Papers by Izabela Zawiska
Geographia Polonica
We present a training set, the database involving physical-chemical water parameters together wit... more We present a training set, the database involving physical-chemical water parameters together with the subfossil Cladocera and diatoms community composition in the surface sediments of 64 postglacial lakes in NE Poland sampled along a wide trophic gradient (from oligo- to highly eutrophic). The most important water parameters measured in water were chlorophyll-a, electrical conductivity (EC) and oxygen concentration. In addition, total phosphorus (TP) and Secchi depth (SD) were determined for the surface water layer. The data collected will be used to calculate a transfer-function for quantitative reconstruction of trophic state in freshwater temperate lakes.
Quaestiones Geographicae
The paper presents an application of interpretative machine learning to identify groups of lakes ... more The paper presents an application of interpretative machine learning to identify groups of lakes not with similar features but with similar potential factors influencing the content of total phosphorus – P tot. The method was developed on a sample of 60 lakes from North-Eastern Poland and used 25 external explanatory variables. Selected variables are stable over a long time, first group includes morphometric parameters of lakes and the second group encompass watershed geometry geology and land use. Our method involves building a regression model, creating an explainer, finding a set of mapping functions describing how each variable influences the outcome, and finally clustering objects by ’the influence’. The influence is a non-linear and non-parametric transformation of the explanatory variables into a form describing a given variable impact on the modeled feature. Such a transformation makes group data on the functional relations between the explanatory variables and the explained...
Limnetica, 2019
Dystrophication of lake Suchar IV (NE Poland): an alternative way of lake development The long-te... more Dystrophication of lake Suchar IV (NE Poland): an alternative way of lake development The long-term dynamics of a lake development and the role of the catchment and climate change in the dystrophication process were studied. Lacustrine sediments from Lake Suchar IV, NE Poland (880 cm long core), were selected for paleolimnological studies. The paleoecological reconstruction was based on pollen, subfossil cladocerans, diatoms, macrofossils and chemical analyses. Sediment chronology was based on the results of 14 C dating and palynological analysis. The obtained data showed that the lacustrine sedimentation at Lake Suchar IV began in the Late Glacial and continues to this day. The plant succession indicates that sedimentation processes started as early as the Oldest Dryas ~ over 15 000 cal yr BP ago. Important changes in the pollen spectrum of aquatic plants were noted from the mid-Atlantic period. At that time, communities of Nymphaea and most species of green algae disappeared from the lake, which indicates a significant ecological transformation in the aquatic environment. This transformation is also manifested in the subfossil Cladocera and diatom communities. The Cladocera community in the sediments of Lake Suchar IV was represented by 37 species, mostly littoral ones. From the transition time (7200-5600 cal yr BP), Cladocera communities were dominated by taxa tolerant of acidification such as Alonella excisa, Acroperus harpae, Alona affinis and Alonella nana. A total of 193 diatom taxa (species and varieties) were identified in the sediment, including 172 belonging to Pennales and 21 to Centrales. In general, the diatom community was dominated by alkaliphilous-on average 45 % of the species composition. In terms of trophic preferences, the largest group of diatoms was represented by oligotraphentic, meso-eutraphentic and eutraphentic taxa. No diatoms were present during about 6000 cal yr BP from the transition stage. Sediment geochemistry and macrofossils also indicate the limnological development and climate trends. The obtained paleolimnological results indicate that Lake Suchar IV has undergone an ecological transformation from a harmonic to disharmonious ecosystem. During the Late Glacial and the early Holocene, Lake Suchar IV was a typical harmonic lake that transformed into a dystrophic state at the end of the Atlantic period. Sediments of Lake Suchar IV also show a very interesting sequence of trophic changes, from oligotrophic to mesotrophic and to dystrophic conditions.
Water, 2020
Cultural eutrophication, the process by which pollution due to human activity speeds up natural e... more Cultural eutrophication, the process by which pollution due to human activity speeds up natural eutrophication, is a widespread and consequential issue. Here, we present the 85-year history of a small, initially Lobelia–Isoëtes dominated lake. The lake’s ecological deterioration was intensified by water pumping station activities when it received replenishment water for more than 10 years from a eutrophic lake through a pipe. In this study, we performed a paleolimnological assessment to determine how the lake’s ecosystem functioning changed over time. A multi-proxy (pollen, Cladocera, diatoms, and Chironomidae) approach was applied alongside a quantitative reconstruction of total phosphorus using diatom and hypolimnetic dissolved oxygen with chironomid-based transfer functions. The results of the biotic proxy were supplemented with a geochemical analysis. The results demonstrated significant changes in the lake community’s structure, its sediment composition, and its redox condition...
