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Kasprzak P.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Shatwell T.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Gessner M.O.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Gessner M.O.,TU Berlin | And 7 more authors.
Ecosystems | Year: 2017

Climate forecasts project a global increase in extreme weather events, but information on the consequences for ecosystems is scarce. Of particular significance for lakes are severe storms that can influence biogeochemical processes and biological communities by disrupting the vertical thermal structure during periods of stratification. An exceptional storm passing over northern Germany in July 2011 provided an opportunity to assess the consequences and underlying mechanisms of such extreme events on the interplay between the physics and ecological characteristics of a deep, nutrient-poor lake. Wind speeds were among the most extreme on record. A suite of variables measured throughout the event consistently indicates that a cascade of processes pushed the clear-water lake into an exceptionally turbid state. Specifically, thermocline deepening by the storm-entrained cyanobacteria of a deep chlorophyll maximum located at about 8 m depth into the surface mixed layer. Released from light limitation, intense photosynthesis of the cyanobacteria boosted primary production, increased algal biomass, raised the pH and thus induced massive calcite precipitation to a level never observed within three decades of lake monitoring. As a consequence, water transparency dropped from 6.5 to 2.1 m, the minimum on record for 40 years, and the euphotic zone shrank by about 8 m for several weeks. These results show that cyanobacterial blooms not only are promoted by climate warming, but can also be triggered by extreme storms. Clear-water lakes developing a deep chlorophyll maximum appear to be particularly at risk in the future, if such events become more intense or frequent. © 2017 Springer Science+Business Media New York


Tapolczai K.,French National Institute for Agricultural Research | Tapolczai K.,University of Pannonia | Anneville O.,French National Institute for Agricultural Research | Padisak J.,University of Pannonia | And 6 more authors.
Hydrobiologia | Year: 2014

Over the last decades, mass developments by the filamentous conjugating green alga Mougeotia have been followed in three large peri-alpine lakes (Lake Geneva, Lake Garda, Lake Maggiore) and in the sub-tropical Lake Kinneret. The aim of this study is to highlight annual and interannual patterns of Mougeotia biomass in the studied lakes and select key environmental parameters that may favour and maintain its mass development. Our results confirm former studies that planktic Mougeotia favours meso-oligotrophic conditions and becomes dominant when annual mean total phosphorus concentrations in the epilimnion fall below 20 µg l−1. This triggering factor has effect with interactions of other environmental circumstances such as the water column stability. Physiological and morphological features of the taxon make it a successful competitor under stratified conditions. Results also showed that in three out of the four studied lakes, the annual peak was higher when the annual population development started earlier. Focusing on Lake Geneva, depth and strength of the thermocline, as well as wind speed in the beginning of summer that can cause nutrient replenishment and mix the epilimnion are key factors in the blooming of the taxon. © 2014, Springer International Publishing Switzerland 2014.


Dadheech P.K.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Dadheech P.K.,Central University of Rajasthan | Selmeczy G.B.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Selmeczy G.B.,University of Pannonia | And 8 more authors.
Toxins | Year: 2014

Massive developments of potentially toxic cyanobacteria in Lake Stechlin, an oligo-mesotrophic lake in the Baltic Lake District of Germany raised concerns about toxic contamination of these important ecosystems. Field samples in the phase of mass developments of cyanobacteria were used for genetic and toxicological analyses. Microcystins and microcystin genes were detected in field samples of the lake for the first time. However, the toxins were not produced by the dominant taxa (Dolichospermum circinale and Aphanizomenon flos-aquae) but by taxa, which were present only in low biomass in the samples (Microcystis cf. aeruginosa and Planktothrix rubescens). The phytoplankton successions during the study period revealed an increase of cyanobacterial populations. The findings contribute to the changes that have been investigated in Lake Stechlin since the mid-1990s. The possible reasons behind these developments may be climate change, special weather conditions and an increased nutrient pool. © 2014 by the authors; licensee MDPI, Basel, Switzerland.


