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Biomanipulation-induced reduction of sediment phosphorus release in a tropical shallow lake

Authors:
Xiufeng Zhang at Jinan University
Xiufeng Zhang
Yali Tang at Jinan University
Yali Tang
Erik Jeppesen at Aarhus University
Erik Jeppesen
Zhengwen Liu at Chinese Academy of Sciences
Zhengwen Liu
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Abstract and Figures

Biomanipulation via fish regulation combined with submerged plant introduction is an effective measure to restore eutrophic shallow lakes. Improved water quality and clarity promote growth of benthic algae, which with submerged plants may limit sediment phosphorus (P) release, thereby reinforce lake recovery. Our study sought to evaluate the effect of such a biomanipulation on water quality, benthic algal development and sediment P release in a shallow, tropical lake by (1) comparing porewater and lake water quality, light intensity and benthic algal development in restored and unrestored sections; (2) conducting a 32P radiotracer experiment to track P release from sediment cores sampled from both sections. The biomanipulation led to lower total P, total dissolved P, and soluble reactive P concentrations in lake water, lower phytoplankton biomass, and increased light intensity at sediment surface, stimulating benthic algal development. Moreover, sediment 32P release was lower in the restored than unrestored section. Concurrently, dissolved oxygen levels in upper layers of the sediment cores were higher in the restored section. Our study indicates that the biomanipulation improved water quality and enhanced growth of benthic algae, thereby reducing sediment P release, which may be one of the main mechanisms to create successful restoration.
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PRIMARY RESEARCH PAPER
Biomanipulation-induced reduction of sediment phosphorus
release in a tropical shallow lake
Xiufeng Zhang .Yali Tang .Erik Jeppesen .Zhengwen Liu
Received: 12 June 2016 / Revised: 18 November 2016 / Accepted: 10 December 2016 / Published online: 26 December 2016
ÓSpringer International Publishing Switzerland 2016
Abstract Biomanipulation via fish regulation com-
bined with submerged plant introduction is an effec-
tive measure to restore eutrophic shallow lakes.
Improved water quality and clarity promote growth
of benthic algae, which with submerged plants may
limit sediment phosphorus (P) release, thereby rein-
force lake recovery. Our study sought to evaluate the
effect of such a biomanipulation on water quality,
benthic algal development and sediment P release in a
shallow, tropical lake by (1) comparing porewater and
lake water quality, light intensity and benthic algal
development in restored and unrestored sections; (2)
conducting a
32
P radiotracer experiment to track P
release from sediment cores sampled from both
sections. The biomanipulation led to lower total P,
total dissolved P, and soluble reactive P concentrations
in lake water, lower phytoplankton biomass, and
increased light intensity at sediment surface, stimu-
lating benthic algal development. Moreover, sediment
32
P release was lower in the restored than unrestored
section. Concurrently, dissolved oxygen levels in
upper layers of the sediment cores were higher in the
restored section. Our study indicates that the bioma-
nipulation improved water quality and enhanced
growth of benthic algae, thereby reducing sediment
P release, which may be one of the main mechanisms
to create successful restoration.
Keywords Biomanipulation Submerged plant
Fish manipulation Restoration Induced benthic
algae Eutrophication Shallow lakes
Handling editor: Karl E. Havens
X. Zhang (&)Y. Tang Z. Liu
Department of Ecology and Institute of Hydrobiology,
Jinan University, Guangzhou 510632, China
e-mail: wetlandxfz@163.com
Y. Tang
e-mail: litangyali@163.com
Z. Liu
e-mail: zliu@niglas.ac.cn
X. Zhang
Cornell Biological Field Station, Department of Natural
Resources, Cornell University, Bridgeport, NY, USA
E. Jeppesen
Department of Bioscience & Arctic Research Centre
(ARC), Aarhus University, 8600 Silkeborg, Denmark
e-mail: ej@bios.au.dk
E. Jeppesen Z. Liu
Sino-Danish Centre for Education and Research (SDC),
The University of Chinese Academy, Beijing, China
Z. Liu
State Key Laboratory of Lake Science and Environment,
Institute of Geography and Limnology, Chinese Academy
of Sciences, Nanjing 210008, China
123
Hydrobiologia (2017) 794:49–57
DOI 10.1007/s10750-016-3079-x
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... As part of the restoration efforts, the Nanhu section has been subjected to biomanipulation through fish removal and macrophyte planting, and from 2010 and onwards about 85% of the sediment of Nanhu has been covered by submerged plants. Shortly after the biomanipulation, the restored section shifted to a clear-water state and has remained so for over eight years, with low plankton biomass (Zhang, et al., 2017, Liu et al, 2018. ...
