Biological invasions are a major threat to biodiversity in the Neotropical region. However, few s... more Biological invasions are a major threat to biodiversity in the Neotropical region. However, few studies have evaluated the mechanisms underlying the long-term establishment of fish propagules in aquatic environments. Here, we associated fish biomass, species richness, and proportion of non-native species (contamination index) to quantify propagule and colonisation pressures, and fish biodiversity (measured by the Kempton’s index) in lakes and rivers of the Parana River floodplain. We organised species into native and non-native assemblages sampled by gillnetting and beach seining in spatio-temporal gradients, seasonally, from 2000 to 2017. Native and non-native Kempton’s indices were inversely correlated, native extinctions occurred locally with non-native biotic differentiation in lakes, rivers, and ecosystem contamination. A constant propagule pressure resulted in an overwhelming biodiversity of non-natives at the end of the evaluated time series. Biotic resistance to introduction...
Abstract This study aimed to investigate the match between breeding bird communities’ potential r... more Abstract This study aimed to investigate the match between breeding bird communities’ potential resilience and projections of climate change in Europe. Here we identified European regions with the most substantial projected impacts of climate change based on Δ temperature and Δ precipitation in the next 60 years, assessing the overlap with maps of potential bird community resilience. We combined data on the number of species and functional redundancy of avian communities, to calculate an index of potential community resilience. Finally, combining these three layers of information, we obtained unique large-scale evidence of differences in potential conservation threats in the continent. Approximately 3% of the continent could be exposed to a maximum risk of conservation concern (areas characterized by more significant changes in precipitation and temperatures and simultaneously by avian communities with the lower functional redundancy) by 2070, with a 31% exposed to high risks, and 23% of the continent facing potentially moderate risk. Our findings provide important information on the potential capacity of European breeding bird communities to reduce the negative impact of changes in climate (temperature and precipitation), as well as identifying those regions potentially facing higher conservation risks (e.g. Southern part of Western Europe and the Ural Mountains in Russia).
Deux campagnes acoustiques distinctes ont montre que les insectes aquatiques peuvent generer des ... more Deux campagnes acoustiques distinctes ont montre que les insectes aquatiques peuvent generer des echos comparables a ceux de petits poissons. Dans deux lacs acides de montagne de la Republique Tcheque, ou les poissons sont absents, une serie d'indices de reflexion individuels, bien definis, a ete observee, ressemblant a ceux des poissons (indices de reflexion a 120 kHz, de -66 a -50 dB). Ces 'cibles' ont ete trouvees entre 5 et 7 m durant le jour (juin-juillet 1997). Durant la nuit, le nombre de cibles est plus eleve, enregistrees au moyen d'un echosondeur en emission horizontale (profondeur < 3 m). Des traits de filets a icthyoplancton effectues a cette profondeur ont revele la presence d'Hemipteres Corixides (punaises aquatiques), du genre Glaeno<.cri.ia pour la plupart. Les indices de reflexion des Corixides ont aussi ete verifies par observation directe en bassin experimental, ou il a ete possible de mesurer les indices de reflexion des cibles en vues laterales, dorsales et ventrales. Dans trois reservoirs hollandais, Petrusplaat, Honderd-en-Dertig et De Gijster (100 a 300 ha, 15 a 28 m de profondeur, avec presence de poissons), les indices de reflexion des cibles telles les pupes de dipteres chironomides (Procladius signatus) remontant en surface, de -74 et -65 dB, ont ete observes par echosondeur emettant verticalement. La presence de pupes a ete verifiee par des traits de filets horizontaux a icthyoplancton et par des traits a plancton verticaux dans le faisceau acoustique. La part des insectes aquatiques par rapport a la biomasse des poissons etait faible mais elle peut interferer lors d'evaluation de poissons juveniles.
