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  • 1
    Electronic Resource
    Electronic Resource
    Divergent members of the bacterial division Verrucomicrobiales in a temperate freshwater lake (1998)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 25 (1998), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Bacterial diversity in the water column of a freshwater lake in the Netherlands was investigated by analysis of 16S rRNA gene sequences recovered through PCR amplification from total community DNA. Among 23 unique cloned sequences, two appeared to belong to the recently described bacterial division Verrucomicrobiales. One of the two sequences was most similar to a group of environmental clones that form a distinct lineage within the division. The other sequence was divergent (less than 85% similarity) from all 16S rRNA gene sequences, both from cultivated species and from environmental clones, known in this division to date. Analysis by denaturing gradient gel electrophoresis (DGGE) and sequencing of DNA recovered through excision from the DGGE gel showed that the two sequence types were present in the lake throughout the year.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.1998.tb00469.x
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  • 2
    Electronic Resource
    Electronic Resource
    Energy requirements for growth and maintenance of Scenedesmus protuberans Fritsch in light-limited continuous cultures (1980)
    Springer
    Archives of microbiology 125 (1980), S. 9-17 
    Details
    ISSN: 1432-072X
    Keywords: Scenedesmus protuberans Fritsch ; Continuous culture ; Light limitation ; Temperature effect ; Irradiance effect ; Growth efficiency ; Maintenance energy ; Green algae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Scenedesmus protuberans Fritsch was grown in light-limited continuous cultures with a light-dark cycle, at temperatures of 20° and 28° C. At 20° irradiances of 12 and 38 W m−2 were used, at 28° 38 W m−2. The relationships between growth rate and light uptake rate were of diphasic linear character. With the lower growth rates the relationships were defined with the parameters μ e , i.e. the specific maintenance rate constant, and c, the “true” efficiency of light energy conversion into biomass. The μ e -value was dependent on temperature, the c on irradiance. In cultures, incubated in prolonged darkness, decrease rates of biomass were comparable to the derived μ e -values. Both diphasic linear relationships between growth rate and light uptake rate and the same order of magnitude of μ e -values could be derived from literature data on other green algae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403192
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of wind on a shallow lake ecosystem: Resuspension of particles in the Loosdrecht Lakes (1986)
    Springer
    Aquatic ecology 20 (1986), S. 109-120 
    Details
    ISSN: 1573-5125
    Keywords: seston ; epipelon ; sediment ; wind effects ; resuspension ; horizontal transportation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Horizontal variation of seston concentration in the shallow, eutrophic Loosdrecht Lakes (A=9.8 km2; $$\overline z $$ =1.9 m) was studied in relation to windspeed and effective fetch. Simple wave theory was applied in order to predict resuspension using wind data from a nearby meteorological station. Most results were consistent with the theory, but a clear limit for the occurrence of resuspension could not be established. Generally, changes in epipelon—the particles at the sediment-water interface — were not directly related to computed frequency of resuspension at the sampling station. The frequency was estimated for 37 grid points over the entire lake. Resuspension was computed to affect high percentages of the lake area in winter. In summer the frequency was much lower, but in June and July 1984 there were days with nearly 50% of the lake area subject to resuspension. The resulting input of particulate organic carbon into the water column during these days was estimated to equal 12–25 times the daytime phytoplankton carbon fixation. Most of the resuspended matter appeared to be redeposited rapidly. The computed frequency of resuspension for the 37 locations of the lake varied between 7 and 48 days in 1984.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02291156
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  • 4
    Electronic Resource
    Electronic Resource
    Periphyton in Lake Vechten, with emphasis on biomass and production of epiphytic algae (1979)
    Springer
    Aquatic ecology 13 (1979), S. 116-116 
    Details
    ISSN: 1573-5125
