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1

Environmental changes during the last millennium recorded in subfossil Cladocera, diatoms and sediment geochemistry from Lake El Sol (Central Mexico)

Zawisza E., Cuna E., Caballero M, Ruiz-Fernandez A. C., Szeroczyńska K., Woszczyk W., Zawiska I.

Geological Quarterly

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2017

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Vol. 61, No. 1

81--90

EN

High-altitude lakes, which are very sensitive ecosystems and respond rapidly to climatic changes, are one of the best targets for palaeolimnological studies. Here, we present the record of environmental changes over the last millennium that are recorded in the sediments of El Sol, a tropical, high-altitude, volcanic crater lake on the Nevado de Toluca, Central Mexico. Palaeolimnological reconstructions are based on subfossil Cladocera, diatoms, magnetic susceptibility and chemical analysis of the sediments. In general, Cladocera occurring in tropical regions, and especially at high altitude, have been studied very little. Our data indicate that in the sequence studied, the species diversity of subfossil Cladocera is very low. Only four species were recorded, and the assemblage is dominated by littoral species. Two Cladocera taxa, Alona manueli and Ilyocryptus, found at Lake El Sol are endemic. Cladocera, diatoms and the sediment chemistry show changes in Lake El Sol which are mostly related to climate. The most pronounced climatic signal was obtained for the early Little Ice Age (1350–1625 AD). This cold episode was expressed by a reduction in the frequency of zooplankton (individuals/cm2/yr) and diatoms (valves/g of dry sediment) and by changes in the organic carbon content in the sediment. Our results show that human activity was very limited throughout the study period. According to historical data the presence of humans at the lake shore was mostly occasional, usually for ceremonial and ritual purposes, and humans did not have an important influence on the lake ecosystem. Only one period was identified when human activity was important. This period corresponds to the introduction of fish into the lake at the beginning of the 20th century.

2

Initial Time of Two High Altitude Crater Lakes (Nevado De Toluca, Central Mexico) Recorded in Subfossil Cladocera

Szeroczyńska K., Zawisza E., Wojewódka M.

Studia Quaternaria

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2015

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Vol. 32, Nr 2

109--116

EN

The objective of this study was the recognition and reconstruction of the origin of two high altitude lakes and the ecological conditions of their early existence based on subfossil Cladocera and chemical analyses. The study focused on the oldest lacustrine sediments from Lake Sol and Lake Luna, located in the crater of Volcano Nevado de Toluca (Central Mexico). The Nevado de Toluca crater developed approximately 12 ka yr BP. According to the literature, the volcano was last active approximately 3.3 ka yr BP, and the lakes developed after that eruption. The remains of nine Cladocera species were found in the bottom sediments of both lakes. The most dominant taxa were two endemic littoral species: Alona manueli and Iliocryptus nevadensis. The total frequency of Cladocera specimens in both of the sediment cores was very low. No Cladocera remains were recorded in the sediment layer at depths between 123–103 m from Lake Luna. The results of the lithological and geochemical analyses showed that this sediment layer was composed of allochthonous material, probably originating from slid down from the volcanic cone. This was suggested by the content of silica (up to 13%), iron (up to 12%), and titanium (up to 4%). The Cladocera remains recorded in the bottom sediments suggested that both reservoirs developed as freshwater lakes at the beginning of the sedimentation. The calibrated radiocarbon dates obtained for the bottom samples were 4040 to 3990 yr BP for Lake Luna (129 cm) and 4485 to 4485 yr BP for Lake Sol (89 cm). The obtained ages were older than the dates of the last eruption, which occurred approximately 3300 yr BP. This result was likely related to the type of radiocarbon dated materials (charcoals).

3

Cenotes – lakes of the Yucatan Peninsula (Mexico)

Szeroczyńska K., Zawisza E.

