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  • 1
    Electronic Resource
    Electronic Resource
    The spring development of phytoplankton in Lake Erken (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 7 (1977), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. In Lake Erken there is a regular phytoplankton peak at ice-breakup in the spring. Pechlaner (1970) studied the spring outburst of 1960. We carried out a similar study in 1973, when the climatic factors were completely different, with only 10 cm of ice and almost no snow. Thus, due to light penetration, there was a high phytoplankton biomass under the ice as early as March. Stephanodiscus astraea (Ehr.) Grun. and Asterionella formosa Hass. dominated the biomass during the spring development in 1973 instead of the normally dominating S. hantzschii v. pusillus Grun.The nutrient decrease was slower in 1973 than in 1960. A comparison of carbon assimilation and the decrease of nitrate and phosphate indicate sufficient nutrient supply in 1973. In 1960, the population grew logarithmically until the nutrients became limiting. In 1973, the average biomass was greater, but the mean probable primary production was only half that of 1960. From the activity coefficients for the 2 years it is also clear that, in 1960, S. hantzschii v. pusillus was highly productive during its short but intensive growth period. Its minute size and high surface/volume ratio enabled it to take up nutrients rapidly and efficiently. The chlorophyll content of S. astraea in 1973 was only half as much as that of S. hantzschii v. pusillus in 1960. Since the light conditions under the ice in March 1973 were more unfavourable than during the exponential phase of 1960, production was much lower.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1977.tb01680.x
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  • 2
    Electronic Resource
    Electronic Resource
    Seasonal dynamics of a cyanobacteria-dominated microbial community in surface sediments of a shallow, eutrophic lake (1989)
    Springer
    Aquatic sciences 51 (1989), S. 153-178 
    Details
    ISSN: 1420-9055
    Keywords: sediments ; cyanobacteria ; Microcystis ; bacterial biomass ; bacterial production ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seasonal variation of microbial biomass and activity in the surface sediments (0–10 cm) of the shallow, eutrophic Lake Vallentunasjön was followed during one year. “Overwintering”Microcystis colonies dominated the microbial community during all seasons, constituting 60–90% of the total microbial biomass. Expressed on an areal basis, the benthic biomass was, throughout the year, larger than or similar to the planktonic biomass during the peak of the summer bloom, indicating an ability of the colonies to survive in the sediments for extended periods. Abundance of “other”, non-photosynthetic bacteria varied in the range 3.0–15.5 · 1010 cells g−1 d. w. over the year with minimum values in summer and maximum values in autumn in connection with the sedimentation of theMicrocystis bloom. A substantial part of the non-photosynthetic bacteria, up to circa 40%, was associated with the mucilage of healthyMicrocystis colonies. Bacterial production (3H-thymidine incorporation) appeared to be strongly temperature dependent and less influenced by the seasonal sedimentation pattern. Our data indicate an increasing proportion of non-growing cells in autumn and winter. Biomass-bound phosphorus constituted a significant portion, circa 10%, of the phosphorus content in Lake Vallentunasjön sediments. This pool has normally been overlooked in studies on phosphorus dynamics in lake sediments. Different mechanisms whereby organic phosphorus can be released from the sediments are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879300
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  • 3
    Electronic Resource
    Electronic Resource
    Phosphorus in sediments — speciation and analysis (1988)
    Springer
    Hydrobiologia 170 (1988), S. 91-101 
    Details
    ISSN: 1573-5117
    Keywords: phosphorus ; sediments ; fractionation ; forms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Characterization of sediment phosphorus is commonly based on sequential chemical extractions, in which phosphorus is supposed to be selectively removed from different compounds in the sediments. The first extraction schemes were designed to quantify discrete chemical or mineralogical compounds. As extraction schemes have been tested on different sediments, several systematic errors have been detected and the schemes have been modified and simplified accordingly. Other chemical extractions or treatments have attempted to determine phosphorus bound to particles with a certain strength or binding energy, the purpose being to determine the labile, loosely bound, exchangeable, mobile or algal-available fraction of sediment phosphorus. All extraction procedures yield operationally defined fractions and cannot be used for identification of discrete phosphorus compounds. The many methodological modifications make it necessary to be cautious when comparing results from the literature in this field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024900
