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001-es BibID:BIBFORM032058
Első szerző:Korponai János (biológus)
Cím:Paleolimnological reconstruction of the trophic state in Lake Balaton (Hungary) using Cladocera remains / János Korponai, Katalin A. Varga, Timea Lengré, István Papp, Albert Tóth and Mihály Braun
Megjegyzések:The sediment of Lake Balaton (Hungary)provides important information about the lake's history,particularly with regard to eutrophication. In this study,we used fossil pigment analysis and subfossil Cladoceraremains preserved in a dated sediment core to identifytrophic stages from *250 BC to present. Dates of themost recent eutrophic events are in good agreementwithpreviously published data. In general, the abundanceand diversity of the Cladocera community increasedwith eutrophication and decreased with oligotrophication.The sediments of Lake Balaton were characterisedby Chydoridae remains, of which Alona species werethe most abundant. Of these, Alona quadrangularis andAlona affinis accounted for 40 and 20% of the totalCladocera remains, respectively. The trophic state ofLake Balaton varied between mesotrophic and eutrophicregimes. Seven different trophic periods wereidentified in Lake Balaton on the basis of SedimentaryPigment Degradation Unit (SPDU) content of thesediment. Eutrophic states were (1) from *250 to*30 BC, (3) between*300 and*590 AD, (5) between1834 and 1944 and (7) from the 1960s until present.Mesotrophic states were (2) *30 BC to *300 AD, (4)590?1834, (6) 1944?1960s.Discriminant analysis of thecladoceran data confirmed these historic events, exceptfor the short mesotrophic episode between 1944 and1960. The first stage of eutrophication of Lake Balaton(*250 to *30 BC) was characterised by extensivemacrophyte vegetation, as indicated by the increasingabundance of vegetation-associated Cladocera species(Eurycercus lamellatus, Sida crystallina, Pleuroxussp.). Intensification of eutrophication was identifiedsince the 1980s, reflected by a high abundance ofBosmina species. The most significant planktivorousfish of Lake Balaton was the Sabre carp (Pelecuscultratus), and when its number decreased, the abundanceof Bosmina species increased. This study showsthat Cladocera are responsive to trophic state changes,underlining their importance as a tool for the assessmentof lake eutrophication.[This study was financially supported byHungarian National Science Foundation, OTKA-T 049098 and Hungarian National Research and Development ProgramBALO? KO 3B022/04, TA? MOP 4.2.2-08/1-2008-0020, TA? MOP4.2.1/B-09/1/KONV-2010-0006.]
Tárgyszavak:Természettudományok Környezettudományok idegen nyelvű folyóiratközlemény külföldi lapban
Cladocera remains
Lake Balaton
Shallow lake
Megjelenés:Hydrobiologia. - 676 : 1 (2011), p. 237-248. -
További szerzők:Varga Katalin A. Lengré Timea Papp István (1980-) (vegyész) Tóth Albert (1966-) (biológus-ökológus) Braun Mihály (1966-) (vegyész, analitikus)
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001-es BibID:BIBFORM009591
Első szerző:Korponai János (biológus)
Cím:Transition from shallow lake to a wetland: a multi-proxy case study in Zalavári Pond, Lake Balaton, Hungary / János Korponai, Mihály Braun, Krisztina Buczkó, István Gyulai, László Forró, Judit Nédli, István Papp
ISSN:0018-8158 1573-5117
Megjegyzések:Lake Balaton, the largest shallow lake in Central Europe, has no natural outlet, therefore, underwent water level changes during its 15,000-17,000 years of history. The lake is very sensitive to both climate changes and human impacts. Surroundings have been inhabited since the Stone Age; however, heavy human impact can be recognized during the past 6000 years. In this study, we established three different stages for and reconstructed water level changes of Lake Balaton by geochemical data, subfossil Cladocera and diatom remains in the sediments of the Zalavári Pond, a part of the Kis-Balaton wetland. In 9900-8600 cal. year BP, climate was dry, water level was low, and there was a wetland