Világszerte egyre inkább növekednek az aszályos időszakok, jelentősen csökkentek az állóvizeink v... more Világszerte egyre inkább növekednek az aszályos időszakok, jelentősen csökkentek az állóvizeink vízszintjei. Paleolimnológiai vizsgálatok esetében az állóvizek üledékének tanulmányozása folyik, melynek segítségével a múltban lejátszódott folyamatok, illetve környezeti hatások elemzésére adódik lehetőség. Paleolimnológiai kutatások során, amikor az üledékben megőrződött szervezetek maradványait, beleértve a Cladocera maradványokat vizsgáljuk, a meder legmélyebb részéről szoktunk üledék mintát venni, mert a legmélyebb pontra sodródnak össze a maradványok. Hazánkban azonban a legnagyobb számban sekély vízterek fordulnak elő, így vizsgálatunk célja az volt, hogy megnézzük, sekély vízterek esetében célszerűbb lenne-e a több mintavételi pont kijelölése? A mintavételekre hat vízteret jelöltünk ki és mindegyik víztérből három mintát vettünk, úgy, hogy a mintavételi helyek legalább 75-100 m távolságban helyezkedjenek el egymástól. A medrekben a habitatok is hasonlóak voltak. Az eredmények az...
Here we report and document the occurrence of the diatom Gomphonema lacunicola Patrick et Freese ... more Here we report and document the occurrence of the diatom Gomphonema lacunicola Patrick et Freese 1961 from the Pâreng Mts of the Carpathian Mountains, Romania. This observation was made within the framework of a systematic sampling campaign and analyses that were conducted in the Southern Carpathians, covering 40 mountain lakes for discovering the cladoceran fauna and diatom flora of this region between 2012 and 2014. G. lacunicola was found only in one of the 40 lakes, namely in Lake Câlcescu, where it was extremely rare, but the characteristic feature of the lake promoted the presence of the species. Lake Câlcescu is a subalpine lake, located 1,934 m a.s.l. This is the first record of this diatom species in Romania.
Cladocerans are biological indicators of environmental changes. Their remains provide information... more Cladocerans are biological indicators of environmental changes. Their remains provide information on past changes in lake environments. We studied the correspondence between contemporary Cladocera assemblages and their subfossil remains from an oxbow lake. We sought to demonstrate that there were differences among the various sites of an oxbow lake with different utilization based on contemporary and subfossil Cladocera assemblages and physical–chemical variables. The oxbow lake’s two sides are used as fishing sites, where angling is the main activity. The middle site of the lake is under nature protection with high macrovegetation coverage. Contemporary and subfossil Cladocera assemblages were sampled from 21 sampling sites along the oxbow lake. Our research showed that the subfossil Cladocera assemblages had higher species richness and densities (36 taxa) than the contemporary species (29 taxa). We found one species of the Polyphemidae family only in the contemporary assemblage. A...
Here we report and document the first Romanian occurrence of the diatom Gomphonema angustivalva E... more Here we report and document the first Romanian occurrence of the diatom Gomphonema angustivalva E. Reichardt 1997 from a proglacial lake of the Carpathian Mts. Identifying this narrow-valved gomphonemoid taxon (valva width < 5 μm) requires the exploration of ultrastructure using scanning electron microscopy. We observed the species in the material collected from a lake sediment core of Lake Bâlea (Romania).
Studying local extinction times, associated environmental and human population changes during the... more Studying local extinction times, associated environmental and human population changes during the last glacial termination provides insights into the causes of mega- and microfauna extinctions. In East-Central (EC) Europe, Palaeolithic human groups were present throughout the last glacial maximum (LGM), but disappeared suddenly around 15 200 cal yr BP. In this study we use radiocarbon dated cave sediment profiles and a large set of direct AMS 14C dates on mammal bones to determine local extinction times that are compared with the Epigravettian population decline, quantitative climate models, pollen and plant macrofossil inferred climate and biome reconstructions and coprophilous fungi derived total megafauna change for EC Europe. Our results suggest that the population size of large herbivores decreased in the area after 17 700 cal yr BP, when temperate tree abundance and warm continental steppe cover both increased in the lowlands Boreal forest expansion took place around 16 200 ca...
