| Abstract [eng] |
Investigation of benthic algae communities were carried out in the rivers of different water quality during the period 2004–2006. In total, 61 taxa were identified during this research. They belong to 5 divisions (Cyanobacteria, Rhodophyta, Xantophyta, Bacillariophyta, Chlorophyta), 6 classes (Cyanophyceae, Florideophyceae, Xantophyceae, Bacillariophyceae, Chlorophyceae, Conjugatophyceae) and 17 orders (Chroococcales, Oscillatoriales, Nostocales, Acrochaetiales, Batrachospermales, Hildenbrandiales, Tribonematales, Vaucheriales, Centrales, Pennales, Microsporales, Oedogoniales, Chaetophorales, Ulotrichales, Cladophorales, Tetrasporales, Zygnematales). In the rivers of different water quality the biggest variety of species belongs to cyanobacteria (Cyanobacteria) and green-algae (Chlorophyta). There were detected 25 and 19 species respectively, which accordingly constitutes 41 % and 31.1 % of the whole number of species. The variety of other species were less rich: diatom (Bacillariophyta) - 8 (13.1 %), red-algae (Rhodophyta) - 7 (11.5 %) and yellow-algae (Xantophyta) - 2 (3.3 %). During the study was mentioned that benthic algae distribution are different in the rivers of different water quality (II, III, IV and unknown water quality classes). The cross-rate of taxonomy in those rivers are similar. During the study in the rivers of different water quality the most spread are Chamaesiphon incrustans, Heteroleibleinia kossinskajae, Audouinella chalybea, Vaucheria sessilis, Cocconeis placentula, Achnanthidium minutissimum, Gomphonema truncatum, Aulacoseira islandica, Melosira varians and Cladophora glomerata species. Species which could be spread in all studied rivers haven’t been found. Very rare species are some cyanobacteria (Phormidium ambiguum, Oscillatoria tenuis, Tolypothrix tenuis, Rivularia borealis, Cylindrospermum minutissimum, Nostoc sp.) and red-algae (Audouinella hermanii, Batrachospermum anatinum, Batrachospermum sp.) species. Nine new algae species were found that were not yet detected for Lithuania. One red-algae (Audouinella hermanii) and eight cyanobacteria (Chamaesiphon amethystinus, Hydrococcus rivularis, Heteroleibleinia kossinskajae, Phormidium cliarensis, Phormidium retzii, Phormidium hamelii, Rivularia borealis and Cylindrospermum minutissimum). In the rivers of II water quality classes are spread algae communities: (Akmena (AKM-1)) Cladophora glomerata–Fontinalis antipyretica; (Babrungas (BAB-4)) Amblystegium riparium–Cladophora glomerata; (Babrungas (BAB-5)) Fontinalis antipyretica–Cladophora glomerata. In the rivers of III water quality classes are spread algae communities: (Bražuolė (BRA-4)) Vaucheria sessilis–Phormidium hamelii–Cladophora glomerata; (Bražuolė (BRA-5)) Fontinalis antipyretica–Cladophora glomerata; (Siesartis (SIE-3)) Fontinalis antipyretica–Cladophora glomerata; (Siesartis (SIE-6)) Cladophora glomerata–Potamogeton spp.–Fontinalis antipyretica; (Kulpė (KUL-3)) Cladophora glomerata; (Šeimena (ŠEI-3)) Aulacoseira islandica–Melosira varians–Cladophora glomerata–Stigeoclonium tenue; (Tatula (TAT-2)) Spirogyra sp. (I, II, III, IVa)–Oedogonium sp. (I, II)–Vaucheria sessilis. In the rivers of IV water quality classes are spread algae communities: (Lomena (LOM-4)) Cladophora glomerata–Vaucheria sessilis; (Lomena (LOM-6)) Cladophora glomerata–Potamogeton spp.; (Šalčia (ŠALČ-1)) Aulacoseira islandica–Melosira varians. The variety of the benthic algae species as well as the structure of communities could be determined by several interdependent hydrophysical and hydrochemical factors of environment. These are the variation of heterogenical substratum, velocity of stream flow, the depth of the river, intensity of light and the mane biogenes concentration. Communities more variable in species of algae are formed in those belts of rivers where all previously mentioned factors vary. |
