Long-Term Consequences of Water Pumping on the Ecosystem Functioning of Lake Sekšu, Latvia

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-Isoetes 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 conditions due to increased eutrophication, water level fluctuations, and erosion. The additional nutrient load, particularly phosphorus, increased the abundance of planktonic eutrophic-hypereutrophic diatoms, the lake water's transparency decreased, and hypolimnetic anoxia occurred. Cladocera, Chironomidae, and diatoms species indicated a community shift towards eutrophy, while the low trophy species were suppressed or disappeared.Peer reviewe

Long-Term Consequences of Water Pumping on the Ecosystem Functioning of Lake Sekšu, Latvia

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 conditions due to increased eutrophication, water level fluctuations, and erosion. The additional nutrient load, particularly phosphorus, increased the abundance of planktonic eutrophic–hypereutrophic diatoms, the lake water’s transparency decreased, and hypolimnetic anoxia occurred. Cladocera, Chironomidae, and diatoms species indicated a community shift towards eutrophy, while the low trophy species were suppressed or disappeared

Long-Term Consequences of Water Pumping on the Ecosystem Functioning of Lake Sekšu, Latvia

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 conditions due to increased eutrophication, water level fluctuations, and erosion. The additional nutrient load, particularly phosphorus, increased the abundance of planktonic eutrophic–hypereutrophic diatoms, the lake water’s transparency decreased, and hypolimnetic anoxia occurred. Cladocera, Chironomidae, and diatoms species indicated a community shift towards eutrophy, while the low trophy species were suppressed or disappeared

The effects of PLA biodegradable and polypropylene nonwoven crop mulches on selected components of tomato grown in the field

The results of two years (2010-2011) of field studies using two types of nonwoven mulches (one biodegradable, polylactic acid PLA 54 g m-2, and traditional polypropylene PP 50 g m-2) on the yield and quality of tomato are presented. Seeds of tomato (‘Mundi’ F1) were sown in a greenhouse, in containers filled with perlite and sand, and then the plants at the cotyledon stage were replanted in multipot trays filled with substrate for vegetable plants. In the last week of May, seedlings were planted on mulches in the field at a spacing of 50 × 100 cm. The mulch was maintained throughout the growing season. A plot that remained unmulched served as the control. Tomatoes were harvested once a week. The fruits were evaluated for L-ascorbic acid, dry matter, soluble sugars and nitrate content. In 2011, the analysis of the plant material showed that the concentration of L-ascorbic acid was about 23% higher in the tomato fruits harvested from plants grown on biodegradable PLA 61 g m-2 mulch in comparison to the control. A similar effect was demonstrated for the soluble sugar concentration in 2011 for both types of nonwovens

The effect of biodegradable direct covers on the root development, yield and quality of cucumber

Przedstawiono wyniki trzyletnich (2009-2011) badań z wykorzystaniem do bezpośredniego osłaniania roślin ogórka dwóch włóknin biodegradowalnych (IBWCH 75 g m-2 i P LA 5 4 g m-2). Nasiona ogórka partenokarpicznego ‘Mirabelle’ F1 wysiano bezpośrednio do gruntu na początku maja/czerwca i jednocześnie przykryto włókninami biodegradowalnymi. Jako kontrolę przyjęto rośliny nieosłonięte. Osłony utrzymywano do momentu pojawienia się pierwszych kwiatów. Owoce ogórka zbierano co 3 dni przez okres 5-6 tygodni. W laboratorium w owocach oznaczano zawartość suchej masy, cukrów rozpuszczalnych oraz jonów azotanowych. Po wykonaniu ostatniego zbioru owoców wykopano całe roślin ogórka z gleby - wraz z systemem korzeniowym, który następnie został poddany analizom pod względem: masy, całkowitej powierzchni, całkowitej długości oraz przeciętnej średnicy rozgałęzienia. Doświadczenia wykazały, że zastosowanie osłon (niezależnie od rodzaju polimeru, z którego zostały wykonane) spowodowało wzrost wielkości plonu handlowego owoców ogórka w 2009 i 2010 roku, nie wykazano takiego w pływu w ostatnim roku doświadczeń (2011). W 2011 roku owoce ogórka zebrane z obiektów osłoniętych wykazały większą zawartość cukrów rozpuszczalnych, suchej masy w porównaniu z kontrolą. Zastosowanie osłon nie wpłynęło na oceniane parametry rozwoju systemu korzeniowego

Interpretative machine learning as a key in recognizing the variability of lakes trophy patterns

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 – Ptot. 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 en- compass watershed geometry geology and land use. Our method involves building a regression model, creating an ex- plainer, 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 variable possible. The study reveals that there are five clusters where the concentration of Ptot is shaped similarly. We compared our method with other numerical analyses and showed that it provides new information on the catchment area and lake trophy relationship

Historical human impact on Productivity and biodiversity in a subalpine oligotrophic lake in Scandinavia

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 (1000–1750 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 to 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.acceptedVersio

Climate variability and lake ecosystem responses in western Scandinavia (Norway) during the last Millennium

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 transfer function and fossil Chironomidae assemblages. The reconstruction was supported by a selection of climate-sensitive geochemical and paleoecological sedimentary proxies of terrestrial and aquatic origin, including Cladocera, pollen and macrofossils. Presented results revealed that summer temperatures were 1–2 °C warmer than the mean Millennial temperatures during the 11th, 13th, 15th and 20th centuries and 1–2 °C lower during the 12th, 14th, 17th–18th centuries. A persistent cold period, the Little Ice Age (LIA), occurred between 1550 and 1800 CE, was interrupted by a short warming at 1650 CE. The recognized regional climate fluctuations during the last Millennium affected the lake and its catchment, of which the strongest impact was caused by the LIA cooling. During the LIA the catchment vegetation was impacted by climate deterioration and the lake productivity reached its lowest level during the last Millennium. The current temperature reconstruction is in agreement with a previous continental scale temperature reconstruction for Europe. From obtained results it emerges that during the LIA the climate of western Scandinavia has been dictated by the atmospheric patterns originating from the North Atlantic.peerReviewe

Long-Term Consequences of Water Pumping on the Ecosystem Functioning of Lake Sekšu, Latvia

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 conditions due to increased eutrophication, water level fluctuations, and erosion. The additional nutrient load, particularly phosphorus, increased the abundance of planktonic eutrophic–hypereutrophic diatoms, the lake water’s transparency decreased, and hypolimnetic anoxia occurred. Cladocera, Chironomidae, and diatoms species indicated a community shift towards eutrophy, while the low trophy species were suppressed or disappeared. eutrophication; water level fluctuation; multi-proxy approach; Cladocera; Chironomidae; diatoms; Northern Europ