... In addition, submerged plants are frequently reported to reduce phytoplankton growth (Gross et al., 2007) by producing allelopathic substances and competing nutrients, thereby maintaining a clear water state. In the Nanhu section, about 85% of the lake area was covered by submerged plants (Zhang et al., 2017) when the clear water samples were collected. P in aquatic systems continuously cycles between particulate and dissolved forms (Hudson et al., 1999). ...
Does differential phosphorus processing by plankton influence the ecological state of shallow lakes?
Article
  • Dec 2020
Shallow lakes have a tendency to settle into turbid or clear-water states, the latter having lower concentrations of total phosphorus (TP). However, how P-cycling is affected by and perhaps contributes to maintaining the different states is not well understood, in part because quantifying the processes involved by traditional methods is difficult. To elucidate these processes, we conducted experiments using 32P-PO4 as a tracer on samples collected from the unrestored, unvegetated sections of Huizhou West Lake where turbid water prevails as well as the restored, clear-water, macrophyte-rich waters of the lake. We measured PO4 uptake rates, 32P-PO4 accumulation by plankton per unit volume, including various fractions (picoplankton (0.2-2 μm), nanoplankton (2-20 μm) and microplankton (>20 μm)) as well as release rates of 32P-PO4 by labelled plankton. Our results revealed PO4 slow uptake in the turbid state due to low PO4 concentration, slow recycling, and high levels of particulate 32P which may allow for continuous high growth and biomass of phytoplankton. In contrast, in the clear water state, the uptake of PO4 was rapid due to a higher PO4 concentration, the recycling rates of 32P were high and the levels of particulate 32P low, potentially constraining the phytoplankton growth. A greater proportion of particulate 32P was in the microplankton fraction in clear waters, suggesting that grazing by microplankton may play an important role in the rapid P recycling in clear-waters. Our results provide some evidence for a reinforcement of the turbid conditions (low recycling rate) when the lake is in a turbid state and vice versa when in the clear water state. The results add new knowledge to the understanding of P cycling in shallow lakes and illustrates the utility of using P-kinetics in contrasting states in plankton communities. full text available: https://authors.elsevier.com/c/1cR39B8ccoRO8
View
... A significant contributory factor is increased growth of microbenthic algae owing to improved light conditions at the sediment surface (Hansson, 1990;Genkai-Kato et al., 2012). More benthic algae and less sedimentation of phytoplankton due to intensified grazing, and more benthic animals due to reduced fish predation, may all result in a higher redox potential in the surface sediment, potentially reducing the P release (Søndergaard et al., 2005;Zhang et al., 2013Zhang et al., , 2017. So far, the long-term perspectives of fish removal are less promising. ...
... Submerged macrophytes oxidize the sediment and increase its capacity of binding inorganic P, there by reducing P release to the water column (Carpenter and Lodge, 1986). In our study, the dominant species after plant introduction (Vallisnaria) has relatively well developed root systems (Xie et al., 2005;Zhang et al., 2010) and thus a high potential of oxidizing the sediment, thereby reducing the P release (Jessen et al., 2017;Zhang et al., 2017). Moreover, high water clarity and improved light conditions may allow development of benthic algae and consequently cause a reduction in the sediment P release (Hansson, 1990;Genkai-Kato et al., 2012;Zhang et al., 2013) in shallow lakes, such as Huizhou West Lake. ...