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  • 4
    Electronic Resource
    Electronic Resource
    Bioavailability of different phosphorus forms in freshwater systems (1988)
    Springer
    Hydrobiologia 170 (1988), S. 133-155 
    Details
    ISSN: 1573-5117
    Keywords: bioavailability ; phosphorus ; dissolved ; particulate ; bioassay ; 32P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The recent literature on the bioavailability of different forms of P in freshwater systems is reviewed. Bioavailable P is defined as the sum of immediately available P and the P that can be transformed into an available form by naturally occurring processes. Methods used to estimate the bioavailable P pool, which vary between studies largely depending on the time perspective applied, are critically evaluated. Most studies on particulate P aim to determine the potentially available P pool. Potential bioavailability of particulate P is normally analysed in bioassays with algal yield determinations and the available P fraction is characterized from interpretations of results of sequential chemical extractions. NaOH-extractable P is in most studies the most algal-available P fraction. For soil samples and tributary water particulate matter, NaOH-P has often been found to be equal to algal extractable P. In other studies depletions of NaOH-P have accounted for the algal P uptake, but only a minor proportion of the fraction has been utilized. Organic P in lake water particulate matter and bed sediments of eutrophic lakes can also be algal-available to a significant extent. Studies on the bioavailability of dissolved P have often been concerned with immediate availability, or the minimum amount of available P. Such studies need other types of experimental design and normally assays with radiotracers are used. Immediately available P is frequently found to be less than P chemically assessed as dissolved reactive P (DRP) at low (〈 10 µg DRP·l-1) concentrations. However, immediate availability may also approach or exceed DRP concentrations, especially at higher concentrations. Potential bioavailability, assayed as for particulate P, may generally render higher bioavailability than P assayed as immediately available. Large fractions of dissolved P remain unutilized and are primarily found in the high molecular weight fraction of dissolved P.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024902
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  • 5
    Electronic Resource
    Electronic Resource
    Exchange of phosphorus across the sediment-water interface (1988)
    Springer
    Hydrobiologia 170 (1988), S. 229-244 
    Details
    ISSN: 1573-5117
    Keywords: phosphorus ; sediments ; retention ; release ; microbial processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this article, principles of phosphorus retention and phosphorus release at the sediment-water interface in lakes are reviewed. New results and hypotheses are discussed in relation to older models of phosphorus exchange between sediments and water. The fractional composition of sedimentary phosphorus is discussed as a tool for interpretation of different retention mechanisms. Special emphasis is given to the impact of biological, particularly microbial, processes on phosphorus exchange across the sediment-water interface and to the significance of biologically induced CaCO3 precipitation to phosphorus retention in calcareous lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024907
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  • 6
    Electronic Resource
    Electronic Resource
    Coupling between benthic biomass of Microcystis and phosphorus release from the sediments of a highly eutrophic lake (1992)
    Springer
    Hydrobiologia 235-236 (1992), S. 375-385 
    Details
    ISSN: 1573-5117
    Keywords: Microcystis ; microbial activity ; sediment ; phosphorus ; internal loading
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variations in microbial biomass and activity in the sediments of hypereutrophic Lake Vallentunasjön were followed during a period of 5 years. The data were compared to the calculated release of phosphorus from the sediments during the same period. A strong co-variation was found between biomass of Microcystis, heterotrophic bacterial activity in the sediments and internal phosphorus loading. These parameters exhibited mainly a declining trend during the investigation period. A pronounced stability of the sediment chemistry, including the fractional composition of the sediment phosphorus, during the studied period indicates that microbial activity affected the phosphorus release from the sediments. Calculations of the percentage of sediment bacteria that was associated to the mucilage of Microcystis colonies imply, together with the specific bacterial production, that Microcystis in the sediment stimulates bacterial production. In the highly phosphorus-saturated sediments of Lake Vallentunasjön this would ultimately lead to an increased release of phosphorus from the sediment. Lake Vallentunasjön does not follow the common pattern of recovery after reduction of external phosphorus loading. The large biomasses and long survival of Microcystis in the sediment are probably important reasons for the delayed recovery of the lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00026227
