Estimation methodology and the significance of the atmospheric water exchange flux in the river-lake systems of selected lobelia lakes in the vicinity of the Tri-City in Poland

The article aims to present the methodology of estimating the atmospheric water exchange components in the lake. In the absence of direct precipitation and evaporation measurements, these water balance elements need to be estimated. However, the inadequate selection of precipitation and evaporation estimation methods causes the incorrect determination of the hydrological function of the lake and the effect it has on the formation of river drainage. Determination of the evaporation from the lake’s surface was based on the Davidov formula, which considered the monthly average surface temperature of a given lake. The saturated water vapour pressure under the lake’s monthly mean surface water temperature (TWP) was calculated according to ISO 13788 standard. The interpolation method, which is the inverse-distance deterministic method (IDW), was used to calculate precipitation reaching the lake surface. The calculations were made for three hydrological years diverse in terms of humidity and thermal conditions. The methodology for estimating the components of atmospheric water exchange was presented on a small river-lake system of the upper Gościcina River catchment, an example of a postglacial lake district area. The lake elements of this system are lobelia lakes, poorly known in terms of water circulation. At the beginning of the twenty-first century, unjustified activities regarding assessing the water circulation conditions in this river-lake system led to changes in water relations, causing environmental, financial and social losses.

The Variability of Lake Water Chemistry in the Bory Tucholskie National Park (Northern Poland)

The paper presents the results of chemical analysis of lake waters in Bory Tucholskie National Park (BTNP). The BTNP area is unique due to its location within a single catchment and high variability in geological structure. Moreover, the lakes have different morphometric parameters, represent different hydrological types, trophic types and thermal regimes. Another unique feature is the existence of five lobelia lakes. This name comes from the Latin name of the taxon – Lobelia dortmanna L. which has been included in the Polish Red Data Book of Plants. The chemical analysis included 55 parameters, within macro elements (MEs), trace elements (TEs) and rare earth elements (REEs). Low concentrations of MEs, TEs and REEs confirm the absence of anthropogenic pressure. High variation of ME, TE and REE contents between individual lakes is due to different geological structure. The cluster analysis enabled lakes to be divided into six groups taking into account all analyzed water quality parameters. The lobelia lakes were characterized by the lowest concentrations of MEs and REEs, which mainly result from the small catchment area and their mainly endorheic character. The highest variability of MEs, TEs and REEs occurred in endorheic lakes, where the geological structure was dominant. The lowest variability of MEs, TEs and REEs occurred in the lakes connected by the Struga Siedmiu Jezior stream. The analysis of MEs, TEs and REEs in relation to the environmental factors and trophic, hydrologic and thermal typology allowed a better understanding of their spatial distribution in the BTNP lakes. The obtained results indicate that the values of the studied elements were generally close to the average values noted in surface waters according to the Geochemical Atlas of Europe.

Trophic state of lobelia lakes subjected to strong anthropogenic pressure located close to the Tricity area (northern Poland)

Intensive and expansive human activity greatly accelerates the natural process of lake evolution. It is assumed that an increase in the rate of lake fertilization (often termed “eutrophication”) is the most common and most serious anthropogenic disturbance occurring in these aquatic geoecosystems. Lobelia lakes, one of the most valuable water bodies, are particularly exposed to this type of pressure. The article presents the trophic state of 13 lobelia lakes, located close to the Tricity area, in the northeastern part of the Kashubian Lakeland, which are not legally protected. These lakes represent different geoecosystems determining the rate of their natural evolution, and are subjected to various forms of anthropopressure (numerous summerhouses, fishing, waterside leisure and recreation). The trophic status of these lakes was assessed on the basis of the Carlson-type indices. The evaluation indicated that six of these lakes were in borderline mesotrophic-eutrophic state, and seven represented a significantly advanced eutrophic state.