The fish fry communities of the upper River Thames and a connected backwater were sampled quantit... more The fish fry communities of the upper River Thames and a connected backwater were sampled quantitatively by a fry seine net in July-August when river flows were very low and the natural marginal vegetation was fully developed. At this time of year, the habitats available to them were (1) clumps of channel plants at the water edge of the littoral vegetation and (2) deep erosion banks without plants. A third characteristic habitat in this river were (3) shallow organically-rich sandy-gravel beaches produced by watering cattle. These three habitats were sampled along a 25 km stretch of the main channel in order to estimate species composition, densities and sizes of their fry communities. A comparable study in a flow-through backwater sited on the original river course showed that fast water flows from an open weir-gate influenced water depths, produced steeper inshore gradients and affected the distribution of the marginal vegetation and the fry communities. The most species-rich and abundant fry communities were found in habitats with a plant cover and in the shallow beaches because they offered both a good food resource and protection from predation. Neither of these was available in the deep erosion banks where few 0+ fish occurred. No 0+ fry occupied the plantless sites in the backwater which were subject to high velocities although even a poor plant cover could offer a refuge against flow for a few species. Roach was the predominant species in the abundant fry communities and its relative abundance explained differences in community structure estimated by Simpson's and Shannon Diversity Indices.
Comparative Reservoir Limnology and Water Quality Management, 1993
Framework for reservoir characterization, water quality sampling, methods for analysis and data e... more Framework for reservoir characterization, water quality sampling, methods for analysis and data evaluation for different parameters are given. The most important drinking water reservoir water quality parameter groups are covered: those related to stratification, to eutrophication, to organic matter changes and to bacterial populations. Simple models and/or quantitative evaluation tables are developed for most parameters. Fish populations are considered important regulator of zooplankton which subsequently regulates phytoplankton. Methods of results recording, processing and evaluation are given, with emphasis on computer storage, basic statistics, trend evaluation, dependence of water quality parameters on flow and material budgets. A new simple method for characterization of reservoir stratification is outlined. Consequences of the results for water quality management are divided into three groups: consequences for the watershed, for the reservoir and for the drinking water treatment plant.
The history of fish, zooplankton and phytoplankton in RimovReservoir during its 14 years existenc... more The history of fish, zooplankton and phytoplankton in RimovReservoir during its 14 years existence is documented. Afterthe filling of the reservoir in autumn 1978, the biomass ofplanktivorous fish increased from near zero to 650 kg ha-1 bythe fourth year of the reservoir‘s existence, after which thefish stock continually decreased under various forms ofbiomanipulative pressure, down to a value of about
Biological invasions are a major threat to biodiversity in the Neotropical region. However, few s... more Biological invasions are a major threat to biodiversity in the Neotropical region. However, few studies have evaluated the mechanisms underlying the long-term establishment of fish propagules in aquatic environments. Here, we associated fish biomass, species richness, and proportion of non-native species (contamination index) to quantify propagule and colonisation pressures, and fish biodiversity (measured by the Kempton’s index) in lakes and rivers of the Parana River floodplain. We organised species into native and non-native assemblages sampled by gillnetting and beach seining in spatio-temporal gradients, seasonally, from 2000 to 2017. Native and non-native Kempton’s indices were inversely correlated, native extinctions occurred locally with non-native biotic differentiation in lakes, rivers, and ecosystem contamination. A constant propagule pressure resulted in an overwhelming biodiversity of non-natives at the end of the evaluated time series. Biotic resistance to introduction...
Abstract This study aimed to investigate the match between breeding bird communities’ potential r... more Abstract This study aimed to investigate the match between breeding bird communities’ potential resilience and projections of climate change in Europe. Here we identified European regions with the most substantial projected impacts of climate change based on Δ temperature and Δ precipitation in the next 60 years, assessing the overlap with maps of potential bird community resilience. We combined data on the number of species and functional redundancy of avian communities, to calculate an index of potential community resilience. Finally, combining these three layers of information, we obtained unique large-scale evidence of differences in potential conservation threats in the continent. Approximately 3% of the continent could be exposed to a maximum risk of conservation concern (areas characterized by more significant changes in precipitation and temperatures and simultaneously by avian communities with the lower functional redundancy) by 2070, with a 31% exposed to high risks, and 23% of the continent facing potentially moderate risk. Our findings provide important information on the potential capacity of European breeding bird communities to reduce the negative impact of changes in climate (temperature and precipitation), as well as identifying those regions potentially facing higher conservation risks (e.g. Southern part of Western Europe and the Ural Mountains in Russia).