Naselli-Flores L.,University of Palermo | Padisak J.,University of Pannonia | Padisak J.,MTA PE Limnoecology Research Group
Hydrobiologia | Year: 2015

The selected theme of the 17th Workshop of the International Association for Phytoplankton Taxonomy and Ecology (IAP), “Biogeography and Spatial Patterns of Biodiversity of Freshwater Phytoplankton,” offered the opportunity to explore one neglected aspect of phytoplankton ecology: the distribution of species in the geographic space. This paper summarizes the outcomes of 20 selected contributions among those presented at the workshop. The articles report the results from studies carried out in five continents (only Oceania is not represented) and on a wide array of aquatic ecosystems (deep and shallow natural lakes, man-made lakes, temporary and permanent ponds, rivers). The topics analyzed by the contributors are related to Island Biogeography paradigms, dispersal vectors, survival strategies, environmental filters, dispersal distances, vertical and horizontal spatial variability of phytoplankton between and within water bodies, and of course, invasive algae. The overall analysis of the results presented clearly demonstrates that, as for many others organisms, there are “rules” governing freshwater phytoplankton spatial patterns and that these organisms also have a true biogeography, as nowadays is quite evident for several other groups in the same range of size. We can definitively conclude that the statement “Everything is everywhere” is obsolete, even though human activities tend to homogenize species distribution in the biosphere. © 2015 Springer International Publishing Switzerland


Yang Y.,Uppsala University | Stenger-Kovacs C.,University of Pannonia | Padisak J.,University of Pannonia | Padisak J.,MTA PE Limnoecology Research Group | Pettersson K.,Uppsala University
Hydrobiologia | Year: 2016

Phytoplankton seasonal succession has been linked to a variety of serial environmental changes, especially weather- and climate-induced physical forcing. This study compared spring phytoplankton dynamics after winters of different severity (cold, normal, and warm) in Lake Erken, Sweden. The spring diatom bloom was dominated by different functional groups: group A (centric diatoms 5–10 μm) after cold winters, B (centric diatoms >15 μm) after normal winters, and P (Aulacoseira granulata, Fragilaria crotonensis) after warm winters. Our results suggest that weather-related processes were the primary external drivers accounting for differences in spring phytoplankton dynamics in Lake Erken. Spring phytoplankton are influenced by overwintering species from the last autumn that can initiate the following spring bloom. Average taxonomic distinctness of the spring community was assessed using a new biodiversity measurement that incorporates taxonomic relatedness information. This value was lower than expected after warm and cold winters, which had winter air temperature 1°C deviation from an average value calculated over 21 years. Such winters increased the level of disturbance or stress to the lake, resulting in a spring with less diverse phytoplankton by narrowing the niche for species with various ecological requirements. © 2016 Springer International Publishing Switzerland


Hu R.,Jinan University | Li Q.,Guizhou Normal University | Han B.-P.,Jinan University | Naselli-Flores L.,University of Palermo | And 3 more authors.
Hydrobiologia | Year: 2015

Water quality improvement and suppression of cyanobacterial blooms were planned in a eutrophic reservoir in southern China through ecological engineering measures from 2006 to 2011. This consisted in (i) a hydraulic resetting of inflows and outflows to increase the distance between inlet and outlet and the water residence time in the reservoir, and in (ii) the installation of floating frames hosting wetland vegetation to promote an alteration in phytoplankton composition. The environmental changes were therefore followed through the analysis of biotic responses in phytoplankton assemblages. Ecological engineering was effective in reducing phytoplankton total biomass, in re-establishing more diversified phytoplankton assemblages and in avoiding cyanobacterial blooms. These changes may be considered as an improvement of the reservoir water quality. However, trophic state parameters and the dynamics of dominant species were not sensitive enough in describing the environmental changes that had occurred when the eco-engineering measures were implemented. These were more effectively tracked by the dynamics followed by phytoplankton Morpho-Functional-Groups and by their classification based on Competitors, Stress tolerants and Ruderals strategies. Although providing immediate positive effects, the eco-engineering was temporally limited, highlighting the importance of constant management in the context of long-term oriented remediation techniques. © 2015 Springer International Publishing Switzerland


Bede-Fazekas A.,Corvinus University of Budapest | Horvath L.,Corvinus University of Budapest | Trajer A.J.,University of Pannonia | Trajer A.J.,MTA PE Limnoecology Research Group | Gregorics T.,Eötvös Loránd University
Applied Artificial Intelligence | Year: 2015

This article is about the development and application of an ESRI ArcGIS tool that implements a multilayer, feed-forward artificial neural network (ANN) to study the climate envelopes of species. The supervised learning is achieved by a backpropagation algorithm. Based on the distribution and the grids of the climate (and edaphic data) of the reference and future periods, the tool predicts the future potential distribution of the studied species. The trained network can be saved and loaded. A modeling result based on the distribution of European larch (Larix decidua Mill.) is presented as a case study. Copyright © 2015 Taylor & Francis Group, LLC.