Successful restoration of a tropical shallow eutrophic lake: Strong bottom-up but weak top-down effects recorded
Article
  • Sep 2018
  • WATER RES
Fish manipulation has been used to restore lakes in the temperate zone. Often strong short-term cascading effects have been obtained, but the long term-perspectives are less clear. Fish manipulation methods are far less advanced for warm lakes, and it is debatable whether it is, in fact, possible to create a trophic cascade in warm lakes due to the dominance and high densities of fast-reproducing omnivorous fish. However, removal of benthic feeding fish also reduce disturbance of the sediment, which not only affects the nutrient level but also the concentration of suspended organic and inorganic matter with enhanced water clarity and potentially better growth conditions for submerged macrophytes. We conducted a biomanipulation experiment in one of the basins in Chinese Huizhou West Lake that have remained highly turbid after extensive nutrient loading reduction. Another basin was used as control (control-treatment pairing design). Removal of a substantial amount of plankti-benthivorous fish was followed by planting of submerged macrophytes and stocking of piscivorous fish. We found strong and relatively long-lasting effects of the restoration initiative in the form of substantial improvements in water clarity and major reductions in nutrient concentrations, particularly total phosphorus, phytoplankton and turbidity, while only minor effects were detected for crustacean zooplankton grazers occurring in low densities before as well as after the restoration. Our results add importantly to the existing knowledge of restoration of warm lakes and are strongly relevant, not least in Asia where natural lakes frequently are used extensively for fish production, often involving massive stocking of benthivorous fish. With a growing economy and development of more efficient fish production systems, the interest in restoring lakes is increasing world-wide.We found convincing evidence that fish removal and piscivores stocking combined with transplantation of submerged macrophytes may have significant effects on water clarity in warm shallow lakes even if the zooplankton grazing potential remains low, the latter most likely as a result of high predation on the zooplankton.
View
... Therefore, biomanipulation may be enhanced by the introduction of adequate species of submerged plants to restore eutrophic shallow lakes (Carignan and Kalff 1980;Jaynes and Carpenter 1986). Submerged plants improve cleanness of water and promote growth of useful benthic algae by directly taking up nutrients and pollutants, limiting phosphorus (P) release from sediment by oxidation of sediment and increasing the P-binding capacity of sediments and preventing sedimentation of particles in the water column that affects light assimilation by phytoplankton (Carignan and Kalff 1980;Blindow et al. 1993; Barko and James 1998;Zhang et al. 2017). This combined biomanipulation and submerged species treatment also promotes dominance of large-bodied Daphnia magna, showing high densities during spring and summer. ...
Eco-bioengineering tools in ecohydrological assessment of eutrophic water bodies
Article
Full-text available
  • May 2022
  • ECOTOXICOLOGY
Eutrophication of water bodies and deterioration of water quality are emerging environmental crises. The root causes and consequences of eutrophication are multidirectional. Thus, they provide a huge scope of risk-analysis and risk-assessment in the domain of remediation studies. However, recent restoration studies reveal a global trend of utilizing traditional restoration methods combined with advanced pioneer innovative techniques developed in the field of science and technology. This review introduces a novel approach to consider ecohydrological assessment of eutrophication by classical biomanipulation practices emphasising on their evolution into innovative ‘eco-bioengineering’ methods. The main objective of this study is to critically analyse and recognize the research gaps in classical biomanipulation and appreciate the reproducibility and efficacy of eco-bioengineering methods at micro- and macrolevel aquatic ecosystems. Comprehensive literature review was conducted on offline and online platforms. Our survey revealed (a) continuation of a historical trend in classical biomanipulation practices (61.64%) and (b) an ascending drift in eco-bioengineering research (38.36%) in the last decade (2010–2021). At a global scale, recent biomanipulation research has a skewed distribution in Europe (41.10%), East Asia (32.88%), North America (10.96%), South Africa (4.11%), South America (2.74%), Middle East (1.37%), Oceania (1.37%), and non-specific regions (5.48%). Finally, this review analysis revealed the comprehensiveness of eco-bioengineering methods and their strong ecological resilience to recurrence of eutrophication and fluctuating environmental flows in the future. Therefore, our review reinforces the supremacy of eco-bioengineering methods as cost-effective green technologies providing sustainable solutions to restore the eutrophic waters at a global scale.
