Investigated Water Bodies Research Articles

Variability of phycobiliproteins in cyanobacteria detected by delayed fluorescence excitation spectroscopy and its relevance for determination of phytoplankton composition of natural water samples

Delayed fluorescence (DF) excitation spectroscopy is a fast in vivo method to determine phytoplankton composition in freshwaters using the signature of photosynthetically active pigments which is characteristic in each algal class. Four classes could be distinguished: green algae (including Chlorophyceae, Euglenophyceae and Conjugatophyceae), chromophyte algae (including Bacillariophyceae, Chrysophyceae and Dinophyta), Cryptophyta and cyanobacteria. The DF excitation spectra of various cyanobacteria species were investigated with the aim of improving the reliability of the results obtained by DF. Exposing cyanobacteria to different ambient light conditions did not significantly influence the shape of DF excitation spectra. However, the DF excitation spectra of different cyanobacteria species showed different signatures: a high species-specific variability of the ratio phycocyanin (PC):phycoerithrin (PE):allophycocyanin (APC) derived from DF excitation spectra was observed. This variability has to be taken into account when using DF to determine phytoplankton composition in freshwaters dominated by cyanobacteria. The quality of the fits could be significantly improved by using calibration spectra of cyanobacteria species which are, according to their spectral features, at least similar to those species present in the investigated water body.

Influence of water level fluctuation on the spatial dynamic of the water chemistry at Lake Fertõ/Neusiedler See

Lake Fertõ/Neusiedler See is a steppe lake situated on the Hungarian-Austrian border with a surface area of 309 km 2. It is an extremely shallow lake with regulated outflow. 54% of the whole lake and 85% of the Hungarian part (75 km 2) is covered by reed. There are numerous reedless areas (inner ponds) of variable size within the reed belt, which is enmeshed with canals connecting the inner ponds with the open water areas. Fundamental differences were recorded in the water chemistry of the three water type areas, open water, canals and inner ponds. The degree of these differences is basically determined by the distance from the open water areas and the water level of the actual years. An extremely high, an average and an extremely low water level year was examined, in order to present the spatial and temporal differences in the water chemistry of the investigated water bodies. Differences due to the water level fluctuation between years in the three different water types are discussed on the basis of electrical conductivity, cation, and anion concentration changes of the water. Our results support the concept of high instability of Lake Fertõ and describe habitats with remarkable temporal and spatial variability. The high influence of water level on habitat conditions at different sites of the lake recommend a carefull water level regulation strategy.

Comparison of feeding spectra of some exotic and native fishes in Vojvodina (Serbia)

Given the role of algae as primary producers and the possibility of reduction in their numbers by some fish species, as well as possible food competition between some autochthonous and allo‐chthonous fishes which are consumers of algae, feeding of two autochthonous species (carp and roach) and two allochthonous species (crucian carp and bighead carp) was investigated. Investigations were carried out in the following aquatic ecosystems: Sta‐ri Begej, Palicko Jezero and Bukinski Rit which are parts of the legally protected areas (nature reserves). All investigated aquatic ecosystems are eutrophic ones, characterized by high density of phytoplankton communities in which Bacillariohyta and Chlorophyta are the dominant algal groups. Feeding spectra preliminary investigation showed that algae take an important place in feeding of investigated fish species. Analyses of the algal component showed that participation of the different algal groups varied, but, generally, Bacillariophyta and Chlorophyta were dominant, which correspond to their domination in the waters. Detailed analyses of the algal component showed that, concerning the contribution of algal groups, there were no significant differences between the investigated fish species. It suggests likely possibility for food competition, as well as that some autochthonous species, such as the carp and roach, can decrease the density of algae as successful as the allochthonous ones, such as the crucian carp and bighead carp. Given that all of the investigated water bodies are the parts of protected areas characterized by a high diversity of autochthonous species, and that the allochthonous species can be a real threat to them, it is necessary to carry out measures directed to reducing the numbers or eliminating the allochthonous species from the protected water bodies.

Input of ionic alkyllead compounds to surface waters

Concentrations of ionic alkyllead compounds (IAL) and the total lead in different types of water from continental (the town of Zagreb) and coastal (the town of Šibenik) parts of Croatia have been measured. The ranges of IAL concentrations obtained were: in untreated urban wastewater 7.5–27.5 ng Pb/1(0.01–0.05% of Pb TOT), in river water < 0.5–7.5 ng Pb/1 (0.01–0.9% of Pb TOT), in lake water 0.4–2.4 ng Pb/1 (0.1–2% of Pb TOT) and in seawater < 0.5–12.5 ng Pb/1 (0.6–6.8% of Pb TOT). The manner of transport of lead compounds to various surface waters is discussed. The main sources of organic lead for the investigated water bodies were as follows: for river water — untreated wastewaters, for a small lake — wet deposition and for the coastal sea — the gasoline station. Concentrations obtained were in good agreement with literature data on the organolead level in surface waters from Europe.

Multi-channel laser doppler velocimetry (LDV) and digital image processing (DIP) in fluvial hydromechanics

Recent efforts in fluvial hydromechanics aim at the capability of reliably predicting fluvial flow, turbulence and mass transport by means of multi-dimensional hydrodynamic numerical models. For this purpose, most detailed and highly accurate experimental data are needed in order to calibrate and verify the simulation tools. An optimum, but so far non-existing measurement technique would provide the complete state-space representation of the investigated water body at a high spatial and temporal resolution. While this is far from being available, already well established optical methods, such as Laser Doppler Velocimetry (LDV) and Digital Image Processing (DIP), seem to bear the potential for coming close to the optimum if applied in effective combination. Within this paper, several corresponding applications of LDV and DIP to the investigation of compound open-channel flow are described and discussed regarding their characteristic results, advantages and disadvantages as well as possible future improvements.

Water mollusc communities and bioindication of lower salzach floodplain waters

AbstractThe lower Salzach River lost its natural river dynamics as a result of channelization, which caused its bed to deepen, its groundwater table to be lowered, and its floodplains to gradually dry out. These changes of the floodplain have lead to a loss of natural biotopes with their biocoenoses. By using water mollusc communities as bioindicators these losses are detectable at a landscape level. A numerical analysis of a water mollusc survey in 1989 defined six water mollusc communities identifying six water‐body types: three flowing (streams, ditches, and rivers) and three standing (young former meanders, large deep groundwater‐influenced backwaters and small shallow groundwater‐influenced backwaters) within the lower Salzach valley. These communities and water‐body types are interpreted using results from water mollusc communities of other floodplain systems and by comparison with earlier water mollusc surveys in the lower Salzach valley. Then predictions are made on the future fate of the investigated floodplain water. Finally the investigated water bodies are evaluated for nature conservation in the face of plans to impound the lower Salzach River.