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81.
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
82.
Magnus Enell 《Hydrobiologia》1982,86(1-2):153-158
The phosphorus dynamics and economy of Lake Bysjön, a hypertrophic seepage lake in Scania, southern Sweden, were investigated during 1973–1977. The mean dissolved inorganic phosphorus concentration (1973–1977) was 580 µg · l–1. There were no correlations between dissolved inorganic P, total organic P, dissolved organic P, particulate P and phytoplankton biomass. Groundwater inflow and lake water outflow through the ground are the most important factors for maintaining a constant water volume. Groundwater seepage is also important for water quality. Groundwater inflow, together with planktonic activity, keeps the P concentration high in the lake water. 相似文献
83.
The recovery of L. Vesijärvi following sewage diversion 总被引:2,自引:2,他引:0
Juha Keto 《Hydrobiologia》1982,86(1-2):195-199
For 60 years the sewage of the City of Lahti was discharged into L. Vesijärvi. The eutrophication of the lake was observed as early as the 1920s but in the 1960s the pollution became obvious. The sewage was completely diverted in 1976. As a result of the diversion the bacteriological defects were eliminated within one year, restoring the recreational value of the lake. The recovery of water quality was rapid during the first two years. The oxygen content increased markedly but hypolimnetic oxygen depletion persisted. The phosphorus content decreased about 60% and the nitrogen content about 30%. After that period the recovery slowed down. The biomass of phytoplankton decreased but the abundance of heterocystous blue green algae increased causing blooms in July and August. The primary production has lately been reduced despite the lack of improvement in chemical water quality. Hypolimnetic aeration was started in order to accelerate the recovery. The results during winter stagnation have been encouraging. 相似文献
84.
A study on biological activity measurements and heterotrophic bacteria in a small freshwater lake 总被引:1,自引:1,他引:0
A 6-m-deep lake has been sampled to measure the temporal and depth-wise distribution of heterotrophic bacteria and biological activity in the water. Surface, mid-depth and bottom waters were analysed at monthly intervals for a period of one year. The coefficient of heterotrophic activity, alkaline phosphatase activity and biological oxygen demand are used as an index of biological activity. The bacterial community was at maximum during spring, coinciding with high values of biological activity. Highest biological activity was observed in the bottom waters. Dissolved organic carbon showed a significant positive correlation with most of the biological activity parameters. This suggests that biological activity, as measured by the coefficient of heterotrophic activity, was more closely related to the concentration of substrates than to population density of heterotrophic bacteria. 相似文献
85.
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
86.
Phytoplankton ecology of the Lake of Menteith,Scotland 总被引:1,自引:1,他引:0
The results discussed in this paper represent the first seasonal ecological study carried out on the phytoplankton of the Lake of Menteith. All measured nutrients reached maximum levels during the winter, with silicate showing particularly high concentrations (up to 85 µg at Si l–1). During the summer period phosphate, nitrate and silicate showed almost complete exhaustion in surface waters. The lake water was consistently alkaline, never falling below pH 7, while the alkalinity ranged from 20 to 24 mg CaCO3 l–1. Generally, the nutrient status of the main inflow had a rapid effect on the water quality of the lake.The region of the lake under investigation showed no thermal stratification at any period of the year, although continuous thermal gradients were recorded in the winter. The continual circulation of the water mass probably prevented oxygen saturation from falling below 77% even following a large phytoplankton bloom and subsequent decomposition.From an examination of net phytoplankton samples the Lake of Menteith could be described as blue-green or blue-green/diatom in nature. From the quantitative study, large pulses of Melosira, Asterionella and Fragilaria were recorded in the spring. The disappearance of the species appears to be related to silicate limitation. The summer growth of Asterionella may have been promoted by a nitrogen source other than nitrate and nitrite, both of which were reduced to critical levels. This alternative source of combined nitrogen may have been contributed by nitrogen-fixing algae in the lake. Three species of Anabaena were recorded, all of which produced large populations during the year.Department of Botany, The University of GlasgowPresent Address: Department of Biology, College of Science, University of Sulaimaniyah, Sulaimaniyah, Iraq 相似文献
87.