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Characteristics of the periphyton associated with the submerged macrophytesCeratophyllum, Elodea andMyriophyllum were similar. During the whole growing season the periphyton dry weight often exceeded that of the macrophyte. The periphyton contained much detritus and carbonates, and the epiphytic algae were accompanied by large numbers of bacteria, protozoans and rotifers. Attached algae were scarce, but motile diatoms were abundant throughout the year. Thus the periphyton showed the features of a benthic community. Consequently, the role of the macrophytes would be rather the extension of the bottom area instead of actively promoting the growth of microorganisms by providing minerals or excreting organic substances. During the peak of the littoral development the epiphytic algae expressed a high photosynthetic capacity, while at the same time the periphyton dark respiration was intense. After measurements of the depth distribution of biomass and light in aCeratophyllum stand, it was concluded that the contribution of the epiphytic algae to the production in the lake's littoral zone was substantial. Furthermore, on a daily basis, the total association of macrophytes and periphyton would be oxygen consuming due to heterotrophic activity, notably mineralization of the detritus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02284744
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  • 5
    Electronic Resource
    Electronic Resource
    The eutrophic Loosdrecht Lakes: Current ecological research and restoration perspectives (1986)
    Springer
    Aquatic ecology 20 (1986), S. 61-75 
    Details
    ISSN: 1573-5125
    Keywords: eutrophication ; lake restoration ; blue-green algae ; zooplankton ; seston ; epipelon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Features of the Loodsrecht Lakes, with emphasis on the main lake, are discussed with reference to restoration. Characteristics of the present situation are: (1) very low water transparency-Secchi-disc readings around 0.3 m occur in all seasons; (2) relatively small seasonal changes in sestonic matter; (3) important input of resuspended particles into the seston; (4) predominance of filamentous blue-green algae for most of the year; (5) relative scarcity of crustacean zooplankton, while rotifers are abundant; (6) poor development of littoral communities, and absence of benthic producers. The blue-green algae maintain high population density at very low growth rates: rates of loss are low. The zooplankton grazing rate is low due to inefficient filtering, but predation of larger crustaceans by fish may also be important. Studies on epipelon indicated that loss by deposition may be largely compensated by resuspension. Starting in 1984, the external phosphorus loading was markedly reduced. Results for 1984 and 1985 indicate that complementary measures are needed in order to improve water quality. Action should be directed towards increasing the phytoplankton turnover rates. Accelerated specific growth rate can be expected to accompany lower biomass, more successful competition by other algal groups, and enhancement of grazing pressure. Considering the shallowness of the system, promotion of littoral development and return of submerged vegetation may be important in establishing a new equilibrium of the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02291151
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  • 6
    Electronic Resource
    Electronic Resource
    Phosphate uptake capacity of summer phytoplankton of the Loosdrecht Lakes in relation to phosphorus loading and irradiance (1986)
    Springer
    Aquatic ecology 20 (1986), S. 101-107 
    Details
    ISSN: 1573-5125
    Keywords: phytoplankton ; laboratory scale enclosure ; phosphorus loading ; phosphate uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Summer populations of the phytoplankton of the Loosdrecht Lakes were enclosed in laboratory scale enclosures (LSE), supplied with 7.5 μg P.l−1.d−1 and 105 μg P.l−1.d−1, respectively. The maximum initial phosphate uptake rate (Vm) was related to irradiance and primary production. At phosphate uptake saturating light-irradiance Vm values up to 4 times the Vm values in the dark were measured. The phosphate uptake capacity per unit dry weight remained more or less constant throughout the experiments in the LSE receiving the lower amount of phosphorus, and declined in the LSE receiving the higher amount of phosphorus. Within the range of Vm values measured (〈10 μg P.mg DW−1.h−1 or 1,3 μg P. μg chla −1.h−1), the growth rate of the phytoplankton was not influenced by alterations in phosphorus availability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02291155
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  • 7
    Electronic Resource
    Electronic Resource
    Subsurface irradiance reflectance spectra of inland waters differing in morphometry and hydrology (1997)
    Springer
    Aquatic ecology 31 (1997), S. 313-323 
    Details
    ISSN: 1573-5125
