Influence of bacteria and salinity on diatom biogenic silica dissolution in estuarine systems

Dissolution of diatom biogenic silica (bSiO₂) in estuaries and its control by water salinity and bacteria were investigated using the river euryhaline species Cyclotella meneghiniana as a model. Laboratory-controlled bioassays conducted at different salinities with an estuarine bacteria inoculum showed a faster dissolution of diatom bSiO₂ at the lowest salinity where bacteria were the most abundant. However in another experiment, salinity increase clearly enhanced the dissolution of cleaned frustules (organic matter free). The presence of active bacteria might therefore predominate on the effect of salinity for freshly lysed diatoms whereas salinity might rather control dissolution of organic-matter-free frustule remains. Incubation of cultivated diatoms at different protease concentrations revealed that high proteolytic activities had little effect on bSiO₂ dissolution at a 1-month scale in spite of an efficient removal of organic matter from the frustules. Altogether it is hypothesized that bacterial colonization increases bSiO₂ dissolution by creating a microenvironment at the diatom surface with high ectoproteolytic activity but also via the release of metabolic byproducts since the presence of organic matter seems generally to facilitate diatom bSiO₂ dissolution.     

Development of a diatom-based transfer function for lakes and streams severely impacted by secondary salinity in the south-west region of Western Australia

The association of diatom assemblages to salinity was studied in 95 lakes and streams ranging from freshwater to hypersaline in the south-west of Western Australia. The relationship between environmental variables and species composition was explored using canonical correspondence analysis (CCA) and partial CCA. Salinity was shown to account for a significant and independent amount of variation in the diatom data, enabling a transfer function to be developed based on the final dataset, which consisted of 89 sites and 150 diatom taxa. The most successful model was derived using tolerance-downweighted weighted averaging. Summary statistics showed that the transfer function performed very well with a high coefficient of determination and low prediction errors that remained high after the cross-validation method of jackknifing (r _apparent² = 0.97 and r _jackknifed² = 0.89). This suggests that salinity can be accurately predicted using relative abundances of diatoms, and the model can now be applied to paleolimnological reconstructions. However, the transfer function also provides the basis for use in future biomonitoring studies to detect increases in salinity for lakes and streams most at risk, as well as to evaluate the success of remediation measures implemented to secondary salinised systems. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest Editors: J. John & B. Timms Salt Lake Research: Biodiversity and Conservation—Selected papers from the 9th Conference of the International Society for Salt Lake Research     

Effects of salinity gradients on benthic invertebrate and diatom communities in a German lowland river

The Lippe is a lowland river located in the Western part of Germany and has been heavily impacted by coal mining activities ever since. Although mining activities significantly decreased during the last decades, the associated discharge of salt-enriched mine water into the river still poses a persistent threat to the local benthic invertebrate and diatom communities. To analyze the effect of salt pollution on invertebrate and diatom species, biological and chemical data were compiled for this study from a publicly available database. Changes in the community composition due to increased salt concentrations were explored by Non-Metrical-Multidimensional Scaling. Indicator species and salinity thresholds for single species and communities were identified using the method TITAN (Threshold Indicator Taxa Analysis). The method is an analytical approach to detect changes in frequency and abundance of species along an environmental gradient by combining the methods of change point analysis (nCPA) and indicator species analysis. The obtained salinity preferences and individual and community thresholds were compared to the literature and existing salinity classifications. For both diatoms and benthic invertebrates, Non-Metrical-Multidimensional Scaling showed a clear split between samples of high and low salinities. Significant salinity thresholds were determined for 50 invertebrate and 58 diatom species of which 23 respectively 18 species were described as ‘reliable’ indicators according to the specifications given by Baker and King (2010). A majority of salt-tolerant indicator organisms were invasive species. For both organism groups, major changes in community composition were detected at a conductivity value exceeding 900 μS/cm. A reduction of the average salinity to below this threshold may have positive effects on the overall species richness and the persistence of sensitive taxa in the river Lippe. Individual and community thresholds may however be data-dependent to a certain degree and subjected to fluctuations considering the potential interdependencies between salinity and additional physico-chemical and environmental parameters (e.g. water temperature, lime content).     

