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C. Steven Sikes 《Journal of phycology》1978,14(3):325-329
Clacium sorption by Cladophora glomerata (L.) Kutz grown in continuous-flow culture increased substantially as the alga aged (12.3–160 mg Calg dry wt). This reflected increased pectin layered in thickening cell walls followed by deposition of CaCO3 around cells. The high levels of pectin (up to 23% of dry wt) may account for the plant's reported high affinity for cations. The onset of carbonate deposition coincided with the appearance of carbonabic anhydrase activity in cells. This suggests that carbonate deposition mey be a funtion of bicarbonate use as a source of CO2 for photosynthesis. Calcium uptake appears to occur by active transport in that it exhibited saturation kinetics, occurred against a concentration gradient, depended on light, and was nearly abolished by treatments that allow diffusion. Although strontium competed for Ca for binding sites of pectin, it did not inhibit intermal transport of Ca. Consequently, the proposed carrier may be specific for Ca. 相似文献
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Primary production rates of edaphic algae associated with the sediments beneath four monospecific canopies of vascular plants were determined over an annual cycle in a Mississippi salt marsh. The edaphic algal flora was dominated by small, motile pennate diatoms. Algal production (as measured by 14C uptake) was generally highest in spring-early summer and lowest in fall. Hourly rates ranged from a low of 1.4 mg C/m2 in Juncus roemerianus Scheele to a high of 163 mg C/m2 beneath the Scirpus olneyi gray canopy. Stepwise multiple regressions identified a soil moisture index and chlorophyll a as the best environmental predictors of hourly production; light energy reaching the marsh surface and sediment and air temperature proved of little value. Adding the relative abundances of 33 diatom taxa to the set of independent variables only slightly increased R2; however, virtually all variables selected were diatom taxa. R2 was only 0.38 for the Spartina alterniflora Loisel. habitat but ranged from 0.70 to 0.87 for the remaining three vascular plant zones. Annual rates of algal production (g C/m2) were estimated as follows: Juncus (28), Spartina (57), Distichlis spicata (L.) Greene (88), and Scirpus (151). The ratio of annual edaphic algal production to vascular plant net aerial production (EAP / VPP) was 10–12% for the first three habitats and 61% for Scirpus. Chlorophyll a concentrations, annual algal production rates, and EAP / VPP values were comparable to those determined in Texas, Delaware, and Massachusetts salt marshes but lower than those reported for Georgia and particularly California marshes. 相似文献
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Xavier Pochon Michael Stat Misaki Takabayashi Luis Chasqui Leonard J. Chauka Daniel D. K. Logan Ruth D. Gates 《Journal of phycology》2010,46(1):53-65
Many scleractinian corals must acquire their endosymbiotic dinoflagellates (genus Symbiodinium) anew each generation from environmental pools, and exchange between endosymbiotic and environmental pools of Symbiodinium (reef waters and sediments) has been proposed as a mechanism for optimizing coral physiology in the face of environmental change. Our understanding of the diversity of Symbiodinium spp. in environmental pools is poor by comparison to that engaged in endosymbiosis, which reflects the challenges of visualizing the genus against the backdrop of the complex and diverse micro‐eukaryotic communities found free‐living in the environment. Here, the molecular diversity of Symbiodinium living in the waters and sediments of a reef near Coconut Island, O‘ahu, Hawai‘i, sampled at four hourly intervals over a period of 5 d was characterized using a Symbiodinium‐specific hypervariable region of the chloroplast 23S. A comparison of Symbiodinium spp. diversity recovered from environmental samples with the endosymbiotic diversity in coral species that dominate the adjacent reef revealed limited overlap between these communities. These data suggest that the potential for infection, exchange, and/or repopulation of corals with Symbiodinium derived from the environment is limited at this location, a finding that is perhaps consistent with the high proportion of coral species in this geographic region that transmit endosymbionts from generation to generation. 相似文献
