suffered a decrease when the maturation process began, the rate of chlorophyll degradation being more marked than that of the carotenoid pigment. Chlorophyllides a and b, cis-α-carotene, β-cryptoxanthin, and esterified xanthophylls were detected only in `Arbequina' fruit. The behavior of the Chlase and Lox activities in both cultivars was different. Chlase activity in olives from `Farga' was detected only at the end of the pit hardening period, but in the case of `Arbequina' the presence of dephytilated chlorophyllic derivatives is directly related to a higher Chlase enzymatic activity than that of `Farga' fruit. Although the level of these enzymatic activities decreased when ripening advanced in both cultivars, in `Arbequina' both enzymes showed a slight increase of activity at the latest stages of ripening.

Effect of dietary fatty acids on the oxidative stability and the colour of broiler meat

The aim of our investigation was to determine the effects of increased PUFA (polyunsaturated fatty acids) content on the colour, total pigment content, organoleptic characteristics and oxidative stability of poultry meat. The experiment was carried out with 1200 Ross-308 cock chicklings. Animals were fed with a 3 phase diet, and in each phase, additional fat was added to the feed. The isocaloric and isonitrogenic feed was produced as the breeder organization suggested; only the fat content differed (4 treatments: pig fat (lard), sunflower oil, soy oil, flax-seed oil).The different fat complements did not influence broiler production. However, the fatty acid composition of meat was similar to the fatty acid composition of feed (additional fats). The analyses of meat samples, after a storage period, did not significantly prove the possible negative effects of higher PUFA content.

BIOLOGICALLY ACTIVE SUBSTANCES OF THE HERB OF URTICA DIOICA

We have established the qualitative composition and the quantitative content of biologically active substances of the herb of Urtica dioica. Aminoacid composition, monosaccharide set of PSK and PV, the presence of 4 macro- and 18 microelements and their quantitative content have been studied for the first time. Investigating the phenol composition of the herb of Urtica dioica by HPLC has revealed in the raw material alongside with the previously described gallic, coffeic acids, rutine and quercetine the presence of hyperoside, luteolin-7-glycoside, 3,4-isoramnetin diglycoside, chlorogenic acid, aesculetin. We were the first to determine the total content of water-soluble polysaccharides, pectin substances, astringent substances, pigments (carotenoids and chlorophylls),vitamin K1, triterpene compounds and saponins of the triterpene type.

Growth of etiolated barley plants in weak static and 50 Hz electromagnetic fields tuned to calcium ion cyclotron resonance.

BackgroundThe effects of weak magnetic and electromagnetic fields in biology have been intensively studied on animals, microorganisms and humans, but comparably less on plants. Perception mechanisms were attributed originally to ferrimagnetism, but later discoveries required additional explanations like the "radical pair mechanism" and the "Ion cyclotron resonance" (ICR), primarily considered by Liboff. The latter predicts effects by small ions involved in biological processes, that occur in definite frequency- and intensity ranges ("windows") of simultaneously impacting magnetic and electromagnetic fields related by a linear equation, which meanwhile is proven by a number of in vivo and in vitro experiments.MethodsBarley seedlings (Hordeum vulgare, L. var. Steffi) were grown in the dark for 5 and 6 days under static magnetic and 50 Hz electromagnetic fields matching the ICR conditions of Ca2+. Control cultures were grown under normal geomagnetic conditions, not matching this ICR. Morphology, pigmentation and long-term development of the adult plants were subsequently investigated.ResultsThe shoots of plants exposed to Ca2+-ICR exposed grew 15–20% shorter compared to the controls, the plant weight was 10–12% lower, and they had longer coleoptiles that were adhering stronger to the primary leaf tissue. The total pigment contents of protochlorophyllide (PChlide) and carotenoids were significantly decreased. The rate of PChlide regeneration after light irradiation was reduced for the Ca2+-ICR exposed plants, also the Shibata shift was slightly delayed. Even a longer subsequent natural growing phase without any additional fields could only partially eliminate these effects: the plants initially exposed to Ca2+-ICR were still significantly shorter and had a lower chlorophyll (a+b) content compared to the controls. A continued cultivation and observation of the adult plants under natural conditions without any artificial electromagnetic fields showed a retardation of the originally Ca2+-ICR exposed plants compared to control cultures lasting several weeks, with an increased tendency for dehydration.ConclusionA direct influence of the applied MF and EMF is discussed affecting Ca2+ levels via the ICR mechanism. It influences the available Ca2+ and thereby regulatory processes. Theoretical considerations on molecular level focus on ionic interactions with water related to models using quantum electrodynamics.