The Holocene history of vegetation and settlement at the coastal site of Lake Voulkaria in Acarnania, western Greece

A palynological investigation of a Holocene profile from Lake Voulkaria, western Greece, was carried out as a contribution to the environmental history of the coastal area of northwestern Acarnania and the Classical city of Palairos. It shows that deciduous oaks dominated the natural vegetation of the area throughout the Holocene. Until ca. 7000 B.C. Pistacia occurred abundantly, while other evergreen woody taxa were rare. At ca. 6300 B.C. an expansion of Carpinus orientalis/Ostrya can be observed. Around ca. 5300 B.C. spreading of Erica indicates a change to a drier climate and/or first human impact. Since ca. 3500 B.C. an increase of evergreen shrubs now clearly indicates land-use. The foundation of the Classical city of Palairos led to a temporary expansion of Phillyrea maquis. Within this period, molluscs of brackish water indicate the use of the lake as a harbour after the construction of a connection to the sea. The deciduous Quercus woodland recovered when human impact decreased in the area, and lasted until modern times.     

Home range, movement, and site fidelity of translocated northern bobwhite (Colinus virginianus) in southwest Georgia, USA

During 1997 and 1998, we compared home range, movement, and site fidelity characteristics of translocated wild northern bobwhite (Colinus virginianus) to resident birds using radiotelemetry. We captured wild bobwhites (n=74) in southwest Georgia, USA just before the breeding season and relocated them (>1.6 km from capture sites) to sites nearby where previous density estimates revealed that populations were low compared to surrounding areas. Translocated birds were equipped with radiotransmitters and released in groups of 8 to 12. Resident birds (n=166) were also captured and simultaneously monitored via radiotelemetry. We found no difference in home range size (F ₁=0.08, P=0.78), mean daily movements (F ₁=0.04, P=0.84), or distance moved from trap or release sites to arithmetic centers of home ranges (F ₁=1.58, P=0.21) between translocated and resident bobwhites. These results suggest that translocating wild bobwhites over relatively short distances into suitable habitat does not negatively influence bobwhite movement and renders site fidelity as reasonable. Therefore, translocation of wild bobwhites before breeding season can result in enhanced numbers of adult breeders in a target location and potentially augments fall populations via reproductive yield.     

Nest site selection and nesting success of five species of passerines in a South American open Prosopis woodland

I analyzed nest site preferences and whether these preferences were linked to nest success of five bird species breeding in an arid area of southern South America. Most nests (90%) were located in three plant species (Geoffroea decorticans, Capparis atamisquea, and Atriplex lampa). Serpophaga griseiceps, Poospiza ornata, and P. torquata nested in plants with size significantly different from randomly selected plants. At the mesohabitat scale (i.e., habitat patch surrounding the nest), four species showed clear differences from random patches within the general habitat, and the remaining species (Saltatricula multicolor) showed a non-significant trend. The daily survival rate of S. griseiceps nests placed in the preferred plant species (i.e., G. decorticans) was lower than those in the other nest-plants. In the other four bird species, nest survival did not differ between preferred and other plants used for nesting. At the scale of microhabitat (i.e., plant size and location of the nest inside the plant), no significant differences were detected between unsuccessful and successful nests. Similarly, unsuccessful nest patches did not differ significantly in habitat features from those that were successful. High nest predation rates found in this habitat (around 85% for the total assemblage) and a relatively high diversity of predators (and of predation tactics) appear to impede the presence of safe sites for nesting (i.e., there are trade-offs between avoidance strategies).     