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Eutrophication of coastal waters often leads to excessive growth of microalgal epiphytes attached to seagrass leaves; however, the effect of increased nutrient levels on sediment microalgae has not been studied within seagrass communities. A slow‐release NPK Osmocote fertilizer was added to sediments within and outside beds of the shoal grass Halodule wrightii, in Big Lagoon, Perdido Key, Florida. Gross primary production (GPP) and biomass (HPLC photopigments) of sediment microalgae within and adjacent to fertilized and control H. wrightii beds were measured following two 4‐week enrichment periods during June and July 2004. There was no effect of position on sediment microalgal GPP or biomass in control and enriched plots. However, nutrient enrichment significantly increased GPP in both June and July. These results suggest that sediment microalgae could fill some of the void in primary production where seagrass beds disappear due to excessive nutrient enrichment. Sedimentary chl a (proxy of total microalgal biomass) significantly increased only during the June enrichment period, whereas fucoxanthin (proxy of total diatom biomass) was not increased by nutrient enrichment even though its concentration doubled in the enriched plots in June. 相似文献
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Erik T. Buitenhuis Hein J. W. de Baar Marcel J. W. Veldhuis 《Journal of phycology》1999,35(5):949-959
To test the possibility of inorganic carbon limitation of the marine unicellular alga Emiliania huxleyi (Lohmann) Hay and Mohler, its carbon acquisition was measured as a function of the different chemical species of inorganic carbon present in the medium. Because these different species are interdependent and covary in any experiment in which the speciation is changed, a set of experiments was performed to produce a multidimensional carbon uptake scheme for photosynthesis and calcification. This scheme shows that CO2 that is used for photosynthesis comes from two sources. The CO2 in seawater supports a modest rate of photosynthesis. The HCO is the major substrate for photosynthesis by intracellular production of CO2 (HCO+ H+→ CO2+ H2O → CH2O + O2). This use of HCO is possible because of the simultaneous calcification using a second HCO, which provides the required proton (HCO+ Ca2+→ CaCO3+ H+). The HCO is the only substrate for calcification. By distinguishing the two sources of CO2 used in photosynthesis, it was shown that E. huxleyi has a K½ for external CO2 of “only” 1.9 ± 0.5 μM (and a Vmax of 2.4 ± 0.1 pmol·cell−1·d−1). Thus, in seawater that is in equilibrium with the atmosphere ([CO2]= 14 μM, [HCO]= 1920 μM, at fCO2= 360 μatm, pH = 8, T = 15° C), photosynthesis is 90% saturated with external CO2. Under the same conditions, the rate of photosynthesis is doubled by the calcification route of CO2 supply (from 2.1 to 4.5 pmol·cell−1·d−1). However, photosynthesis is not fully saturated, as calcification has a K½ for HCO of 3256 ± 1402 μM and a Vmax of 6.4 ± 1.8 pmol·cell−1·d−1. The H+ that is produced during calcification is used with an efficiency of 0.97 ± 0.08, leading to the conclusion that it is used intracellularly. A maximum efficiency of 0.88 can be expected, as NO uptake generates a H+ sink (OH− source) for the cell. The success of E. huxleyi as a coccolithophorid may be related to the efficient coupling between H+ generation in calcification and CO2 fixation in photosynthesis. 相似文献
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根据lhm2的热带山地雨林固定样地连续观测资料,利用生物量估测的回归模型,计算了林分的生物现存量及生物量净增量,结果表明,保存完好的尖峰岭热带山地雨林的生物量(以1992年野外资料为基础)达449.8924thm-2,其中,树干、树皮、树枝、树叶、树根分别为301.9203、30.7921、46.7583、6.5907、30.9169thm-2;棕榈科的高山蒲葵为1.2257thm-2;木质藤本植物1.2375thm-2;548天(1.5014年)后进行样地复查,上述各项值均有所增加,其净增量分别为7.2374、0.7519、1.1611、0.1743、0.8071、0.1568、0.0208thm-2,其年平均净积累量为4.8205、0.5008、0.7734、0.1161、0.5376、0.1044、0.0685thm-2,因此总积累达7.3590thm-2,由此推算出CO2同化量的净积累为13.9947thm-2a-1,而林分的CO2库存总量为850~870thm-2。 相似文献
