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Erik Jeppesen - One of the best experts on this subject based on the ideXlab platform.
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Effects of plant size on the growth of the submersed macrophyte Vallisneria spinulosa S.Z.Yan at different light intensities: implications for Lake Restoration
Hydrobiologia, 2020Co-Authors: Guixiang Yuan, Meihong Zhang, Qian Lou, Dai Taotao, Erik JeppesenAbstract:The growth and reproduction of plants are highly size-dependent and markedly affected by light intensity. Vallisneria spinulosa S.Z.Yan is a common submersed macrophyte and is widely used in current Lake Restoration projects. The size of plants to be used to get optimal Restoration results is not known, however, and may vary with water clarity. In this study, the effects of different plant sizes (large, medium and small, i.e. approximately 2.40 g, 1.01 g and 0.27 g per plant) on the growth and reproduction of V. spinulosa were tested under three light intensities (high, medium, low, i.e. 25%, 6% and 1% of full sunlight, respectively). Both plant size and light intensity were found to be of great significance for plant growth and reproduction. The relative growth rate (RGR) of biomass was higher for small than for large plants at both high and low light, while the absolute growth rate (AGR) of biomass was higher for large-sized plants at medium and high light intensity. Asexual reproduction of V. spinulosa was positively correlated with plant size and more affected by plant size than by light intensity, while sexual reproduction was most affected by light intensity. RGR and AGR of plant height were highest for medium-sized plants at moderate light intensity. Therefore, the size of submersed macrophytes should be considered when using this species in connection with Lake Restoration. Verification of our results under field conditions is needed, though, before firm conclusions can be reached about the optimal plant size of V. spinulosa to be used in Lake Restoration as also other factors like, e.g. periphyton shading and wave actions may play a role.
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effects of Lake Restoration on breeding abundance of globally declining common pochard aythya ferina l
Hydrobiologia, 2019Co-Authors: Anthony D Fox, Martin Sondergaard, Erik Jeppesen, Torben L Lauridsen, Thorsten J S Balsby, Hans Erik Jorgensen, Karsten Fugl, Palle Myssen, Preben ClausenAbstract:Common pochard Aythya ferina are rapidly declining globally, partly due to water quality change at breeding habitats. Lake Restoration at two southern Danish Lakes (external nutrient loading reduction, bream Abramis brama and roach Rutilus rutilus removal and stocking of pike Esox lucius) improved water clarity and submerged macrophyte cover. Nesting pochard on one Lake increased from 2.3 females per annum pre-treatment to 13.9 afterwards and from 22.7 females to 99.6 post-treatment at a second. Numbers fell from 27.7 to 11.3 at a third untreated Lake with consistently high water clarity, but which was colonised and became dominated by holly-leaved naiad Najas marina, which provides no food resources for breeding pochard. Linear modelling (controlling for serial autocorrelation) showed statistically significant effects of annual summer measurements of suspended solids (negative) and Secchi depth (positive) on pochard abundance at both restored Lakes and chlorophyll (negative) at one of those Lakes, but no effects at the third. Breeding pochard numbers also correlated positively with submerged macrophyte cover at one restored Lake with adequate data. Results support the hypothesis that Lake Restoration to improve water quality enhances conditions for locally breeding pochard, as long as restored conditions secure appropriate submerged macrophyte communities for nesting pochard.
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response of submerged macrophyte communities to external and internal Restoration measures in north temperate shallow Lakes
Frontiers in Plant Science, 2018Co-Authors: Sabine Hilt, Elisabeth S. Bakker, Marta Alirangues M Nunez, Irmgard Blindow, Thomas A Davidson, Mikael Gillefalk, Larsanders Hansson, Jan H Janse, Annette B G Janssen, Erik JeppesenAbstract:Submerged macrophytes play a key role in north temperate shallow Lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many Lakes. Considerable efforts have been devoted to shallow Lake Restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, Lake internal Restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting Restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analyzed data on water quality and submerged macrophytes from 49 north temperate shallow Lakes that were in a turbid state and subjected to Restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterized by spring clear-water phases and turbid summers, whereas internal Lake Restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal Lake Restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterized by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative propagules facilitating rapid initial growth and that can complete their life cycle by early summer. Later in the growing season these plants are, according to our simulations, outcompeted by periphyton, leading to late-summer phytoplankton blooms. Internal Lake Restoration measures often coincide with a rapid but transient colonization by hornworts, waterweeds or charophytes. Stable clear-water conditions and a diverse macrophyte flora only occurred decades after external nutrient load reduction or when measures were combined.