Late holocene human impact on two coastal environments in New South Wales,Australia: a comparison of Aboriginal and European impacts

There are few historical analyses quantifying impacts of human activity in Australia. This paper compares vegetation change, fire regime, erosion and eutrophication rates between the European period and the recent prehistoric past in two lake systems on the south coast of New South Wales. The variance in pollen abundance and hence species population changes increased markedly in the historical period, especially amongst understorey taxa, and this could be related to changes in the local fire regimes and to the effects of grazing. Local fire activity decreased from the prehistorical period at both sites. Erosion rates increased in the historical period and both organic and inorganic components were deposited in the lakes. Erosion episodes could be related to fire during some periods but are clearly controlled by forest disturbance and land-use at other periods. The trophic status of the lakes was increasing from before European settlement but accelerated in the recent past. This was in part due to the increased erosion rates and in part due to fertiliser application. The results suggest that lower rates of erosional and eutrophic change occur in catchments with basaltic than with Holocene sand substrata.     

The relationship between fish species richness, abundance and habitat complexity in a range of shallow tropical marine habitats

A simple habitat assessment score (HAS) was designed to assess habitat complexity across several different shallow tropical marine habitats including sandy patches, algal beds, seagrass beds and reefs. It measured rugosity, variety of growth forms, height, refuge size categories, percentage live cover and percentage hard substratum. Multiple regression models using HAS variables as predictors accounted for 71 and 22% of the variation in observed species richness and total fish abundance respectively. The two most important predictors of observed species richness were rugosity and variety of growth forms, while height was the most important predictor of total fish abundance. The HAS method worked consistently across a variety of habitat types and the complexity map closely mirrored the map of observed species richness, reflecting the patchy habitat mosaic of shallow tropical marine areas. Stations at the mouth of an enclosed lagoon, however, had a higher number of species than might have been expected judging from the habitat complexity scores. It is possible that this was linked to the preferential settling of pelagic fish larvae in this area as tidal water exchanges between the bay and the reef were funnelled through one small gap. This study highlights the need for fish biodiversity studies to take habitat complexity into account.     

Vegetation development at a mountain settlement site in the Swedish Scandes during the late Holocene: palaeoecological evidence of human-induced deforestation

A palaeoecological study was conducted close to the forest limit in the northern Scandinavian mountain range. The aim was to elucidate the degree to which human impact has affected the vegetation at Hiednikvalta, a Stállo settlement site. Stállo settlements consist of round hut foundations that have a hearth in the middle and are surrounded by a low turf wall. They were probably established by Sámi people using the mountain areas for hunting and/or reindeer herding. In order to separate the effects of humans and climate on the vegetation, a reference area approach was adopted, i.e. the vegetation development at the Stállo settlement site Hiednikvalta was compared with the vegetation development in a forested reference area Avvuhatjåhkkå, at the same altitude as Hiednikvalta but with no archaeological remains of settlements. Peat stratigraphies were retrieved at the two sites and pollen analysis, loss-on-ignition (LOI), pollen accumulation rates (PAR), macrofossil analysis and Betula pollen size statistics were all examined. The results indicate that Hiednikvalta was forested with Betula trees prior to the Stállo settlement period, which occurred between the eighth and thirteenth centuries. Human activities resulted in a decrease in tree cover at the site, as found in a previous study at Adamvalta, another Stállo settlement site in the region. However, the magnitude of vegetation change, and the post-Stállo vegetation development differed between the two areas, suggesting that site-specific factors are important. The use of reference areas in palynological studies is also discussed.     

