摘要:

ABSTRACTVariations in tissue nitrogen (N) and phosphorus (P) were examined over a complete seasonal cycle for five macroalgae common in Oregon coastal water. Tissue N ranged from 2.0 to 5.5% dry weight (dry wt) in leafy macroalgae (Enteromorpha intestinalis(Linnaeus) Link.Ulva fenestrataPostels et Ruprecht, andPorphyrasp.) and from 0.9 to 2.6% drt wt in branched macroalgae(Codium fragile(Suringar) Hariot andPelvetiopsis limitataSetchell). Tissue P ranged from 0.32 to 0.86% dry wt in leafy macroalgae and from 0.27 to 0.50% dry wt in branched macroalgae,Ulva fenestrata, C. fragile, andP. limitataappeared to be N limited during part of the year based on tissue N levels. Variations in N:P showed a more distinct seasonal pattern than either tissue N and tissue P. All macroalgae examined appeared to be N limited at least part of the year based on N:P composition, and P limitation occurred for all macroalgae examined exceptC. fragile.Our results suggest that tissue N:P ratio for macroalgae may be a good index for evaluatingin situnutrient status.

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1992.00001.x

出版商:Blackwell Science Inc    

年代:1992

数据来源: WILEY

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1992.00003.x

出版商:Blackwell Science Inc    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTThis study was designed to understand the high variability characterizing primary production rates of microphytobenthos. The photosynthetic efficiency (αB) and photosynthetic capacity (PBmax) of the microphytobenthos were measured at different times of the day on two different dates (8 May and 7 July 1990). In July, unusually low light conditions were caused by the development of a brown tide (chrysophytes). Both light‐limited and light‐saturated photosynthesis changed at hourly and monthly scales. There was a linear relationship between αBand PBmax, suggesting a common response to environmental factors [αB= 0.0075(±0.00063)·PBmax+ 0.00097(±0.0071),R2=0.94]. Incident irradiance at the sediment‐water interface was the primary physical factor that explained variability of both αB(84%) and PBmax(92%). Temperature had a negative but minor effect that explained an extra 8% and 2% of the variance, respectively. There was no diel rhythm of αBand PBmaxand incident irradiance was regulated by wind‐induced currents. Therefore, microphytobenthos photosynthesis seemed to be primarily controlled by wind event

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1992.00007.x

出版商:Blackwell Science Inc    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTThe small (<15 μm) hypnozygote of an autotrophic athecate dinofiagellate found in association with Antarctic sea ice had an external covering composed of approximately 60 plates, each of which was bounded by sutural ridging and possessed an intratabular process. A cingulum and sulcus were also evident. The ultrastructure of the cyst was increasingly dominated by storage bodies as the cyst matured, and the cell wall thickened from 0.2 to 0.8 μm over 2 months. This cyst has been encountered often but usually at low abundances (103−104cells·L−1); however, the maximum abundances observed (106cells·L−1) indicate that the formation of this cyst may play an important part in the ecology of sea ice co

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1992.00015.x

出版商:Blackwell Science Inc    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTThe effects of the triazine herbicide, simazine, on photosynthetic oxygen evolution and growth rate in photoacclimated populations ofAnabaena circinalisRabenhorst were investigated. Chemostat populations were acclimated to photon flux densities (PFDs) of 50, 130, and 230 μmol·m−2·s−1of photosynthetic active radiation (PAR), Decreases in chlorophylla (Chla).c‐phycocyanin (CPC), and total carotenoid (TCar) contents and CPC: Chlaand CPC: TCar ratios of populations coincided with increasing PFD, Polynomial regression models that characterize inhibition of photosynthesis for populations acclimated to 50 and 130 μmol photons·m−2·s−1PAR were distinct from the model for populations acclimated to 230 μmol photons·m−2·s−1PAR. Simazine concentrations that, depressed oxygen evolution 50% compared to controls decreased with increasing PFD. Increases and decreases in both biomass and growth rate coincided with increasing PFD and simazine concentration, respectively. Simazine concentrations that depressed growth rate 50% compared to controls increased with decreasing PFD. The differences in photosynthetic and growth inhibition among photoacclimated populations indicate that sensitivity to photosystem II inhibitors is affected by alteratio

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1992.00019.x

出版商:Blackwell Science Inc    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTPhotosynthetic pigments of the green flagellatePseudoscourfieldia marina(Throndsen) Manton (Micromonadophyceae) are similar to those of the coccoidPycnococcus provasoliiGuillard; prasinoxanthin is the predominant carotenoid. Other organisms that possess prasinoxanthin also possess additional pigments not found in eitherP. marinaorP. provasolii.Uriolide, a xanthophyll previously described from the coccoid done URI 266G, was also found inMantoniella squamata(Manton et Parke) Desikachary,Micromonas pusillaManton et Parke andMamiella gilva(Parks et Rayns) Moestrup, all flagellate members of the Mamiellales, and the coccoid clone IV E5G. Other unidentified carotenoids were also present inM. squamata, M. pusilla, andM. gilva.These results suggest thatP. marinaand the coccoid organisms URI 266G and IV E5G may be related to the Mamiellales, and thatP. provasoliimay be more closely related toP. marinathan toM. squamata, M. pusilla, andM. gilva.