Zeolitic rock as a new pigment for ceiling paints.: Influence of the pigment volume concentration

The performance of a zeolitic rock, mainly clinoptilolitic (heated at 350 °C) is studied as humidity and ammonia adsorber in ceiling paints. The paints were formulated with 39% and 75% of zeolitic rock by volume of the total pigment content and 75% and 85% pigment volume concentration (PVC). A blank, without zeolitic rock, was also formulated. The performance of the paints were assessed by gas (water and ammonia) adsorption and adsorption–desorption cycled tests. The results show that the paints containing zeolitic rock have better performance than the blank. Moreover, paints with 75% PVC behaved better than paints with PVC 85%. This behaviour may be due to the higher pigment content because the paints with PVC 85% retain more water during the curing period diminishing their adsorption capacity.

Remote sensing algorithms for monitoring eutrophication in Ishizuchi storm water reservoir in Kochi Prefecture, Japan / Algorithmes de télédétection pour la surveillance de l'eutrophisation du réservoir d'orage d'Ishizuchi dans la Préfecture de Kochi, Japon

Remote sensing technology is being conceived as a cost-effective tool to monitor the eutrophication problem in shallow inland lakes and reservoirs. The objective of this study is to develop hyperspectral remote sensing algorithms for chlorophyll and accessory pigments retrieval in the Ishizuchi Reservoir in Japan. The laboratory reflectance data of 207 field samples with manipulated pigment and suspended sediment concentrations were measured between 400 and 700 nm with a hyperspectral spectroradiometer, and integrated into 60 contiguous narrow bands. Band ratio and spectral absorption algorithms were developed by regression analysis with the observed chlorophyll measurements, and their estimation accuracies were evaluated using the RMSE of the estimates. Algorithms developed from spectral absorption ratios a(675 nm)/a*(675 nm) for five different classes of total pigment concentrations were more accurate than the algorithms based on band ratios Rrs (538 nm)/Rrs (488 nm), Rrs (581 nm)/Rrs (463 nm) and Rrs (674 nm)/Rrs (622 nm) as a result of removing the influence of overlapping absorption and scattering by water molecules and suspended solids from total absorption spectra.

Pigment Distribution and Total Dissolved Solids of Selected Cycles of Table Beet from a Recurrent Selection Program for Increased Pigment

Half-sib recurrent selection programs were initiated at the University of Wisconsin-Madison in 1978 and 1995 to increase betalain (betacyanin and betaxanthin) concentration in red and yellow table beets (Beta vulgaris L. ssp. vulgaris), respectively. Cycles of selection from both the red and yellow table beet breeding programs were evaluated for pigment and total dissolved solids (TDS) distribution in five tissue sections (outer, middle and center zones of the root; leaf and petiole) in two environments (early and late planting) during 2002. Betaxanthin concentration increased with the later planting date in the majority of the tissue zones in the yellow and red table beet populations. Absolute pigment concentration of the outer root zone increased the most over cycles of selection: 46.6 mg/100 g fresh weight (FW) betaxanthin and 201 mg/100 g FW betacyanin for yellow and red populations, respectively. However, the greatest rate of gain was in the center and middle tissue zones. Selection based on the outer 2 cm of root tissue has effectively increased pigmentation of the entire beet plant. A correlated response to selection in leaf and petiole tissue was measured for pigment concentration in both populations. The contribution of each tissue zone to total pigment concentration of the beet plant remained constant throughout cycles of selection averaging 39%, 25%, 25%, 6%, and 5% for outer, middle, center, petiole and leaf tissue zones, respectively. Across all table beet populations, pigment concentration of the outer root zone was 55% and 62% higher than middle and center zones, respectively. TDS of the outer root zone was 10% and 12% higher than middle and center zones, respectively.

