The carbon and chlorophyll content of phytoplankton from various nutrient regimes

We have measured the relationship between chlorophyll and carbonin phytoplankton cultures and natural populations of phytoplanktonusing simple standard extraction procedures without correctionfor degradation products. During exponential growth of fourcultures of unicellular and colonial green algae and one diatom,chlorophyll varied from 1.22 to 6.08% of the phytoplankton carboncontent (=3.03%). The chlorophyll content of the cultures was lower during nitrogen and phosphorus deficiency.Results from natural populations of phytoplankton from eutrophiclakes and from a coastal marine station gave values mostly rangingfrom 1.5 to 3.7% chlorophyll, corresponding to carbon/chlorophyllratios of 27–67. If only a rough estimate of the phytoplanktoncarbon biomass is required, a simple, efficient extraction procedurecan be used without any corrections for degradation products.     

Water-mass influences on summer Antarctic phytoplankton biomass and community structure

The association between the variability of phytoplankton biomass and community structure and the distribution of water masses around the Antarctic Peninsula were examined during austral summer 1993. Phytoplankton biomass showed high variability, and was dominated by an autotrophic flagellate (Cryptomonas sp.) that represented, on average, 91% of total phytoplankton biomass. The lowest phytoplankton biomasses were associated with the strongly mixed, saline, cold waters characteristic of the Weddell Sea water mass, and with the waters influenced by ice melt from the Bellingshausen Sea. The highest biomasses were found in the confluence of these water masses, where a front develops. Community composition also differed among water masses, with eukariotic picoplankton and diatoms having their highest relative contribution to community biomass in stations with Bellingshausen Sea and Weddell Sea water masses, whereas the abundance of Cryptomonas sp. was highest at the confluence of these waters. These results indicate that mesoscale processes, that determine water mass distribution, are of paramount importance in controlling the time and space variability of Antarctic phytoplankton.     

Impact of nutrients on photoacclimation of phytoplankton in an oligotrophic lake measured with long-term and high-frequency data: implications for chlorophyll as an estimate of phytoplankton biomass

Hydrobiologia - Chlorophyll measurements are commonly used to estimate phytoplankton biomass. However, phytoplankton readily acclimate to variations in light through a range of phenotypic...     

Plastid structure and chlorophyll content in leaf primordia of onion bulbs

Angiosperms do not synthesize chlorophyll in the dark. Here we show that leaf primordia in onion bulbs are green, though they developing in dark conditions. We present results that show plastids in green primordia are chloroplasts, and that they contain chlorophyll as well as embryos in seeds of certain angiosperms.     

The structure of the phytoplankton community in the subsurface chlorophyll maxima in the western North Pacific Ocean

The phytoplankton taxonomic composition of the subsurface chlorophyllmaximum layer (SCM) was compared with that of the surface layerin July, September and November 1979 in the western North PacificOcean. Besides the use of chemical fixatives for preservablephytoplankton, serial dilution culture method was employed fornon-preservable flagellates and monads, i.e., fragile forms.The SCM was characterized by a high species diversity of preservablephytoplankton and by the numerical dominance of fragile forms.Among the fragile forms, Micromonas and Ochromonas were dominant.This dominance is consistent with their viability at low lightintensity. Cluster analysis revealed that, for blue-green algae,coccolithophorids, silicoflagellates and diatoms, a marked differenceexisted in species assemblages between the SCM and the surfacebut there was no distinct difference in dinoflagellate assemblages.The difference between both layers is discussed, as relatedto the mechanisms of formation of the SCM. ¹Present address: Nodai Research Institute, Tokyo Universityof Agriculture, 1-1-1, Sakuragaoka, Setagaya-ku, Tokyo 156,Japan.     

The annual cycles of phytoplankton biomass

Terrestrial plants are powerful climate sentinels because their annual cycles of growth, reproduction and senescence are finely tuned to the annual climate cycle having a period of one year. Consistency in the seasonal phasing of terrestrial plant activity provides a relatively low-noise background from which phenological shifts can be detected and attributed to climate change. Here, we ask whether phytoplankton biomass also fluctuates over a consistent annual cycle in lake, estuarine–coastal and ocean ecosystems and whether there is a characteristic phenology of phytoplankton as a consistent phase and amplitude of variability. We compiled 125 time series of phytoplankton biomass (chlorophyll a concentration) from temperate and subtropical zones and used wavelet analysis to extract their dominant periods of variability and the recurrence strength at those periods. Fewer than half (48%) of the series had a dominant 12-month period of variability, commonly expressed as the canonical spring-bloom pattern. About 20 per cent had a dominant six-month period of variability, commonly expressed as the spring and autumn or winter and summer blooms of temperate lakes and oceans. These annual patterns varied in recurrence strength across sites, and did not persist over the full series duration at some sites. About a third of the series had no component of variability at either the six- or 12-month period, reflecting a series of irregular pulses of biomass. These findings show that there is high variability of annual phytoplankton cycles across ecosystems, and that climate-driven annual cycles can be obscured by other drivers of population variability, including human disturbance, aperiodic weather events and strong trophic coupling between phytoplankton and their consumers. Regulation of phytoplankton biomass by multiple processes operating at multiple time scales adds complexity to the challenge of detecting climate-driven trends in aquatic ecosystems where the noise to signal ratio is high.     