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  • 7
    Electronic Resource
    Electronic Resource
    Different patterns of phosphorus release from lake sediments in laboratory experiments (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 415-429 
    Details
    ISSN: 1573-5117
    Keywords: phosphorus release ; sediment ; nitrate ; redox-potential ; sorption ; fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phosphorus release from surface sediments of eight lakes, mainly shallow lakes in agricultural areas, was studied in laboratory batch experiments with additions of acetate and/ or nitrate. The lake sediments could be separated into three categories. Some sediments did not release phosphorus under any conditions. The second category showed a high phosphorus release rate when acetate was added, in order to stimulate bacterial activity and oxygen consumption. The addition of nitrate, only, stabilized the redox conditions and prevented phosphorus release. This pattern followed the classical theories of Einsele and Mortimer. The third sediment category released phosphorus up to some level which remained constant throughout the experiment, and was independent of acetate and/or nitrate additions. Several extraction procedures and adsorption-desorption experiments were performed in order to characterize the sediment phosphorus and thus explain the different behaviours of the three sediment categories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02391957
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  • 8
    Electronic Resource
    Electronic Resource
    Different patterns of phosphorus release from lake sediments in laboratory experiments (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 415-429 
    Details
    ISSN: 1573-5117
    Keywords: phosphorus release ; sediment ; nitrate ; redox-potential ; sorption ; fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phosphorus release from surface sediments of eight lakes, mainly shallow lakes in agricultural areas, was studied in laboratory batch experiments with additions of acetate and/ or nitrate. The lake sediments could be separated into three categories. Some sediments did not release phosphorus under any conditions. The second category showed a high phosphorus release rate when acetate was added, in order to stimulate bacterial activity and oxygen consumption. The addition of nitrate, only, stabilized the redox conditions and prevented phosphorus release. This pattern followed the classical theories of Einsele and Mortimer. The third sediment category released phosphorus up to some level which remained constant throughout the experiment, and was independent of acetate and/or nitrate additions. Several extraction procedures and adsorption-desorption experiments were performed in order to characterize the sediment phosphorus and thus explain the different behaviours of the three sediment categories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00000041
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  • 9
    Electronic Resource
    Electronic Resource
    Different patterns of phosphorus release from lake sediments in laboratory experiments (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 415-429 
    Details
    ISSN: 1573-5117
    Keywords: phosphorus release ; sediment ; nitrate ; redox-potential ; sorption ; fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phosphorus release from surface sediments of eight lakes, mainly shallow lakes in agricultural areas, was studied in laboratory batch experiments with additions of acetate and/ or nitrate. The lake sediments could be separated into three categories. Some sediments did not release phosphorus under any conditions. The second category showed a high phosphorus release rate when acetate was added, in order to stimulate bacterial activity and oxygen consumption. The addition of nitrate, only, stabilized the redox conditions and prevented phosphorus release. This pattern followed the classical theories of Einsele and Mortimer. The third sediment category released phosphorus up to some level which remained constant throughout the experiment, and was independent of acetate and/or nitrate additions. Several extraction procedures and adsorption-desorption experiments were performed in order to characterize the sediment phosphorus and thus explain the different behaviours of the three sediment categories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00940131
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  • 10
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    Factors Controlling the Seasonal Variation of Nitrate in Lake Erken (1981)
    Wiley
    Details
    Publication Date: 1981-01-01
    Print ISSN: 1434-2944
    Electronic ISSN: 1522-2632
    Topics: Biology
    Published by Wiley
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