Danuta Drzymulska

Developmental Changes in the Historical and Present-Day Trophic Status of Brown Water Lakes. Are Humic Water Bodies a Uniform Aquatic Ecosystem?

The long-term development of three humic lake ecosystems in Poland was investigated through palaeoecological analyses of sediment cores. These wetland records spanning the Holocene were analyzed for plant macroremains, degree of peat decomposition, sediment geochemistry along with radiocarbon dating. Morphological characteristics of the catchments and data on contemporary water quality and management approaches were integrated. Our research on the palaeoecology of humic lakes suggests two main states: humic and eutrophic-humic. Of the lakes studied, only one consistently presented features typical of the humic type. The other two showed various states, and dynamic patterns of transformation. The results indicate that these systems can change from humic to eutrophic-humic, and back again, in response to catchment-linked factors, climatic change and human impact. Thus determination of uniform pattern in the development of humic lakes is questionable. This suggests that a reassessment of brown water lakes is necessary.

Reconstruction of landscape paleohydrology using the sediment archives of three dystrophic lakes in northeastern Poland

Sediment layers of uniform age within lakes (isochrones) and their patterns reflect accumulation processes which can be correlated with hydrologic conditions in lake basins. The sedimentary archives in three small dystrophic lakes in northeastern Poland are described based on the correlation of local pollen assemblage zones in cores that were collected from the centers and margins of each lake. Past regional groundwater levels could be discerned from the shape of the isochrones, whether plane parallel or concave in configuration in relation to the lake basin shape. The concave configuration of the isochrones in the studied lakes shows that regional groundwater levels remained mostly high and stable throughout their history. The water levels in each lake during the Late Glacial and throughout the Holocene were different and no single, common water-level fluctuation pattern was identified in the three water bodies. The lack of such a finding suggests that the lakes are influenced dominantly by local hydrological factors.

Postglacial shifts in lake trophic status based on a multiproxy study of a humic lake

The long-term development of a humic lake ecosystem in Poland was investigated via palaeoecological analyses of age-dated sediment cores. Peat and lacustrine deposit records spanning approximately 12,000 years of lake history were analysed with regard to palynomorphs, plant macrofossils, degree of peat decomposition, Cladocera and geochemistry. Our study demonstrated the difficulty of classifying sediments deposited in humic lakes. We considered it inadequate to classify dy sediment exclusively using macroscopic criteria in the absence of geochemical parameters. Our study of the palaeoecology of the humic lake suggested three primary shifts in its trophic status: from oligotrophy to mesotrophy (Allerød-Boreal), to eutrophy (Atlantic), and to humotrophy (from the Sub-Boreal to the present). The results indicated that shifts in the trophic status occurred in response to climatic changes and factors linked to the catchment. The transformation from a clearwater lake of high trophic status to a humic lake was possible, such that the latter may originate not only from an oligotrophic lake. As a result of our pioneering study, we determined that a humic water body may even develop because of transformation of a eutrophic lake.

Late Glacial and Holocene vegetation changes in the Wigry National Park, NE Poland - new pollen data from three small dystrophic lakes

Abstract The main phases of the Late Glacial and Holocene development of vegetation in the Wigry National Park were reconstructed based on the pollen analysis of sediments from three small dystrophic lakes (Lake Suchar Wielki, Lake Suchar II and Lake Ślepe). At the current stage of research, the age of the studied deposits was determined by AMS radiocarbon dating of few samples only. This meant that the chronology of the investigated sections had to be estimated also indirectly using their palynological correlation with the radiometrically well-dated section from Lake Wigry. The obtained pollen data confirmed the picture of the postglacial vegetation changes of the Wigry National Park, which was based on earlier studies of Lake Wigry. Furthermore, it documented the existence, mainly in the Preboreal and Atlantic chronozones, of temporary changes in vegetation, which might be a reaction to a short-lived cold fluctuations of climate.

Erratum to: Development of bog-like vegetation during terrestrialization of polyhumic lakes in north-eastern Poland is not accompanied by ecosystem ombrotrophication

The aim of the present study was to use the analysis of surface water chemistry to understand vegetation succession pathways in terrestrializing polyhumic lakes. We hypothesized that Sphagnum mire development was accompanied by a decrease in the mineral content in water. A total of 111 vegetation plots along 23 transects were analysed in 11 lakes and adjacent peat lands in the Wigry National Park (NE Poland). The vegetation of the lake-mire systems forms distinct zones: (1) nymphaeid-, bladderwort- and bryophyte-dominated aquatic vegetation; (2) sedge-dominated edge of the Sphagnumcarpet; (3) quaking, extremely poor fen with various Cyperaceae; (4) non-quaking, Eriophorum vaginatum-dominated bog-like vegetation and (5) pine woodland. Surface water corrected conductivity (ECcorr.), pH, COD-KMnO4 and Ca2+, Mg2+, Fetot. and SiO2 were measured along the transects. The environmental gradients best explaining the observed pattern were pH (with the highest values in the lake and the lowest in the bog-like vegetation) and COD-KMnO4 (showing an inverse direction). At least in some Sphagnum-mires conditions were more minerotrophic than in the lakes. The process of humic lake overgrowing by Sphagnum-mires in NE Poland results in pine woodlands on mineralised peat. The climate conditions in NE Poland, combined with evapotranspiration accelerated by encroaching trees, do not seem to support the development of ombrotrophic bogs.

On the history of Brasenia Schreb. in the European Pleistocene

Brasenia Schreb. is a monotypic genus in the Cabombaceae, present nowadays on all continents except Europe and Antarctica. This thermophilous aquatic plant, which originated in the Tertiary, was a frequent element of aquatic plant life during the interglacial stages of the European Pleistocene. A systematic review of the palaeobotanical records of Brasenia pollen and seeds reveals its history in Europe from the Plio-Peistocene until the Eemian interglacial. Remains of Brasenia were typical for the climatic optima during each of these stages of the Pleistocene. In this paper the diversity of fossil Brasenia species is also shown. The most abundant and morphologically diverse seeds were found in sediments from eastern European sites. Brasenia species became extinct in Europe at the end of the last interglacial or at the beginning of the Weichselian glaciation. Different scenarios for their disappearance are proposed, including the specificity of the floral cycle, probable poor dispersal of seeds, or the scarcity of suitable water bodies for it to survive.