Lake Restoration Tool Research Articles

What drives growth responses of nitrogen and phosphorus (co-)limited primary producer communities?

The growth of autotroph communities is frequently (co-)limited by essential nutrients such as nitrogen (N) and phosphorus (P). Several mechanisms have been proposed to explain the observed co-limitation patterns at different levels of biological organization, especially at the biochemical level for individual species. When considering communities, the presence of different species and functional groups with contrasting physiologies and nutrient requirements leads to a more difficult understanding of the mechanisms involved in nutrient (co-)limitation. To investigate what drives co-limitation patterns and possible underlying mechanisms based on biomass responses in autotroph communities, we grew phytoplankton communities differing in species composition in experimental microcosms on three N:P ratios to impose different limiting conditions. Afterwards, N, P, both, or none were factorially supplied to the communities to test which nutrients were limiting growth. We measured the biovolume of single species in the communities to assess how they responded to nutrient additions and compared it to the response of the overall community biovolume. The types of nutrient (co-)limitation identified, i.e. the factorial limitation scenarios for community biomass were single N limitation or simultaneous co-limitation by N and P, and were strongly driven by the dominant species. The phytoplankton species in the communities responded differently to the nutrient addition treatments, i.e. they showed contrasting limitation outcomes and therefore likely different nutrient requirements. Our experiment indicates that phylogenetically distantly-related phytoplankton species grown in a community can have different resource use efficiencies and thus can be limited by different nutrients. We suggest that the dominance of species or groups with similar traits in nutrient requirements and acquisition is one of the leading mechanisms that determines the biomass pattern of nutrient (co-)limitation observed at the community level. This work also highlights the potential of predicting community growth limitation outcomes based on knowledge of nutrient use efficiencies of one or few dominant species, which can be a suitable tool for lake restoration and oligotrophication efforts.

A web-based numerical model for sustainable management of Lake Batur, Bali: Preliminary results

Lake Batur is one of The National Priority Lakes according to President Regulation Number 60/2021 with the target of restoring water quality through the pollution control program for floating net fishery (FNF), agriculture, and other anthropogenic sources around the watershed. The regulation also states several internal measures designed to restore the lake’s water quality. Unfortunately, detailed information on pollution control priorities, the amount that must be controlled for water quality improvements to be visible, and the effectiveness of internal restoration efforts have yet to be obtained. This can hinder the lake restoration process and, furthermore, its sustainable management. This study aimed to develop a web-based numerical model as an open-source web-service for guiding restoration in Lake Batur. It is accessible via the interactive graphical user interface (GUI) running in a standard web browser and includes tools of varying complexity. The platform provides the user with features to set up some parameters, run and analyze the numerical water quality, and the possibility to set up, run and compare various lake management scenarios. The preliminary results show that the model was able to represent existing daily water quality dynamics. Hopefully, the model can be used as a tool for lake restoration and as a part of sustainable lake management.

Application of floating treatment wetlands in a highly eutrophic lake, Indonesia: a new tool for lake restoration and provision of microhabitat

Two sets of floating treatment wetlands (FTWs) have been evaluated as a tool for lake restoration and microhabitat provision for aquatic biota in a highly eutrophic and polymictic Lake Maninjau, Indonesia. Each FTW system consisted of 14 units square floating frame built using PVC pipes and palm sugar fibres as material mat transplanted onto net. All units of FTW were planted with different vegetation composition arrangement then placed inside the square metal frame attached on buoyant plastic drums to support the FTWs against the wave. The plants used in this study were Canna variegata, Vetiveria zizanioides, Cyperus papyrus, Echinodorus polaefolius and Limnocharis flava. FTWs were evaluated for 7 months for nutrient removal efficiency and other water quality indicators. Despite unstable lake conditions accompanied by strong waves and lake mixing, the cage and the PVC frame of FTWs applied remained intact and providing the buoyancy to support the plant growth. The plants in FTWs grew and adapted well in the turbulence water and even in the hypoxic conditions. Improvement of lake water quality in the FTWs area may be small but the accumulated nutrients content in the plant shoots suggests high removal of nutrients. In total by the end of observation, one FTWs system could remove > 100 g N and > 7 g P from the lake water. During field observation, important local fish and diverse wildlife activities were recorded including inhabiting, foraging, breeding, nursing and resting in the FTWs. Our study suggests that FTWs can be a promising tool for lake restoration to improve lake water quality and for microhabitat provision.