The cost of dispersal: predation as a function of movement and site familiarity in ruffed grouse

Ecologists often assume that dispersing individuals experienceincreased predation risk owing to increased exposure to predatorswhile moving. To test the hypothesis that predation risk isa function of movement distance or rate of movement, we usedradio-telemetry data collected from 193 ruffed grouse (Bonasaumbellus) during 1996–1999 in southeastern Ohio. Cox'sproportional hazards model was used to examine whether the riskof predation was affected by the rate of movement and site familiarity.We found evidence indicating that increased movement rates mayincrease the risk of predation for adult birds but not juveniles.We also found juvenile and adult birds inhabiting unfamiliarspace were consistently at a much higher risk of predation (threeto 7.5 times greater) than those in familiar space. Our resultsindicate that although movement itself may have some effecton the risk of being preyed upon, moving through unfamiliarspace has a much greater effect on risk for ruffed grouse. Thissupports the hypothesis that increased predation risk may bean important cost of dispersal for birds.     

Numerical and functional response of predators to a long-term decline in mammalian prey at a semi-arid Neotropical site

Summary Occurrence and diet of ten carnivorous predators (four falconiforms, four owls, and two foxes), and population levels of their mammalian prey, were monitored over 45 months at a semi-arid site in north-central Chile. Early in this period, small mammals irrupted and then declined markedly to a density 7% of that at peak. All four falconiforms (Buteo polyosoma, Falco sparverius, Geranoaetus melanoleucus, Parabuteo unicinctus) and one owl (Tyto alba) responded numerically to the decline in mammalian prey by virtually abandoning the study site. The three other owls (Athene cunicularia, Bubo virginianus, Glaucidium nanum) and the two foxes (Pseudalopex culpaeus and P. griseus) remained. With few exceptions, throughout the study predators maintained species-specific preferences among small mammal species regardless of the absolute and proportional abundance of these prev. At no time did the two prey species most responsible for the irruption (the rodents Phyllotis darwini and Akodon olivaceus) occur in predators' diets out of proportion to their estimated relative abundance in the field. Predators were clearly unable to prevent the irruption from occurring. Given the absence of a clear functional response to the most irruptive species, predators seemed unlikely to have been responsible for the observed crash. At present, however, predators may be prolonging the crash and delaying the return of small-mammal populations to typical densities.     

Effects of position, understorey vegetation and coarse woody debris on tree regeneration in two environmentally contrasting forests of north-western Patagonia: a manipulative approach

Aim To investigate the differential effects of position within gaps, coarse woody debris and understorey cover on tree seedling survival in canopy gaps in two old‐growth Nothofagus pumilio (Poepp. & Endl.) Krasser forests and the response of this species to gaps in two forests located at opposite extremes of a steep rainfall gradient. Location Nahuel Huapi National Park, at 41° S in north‐western Patagonia, Argentina. Methods In both study sites, seedlings were transplanted to experimental plots in gaps in three different positions, with two types of substrate (coarse woody debris or forest floor), and with and without removal of understorey vegetation. Survival of seedlings was monitored during two growing seasons. Soil moisture and direct solar radiation were measured once in mid‐summer. Seedling aerial biomass was estimated at the end of the experiment. Results Mid‐summer soil water potential was lowest in the centre of gaps, in plots where the understorey had been removed, and highest at the northern edges of gaps. Direct incoming radiation was highest in gap centres and southern edges, and lowest at northern edges. Seedling mortality was highest in gap centres, in both sites. Coarse woody debris had a positive effect on seedling survival during summer in the mesic forest and during winter in the xeric forest. The removal of understorey cover had negative effects in gap centres during summer. Seedling final aerial biomass was positively affected by understorey removal and by soil substrate in both sites. In the dry forest gaps, seedling growth was highest in northern edges, whereas it was highest in gap centres in the mesic forest. Overall growth was positively related to survival in the xeric forest, and negatively related in the mesic forest. Main conclusions Survival and growth were facilitated by the shade of gap‐surrounding trees only in the xeric forest. Understorey vegetation of both forests facilitated seedling survival in exposed microsites but competed with seedling growth. Nurse logs were an important substrate for seedling establishment in both forests; however, causes of this pattern differed between forests. Water availability positively controls seedling survival and growth in the xeric forest while in the mesic forest, survival and growth are differentially controlled by water and light availability, respectively. These two contrasting old‐growth forests, separated by a relatively short distance along a steep rainfall gradient, had different yet unexpected microenvironmental controls on N. pumilio seedling survival and growth. These results underscore the importance of defining microscale limiting factors of tree recruitment in the context of large‐scale spatial variation in resources.     