Studia Quaternaria

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2015

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Vol. 32, Nr 1

53--57

EN

Cenote lakes are natural sinkholes or depressions resulting from the collapse of limestone bedrock exposing the groundwater underneath. Thousands of such lakes are particularly encountered on the Yucatan Peninsula (Mexico). These lakes were of great significance for the Maya culture as important religious places and primary source of drinking water. They permitted the survival of Mayan communities through dry periods known as “Maya drought”. Most of the cenote lakes are large open water pools measuring tens of meters in diameter. The majority of cenotes are smaller sheltered sites. Their waters are usually very clear and oligotrophic, originating from rain water filtering slowly through the ground. The authors visited and collected zooplankton samples from eight cenotes in November 2013, namely: Ik-Kil, Samula, Zaci, X-Kekn, Actum Ha, Cristal, Sian Ka’an, and Chan Chemuxil (transect Merida–Tulum– Cancun). The analysed lakes differ considerably in morphological terms, varying from very deep to shallow. Some of them are under human impact (tourists). The water samples were analysed for zooplankton content, but the phytoplankton frequently occurring was also taken into account. The obtained results are largely varied, indicated big eco- logical verity among cenotes which depended on lake age, localization and morphometry. As showed our study Cladocera zooplankton was very rare and only present at several sites. Between the fauna community Copepoda and Ostracoda species were the most abundant. Phytoplankton were present in all studied lakes and it sees that played the central role in those ecosystems.

4

Algal and invertebrate microfossil assemblages from lake sediments in the reconstruction of past community dynamics - preliminary information

Antipushina Z, Szeroczyńska K, Zawisza E.

Studia Quaternaria

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2012

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Vol. 29

53--58

EN

This paper focuses on the usefulness of a palaeolimnological method called the joint algological and zoological analysis. The joint algo-zoological analysis involves counting all identifiable remains of the main algae groups (Bacillario- phyta, Cyanophyta, Desmidiales, other Chlorophyta, Trachelomonas sp.) and invertebrate groups (Cladocera, Ostra- coda, Chironomidae, Chaoborus sp., and other insects, Turbellaria, Bryozoa, Spongia and Testacida) in volumetric samples. We present results from recent sediments of Lake Glubokoe (Moscow region, Russia) as an example of the application of this method. We reconstruct the structure of phytoplankton, zooplankton and zoobenthos communities and their dynamics over the last 25 years. Our results support the validity of this method in the reconstruction of the structure of phyto- and zooplankton communities and their dynamics, information that may be lost when carrying out separate analyses for individual groups. Simplicity is another advantage of this methodology.

5

Description of the subfossil head shield of Alona protzi hartwig 1900 (anomopoda, chydoridae) and the environmental characteristics of its finding sites

Bjerring R., Nykanen M., Sarmaja-Korjonen K., Sinev A., Jensen K., Nevalainen L., Szeroczyńska K., Zawisza E.

Studia Quaternaria

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2008

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Vol. 25

47-53

EN

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.

6

The development history of Wigry Lake as shown by subfossil cladocera

Zawisza E., Szeroczyńska K.

Geochronometria

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2007

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Vol. 27

67-74

EN

Environmental changes in Wigry Lake during the Late Glacial and Holocene were studied on the basis of subfossil Cladocera analysis. Cladocera are present in a long core WZS/03 (Słupiańska Bay), and a surface sediments. The sediment contains remains of twenty-seven species belonging to 5 families. Species composition of plankton and the variability in the frequency of specimens of Cladocera made possible to distinguish five phases of their development, which well correlated with palynological phases. The correlation proves that the biological development of Wigry Lake was determined mainly by climatic changes. During the history of the lake, planktonic forms were dominant and represented by Bosminidae. It indicates that the lake was (excluding the initial part) deep and oligo- or mesotrophic. The mesotrophic state has been noted during the Atlantic chronozone and temporary. Taking into consideration the size and the depth as well as the rare human population around the lake it can be stated that the trophy rise was the result of the warm climate. It is also possible that during the last few decades the natural and anthropogenic factors could add. Probably mild winters, warm and long summers, increased tourists number were partly responsible for changes of water state.

7

The significance of subfossil Cladocera in stratigraphy of Late Glacial and Holocene

Szeroczyńska K.

Studia Quaternaria

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2006

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Vol. 23

37-45

EN

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.

8

Daphnia remains from the sediment of lake somaslampi (nw finnish lapland) and Lake Wigry (ne Poland)

Szeroczyńska K., Zawisza E.