Seasonal pattern of photosynthetic rate and its relationship with chlorophyll content,ribulose-1,5-bisphosphate carboxylase activity and biomass production

Net photosynthetic rate (P_N), ribulose-1,5-bisphosphate carboxylase (RuBPC) activity, chlorophyll (Chl) content and biomass production were estimated at monthly intervals inChukrasia tabularis, Dolichandrone atrovirens, Eugenia jambolana, Gmelina arborea, Lannea coromandelica, Terminalia arjuna andTerminalia bellerica from September 1990 to August 1991. The leaves of all the seven tree species showed significantly higher P_N during summer than in winter and these rates differed from one species to the other. A positive correlation was found between P_N of different tree species and their Chl content or biomass production. There was no significant correlation between ribulose-1,5-bisphosphate carboxylase activity and P_N when these were expressed on leaf area basis.     

Seasonal pattern of photosynthetic rate and its relationship with chlorophyll content,ribulose-1,5-bisphosphate carboxylase activity and biomass production

Net photosynthetic rate (P_N), ribulose-1,5-bisphosphate carboxylase (RuBPC) activity, chlorophyll (Chl) content and biomass production were estimated at monthly intervals inChukrasia tabularis, Dolichandrone atrovirens, Eugenia jambolana, Gmelina arborea, Lannea coromandelica, Terminalia arjuna andTerminalia bellerica from September 1990 to August 1991. The leaves of all the seven tree species showed significantly higher P_N during summer than in winter and these rates differed from one species to the other. A positive correlation was found between P_N of different tree species and their Chl content or biomass production. There was no significant correlation between ribulose-1,5-bisphosphate carboxylase activity and P_N when these were expressed on leaf area basis.     

Deep chlorophyll maxima and UVR acclimation by epilimnetic phytoplankton

1. It is well established that ultraviolet radiation (UVR) has many harmful effects on phytoplankton, but the factors controlling algal sensitivity to UVR are not fully understood. 2. We exposed phytoplankton communities from the epilimnia and deep chlorophyll maxima (DCM) of 2 Canadian lakes to 14 irradiance treatments of various spectral quality and monitored changes in the maximum quantum efficiency of Photosystem II photochemistry (F_v/F_m) using a pulse amplitude modulation fluorometer. 3. Phytoplankton from DCM did not show marked differences from epilimnetic communities in taxonomy or nutrient status, but exhibited substantially higher photosynthetic impairment under UVR exposure. 4. Our results suggest that epilimnetic phytoplankton acclimate to in situ light conditions in a spectrally‐specific manner, and that ultraviolet‐A radiation is a stronger stressor than ultraviolet‐B or photosynthetically active radiation in the mixed layers of our study lakes. Model estimates of damage and recovery rate constants revealed that the phytoplankton of the two lakes relied upon different strategies of UVR‐acclimation, in one lake minimising susceptibility to photodamage and in the other maximising recovery efficiency.     

Relations between production and biomass of phytoplankton in four Swedish lakes of different trophic status and humic content

Production and biomass values from phytoplankton populations in four different Swedish lakes were analysed. The production in all lakes was directly proportional to biomass during homothermal periods. When the lakes were stratified there was a strong negative relation between specific growth rate and biomass. The data fitted to a logistic density dependent growth equation of the form: dB/ dt = µ_mB(1-B · K^–1) where B is the biomass, µ_m the maximum specific growth rate and K the carrying capacity. The equation was used to derive the parameters µ · µ_m ^–1 and carrying capacity (the maximum possible biomass). These parameters were then discussed in relation to light climate, phosphorus concentration and humic content.     

