A new floristical survey of the algal flora of the Babat valley, Hungary

During a recent algological survey, carried out in 2001 at 6 small ponds of the Babat valley near Gödöllő, central Hungary, 209 taxa were recorded, of which 122 are new records. Two of the ponds (Nos 10–11) are semi-natural, in these we identified 65 and 91 algae, respectively. Adjacent to the shore of two other ponds (Nos 8–9) goose breeding is going on, with 56 and 41 taxa recorded in these manure-polluted ponds. The polluted water from these ponds runs directly to two further (lower) ponds, with 85 and 66 taxa identified, respectively. Several diatoms appear to be new for the flora of the Babat farm, which is attributed to the methodological differences between an earlier study and the recent survey. Surprisingly, Cylindrospermopsis raciborskii, the very common, toxic cyanobacteria, was found only in one, semi-natural pond having a unique, diverse alga flora. Chara canescens was found in the upper pond in the spring

Diadesmis brekkaensoides (BOCK) GERD MOSER, LANGE-BERTALOT et METZELTIN: a new aerophytic diatom for the Hungarian flora

Diadesmis brekkaensoides (W. Bock) Moser, Lange-Bertalot et Metzeltin, a very rare aerophytic diatom was found in the Kiskőhát shaft in the Bükk Mts. A dense population of algae, perfectly corresponding with the original description of Bockin 1963, was found on a wet rockin the deep shadow. So far, the author could not find more than two other reports of this species; the first one from the Alps, the second one from New Caledonia

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

Contribution to the knowledge of Algal flora of the Aggtelek National Park

Containing all published data from surface and underground habitats of the Aggtelek National Park, with additions based on the algological collection of the Hungarian Natural History Museum, a total of 292 Cyanobacteria and algae taxa (437 records) are listed as the first comprehensive account of the Cyanobacteria and the algal flora of the area

Paleolimnological evidences for the rise and fall of a star-like planktonic diatom (Asterionella formosa) during the Anthropocene = Paleolimnológiai adatok egy csillagszerű, planktonikus kovaalga, az Asterionella formosa „tündökléséről és bukásáról” az Antropocénban

Asterionella formosa is known as a common and often dominant planktonic diatom in mesotrophic and eutrophic lakes worldwide. The bone-shaped Asterionella cells often form colonies consisting usually of eight cells, but the number of cells can reach up to 20 cells. The colonies are star shaped, and this shape slowing down settling velocity can makes them dominant in low viscosity warm water. Recently the abundance of this species increases in oligotrophic lakes as well. It is a rather well established fact, that the proliferation of A. formosa correlates with nutrient enrichment, especially when atmospheric nitrogen deposition intensifies in the lakes. However, there are increasing numbers of paleolimnological evidence, that other factor may be responsible for the spreading of this diatom. High-resolution, multi-proxy study was carried out on a sedimentary record obtained from Lake Ighiel (46°10’50"N, 23°22’00"E). Lake Ighiel is located in Alba County, Romania, in the south-eastern part of the Trascaului Mountains in the Romanian Carpathians. This small lake is located in a mid-altitude mountain belt at 924 m above sea level, with a maximum depth of 9 m and a catchment area of 487 hectare. The here presented results are focussing on the increase and decrease of A. formosa abundance. Lake Ighiel was formed ca. 6000 years ago, however the siliceous algae were able to preserve in the sediment from ca. 4800 cal yr BP. After the dominance of small fragilaroids, the Middle Holocene (ca 4800– 4200 cal yr BP) is marked clearly by a relative increase in benthic Navicula and Gyrosigma taxa, indicating habitat diversification. There is an episodic return to small fragilaroids from 2600 to 2500 cal yr BP with some periphitic taxa becoming abundant. In the last 1000 years A. formosa increases in relative abundance, reaching dominance in the last 200 years, while before it had been only sporadic in the sedimentary record. We can assume a strong positive correlation between the abundance of A. formosa and global warming. Probably development of soil also influences contribution of this species to the diatom assemblage. The period of the II. World War is imprinted as a decline of A. formosa in the assemblage. Global warming related changes, like longer open water periods, changing mixing regimes and thermal properties of water might have contributed to the increased abundance of A. formosa. In the last couple of years the „star” of Asterionella dramatically and abruptly fell, while the small celled Centrales taxa practically replaced it in the lake sediment. To disentangle if nutrient supply and/or climate are main driving force on diatom distribution is an unsolved problem. The authors acknowledge financial support from OTKA 119208, CRYPTIC project

Nem planktonikus diatómák koegzisztenciális struktúrái = Coexistential structures of non-planktonic diatoms

A kutatási programban meghatározott célunknak megfelelően összehasonlító vizsgálatokat végeztünk mohákon, algagyepekben valamint békalencséken élő diatómavegetáción. Egy, a tudományra új, 6 a magyar flórára új diatomafaj került publikálásra. A román flórára 25 új diatómát találtunk. 18 ritka, potenciálisan veszélyeztett diatóma előfordulásáról publikáltunk adatokat 11 magyarországi lápról. A Lemnicola hungarica különböző békalencsefajokhoz való kötődését vizsgáltuk hazai gyűjtésekben és európai exsiccata anyagokon. Az acidofil-acidobionta diatómák tanulmányozása számos új eredménnyel szolgált, ami elvezetett a Szent Anna tó palaeolimnológiai feldolgozásához. Munkánkról 5 nemzetközi és 3 hazai konferencián számoltunk be, valamint 7 angol nyelvű és 1 magyar nyelvű cikkben ismertettük eredményeinket eddig. | In accordance with the primary aims defined in the research plan we carried out comparative examinations on bryphytic, metaphytic and Lemnaceae-inhabiting diatom vegetation. One new diatom species description was published and 25 new diatom taxa were found in Transsylvania and these are novums for the flora of Rumania. 6 new floristic data were published for the Hungarian flora. In the 11 studied Hungarian mires the occurrances of 18 rare, and potentially threatened diatoms were published. The coexistence of Lemnicola hungarica with various taxa of Lemnaceae were studied in Hungarian samples as well as European exsiccata material. The study of acidophilous-acidobiontic diatoms revealed new results, which provided basis for the palaeolimnological reconstruction of Lake Saint Ana. As an outcome of this project the results were presented in various forms and occasions including 5 international and 3 Hungarian conferences, and to date 7 papers in English and 1 in Hungarian have been prepared

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

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