Journal of Paleolimnology, 2019
We conducted a paleolimnological study to examine how changes in human activity interacted with c... more We conducted a paleolimnological study to examine how changes in human activity interacted with climate to influence productivity and biodiversity over the past millennium in oligotrophic Lake Atnsjøen, SE Norway. The study included analyses of sediment geochemistry, subfossil diatoms and cladocerans, and macrofossils. Results were compared with the historical record of human activities in the catchment, pollen analysis and paleoclimate inferences from the lake. During the first 750 years of the record (1000 CE-1750 CE), a time of relatively low human activity, lake productivity and biodiversity were strongly related to climate. During the Little Ice Age (1550-1800 CE), lake productivity and diatom diversity were constrained by cold climate. A century of climate warming (1780-1880 CE) initiated an increase in productivity. Accelerated human settlement after 1850 CE, however, had an even stronger impact on productivity, mediated by increased agriculture and/or forestry, which led to greater nutrient loading of the lake. Similarly, diatoms in the lake responded to the rise in temperature, but increasing human activity also had a moderate impact on the diatom community, which displayed weak signs of nutrient enrichment. From 1980-1990 CE onwards, lake productivity declined as a consequence of a recent decrease in human activity and changing land use. The human-induced increase in lake productivity starting ca. 1850 CE propagated through the food web and increased consumer productivity, as reflected by greater accumulation rates of cladocerans, trichopterans and turbellarians. The cladoceran community was likely under top-down control of fish, as indicated by changes in size structure and diversity. Our study showed that increasing human activity during the settlement period had a stronger impact on lake productivity than did climate. Furthermore, the slight human-mediated increase in nutrient loading had different impacts on productivity and biodiversity in the study lake. This study demonstrates that even relatively small changes in human activities in watersheds can have measurable impacts on nutrient-poor lakes.
Palaeogeography, Palaeoclimatology, Palaeoecology, 2019
The authors regret to admit that incorrect information on the TOC flux calculation and TOC flux v... more The authors regret to admit that incorrect information on the TOC flux calculation and TOC flux values as well as figure presenting erroneous results was published in (Zawiska et al., 2017). The incorrect data appeared in Material and Methods part (page 233), in the Results (page 234) and in Fig. 6 (page 237). The corrected information is that: (i) sedimentary TOC flux was calculated using mean sediment accumulation rate for the period studied (0.0133 ± 0.001 g/cm 2 /yr) (ii) minimum TOC flux values of 0.017 mg/cm 2 /yr occurred between 1550 and 1800 CE and maximum value of 0,1 mg/cm 2 /yr was reached in the second half of the 20th century.
Ecological Indicators, 2018
Late glacial and Holocene environmental history of Lake Łukie and its catchment is reconstructed ... more Late glacial and Holocene environmental history of Lake Łukie and its catchment is reconstructed from the lake sediments. This shallow lake is situated in the marshy Polesie region in eastern Poland. Sediments began to accumulate in the lake in the Older Dryas. On the basis of macrofossils, pollen, and Oribatida remains, and with the use of Kohonen's artificial neural network (self-organising map, SOM), six stages (corresponding to subclusters X 1 , X 2 , X 3 in cluster X, and Y 1 , Y 2 , Y 3 in cluster Y) of the lake history were distinguished, and indicator taxa of each stage were identified from the indicator value (IndVal) index. During the transition period corresponding to the border between X and Y, the ecosystem transformed in the broad sense from the protocratic to mesocratic phase in a 5-point scale transformation of the landscape in the glacial-interglacial cycle. All the steps involved in post-glacial history succession during interglacial cycles include changes in climate, soil, and biotic interactions. Indicator taxa for the subsequent SOM subclusters X 1 , X 2 , and X 3 are associated with the first phase of the protocratic glacial-interglacial cycle. The transformation that occurs on the level of cluster Y (subcluster Y 1) is the mesocratic phase (ca. 9000-5000 14 C age BP), which is characterised by high temperatures and development of closed forest (climax forest). Subcluster Y 2 corresponds to the transformation of forest cover during the oligocratic phase (ca. 5000-3000 14 C age BP), which is associated with decreasing forest share and deteriorating soils. Finally, subcluster Y 3 can be associated with the telocratic phase, characterised by the influence of a more oceanic climate (from ca. 2500 14 C age BP) with declining temperatures, higher humidity, and milder seasonal contrasts, which contributed to the development of more open vegetation and infertile soils. This stage also corresponds to an increased human activity and landscape transformation, such as from forests to cornfields and from wetlands to meadows. Interestingly, the currently strictly protected brittle naiad (Najas minor) was present in the lake during the Atlantic, Subboreal, and Subatlantic periods; however, this species is not listed as being part of the present vegetation and may have become extinct relatively recently.