The effect of kinetin and auxin on the chloroplast structure and chlorophyll content in wheat coleoptiles

Kinetin and auxin when applied to excised segments of wheat coleoptiles bring about changes in chloroplast structure and chlorophyll content of parenchymatous cells. Auxin (IAA) alone at a concentration of 10^-5M stimulated the elongation (growth), but the chloroplast membrane system was less developed and the chlorophyll content was lowest in comparison with control and other variants. Kinetin (KIN) exhibited various effects depending on the concentration used. 10^-6M KIN somehow stimulated the elongation and enhanced the amount of grana coming to one chloroplast section, but the individual grana were relatively small and the chlorophyll content a little higher than in the control. On the other hand 10^-5M KIN which did not promote the elongation of wheat coleoptiles, had the maximum stimulatory effect on the chloroplast membrane system, especially on the occurrence of large grana, and the chlorophyll content was highest in comparison with the other variants. The occurrence of starch grains in chloroplasts was lower than in the other variants. The effect of a joint treatment of KIN and IAA did not exceed that of KIN (10^-5M) alone. Thus the development of chloroplasts and the accumulation of chlorophyll in wheat coleoptiles are stimulated by the concentration of KIN which does not promote the elongation of coleoptiles.     

Rapid,nondestructive measurement of chlorophyll content in leaves with nonuniform chlorophyll distribution

A practical microcomputerized video image analysis method is described for quantifying leaf chlorophyll content without extraction. Chlorophyll concentration is estimated from densimetric measurements of whole, intact leaves. Direct comparison with conventional extraction measurements on Epipremnum aureum, a variegated species, verified the image analysis technique's accuracy. The inherent advantages with regard to the nondestructive and convenient nature of the measurement, and suitability for leaves with irregular chlorophyll distribution, are discussed.     

Involvement of chlorophyllase in chlorophyll metabolism in olive varieties with high and low chlorophyll content

Olive fruits of the Arbequina variety are differentiated from those of Hojiblanca and Picual by the differing presence of 13²-OH-chlorophyll a and of dephytylated chlorophyll derivatives during the life cycle of the fruit. During the fruit growth stage, which coincides with chlorophyll synthesis, chlorophyllase (EC: 3.1.1.14) is present in the three varieties but only yields chlorophyllides in Arbequina. The presence of oxidized catabolites of chlorophyll a in fruits of the Arbequina variety during this same period confirms the activity of oxidative enzyme systems. The low synthesis of chlorophylls in the fruits of the Arbequina variety is associated with the fact that, during the natural biosynthetic turnover, the catabolic pathway is more potentiated than the anabolic one. In the ripening phase, in the Hojiblanca and Picual fruits, chlorophyllase activity was measured but the absence of chlorophyllides showed that this enzyme remains latent and that oxidative enzymes are the ones taking part in the chlorophyll disappearance. In the Arbequina variety, both chlorophyllase and oxidative enzymes are responsible for the chlorophyll degradation.     

遮光处理对不同生育期小麦生物量分配和叶片叶绿素含量的影响

以普通小麦'扬麦12号'(Triticum aestivum 'Yangmai 12') 为实验材料,研究了遮光处理对不同生育期小麦生物量分配和叶片叶绿素含量的影响.结果显示,从拔节期到完熟期,在不同遮光条件下(对照:相对透光率为100%;T1:相对透光率约为80%;T2:相对透光率约为60%;T3:相对透光率约为20%),小麦地上部分、地下部分及全株干质量随着发育期的延续总体呈增加趋势.遮光处理使小麦地上部分和地下部分干质量较对照不同程度降低,其中遮光对地上部分干质量的影响大于地下部分,并且根冠比随遮光程度的增加而增大.从开花期开始,各个生育期T3处理组小麦的根冠比均为最大,对照组小麦的根冠比均为最小.'扬麦12号'地上部分和地下部分异速生长关系为简单的线性异速生长模型,遮光后小麦的异速性减小,按小麦地上部分和地下部分间的异速性由大至小依次排序为对照组、T1处理组、T2处理组、T3处理组.从抽穗期到乳熟期,对照及各处理组小麦叶片的叶绿素a、叶绿素b及总叶绿素含量在灌浆期(或乳熟期)最高;在不同的生育期,不同遮光处理对小麦叶片中叶绿素a、叶绿素b及总叶绿素含量的影响不同,随着遮光程度的增加,各遮光处理组小麦的叶绿素a/b均不同程度低于对照.     

Influence of different sized Daphnia species on chlorophyll concentration and summer phytoplankton community structure in eutrophic Wisconsin lakes

We conducted field observations on 13 eutrophic Wisconsin lakesdominated by either the larger bodied Daphnia pulicaria or thesmaller bodied Daphnia galeata mendotae. While Daphnia numericaldensities were not significantly different between groups oflakes, pulicaria lakes had much higher Daphnia biomasses andfiltration potentials than galeata lakes. Although we foundsignificant differences in chlorophyll (Chl) a between bothgroups of lakes during June, on a seasonal basis populationsof different sized Daphnia were not associated with significantdifferences in Chl a. Filtration potential per se was the majordeterminant of Chl a, regardless of which Daphnia species dominated.However, in pulicaria lakes, the clear-water phase started earlier,lasted longer, and was usually characterized by greater Secchidisc readings than in galeata lakes. For large blue-green algaesuch as Aphanizomenon, D.pulicaria appeared to delay bloom conditions,but ultimately did not prevent the alga from growing. Our resultssuggest that high densities of large-sized Daphnia are a desirablegoal of biomanipulation because they can attain filtration potentialshigh enough to increase summer water clarity in eutrophic lakes.     