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In situ 14C uptake (dawn to dusk) and fast repetition rate fluorometry (FRRF) measurements at nearly monthly intervals were compared at Station ALOHA (22°45′N, 158°00′W) between August 2002 and September 2003 in order to determine the feasibility of using FRRF profiling as a means for estimating primary production (PP). The FRRF and 14C rates were significantly correlated (r2=0.906, P value <0.05, n=70) with slopes of 2.00 and 1.90 for chl a and light normalized data, respectively. However, the relationship between 14C‐ and FRRF‐derived carbon fixation varied vertically and temporally. The FRRF: 14C ratio was >1.5 in near‐surface water (5–25 m depth) and approached 1.0 deeper in the euphotic zone. Vertical variations probably reflected the effect of different physiological processes (i.e. Mehler reaction, dark respiration, and excretion) on overall photoautotrophic respiration. In particular, the decrease in Mehler reaction rates with increasing water depth may have accounted for the decrease in difference between 14C and FRRF measurements with depth. The influence of in situ light field variability in controlling the absorption cross‐section of photosystem II (PSII) (σPSII′) may also have been responsible for some of this difference. When compared with total community respiration (R), the derived light‐driven photoautotrophic respiration (reported here as the difference between FRRF and 14C measurements) represented approximately 50% of R integrated over the euphotic zone. Our results show that FRRF and 14C measurements were well correlated in oligotrophic waters but the exact relationship between the two processes varies both temporally and vertically, such that a unique relationship between these two techniques could not be derived from first‐order principles. 相似文献
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该文利用涡度协方差法和生理生态学方法(不同分量的累积和)获得的通量观测数据,对老山落叶松(Larix gmelinii)林(45°20′N, 127°34 ′E)的碳收支进行了分析。通过对每0.5 h所测数据进行的分析表明,能量平衡达到75%,说明涡度协方差法适应于本站的研究。较阴天气情况 下,林分光照利用效率显著高于晴朗天气,可能归因于阴天较多的散射光。以单位土地面积计算发现,通过涡度协方差法计算的落叶松林生态 系统的总初级生产力在20~50 μmol•m-2•s-1之间,远高于冠层叶片的总光合速率9.8~23.4μmol•m-2•s-1 (平均值16.2μmol•m-2•s-1 ),而 当综合考虑冠层光合和林下植物光合作用时,两种方法测定结果吻合性较好,说明林下植物对落叶松林碳平衡有重要影响。在估计森林生态系 统呼吸方面,以有风夜晚净生态系统交换量(NEE)来代表生态系统呼吸总量(3~9μmol•m-2•s-1)低估了生态系统呼吸总量,粗略估计较生 理生态学方法(不同呼吸分量的累积和)低估了50%左右(14.2μmol•m-2•s-1)。结果发现两种方法在估计森林碳平衡方面存在一定的差异, 呼吸量的估计差异应是今后研究的重点。 相似文献
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Shigetoh Miyachi Mikio Tsuzuki Isao Maruyama Miroslav Gantar Shizuko Miyachi Hisashi Matsushima 《Journal of phycology》1986,22(3):313-319
Effects of CO2 concentration during growth on intracellular structure were studied with ftve species of Chlorella and Scenedesmus obliquus. Cells grown under ordinary air conditions (low-CO2 cells) had a well developed pyrenoid surrounded by starch, while those grown under high CO2 conditions (high-CO2 cells) had a less developed pyrenoid or no detectable pyrenoid. Two mitochondria, one at each side of the neck of the projection of the chloroplast close to the pyrenoid, were found in low CO2 cells of C. vulgaris 11h. Usually, lamellar stacks extended in parallel in the chloroplast of low-CO2 cells of C. vulgaris 11h, while a grana-like structure was found in high-CO2 cells. However, in C. pyrenoidosa, grana like structures were found more commonly in low-CO2 cells than in high-CO2 cells. These results suggest that development of pyrenoid starch is generally correlated with growth under low CO2 conditions, whereas CO2-effects on lamellar stacking are species dependent. 相似文献
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Estimates for the production of calcium carbonate by Halimeda spp. have been based on limited measures in small areas or over short periods, subsequently extrapolated over larger temporal and spatial scales. The accuracy of these extrapolations depends on the variations in time and space of the parameters used for the derivations of the production, which were evaluated in the present study for Halimeda incrassata (J. Ellis) J. V. Lamour. in the Puerto Morelos reef lagoon, Mexican Caribbean. Growth, biomass, and CaCO3 content of the branches of the thalli were determined at 1–3 monthly intervals from November 1997 until June 1999, using the marking technique with the coloring agent Alizarin Red‐S. Biomass exhibited great variability (V=25.4%), and fluctuations were closely