&amp;amp;amp;amp;lt;p&amp;amp;amp;amp;gt;Over the last 10 years several alpine lakes were... more &amp;amp;amp;amp;lt;p&amp;amp;amp;amp;gt;Over the last 10 years several alpine lakes were studied from the Southern Carpathian Mountains (SCM) using paleoecological, geochemical and stable isotope techniques. The aim of these studies were to obtain quantitative climate reconstructions for the alpine region for the Late Glacial (LG) and Holocene, reconstruct tree and timberline changes and examine how rapid climate change events manifested in this region, what are the regions characteristics. Absolute chronologies were also supported here for the first time with tephra chronology in the Early Holocene. In addition, environmental DNA studies were used to explore what molecular techniques can add to a more exact and often species level reconstruction of past floristic compositions. This talk will summarize these researches and use multivariate statistics to examine leads and lags in ecosystem response at multiple sites (Retezat, Pareng, Fogaras, Ciomadul Mts). These analyses first of all demonstrate that the amplitude of warming was attenuated in the SCM at the GS-2/GI-1 transition relative to NW Europe (~2,8-3 &amp;amp;amp;amp;lt;sup&amp;amp;amp;amp;gt;o&amp;amp;amp;amp;lt;/sup&amp;amp;amp;amp;gt;C), summer temperatures increased abruptly already at 16.2 ka cal BP in direct response to the weakening polar circulation and the tripartite GS-1 had weak summer temperature decrease (&amp;amp;amp;amp;lt;1 &amp;amp;amp;amp;lt;sup&amp;amp;amp;amp;gt;o&amp;amp;amp;amp;lt;/sup&amp;amp;amp;amp;gt;C), but winter cooling was strong. Regarding the order of ecosystem changes, lead and lag analysis revealed &amp;amp;amp;amp;lt;50 yr lag in vegetation response, 0-100 lag in aquatic floristic response and ~100-150 yr lag in aquatic faunal response to external forcing. Environmental DNA studies showed that despite the method is capable to better capture grass (Poaceae) floristic diversity and replicates woody specie composition obtained by plant macrofossil data, it fails to provide higher resolution for the herbaceous flora around the studied lakes that feature was explained partly by the incompleteness of reference DNA sequences for the trnL region and the DNA preservation characteristics of alpine lakes. Using these pioneer studies, several promising research directions were identified for this region: modelling of projected tree and timberline changes in combination with reconstructed data, using eDNA techniques to decipher alpine farming histories in the mountains and its impact on late Holocene tree and timberline change, reconstruction the accelerating speed of ecosystem change over the last 100 yr. in alpine lakes and calling attention for the irreversibility of these changes, demonstrating tipping points. These will be discussed in the presentation.&amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;gt;
The body size of aquatic invertebrates is, to a great extent, dependent on ambient temperature, b... more The body size of aquatic invertebrates is, to a great extent, dependent on ambient temperature, but size distributions are also determined by other factors like food supply and predation. The effect of temperature on organisms is formulated in the temperature–size hypothesis, which predicts a smaller body size with increasing temperature. In this study, the effect of temperature on the subfossil remains of three littoral Cladocera (Alona affnis, A. quadrangularis, and Chydorus cf. sphaericus) was investigated. Exoskeletal remains of these species can be found in large numbers in lacustrine sediments and over a wide north–south range in Europe. The total length of both headshield and postabdomen for A. affinis and A. quadrangularis and carapace length for C. cf. sphaericus were measured to observe their response to changes in latitude and temperature. A different response to ambient temperature in the growth of body parts was observed. The size of the headshields of both Alona specie...
Here we report the results of our decades-long study on epiphytic communities from two tributary ... more Here we report the results of our decades-long study on epiphytic communities from two tributary systems of the Szigetköz section of the Danube River. The main goal of the investigation was to detect changes in the epiphytic communities at structural (core species, changes in the relative abundance of common species) and functional (trait changes) levels as a result of the most important anthropogenic effects on Szigetköz, i.e., hydro-morphological modifications. We also examined the impact of rehabilitation on the tributary systems in terms of ecological potential. We discovered that mainly motile diatom species characterized the epiphyton due to reduced water volume were introduced into the tributary system after the diversion of the Danube. The ecosystem stabilized in the rehabilitated section, while the non-rehabilitated section showed a worsening tendency, mainly in the parapotamic branches. Our long-term data sets may provide a good basis for comparisons of different aquatic e...
