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111.
This study presents data of in situ measurements of inorganic carbon assimilation by phytoplankton communities of the St Lawrence estuary during the end of summer 1982. We used carboxylase activity measurements (ribulose-1,5-bisphosphate carboxylase, carboxylases) and the 13C/12C ratio of phytoplankton organic carbon, expressed as 13C, to study patterns of assimilation. Upper estuary phytoplankton communities showed a smaller turn-over rate in carbon assimilation than lower estuary phytoplankton communities. Carbon assimilation was limited by light intensity in the upper estuary and by CO2 availability in the lower estuary. In the St Lawrence estuary, stable carbon isotope ratios of phytoplankton organic carbon seemed to be controlled by inorganic carbon availability rather than by phytoplankton metabolism. 相似文献
112.
Phyto- and bacterioplankton biomass and activity were simultaneously measured during the course of one year in the shallow Créteil Lake (France).Phytoplankton was dominated, during the whole year, by small-sized organisms (10 to 25 µm). Bacteria were in a majority small coccoids (<0.3 µm). Phyto -and bacterioplankton abundances averaged respectively 3.3 × 106 cells l–1 and 6 × 109 cells l–1.The phasing of the activity and biomass periods suggest a close coupling between phyto- and bacterioplankton. There were two distinct periods of high activity and biomass. Maximal values were observed in summer but an early increase occurred also in winter. Low or undetectable phytoplankton excretion rates, when heterotrophic activity was maximum, indicated a bacterial uptake of up to 100% of the released algal products during the incubation period. Heterotrophic uptake measurements with both glucose and amino acids revealed a seasonal change of the substrates in the lake, glucose uptake being associated more with the maximum activity of the algae, while the amino acids uptake was relatively higher during their decline.The maximal photosynthetic rate averaged 21.5 mgC m–3 h–1 and mean Vmax values were 0.056 and 0.050 mgC m–3 h–1 respectively for glucose and amino acids uptake. 相似文献
113.
Seasonal and areal features of the lagoonal environment in Lake Nakanoumi,a shallow coastal lagoon in Japan 总被引:1,自引:1,他引:0
Lake Nakanoumi is a shallow coastal lagoon connected with the Japan Sea by a narrow channel. Over the past decade, land reclamation resulted in a 33% reduction of the lagoon's surface area. The remaining water basin of Lake Nakanoumi is scheduled to be artificially freshened to supply irrigation water for the newly reclaimed lands. This paper deals with the seasonal and areal features of the lagoonal environment prior to the beginning of the artificial desalinization. 相似文献
114.
Gertrud Cronberg 《Hydrobiologia》1982,86(1-2):185-193
Lake Trummen, previously an oligotrophic lake, was heavily polluted during 1930–1957. The lake was restored by suction dredging of the top sediment layer. After restoration nutrien concentrations and phytoplankton biomass were drastically reduced. Eutrophic species disappeared and more oligotrophic species returned to the lake. The investigation covers 12 years-monthly-bimonthly countings of algae together with electronmicroscopical studies of taxonomically difficult taxa. The investigation was made at the species level (300 species identified and 80 quantitatively recorded). 相似文献
115.
Stephen S. Bates Andr Tessier Peter G. C. Campbell Jacques Buffle 《Journal of phycology》1982,18(4):521-529
The amount of zinc adsorbed onto the cell surface of the unicellular green algae Scenedesmus subspicatus Hodat and Chlamydomonas variabilis Dangeard was operationally defined by extraction with EDTA; it was a function of the concentration of free ionic zinc remaining in the growth medium, rather than that of the total (free plus complexed) zinc concentration, and could be described by Langmuir isotherms. Conditional adsorption equilibrium constants for zinc were 0.123 and 0.039 L ·μmol?1 for S. subspicatus and C. variabilis, respectively. A portion of the zinc adsorbed onto C. variabilis was released into solution after 1 h of contact with the metal, providing a possible tolerance mechanism for this alga; the division rate of C. variabilis was not altered by up to 12 μmol Zn2+· L?1, although the cell yield obtained during the stationary phase was significantly decreased. The amount of transported or cellular zinc, for both algal species, was operationally defined as the zinc remaining with the cell after EDTA-extraction; it was a linear function of the free ionic zinc concentration remaining in solution, suggesting that the zinc transported into the cell was not derived from the total adsorbed fraction, although the latter may contain some zinc originating from specific sites leading to zinc transport. 相似文献
116.
