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  • 11
    ISSN: 1573-5117
    Keywords: shallow lake ; sediment ; dy ; phosphorus ; calcium ; metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A chemical characterization of the surficial sediment (0–20 cm) of type `dy' (org-Cpart/TNpart〉10) of the anthropogenically polluted shallow Lake Petersdorf is presented. Eighty samples were analyzed for a set of parameters, i.e. dry weight, loss on ignition (LOI), total inorganic carbon (TIC), N, S, P, Ca, Si, As, Fe, Al, Mn, Zn, Cd, and Pb. LOI, TIC, N, S, Ca, P, and Zn tend to accumulate at a water depth 〉2 m (70.6% of the lake surface) in contrast to Mn and Fe which are more widely distributed, and Cd and Pb which are accumulated in the lake part close to a road. The enrichment factors of certain elements, e.g. Al (23.9%), Si (31.5%), P (12.2%), and Ca (68.7%) from 20 cm sediment depth up to the surface, are attributed to incisive changes in the immediate catchment. Erosion, fertilization, amelioration, and separation of the peatland north of the lake by a dam within the last 60 yrs resulted in the change of Lake Petersdorf from a dystrophic to a eutrophic stage. This enhanced the mineralization of its meso-humic (LOI/TNpart=20.6) sediment.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 1573-5117
    Keywords: geogenic acidic lakes ; pH ; food web ; phytoplankton ; zooplankton ; corixids ; seasonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acidic mining lakes (ML) in Lusatia (Germany) are characterised by their geogenically determined chemistry. The present study describes the structure, main components and relationships within the food webs of three acidic mining lakes with different pH values (ML 111: pH 2.6; ML 117: pH 2.8; ML Felix: pH 3.6) in order to show their typical characteristics. The investigation covered the period 1995–1997. The number of species and the biomass are both low, but increase with increasing pH. Planktonic components in the most acidic ML 111 (pH 2.6–2.9) comprise bacteria, Ochromonas spp. and Chlamydomonas spp. and a few rotifers (E. worallii, C. hoodi). Heliozoans are the top-predators. In ML 117 (pH 2.8–3) Gymnodinium sp., ciliates, the rotifer B. sericus and the pioneer crustacean Chydorus sphaericus join the pelagial community. Heliozoans were not found in ML 117 or ML Felix (pH 3.4–3.8). ML Felix had the most taxa. The benthic food chain of all three lakes includes phytobenthic algae as producers, chironomids as primary consumers and corixids as top predators in the profundal. Corixids predate on small cladocerans inhabiting the pelagial in lakes with a pH above 2.8 such as ML Felix. They invade the pelagial and act as a connecting link between the benthic and the pelagic food chains, which are isolated in lakes with a lower pH. Occasionally primary producers and consumers were abundant in all three lakes. These organisms do not depend on the degree of acidity, but on the availability of essential ressources. Mass variations covered up any seasonal variation in the extremely acidic ML 111 (0.9 mm3 l−1), while in the other two lakes seasonal patterns of biomass were found.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 275-276 (1994), S. 173-186 
    ISSN: 1573-5117
    Keywords: polymixis ; phytoplankton growth ; cyanophyta ; diatoms ; nutrient stress ; mixing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The polymictic properties of Lake Müggelsee, a eutrophic shallow lake in Berlin, are described by the water column stability (N 2) and gradients in saturation of oxygen at the deepest site of the lake (7.5 m). Mixing and stratification changed irregularly up to 7 times during the vegetation season (April to September), as was indicated by all of the stratification parameters. Thermally stable conditions generally lasted 1–2 weeks. A maximum of 5 weeks stratification was observed in 1982. In order to investigate the response of algal development, the internal rates of change of the dominant algal species in the lake during the vegetation period were estimated from weekly measurements of phytoplankton biomass from 1980 to 1990. The necessity taking a mixed sample in a shallow lake is discussed. The polymictic properties favoured the development of specific blue-green algal species; there dominance was also favoured by the trophic conditions. Among the dominant blue-greens the growth of Limnothrix redekei was independent of polymixis whereas stratification supported the starting conditions for the summer blue-greens Aphanizomenon flos-aquae and Planktothrix agardhii. After these algae reached a distinct level of biomass, they grew under mixing as well as under stratified conditions. For the development of solitary centric diatoms during summer regulation by growth restriction through nutrient limitation, esp. dissolved silicon was more important. However, Melosira sp. developed well under stratified conditions but collapsed due to increased sinking losses when the water column became too stable. An attempt is made to apply Reynolds' possibility matrix of the most likely phytoplankton assemblages as a function of nutrients and mixing in the shallow Lake Müggelsee.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 275-276 (1994), S. 187-195 
    ISSN: 1573-5117
    Keywords: phytoplankton growth ; nutrient load ; dilution ; competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influences of imports of nutrients and planktonic algae from the River Spree on the dynamics of phytoplankton were examined in the shallow, eutrophic Müggelsee, which has a retention time of only 42 days. Phytoplankton biomass and nutrient concentrations were measured in both the lake and its inflow from 1980–1990. On a long-term average, mean biomass as well as vitality of most dominant phytoplankton populations in the lake were not significantly different from those in the river. Nevertheless, during distinct periods the external rates of biomass change of single lake populations (due to dilution or enrichment) were as high as the lake internal ones. The import of inocula populations from the river probably induced the formation of the typical community structure in the lake. Growth and decay of phytoplankton populations in the river strongly influenced the load of dissolved nutrients and thus indirectly the dynamics of planktonic algae in the downstream lake. For example, intensive assimilation of phosphorus by riverine algae in spring intensified the P-shortage and supported possible P-limitation of algal growth in the lake at that time. In years with high vernal biomass of centric diatoms in the river, and thus diminished import of dissolved silicon, the growth of diatoms was suppressed and that of cyanobacteria was favoured in the lake during summer.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 29 (1999), S. 98-109 
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Seen mit Wasser, so sauer wie verdünnte Essigsäure, so sauer wie manche Kraterseen, gibt es solche Seen in Deutschland? Ja, sie gibt es, und zwar sogar recht zahlreich in den alten und vor allem in den neuen Bundesländern. Alle diese Seen sind künstlicher Natur und treten im Zusammenhang mit dem Abbau von Bodenschätzen auf. Durch diesen Vorgang werden tiefere Schichten des Deckgebirges belüftet und mit Wasser versorgt, so daß eine chemische und vor allem mikrobiologische Oxidation von reduzierten Schwefelkver bindungen (Sulfiden) einsetzen kann. Dieselben Vorgänge laufe auch auf und in den Abraumhalden ab. Sulfide sind sehr häufige Begleiter von Braun- oder Steinkohlevorkommen. Ein wesentlicher Teil der Wasserkontaminationen im mitteldeutschen und Lausitzer Raum ist in der Tat mit der Braunkohleförderung verbunden. Ferner sind die meisten, abbauwürdigen Metallvorkommen ebenfalls in sulfidischen Erzen zu finden, so daß deren Abbau zu denselben Oxidation führt, die international als Als Mine Drainage bezeichnet werden.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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