Application of Effective Microorganisms Technology as a lake restoration tool - A case study of Muchawka Reservoir

Application of Effective Microorganisms Technology as a lake restoration tool - A case study of Muchawka Reservoir

Acute and chronic effects of magnetic microparticles potentially used in lake restoration on Daphnia magna and Chironomus sp.

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.

Magnetic microparticles as a new tool for lake restoration: A microcosm experiment for evaluating the impact on phosphorus fluxes and sedimentary phosphorus pools

In the last decades, magnetic particles (MPs) as adsorbents have gained special attention due to their high adsorption capacity and the possibility of recovering them by applying a magnetic separation gradient. For the first time MPs have been tested as P adsorbents in a microcosm experiment in a context of lake restoration. MPs were added to sediment cores from a hypertrophic lake, at Fe:PMobile molar ratio of 285:1 and 560:1 under both, oxic and anoxic conditions. We have found that, under anoxic conditions (anoxic), MPs are able to reduce P release rate from the sediment to the overlying water and to reduce sedimentary PMobile concentration (a 22–25% reduction within 0–4 cm depth compared to controls). Under oxic conditions, the addition of MPs do not affect P fluxes across the sediment and water interface since the lake sediment is naturally rich in iron oxides. However a measured reduction in sedimentary PMobile concentration (12–16% reduction in 0–10 cm depth) contributes to a potential reduction in long-term P efflux.

Evaluating stocking of YOY pike Esox lucius as a tool in the restoration of shallow lakes

Summary1. Stocking of piscivores in shallow, eutrophicated lakes to reduce cyprinid densities is a common approach in lake restorations. Young‐of‐the‐year (YOY) pike Esox lucius are frequently used to reduce cyprinid densities, but their effectiveness is equivocal. This study uses a simple model to assess the efficacy of pike stocking as a lake restoration tool.2. The model evaluates YOY pike consumption in relation to different survival and growth patterns, timing of stocking, degree of piscivory of pike as well as YOY cyprinid growth patterns and productivity. The parameters used in the model are obtained from field surveys in eight study lakes stocked with YOY pike as well as from the literature.3. Our model showed that all parameters studied were important for predicting the effects of pike stocking on cyprinids. In particular, body size at stocking, cyprinid production and pike survival were good predictors of biomanipulation success.4. However, our model showed that only under very specific circumstances will stocking of YOY pike result in a reduction of YOY cyprinid densities large enough to affect water quality.5. The findings of this study question the efficacy of pike stocking as an appropriate and reliable tool for restoration programmes in shallow lakes, and indicate that when used efforts should be made to optimize the timing of stocking in relation to YOY cyprinid production and to increase the stocking body size of the pike.

Rapid response of macroinvertebrates to drainage management of shallow connected lakes

Summary Shallow lakes throughout the world are subject to drainage, either for fish harvesting or lake restoration. Lake drainage of fish lakes is known to improve macrophyte and zooplankton diversity, but the effect on the macroinvertebrate community is poorly known. In the present study, we investigated temporal trends in the macroinvertebrate community following drainage of six shallow connected lakes. Diversity increased for all macroinvertebrates (family level). Recolonization of the lakes occurred within the first year after the drainage and was supplemented with a set of species that were previously rare or did not occur in the lakes. Changes in the abiotic conditions of the lakes were small and transient, except for the decline in fish. The rapid recolonization by the species occurring before drainage is attributed to the high connectivity of our system. The appearance of supplementary species may relate to lowered fish predation, suggesting that fish were a dominant factor in shaping the communities. Synthesis and applications. Lake drainage has a positive effect on the diversity and richness of macroinvertebrates in shallow connected lakes. This positive effect may be due to a decline in fish predation following lake drainage in combination with a high rate of recolonization among others via connections to non‐drained lakes. Lake drainage, therefore, is probably the most cost‐effective lake restoration tool in shallow connected lakes. Other restoration tools may be preferable in isolated lakes where recolonization is constrained.

