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Abstract

Based on geochemical and biological investigations of a 6-m-long sediment core, a reconstruction of the environmental conditions in Charzykowskie Lake (northern Poland) is presented. The analyzed sediments consist of fine calcareous detritus gyttja interbedded by lake marl. The results of palynological analysis document the vegetation development around and in the studied lake and confirm the middle and late Holocene age of the sedimentation of the deposits. The identification of 22 taxa of subfossil Cladocera shows the biodiversity of the fauna and reflects the changes in the trophic and water level. The concentrations of various chemical elements suggest the origin of the sediments. Geochemical, including isotope, and biological data, made it possible to reconstruct the environmental conditions, as well as traces of human influence over the last ca. 6,200 years. Four stages of human impact have been documented by the pollen data. The first traces of human groups in the vicinity of Charzykowskie Lake are preserved in sediments from about 4,000 years ago. The human activity is poorly recorded in the Cladocera and in the geochemical compositions of the lake sediments, probably due to the size and depth of the lake and its isolation.
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Authors and Affiliations

Joanna Mirosław-Grabowska
1
Edyta Zawisza
1
Milena Obremska
1
Joanna Kowalczyk
1
Łukasz Zbucki
2
Kazimierz Tobolski

  1. Institute of Geological Sciences, Polish Academy of Sciences, Research Centre in Warsaw, INGPAN, Twarda St. 51/55, 00-818 Warsaw, Poland
  2. John Paul II University of Applied Sciences in Biała Podlaska, Faculty of Economics Sciences, Sidorska St. 95/97, 21-500 Biała Podlaska, Poland
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Abstract

This paper gives a description of the head shield of Alona protzi, a rare species of Cladocera (water fleas) whose separated head shield has not yet been described in detail. Subfossil head shields of A. protzi were found in sediment cores taken from lakes in Denmark, Sweden, Finland, Estonia and Poland. Despite the rarity of the species this suggests a wide distribution of A. protzi in northern Europe. The ecology of A. protzi is poorly known. The environmental spectrum of the finding sites was wide and ranged from relatively nutrient poor clear water lakes to eutrophic turbid water lakes, indicating that A. protzi is not narrowly restricted. Most of the lakes were, however, meso-eutrophic with neutral to high pH, and with a relatively low abundance of submerged macrophytes. However, we cannot exclude the possibility that A. protzi mainly lives in groundwater and is only occasionally transported into lakes.

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Authors and Affiliations

Rikke Bjerring
Mirva Nykänen
Kaarina Sarmaja-Korjonen
Artem Sinev
Karina Jensen
Liisa Nevalainen
Krystyna Szeroczyńska
Edyta Zawisza
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Abstract

This paper presents discussion on the results of subfossil Cladocera analyses from five lakes in Poland (Przedni Staw Lake, Perespilno Lake, Gościąż Lake, Imiołki- fossil lake and Ostrowite Lake). The Cladocera are represented in sediments by remains of planktonic (Bosminidae, Daphnidae) and littoral (Chydoridae) forms. Cladoceran assemblage phases ("ecostratigraphy") were determined on the basis of changes in dominance of indicator species and past ecological conditions were reconstructed. The results are being discussed from the viewpoint of climate change and anthropogenic activity and their role in the lake evolution. Moreover, an attempt to use the cladoceran phases for stratigraphic division of the Late Glacial and Holocene was made. During the Bolling/Allerod interstadial, distinguished on the basis of Pollen analysis, Cladocera indicated short phase of bad condition (dry or cold?), probably as the Old Dryas climate results. The beginning of Holocene are characterized, in mountain and lowland lakes, by high increase in the number of species and specimens of Cladocera. This described clear warming and marked the boundary Late Glacial/Holocene. It was indicated that the "ecostratigraphy" based on Cladocera can be useful for climatostratigraphy, if climate was the major factor controlling the development of freshwater lakes.
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Authors and Affiliations

Krystyna Szeroczyńska
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Abstract

In this study we compared chydorid cladoceran (Chydoridae) taxa and assemblages from sediments of 6 Polish and 6 Finnish lakes and investigated if the difference in climate of these two countries can be detected in the cladoceran data. The data were analysed in terms of I) average relative proportions of chydorid taxa during the history of each lake and by 2) redundancy analysis (RDA) to explain the present effect of environmental variables (altitude, area, maximum depth, mean annual temperature, mean summer temperature and length of the growing season) on species abundances. The redundancy analysis (RDA) enabled us to distinguish groups of taxa I) with a high thermal preference 2) associated with small, cold-water lakes and 3) associated with shallow lakes. There are clear differences in the dominant chydorid taxa and in the relative proportions of many other chydorid taxa between the two countries since the end of the last glaciation. Although these differences first of all appear to reflect the climatic difference, the influence of many other environmental factors, controlling the living conditions of particular chydorids have been raised and considered. Further studies with larger data are needed before the role of climate can be reliably separated from other elements of environment.
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Authors and Affiliations

Kaarina Sarmaja-Korjonen
Krystyna Szeroczyńska
Michał Gąsiorowski
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Abstract

The present work is a part of the development of a method which uses the relative proportions of asexually and sexually reproducing chydorid females to reconstruct the length of the open-water season. Surface sediments (5 cm) of Lake Aitajärvi, northern Finnish Lapland, were examined for modern and recent proportions of chydorid cladoceran ephippia in subarctic climate near the pine limit. The total chydorid ephippium proportions (TCE) were steadily 9.5-9.7 % in the Aitajärvi sediment but declined to 8.4 % in the uppermost sample. The result was compared with the surface sediment TCE from four lakes in southern Finland where it varied between 3-6%. It was also compared with the TCE from two lakes in northernmost Finnish Lapland above the treeline in very severe climate, where it was 26-30 %. These very high values suggest that there might be a threshold in climate conditions between Aitajärvi and the two northernmost lakes that alters the reproduction of chydorids towards an even more important role of sexual reproduction.
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Authors and Affiliations

Kaarina Sarmaja- Korjonen

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