Daily changes of reed periphyton composition in a shallow Hungarian lake (Lake Velence)

Reed periphyton stucture was investigated int he middle of summer in 1992. Five replicate samples were collected at mid-day over 25 days from living and sterilised reeds. Two weeks before sampling, a 20 cm portion of 150 below water level reed stems were cleaned with brush. After cleaning they were covered with black nylon and aluminium foil. A day before starting the investigation, some substrata were collected as controls and examined under light microscope after preparation. Just before the experimental period the reed stems were placed in a frame. This frame was fixed under the water level to living reeds, at the same sampling point and depth. The number of living and dead cells was counted and chlorophyll-a content of the periphyton was measured. The ratio of dead: live cells was higher in almost all the samples taken from sterilised reed, and was lowest at the beginning of the experiment. The abundance increased continuously over 11 days on both substrata, then there was a slow-increase period („steady state”). The same tendency was observed int he chlorophyll-a content of cleaned green reeds. Changes in relative abundance of some diatoms was also examined during the investigation

Preliminary algological study on biofouling in industrial water systems

This paper deals with the algological investigation and the elimination of biofouling in industrial cooling water systems. Samples were taken from cooling water systems of different Hungarian Works in 1982. The algal fouling of different sampling sites was compared by cluster analysis. We given an outline about the possibilities of protective measures

Preliminary studies on the periphytic algae in the branch-system of the Danube at Cikolasziget (Hungary)

Altogether 179 periphytic algal taxa were identified from the branchsystem of the Danube at Cikolasziget, from different hosts (twig, reed, and other macrophytes). We found that water temperature, shadiness and water discharge affect the composition of the periphyton. According to the species composition of our samples, the number of taxa and the structure of the periphyton show a transitional character between the periphyton of standing and flowing waters

The abundance, taxa richness and diversity of periphytic algae in the Szigetköz region 1991-1995

Quality and quantity of the periphytic algae were investigated before and after the diversion of the main arm of Danube at two big branch-system of Szigetköz. Before the diversion 198 taxa, after it 108 taxa were recorded at Cikolasziget, and 138 taxa before and 96 after the diversion were observed at Ásványráró respectively. While the number of taxa decreased the abundance increased, the diversity decreased at all the sampling points. Floristic changes also were detected

Epiphytic diatoms of the Tisza River, Kisköre reservoir and some oxbows of the Tisza River after the cyanide and heavy metal pollution in 2000

The Tisza River is a large tributary of the Danube River. The largest reservoir of the river is the Kisköre reservoir, and there are furthermore a great number of oxbows in the vicinity of the river. In February and early spring 2000 serious amounts of cyanide and heavy metal pollution were spilled into the Tisza River. The Kisköre Reservoir of the Tisza was less polluted than the river itself. However, the four oxbows investigated were flooded by the Tisza River in April 2000. Epiphytic diatom samples were taken in February and October 2000 along the Tisza River, in November and December 2000 at the Kisköre Reservoir and in May and July 1996, October 2000 and June 2001 at the four Tisza oxbows. The aims of this study were to obtain preliminary data about the species composition of the attached diatoms of these waters, to evaluate the impact of the pollution on epiphytic diatoms and to evaluate the natural protection value of these waters. Epiphyton of the Tisza River was dominated by Achnanthidium minutissimum, Amphora pediculus, Cocconeis placentula, Diatoma moniliformis in February and by Achnanthidium minutissimum and several Nitzschia spp. in October. A number of teratological frustules were observed. In the Kisköre reservoir, Amphora pediculus, Cocconeis pediculus, C. placentula, Cyclotella meneghiniana, Gomphonema angustum, Nitzschia dissipata were dominant. In 1996 Staurosira, Staurosirella and Navicula species dominated in the oxbows, whereas in 2000 Aulacoseira distans, Achanthidium minutissimum and Nitzschia spp. became dominant. Based on results from the literature, we are of the opinion that the characteristic Achnanthidium minutissimum - Nitzschia spp. dominance of the Tisza River and the oxbows is partly due to the heavy metal pollution. A number of endangered species, two new elements for the Hungarian diatom flora - Navicula austrocollegarum and Navicula streckerae - and two probably invasive species, Diadesmis confervacea and Didymosphenia geminata were found

Changes in the algal composition, bacterial metabolic activity and element content of biofilms developed on artificial substrata in the early phase of colonization