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... Until recently, IPL control is not included in the priority list in most deep lake restoration programmes in tropical countries (See [44, [96][97][98] for literature on national restoration plans of several lakes in India, Thailand, and Indonesia). At the same time, most related research are case studies in shallow temperate lakes (e.g., [95,[99][100][101]) and in shallow subtropical and tropical lakes (e.g., [102,103]). ...
An application of Bayesian Belief Networks to assess management scenarios for aquaculture in a complex tropical lake system in Indonesia
Article
Full-text available
A Bayesian Belief Network, validated using past observational data, is applied to conceptualize the ecological response of Lake Maninjau, a tropical lake ecosystem in Indonesia, to tilapia cage farms operating on the lake and to quantify its impacts to assist decision making. The model captures ecosystem services trade-offs between cage farming and native fish loss. It is used to appraise options for lake management related to the minimization of the impacts of the cage farms. The constructed model overcomes difficulties with limited data availability to illustrate the complex physical and biogeochemical interactions contributing to triggering mass fish kills due to upwelling and the loss in the production of native fish related to the operation of cage farming. The model highlights existing information gaps in the research related to the management of the farms in the study area, which is applicable to other tropical lakes in general. Model results suggest that internal phosphorous loading (IPL) should be recognized as one of the primary targets of the deep eutrophic tropical lake restoration efforts. Theoretical and practical contributions of the model and model expansions are discussed. Short- and longer-term actions to contribute to a more sustainable management are recommended and include epilimnion aeration and sediment capping.
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... that affects light assimilation by phytoplankton(Carignan & Kalff 1980;Blindow et al. 1993;Barko & James 1998;Zhang X et al. 2017). This combined biomanipulation and submerged species treatment also promotes dominance of large-bodied Daphnia magna), showing high densities during spring and summer.Involvement of submerged macrophyted in biomanipulation experiments showed a positive effect on restoration of water quality and maintaining a healthy ecosystem, especially in temperate lakes in European countries. ...
Eco-bioengineering Tools in Ecohydrological Assessment of Eutrophic Water Bodies
Preprint
Full-text available
  • Jan 2021
Eutrophication of water bodies and deterioration of water quality is an emerging environmental crisis. The root causes, pathways and consequences of eutrophication are multidirectional and provide a huge scope of risk-analysis and risk-assessment in the domain of remediation studies. However, a deep insight on restoration studies shows a global transitional trend of evolution of traditional restoration methods to advanced innovative techniques with pioneering development in the field of science and technology. This study introduces a novel approach of considering ecohydrological assessment of eutrophication emphasizing classical biomanipulation practices and their evolution into innovative methods coined as ‘eco-bioengineering’ method. The main objective of this study is to critically analyse and recognize the research gaps in classical biomanipulations and appreciate the reproducibility and efficacy of eco-bioengineering methods at micro- and macrolevel aquatic ecosystems. Comprehensive literature review was conducted in offline and online planforms, and our survey revealed continuation of a historical trend in classical biomanipulation practices (75.36%) and an ascending drift in eco-bioengineering research (24.64%) in the immediate decade (2010–2020). At a global scale, recent biomanipulation research is skewedly distributed in Europe (43.48%), East Asia (34.78%), North America (8.70%), South America (2.90%), South Africa (4.35%), Oceania (1.45%), Middle East (1.45%) and non-specific regions (2.90%). Finally, this study revealed the comprehensiveness of eco-bioengineering methods and their strong ecological resilience to recurrence of eutrophication and fluctuating environmental flows in the future. Therefore, this study reinforces eco-bioengineering methods a cost-effective green technologies that will sustainable solutions for restoration of eutrophic waters at a global scale.