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Lake Restoration and management in a climate change perspective an introduction
Water, 2017Co-Authors: Erik Jeppesen, Martin Sondergaard, Zhengwen LiuAbstract:Lakes all around the globe are under severe pressure due to an increasing anthropogenic impact from a growing population in a more developed world. Accordingly, today, many Lakes are highly eutrophic and suffer from severe blooms of often toxic cyanobacteria and may become even more eutrophic in the future unless strong Lake management actions are taken. Recent research has further shown that global warming and subsequent changes in water use will further exacerbate the eutrophication process in Lakes. There is therefore a growing demand for Lake Restoration and insight into sustainable Lake management. The measures to be taken, however, depend on the climate and other local conditions. This special issue addresses Lake Restoration and management with special emphasis on the Restoration of eutrophicated Lakes within a climate change perspective. The papers included collectively highlight that the ongoing climate change affects Lake water quality by (1) changes in external and internal nutrient loading; (2) higher frequency of extreme events (such as hurricanes); (3) temperature‐induced changes in biota, biotic interactions; and (4) water level. Lower nutrient loading is therefore needed in a future warmer world to achieve the same ecological state as today. Several papers discuss Lake Restoration methods within a climate change perspective and show practical results, notably of various attempts of biomanipulation. Finally, some papers discuss the effects of other anthropogenic stressors and their interaction with climate.
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fish community assemblages changed but biomass remained similar after Lake Restoration by biomanipulation in a chinese tropical eutrophic Lake
Hydrobiologia, 2014Co-Authors: Jian Gao, Zhengwen Liu, Erik JeppesenAbstract:While the effects of Lake Restoration by fish manipulation are well-studied in the temperate zone, comparatively little information is available on this issue from tropical Lakes. It may be expected that fish removal leads to faster recovery of the fish stock here than in temperate Lakes due to more frequent and earlier reproduction, which may, in turn, delay positive effects of the Restoration. We studied the community composition, feeding type and abundance of fish in three basins of a tropical shallow Lake: one unrestored basin (UR) and two basins restored by fish manipulation and transplantation of submerged macrophytes. While omni-benthivorous fish dominated the biomass in the restored basins 3 and 5 years after Restoration, planktivores were most abundant in the UR, although total fish biomass remained similar. One-way analyses of similarities based on fish species presence/absence, abundance and biomass data revealed significant differences in fish community composition among the restored basins and UR, and redundancy analyses further indicated that submerged macrophytes were a key driver behind this difference. Our results indicate that active implantation of submerged macrophytes to stabilise the fish community is a tool to consider when planning Lake Restoration by biomanipulation in the tropics.
I De Vicente - One of the best experts on this subject based on the ideXlab platform.
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Ecotoxicity screening of novel phosphorus adsorbents used for Lake Restoration.
Chemosphere, 2019Co-Authors: I. Álvarez-manzaneda, Luis Cruz-pizarro, Anders Baun, I De VicenteAbstract:Abstract Short-term standardized laboratory tests were carried out for evaluating acute and chronic toxicological effects of novel phosphorus (P) adsorbents on Raphidocelis subcapitata (algal growth rate inhibition) and on Daphnia magna (immobilization, with direct and indirect exposure to adsorbents, and uptake-depuration tests). Four P adsorbents were tested: two magnetic (HQ and Fe3O4) and two non magnetic (CFH-12® and Phoslock®). For the case of the algal growth inhibition test, the EC50 was 1.5 and 0.42 g L−1 for HQ and CFH-12®, respectively, and no inhibition patterns were observed neither for Fe3O4 nor for Phoslock®. When organisms were exposed to a direct contact, in the D. magna immobilization test, no statistically significant differences were found in the EC50 values among the four studied adsorbents. The huge difference between direct and indirect contact experiments suggests that toxicity is mainly physically mediated. The uptake-depuration test evidenced a much faster uptake and depuration rates for Phoslock®, which was precisely the adsorbent with the highest particle size. In a realistic worst-case scenario using data from Honda Lake (Almeria, Spain), where Lake Restoration is carried out by a adding a single large dose to bind surplus P in the Lake, the predicted environmental concentrations for all adsorbents were lower than EC50 for all adsorbents and they were found to exceed a provisional limit value for ecotoxicity after a short-term exposure. All in all, since neither accumulation nor longer term effects of P adsorbents in the pelagic phase is expected, this risk may however, on a case-to-case basis, be acceptable.
