In the years 2009-2010 limnological research was carried out on 13 lobelia lakes of the Tricity metropolitan area. These lakes, of unique value not only on the scale of the country, are undergoing degradation due to increasing anthropogenic pressure. Grade of degradation of these lakes, depends on geoecosystem type, which they are representing. Geoecosystem type of the lake, defines the rate of natural eutrophication of reservoir. In this article types of geoecosystems of analysed lobelia lakes where defined in accordance with the guidelines of Bajkiewicz-Grabowska (1981, 1983, 1987, 2002. The obtained results indicate that only one of the analysed lakes (Zawiat Lake) is likely to retain a low trophic level. Four lakes (Głębokie, Kamień, Borowo, Techlinko) represent geoecosystems with a moderate rate of natural eutrophication. The remaining of the analysed lobelia lakes are threatened with fast water eutrophication, which is demonstrated by a high catchment vulnerability to activate areal load, and a low resistance of the lakes (resulting from their natural properties) to external supply. The obtained results correspond to field measurements and make it possible to indicate actions aimed at protecting the group of the analysed lobelia lakes.

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Application of geoinformation techniques to determine zones of sediment resuspension induced by wind... Limnol. Rev. (2016) 16, 1: 3-14 DOI 10.2478/limre-2016 IntroductionWhen deciding which method to use for restoring a lake ecosystem to good ecological status, environmental pressures (natural and anthropogenic) on that ecosystem must first of all be assessed (Bajkiewicz-Grabowska 1981, 1983, 1985, 2002, 2010 and, based on this assessment, the sources responsible for the ecosystem's status are identified. These are mainly external sources, i.e. the area of land providing influx of water and biogenic matter to the lake (the lake's catchment) together with the lake users (humans and birds), although sources responsible for the so-called internal loading (e.g. Boström et al. 1982;Wiśniewski 1995;Kajak 1998) can also significantly contribute to the lake's trophic state and ecological condition (e.g. Bajkiewicz-Grabowska 2015). The magnitude of the lake's internal loading depends on the amount of organic matter deposited in lake-bed sediment and nutrient content. Products of decomposition of this organic matter can re-enter the circulation in the lake (e.g. by resuspension) as secondary loads and markedly accelerate the process of eutrophication (e.g. Wiśniewski 1995; Van Hullebusch et al. 2003;Watts 2000). Multiple cases of deterioration in lake water quality caused by sediment resuspension have been reported (Bengtsson and Hellström 1992;Kristensen et al. 1992;Søndergaard et al. 1992;James and Barko 1994;Ekholm et al. 1997;De Vicente et al. 2006).Resuspension of lake-bed sediment may be driven by wind-induced waves (or wind waves) (Ward 1980;Leuttich et al. 1990;Bachmann et al. 2000;Douglas and Rippey 2000).Based on studies that differed in terms of morphometry, water dynamics and trophic state, it has been concluded that wind-induced resuspension of sediment plays an important role in the oxygen balance of shallow lakes and the littoral zones of deep lakes (e.g. Wiśniewski 1995). Wind waves propagated to the shear stress zone along the bottom of the lake set in motion water currents sufficient to resuspend fine lake-bed sediments and interstitial waters which could result in significant amounts of phosphorus being loaded to the overlying waters.The modelling of the impact of wind waves on resuspension of lake-bed sediment has long been a well-known topic in the literature. A significant conApplication of geoinformation techniques to determine zones of sediment resuspension induced by wind waves in lakes (using two lakes from Northern Poland as examples)Elżbieta Bajkiewicz-Grabowska, Maciej Markowski, Krzysztof LemańczykDepartment of Limnology, University of Gdańsk, Bażyńskiego 4, 80-952 Gdańsk, Poland, e-mail: bajka37@wp.pl; geomma@ug.edu.pl (corresponding author); krzychu@lemanczyk.com Abstract: Resuspension in lakes affects the quality of lake water. It is possible to model this process and visualize its outcomes using GIS tools. An assessment of the size of the zone of sediment resuspension was made for two...