Europa XXI, 2015
The influence of car transport on the sanitary state of the soils is the subject of numerous inve... more The influence of car transport on the sanitary state of the soils is the subject of numerous investigations, carried out in various regions of the world, including Poland. The purpose of the study here presented was to determine the content of the heavy metals (Ni, Pb, Cu, Zn, Cd, and Cr) in the soils of the areas situated along the roads, characterised by different intensities of traffic, different throughput capacities and smoothness of car traffic flow, as well as different road qualities. Investigations have been carried out in various regions of Poland, in the vicinity of the national roads, expressways, as well as motorways. The samples were collected along the transects, located perpendicularly to the road edge, at distances of 1, 3, 5, 10, 20, 50, and 100 metres from the road edge. The analysis of the results obtained allowed for the formulation of the following conclusions: the differences as to the heavy metal content in the soils between the particular segments analysed reach the ratio of over 100 times; the decrease of heavy metal content in the soils follows the distance away from the road towards the open space, and is characterized by a more regular distribution in the case of the areas along the national roads and less regular in the case of areas along the motorways; with similar intensities of traffic, the impact of the motorways on the environment is decidedly lower than of the national roads.
Palaeogeography, Palaeoclimatology, Palaeoecology, 2017
This paper provides a high-resolution temperature reconstruction for the last Millennium from Lak... more This paper provides a high-resolution temperature reconstruction for the last Millennium from Lake Atnsjøen, SE Norway (61°52′31″N, 10°10′37″E). The sedimentary record reveals strong influence of the large-scale global climate patterns on the local climate in southern part of Eastern Norway. We reconstructed mean July air temperature using Chironomidae-based
Wetlands, 2016
Cladocera are one of the most important freshwater biological indicators for a wide range of envi... more Cladocera are one of the most important freshwater biological indicators for a wide range of environmental variables. They show strong responses to several environmental factors (e.g., trophic state, water depth, temperature) and are very sensitive to changes in water pH. The main interest of this study was to evaluate the relationship between subfossil Cladocera community composition and environmental properties of dystrophic lakes (pH, water transparency, conductivity, dissolved oxygen, depth and area). We hypothesize that Cladocera species composition depends on a dystrophication index (HDI); thus, Cladocera assemblages change with the degree of dystrophication. For the study, we selected a group of dystrophic lakes located in Wigry National Park (WNP), NE Poland, where we found subfossil remains of 24 Cladocera species belonging to four families (Chydoridae, Bosminidae, Daphniidae, and Sididae). A non-metric multidimensional scaling (NMDS) was used to elaborate on the similarities among samples in cladoceran-community composition and structure. Statistical analyses showed that Cladocera assemblages in all the studied lakes were similar, and individual Cladocera species respond to the measured environmental parameters (e.g., pH, lake size and depth). Our results suggest that in dystrophic lakes, Cladocera community composition is an emerging characteristic of individual species responses to the environment.
Boreas, 2016
Many German lakes experienced significant water level declines in recent decades that are not ful... more Many German lakes experienced significant water level declines in recent decades that are not fully understood due to the short observation period. At a typical northeastern German groundwater‐fed lake with a complex basin morphology, an acoustic sub‐bottom profile was analysed together with a transect of five sediment cores, which were correlated using multiple proxies (sediment facies, μ‐XRF, macrofossils, subfossil Cladocera). Shifts in the boundary between sand and mud deposition were controlled by lake level changes, and hence, allowed the quantification of an absolute lake level amplitude of ~8 m for the Holocene. This clearly exceeded observed modern fluctuations of 1.3 m (AD 1973–2010). Past lake level changes were traced continuously using the calcium‐record. During high lake levels, massive organic muds were deposited in the deepest lake basin, whereas lower lake levels isolated the sub‐basins and allowed carbonate deposition. During the beginning of the Holocene (>9700...