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Do magnetic phosphorus adsorbents used for Lake Restoration impact on zooplankton community
The Science of the total environment, 2018Co-Authors: I. Álvarez-manzaneda, Francisco Guerrero, A. Del Arco, A. Funes, Luis Cruz-pizarro, I De VicenteAbstract:Abstract Magnetic microparticles (MPs) have been recently proposed as innovative and promising dissolved inorganic phosphorus (DIP) adsorbents. However, before using them in a whole-Lake Restoration project, it is essential to assess their toxicological effects (direct and indirect) on aquatic biota. In the present study we hypothesized that zooplankton community is affected by MPs used for Lake Restoration. To test our hypothesis we designed a microcosms experiment (n = 15) containing Lake water and surface sediment from a hypertrophic Lake. Temporal changes (70 days) on physico-chemical conditions and on zooplankton structure (rotifers, copepods and branchiopods) were monitored under different scenarios. In particular, three different treatments were considered: no addition of MPs (control) and MPs addition (1.4 g MPs L−1) on the surface water layer (T-W) and on the sediment (T-S). After 24 h of contact time, MPs were removed with a magnetic rake. A total of 15 zooplankton species (12 rotifers, 1 branchiopod and 2 copepods) were recorded and a high abundance of zooplankton was registered during the experiment for all treatments. No significant differences (RM-ANOVA test; p > 0.05) in total abundance, species richness and species diversity among treatments were found. The absence of any effect of MPs on zooplankton can be explained because MPs did not significantly alter any of its physico-chemical (e.g. temperature, pH, O2) or biological (e.g. food quantity and quality) drivers. These results confirm the suitability of MPs as a promising tool for removing DIP in eutrophic aquatic ecosystems.
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assessment of toxic effects of magnetic particles used for Lake Restoration on chlorella sp and on brachionus calyciflorus
Chemosphere, 2017Co-Authors: I Alvarezmanzaneda, I De VicenteAbstract:Abstract Laboratory tests, by following standardized Organization for Economic Co-operation and Development (OECD) protocols, were run for evaluating the acute effects of iron magnetic microparticles (MPs), recently proposed for Lake Restoration, on Chlorella sp. (algal growth) and on the rotifer B . calyciflorus (mortality). In addition, the MPs potential indirect effects on rotifer egg bank were assessed by performing hatching rate test with B . calyciflorus cysts in contact with dissolved iron (Tot-Fe dis ). In the algal growth test, no inhibition occurred at the two lowest MPs concentrations (0.01 and 0.05 g l −1 ) which would correspond, considering the adsorption efficiency ratio (Phosphorus: MPs), to P concentrations lower than 0.94 mg P l −1 , much higher than typical concentrations found in natural waters. For higher MPs dose (EC 50 for Chlorella sp. was 0.15 g l −1 ), no nutrient limitations but high turbidity and Tot-Fe dis values cause negative effects on algal growth. For the case of B . calyciflorus , LC 50 was 1.63 g MPs l −1 (corresponding to 30.7 mg P l −1 ). When analyzing Tot-Fe dis effect, the hatching rate of B . calyciflorus cysts was 100% for all treatments. To sum up our results for B . calyciflorus acute and chronic toxicity tests, it is extremely unlikely the mortality of adult organisms in contact with MPs as well as an affectation of the rotifer egg bank. In conclusion, it is expected that MPs addition in a real whole-Lake application cause minor lethal and sublethal effects on both Chlorella sp. and B . calyciflorus .