Rheological characterization of coloured oil-in-water food emulsions with lutein and phycocyanin added to the oil and aqueous phases

The use of natural colourings in food products presents nutritional advantages, and certain pigments are associated with functional properties, e.g. antioxidant effects. This can be very advantageous in food products with high fat contents like mayonnaises. The aim of this work was to study the effect of adding natural pigments, lutein and phycocyanin, to the water and oil phases, respectively, of oil-in-water pea protein-stabilized emulsions, beyond the desirable and expected development of a green colour. The emulsions were prepared with 3% (w/w) pea protein, 65% (w/w) vegetable oil, and varying concentrations of lutein and phycocyanin (0.25–1.25% w/w). Emulsions containing both pigments, in different proportions (total pigment concentration of 0.5%, w/w) were also prepared. Oscillatory and steady-state measurements, as well as droplet size distribution and textural profile tests, were performed. The addition of lutein to the disperse oil phase promoted a decrease of the emulsions' rheological and textural parameters, while the addition of phycocyanin to the water (continuous) phase resulted in an increase of these properties. When using combinations of both pigments, an increase of the rheological and textural parameters with phycocyanin proportion was apparent, and a synergetic effect due to the presence of both pigments was found.

Effect of storage on the original pigment profile of spanish virgin olive oil

AbstractThe present study was carried out on 12 virgin olive oils to determine whether one year's storage under mild conditions of 15°C and darkness affected the initial pigment composition of recently extracted virgin olive oil. Although the total pigment content remained constant, the individual contribution of each pigment changed. The acid compounds liberated from the fruits during the oil extraction process promote the beginning of chlorophyll pheophytinization and the isomerization of the 5,6‐epoxide groups of the minor xanthophylls. During the first 3 mon of storage, there was a generalized increase in pheophytinization that was different for each oil (P&lt;0.01, Duncan test) but was not correlated with the free acidity measured in them. At the same time, isomerized xanthophylls and allomerized pheophytins increased slightly. Following this stage, pyropheophytin a (a pigment not present in the initial oils), was detected; its concentration increased during storage. There were no significant differences in the final percentages of pyropheophytin a among the 12 oils, and the concentration of this new compound represented around 3% of the chlorophyll fraction. The pheophytin a/pyropheophytin a ratio always exceeded 20. All these small pigment transformations were signs that the oil had been stored. The content and class of pigments present in virgin olive oil are authentic indicators of its history prior to marketing.

Protozooplankton community structure and grazing impact in the eastern Atlantic sector of the Southern Ocean in austral summer 1998

Abstract The protozooplankton community structure and grazing impact within the winter ice-edge zone (WIE), spring ice-edge zone (SIE) and in the vicinity of the Antarctic Polar Front (APF) in the eastern Atlantic sector of the Southern Ocean was investigated in austral summer (December 97—January 98). Total chlorophyll-a (Chl-a) concentrations in the vicinity of the SIZ and APF were always >0.5 μg l while at stations within the SIE total pigment concentrations were always 20 μm fraction was always dominated by ciliates comprising aloricates and tintinnids and dinoflagellates. The contribution of the larger components to the total was, however, always 60% of total pigment. These results suggest that the grazing impact of the protozooplankton was largely mediated by the contribution of the small phytoplankton cells to total pigment.