Deciphering the main processes contributing to lake and landscape evolution in the northern centr... more Deciphering the main processes contributing to lake and landscape evolution in the northern central European lowlands on different temporal scales is one of the main targets of the Virtual Institute of Integrated Climate and Landscape Evolution Analysis (ICLEA) of the Helmholtz Association. In the context of future climatic changes especially the hydrological system is a vulnerable landscape component that showed considerably large changes in the recent past. The analysis of lake sediment archives can help to infer long-term dynamics of regional lake and groundwater levels, although available proxy information needs to be studied carefully, as water level changes are only one trigger. Lake Fürstenseer See (53 • 19'N, 13 • 12'E, lake level in 2009: 63.3 m a.s.l.) formed after the retreat of the Weichselian ice sheet in a subglacial channel in the direct forefront of the Pommerian ice margin. The ∼2 km2 large lake (zmax = 24.5 m) has a (sub-) surficial catchment area of ∼(20) 40 km2 including other smaller lakes and peatlands. In the past, the lake system was artificially dammed for the operation of water mills. Located within the well-drained sandur substrate, the lake levels vary with groundwater levels in response to hydrological and catchment-related groundwater recharge. Detrital matter input from fluvial activity can be excluded. Lake sediment cores at four sites along a transect down to 23 m water depth show distinct sediment facies patterns. Stratigraphic descriptions and non-destructive continuous micro-XRF scanning allowed the differentiation of the main sediment facies, which were microscopically described using thin sections. Quantification of total organic and inorganic matter (TOC, TIC, C/N-composition) and discontinuous macrorest, diatom and Cladocera analysis helped to approach the sedimentation history. Stable isotopes of (delta-180, delta-13C) were used for characterization of carbonates. A high amount of non-reworked terrestrial plant remains from prominent facies shifts were dated with AMS-14C and allowed to link the different cores, assess individual sedimentation rates and to evaluate sediment focusing in the lake. Carbonatic and organic gyttjas are the main sedimentary components related mainly to authigenic production. Sometimes, carbonates show detrital mineral structures and correlations with allochthonous components (K, Ti, Si) that can only be provided by reworking of shore and slope material or in times of intense aeolian transport. Sandy facies dominate only at near-shore, steep sites and form distinct layers at the current sediment limit. A robust statistical analysis considering compositional data constraints allows an objective compilation of indications for lake level change from water depth-related habitat changes and shore erosion. They oppose detrital matter input from aeolian processes in times of anthropogenically-cleared forests. A first lake level reconstruction from the Early Holocene to recent times will be presented and linked to climatic and/or anthropogenic drivers of regional hydrological changes.
Hydrobiologia, 2013
Change in the trophic state of lakes is a topic of primary interest for limnologists and paleolim... more Change in the trophic state of lakes is a topic of primary interest for limnologists and paleolimnologists, but also for governments in many countries. These changes can be the result of the natural evolution of lake ecosystems, but nowadays are most often connected with human activity influencing water bodies. In this article, we reconstruct changes in the lake productivity and trophic state in three dystrophic (humic) lakes located in Northern Poland. Sediments from these lakes, which are part of a national park, were submitted to Cladocera and chemical composition analyses. Currently, the trophic state of these lakes has been described based on the water's chemical composition, and they have been classified as undisturbed ecosystems with a stable trophic state. The main objective of this study was to evaluate whether these lakes have been stable and undisturbed ecosystems during the past centuries and therefore whether they can be classified as natural and pristine. The results of subfossil Cladocera analysis and sedimentary geochemical analysis confirmed the specific nature of studied lakes. However, our results were surprising and showed that during the last 200 years two of the three lakes have undergone distinct trophic changes, while one of them has barely changed at all.
ABSTRACT During the Late Glacial Period environment changes were triggered by climatic oscillatio... more ABSTRACT During the Late Glacial Period environment changes were triggered by climatic oscillations which in turn controlled processes like, for example, permafrost thawing, vegetation development and ground water circulation. These environmental changes are ideally recorded in lake sediments and thus can be reconstructed applying a multi-poxy approach. Here, we present the results from the Trzechowskie paleolake, located in the northern Polish lowlands (eastern part of the Pomeranian Lakeland). The site is situated on the outwash plain of the Wda River, which was formed during the Pomeranian phase of the Vistulian glaciation ca 16,000 14C yrs BP. The depression of the Trzechowskie lake basin formed after melting of a buried ice block during the Allerød (13903±170 cal yrs BP). We reconstructed environmental changes in the Trzechowskie paleolake and its catchment using biotic proxies (macrofossils, pollen, cladocera, diatoms, oribatidae mite) and geochemical proxies (δ18O, δ13C, loss-on-ignition (LOI), CaCO3 content). In addition, we carried out µ-XRF element core scanning. The chronology has been established by means of biostratigraphyAMS14C dating on plant macro remains, varve counting in laminated intervals and the late Allerød Laacher See Tephra isochrone. Our results showed that biogenic accumulation in the lake started during the Bølling. Development of coniferous forest during the Allerød with dominance of Pinus sylvestris lead to leaching of carbonates in the catchment due to low pH increasing the flux of Ca ions into the lake. In consequence calcite precipitating in the lake increased as evidences by increasing CaCO3 contents. Both biotic and physical proxies clearly reflect the rapid decrease in productivity at the onset of the Younger Dryas. We compare the data from the Trzechowskie paleolake with the Meerfelder Maar and Rehwiese lake records based on tephrochronological synchronization using the Laacher See Tephra. This study is a contribution to the Virtual Institute ICLEA (Integrated Climate and Landscape Evolution Analysis) funded by the Helmholtz Association.
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Papers by Izabela Zawiska