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Synthesis and characterization of magnetic chitosan microspheres as low-density and low-biotoxicity adsorbents for Lake Restoration
Chemosphere, 2016Co-Authors: A. Funes, J. De Vicente, I De VicenteAbstract:We propose a novel magnetic adsorbent for optimal Phosphorus (P) removal from the upper sediment layers. For this aim, magnetic chitosan microparticles were prepared using a reverse-phase suspension cross-linking technique. The resulting particles and suspensions were characterized using scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, magnetometry, thermogravimetric analysis, electrophoretic mobility and turbidity measurements. The hybrids are multicore particles consisting of well dispersed magnetite nanoparticles (approx. 10% w/w) homogeneously distributed within the biopolymer matrix. These microparticles can be easily separated from the water column and sediment using magnetic field gradients. Their P adsorption capacity is evaluated in batch conditions resulting in a maximum P adsorption capacity of ML = 4.84 mg g-1 at pH = 7. We demonstrate that these particles are excellent candidates to remove P from water column and also P mobile from the upper sediment layers due to two main reasons: they sediment slower and present lower potential toxicity (due to a their larger size) than conventional iron/iron oxide microparticles previously proposed for Lake Restoration.
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Acute and chronic effects of magnetic microparticles potentially used in Lake Restoration on Daphnia magna and Chironomus sp.
Journal of hazardous materials, 2016Co-Authors: I. Álvarez-manzaneda, A. Funes, Eloísa Ramos-rodríguez, Manuel Jesús López-rodríguez, Gema Parra, I De VicenteAbstract:Magnetic microparticles (MPs) have been recently proposed as a new and promising tool for restoring eutrophicated waters. In this study, we analyzed the acute (immobilization) and chronic effects of iron (Fe) MPs on Daphnia magna and on the benthic macroinvertebrate Chironomus sp. In the chronic toxicity tests the offspring production (male and female) in D. magna and the mortality of larvae and pupae, and adult emergence in Chironomus sp. experiments were used as the endpoints. The concentration of MPs that caused 50% of immobilized individuals (EC50) in the acute toxicity test was much higher in D. magna (0.913g MPs l-1) than in Chironomus sp. (0.445g MPs l-1). The results of chronic toxicity tests in D. magna showed that in presence of dissolved Fe (dFe), parthenogenetic reproduction was significantly affected, while no significant effect on mortality of larvae and pupae and on adult emergence was detected in Chironomus sp. test. Taking into account both that long-term exposure is not likely to occur and the regular dose of MPs potentially used in a Restoration plan, we conclude that MPs is a riskless (no toxic effect on planktonic and benthic organisms) and efficient (high P adsorption capacity) tool for Lake Restoration.
Martin Sondergaard - One of the best experts on this subject based on the ideXlab platform.
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effects of Lake Restoration on breeding abundance of globally declining common pochard aythya ferina l
Hydrobiologia, 2019Co-Authors: Anthony D Fox, Martin Sondergaard, Erik Jeppesen, Torben L Lauridsen, Thorsten J S Balsby, Hans Erik Jorgensen, Karsten Fugl, Palle Myssen, Preben ClausenAbstract:Common pochard Aythya ferina are rapidly declining globally, partly due to water quality change at breeding habitats. Lake Restoration at two southern Danish Lakes (external nutrient loading reduction, bream Abramis brama and roach Rutilus rutilus removal and stocking of pike Esox lucius) improved water clarity and submerged macrophyte cover. Nesting pochard on one Lake increased from 2.3 females per annum pre-treatment to 13.9 afterwards and from 22.7 females to 99.6 post-treatment at a second. Numbers fell from 27.7 to 11.3 at a third untreated Lake with consistently high water clarity, but which was colonised and became dominated by holly-leaved naiad Najas marina, which provides no food resources for breeding pochard. Linear modelling (controlling for serial autocorrelation) showed statistically significant effects of annual summer measurements of suspended solids (negative) and Secchi depth (positive) on pochard abundance at both restored Lakes and chlorophyll (negative) at one of those Lakes, but no effects at the third. Breeding pochard numbers also correlated positively with submerged macrophyte cover at one restored Lake with adequate data. Results support the hypothesis that Lake Restoration to improve water quality enhances conditions for locally breeding pochard, as long as restored conditions secure appropriate submerged macrophyte communities for nesting pochard.