    Keywords: optical properties ; remote sensing ; spectral database ; water quality monitoring ; water typology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A database has been established for relating subsurface irradiance reflectance, i.e. water ‘colour’, to the optical properties and water quality parameters of more than 120 Dutch inland water bodies. The concentrations of total chlorophyll-a (TChl-a = chlorophyll-a plus phaeopigment), total suspended matter and the Secchi-disc depth varied between 0.6 and 468 mg m-3, 0.8 and 98 g m-3, and 0.15 and 5.50 m, respectively. The water bodies represented very different water types based on morphometry and hydrology. The depth ranged from 0.4 to 40 m, and the surface area from 0.25 ha (fens in the moorland Peel) to 1200 km2 (Lake IJsselmeer). The mean specific phytoplankton absorption coefficient at 676 nm was 0.013 ± 0.003 m2 (mg TChl-a)-1. The absorption by tripton and dissolved humic substances at 440 nm varied between 0.1 and 16.4 m-1, and 0.1 and 65.5 m-1, respectively. By using the spectral position and magnitude of the subsurface irradiance reflectance peak alone, it was possible to distinguish groups of water bodies according to a classical typology based on morphometry and hydrology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009916501492
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  • 8
    Electronic Resource
    Electronic Resource
    A comparison of primary production measurements using two laboratory systems with differences in light quality (1986)
    Springer
    Aquatic ecology 20 (1986), S. 93-99 
    Details
    ISSN: 1573-5125
    Keywords: primary production ; oxygen technique ; light quality ; incubator ; laboratory scale enclosure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Primary production measurements were carried out simultaneously, using two laboratory systems with different light conditions: (1) a'classical' incubator and (2) a Laboratory Scale Enclosure. The model used for calculating primary production (STEELE, 1965) does not correct for spectral changes caused by high phytoplankton biomass. In the incubator, light of almost all wavelengths decreased more or less according to the attenuation of total PhAR in water. In the LSE, high absorption was found of the blue light and some of the red light, which was due to the high sestonic concentration. The Steele function provided a good fit for both sets of data. The depth integrated gross production values derived from the simultaneous measurements were not significantly different.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02291154
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of a light-dark cycle on the growth ofScenedesmus protuberans Fritsch in light-limited continuous cultures (1975)
    Springer
    Aquatic ecology 9 (1975), S. 71-80 
    Details
    ISSN: 1573-5125
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Growth ofScenedesmus protuberans Fritsch was studied in light-limited chemostat type continuous cultures, with a light-dark cycle of 16, respectively 8 hours. In these cultures a synchronization of groups was found, which phenomenon is discussed. Analysis of chlorophyll content of the biomass showed that the synthesis of chlorophyll is influenced strongly by reproductive processes. No such influence was found for the total phosphorus content, which also remained the same in the light and in the dark period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257639
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  • 10
    Electronic Resource
    Electronic Resource
    Optical teledetection of the vertical attenuation coefficient for downward quantum irradiance of photosynthetically available radiation in turbid inland waters (1997)
    Springer
    Aquatic ecology 31 (1997), S. 299-311 
    Details
    ISSN: 1573-5125
    Keywords: irradiance reflectance ; large rivers ; phytoplankton production ; remote sensing ; shallow lakes ; underwater light
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Depth profiles of downward quantum irradiance of photosynthetically available radiation in situ and spectral subsurface irradiance reflectance, obtained from water-leaving radiance, were determined in different inland water types. These included the large, shallow and eutrophic IJssel lagoon in the Netherlands, eighteen Dutch lakes differing in depth and trophic state, and the large, shallow and eutrophic Lake Tai in China. The attenuation coefficient for downward irradiance ranged from 0.7 to 5.4 m-1. An empirical relationship with the backscattering coefficient in the near-infrared waveband, derived from the reflectance, and three spectral reflectance band ratios explained 91% of the variation. The potential assessment of the spatial distribution of phytoplankton production through shipboard optical teledetection of the concentration of chlorophyll-a and the attenuation coefficient for downward irradiance is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009902627476
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