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This study reports about the collected data from Hungarian section of the River Tisza between 1992 and 2003; data of 24 aquatic snails (Gastropoda) and 13 shellfishes (Bivalvia) were collected from 72 sampling sites. A short demonstration of some species' ecological demand is also given.
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One of the biota that utilizes the mangrove ecosystem as its habitat is a group of Bivalvia belonging to the Phylum Mollusca Class Pelecypoda (Bivalvia). Shellfish have relatively high economic and nutritional value, so that the collection of shellfish in Aceh Jaya District continues. The research was conducted to study the biological components, a...
Citations
... fluminea, D. polymorpha, D. bugensis and T. fluviatilis) can colonize habitats with variable conditions owing to their wider ecological tolerance and special adaptive abilities, whereas threatened species prefer less disturbed habitats because of their narrower ecological tolerance and sensitivity to human activites. Although several of the species recorded are seriously threatened in Europe, only their distributions have been studied thoroughly (Varga and Csányi, 1997;Varga et al., 1998Varga et al., -1999Varga and Uherkovich, 2002;Juhász et al., 2004Juhász et al., , 2009Bódis, 2008;Kovács et al., 2011, Horvai et al., 2012. Indeed, there is a general lack of data concerning basic ecological characteristics such as density, biomass and biotic and abiotic requirements for each species and the Hungarian Danube River Drainage is no exception. ...
Native freshwater mollusc diversity has been declining over the past decades. For developing efficient conservation management plans for molluscs, it is especially important to identify areas with high native biodiversity.
The River Danube is one of the most important freshwater ecosystems in Europe and should receive special attention. The main objective of this work was to characterize the composition, diversity and conservation status of freshwater molluscs occurring in the Hungarian Danube River Drainage in five river habitat types (main channel of the Rivers Danube and Tisza, side channels of River Danube, tributaries of Rivers Danube and Tisza).
In total, 53 mollusc species were identified including 10 invasive species and 12 species of conservation concern. The main determining factors of mollusc composition were sediment characteristics, current velocity and oxygen content. Nitrate–nitrogen, ammonium–nitrogen, and calcium content also play a key role.
Overall, density, species richness and diversity showed significant differences between habitat types. The highest diversity values were detected in the side channels, but the highest proportion of threatened species was observed in the tributaries. The highest number and proportion of invasive species was detected in the main channel of the Danube. Most of the recorded invasive species were previously documented in side channels and the adjacent wetlands, but did not invade the tributaries.
Tributaries may provide refuges for native molluscs and could be considered as ‘source’ populations, which may be critically important in the regional maintenance of threatened species. Tributaries are still less disturbed and less invaded; and should be given priority in future conservation management plans.
Copyright © 2015 John Wiley & Sons, Ltd.
... The Hungarian distribution of Molluscs are relatively well known, faunistical data of freshwater snails from the investigated area are reported by BODA et al. (2012), FARKAS (2005FARKAS ( , 2008, FEHÉR & GUBÁNYI (2001), GLÖER & FEHÉR (2004), JUHÁSZ et al. (2004JUHÁSZ et al. ( , 2006JUHÁSZ et al. ( , 2010, KISS et al. (2006) This paper shows the yet unpublished occurrence data of freshwater Gastropoda arisen from collectings at 175 sites of the WFD-determined waterbodies in Northern Hungary and in the Northern Great Plain between 2005 and 2011. ...
Aquatic macroinvertebrate communities are regularly investigated by the North Hungarian Regional Environmental, Nature Conservation and Water Management Inspectorate since 2005 in Northern Hungary and since 2007 in the Northern Great Plain region as a part of the monitoring program connected to the Hungarian implementation of the European Union's Water Framework Directive. These investigations, due to their regularity and extensive spatial coverage provide valuable faunistical data, few of which have been published up to now. In this paper the faunistical data of freshwater Gastropoda investigations at 175 sampling sites are published that arisen from collectings in Northern Hungary and in the Northern Great Plain between 2005 and 2011. New occurrence data are given for 25 species.
The unionid mussel fauna of the complex system of waterflows, situated on the southern part of the Balaton-catchment was studied. Altogether thirty-seven sampling points on nine watercourses were sampled in order to de-scribe the mussel assemblages of these waters and to as-sess the actual distribution and abundance of chinese pond mussel (Sinanodonta woodiana) populations. Mussels were found in 46% of the localities, in six out of the nine sampled watercourses. Five native and one non-indigenous unionid mussel species were identified during the sampling campaign. The non-indigenous chinese pond mussel was the most fre-quent species, occurred in 13 sampling sites and its relative abundance was 15.5% in the whole sample. our study also revealed that fishponds are potential sources of the invasive S. woodiana in the Balaton-catchment.
Large lowland rivers with sufficient hydrological storage capacity are capable of supporting primary production, but the dynamics
of the advecting phytoplankton is poorly understood. Our study aimed at exploring how longitudinal versus lateral connectivity,
flow dynamics versus resource availability and continuous versus discontinuous environmental gradients shaped the species
composition of phytoplankton. Samples were taken from February to October 2000 along the Hungarian Tisza River (HTR) and in
its main tributaries. Longitudinal and seasonal patterns were related to resources (light and nutrients) availability and
flow dynamics derived from a 1D hydrodynamic model. The HTR was autotrophic during the study period, but tributary input considerably
exceeded net autochtonous production. The Szamos River was the major source of both phytoplankton and nutrients in the HTR.
Chryso- and euglenophytes were flushed into the main river from floodplain oxbows during high discharge. Imported algae experienced
discontinuity in environmental gradients when entering the main river. The merged impact areas of two dams (IAD) that separate
the two large meandering patches of the HTR disrupted the longitudinal profiles of both physico-chemical variables and attributes
of algal assemblages (biomass, species composition, richness, similarity between adjacent sampling sites). Hydraulic storage
along the IAD selectively favoured the recruitment of cryptophytes that, however, could not compensate for the enhanced sedimentation
of diatoms in terms of biomass. Although the meandering patches presented several small-scale differences in major environmental
gradients, both patches supported the growth of planktonic diatoms. Changes in algal biomass were decoupled from nutrient
availability. We conclude that various measures must be applied in various lowland rivers within the same catchment to control
their trophic status as a component of the ‘good ecological status’ defined in the Water Framework Directive.