Vegetation and fire history of a Chinese site in southern tropical Xishuangbanna derived from phytolith and charcoal records from Holocene sediments

Aim The aims of this paper are to reconstruct the vegetation and fire history over the past 2000 years in a well‐preserved rain‐forest area, to understand interactions between climate, fire, and vegetation, and to predict how rain forest responds to global warming and increased intensity of human activity. Location Xishuangbanna, south‐west China, 21–22° N, 101–102° E. Methods Phytolith (plant opal silica bodies) morphotypes, assemblages, and indices were used to reconstruct palaeovegetation and palaeoclimate changes in detail. Micro‐charcoal particles found in phytolith slides, together with burnt phytoliths and highly weathered bulliform cells, were employed to reconstruct a record of past fire occurrence. A survey of field sediments, lithology, and ¹⁴C dating were also employed. Results Phytoliths were divided into 11 groups and classified into 33 well‐described morphotypes according to their shape under light microscopy and their presumed anatomical origins and ecological significance. The phytolith assemblages were divided into six significant zones that reveal a complete history of vegetation changes corresponding to climate variation and fire occurrence. Phytolith assemblages and indices show that the palaeoclimate in the study area is characterized by the alternation of warm–wet and cool–dry conditions. Phytolith and charcoal records reveal that 12 fire episodes occurred. Comparison of burnt phytoliths with an aridity index (Iph) shows that fire episodes have a strong relationship with drought events. Main conclusions Our results indicate that fire occurrence in the tropical rain forest of Xishuangbanna is predominantly under the control of natural climate variability (drought events). Nearly every fire episode is coupled with a climatic event and has triggered vegetation composition changes marked by a pronounced expansion of grasses. This indicates that drought interacts with fire to exert a strong influence on the ecological dynamics of the rain forest. However, the impact of human activity in recent centuries is also significant. Our results are important for understanding the interactions between climate, fire, and vegetation, and for predicting how rain forest responds to global warming and increased human activity.     

Macroinfauna community structure and biochemical composition of sedimentary organic matter along a gradient of wave exposure in sandy beaches (NW Spain)

Six sandy beaches on the North West coast of Spain, exposed to different wave action, were sampled in order to study the macroinfauna community and the biopolymeric fraction (proteins, lipids and carbohydrates) of sedimentary organic matter. According to McLachlan’s rating system (1980), three of them were classified as sheltered and the other three as exposed beaches. Sampling was carried out during August 2004 at three tidal levels: high, medium and low. Macroinfauna community and organic matter concentrations were found to be significantly different when sheltered and exposed beaches were compared. Macroinfauna diversity (H′), abundances and biomass became increasingly enriched along a gradient from exposed to sheltered beaches. Macroinfauna mean abundance was found higher in sheltered (ranked from 1535 ± 358 to 15062 ± 5771 ind m⁻²) than in exposed beaches (from 150 ± 41 to 5518 ± 1986 ind m⁻²). Macroinfauna biomass ranged from 3.2 to 14.7 g m⁻² and species richness from 25 to 27 in sheltered localities; while in exposed beaches, biomass ranged from 0.2 to 2.3 g m⁻² and the number of species from 5 to 14. The biopolymeric carbon concentration (BPC) was significantly higher in sheltered (from 84.7 ± 44.7 to 163.3 ± 34.8) than in exposed (from 30.3 ± 7.5 to 78.7 ± 12.3) beaches. The low hydrodynamic conditions of sheltered beaches favoured the settlement of organic rich fine sediments, being supported by the higher protein to carbohydrate ratio found in the exposed (from 23.5 ± 0.9 to 32.7 ± 4.4), rather than in the sheltered localities (from 6.2 ± 0.7 to 13.6). Mean macroinfauna abundances were higher at medium and low tidal levels in both sheltered and exposed beaches. Crustacea was found to be the main group inhabiting the upper part of both types of beaches, dominating all tidal levels of exposed sandy beaches. Mollusca and Polychaeta groups were dominant in sheltered beaches at the medium and lower levels. There was a significant negative relationship between the BPC and the beach face slope; thus, BPC decreased as the intertidal slope increased. It seems that exposed sandy beaches are mainly physically controlled, whereas hospitable sheltered beaches let other factors, such as biochemical compounds, enrich the benthic fauna scenery. Electronic Supplementary Material  Supplementary material is available in the online version of this article at and is accessible for authorized users Handling editors: K. Martens     