Studia Quaternaria

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2005

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Vol. 22

55-57

EN

In this paper remains of Daphnia found in the sediments retrieved from Lake Somaslampi (NW Finnish Lapland) and Lake Wigry (NE Poland) are presented and compared with Daphnia remains found by D.G. Frey in Greenland. Daphniapulex haedshields and shells were found in the early Holocene sediments of Lake Somaslampi. In the early Holocene sediments of Lake Wigry only postabdominal claws and ephippia of Daphnia were abundant, but in the sediments deposited during the last 50 years very well preserved shells of Daphnia longispina-group were found. The prezent findings indicate that the good preservation of Daphnia haedshields and shells may be more common than previously thought. It is possible that the special conditions they need to be preserved is cold climate.

9

Subfossil chydorid taxa and assemblages from lake sediments in Poland and Finland with special reference to climate

Sarmaja-Korjonen K., Szeroczyńska K., Gąsiorowski M.

Studia Quaternaria

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2003

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Vol. 20

25-34

EN

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 1) 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 distinguih groups of taxa 1) 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.

10

Palaeohydrological aspect of transformation of lakes into peat bogs during middle holocene on the basis of cladocera analysis in the northern Poland

Szeroczyńska K., Gąsiorowski M.

Studia Quaternaria

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2002

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Vol. 19

55--60

EN

Cladocera are a group of water animals, which are strongly dependent on environmental conditions. The ratio of planktonic to littoral Cladocera species is a widely used tool in palaeohydrological reconstruction of lakes' water level changes. Interpretation of this ratio is still unclear and requires further evidence. The simplest indicator of water level, which can be used in tracing lake-peat bog transitions, is the presence or absence of Cladocera and the character of its disappearance. In general, two models of Cladocera decline are observed. The first model is characterized by a very abrupt disappearance of all species, whereas the second one, with an intermediate stage, is characterized by domination of specific species. These two models are related to different types of terminal history of the water body. Even after a total disappearance of water in the peat bogs, there were episodes of some pioneer cladoceran species presence, correlated with periods of humid climate.

11

Wioślarki (Cladocera, Crustacea) jako źródło informacji w badaniach osadów jeziornych

Szeroczyńska K.

Studia Geologica Polonica

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1998

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Vol. 112

9-28

PL

Znaczenie analizy szczątków Cladocera w badaniach paleolimnologicznych potwierdzają zaprezentowane wyniki osiągnięte w Polsce i zagranicą. Opisano po krótce metodę preparacji i oznaczania szczątków. Podkreślono znaczenie stosowania mikroskopu skaningowego w celu prawidłowego oznaczenia gatunków. Często znajdowane są skorupki o różnej strukturze, a należące do tego samego gatunku, co prawdopodobnie związane jest z różnymi warunkami egzystencji. Przedyskutowano interpretację danych, wskazując na duże znaczenie form planktonowych, zwłaszcza gatunków z rodziny Bosminidae. Gatunki Chydoridae odzwierciedlające głównie stan strefy brzegowej przedstawiono według grup wskaźnikowych wydzielonych przez różnych badaczy.

EN

The chitinous fragments of Cladocera carapaces, frequently found in lacustrine sediments, are valuable material for palaeolimnological studies. On the basis of species composition of Cladocera it is possible to restore the development of the lake, including its trophic changes and water level fluctuations. The importance of analyses of subfossil Cladocera in palaeolimnological investigations is accentuated by the results hitherto obtained in many countries (Frey, 1986a; Korhola, 1990; Hofmann, 1993). A review of previous research in this domain is presented in this paper, alongside with the methodology of analytic works and interpretation of the results. The most frequently used and very useful method of preparation of Cladocera remnants from gyttja sediments is described (Frey, 1986a). It has been shown that determination of Cladocera remnants using biological microscope alone may lead to taxonomic errors. For instance, the present author has found that carapaces belonging to Chydorus sphaericus, when seen under scanning microscope, differed considerably in their structure. In my opinion, the differences in structure within the same species may be a result of various lake conditions. Hence, the need to use scanning microscope in solving taxonomic problems is emphasised (Figs. 1-4). The results of analyses of changes in the frequency and species composition of Cladocera are particularly useful in reconstructions of lake evolution. The planktonic forms, mainly the species of the Bosminidae family, are particularly important in determining trophic changes and water level fluctuations (Alhonen, 1970; Hofmann, 1986, 1993; Szeroczyńska, 1998a). The species of the Chydoridae family, characterising mainly the littoral environment, are presented according to the index groups established by some authors (Flössner, 1990; Hofmann, 1986; Korhola, 1990). Particular species of this family make a basis for determination of the diversity and equitability, as well as pH, providing to some extent climatic information (Frey, 1988b; Hofmann, 1986; Krause-Dellin, 1988; Whiteside, 1970).

