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Cadmium and lead accumulation in two littoral plants of five lakes in Poznan, Poland

100%

Drzewiecka K. , Borowiak K. , Mleczek M. , Zawada I. , Golinski P.

nr 2

We measured cadmium and lead concentrations in two littoral plants (Phragmites australis Cav. Trin ex. Steudel and Typha angustifolia L.) collected in June and September 2007 from five selected lakes in the Poznan city area, and also in sediment and water samples from the same places. We determined the metal concentrations in rhizomes and leaves, and in sediment and water from the littoral and near the bank zone. Only low levels of the heavy metals were found. Pb and Cd concentrations were higher in water collected from the bank zone than from the littoral zone. Pb and Cd accumulation was noted in sediments. Heavy metal levels were higher in rhizomes than in stems and leaves. The studied aquatic macrophytes may be bioaccumulators and bioindicators of Pb and Cd in freshwater in natural conditions, even when concentrations are low.

Rośliny wody płytkiej

100%

Marosz A.

nr 05

Periphytic algal communities: a comparison of Typha angustifolia L. and Chara tomentosa L. beds in three shallow lakes [West Poland]

100%

Messyasz B. , Kuczynska-Kippen N.

nr 1

The examination of the composition and dynamics of periphytic communities took place in three lakes of similar morphometry – Lake Wielkowiejskie, Budzyńskie and Dębiniec, situated in the Wielkopolska region, (Western Poland). These lakes are typical macrophytedominated, shallow and polymictic water bodies. Periphyton was collected from two macrophytecovered stations, including the rush vegetation station (Typha angustifolia L.) and the stonewort stand (Chara tomentosa L.) in each examined lake. The material was sampled three times in 2003, including the spring (April), summer (July) and autumn (September) seasons, from the same parts of the lakes. The aim of the study was to find out whether there is an influence of particular macrophyte species, differing spatially and morphologically and representing two different ecological types of aquatic vegetation, on the development of particular periphytic species. There was also an attempt at answering the question of what is more important in the structuring of the periphytic communities – the specific architecture of the macrophyte substratum or the physical-chemical features of a particular lake? The concentrations of chlorophyll a, TN, TP and TOC in water were higher in the Chara beds compared with the Typha stations in most cases. The Shannon-Weaver biodiversity index of periphytic algae revealed very high values in all lakes and amounted in the Typha and Chara stands to the mean values 4.68 and 3.87 respectively in Wielkowiejskie Lake, 3.32 and 4.39 in Budzyńskie Lake and 3.08 and 3.91 in Dębiniec Lake. Furthermore, the standardized index of evenness exhibited the greatest differentiation in the Typha station with the highest (0.76) in Wielkowiejskie and the lowest (0.52) in Dębiniec Lake. The analysis of the growth-forms of periphytic communities showed slightly higher diversity of slowly moving and stalked diatoms in most cases at the Chara stations of all studied lakes. The similarity between periphytic communities in the Typha and Chara stands of the examined lakes, compared using the Ward method and Euclidean distance measure, revealed a stronger relationship within a particular habitat but not a lake. The clearest pattern of similarity grouping a particular habitat was obtained for the summer period, when macrophytes reached their optimum. The Jaccard similarity index confirmed the differentiation of both examined habitats, reaching the mean value of 0.34. Based on the biomass of single periphytic species, habitat selectivity for seven species was found. Significantly higher biomass was obtained in the case of the rush zone for only one algae species – Eunotia lunaris (Ehr.) Grun. In the Chara bed six species revealed significantly higher biomasses – Cosmarium regnelli Wille, Oocystis marssonii Lemm., Ulotrix zonata (Weber et Moor) Kütz., Scenedesmus acuminatus (Lagerh.) Chod., Merismopedia elegans A. Braun and Phacus orbicularis Hübner. The habitat preference of periphytic communities to different macrophyte species may be due to the environmental factors, including the specific architecture of a particular macrophyte substrate such as density or texture of the plant surface. Furthermore, seasonality, as well as physical-chemical parameters may structure periphytic communities within the littoral zone of lakes.