related to changes in thallus density. Growth and CaCO3‐content changes were related to the solar cycle, having coefficients of 15.4% and 2.5%, respectively. Additionally, calcified biomasses of the thalli were determined over a large spatial (31 stations in ~7 km2 area) and time (6 y) scale. Spatial variability in calcified biomass was 59%, and the coefficient of variation attained its highest value (69%) for the samples collected over a 6 y period, from 1990 to 1996 (except 1995). Based on overall average values, branches of H. incrassata in the study area had a mean turnover of 30 d, with an annual production of 815 g CaCO3 per square meter. 相似文献
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Blade elongation was compared in two populations of Laminaria longicruris de la Pylaie in Shag Bay, Nova Scotia, Canada; one population was exposed to and the other sheltered from high intensity water movement. The maximum and minimum elongation rates were similar for the two populations, but the sheltered coast plants grew more rapidly during 8 mo of the year. Measurements of internal inorganic nitrogen (NO3?+ NO2?) reserves and dry organic weight indicated that low concentrations of dissolved nutrients in summer and low levels of illumination in fall and winter were more limiting to growth at the exposed site than the sheltered site. Transplant experiments provided evidence that morphological differences between the exposed and sheltered coast plants accounted at least partially for their different responses to varying nutrient conditions and light levels. It is concluded that lower productivity of the exposed coast population is the result of adaptation to high intensity water movement. 相似文献
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Chlorella emersonii Shihira et Krauss var. emersonii exhibits ‘C4-like’ gas exchange characteristics when grown at air levels of CO2, but is ‘C3-like’ when grown with extra CO2. The total inorganic carbon concentration, and the free CO2 concentration, averaged over the cell interior are higher in air-adapted cells than can be accounted for by passive CO2 equilibration from the medium and the mean intracellular pH value. The ‘extra’ inorganic C in the air-grown cells probably cannot all be accounted for in terms of binding to proteins and requires an active transport process to account for it. The electrical potential of the cell interior becomes more negative when the ‘CO2 concentrating mechanism’ is operative; this is most readily explained if the active step in inorganic C accumulation is primary active uniport of HCO3?. Since the ‘CO2 concentrating mechanism’ can operate when CO2 is the species crossing the outer permeation barrier, it is suggested that the site of active HCO3? transport in Chlorella (and other eukaryotes) is the chloroplast envelope, and the plasmalemma in cyanobacteria. This scheme explains the obligatory role of the de-repressed carbonic anhydrase in C4-like photosynthesis in algae, but some other data support an explanation of C4-like photosynthesis in terms of special properties of carbonic anhydrase as a carbon donor to RuBP carboxylase-oxygenase. 相似文献
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The combined effects of different light and aqueous CO2 conditions were assessed for the Southern Ocean diatom Proboscia alata (Brightwell) Sundström in laboratory experiments. Selected culture conditions (light and CO2(aq)) were representative for the natural ranges in the modern Southern Ocean. Light conditions were 40 (low) and 240 (high) μmol photons · m?2 · s?1. The three CO2(aq) conditions ranged from 8 to 34 μmol · kg?1 CO2(aq) (equivalent to a pCO2 from 137 to 598 μatm, respectively). Clear morphological changes were induced by these different CO2(aq) conditions. Cells in low [CO2(aq)] formed spirals, while many cells in high [CO2(aq)] disintegrated. Cell size and volume were significantly affected by the different CO2(aq) concentrations. Increasing CO2(aq) concentrations led to an increase in particulate organic carbon concentrations per cell in the high light cultures, with exactly the opposite happening in the low light cultures. However, other parameters measured were not influenced by the range of CO2(aq) treatments. This included growth