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1992.00026.x

出版商:Blackwell Science Inc    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTPigment‐protein complexes were isolated from two species of Eustigmatophyceae,Monodus subterraneusPeterson andVischeria punctataVischer, by digitonin treatment followed by density gradient centrifugation. Absorption and fluorescence spectra of the samples were monitored at various steps of preparation, and pigment composition was analyzed by reverse phase HPLC. Although the fluorescence emission spectra were very different in the two species, the absorption spectra were similar, and each exhibited an absorption band with a maximum at 487 nm attributable to violaxanthin and vaucheriaxanthin ester (the molar concentration of these pigments inMonoduswas, respectively, 28 and 10 per 100 Chl a). The light‐harvesting role of these xanthophylls was ascertained by fluorescence excitation spectra. The light‐harvesting fractions (LH) collected in the upper part of the gradient were depleted in β‐carotene, whereas their xanthophyll/chlorophyll ratio was almost the same as in whole cells. This is consistent with the presence in these algae of large LH antennae and relatively small core antennae in the photosystems. InMonodus, a polypeptide of 23 kDa, immunologically related to the major LH polypeptide of brown algae, constituted the majority of the LH protei

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1992.00032.x

出版商:Blackwell Science Inc    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTFatty acid (FA), total lipid, protein, amino acid, carbon, nitrogen, and phosphorus content was analyzed in 24 samples of freshwater microalgae. The samples originated from batch, continuous, or mass cultures in various growth phases and from net samples from lakewater. FA were analyzed quantitatively by using an internal standard in a GLC system and expressed as mg·g−1dry weight (DW). The FA of one group of blue‐greens (e.g.OscillatoriaandMicrocystis)were similar to those of the greens with higher amounts of 18C acids of the ω3 type compared to the ω6 type, whereas the other group (e.g.AnabaenaandSpirulina)contained mostly ω6 acids. The flagellates, a taxonomically diverse group, were characterized by high amounts of long‐chained (20–22 C) polyunsaturatedFA (PUFA), particularly of the ω3 type. The ω3/ω6 ratio appears to be highest in algae in the exponential growth phase. The increased lipid content in stressed algae was mostly due to increased saturated fatty acids and ω6 acids, whereas the valuable ω3 acids were unchanged or even decreased.Amino acid composition (% of total amino acids) did not vary much betaken species, but when analyzed quantitatively (mg‐g−1DW), varied considerably between species and within species in different growth phases. The nitrogen and phosphorus contents were variable in all three algal groups. The relationship between PUFA and phosphorus content differed among the algal groups. The data suggest that PUFA in the phospholipids con

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1992.00037.x

出版商:Blackwell Science Inc    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTPhotosynthesis and respiration were analyzed in natural biofilms by use of O2microsensors. Depth profiles of gross photosynthesis were obtained from the rate of decrease in O2concentration during the first few seconds following extinction of light, and net photosynthesis of the photic zone was calculated from O2concentration gradients measured at steady state. Respiration within the photic zone was calculated as the difference between gross and net photosynthesis. Two types of biofilms were investigated: one dominated by diatoms, and one dominated by cyanobacteria. High O2/CO2ratios caused increased respiration especially within the diatom biofilm, which could indicate that photorespiration was a dominant O2‐consuming process. The rate of respiration was constant within both biofilms during the first 4.6 s following extinction of light, even when respiration was stimulated by high O2/CO2ratio. The assumption of a constant rate of respiration during the dark period is an essential one for the determination of gross photosynthetic activity by use of O2microsensors. We here present the first evidence to substantiate this assumption. The results strongly suggest that gross photosynthesis as measured by use of O2microsensors may include carbon equivalents that are subsequently lost through photorespiration. Computer modeling of photosynthesis profiles measured after 1.1, 1.6, and 2.6 s of dark incubation illustrated how the actual photosynthesis profile could have appeared if it had been possible to do the determination at time 0. Diffusion of O2during the up to 4.6‐s long dark incubations did not affect gross photosynthetic rate when integrated over all depths, but the apparent vertical distribution of the photosynthetic activity was strongly affec

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1992.00051.x

出版商:Blackwell Science Inc    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTThe Hindak strain of aCryptomonasspecies (Cryptophyceae) produces extracellular polysaccharides. Because there is no information on the structure of these compounds in the Cryptophyceae we conducted structural studies. Gas–liquid chromatographic analyses showed that the polysaccharide is composed of fucose, rhamnose, xylose, mannose, glucose, galactose, galacturonic acid, glucuronic acid, and traces of 3‐O‐methyl galactose. The polysaccharide was separated into two subtractions by ion‐exchange chromatography. Fraction A consisted mainly of 1,3‐linked galactose units and 1,4‐linked galacturonic acid. Unlike fraction B, fraction A did not have xylose, 3‐O‐methyl galactose, or glucuronic acid. Also, its degree of branching was low compared to that of fraction B. Only traces of sulfate were present infraction A, but fraction B was 10–15% sulfated. Protein was approximately 1% in both fractions. These polysaccharides appear to be a novel type of

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1992.00061.x

出版商:Blackwell Science Inc    

年代:1992

数据来源: WILEY