Wood properties of juvenile Pinus radiata growing in the presence and absence of competing understorey vegetation at a dryland site

Pinus radiata D. Don trees were grown in the presence and absence of the woody weed broom (Cytisus scoparius L.) on a dryland site for 2 years to determine the effects of competition from weeds on wood properties in juvenile trees. Wood property measurements made on cross-sections from the bark to the pith were scaled to convert results from distance to a time basis using sigmoidal equations fitted to monthly measurements of tree diameter. When averaged across the 2 years, the presence of the weeds significantly increased wood density (+11%), wall thickness (+6%) and modulus of elasticity (MOE_SS, +93%), and significantly reduced microfibril angle (MFA, –21%) and radial diameter (–8%). Radial growth rate was significantly correlated to wood density, and this relationship held across both treatment and age. At the seasonal scale, there was close correspondence between changes in MFA and growth rate. Ring width was significantly related to both MFA and MOE_SS at the annual scale. Although both of these relationships held across treatments, year significantly influenced the value of coefficients in the relationships. The results highlight the direct effects of the presence of weeds on wood properties and the need to consider silvicultural treatments appropriate for balancing gains in productivity with losses in wood quality for timber production.     

Life history costs and benefits of encephalization: a comparative test using data from long-term studies of primates in the wild

The correlation between brain size and life history has been investigated in many previous studies, and several viable explanations have been proposed. However, the results of these studies are often at odds, causing uncertainties about whether these two character complexes underwent correlated evolution. These disparities could arise from the mixture of wild and captive values in the datasets, potentially obscuring real relationships, and from differences in the methods of controlling for phylogenetic non independence of species values. This paper seeks to resolve these difficulties by (1) proposing an overarching hypothesis that encompasses many of the previously proposed hypotheses, and (2) testing the predictions of this hypothesis using rigorously compiled data and utilizing multiple methods of analysis. We hypothesize that the adaptive benefit of increased encephalization is an increase in reproductive lifespan or efficiency, which must be sufficient to outweigh the costs due to growing and maturing the larger brain. These costs and benefits are directly reflected in the length of life history stages. We tested this hypothesis on a wide range of primate species. Our results demonstrate that encephalization is significantly correlated with prolongation of all stages of developmental life history except the lactational period, and is significantly correlated with an extension of the reproductive lifespan. These results support the contention that the link between brain size and life history is caused by a balance between the costs of growing a brain and the survival benefits the brain provides. Thus, our results suggest that the evolution of prolonged life history during human evolution is caused by increased encephalization.     