View
Do submerged macrophytes facilitate the development of large crustacean zooplankton in tropical shallow lakes?
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Full-text available
  • Jul 2023
  • HYDROBIOLOGIA
In temperate shallow lakes, submerged macrophytes facilitate zooplankton development by providing refuge against fish predation and, thereby, indirectly contribute to maintaining a clear-water state through enhanced zooplankton grazing. The role of macrophytes for zooplankton and their grazing potential is less clear for tropical lakes. We investigated crustacean zooplankton in a phytoplankton-dominated basin (algal basin) and two restored basins dominated by macro-phytes (macrophyte basins) in the shallow Huizhou West Lake in tropical southern China. We found that copepods prevailed in all basins, but the dominant taxon differed , with omnivorous cyclopoids dominating in the algal basin and herbivorous calanoids in the macrophyte basins. Moreover, the biomass ratios of calanoid:copepod and zooplankton:phytoplankton were higher in the macrophyte basins than in the algal basin. Our results suggest that restoration measures involving macrophyte transplantation and fish removal lead to reduced fish predation on zooplankton, which help to maintain the clear-water state when macrophytes are established due to higher control on phytoplankton. However, unlike in temperate lakes, large-bodied Daphnia were generally absent and the zooplankton:phytoplankton ratio was overall low, indicating a weaker top-down control in tropical lakes, which is likely due to higher fish predation.
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View
Carbon transfer from the submerged macrophyte Hydrilla verticillata to zooplankton: a 13C-labeled mesocosm study
Article
Full-text available
  • Jun 2021
  • HYDROBIOLOGIA
Submerged macrophytes cannot be utilized directly by zooplankton. However, vegetation can serve as an organic carbon resource for heterotrophic bacteria, which are themselves accessible to zooplankton. We therefore hypothesize that submerged macrophytes supply a carbon source to zooplankton by increasing the availability of food such as heterotrophic bacteria. Here, we used stable carbon isotope (13C) labeling to trace the carbon flow from submerged macrophytes to zooplankton with a mesocosm experiment. The carbon stable isotope ratios of zooplankton and their potential food sources were analyzed in mesocosms planted with 13C-labeled Hydrilla verticillata (L. f.) Royle in comparison with the control in which plastic plants were planted. We found that all potential food resources of zooplankton, including phytoplankton, bacterioplankton, macrophyte-associated epiphyton and epibacteria, were significantly enriched with 13C in the presence of 13C-enriched H. verticillata. Zooplankton were significantly more enriched with 13C than phytoplankton, epiphyton and bacterioplankton but significantly less enriched with 13C than epibacteria. Based on a stable isotopic mixing model, we found a macrophyte carbon contribution of 30.5% to epibacteria and 14.7% to zooplankton. Our results indicated that macrophytes might be used by zooplankton as a carbon resource, mainly via a pathway involving epibacteria attached to macrophytes.
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Interactions of fish, algae, and abiotic factors in a shallow, tropical pond
Article
Full-text available
  • Nov 2020
  • HYDROBIOLOGIA
Protecting and restoring shallow tropical lakes and wetlands requires a knowledge of what shapes and controls algal dynamics and primary productivity in these systems. Algal community structure and composition can be regulated either through biotic or abiotic controls. Large-scale changes in fish populations can affect algal communities by altering food web dynamics and the physical and chemical properties of the aquatic environment. A reduction in fish biomass can lead to a reduction in algal biomass because of increased grazing by zooplankton and reduced availablity of nutrients. However, the omnivorous fish common in tropical systems often consume algae, and their reduction can increase algal biomass. There is a need for more information on the effect of fish removals/reductions in tropical systems. In a five-year study of a shallow, tropical pond in Hawaii, I investigated the water quality effects of tilapia removal following the occurrence of two natural fish die-offs. I describe the concurrent impacts of water-level fluctuations and the fish die-offs on the physical and chemical conditions of the pond and the subsequent changes in the algal community. Overall, nutrients, suspended sediment, organic matter, and algal biomass were significantly reduced and light availability significantly increased in the absence of tilapia.