Testing aluminum addition as a tool for lake restoration in shallow, eutrophic Lake Sønderby, Denmark

Internal phosphorus (P) loading in shallow lakes may delay recovery from previous high external loading for decades. In Lake Sonderby (8 ha, mean depth 2.8 m), Fyn County, Denmark, this is especially true because there is no run-off of lake water during summer when high lake water P concentrations prevail. External P-loading was reduced in 1983 but still in 2001 total P reached 1.5 mg l−1 during summer. In the present study, we determined the size of the potential mobile P-pool in the sediment by use of a sequential extraction procedure. The potentially mobile P-pool (PMobile): Loosely adsorbed inorganic o-P (PWater), iron-bound o-P (PBD), and labile organic P (Org-PLabile) made up 14.6 g m−2 and constituted 40% of the Tot-P in the upper 10 cm sediment. Then, we tested if molar binding ratios of 4:1 or 8:1 between aluminum (Al) and potential mobile P could reduce sediment P-release at suboxic conditions. An Al:P ratio of 4:1 was enough (p<0.05; n=5) to trap all P in the sediment during a 39 days experiment with undisturbed sediment cores. This dosage was then tested in enclosures in the lake during a 30 days summer experiment with 3 replicate enclosures (1.1 m2, 2.1 m high) for each of the 2 treatments (Al addition, and control). o-P and Tot-P dropped from 1.28 mg l−1 to <0.006 and 0.02 mg l−1, respectively, in the Al treated enclosures but remained high in both control enclosures and in the lake water. Secchi depth increased from 0.8 m to the bottom upon Al treatment but declined to around 1.5 m after 4 days. By the end of the enclosure experiment, sediment analyses showed increased fractions of P\to NaOH in the surface sediment of Al treated enclosures. We conclude that Al addition was able to combat internal P-loading in the shallow lake when added in a molar ratio of 4:1 relative to the mobile P-pool in sediment and lake water. Meanwhile, temporary suppression of Daphnia grazing may be expected upon Al addition.

Top-down control of natural phyto- and bacterioplankton prey communities by Daphnia magna and by the natural zooplankton community of the hypertrophic Lake Blankaart

Biomanipulation, through the reduction of fish abundance resulting in an increase of large filter feeders and a stronger top-down control on algae, is commonly used as a lake restoration tool in eutrophic lakes. However, cyanobacteria, often found in eutrophic ponds, can influence the grazing capacity of filter feeding zooplankton. We performed grazing experiments in hypertrophic Lake Blankaart during two consecutive summers (1998, with and 1999, without cyanobacteria) to elucidate the influence of cyanobacteria on the grazing pressure of zooplankton communities. We compared the grazing pressure of the natural macrozooplankton community (mainly small to medium-sized cladocerans and copepods) with that of large Daphnia magna on the natural bacterioplankton and phytoplankton prey communities. Our results showed that in the absence of cyanobacteria, Daphnia magna grazing pressure on bacteria was higher compared to the grazing pressure of the natural zooplankton community. However, Daphnia grazing rates on phytoplankton were not significantly different compared to the grazing rates of the natural zooplankton community. When cyanobacteria were abundant, grazing pressure of Daphnia magnaseemed to be inhibited, and the grazing pressure on bacteria and phytoplankton was similar to that of the natural macrozooplankton community. Our results suggest that biomanipulation may not always result in a more effective top-down control of the algal biomass.

