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  • 1
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Pty
    Lakes & reservoirs 5 (2000), S. 0 
    ISSN: 1440-1770
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography
    Notes: External and internal phosphorus loading was studied in 1996 in the anthropogenically eutrophicated Lake Jabel, which is located in Mecklenburg (north-eastern Germany). It has a dimictic 23-m-deep northern basin, a 19-m-deep middle basin and a 6-m-deep polymictic southern basin. The main tributary, Grabowhöfer Grenzgraben, which enters via a leaching field from a waste-water treatment plant, has been identified as the major nutrient discharge (80% of total phosphorus loading) into the northern basin. The sediment is the second largest source of phosphorus for Lake Jabel, contributing 25.7%, 27.4% and 2.4% of the overall phosphorus load to the northern, middle and southern basins, respectively. Although the favoured diversion of the Grabowhöfer Grenzgraben would contribute to a reduction of 1.22 t P and 20.94 t NO3-–-N per year, it is mainly rejected for the following reasons. If the extreme monthly nitrate supply, between 4.84 and 189.6 mg N m-2 day–1 ceased, the release of redox-sensitive phosphorus in the northern basin would increase by a factor of 0.54, which is with 41.1% total phosphorus, twice as high as that in the middle basin. In addition, the nitrate supply can substantially lower the seasonal precipitation of stable iron sulphides, which would otherwise lower the concentration of redox-sensitive phosphorus, but cannot change the phosphorus retention in the long term. Because of internal phosphorus sources, the diversion of the Grabowhöfer Grenzgraben would result in no substantial changes in the level of trophy.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Asia Pty. Ltd.
    Lakes & reservoirs 6 (2001), S. 0 
    ISSN: 1440-1770
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography
    Notes: After the reduction in external phosphorus-load (P-load), in-lake measures became practicable for eutrophic Lake Jabel. The benthic release of phosphorus (P) was efficiently suppressed by a significant nitrate supply via its main tributary. The in-situ stimulation of P-release as a result of the temporary decrease in this nitrate load, and the simultaneous P-removal by deep-water siphoning and external P-elimination was primarily designed for the faster deprivation of P from lake sediment. This new strategy was aimed at exhausting the ‘P-surplus’, that is, the mobile redox-sensitive iron-bound P-portions of the uppermost sediment layers, where a re-supply from deeper layers is needed within the stratification period of 2 consecutive years of operation of the P-elimination system. By studying early benthic P-diagenesis it remains to be demonstrated whether this procedure can contribute to a re-availability of P-binding sites to guarantee the long-term effect of the measure.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-9893
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Type of Medium: Electronic Resource
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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 433 (2000), S. 123-128 
    ISSN: 1573-5117
    Keywords: phytoplankton ; acidic mining lakes ; autecology ; nanoflagellates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Most of the flooded, open-cast lignite mining lakes of Lusatia (Germany) impacted by the oxidation of iron sulphides (pyrite and marcasite) are extremely acidic. Of 32 lakes regularly studied from 1995 to 1998, 14 have a pH 〈3 (median pH 2.3–2.9). These lakes are typically buffered by high concentrations of Fe (III) and have high conductivity (1000–5000 μS cm−1). Concentrations of dissolved inorganic carbon (DIC) and phosphorus are typically extremely low. These factors result in a very different environment for algae than found in neutral and acid-rain impacted lakes. The planktonic algal flora is generally dominated by flagellates belonging to genera of Chlorophyta (Chlamydomonas), Heterokontophyta of the class Chrysophyceae (Ochromonas, Chromulina), Cryptophyta (Cyathomonas) and Euglenophyta (Lepocinclis, Euglena mutabilis). Near-spherical non-motile Chlorophyta (Nanochlorum sp.), Heterokontophyta of the class Bacillariophyceae (Eunotia exigua, Nitzschia), Dinophyta (Gymnodinium, Peridinium umbonatum), other Chlorophyta (Scourfieldia cordiformis) and Cryptophyta (Rhodomonas minuta) are also found.