Changes in the algal composition and metabolic profiles of bacterial communities as well as the inorganic components were studied on artificial substrata during the early phase of biofilm formation under laboratory conditions in September 2002 and 2003. Sterile Perspex and polished quartz glass discs with a diameter of 3 cm were placed into a Perspex rack, which was immersed vertically in an aquarium containing water from a shallow soda lake. The temperature was kept constant and sufficient oxygen supply was provided. The samples were illuminated for 12 hours a day. Periphyton communities were sampled from 2 to 126 hours of exposure. In both experiments, the alteration of the number of algal species and cells as well as the carbon source utilization of microbial communities was logarithmic. In the two years, considerable differences were revealed in the magnitude of algal cell numbers. The proportion of benthic and planktonic algae showed an undulating pattern in the second experiment. One of the dominant benthic species was the diatom Achnanthidium minutissimum Kütz., while that of the planktonic, the cyanobacterium Microcystis aeruginosa Kütz. During the experiments an increase in the bacterial activities could be observed; the higher the microbial diversity and abundance that was detected, the more BIOLOG carbon sources were utilized. The examined element contents indicated interactions among algae and bacteria in the biofilms from the beginning of the colonization processes

Silica scaled Chrysophytes during spring in the Kis-Balaton reservoir, Hungary

As a result of taking water samples in spring 1999, 26 species of silica-scaled chrysophytes were found in the Kis-Balaton Reservoir I, one of the most remarkable aquatic habitats in Hungary. From them, 23 have been identified with certanity, two were questionable and two were identified to genus level. 12 species are new to Hungary and 19 species had not been found in Kis-Balaton before. Most of the species are widely distributed, occuring mainly in eutrophic waters. The most abundant species were Paraphysomonas vestita, Synura petersenii and Mallomonas alpina, all three widely distributed, cosmopolitan species. Beside these, Mallomonas cratis and Mallomonas acaroides were found to be common members of the vernal flora of silica-scaled chrysophytes in Kis-Balaton. Mallomonas pseudocratis has been found only in a few places in the world, while Mallomonas alata and Mallomonas parvula have bipolar distribution

Changes in the mosaic-like water surfaces of the Lake Velence as reflected by reed periphyton studies

Long term changes of the reed cover of the Lake Velence (12 years) were summarised for this paper, with emphasis on the results of investigations in 1989 and 1990. Ont he basis of the analyses it appeared that the water surface of the lake had lost its former mosaic-like character, which was primarily caused by intensive reed harvesting. Due to the scarcity of water since 1989, the salinity of the lake was increasing, as indicated by the increasing relative abundance of Chaetoceros muelleri as well as other factors. Scarcity of water also explains that algal fields detached from the basement are getting wide-spread even in protected areas (still preserving the water quality characteristic of the dark brown water surfaces), especially species of filamentours blue algae

Magyarország Centrales fajainak florisztikai felmérése összefüggésben a természetvédelemmel = Floristical studies on centric diatoms in Hungary concerning the nature conservation

A pályázat során Magyarország keleti területén közel 200 álló- és folyóvízből több mint 300 mintát vizsgáltunk, valamint vízkémiai változókat is mértünk mind a helyszínen, mind a laboratóriumban. A mintákat pásztázó elektronmikroszkóppal vizsgáltuk. Minden fajról elterjedési térképet is készítettünk. 41 Centrales taxont találtunk. Legfajgazdagabb a Duna volt, legfajszegényebbek a kis vizek. A taxonómiai és elterjedési vizsgálatokon túlmenően adataink számos ökológiai aspektusú elemzésre is lehetőséget nyújtottak. A taxonszám összefüggést mutatott a folyók méretével, mivel a beömlő mellékfolyók, ill. a velük kapcsolatban lévő tavak, tározók fajai is a befogadó folyóvíz fitoplanktonját gazdagítják. Nem véletlen, hogy Magyarország legnagyobb folyója a Duna Centrales közössége a legfajgazdagabb, hiszen hatalmas terület vizei kapcsolódnak hozzá és a tavi környezetre jellemző fajok a Duna lassan áramló vizében sokáig túlélnek, közülük számos szaporodni is képes benne. Állóvizek esetében a fajtelítési görbék azt mutatták, hogy a növényi tápanyagban gazdag halastavak a legfajgazdagabbak és a nagy vezetőképességű szikesek a legfajszegényebbek. A kutatás lehetőséget teremtett arra, hogy néhány taxon esetében részletes morfológiai vizsgálatot végezzünk és tisztázzuk taxonómiai helyzetüket is. | In the framework of the project 300 samples were investigated from 200 stagnant and fluvial water bodies in the eastern part of Hungary. Water chemical parameters were also measured on site, and in the laboratory. Samples were investigated by scanning electronmicroscopy. Occurrence maps were constructed for each species. Altogether 41 Centrales species were detected. The highest species number was found in the River Danube, while the lowest ones in small water bodies. Besides taxonomical and occurrence investigations, the data could be used for different other ecological analyses. The taxon number correlated with the size of the rivers, as the tributaries, and the connected lakes and reservoirs increase further the species richness of the receptive rivers. This explains the highest species richness of the largest Hungarian river, the River Danube. It has a huge catchment area with several tributaries, and standing water species survive for a long time in the slowly flowing river, many of them find favourable conditions even for reproduction. In standing waters, species accumulation curves revealed that nutrient rich fish ponds are the richest in species, and high conductivity soda lakes are the poorest. As a part of the research detailed morphological investigations could be performed in some species to understand and clarify their taxonomic position