12

Holoceńska historia jezior Lednickiego Parku Krajobrazowego na podstawie kopalnych wioślarek

Szeroczyńska K.

Studia Geologica Polonica

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1998

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Vol. 112

29-103

PL

Opracowanie przedstawia wyniki analizy subfosylnych Cladocera, którą wykonano w osadach profili czterech jezior: Lednickiego, Kamionek, Linie i Skrzetuszewskiego. Jeziora położonone są blisko siebie w obrębie Lednickiego Parku Krajobrazowego (koło Poznania). W osadach jezior fauna Cladocera reprezentowana jest przez gatunki planktonowe (P), głównie z rodziny Bosminidae, oraz litoralne (L), głównie z rodziny Chydoridae. Ich frekwencja, a także stosunek form planktonowych do litoralnych (P/L) odzwierciedlają warunki morfologiczne przebadanych jezior. Uzyskane wyniki przedstawiono na diagramach, na których uwzględniono również wyniki analiz palinologicznych. Skład gatunkowy i frekwencja osobników Cladocera są podstawą rekonstrukcji rozwoju jezior Lednickiego Parku Krajobrazowego. Dla każdego jeziora wydzielono fazy rozwoju Cladocera w okresie holoceńskim. Ponadto wydzielono etapy wzrostu trofii w jeziorach (od 2 do 6) i okresy wyższego i niższego poziomu wód. Fazy rozwoju Cladocera częściowo korelują z okresami klimatycznymi i lokalnymi fazami pyłkowymi, a etapy wzrostu trofii - z fazami osadniczymi. Trofia w poszczególnych jeziorach kształtowała się nieco odmiennie. Uzależniona była głównie od wielkości i możliwości produktywnych jeziora. Korelacja etapów wzrostu trofii w jeziorach z fazami osadniczymi pozwala przypuszczać, że w niektórych przypadkach wzrost trofii był przede wszystkim wynikiem nadmiernego dopływu nutrientów do jeziora, co spowodowane zostało prawdopodobnie działalnością osadników w sąsiedztwie. Najwyższy stan trofii stwierdzono w okresie średniowiecza.

EN

An analysis of subfossil Cladocera was conducted on sediment cores taken from four lakes. The investigated lakes are situated close one to another in the Lednica Landscape Park near Poznań (Fig. 1). In the centre of this park one of the largest lakes of this region, Lake Lednickie, occurs. On its island, the former seat of the first Polish Piasts was located (Kurnatowska, 1989). Interdisciplinary research conducted in the park began in the 1980?s and included broadly understood historical and natural science disciplines (Łopacka-Szymańska, 1989, 1991, 1994). The questions connected with the beginnings of the Polish statehood brought together not only historians, but also archaeologists and naturalists, grouped under the leadership of Prof. Z. Kurnatowska (Dzięciołowski & Górecki, 1989). For several tens of years, research attempting to reconstruct ecological changes which occurred in the Lednica Landscape Park, has been conducted (Filbrandt-Czaja, 1992; Makohonienko, 1991; Tobolski, 1989a, b, 1991b, 1993b, c, 1996). Particular emphasis has been put on palaeobotanical research, with a view to reconstruct changes in vegetation and establish a detailed stratigraphic scheme. Palaeobotanical research included also the study of diatoms (Bogaczewicz-Adamczak & Tobolski, 1991; Pieścikowski, 1990, 1994). The sediments of some lakes were as well the subject of palaeolimnological analysis for the content of Insecta (Lemdahl, 1991) and Cladocera (Szeroczyńska, 1991a, b). An analysis of Cladocera was performed on the sediment cores taken from four lakes: Lake Lednickie, Lake Kamionek, Lake Linie and Lake Skrzetuszewskie. The Lednica Landscape Park will also be studied in the future. This is why broadly based research of contemporary flora and fauna has been conducted (Burchardt, 1990, 1996; Burchardt et al., 1990; Kuczyńska & Romanowicz, 1990; Michałkiewicz, 1990; Pańczakowa, 1990; Tobolski, 1993b).