The lipid content of various phytoplankton species was measured in response to nitrogen and silicon limitation and over the cell cycle in synchronized cultures. In a survey of 30 species it was found that during log-phase growth, green algae contained an average of 17.1% total lipids (% of total dry weight), whereas diatoms contained an average of 24.5%. Nitrogen deprivation for 4 to 9 days resulted in 2- to 3-fold increases in the lipid content of green algae, whereas both increases and decreases were noted in diatoms, depending on the species. The greatest lipid content measured in the study was 72% in Monallantus salina (strain GSB Sticho) which had been deprived of nitrogen for 9 days. Nitrate replenishment in a nitrogen starved culture of Oocystis polymorpha Groover & Bold showed that the excess cellular lipids do not rapidly disappear during recovery, until cell division occurs. A silicate deprivation experiment with Cyclotella cryptica Reimann, Lewin & Guillard (strain 7c) showed an increase in the total cellular lipid fraction from. 30 to 42% of dry weight within 6 h of the onset of silicon limitation, while the mass of lipid material per cell doubled within 12 h. The total lipid fraction in O. polymorpha was found to remain constant over the cell cycle in synchronized cultures regardless of the light regime. The data presented provided the first internally consistent study of phytoplankton lipids for a wide range of species and several growth conditions. 相似文献
117.
Light-limited rates of photosynthesis normalized for chlorophyll a, (α), and actual photon absorption (quantum efficiency, Ф) were determined for six eponentially growing algal species grown under identical conditions. The same parameters, α and Ф, were also monitored for a single diatom species, Thalassiosira pseudonana Hasle & Heimdal, through its growth cycle in batch culture. Statistical differences in α could be demonstrated among the six different exponentially growing species while no differences could be shown for Ф. Statistical differences among the six species were minimized when photosynthetic rates were normalized for in vivo fluorescence rather than extracted chlorophyll a. Both α and Ф were constant while T. pseudonana was in the exponential phase of growth, but both declined as the culture entered stationary phase. While cells were in exponential growth, differences in a were attributed to varying rates of in vivo light absorption per chlorophyll a, thus providing experimental evidence that the in vivo chlorophyll a extinction coefficient, kc (m2· mg Chl a?1), cannot be assumed constant. 相似文献
118.
Timo Kairesalo 《Journal of phycology》1980,16(1):57-62
The photosynthetic activity of different algal communities at the outer edge of an Equisetum fluviatile L. stand in an oligotrophic lake (Pääjärvi, in southern Finland) was investigated. Production by the algal communities was measured simultaneously using a modified 14C-method, and the results were related to the volume of algae and the available irradiance. The relative production rate (P/B quotient) of phytoplankton was ca. 3 × that of epiphyton and ca. 20 × that of epipelon. Epiphyton productivity remained almost constant although the algal volume varied greatly, suggesting that the surface layer of the algal community was mainly responsible for the photosynthetic activity. In the littoral area (at 1 m depth) primary production/m2 of lake surface by phytoplankton, epiphyton and epipelon was similar but in the littoriprofundal area (2–4 m) phytoplankton production was twice that of epipelon. Primary productivity of epiphyton and epipelon/m2 of substratum was about equal to phytoplankton productivity/m3 of water at the same irradiance. This relation provided a means of estimating the relative contributions of the different algal communities to the total algal production in the lake. 相似文献
119.
Christian Amblard 《Hydrobiologia》1981,85(3):257-270
A study on A.T.P., A.D.P. and A.M.P. in the phytoplankton of Lake Pavin was carried out from November 1976 to December 1977. Samples were collected at nine depths, between the surface and 50 m.A.T.P., A.D.P. and ( = A.T.P.+ A.D.P. + A.M.P.) show a similar behaviour in space and time but A.M.P. behaves independently. The A.M.P. concentration is high only when primary production of phytoplankton is high.The energy charge [CE = (ATP + % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSGaaeaaca% aIXaaabaGaaGOmaaaaaaa!3776!\[{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$2$}}\]ADP)/(ATP + ADP + AMP)] could be used as measure of adaptation in algal populations. Indeed, the energy charge increases as algal cells experience difficulty in maintaining themselves in the biotope.
Interêts du dosage des adénosines 5-phosphate pour l'étude de la dynamique des populations phytoplanctoniques lacustres (le Pavin - France)相似文献
120.
Yasuhiro Satoh 《Hydrobiologia》1981,83(1):153-160
Free bacterial populations were separated from an intact planktonic community in water of a eutrophic reservoir in Japan by filtration through Whatman GF/ C glass fiber filters (mean porosity 1.2 µm). Urea decomposition by the free bacterial populations and the intact planktonic community was determined in six different months.The separated free bacteria apparently did not take part in urea-decomposition in waters of the reservoir through the year: the number of free heterotrophic bacteria increased during the urea-decomposition experiments, however, the concentration of urea did not decrease. Whereas, in five cases out of six, urea was decomposed by the intact planktonic community. Probably, phytoplankton were responsible for most of the urea-decomposition. On the assumption that the decomposition of urea obeyed first-order kinetics, rate constants were calculated to be 0.00–0.63 day–1 with a mean value of 0.21 day–1. 相似文献