Meat quality of entire and castrated male Boer goats raised under Australian conditions and slaughtered at different weights: physical characteristics, shear force values and eating quality profiles

AbstractCastrated and entire Boer bucks (no. = 60) in groups of between three and five animals were slaughtered at 5,15, 30, 45, 60, 75, 90 and 105 kg live weight (5- and 15-kg animals were not castrated). Ultimate pH, muscle colour (subjective and objective measurement), subcutaneous fat colour, total pigment concentration, shear force values and eating quality were investigated. The ultimate pH o/longissimus muscle increased from 5-7 to 6-2 (P &lt; 0-05) as animals were slaughtered at heavier weights. Slaughter weight had an influence on chromameter muscle colour (L*, a*, b* values) and subjective muscle colour scores recorded using a nine-point colour scale (P &lt; 0-05) for both entire and castrated bucks. Muscle redness (a* values) and subjective muscle colour scores increased gradually in older animals while muscle lightness and yellowness (L* and b* values) decreased. Subcutaneous fat colour became more yellow at heavier slaughter weights (P &lt; 0-05). Shear force values were affected (P &lt; 0-05) by slaughter weight but not by castration of bucks. All eating quality scores were influenced by slaughter weight but not by castration, and flavour, as predicted by eating quality scores, was the most important attribute that contributed to overall acceptability of the goat meat.

Phenolic compounds in acerola fruit (Malpighia punicifolia, L.)

Anthocyanin aglycons and other phenolic compounds were identified in acerola (Malpighia punicifolia, L.). Anthocyanins, flavonoids and phenolic acids were fractionated and characterized by means of chromatographic and spectral data. The total content of anthocyanin pigments was 37.5 mg per 100 g of ripe acerola skin. The phenolic pigments identified were pelargonidin, malvidin 3,5-diglycoside and cyanidin 3-glycoside. Quercetin, kaempferol and the phenolic acids p-coumaric acid, ferulic, caffeic and chlorogenic were also identified.

The annual cycle of phytoplankton photosynthetic quantum efficiency, pigment composition and optical properties in the western English Channel

Phytoplankton photosynthetic quantum efficiency (PQE), pigments, absorption characteristics, species composition (converted to phytoplankton carbon, Cph) and other variables were measured at an offshore site in the western English Channel throughout 2001, using an opportunistic weekly sampling schedule. The variation of chlorophyll-a (Chla) and other phytoplankton pigments followed the classical seasonal cycle, driven by incident light, patterns of stratification and nutrient availability. Phytoplankton and pigment concentrations were low in the winter, rising to a peak in the spring ‘bloom’, with episodic blooms throughout the summer, an autumn bloom and a decline to the winter minimum. Surface layer Chla and total pigment (Tpig) concentrations were highly correlated for the whole year, yet it was observed that the fraction of Chla in Tpig (Chla/Tpig) was not constant and had a distinct seasonal pattern, low in winter and higher in spring, summer and autumn blooms. Chlorophyll-a/Tpig was linearly correlated with recent ambient light fluxes and maximum PQE (PQEm) throughout most of the year, though more significantly within seasonal periods. Chlorophyll-a and Tpig were both linearly correlated to Cph and the Chla/Cph ratio was significantly correlated with both Chla/Tpig and PQEm. Also the optical absorption ratios, a674/a443 and a674/a490 were significantly correlated with PQE and Chla/Tpig, indicating probable optical signatures for these two parameters. The seasonal cycle of measurements of photosynthetic quantum efficiency provided a bench-mark against which all the photosynthetically-driven seasonal changes of biological properties can be understood, in terms of incident solar radiation and nutrient availability. We conclude that phytoplankton synthesize Chla preferentially to other pigments or carbon compounds in conditions beneficial to growth. The PQEm, the ratios of Chla/Tpig, Chla/Cph and a674/a443 are greater when plants are growing actively. In periods of nutrient sufficiency, PQEm, Chla/Tpig and a674/a443 are all linear functions of the mean total photon flux for the recent few days. Photosynthetically driven changes in Chla synthesis, cause observed changes of Chla/Tpig and Chla/Cph ratios.