13

Cladocera w osadach pelagicznych Jeziora Biskupińskiego

Szeroczyńska K., Polcyn. I.

Studia Geologica Polonica

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1998

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Vol. 112

105-122

PL

Przedstawiono wyniki analizy szczątków Cladocera osadów z profilu 5, pochodzącego z głębokiej strefy Jeziora Biskupińskiego. Wyniki stanowią materiał uzupełniający dane, które uzyskano w roku 1995 z analizy osadów profilu 4 pochodzącego ze strefy litoralnej. Sedymentacja osadów odwierconych w profilu 4 obejmuje okres od fazy inicjalnej jeziora (alleröd) po czasy współczesne, a osady z profilu 5 odłożone zostały w okresach subborealnym i subatlantyckim. W związku z tym dokonane porównanie wyników dotyczy tylko neoholocenu. Duża frekwencja planktonowych osobników Cladocera w profilu 5 pozwoliła na szczegółowe prześledzenie procesu eutrofizacji jeziora, jak również wahań poziomu wody. Wydzielono 5 etapów wzrostu trofii oraz stwierdzono wyższy poziom wód w jeziorze w drugiej połowie okresu subborealnego i w okresie subatlantyckim, w czasie wędrówki ludów. Etapy wzrostu trofii są częściowo zbieżne z fazami rozwoju gospodarki ludzkiej, a określone poziomy wahań wody z wynikami badań paleohydrologicznych. Wydzielono również 3 fazy i 6 podfaz rozwoju Cladocera, które odpowiadają fazom klimatycznym oraz lokalnym fazom pyłkowym.