Every two months, diel depth profiles were made of dissolved oxygen, pH, temperature and conductivity at two stations in Lake Kissimmee, Florida, from July 1974 through June 1975. Results suggest that stratification does not occur in the large (137 km2), shallow (mean depth 2.5 m) lake, though steep vertical gradients in these parameters may develop. The data also suggest that when these gradients do occur, they rapidly degenerate at night or under slight wind stress. Since many Florida lakes are relatively shallow (mean depth < 5 m) and topography offers little obstruction to wind action, it is believed that the holomictic condition observed in Lake Kissimmee may be typical of the state's lakes, particularly those in the central portion of the peninsula. 相似文献
88.
Phytoplankton productivity was measured in Byram Lake Reservoir during summer 1977. Depth integrated productivity (0–5 gC m– 2 d–1) increased with station depth, which together with visibility measurements indicated that light did not limit deep station productivity (C1 and S2). Macrophytes at station C5 (shallow) reduced the euphotic zone to 0 in June.On a unit depth basis, C5 was the most productive station. Apparently changes in macrophyte growth, regulated by light and temperature, controlled phytoplankton production. At C1, productivity was related to levels of different nutrients at different depths, the thermocline influencing nutrient availability at mid-depth. At S2, NH3-N controlled mid-depth productivity. Surface and mid-depth productivity appeared influenced by factors not measured in this study. 相似文献
89.
J. Devaux 《Hydrobiologia》1980,68(1):17-34
At 1197 m in the French Massif Central, lake Pavin has a volcanic origin. It is a meromictic lake of 44 ha area and 98 meters depth.Zooplancton samples (250 liters) were collected bimonthly with a water pump from May 1973 to April 1974 at six depths from surface to 20 meters.Countings were made to study the dynamics of two Cladocera: (Daphnia longispina and Ceriodaphnia quadrangula), two copepode populations, the calanoide Acanthodiaptomus denticornis and the cyclopoide Cyclops abyssorum. For the last two species, males, females, ovigerous females, Nauplius larvae and each of the five copepodite stages were differentiated.If Cladocera have a period of development limited from June to September for Ceriodaphnia and from June to December for Daphnia, copepods are presents all around the year with two principals periods of reproduction. The first during spring (March–April), the second during fall (October–November). If this second generation presents an important development for Cyclops abyssorum, that is not the same for Acanthodiaptomus denticornis, in which species nauplius larvae died in winter. The synthetical mathematical model realized by Principal Components Analysis illustrates the relationships between phyto-and zooplancton and bio-physico-chemicals parameters and specially the fact that, in this lake, the highest values of phytoplanctonic primary production and activity coefficient (Production/Standing crop) are found when herbivorous zooplancton presents the more important development and nutrients their lowest concentrations. 相似文献
90.
Synopsis Ages determined by counts of apparent annuli on scales, sagittae, vertebrae, pectoral fin ray and dorsal fin spine cross sections
of largemouth bass from northern populations, which are older and slower growing fish than in the southern parts of its native
range, were compared to establish the accuracy of each method. Linear regression techniques indicated strong agreement (r>
0.9) among ages assigned from the examination of scales, sagittae, and vertebrae. The pattern of growth zones on pectoral
fin ray and dorsal fm spine cross sections proved too variable for accurate age determination. Limited data suggest that ages
greater than 7+ assigned from scales were more likely to underestimate true ages than the other body parts used, although
none of these methods gave satisfactory results. Examination of scales from recovered tagged fish, and the similarity between
back-calculated lengths of fish through age 7+ to annulus I and observed lengths of juvenile largemouth bass near the end
of their first growing season, support the validity of ages determined from scales.
Despite a very limited amount of habitat suitable for largemouth bass and severe climatic conditions, growth of this species
in Tadenac Lake was similar to growth in other waters north of the Great Lakes. Differences in physical characteristics among
these waters does not appear to influence growth rates of largemouth bass, but probably affects production and biomass. 相似文献