Zooplankton communities in three adjacent softwater lobelia lakes of slightly differentiated morphology and trophic state

The paper presents the results of an investigation of physical-chemical features of water as well as rotifer and crustacean abundance and diversity measures, relating to the taxonomic richness and species diversity index, in three lobelia lakes differing in trophic status and morphometric features. The main purpose of this study was to establish the diversity of zooplankton communities in the open water area of lobelia lakes, including extracting species common for each lake and also to find environmental predictors which are responsible for the development of zooplankton communities. Despite the fact that the three studied lakes are of the same origin, located in the same vicinity and have generally similar environmental factors, zooplankton community structure revealed a great variation in reference to species diversity (only ca. 20% of the species were common for all lakes) and particularly in inhabiting species. Obrowo Lake had the most diverse assemblages of both rotifers and crustaceans compared to Modre and Pomysko lakes. In the taxonomic structure species that are rare for the Polish fauna, such as e.g. Holopedium gibberum and Heterocope appendiculata, occurred. Even though the examined lobelia lakes are ecosystems that undergo varying human-induced impacts, they still remain taxonomically very variable aquatic ecosystems, containing rare species of very high ecological status. The observed symptoms of deterioration of water quality, reflected in the zooplankton biocoenotic features, showed that the best conditions were attributed to Obrowo Lake in comparison with the two remaining lakes – Modre and Pomysko. Total nitrogen and chlorophyll a concentration were decisive for the distribution of zooplankton species in Pomysko and Obrowo lakes, while in case of Modre lake water reactivity and conductivity were of higher impact.

Surfactants: a real threat to the aquatic geoecosystems of lobelia lakes

Lobelia lakes are valuable elements of the natural environment. They are characterised by low trophy, mainly in-forest location and a high transparency of water. However, similarly to other surface waters, they are subjected to increasing anthropogenic pressures, a good indicator of which is the level of surfactants, also called surface-active agents (SAAs). The aim of the study was to evaluate the intensity of anthropogenic pressures in 13 selected lobelia lakes and 14 streams in the catchments of these lakes in Northern Poland, based on SAA concentrations in the waters of these water bodies. We collected one water sample from each of these water bodies and determined the concentrations of cationic, anionic and non-ionic SAAs. We then compared the results with data concerning the ways in which these catchments and water bodies are used. While ionic (cationic and anionic) SAAs were found to be present in all the 27 samples (with concentrations ranging from 0.05 to 0.51 mg dm−3), non-ionic SAAs were identified in 17 of 27 samples (from 0.00 to 2.43 mg dm−3) with three samples largely exceeding the maximum concentration values reported by other authors. We concluded that SAAs are a real threat to the aquatic geoecosystems of lobelia lakes and that the pressures of tourism and leisure have the greatest impact.

Types of Geoecosystems of the Lobelia Lakes of the Tricity Area

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, 1985, 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.

Pathogenic fungi in selected lakes in the „Bory Tucholskie” National Park

The occurrence of potentially pathogenic fungal strains in the 7 lakes of the Struga Siedmiu Jezior and in three lobelia lakes situated in the central part of the "Bory Tucholskie" National Park was investigated. Ten fungal species belonging to 4 genera: <i>Candida (C. humicola, C. famala, C. guilliermondii), Cryptococcus (C. neoformans, C. laurentii, C. albidus, C. unigutndalus), Rhodotoorula (R. rubra</i> and <i>R. glutinis</i>), and <i>Trichosporon (T. cutaneum)</i>, were recorded and analysed in the summers of 2001 and 2002

The disappearance of stonewort populations in lobelia lakes of the Kashubian Lakeland (NW Poland)

The subject of this work is a comparative analysis of stonewort populations in 5 lobelia lakes of the Kashubian Lakeland based on literature data from the mid-1970s and the authors’ own studies from 2006. In the 1970s 15 sites of 7 stonewort species: Chara delicatula, C. fragilis, C. tomentosa, C. rudis, Nitella flexilis, N. opaca and N. mucronata were recorded in the lakes under study. The populations of C. delicatula and N. flexilis occupied the area from 0.3 to 6 m deep and were characterized by 20% cover on average. Thirty years later, in 2006, the presence of only 6 out of 15 stands was confirmed: 3 of C. delicatula and 3 of N. flexilis. Thus, a total of 9 stands (60%) and 5 species (71%) had disappeared completely. The majority of the preserved populations survived in a vestigial form. Population areas of C. delicatula reached a depth of 2 m and their cover did not exceed 5%. Populations of N. flexilis occupied the littoral up to a depth of 7 m and had 10% cover. The disappearance of stoneworts was probably caused by both anthropogenic factors and natural processes.