Saline lakes, among the most seriously endangered ecosystems, are threatened due to climate chang... more Saline lakes, among the most seriously endangered ecosystems, are threatened due to climate change and human activities. One valuable feature of these environments is that they constitute areas of high biodiversity. Ecologists are, therefore, under great pressure to improve their understanding of the effects of natural and anthropogenic disturbances on the biodiversity of saline lakes. In this study, a total of 257 samples from 32 soda pans in Central Europe between 2006 and 2015 were examined. The effects of environmental variables and of geographical and limnoecological factors on functional diversity were analyzed. Furthermore, the explanatory power of the trait‐based approach was assessed, and the applicability of the indices for biomonitoring purposes was determined. It was found that low habitat heterogeneity and harsh environments lead to the selection of a small number of suitable traits, and consequently, to a naturally low level of functional diversity. Anthropogenic activ...
Studying contemporary and subfossil Cladocera (Crustacea) communities, we explored the effect of ... more Studying contemporary and subfossil Cladocera (Crustacea) communities, we explored the effect of top-down stressors on the cladoceran communities; we are also interested in the coherence of the contemporary and subfossil communities. The studied Cibakháza oxbow lake is in E Hungary, on the left-floodplain of the River Tisza; it is a large, long, and shallow oxbow lake. Three areas of the oxbow lake were distinguished based on the strength of top-down stress: protected area with low top-down stress, biomanipulated area with high top-down stress, and recreational area with moderate top-down stress. Altogether, we identified 28 taxa in the contemporary and subfossil communities in the oxbow lake. We found that the species number of the contemporary Cladocera communities was lower (protected area: 13; biomanipulated area: 9, and recreational area: 14) than in the subfossil communities (protected area: 20; biomanipulated area: 16, and recreational area: 14). Among the environmental varia...
Diadesmis fukushimae, a rare oligotraphenic diatom, was found in some high mountain lakes of Roma... more Diadesmis fukushimae, a rare oligotraphenic diatom, was found in some high mountain lakes of Romania. Its occurrence in the Parâng and Retezat Mountains is the second European record of the species. To date D. fukushimae has been known only from the type locality (Shenandoah National Park, Virginia, USA) and from a spring (Grotta Guernica, Dolomiti Bellunesi National Park (south-eastern Alps, Italy). Investigation by scanning electron microscopy showed that this species should be transferred to the recently established genus Humidophila. A new combination is proposed, Humidophila fukushimae. The morphological details of the European population are also presented.
Világszerte egyre inkább növekednek az aszályos időszakok, jelentősen csökkentek az állóvizeink v... more Világszerte egyre inkább növekednek az aszályos időszakok, jelentősen csökkentek az állóvizeink vízszintjei. Paleolimnológiai vizsgálatok esetében az állóvizek üledékének tanulmányozása folyik, melynek segítségével a múltban lejátszódott folyamatok, illetve környezeti hatások elemzésére adódik lehetőség. Paleolimnológiai kutatások során, amikor az üledékben megőrződött szervezetek maradványait, beleértve a Cladocera maradványokat vizsgáljuk, a meder legmélyebb részéről szoktunk üledék mintát venni, mert a legmélyebb pontra sodródnak össze a maradványok. Hazánkban azonban a legnagyobb számban sekély vízterek fordulnak elő, így vizsgálatunk célja az volt, hogy megnézzük, sekély vízterek esetében célszerűbb lenne-e a több mintavételi pont kijelölése? A mintavételekre hat vízteret jelöltünk ki és mindegyik víztérből három mintát vettünk, úgy, hogy a mintavételi helyek legalább 75-100 m távolságban helyezkedjenek el egymástól. A medrekben a habitatok is hasonlóak voltak. Az eredmények az...
Here we report and document the occurrence of the diatom Gomphonema lacunicola Patrick et Freese ... more Here we report and document the occurrence of the diatom Gomphonema lacunicola Patrick et Freese 1961 from the Pâreng Mts of the Carpathian Mountains, Romania. This observation was made within the framework of a systematic sampling campaign and analyses that were conducted in the Southern Carpathians, covering 40 mountain lakes for discovering the cladoceran fauna and diatom flora of this region between 2012 and 2014. G. lacunicola was found only in one of the 40 lakes, namely in Lake Câlcescu, where it was extremely rare, but the characteristic feature of the lake promoted the presence of the species. Lake Câlcescu is a subalpine lake, located 1,934 m a.s.l. This is the first record of this diatom species in Romania.