rates, chlorophyll a concentration and photosynthetic yield (FV/FM). Different light treatments had a large effect on nutrient uptake. High light conditions caused an increased nutrient uptake rate compared to cells grown in low light conditions. Light and CO2 conditions co‐determined in various ways the response of P. alata to changing environmental conditions. Overall P. alata appeared to be well adapted to the natural variability in light availability and CO2(aq) concentration of the modern Southern Ocean. Nevertheless, our results showed that P. alata is susceptible to future changes in inorganic carbon concentrations in the Southern Ocean. 相似文献
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Judith D. L. van Bleijswijk Rob S. Kempers Marcel J. Veldhuis Peter Westbroek 《Journal of phycology》1994,30(2):230-241
Two morphotypes of Emiliania huxleyi (Lohmann 1902) Hay et al. 1967, types A and B, known to be unequally distributed in the oceans, were grown in dilution cultures at a range of photon flux densities (PFDs) (1.5–155 μmol photons·m?2·s?1) and two temperatures (10° and 15° C). Calcite carbon and organic carbon content of the cells as well as instantaneous growth rate, cell size, chlorophyll fluorescence, and light-scatter properties clearly depended on growth conditions and differed considerably for the two morphotypes. The ratio between calcite carbon and organic carbon production showed an optimum of 0.65 in E. huxleyi type A cells at PFD = 17.5. The ratio increased slightly with a temperature increase from 10° to 15°C but remained < 1.0 at both temperatures in light-limited cells. In contrast, calcite carbon production exceeded organic carbon production (ratio: 1.4–2.2) in phosphate-deprived cultures. Emiliania huxleyi type B generally showed a higher calcite carbon/organic carbon ratio than E. huxleyi type A, but the relation with PFD was similar. The content of calcite carbon and organic carbon as well as the instantaneous growth rate, cell size, chlorophyll fluorescence, and light-scatter properties showed large diel variations that were closely related to the division cycle. Our results show the importance of mapping the structure of any sampled cell population with respect to the phase in the cell division cycle, as this largely determines the outcome of not only “per cell” measurements but also short time (less than 24 h) flux measurements. For instance, dark production of calcite by E. huxleyi was negatively affected by cell division. Slowly growing (phosphate-stressed) cultures produced calcite in the light and in the dark. In contrast, rapidly growing cultures at 10°C produced calcite only in the light, whereas in the dark there was a significant loss of calcite due to dissolution. 相似文献
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The short‐term and long‐term effects of elevated CO2 on photosynthesis and respiration were examined in cultures of the marine brown macroalga Hizikia fusiformis (Harv.) Okamura grown under ambient (375 μL · L?1) and elevated (700 μL · L?1) CO2 concentrations and at low and high N availability. Short‐term exposure to CO2 enrichment stimulated photosynthesis, and this stimulation was maintained with prolonged growth at elevated CO2, regardless of the N levels in culture, indicating no down‐regulation of photosynthesis with prolonged growth at elevated CO2. However, the photosynthetic rate of low‐N‐grown H. fusiformis was more responsive to CO2 enrichment than that of high‐N‐grown algae. Elevation of CO2 concentration increased the value of K1/2(Ci) (the half‐saturation constant) for photosynthesis, whereas high N supply lowered it. Neither short‐term nor long‐term CO2 enrichment had inhibitory effects on respiration rate, irrespective of the N supply, under which the algae were grown. Under high‐N growth, the Q10 value of respiration was higher in the elevated‐CO2‐grown algae than the ambient‐CO2‐grown algae. Either short‐ or long‐term exposure to CO2 enrichment decreased respiration as a proportion of gross photosynthesis (Pg) in low‐N‐grown H. fusiformis. It was proposed that in a future world of higher atmospheric CO2 concentration and simultaneous coastal eutrophication, the respiratory carbon flux would be more sensitive to changing temperature. 相似文献