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Restoration of Shallow Lakes in Subtropical and Tropical China: Response of Nutrients and Water Clarity to Biomanipulation by Fish Removal and Submerged Plant Transplantation
Article
Full-text available
  • Oct 2016
Fish removal has been used to restore temperate lakes, and positive effects on ecological state and water clarity have frequently been recorded in many lakes. Recently, a supplementary measure, transplantation of submerged macrophytes after fish removal, has been applied to restore warm Chinese shallow lakes in order to compensate for the expected lack of increasing grazing control of phytoplankton after the biomanipulation. These measures have successfully shifted turbid warm lakes to a clear water state, but little is known about the responses to restoration of key physico-chemical variables. We analyzed the seasonal variation in nutrient concentrations in two subtropical and one tropical biomanipulated shallow Chinese lakes subjected to restoration. In all three lakes, a marked decline occurred in the concentrations of lake total nitrogen (TN), total phosphorus (TP), total suspended solids (TSS), and chlorophyll a (Chl a), while the transparency (SD:WD ratio, Secchi depth to water depth ratio) increased. A clear water state was established, lasting so far for 7 to 23 months, and TN, TP, Chl a, and TSS levels in the three restored lakes decreased to, on average, 49%, 58%, 41%, and 18% of the level prior to restoration and/or the level in a reference lake, respectively, while the annual mean SD:WD ratio exhibited a 1.5–4 fold increase. In conclusion, lake restoration by transplantation of submerged macrophytes after fish removal had major positive effects on the physico-chemical variables in our study lakes. However, continuous control of omnivorous and herbivorous fish biomass is recommended as the fish typically present in warm, shallow lakes to some extent feed on submerged macrophytes, when available.
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Biomanipulation of fish assemblages as a lake restoration technique
Article
Full-text available
  • Sep 1999
  • Arch Hydrobiol
We searched the limnological literature to assess the success of biomanipulation projects with respect to improvement of water quality in culturally eutrophic lakes and reservoirs. We reviewed 41 biomanipulation experiments (from 63 published papers/books) involving the reduction of zooplanktivorous and benthivorous fish abundances in 39 lakes. We divided the experiments into five categories based on the type of biomanipulation performed: piscivore stocking, piscivore stocking + partial fish removal, partial fish removal, elimination of fish, and elimination of fish followed by restocking. We judged success (consistently successful, partially successful, unsuccessful) by changes in water quality variables; primarily phytoplankton or chlorophyll biomass and water transparency, during the post-implementation period of each study. The percentage of consistently successful manipulations varied with approach: piscivore stocking (28.6 %), piscivore stocking + partial fish removal (60.0 %), partial fish removal (90.0 %), elimination of fish (40.0 %), and elimination of fish followed by restocking (66.7 %). Overall, 61 % of the biomanipulations were consistently successful in improving water quality, with most successful attempts involving small, shallow lakes (< 25 ha, mean depth < 3 m). Only 14.6 % of the biomanipulations were unsuccessful in improving water quality for at least one year. Biomanipulations resulting in increased abundances of Daphnia and macrophytes were most likely to achieve stable clear water states and maintain improved water quality.
