Sengupta, M. and Dalwani, R. (Editors). 2008 Proceedings of Taal 2007: The 12th World Lake Conference: 2254-2257
The Effect of Submerged Macrophytes on Water Trophy Formation in Lakes and the Great Water Bodies of the Wielkopolska Region (Western Poland) T. Joniak* and N. Kuczyńska-Kippen Department of Water Protection, Faculty of Biology, Adam Mickiewicz University of Poznań Umultowska 89, 61-614 Poznań, Poland, *Corresponding author: Email:
[email protected] ABSTRACT The estimation of the trophic conditions of waters in the vegetated zone and the open water zone of shallow water bodies (in western Poland) based on the analysis of their chemical parameters according to Carlson's Trophic State Index was the aim of the study. The physico-chemical parameters of water were examined in the summer season on 6 shallow lakes and ponds. In the studied water bodies 7 aquatic macrophyte habitats were distinguished from rush the vegetation and submerged macrophytes. The differentiation in the trophy of water bodies was small. In the course of the analysis a number of limitations of the applied classification methods for ascertaining the trophic conditions were found. In zones of submerged macrophytes a distinctively higher concentration of phosphorus and chlorophyll a was found, which indicated that the water trophy of those habitats was wore when compared to the zones of helophytes. The specific problems encountered during the examination were the small depth of water bodies, which often corresponded with the depth of the SDV. Keywords: trophy, small water bodies, hydromacrophyte, eutrophication, SDV
INTRODUCTION The trophic conditions of water are often decisive when taking into consideration the potential usage of water bodies. In relation to submerged macrophytes, opinions considering the role of macrophytes in modifying the physical-chemical features of the environment of water bodies have as yet not been defined. On one hand the dynamics of water in shallow lakes is often determined by irregular processes e.g. wind mixing (Joniak et al. 2000), and on the other hand overgrowing macrophytes may intake nutrients from water or restore them from sediments into the water (Kajak 2001). According to the most recent literature mainly nitrogen compounds, which are included in artificial fertilizers, which are the major factor responsible for accelerating the eutrophication of surface waters (Bubier et al. 2007). This influences the quality of inland waters which are endangered by the increase of trophic conditions as a result of enrichment from the catchment area. From the hydrological point of view water bodies play an important role, e.g. they contribute to moisturizing soils, however, their overeutrophication degrades their waters almost to the point of sewage conditions. In the estimation of the quality of surface waters many classification systems are used e.g. Carlson (1977) in which classic trophic terminology relates to numerical values of chosen parameters. The aim of the study was to determine the differentiation of value of the Carlson trophy index in the macrophyte zone (rush vegetation, submerged macrophytes) in
comparison to open water zone of three lakes and three great water bodies of the Wielkopolska region (western Poland). STUDY AREA, MATERIALS AND METHODS In the Wielkopolska region due to the frequency of land melioration, water supplies are among the most restricted in Poland. The systematic decrease in surface and ground water levels is a direct result of the drainage works that were conducted intensively in the XVIII, and especially in the XIX century. By this time Wielkopolska had already turned from a well irrigated land, rich in running waters and old river beds into an area which was beginning to dry out (Czubiński 1947). In such circumstances help for dry agricultural soils could be found in bogs and marshes, including small water bodies. A serious threat to the Wielkopolska surface waters lies in the continental climatic conditions, and in particular certain features such as severe winters, hot summers and low fall rates in the transitional climatic seasons. The examination of the chemical parameters of water were carried out in the summer of 2005 on 3 lakes (surface area from 11 to 15 ha, max. depth 2.77.4 m-1) located in forest and pastoral/forest catchment and 3 typically mid-forest ponds (surface area < 5 ha, max. depth