in this area. Although organic matter content was low in the sediment, the ratio of Fe/Mn was high. Between 5600 and 5000 cal. year BP, water level increased, Fe/Mn ratio shows that oxygen conditions of sediments was improved in agreement with the relatively low number of diatom remains and dense chydorid remains. About 5000 cal. year BP, water level of Lake Balaton decreased as indicated by high organic content with low carbonate and high Fe/Mn ratio in the sediments (oxygen depletion). At the bottom of this section, high Fe and S concentrations showed accumulation of pyrite (FeS2) that is common in wetlands with very low redox potential. Low abundance of Cladocera remains together with rich and diverse diatom flora confirm the low water level hypothesis. Our data support that the water level of Lake Balaton was higher between 8600 and 5000 cal. year BP than it is at present.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Lake Balaton
cladocera remains
trace metals
shallow lake
Megjelenés:Hydrobiologia. - 641 : 1 (2010), p. 225-244. -
További szerzők:Braun Mihály (1966-) (vegyész, analitikus) Buczkó Krisztina (1962-) (biológus) Gyulai István (1980-) (biológus) Forró László (1954- ) (biológus) Nédli Judit (1980- ) (biológus) Papp István (1980-) (vegyész)
Internet cím:DOI
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001-es BibID:BIBFORM009590
Első szerző:Magyari Enikő (biológus)
Cím:Palaeolimnology of the last crater lake in the Eastern Carpathian Mountains: a multiproxy study of Holocene hydrological changes / Enikő Magyari, Krisztina Buczkó, Gusztáv Jakab, Mihály Braun, Zoltán Pál, Dávid Karátson, István Pap
Megjegyzések:A multi-proxy investigation (loss-on-ignition, major and trace elements, pollen, plant macrofossil and siliceous algae) was carried out on the sediment of a crater lake (Lake Saint Ana, 950 ma.s.l.) from the Eastern Carpathian Mountains. Diatom-based transfer functions were applied to estimate the lake's trophic status and pH, while reconstruction of the water-depth changes was based on the plant macrofossil and diatom records. The lowest Holocene water depths were found between 9000 and 7400 calibrated BP years, when the crater was occupied by Sphagnumbog. Significant increases in water depth were found from 5350(1), 3300(2) and 2700 cal yr BP. Of these, the first two coincided with major terrestrial vegetation changes, namely (1) the establishment of Carpinus betulus on the crater slope and (2) the replacement of the lakeshore Picea abies forest by Fagus sylvatica. The chemical record indicated significant soil changes along with the canopy changes (from coniferous to deciduous) that led to increased in-lake productivity and pH. A further increase in water depth around 2700 cal yr BP resulted in stable thermal stratification and hypolimnetic anoxia that via P-release further increased in-lake productivity and eventually led to phytoplankton blooms with large populations of Scenedesmus. High productivity was depressed by anthropogenic lakeshore forest clearances from ca. 1000 cal yr BP that led to the re-establishment of P. abies on the lakeshore and consequent acidification of the lake water. On the whole, these data suggest that Lake Saint Ana is a vulnerable ecosystem: in-lake productivity is higher under deciduous canopy and litter, and considerably repressed by coniferous canopy and litter. The lake today subsists in a managed environment that is far from its natural state. This would be a dense F. sylvatica forest supplying more nutrients and keeping up a more productive in-lake flora and fauna.
Tárgyszavak:Természettudományok Földtudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Hydrobiologia. - 631 (2009), p. 29-63. -
További szerzők:Buczkó Krisztina (1962-) (biológus) Jakab Gusztáv (1975- ) (paleontológus) Braun Mihály (1966-) (vegyész, analitikus) Pál Zoltán Karátson Dávid (1964- ) (földrajz-biológia tanár) Papp István (1980-) (vegyész)
Internet cím:DOI
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