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Shallow lake restoration by nutrient loading reduction—some recent findings and challenges ahead
Article
  • Jun 2007
Shallow lakes respond to nutrient loading reductions. Major findings in a recent multi-lake comparison of data from lakes with long time series revealed: that a new state of equilibrium was typically reached for phosphorus (P) after 10–15 years and for nitrogen (N) after <5–10 years; that the in-lake Total N:Total P and inorganic N:P ratios increased; that the phytoplankton and fish biomass often decreased; that the percentage of piscivores often increased as did the zooplankton:phytoplankton biomass ratio, the contribution of Daphnia to zooplankto biomass, and cladoceran size. This indicates that enhanced resource and predator control often interact during recovery from eutrophication. So far, focus has been directed at reducing external loading of P. However, one experimental study and cross-system analyses of data from many lakes in north temperate lakes indicate that nitrogen may play a more significant role for abundance and species richness of submerged plants than usually anticipated when total phosphorus is moderate high. According to the alternative states hypothesis we should expect ecological resistance to nutrient loading reduction and P hysteresis. We present results suggesting that the two alternative states are less stable than originally anticipated. How global warming affects the water clarity of shallow lakes is debatable. We suggest that water clarity often will decrease due to either enhanced growth of phytoplankton or, if submerged macrophytes are stimulated, by reduced capacity of these plants to maintain clear-water conditions. The latter is supported by a cross-system comparison of lakes in Florida and Denmark. The proportion of small fish might increase and we might see higher aggregation of fish within the vegetation (leading to loss of zooplankton refuges), more annual fish cohorts, more omnivorous feeding by fish and less specialist piscivory. Moreover, lakes may have prolonged growth seasons with a higher risk of long-lasting algal blooms and at places dense floating plant communities. The effects of global warming need to be taken into consideration by lake managers when setting future targets for critical loading, as these may well have to be adjusted in the future. Finally, we highlight some of the future challenges we see in lake restoration research.
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The effect of biomanipulation on phosphorus exchange between sediment and water in shallow, tropical Huizhou West Lake, China
Article
  • Jan 2017
  • LIMNOLOGICA
Three shallow basins in Huizhou West Lake, China, were compared with respect to phosphorus (P) cycling between sediment and water, binding forms of P in sediment, and macrophyte biomass. The basins had similar sediments and similar depths, but two of the basins were restored by carp fish removal and macrophyte transplantation. These two basins have had clear water, low Chl.a and high macrophyte coverage for seven and ten years, whilst the unrestored control basin had turbid water and higher Chl.a. Judged by diffusive ammonium efflux, sediments in restored basins had higher mineralization rates than the unrestored basin, but the release of total dissolved P were more similar. However, sediments of restored basins released primarily dissolved organic P, while the sediment from the unrestored basin only released dissolved inorganic P. One third of the P release in the unrestored basin occurred from resuspended sediment, while this pathway contributed less than 3% in restored basins where resuspension rates were 10 times lower and the surface sediments affinity for phosphate higher. Besides from the presence of carps in the unrestored basin, the main differences were a large pool of P (700–850 mg P m⁻²) in macrophyte biomass and a smaller pool (∼150 mg m⁻²) as loosely adsorbed P in the sediment of restored basins than in the unrestored (0 in macrophytes and 350 mg P m⁻² as loosely adsorbed). Also, a tendency of higher concentrations of oxidized iron was observed in the surface sediment from restored basins. The study underlines the potential of trophic structure changes to alter internal nutrient cycling in shallow lakes.
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Interstitial Ion Concentrations as an Indicator of Phosphorus Release and Mineral Formation in Lake Sediments
Chapter
  • Jan 1986
Interstitial ion profiles of P, Fe, Mn, Ca, and sulfide were examined for cores from two Wisconsin lakes with different limnological characteristics. Interstitial ion concentrations were affected by environmental conditions and sediment type, and could be used to explain previously observed differences in sediment phosphorus release between the two lakes. Calculated ion activity products were used to assess the effects of various mineral phases on the control of interstitial ion concentrations. Under anoxic conditions, vivianite formation may control phosphorus concentrations in the noncalcareous Lake Minocqua sediments, while Lake Mendota interstitial waters approached saturation with respect to both vivianite and whitlockite and were oversaturated with respect to anapaite and hydroxyapatite. The effects of pH on the formation of various mineral phases appeared to be a major factor controlling interstitial ion concentrations.