Short and long-term effects of unguided internet-based cognitive behavioral therapy for chronic insomnia in morning and evening persons: a post-hoc analysis

ABSTRACT

A post-hoc analysis comparing morning and evening persons with insomnia on sleep and mental health characteristics was conducted in order to investigate whether an Internet-based cognitive behavioral therapy for insomnia (ICBTi) was effective both for morning and evening persons. Adult patients (N = 178, mean age = 44.8, 67% females) with insomnia were randomized to either ICBTi (N = 92; morning persons = 41; evening persons = 51) or a web-based patient education condition (N = 86; morning persons = 44; evening persons = 42). All patients were assessed with sleep diaries, the Insomnia Severity Index (ISI), the Bergen Insomnia Scale (BIS), the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS-16), the Hospital Anxiety and Depression Scale (HADS) and the Chalder Fatigue Scale (CFQ). Patients were characterized as morning or evening persons based on a median split on the Horne-Östberg Morningness Eveningness Questionnaire. Short and long-term effects of treatment were examined with mixed-model repeated-measures analyses. Morning and evening persons did not differ in terms of age, gender or educational status. At baseline, morning persons had more wake time after sleep onset (d= 0.54, p < .001) and more early morning awakening (d= 0.38, p < .05) compared to evening persons, while evening persons reported longer sleep onset latency (d= 0.60, p < .001), more time in bed (d= 0.56, p < .001), longer total sleep time (d= 0.45, p < .01), more fatigue (d= 0.31, p < .05) and more dysfunctional beliefs and attitudes about sleep (d= 0.47, p < .01). Despite these differences at baseline, both morning and evening persons receiving ICBTi benefitted more across most measures compared to morning and evening persons who received patient education. For morning persons in the ICBTi group, ISI scores were reduced from 17.3 at baseline to 8.8 (d_pre-post = 2.48, p < .001) at post-assessment, and to 10.0 at 18-month follow up (d_pre-post18m = 2.13, p < .001). Comparable results were found for evening persons in the ICBTi group, with a reduction in ISI scores from 17.4 at baseline to 8.6 (d_pre-post = 2.24, p < .001) at post-assessment, and to 8.7 at 18-month follow up (d_pre-post18m = 2.19, p < .001). Similar results were found on the BIS, DBAS, HADS, CFQ and sleep diary data. Despite different insomnia symptomatology between the two groups, the current study suggests that ICBTi is effective across scores on the morningness-eveningness dimension. The study was pre-registered at: ClinicalTrials.gov Identifier: NCT02261272.     

Multiproxy study of anthropogenic and climatic changes in the last two millennia from a small mire in central Poland

The Żabieniec kettle hole is the first peatland in central Poland analyzed quantitatively with four biotic proxies (plant macrofossils, pollen, testate amoebae and chironomids) to reconstruct the past environmental change. Palaeoecological data were supported by historical and archaeological records. We focused on autogenic vegetation change and human impact in relation to climatic effects. The aims of our study were (a) to describe the development history of the mire during the last 2,000 years, (b) to date and reconstruct the anthropogenic land-use changes and (c) to discuss a possible climatic signal in the peat archive. The combination of proxies revealed dramatic shifts that took place in the peatland since the Roman Period. Żabieniec was a very wet telmatic habitat until ca. AD 600. Then, the water table declined, and the site transformed into a Sphagnum-dominated mire. This dry shift took place mainly during the Early Medieval Period. Human impact was gradually increasing, and it was particularly emphasized by deforestation since AD 1250 (beginning of the Late Medieval Period). Consequently, surface run-off and aeolian transport from the exposed soils caused the eutrophication of the mire. Furthermore, chironomids and testate amoebae reveal the beginning of a wet shift ca. AD 1350. Openness considerably increased in the Late Medieval and the Modern Periods. The highest water table during the last 1,000 years was recorded between AD 1500 and 1800. This wet event is connected with deforestation, but it could be also associated with the Little Ice Age. Our study shows plant succession in the Żabieniec peatland, which can be explained with the recent landscape transformation. However, such changes are also possibly linked with the major climatic episodes during the last two millennia, such as the Medieval Warm Period and the Little Ice Age. Guest editors: K. Buczkó, J. Korponai, J. Padisák & S. W. Starratt Palaeolimnological Proxies as Tools of Environmental Reconstruction in Fresh Water