Cladocerans are biological indicators of environmental changes. Their remains provide information... more Cladocerans are biological indicators of environmental changes. Their remains provide information on past changes in lake environments. We studied the correspondence between contemporary Cladocera assemblages and their subfossil remains from an oxbow lake. We sought to demonstrate that there were differences among the various sites of an oxbow lake with different utilization based on contemporary and subfossil Cladocera assemblages and physical–chemical variables. The oxbow lake’s two sides are used as fishing sites, where angling is the main activity. The middle site of the lake is under nature protection with high macrovegetation coverage. Contemporary and subfossil Cladocera assemblages were sampled from 21 sampling sites along the oxbow lake. Our research showed that the subfossil Cladocera assemblages had higher species richness and densities (36 taxa) than the contemporary species (29 taxa). We found one species of the Polyphemidae family only in the contemporary assemblage. A...
Here we report and document the first Romanian occurrence of the diatom Gomphonema angustivalva E... more Here we report and document the first Romanian occurrence of the diatom Gomphonema angustivalva E. Reichardt 1997 from a proglacial lake of the Carpathian Mts. Identifying this narrow-valved gomphonemoid taxon (valva width < 5 μm) requires the exploration of ultrastructure using scanning electron microscopy. We observed the species in the material collected from a lake sediment core of Lake Bâlea (Romania).
Studying local extinction times, associated environmental and human population changes during the... more Studying local extinction times, associated environmental and human population changes during the last glacial termination provides insights into the causes of mega- and microfauna extinctions. In East-Central (EC) Europe, Palaeolithic human groups were present throughout the last glacial maximum (LGM), but disappeared suddenly around 15 200 cal yr BP. In this study we use radiocarbon dated cave sediment profiles and a large set of direct AMS 14C dates on mammal bones to determine local extinction times that are compared with the Epigravettian population decline, quantitative climate models, pollen and plant macrofossil inferred climate and biome reconstructions and coprophilous fungi derived total megafauna change for EC Europe. Our results suggest that the population size of large herbivores decreased in the area after 17 700 cal yr BP, when temperate tree abundance and warm continental steppe cover both increased in the lowlands Boreal forest expansion took place around 16 200 ca...
&amp;amp;amp;amp;lt;p&amp;amp;amp;amp;gt;Over the last 10 years several alpine lakes were... more &amp;amp;amp;amp;lt;p&amp;amp;amp;amp;gt;Over the last 10 years several alpine lakes were studied from the Southern Carpathian Mountains (SCM) using paleoecological, geochemical and stable isotope techniques. The aim of these studies were to obtain quantitative climate reconstructions for the alpine region for the Late Glacial (LG) and Holocene, reconstruct tree and timberline changes and examine how rapid climate change events manifested in this region, what are the regions characteristics. Absolute chronologies were also supported here for the first time with tephra chronology in the Early Holocene. In addition, environmental DNA studies were used to explore what molecular techniques can add to a more exact and often species level reconstruction of past floristic compositions. This talk will summarize these researches and use multivariate statistics to examine leads and lags in ecosystem response at multiple sites (Retezat, Pareng, Fogaras, Ciomadul Mts). These analyses first of all demonstrate that the amplitude of warming was attenuated in the SCM at the GS-2/GI-1 transition relative to NW Europe (~2,8-3 &amp;amp;amp;amp;lt;sup&amp;amp;amp;amp;gt;o&amp;amp;amp;amp;lt;/sup&amp;amp;amp;amp;gt;C), summer temperatures increased abruptly already at 16.2 ka cal BP in direct response to the weakening polar circulation and the tripartite GS-1 had weak summer temperature decrease (&amp;amp;amp;amp;lt;1 &amp;amp;amp;amp;lt;sup&amp;amp;amp;amp;gt;o&amp;amp;amp;amp;lt;/sup&amp;amp;amp;amp;gt;C), but winter cooling was strong. Regarding the order of ecosystem changes, lead and lag analysis revealed &amp;amp;amp;amp;lt;50 yr lag in vegetation response, 0-100 lag in aquatic floristic response and ~100-150 yr lag in aquatic faunal response to external forcing. Environmental DNA studies showed that despite the method is capable to better capture grass (Poaceae) floristic diversity and replicates woody specie composition obtained by plant macrofossil data, it fails to provide higher resolution for the herbaceous flora around the studied lakes that feature was explained partly by the incompleteness of reference DNA sequences for the trnL region and the DNA preservation characteristics of alpine lakes. Using these pioneer studies, several promising research directions were identified for this region: modelling of projected tree and timberline changes in combination with reconstructed data, using eDNA techniques to decipher alpine farming histories in the mountains and its impact on late Holocene tree and timberline change, reconstruction the accelerating speed of ecosystem change over the last 100 yr. in alpine lakes and calling attention for the irreversibility of these changes, demonstrating tipping points. These will be discussed in the presentation.&amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;gt;
The body size of aquatic invertebrates is, to a great extent, dependent on ambient temperature, b... more The body size of aquatic invertebrates is, to a great extent, dependent on ambient temperature, but size distributions are also determined by other factors like food supply and predation. The effect of temperature on organisms is formulated in the temperature–size hypothesis, which predicts a smaller body size with increasing temperature. In this study, the effect of temperature on the subfossil remains of three littoral Cladocera (Alona affnis, A. quadrangularis, and Chydorus cf. sphaericus) was investigated. Exoskeletal remains of these species can be found in large numbers in lacustrine sediments and over a wide north–south range in Europe. The total length of both headshield and postabdomen for A. affinis and A. quadrangularis and carapace length for C. cf. sphaericus were measured to observe their response to changes in latitude and temperature. A different response to ambient temperature in the growth of body parts was observed. The size of the headshields of both Alona specie...
