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1.

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
Dátum:2011
ISSN:0018-8158
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
Bosmina
Cladocera remains
Chydoridae
Eutrophication
Fish
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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2.

001-es BibID:BIBFORM032057
Első szerző:Korponai János (biológus)
Cím:Cladocera response to Late Glacial to Early Holocene climate change in a South Carpathian mountain lake / János Korponai, Enikő Katalin Magyari, Krisztina Buczkó, Sanda Iepure, Tadeusz Namiotko, Dániel Czakó, Csilla Kövér and Mihály Braun
Dátum:2011
ISSN:0018-8158
Megjegyzések:This study explores changes in cladocerancomposition in a high mountain lake of the Retezat(Lake Brazi), the South Carpathian Mountains ofRomania, during the Late Glacial-Early Holocene(14,500-11,600 cal. yr. BP) transition using a paleolimnologicalapproach. The lake had a species poorcladoceran community throughout this period. Daphnialongispina, Chydorus sphaericus and Alona affiniswere the most common, showing marked fluctuations in their relative abundances through time. Distinctfaunal response to warming at the Younger Dryas(YD)/Preboreal transition was recorded by increasingfossil densities and distinct community compositionchange: Alona affinis became dominant while numbersof Chydorus sphaericus dramatically decreased.In the Early Holocene, the productivity of Lake Braziseem to have increased as reflected by higher numbersof Cladocera due to appearance of new species (Alonarectangula, A. quadrangularis and A. guttata) whichare common in productive waters. Significant negative correlation was found between average dorsal length of daphnid ephippia and the NGRIP d18O isotopevalues. Given the absence of fish predation, changes inDaphnia ephippia size were taken to indicate climaticchange: larger ephippium size inferred cold conditionsduring the Late Glacial, while smaller size reflectedclimate warming during the Early Holocene. Weconclude that Cladocera fossils are good indicators ofclimatic change that happened during the transitionfrom the Late Glacial to the Holocene. We found thatclimatic conditions can be tracked either by sizedistribution of Daphnia ephippia (larger ephippiumsize under colder climate) and/or by communitychange of cladocerans.
Tárgyszavak:Természettudományok Környezettudományok idegen nyelvű folyóiratközlemény külföldi lapban
Cladocera remains
Chydorids
Climate change
Mountain lake
Romania
Megjelenés:Hydrobiologia. - 676 : 1 (2011), p. 223-235. -
További szerzők:Magyari Enikő (1973-) (biológus) Buczkó Krisztina (1962-) (biológus) Iepure, Sanda Namiotko, Tadeusz Czakó Dániel Kövér Csilla Braun Mihály (1966-) (vegyész, analitikus)
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3.

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
Dátum:2010
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
diatoms
cladocera remains
trace metals
nyomelemek
chydorids
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)
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4.

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
Dátum:2009
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
románia
pollen
makrofosszília
üledék
vízszint-változás
kovamoszat
alga
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)
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elektronikus változat
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5.

001-es BibID:BIBFORM099141
Első szerző:Schnitchen Csaba
Cím:Micropaleontological observations on a Sphagnum bog in East Carpathian region : testate amoebae (Rhizopoda: Testacea) and their potential use for reconstruction of micro- and macroclimatic changes / Schnitchen Csaba, Magyari Enikő, Tóthmérész Béla, Grigorszky István, Braun Mihály
Dátum:2003
ISSN:0018-8158 1573-5117
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Hydrobiologia. - 506-509 : 1-3 (2003), p. 45-49. -
További szerzők:Magyari Enikő (1973-) (biológus) Tóthmérész Béla (1960-) (ökológus) Grigorszky István (1967-) (biológus-ökológus) Braun Mihály (1966-) (vegyész, analitikus)
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6.

001-es BibID:BIBFORM087671
Első szerző:Szabó Sándor (biológus)
Cím:Decomposition of duckweed (Lemna gibba) under axenic and microbial conditions: flux of nutrients between litter water and sediment, the impact of leaching and microbial degradation / Sándor Szabó, Mihály Braun, Péter Nagy, Sándor Balázsy, Otto Reisinger
Dátum:2000
ISSN:0018-8158 1573-5117
Megjegyzések:The decomposition of axenic Lemna gibba has been studied over a 200 day period under laboratory conditions in the presence and absence of wastewater micro-organisms. The residual mass of plant litter in the decomposition vessels decreased three times more rapidly under biotic than abiotic conditions. The organic matter in the duckweed litter lost about half its weight within 67.9 days in the presence of micro-organisms while more than 200 days were required in axenic vessels. In the former case, AFDW loss followed an exponential pattern of decay. The rate constant was 0.0102 day(-1) and the decay was virtually complete after 200 days. The C and K concentration of the remaining duckweed litter decreased; the N, Ca, Fe and B concentration increased in both treatments. The concentration of total N, P, K, Mg, and Mo increased in the receiving water in both treatments but was much higher under biotic than abiotic conditions. Mass balances of nutrients in the vessels and flux of these nutrients between compartments in the vessels (duckweed litter, water and sediment) have been determined. Under axenic conditions the release of elements was very slow. Only notably potassium leaching had occurred. Leaching of potassium, magnesium and organic carbon took place mainly during the first term of incubation and then slowed down. Under biotic decomposition the elemental content of the litter decreased by more than 50% over 43 days for K, 53 days for Mo, 64 days for C, 81 days for Mg, 101 days for S, 104 days for P, 108 days for Na, 111 days for N, 140 days for B. Calcium and iron immobilised in the litter. Most of the released N, S, P, K, Mg and Mo remained in the water, but B and Mn settled into the sediment. The result of the investigation demonstrated that the nutrient flux from decomposing duckweed litter is mainly a microbially mediated process.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
decomposition
Lemna gibba
wastewater
micro-organisms
leaching
Megjelenés:Hydrobiologia. - 434 : 1/3 (2000), p. 201-210. -
További szerzők:Braun Mihály (1966-) (vegyész, analitikus) Nagy Péter Tamás (1970-) (vegyész) Balázsy Sándor Reisinger, Otto
Pályázati támogatás:F6022
OTKA
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