Deux campagnes acoustiques distinctes ont montre que les insectes aquatiques peuvent generer des ... more Deux campagnes acoustiques distinctes ont montre que les insectes aquatiques peuvent generer des echos comparables a ceux de petits poissons. Dans deux lacs acides de montagne de la Republique Tcheque, ou les poissons sont absents, une serie d'indices de reflexion individuels, bien definis, a ete observee, ressemblant a ceux des poissons (indices de reflexion a 120 kHz, de -66 a -50 dB). Ces 'cibles' ont ete trouvees entre 5 et 7 m durant le jour (juin-juillet 1997). Durant la nuit, le nombre de cibles est plus eleve, enregistrees au moyen d'un echosondeur en emission horizontale (profondeur < 3 m). Des traits de filets a icthyoplancton effectues a cette profondeur ont revele la presence d'Hemipteres Corixides (punaises aquatiques), du genre Glaeno<.cri.ia pour la plupart. Les indices de reflexion des Corixides ont aussi ete verifies par observation directe en bassin experimental, ou il a ete possible de mesurer les indices de reflexion des cibles en vues laterales, dorsales et ventrales. Dans trois reservoirs hollandais, Petrusplaat, Honderd-en-Dertig et De Gijster (100 a 300 ha, 15 a 28 m de profondeur, avec presence de poissons), les indices de reflexion des cibles telles les pupes de dipteres chironomides (Procladius signatus) remontant en surface, de -74 et -65 dB, ont ete observes par echosondeur emettant verticalement. La presence de pupes a ete verifiee par des traits de filets horizontaux a icthyoplancton et par des traits a plancton verticaux dans le faisceau acoustique. La part des insectes aquatiques par rapport a la biomasse des poissons etait faible mais elle peut interferer lors d'evaluation de poissons juveniles.
The fish fry communities of the upper River Thames and a connected backwater were sampled quantit... more The fish fry communities of the upper River Thames and a connected backwater were sampled quantitatively by a fry seine net in July-August when river flows were very low and the natural marginal vegetation was fully developed. At this time of year, the habitats available to them were (1) clumps of channel plants at the water edge of the littoral vegetation and (2) deep erosion banks without plants. A third characteristic habitat in this river were (3) shallow organically-rich sandy-gravel beaches produced by watering cattle. These three habitats were sampled along a 25 km stretch of the main channel in order to estimate species composition, densities and sizes of their fry communities. A comparable study in a flow-through backwater sited on the original river course showed that fast water flows from an open weir-gate influenced water depths, produced steeper inshore gradients and affected the distribution of the marginal vegetation and the fry communities. The most species-rich and abundant fry communities were found in habitats with a plant cover and in the shallow beaches because they offered both a good food resource and protection from predation. Neither of these was available in the deep erosion banks where few 0+ fish occurred. No 0+ fry occupied the plantless sites in the backwater which were subject to high velocities although even a poor plant cover could offer a refuge against flow for a few species. Roach was the predominant species in the abundant fry communities and its relative abundance explained differences in community structure estimated by Simpson's and Shannon Diversity Indices.
Comparative Reservoir Limnology and Water Quality Management, 1993
Framework for reservoir characterization, water quality sampling, methods for analysis and data e... more Framework for reservoir characterization, water quality sampling, methods for analysis and data evaluation for different parameters are given. The most important drinking water reservoir water quality parameter groups are covered: those related to stratification, to eutrophication, to organic matter changes and to bacterial populations. Simple models and/or quantitative evaluation tables are developed for most parameters. Fish populations are considered important regulator of zooplankton which subsequently regulates phytoplankton. Methods of results recording, processing and evaluation are given, with emphasis on computer storage, basic statistics, trend evaluation, dependence of water quality parameters on flow and material budgets. A new simple method for characterization of reservoir stratification is outlined. Consequences of the results for water quality management are divided into three groups: consequences for the watershed, for the reservoir and for the drinking water treatment plant.
The history of fish, zooplankton and phytoplankton in RimovReservoir during its 14 years existenc... more The history of fish, zooplankton and phytoplankton in RimovReservoir during its 14 years existence is documented. Afterthe filling of the reservoir in autumn 1978, the biomass ofplanktivorous fish increased from near zero to 650 kg ha-1 bythe fourth year of the reservoir‘s existence, after which thefish stock continually decreased under various forms ofbiomanipulative pressure, down to a value of about
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