A simple model for evaluating the costs and benefits of aquatic macrophytes

Dense beds of aquatic macrophytes often cause nuisance to boaters and swimmers, and may obstruct water flow. Management of aquatic vegetation is, therefore, often aimed at reducing the biomass of the plants. If the nuisance is caused by exotic invasive species, there usually is no controversy with nature conservation aims. In shallow lakes, however, the interests of recreational users may conflict with nature conservation because the promotion of indigenous submerged vegetation is considered an important tool for lake restoration. Aiming at intermediate vegetation biomass seems a good solution for this controversy at first sight. However, we argue that such a compromise is often not the best policy from a welfare economic point of view. We present preliminary results of a graphical model, showing that the overall benefit for all ecosystem users may be minimal at the intermediate vegetation biomass. Furthermore, even if there is an optimal benefit at an intermediate macrophyte biomass, we argue that it is may not always be feasible to force the vegetation biomass to the desired level. Due to ecological feedback mechanisms, the system can have two alternative stable states: one with high vegetation biomass and one with little or no vegetation. It is concluded that it will often be better to realise a management strategy aimed at keeping some lakes (or parts of lakes) free of aquatic plants, whereas allowing others to be densely vegetated.

Top‐down or Bottom‐up Effects by Fish: Issues of Concern in Biomanipulation of Lakes

AbstractA large‐scale biomanipulation trial was carried out on Lake Vesijärvi in Finland during 1989–1993. Following the mass removal of coarse fish the biomass of cyanobacteria collapsed from 1.4 g/m−3 to below 0.4 g/m−3, while total phosphorus concentration declined from 45 μg/L to 30 μg/L. No relevant changes in zooplankton communities were observed. The results suggest that the success of food web manipulation as a tool for lake restoration is not necessarily dependent on the grazing rate of zooplankton. The effects of reduced fish‐mediated internal loading and recycling of nutrients are in many cases stronger than those of reduced planktivory. Alternative stable states of water quality may also exist in lakes not covered by macrophytes, owing to the changes in the behavior of fish stocks. Year‐to‐year variation in the littoral zone may cause large oscillations in lake ecosystems—for example, through the recruitment of fish. In addition, the nutrients translocated by fish from the littoral zone may affect the nutrient dynamics of the pelagial plankton community. In terms of phytoplankton species composition and the ratio of phosphorus to chlorophyll a, the water quality in Lake Vesijärvi has improved in a stepwise fashion within the last 10 years. This is probably due to the fact that the five‐year mass removal of fish in Enonselkä fulfilled the requirement of sustained management of fish stocks in order to maintain nonequilibrial conditions between alternate stable states. The prediction of the water quality development is obscured, however, by spatial and temporal within‐lake variation, which sets high requirements for sampling programs.

Can artificially generated gilvin (g440m-1, Gelbstoff) be used as a tool for lake restoration?

Can artificially generated gilvin (g440m^-1, Gelbstoff) be used as a tool for lake restoration?

Fish manipulation as a lake restoration tool in shallow, eutrophic, temperate lakes 2: threshold levels, long-term stability and conclusions

Fish manipulation as a lake restoration tool in shallow, eutrophic, temperate lakes 2: threshold levels, long-term stability and conclusions

Fish manipulation as a lake restoration tool in shallow, eutrophic temperate lakes 1: cross-analysis of three Danish case-studies

Fish manipulation as a lake restoration tool in shallow, eutrophic temperate lakes 1: cross-analysis of three Danish case-studies

Biomanipulation and its feasibility for water quality management in shallow eutrophic water bodies in The Netherlands

Biomanipulation as a tool for lake restoration is discussed mainly using literature data. It is based on the exploitation of the interactions both within and between the trophic levels in an aquatic ecosystem. Important among the interactions are: competition for light and nutrients between aquatic macrophytes and phytoplankton and among different phytoplankton species; grazing by planktonic and benthic filter feeders; and size-selective predation by fish. In several case studies biomanipulation has proved to be successful in restorating mildly eutrophic small waterbodies. However, for long-term stability of the restored ecosystems supplementary measures like reducing the external nutrient loadings are needed. The feasibility of the different biomanipulation measures to improve the water quality in shallow Dutch lakes is discussed. Preliminary results on biomanipulation experiments in enclosures withOscillatoria agardhii and the benthic filter feederDreissena polymorpha are given.