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Lake Restoration and management in a climate change perspective an introduction
Water, 2017Co-Authors: Erik Jeppesen, Martin Sondergaard, Zhengwen LiuAbstract:Lakes all around the globe are under severe pressure due to an increasing anthropogenic impact from a growing population in a more developed world. Accordingly, today, many Lakes are highly eutrophic and suffer from severe blooms of often toxic cyanobacteria and may become even more eutrophic in the future unless strong Lake management actions are taken. Recent research has further shown that global warming and subsequent changes in water use will further exacerbate the eutrophication process in Lakes. There is therefore a growing demand for Lake Restoration and insight into sustainable Lake management. The measures to be taken, however, depend on the climate and other local conditions. This special issue addresses Lake Restoration and management with special emphasis on the Restoration of eutrophicated Lakes within a climate change perspective. The papers included collectively highlight that the ongoing climate change affects Lake water quality by (1) changes in external and internal nutrient loading; (2) higher frequency of extreme events (such as hurricanes); (3) temperature‐induced changes in biota, biotic interactions; and (4) water level. Lower nutrient loading is therefore needed in a future warmer world to achieve the same ecological state as today. Several papers discuss Lake Restoration methods within a climate change perspective and show practical results, notably of various attempts of biomanipulation. Finally, some papers discuss the effects of other anthropogenic stressors and their interaction with climate.
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Lake Restoration successes failures and long term effects
Journal of Applied Ecology, 2007Co-Authors: Martin Sondergaard, Erik Jeppesen, Torben L Lauridsen, Christian Skov, Egbert H Van Nes, R M M Roijackers, Eddy H R R Lammens, Rob PortieljeAbstract:1. Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20–30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. 2. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. 3. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4–6 years after the start of fish removal. 4. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. 5. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects ( > 8–10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20-30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4-6 years after the start of fish removal. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects (> 8-10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions.
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Lake Restoration: successes, failures and long‐term effects
Journal of Applied Ecology, 2007Co-Authors: Martin Sondergaard, Erik Jeppesen, Torben L Lauridsen, Christian Skov, Egbert H Van Nes, R M M Roijackers, Eddy H R R Lammens, Rob PortieljeAbstract:1. Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20–30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. 2. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. 3. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4–6 years after the start of fish removal. 4. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. 5. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects ( > 8–10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20-30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4-6 years after the start of fish removal. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects (> 8-10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions.
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Lake Restoration in Denmark
Lakes and Reservoirs: Research and Management, 2000Co-Authors: Martin Sondergaard, Erik Jeppesen, Jens Peder Jensen, Torben L LauridsenAbstract:Lake Restoration in Denmark has involved the use of several different Restoration techniques, all aiming to improve Lake water quality and establishing clear-water conditions. The most frequently used method, now used in more than 20 Lakes, is the reduction of zooplanktivorous and benthivorous fish (especially roach (Rutilus rutilus) and bream (Abramis brama)) with the objective of improving the growth conditions for piscivores, large-sized zooplankton species, benthic algae and submerged macrophytes. Piscivore stocking (mainly Esox lucius (pike)), aiming especially at reducing the abundance of young-of-the-year fish, has been used in more than 10 Lakes and frequently as a supplement to fish removal. Hypolimnetic oxidation, with oxygen and nitrate, has been undertaken in a few stratified Lakes and sediment dredging, with the purpose of diminishing the internal phosphorus loading, has been experimented with in one large, shallow Lake. Submerged macrophyte implantation has been conducted in some of the biomanipulated Lakes to increase macrophyte abundance and distribution. Overall, the results from Lake Restoration projects, in the mainly shallow Danish Lakes, show that external nutrient loading must be reduced to a level below 0.05–0.1 mg P L–1 under equilibrium conditions to gain permanent effects on Lake water quality. By using fish removal, at least 80% of the fish stock should be removed over a period of not more than 1–2 years to obtain a substantial effect on lower trophic levels and to avoid regrowth of the remaining fish stock. Stocking of piscivores requires high densities (>0.1 individuals m–2) if an impact on the plankton level is to be obtained and stocking should be repeated yearly until a stable clear-water state is reached. The experiments with hypolimnetic oxygenation and sediment dredging confirm that internal phosphorus loading can be reduced. Experience from macrophyte implantation experiments indicates that protection against grazing by herbivorous waterfowl may be useful in the early phase of recolonization.
Rob Portielje - One of the best experts on this subject based on the ideXlab platform.