EN

The first analyses of the content of Cladocera within sediments of the Biskupin Lake were performed in 1994 (Szeroczyńska, 1995). The section (core 4) studied comes from the littoral zone of the lake, where sedimentation lasted from the initial phase of the lake (Alleröd) until contemporary times. These results turned out to be insufficient to conduct a full reconstruction of the lake?s history. Hypotheses on the biological development of the lake are based mainly on changes in the species composition of the plankton. The sediments of core 4 contained primarily remains of species of the littoral zone, and planktonic species consisted mainly of allochthonous material, washed in by waves. Hence, their presence and frequency were of circumstantial value, and did not present the real picture of changes which occurred in the lake during the Holocene. In 1996, in order to obtain a complete picture, an additional analysis of Cladocera remains was performed on the sediments of core 5, drilled in the pelagic zone, at a place where the water depth exceeded 10 m. Microscopic analyses were performed by I. Polcyn and interpreted by K. Szeroczyńska. The sediments were deposited only during the Subboreal and Subatlantic periods, despite relatively large thickness of 9 m. Therefore, it was possible to study the changes which occurred exclusively during the Neo-Holocene. The thickness of these sediments allowed for a detailed interpretation of the periods during which they were deposited. An analysis of subfossil Cladocera was performed on 83 samples, spaced every 2 to 10 cm. 32 Cladocera species belonging to 6 families were found. The species composition was very close to that encountered in the sediments of core 4 (Szeroczyńska, 1995). Only the count of individual species was different. The results obtained are presented graphically in percentage and absolute value diagrams (Figs. 2, 3, 4), and compared with those of the analyses of core 4 (Fig. 5). Furthermore, the diversity diagram and species composition of forms connected with a certain pH were constructed for both cores (Fig. 6). On the basis of species composition and frequency of Cladocera specimens, changes in the lake during the Subboreal and Subatlantic periods were characterised. The zones of Cladocera development were established, their numbering corresponding to that of the zones distinguished in core 4. The Subboreal period is represented by one zone (Va, b, c) of Cladocera development. The species composition and the frequency of individuals indicates that during this period the lake was dominated by planktonic forms. The share of littoral forms was small, except for the acidobiontic species Alonella excisa. During the Subboreal period this species achieved maximum development, and in the sediments of core 5 larger amounts of its remains were found, as compared to cores taken from the littoral zone. Near the end of the Subboreal period, the count of Alonella excisa declined, and this species never reached such a share among the species of Chydoridae. In the Subatlantic period, two zones of Cladocera development have been distinguished (Zone VIa, b, c, Zone VII). The lake was dominated at that time by species connected with higher trophy. It is probable that this was a period of progressive eutrophication of the lake, particularly from Zone VIb onwards. A smaller share of planktonic forms (approximately 30%, except for Bosmina longirostris), indicates a somewhat higher water level. Only in the sediments at a depth of 400-370 cm, whose sedimentation probably occurred during the Migration period, a share of planktonic forms did exceed 50% (including only 10% of Bosmina longirostris). Near the end of the Subatlantic period, a change in the species composition of Cladocera was noted. An increased share was shown again by planktonic forms (approximately 70%, including 20% of Bosmina longirostris), and the littoral forms, including Chydorus sphaericus, did not exceed 30%. This period, despite its short duration, was distinguished as a separate zone (VII), and it is also reflected in other lakes of the Polish Lowlands (Szeroczyńska, 1998a, b). The characteristics of Cladocera development in the Biskupin Lake indicate that the development of the lake was directly influenced by the climate and economic activity of man. The zones of Cladocera development found in sediments of cores 4 and 5, correspond in part with the climatic periods, as well as local pollen phases (Noryśkiewicz, 1995). The CONSLIK diagrams (Fig. 7) confirm this assignment. On the basis of the frequency of species preferring more fertile waters, 5 phases of increased trophy in the lake (two in the Subboreal and three in the Subatlantic period) were identified. These phases correspond in part with the periods of increased trophy, distinguished on the basis of diatom analyses (Bogaczewicz-Adamczak, 1995), and the phases of human influence, distinguished on the basis of palynological studies (Noryśkiewicz, 1995). It can be supposed, therefore, that the phases of increased trophy in the lake were, to a certain degree, a result of the activity of the settlers. This is confirmed by the fact that the periods of decreasing trophy correlate with phases without appreciable influence of human activity. A large frequency of planktonic remains in the sediments studied allowed for a thorough analysis of water levels in the lake, adding to the conclusions drawn from analyses of the sediments of core 4. A somewhat higher water level can be deduced from the sediments occurring at depths of 760-660 cm, 630-600 cm, 400-370 cm, as well as at the surface. A lower water level in Lake Biskupin occurred at the time of sedimentation at depths of 860-850 cm, 660-630 cm, 600-580 cm, and 380-350 cm. The above-mentioned periods of lower and higher water levels are conformable to the palaeohydrological interpretations by Niewiarowski (1995a, b) and Noryśkiewicz (1995) and, partially, to those based on the dominant planktonic or littoral diatom species (Bogaczewicz-Adamczak, 1995). As shown by analyses of subfossil Cladocera, a somewhat lower water level during the second half of the Subboreal period, as well as during the Subatlantic period, at the time of the Migration of the Peoples, is supported by palaeohydrological interpretations of other lakes (Gaillard, 1985; Niewiarowski, 1978; Ralska-Jasiewiczowa and Starkel, 1988; Szeroczyńska, 1991, 1998a).

14

Antropogenic transformation of nine lakes in Central Poland from Mesolithic to modern times in the light of Cladocera analysis

Szeroczyńska K.

Studia Geologica Polonica

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1998

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Vol. 112

123-165

EN

This paper reviews the influence of human economy of various settlement cultures on the state of lakes. The review was conducted on the basis of littoral and planktonic Cladocera forms in comparison with palynological data concerning the occurrence of synanthropic plants. The obtained results proved that management of resources by humans may be determined not only by means of changes in vegetation of lakeside, but through changes in the species composition of Cladocera in the lakes, as well. The diagrams show a distinct correlation between the curves reflecting changes in the occurrence of synanthropic plants and the frequency of Cladocera species showing increased trophy. A correlation was established between the share of the algae Pediastrum (mainly P. boryanum) and the Chydorus sphaericus count. A relationship was noted between the level of development of settlement cultures and the population size and the intensity of its influence on the eutrophication of lakes. It was also noted that the smaller the lake, the clearer the record of changes in trophy. It was shown that, among all the settlement cultures, the greatest influence on the state of the lakes was exerted by those of medieval and modern times, causing the greatest degradation. This influence resulted in accelerated eutrophication, and the main component of plankton became Bosmina longirostris and Chydorus sphaericus indicative of a high trophy.