Debrecen, Hungary
Debrecen, Hungary

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Harka A.,Hungarian Ichthyological Society | Csipkes R.,BioAqua Pro Ltd | Kovacs P.,Middle Tisza District Environment and Water Directorate | Juhasz L.,Debrecen University
Studia Universitatis Vasile Goldis Arad, Seria Stiintele Vietii | Year: 2014

Because of the damming the rheophilic species (Acipenser ruthenus, Barbus barbus) quickly left the area but the populations of eurytopic and stagnophilic species have started to grow. Some populations’ growth was slow and balanced (Tinca tinca), some was quick and exponential (Abramis brama). The changes in the population dynamics were more intense than what the new ecological conditions could explain. Positive amplitude could be seen in the population size of Abramis brama and Esox lucius, negative in Blicca bjoerkna and Abramis sapa. But the extreme changes in the population sizes were followed by a reverse process.The Lake Tisza is a reservoir with an area of 127 square km, created by damming of River Tisza. The reservoir has two major areas: the river bed of the Tisza and the reservoir filled in 1978. In this area 55 fish species have been identified since 1970.The phytophilic fish species found very good spawning areas and enough to feed in a few years after the first flooding of the reservoir. As a result, the catch increased. After a few years the terrestrial vegetation disappeared and the amount of aquatic weeds increased. Because of these effects and the continuous sedimentation the fish production decreased. Nowadays human interventions are needed to slow down the succession of the artificial ecosystem. © 2014 Vasile Goldis University Press.


PubMed | Ferenc Rakoczi Ii Transcarpathian Hungarian Institute, BioAqua Pro LTD, Kossuth Lajos Secondary Grammar School, Mta Of Biodiversity And Ecosystem Services Research Group and Debrecen University
Type: | Journal: Ecotoxicology and environmental safety | Year: 2016

Odonata larvae are frequently used to assess the contamination of aquatic systems, because they tolerate a wide range of chemical and biological conditions in freshwater systems. In early 2000, the sediments of the Hungarian section of the River Tisza and the River Szamos were strongly enriched with heavy metals by an accidental mining spill. Earlier studies demonstrated higher contamination levels in the Szamos than in the Tisza, based on sediment analysis. The aim of our study was to assess the contamination in the Upper Tisza Region, along the upper reach of the Tisza, and the lower reach of the Szamos, based on the trace element concentrations of the Gomphus flavipes larvae. We collected 269 dragonfly specimens for the analyses. The Al, Ba, Cr, Cu, Fe, Mn, Pb, Sr and Zn element contents were analysed in the dragonfly larvae by microwave plasma atomic emission spectrometry (MP-AES). Significantly higher Ba and Cu concentrations were found in the dragonfly larvae of the Tisza than the Szamos. In spite of this, the Cr, Mn, Pb, Sr and Zn concentration was significantly lower in the dragonfly larvae of the Tisza than the Szamos. For all trace elements significant differences were found along the Tisza. Significant differences were also found in all trace element concentrations of dragonfly larvae among studied localities in the Szamos, except in the cases of Al and Ba. Our results demonstrated that the Szamos was more contaminated with Cr, Mn, Pb, Sr and Zn than the Tisza, but that the Tisza was more contaminated with Ba and Cu than the Szamos, based on the trace element concentrations in Gomphus flavipes larvae, which was likely to have been caused by the tributaries of the Tisza. In summary, our results indicated a continuous pollution of the Tisza and the Szamos and their tributaries.


Toth M.,Balaton Limnological Research Institute | Mora A.,Balaton Limnological Research Institute | Kiss B.,BioAqua Pro Ltd. | Devai G.,Debrecen University | Specziar A.,Balaton Limnological Research Institute
European Journal of Entomology | Year: 2012

In this study we evaluate how variations in taxonomic composition and physical structure of macrophyte stands affect plant-dwelling chironomid assemblages in highly variable macrophyte assemblages in two densely vegetated backwaters. By using multivariate explanatory techniques we found that similar vegetation composition did not unequivocally relate to similar chironomid assemblages, moreover the diversity of macrophyte stands did not correlate with the taxonomic diversity of chironomid assemblages in the backwaters investigated. Taxonomic composition and structural characteristics of the vegetation had little influence on the taxonomic or functional (i.e. feeding groups) composition of chironomid assemblages inhabiting them. Similarly, there are only weak relationships between the distribution of certain chironomid species or functional feeding groups and the environmental variables investigated. In general, the structure of the vegetation was more closely associated with the distribution of dominant chironomid taxa than compositional variables (i.e. density of specific macrophyte taxa). In summary, the structure of aquatic vegetation (i.e. position, size of a stand of vegetation, total plant density) and characteristics of the environment where it develops may be more important in shaping plant-dwelling chironomid assemblages than the taxonomic composition of the vegetation.


Mora A.,Balaton Limnological Research Institute | Juhasz P.,BioAqua Pro Ltd. | Kiss B.,BioAqua Pro Ltd. | Muller Z.,BioAqua Pro Ltd. | Malnas K.,BioAqua Pro Ltd.
Zootaxa | Year: 2014

Two larvae collected from the River Tisza were recognized to belong to the genus Parasetodes according to the available generic description. The fact that Parasetodes respersellus is the only European/Western Palaearctic representative of the genus enabled us to describe the hitherto unknown larva of this species based on the collected specimens. Diagnostic features to distinguish the genus from other Central European genera are discussed. Possible species-specific characters are compared with those of other previously described species of the genus. Some notes on larval habitat and the European distribution of P. respersellus are given. Copyright © 2014 Magnolia Press.


Sramko G.,Debrecen University | Gulyas G.,BioAqua Pro Ltd | Attila Molnar A.,Debrecen University
Annales Botanici Fennici | Year: 2011

Convergence in the endangered European bee-orchid species Ophrys kotschyi was studied using a molecular phylogenetic approach. We sequenced the nuclear ribosomal internal transcribed spacer (nrITS) and the Rrn5-TrnR intron of the chloroplast DNA (cpIGS) to resolve conflicting interpretations of its relationships. Some authors include all morphologically similar Greek taxa in the study species, others believe that similarity results from convergent evolution driven by a shared pollinator. Parsimony-based network building and three approaches of phylogenetic tree reconstruction provided a basic insight into the phylogeny of the studied taxa, revealing that the inclusion of the various Greek taxa in O. kotschyi results in a polyphyletic species. This implies the consideration of the species as a narrow endemic to Cyprus, and corroborates the view that convergent evolution is responsible for apparent morphological similarity. Additionally, nrITS sequencing revealed additive polymorphic sites in the nrITS, which implies significant inter-specific gene flow. © Finnish Zoological and Botanical Publishing Board 2011.

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