Water content of chlorophyll hydrate

Thermogravimetry shows that polycrystalline chlorophyll a is a chlorophyll dihydrate. Neither thermogravimetry nor differential thermal analysis indicates the existence of a stable chl a monohydrate. Moreover it is found that larger amounts of water-free chlorophyll a (>50 mg) cannot be prepared by application of vacuum and heat in a reasonable time, if chemical decomposition is to be avoided. Thin layers of polycrystalline chlorophyll a undergo spectroscopic changes depending on temperature and vacuum.     

Estimation of the chlorophyll content and yield of grain crops via their chlorophyll potential

The results of the assessment of the relationship between the chlorophyll content, crop yield and chlorophyll potential of crops of wheat, barley, and oat are presented. The results of a ground-based remotesensing technique and laboratory data were used to accomplish this assessment. The spectral reflectance data of agricultural crops obtained using a ground-based remote-sensing technique in the Krasnoyarsk region were used to calculate the chlorophyll potential. Long-standing experiments have been carried out in different seasons, under various lighting conditions. Spectral measurements were performed using a double-beam spectroradiometer, which was installed on a mobile work platform at a height from 5 to 18 m. A good correlation between the chlorophyll content, grain yield, and chlorophyll potential of different cultivars of wheat, barley, and oat has been shown. It was also shown that the values of chlorophyll potential are different for wheat, barley, and oat cultivars in the growing season.     

The presence of chlorophyll b and the estimation of phaeopigments in marine phytoplankton

A reverse-phase h.p.l.c. technique was used to estimate theconcentration of chlorophyll b in phytoplankton cultures, fecalpellets of Calanus pacificus, and suspended paniculate matterfrom the Central North Pacific, Oregon coastal waters, and DabobBay (a temperate fjord in Puget Sound, WA, USA). The purposewas to assess the distribution of this pigment in the euphoticzone and its effect on the fluorometnc estimation of phaeopigments.Analyses of natural waters confirm high chlorophyll b concentrations(median mass ratio of b:a > 0.3) at the depth of the chlorophylla maximum in tropical waters while values for temperate planktonare relatively low (median mass ratio of chl b:a = 0.05) andpatchy. Zooplankton fecal pellets showed a significant enrichmentin chlorophyll b, suggesting grazing as a mechanism to explainhigh concentrations of this pigment at the bottom of the euphoticzone. It is estimated that the presence of chlorophyll b couldcause an average overestimation of phaeopigment concentrationby the fluorometnc technique of 38% between 0 and 200 m in theCentral North Pacific. This effect is more pronounced at thelayer of chlorophyll b maximum (120–140 m). ¹Present address: Marine Biology Research Division, A-002, ScrippsInstitution of Oceanography, La Jolla, CA 92093, USA     

水色及其与藻类的关系

水色是水环境质量评价中一个重要的综合性指标,不同的水色反映水质的营养状况;藻类群落是水体营养状况的生物表征,对水色具有重要影响作用。本文通过分析不同水色中的藻类优势种群及其作用,认为藻类优势种群是决定水色的主要生物因子;阐明了藻类与水色之间的相互关系以及施肥改变水色的内在机理,水体营养状况决定了水体藻类群落结构进而决定不同的水色;并结合实践对如何判断不同藻类种群引起的不同水色提出了看法,同时对改变和调控水色的方法和途径进行了论述,为相关生产和水环境管理提供理论依据和技术指导。     

浮游植物中叶绿素a提取方法的比较与改进

对水质监测中叶绿素a的提取方法进行改进,采用反复冻融-浸提方法提取叶绿素a,即将过滤水样的滤膜于-20℃冰箱内和室温下反复冻融3～5次后,放进90%丙酮溶液中浸提20h。与标准方法中的研磨法对比,该方法具有人为误差小、稳定性好、结果准确及操作简单安全等优点,适合运用于常规的水质监测。采用该方法时过滤水量对湖水水样的测定结果有影响(P<0.01),对于纯微囊藻液影响不明显(P>0.05)。因此,在对不同叶绿素水平或营养水平的水体采样时,应注意水样的水量。通过方差分析表明该方法中采用醋酸纤维滤膜、微孔滤膜和玻璃纤维滤膜对结果没有显著影响,对这3种滤膜可以进行自由选择。