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The succession of periphyton developing on artificial substrate immersed in a polysaprobic wastewater reservoir was studied during a two-year period. Three stages in the periphyton development: initial, inter­mediate and mature, were observed. The initial stage was characterized by domination of euglenophytes; Carchesium polypinum was dominant during the intermediate stage, while diatoms and chrysophyceans dominated the mature stage. However, the most characteristic component of periphyton consisted of de­tritus that contributed more than 50% (by volume). The periphyton development dynamics in the second year of the experiment, when that formation was already firmly established on the polyethylene sheets, was quantitatively similar to the process of periphyton development in the first year of substrate exposure.
Studies on parasitism in zooplankton and periphyton assemblages were carried out on samples of water collected from Lakes Płociczno and Płociowe in the Drawa National Park in 2008-2011. Occurrence of the fungal mycobiotal and protozoan parasites of invertebrates was recorded in both lakes. Parasitism of Chydorus sp. (Cladocera) by Saprolegnia sp. occurred on 0.8% of individuals of the host population, of Brachionus calyciflorus (Rotifera) by Microsporidium sp. on 1.2% of the host population, and of Nematoda members by Pythium sp. on 5% of the host population. Parasites were recorded only in springtime.
Analyses of three macroelements and six microelements in reed stems, accompanied by investigation of periphyton density were carried out in two reservoirs: Żarnowieckie Lake and Puck Bay. To reveal the influence of chemical composition of biotic substrate on periphyton qualitative and quantitative characteristics, ordination methods were applied (PCA, CCA, DCA, RDA). The results indicated that Copoepoda (Harpacticoida) and Chlorophyta preferred reed substrate with relatively high zinc, sulfur and chromium but low manganese and carbon content. In turn, Nematoda reached the highest density on a substrate rich in manganese. Mercury in reed limited density of Arachnidae-Hydrachnella and Chironomidae larvae, an effect which was not observed for Ciliata libera. Copepoda (Harpacticoida) preferred low chromium and lead content and high carbon/nitrogen ratio, which meant low nitrogen concentration in the reed substrate. Moreover, preferences of Nematoda and Bacillariophyta for freshwaters and Copepoda for brackish waters were indicated. The results presented in this paper should be treated as a contribution to more detailed research on interactions between reed chemical composition and periphyton density.
Polythene sheets deployed in Lake Miewie (area 3500 ha) were chiefly colonized by the zebra mussel, Dreissena polymorpha Pall. They were also used as substratum by freshwater triclads, oligochaetes, leeches, and snails for attaching eggs, and as spawning ground by fish. On the other hand, the development of algae on them was very poor. The sheets survived undamaged a year in the littoral zone of the lake characterized by very strong waves and horizontal currents.
The presence of riparian vegetation is shown to affect both physical and biological properties of headwater streams. Riparian vegetation mediates food resource availability for macroinvertebrates and fish within streams through addition of allochthonous material such as leaves, woody debris and terrestrial invertebrates. Riparian shade can also reduce biomass and production of autochthonous algae. The potential role of riparian vegetation in enhancing biodiversity and productivity of headwater streams is discussed, with reference to improving salmonid fish stocks in the headwater streams of Ireland and Great Britain.
Periphyton colonisation on artificial substrate (microscopic glass slides) was investigated from July to November 2007, in Lake Sakadaš (Danube River floodplain Kopački rit, Croatia). Two different stations were chosen due to different post – flood conditions. The aim of the study was to follow temporal changes of nematode community composition and trophic structure in relation to periphyton biomass and bacterial abundance. In bryozoan – dominated periphyton (Plumatella emarginata Allman, 1844) nematodes were represented by 86 and 87% of total associated invertebrate fauna at S1 and S2 respectively. Total nematode abundance (up to 600 ind. 10 cm-2 at one station and up to 1130 ind. 10 cm-2 at another station) correlated significantly with the abundance (meaured as CFUs – colony forming units) of copiotrophic and oligotrophic bacteria at one station (r = 0.963, 0.998, P <0.05) and with organic and inorganic content of periphyton at another station (r = 0.891, 0.899, P <0.05). Nematode trophic groups (epistrate feeders, chewers, detritus feeders and suction feeders) were equally developed at both stations except detritus feeders whose species richness and abundance were significantly higher at the S1. Epistrate feeders were the most abundant trophic group in nematode assemblages at both stations with Chromadorina bioculata being the dominant species. Change in dominance of epistrate feeders by chewers (Brevitobrilus stefanskii) and suction feeders (Crocodorylaimus sp.) coincided with the occurrence of flood pulse. Effect of flood pulse on nematode community structure was probably indirect, alterating concentration of dissolved oxygen which chromadorids are sensitive to. The structure of nematode community developed through time differs between investigated stations indicating high sensitivity to bacterial abundance, periphyton biomass and P. emarginata mats which made the habitat more diverse and patchy.
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