    Type of Medium: Electronic Resource
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  • 6
    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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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 342-343 (1997), S. 269-284 
    ISSN: 1573-5117
    Keywords: shallow lakes ; eu-hypertroph ; Cyanobacteria ; morphometry ; mixing ; euphotic depth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There are different approaches for classifying deep andshallowwaters using physically and ecologically derived parameters.Nevertheless, transition states make it difficult to definebordercrossing points between the two types of limnetic ecosystemsand todistinguish more precisely between different types of shallow,especially highly eutrophicated lakes. We contribute adetailedanalysis of different characteristics of shallow waters fromlakesin the Berlin/Brandenburg-region. In the catchment area of theriver Dahme in Eastern Brandenburg (Scharmützelsee-region)wefind mainly shallow and highly eutrophicated lakes, dominatedbyCyanobacteria. ’Very shallow‘ lakes of different morphometry andtopography are compared with ’medium shallow‘ or deeper lakesinthe region with similar loading characteristics for thefollowingproperties: morphometry, topography, theoretical retentiontime,mixing intensity, nutrient dynamics, external and internalloading,underwater light climate, zeu/zmix,phytoplankton development and oxygen budget. We found that’veryshallow‘ lakes in the region are more efficient in convertingtheavailable phosphorus into phytoplankton biomass because of theconstant and sufficient underwater light climate due to thefavourable relation of zeu and zmix. Weconclude that the regular mixing regime guarantees a stableandnear optimum light/dark rhythm as well as higher heterotrophicactivities, stimulating primary production up to the upperlimit ofalgal development.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-5117
    Keywords: acidic mining lakes ; phytoplankton ; Chlamydomonas ; Ochromonas ; water chemistry ; limiting factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twenty-three extremely acidic (pH between 2.5 and 3.5) mining lakes in Lusatia (Germany) were analysed in order to classify their hydrochemistries and to assist the understanding of phytoplankton colonization of these extreme environments. Neither morphometric nor physical parameters influence phytoplankton composition but determine the extent to which the nutrient supply supports the mass development of Chrysophyceae and Chlorophyceae in certain layers of the water (hypo- or epilimnetic chlorophyll maxima and short mass developments). Conventional trophic classification is not readily applicable to these lakes but a chemical classification on the basis of hydrogen, total iron and acidity is proposed. Species of Ochromonas and Chlamydomonas dominate the phytoplankton in fourteen of the most acid lakes; dinoflagellates occurre additionally in four; a more diverse algal assemblage with diatoms and cryptophytes is found in lakes with moderately acidic (pH 5.7–7.0) or alkaline conditions (pH 7.0–9.4). The lake chemistry is the main determinant for the planktonic composition of the water bodies whereas the trophic state mainly determines the level of algal biomass.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-5117
    Keywords: phytoplankton succession ; chrysophytes ; winter ; ice-cover ; trophic gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phytoplankton succession in three shallow eutrophic and hypertrophic lakes located in the Scharmützelseeregion (East Brandenburg, Germany) is described for the extreme winter of 1995/96 before and during ice-cover. The lakes have been investigated since 1993 and pass along the tophic gradient from eutrophic, Petersdorfer See and Melangsee to hypertophic, Larger See. All lakes are dominated by cyanobacteria from early spring to late autumn. Due to low water temperature and low light intensity before ice-cover a decline of cyanobaterial biovolume initiated which led to the total disappearance of cyanobacteria in Melangsee for the whole ice-covered period, whereas their portion in Langer See with at least 6% (3 mm3 l-1) and in Petersdorfer See with 25% (5 mm3 l-1) of total biovolume was still considerable. The cyanobacterial breakdown was linked to a switch in dominance to flagellates which built up together with diatoms a subsequent peak of biovolume during ice-cover. Maximum phytoplankton biovolume under the ice peak reached 20 mm3 l-1 with chl-a concentrations up to 100 µg l-1. Oxygen saturation increased during ice-cover with a final oversaturation of more than 200% in the upper water column at the end of ice cover. These findings indicate that the winter period is also characterized by intensive photoautotrophic activities. Therefore, this period should be more worthy of note in investigations of phytoplankton succession and ecology.
    Type of Medium: Electronic Resource
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