Here we report the results of our decades-long study on epiphytic communities from two tributary ... more Here we report the results of our decades-long study on epiphytic communities from two tributary systems of the Szigetköz section of the Danube River. The main goal of the investigation was to detect changes in the epiphytic communities at structural (core species, changes in the relative abundance of common species) and functional (trait changes) levels as a result of the most important anthropogenic effects on Szigetköz, i.e., hydro-morphological modifications. We also examined the impact of rehabilitation on the tributary systems in terms of ecological potential. We discovered that mainly motile diatom species characterized the epiphyton due to reduced water volume were introduced into the tributary system after the diversion of the Danube. The ecosystem stabilized in the rehabilitated section, while the non-rehabilitated section showed a worsening tendency, mainly in the parapotamic branches. Our long-term data sets may provide a good basis for comparisons of different aquatic e...
Saline lakes, among the most seriously endangered ecosystems, are threatened due to climate chang... more Saline lakes, among the most seriously endangered ecosystems, are threatened due to climate change and human activities. One valuable feature of these environments is that they constitute areas of high biodiversity. Ecologists are, therefore, under great pressure to improve their understanding of the effects of natural and anthropogenic disturbances on the biodiversity of saline lakes. In this study, a total of 257 samples from 32 soda pans in Central Europe between 2006 and 2015 were examined. The effects of environmental variables and of geographical and limnoecological factors on functional diversity were analyzed. Furthermore, the explanatory power of the trait‐based approach was assessed, and the applicability of the indices for biomonitoring purposes was determined. It was found that low habitat heterogeneity and harsh environments lead to the selection of a small number of suitable traits, and consequently, to a naturally low level of functional diversity. Anthropogenic activ...
Studying contemporary and subfossil Cladocera (Crustacea) communities, we explored the effect of ... more Studying contemporary and subfossil Cladocera (Crustacea) communities, we explored the effect of top-down stressors on the cladoceran communities; we are also interested in the coherence of the contemporary and subfossil communities. The studied Cibakháza oxbow lake is in E Hungary, on the left-floodplain of the River Tisza; it is a large, long, and shallow oxbow lake. Three areas of the oxbow lake were distinguished based on the strength of top-down stress: protected area with low top-down stress, biomanipulated area with high top-down stress, and recreational area with moderate top-down stress. Altogether, we identified 28 taxa in the contemporary and subfossil communities in the oxbow lake. We found that the species number of the contemporary Cladocera communities was lower (protected area: 13; biomanipulated area: 9, and recreational area: 14) than in the subfossil communities (protected area: 20; biomanipulated area: 16, and recreational area: 14). Among the environmental varia...
Diadesmis fukushimae, a rare oligotraphenic diatom, was found in some high mountain lakes of Roma... more Diadesmis fukushimae, a rare oligotraphenic diatom, was found in some high mountain lakes of Romania. Its occurrence in the Parâng and Retezat Mountains is the second European record of the species. To date D. fukushimae has been known only from the type locality (Shenandoah National Park, Virginia, USA) and from a spring (Grotta Guernica, Dolomiti Bellunesi National Park (south-eastern Alps, Italy). Investigation by scanning electron microscopy showed that this species should be transferred to the recently established genus Humidophila. A new combination is proposed, Humidophila fukushimae. The morphological details of the European population are also presented.
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