Tapolczai K.,Thonon les Bains | Bouchez A.,Thonon les Bains | Stenger-Kovacs C.,University of Pannonia | Padisak J.,University of Pannonia | And 2 more authors.
Hydrobiologia | Year: 2016

A high number of species often represents a relevant redundancy in terms of ecological adaptation strategies. Collecting species to groups based on their functional adaptations can handle this redundancy and obtain the “real” functional complexity of ecosystems. Functional traits are proxies of adaptation strategies under particular environmental conditions, and a set of functional traits are interpreted as life-strategies. Organisms with life-strategies occupying a similar niche can be collected in ecological groups (functional group/guild). In this study, we review the latest trait-based approaches and existing attempts at functional classifications in phytobenthos studies. Advantages and shortcomings of these classifications are discussed with perspectives of their utility in ecological status assessment. © 2016 Springer International Publishing Switzerland


Trajer A.,University of Pannonia | Trajer A.,MTA PE Limnoecology Research Group | Hammer T.,University of Pannonia
Idojaras | Year: 2016

The potential resurgence of malaria in the temperate areas of Europe due to climate change is an actual topic of epidemiology. Although several ecological forecasting models were built for the prediction of the potential re-emergence of malaria in the recently non-endemic areas of the world, the simulations are mainly based on the recent climatic thresholds of the tropical and subtropical vectors and Plasmodium parasites, mainly of Plasmodium falciparum. We aimed to reanalyze the primarily Plasmodium vivax caused autochthon malaria disease data of the past model period of 1927-1934 in Hungary to gain reliable knowledge about the climatic thresholds and the determinants of the malaria season for a temperate climate in a Central European country. Multivariable and simple linear correlation and regression was performed to analyze the malaria data of 96 months dividing the season a first and a second half parts of the year. Two models were built on the gained correlations using unstandardized and standardized correlation weights. It was found, that both in the first and second halves of the year, the ambient mean temperature was the most important predictor of the relative malaria incidence, while precipitation influenced the first half of the season. Summer sum of precipitation above 200 mm was found as one of the most important determinant of the absolute annual case number of benign tertian malaria. The unstandardized weights-based modeled malaria seasons returned well the observed autochthon malaria seasons. © 2016, Hungarian Meteorological Service. All rights reserved.


Yang Y.,Uppsala University | Pettersson K.,Uppsala University | Padisak J.,University of Pannonia | Padisak J.,MTA PE Limnoecology Research Group
Hydrobiologia | Year: 2015

The seasonal development of phytoplankton is a sequence of consecutive events with waxes and wanes of biomass and compositional shifts. This study analyzed 16 years data in Lake Erken, Sweden and revealed four baselines of phytoplankton succession with their underlying drivers. Results showed that there were two diatom-dominated phases annually. The vernal community was dominated by centric diatoms larger than 15 µm (functional groups B and C) which were fast-growing diatoms being highly efficient in the use of nutrients. The autumn community was comprised mainly meroplanktonic mixing-dependent Aulacoseira granulata and Fragilaria sp. (MP and P) or/and large centric diatoms (B). Between the two mixing-phases with diatoms, a Gloeotrichia echinulata (H2) bloom occurred due to its preference for a stratified water column with elevated water temperatures and high light availability. The summer stratification in Lake Erken was weak and short, thus, favoring meroplanktonic diatoms to peak once the lake turned over in early autumn. Lake Erken represents an intermediate case between a highly mixed polymictic lake and a lake with strong summer stratification, where the observed stratification patterns allowed the development of an autumn diatom phase similar, by extent, to the vernal one and mainly dominated by meroplanktonic diatoms. © 2015 Springer International Publishing Switzerland

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