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Lake Restoration successes failures and long term effects
Journal of Applied Ecology, 2007Co-Authors: Martin Sondergaard, Erik Jeppesen, Torben L Lauridsen, Christian Skov, Egbert H Van Nes, R M M Roijackers, Eddy H R R Lammens, Rob PortieljeAbstract:1. Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20–30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. 2. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. 3. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4–6 years after the start of fish removal. 4. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. 5. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects ( > 8–10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20-30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4-6 years after the start of fish removal. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects (> 8-10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions.
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Lake Restoration: successes, failures and long‐term effects
Journal of Applied Ecology, 2007Co-Authors: Martin Sondergaard, Erik Jeppesen, Torben L Lauridsen, Christian Skov, Egbert H Van Nes, R M M Roijackers, Eddy H R R Lammens, Rob PortieljeAbstract:1. Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20–30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. 2. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. 3. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4–6 years after the start of fish removal. 4. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. 5. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects ( > 8–10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20-30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4-6 years after the start of fish removal. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects (> 8-10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions.
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Lake Restoration successes failures and long term effects
Journal of Applied Ecology, 2007Co-Authors: Martin Sondergaard, Erik Jeppesen, Torben L Lauridsen, Christian Skov, Egbert H Van Nes, R M M Roijackers, Eddy H R R Lammens, Rob PortieljeAbstract:1. Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20–30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. 2. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. 3. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4–6 years after the start of fish removal. 4. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. 5. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects ( > 8–10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20-30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4-6 years after the start of fish removal. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects (> 8-10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions.
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Lake Restoration: successes, failures and long‐term effects
Journal of Applied Ecology, 2007Co-Authors: Martin Sondergaard, Erik Jeppesen, Torben L Lauridsen, Christian Skov, Egbert H Van Nes, R M M Roijackers, Eddy H R R Lammens, Rob PortieljeAbstract:1. Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20–30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. 2. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. 3. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4–6 years after the start of fish removal. 4. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. 5. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects ( > 8–10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions Eutrophication constitutes a serious threat to many European Lakes and many approaches have been used during the past 20-30 years to improve Lake water quality. Results from the various Lake Restoration initiatives are diverse and the long-term effects are not well described. In this study we evaluated data from more than 70 Restoration projects conducted mainly in shallow, eutrophic Lakes in Denmark and the Netherlands. Special focus was given to the removal of zooplanktivorous and benthivorous fish, by far the most common internal Lake measure. In more than half of the biomanipulation projects, Secchi depth increased and chlorophyll a decreased to less than 50% within the first few years. In some of the shallow Lakes, total phosphorus and total nitrogen levels decreased considerably, indicating an increased retention or loss by denitrification. The strongest effects seemed to be obtained 4-6 years after the start of fish removal. The long-term effect of Restoration initiatives can only be described for a few Lakes, but data from biomanipulated Lakes indicate a return to a turbid state within 10 years or less in most cases. One of reasons for the lack of long-term effects may be internal phosphorus loading from a mobile pool accumulated in the sediment. Synthesis and applications. Lake Restoration, and in particular fish removal in shallow eutrophic Lakes, has been widely used in Denmark and the Netherlands, where it has had marked effects on Lake water quality in many Lakes. Long-term effects (> 8-10 years) are less obvious and a return to turbid conditions is often seen unless fish removal is repeated. Insufficient external loading reduction, internal phosphorus loading and absence of stable submerged macrophyte communities to stabilize the clear-water state are the most probable causes for this relapse to earlier conditions.
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The central role of fish in Lake Restoration and management
Hydrobiologia, 1999Co-Authors: Eddy H R R LammensAbstract:The central role of fish in Lake Restoration and management has a practical purpose: fish are much easier to manipulate than nutrients, phytoplankton and zooplankton, and therefore they are a relatively easy (additional) instrument in Restoration and management. The management of the fish stock may be a measure of water quality, of fish stock composition or a measure of both and may vary from very drastic removal of planktivorous and benthivorous fish to a more gradual change in the population by continual predator management and less drastic reduction of inedible prey. For Lake Restoration, drastic removal is the most efficient in order to obtain clear water and vegetation and a subsequent fish community adapted to this. Continual management will result in a more gradual change and may be more acceptable to the interest of both fishermen and water quality managers.