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Successful restoration of a tropical shallow eutrophic lake: strong bottom-up but weak top-down effects recorded
Conference Paper
  • Oct 2014
Fish manipulation has been used to restore lakes in the temperate zone. Often strong shortterm cascading effects have been obtained, but the long term-perspectives are less clear. Fish manipulation methods are far less advanced for warm lakes, and it is debatable whether it is, in fact, possible to create a trophic cascade in warm lakes due to the dominance and high densities of fast-reproducing omnivorous fish. However, other important aims of fish manipulation, for instance, the removal of benthic feeding fish, are to reduce disturbance of the sediment, which not only affects the nutrient level but also the concentration of suspended organic and inorganic matter with reduced clarity as a result, and hampers growth of submerged macrophytes. We conducted a biomanipulation experiment in two basins of Chinese Huizhou West Lake that has remained highly turbid after extensive nutrient loading reduction. A third basin was used as control (controltreatment pairing design). Removal of a substantial amount of plankti-benthivorous fish was followed by planting of submerged macrophytes and stocking of piscivorous fish. We found strong and relatively long-lasting effects of the restoration initiative in the form of substantial improvements in water clarity and major reductions in nutrient concentrations, particularly total phosphorus, phytoplankton and turbidity, while only minor effects were detected for crustacean zooplankton grazers occurring in low densities before, as well as after the restoration. Our results add importantly to the existing knowledge of restoration of warm lakes and are strongly relevant, not least in Asia where natural lakes frequently are used extensively for fish production, often involving massive stocking of benthivorous fish. With a growing economy and development of more efficient fish production systems, the interest in restoring lakes is increasing world-wide. We found convincing evidence that fish removal and piscivores stocking combined with transplantation of submerged macrophytes may have a substantial role in conservation and management of warm water lakes.
View
Effects of Submerged Aquatic Macrophytes on Nutrient Dynamics, Sedimentation, and Resuspension
Chapter
  • Jan 1998
Accelerated eutrophication due to excessive nutrient (particularly P) loadings has led to great interest in the role of submerged macrophytes in the nutritional economy of freshwater aquatic systems. Submerged macrophytes are unique among rooted aquatic vegetation because they link the sediment with overlying water. This linkage is responsible for great complexities in nutrition and has important implications for nutrient cycling. Despite increased attention to vegetated shallow water systems within the past 20 years, no consensus exists on whether submerged macrophytes function as sources or sinks for particular nutrients. As a result, it has been necessary to evaluate quantitatively nutrient source-sink relationships, involving both soluble and particulate nutrient fractions.
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Influence of benthic diatoms on the nutrient release from sediments of shallow lakes recovering from eutrophication
Article
  • Dec 1995
Measures taken to combat eutrophication resulted in a decrease in phytoplankton chlorophyll and an increase in transparency in the lakes studied. Because of the low nutrient concentrations in the overlying water, the increased light availability and the relatively nutrient rich sediments, a benthic algae community developed. In this study the interactions between the benthic algae and the nutrient release from the sediments is examined. In laboratory experiments it is demonstrated that benthic diatoms are able to grow on nutrients released from the sediments. The direct result is a decrease of the nutrient flux from the sediments by uptake by benthic diatoms. An indirect effect is an increased loss of nitrogen from the sediment water system to the atmosphere by stimulation of the coupled nitrification-denitrification. This is caused by an increased O-2 penetration depth due to the photosynthesis of benthic diatoms. Based upon these laboratory results and additional calculations, it is concluded that the benthic diatoms in the field are able to reduce the nutrient release from the sediments and thus the availability for the phytoplankton. The benthic diatoms therefore may accelerate the process of recovery from eutrophication.
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