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The low CO2 concentration in seawater poses severe restrictions on photosynthesis, especially on those species with form II RUBISCO. We found that the potentially toxic dinoflagellate Protoceratium reticulatum Clap. et J. Lachm. possesses a form II RUBISCO. To cast some light on the mechanisms this organism undergoes to cope with low CO2 availability, we compared cells grown at atmospheric (370 ppm) and high (5000 ppm) CO2 concentrations, with respect to a number of physiological parameters related to dissolved inorganic carbon (DIC) acquisition and assimilation. The photosynthetic affinity for DIC was about one order of magnitude lower in cells cultivated at high [CO2]. End‐point pH‐drift experiments suggest that P. reticulatum was not able to efficiently use HCO3? under our growth conditions. Only internal carbonic anhydrase (CA) activity was detected, and its activity decreased by about 60% in cells cultured at high [CO2]. Antibodies raised against a variety of algal CAs were used for Western blot analysis: P. reticulatum extracts only cross‐reacted with anti‐ß‐CA sera, and the amount of immunoreactive protein decreased in cells grown at high [CO2]. No pyrenoids were observed under all growth conditions. Our data indicate that P. reticulatum has an inducible carbon‐concentrating mechanism (CCM) that operates in the absence of pyrenoids and with little intracellular CO2 accumulation. Calculations on the impact of the CA activity to photosynthetic growth [CO2] suggest that it is an essential component of the CCM of P. reticulatum and is necessary to sustain the photosynthetic rates observed at ambient CO2. 相似文献
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We describe a procedure for the selection of β-carotenerich mutants of the halotolerant alga Dunaliella bardawil Ben-Amotz & Avron. Under normal growth conditions the isolated mutants had a several-fold higher content of β-carotene than the wild type. Under carotene-induction conditions, the mutants also possessed a higher β-carotene content than the wild type. Both the production rate of phytoene and the conversion rate of phytoene to lycopene and β-carotene were accelerated in the mutants. Cycloheximide, which (in the wild type) inhibits the inductive synthesis of the proteins required for β-carotene production, had a much smaller effect on β-carotene biosynthesis in the mutants. We suggest that the mutants are affected in the regulatory path, which controls the induction of high β-carotene production in Dunaliella. 相似文献
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Po‐Teen Lim Chui‐Pin Leaw Gires Usup Atsushi Kobiyama Kazuhiko Koike Takehiko Ogata 《Journal of phycology》2006,42(4):786-799
The two tropical estuarine dinoflagellates, Alexandrium tamiyavanichii Balech and A. minutum Halim, were used to determine the ecophysiological adaptations in relation to their temperate counterparts. These species are the two main causative organisms responsible for the incidence of paralytic shellfish poisoning (PSP) in Southeast Asia. The effects of light (10, 40, 60, and 100 μmol photons·m?2·s?1) and temperature (15, 20, and 25°C) on the growth, nitrate assimilation, and PST production of these species were investigated in clonal batch cultures over the growth cycle. The growth rates of A. tamiyavanichii and A. minutum increased with increasing temperature and irradiance. The growth of A. tamiyavanichii was depressed at lower temperature (20°C) and irradiance (40 μmol photons·m?2·s?1). Both species showed no net growth at 10 μmol photons·m?2·s?1 and a temperature of 15°C, although cells remained alive. Cellular toxin quotas (Qt) of A. tamiyavanichii and A. minutum varied in the range of 60–180 and 10–42 fmol PST·cell?1, respectively. Toxin production rate, Rtox, increased with elevated light at both 20 and 25°C, with a pronounced effect observed at exponential phase in both species (A. tamiyavanichii, r2=0.95; A. minutum, r2=0.96). Toxin production rate also increased significantly with elevated temperature (P<0.05) for both species examined. We suggest that the ecotypic variations in growth adaptations and toxin production of these Malaysian strains may reveal a unique physiological adaptation of tropical Alexandrium species. 相似文献