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1.
A large-scale enclosure experiment for lake restoration was carried out in Lake Wuli, a northern bay of shallow and eutrophic Lake Taihu in China. The large enclosure with an area of 10 ha was set up in the littoral zone and was bordered by waterproof fabric which did not cover the sediments. Multiple approaches were used and included fish removal, piscivorous fish stocking, shoreline reconstruction, aquatic macrophyte planting, benthic macro-animal stocking, and silver carp cultivation in pens for reduction of cyanobacteria. The results showed that the coverage of aquatic macrophytes increased from 0% to 45.7%. Mean concentrations of TN and TP inside the enclosure from May 2004 to May 2008 were 22.2% and 26.0% of those outside, respectively. Secchi depth was 0.40 m outside the enclosures and 0.75 m inside. However, responses of phytoplankton to the restoration project lagged behind improvement of water quality and reestablishment of aquatic plants. The phytoplankton biomass gradually decreased after the third year of the restoration. Stocking piscivorous fish and planting submerged macrophytes could not increase zooplankton biomass and enhance graze pressure on phytoplankton, most likely due to high omnivorous fish density and lower nutrition inside the enclosure. Higher grazing pressure of zooplankton on phytoplankton was observed in May and October every year. Zooplankton to phytoplankton biomass ratios were significantly negatively correlated with phytoplankton biomass outside (r = −0.440, p < 0.01) and inside the enclosure (r = −0.336, p < 0.05) from February 2004 to March 2007. Therefore, phytoplankton biomass inside and outside the enclosure was lower in May and October. Higher grazing pressure of zooplankton on phytoplankton in spring may result in occurrence of the clear-water phase that facilitated growth of submerged macrophytes in the littoral in Lake Wuli, and a clear-water state and improved water quality would likely be sustained throughout the year after reestablishment of submerged macrophytes. 相似文献
2.
Why biomanipulation can be effective in peaty lakes 总被引:1,自引:1,他引:0
The effects of fish stock reduction (biomanipulation) was studied in an 85 ha shallow peaty turbid lake. The lake cleared
in a 4-week period in April–May 2004, which demonstrated that biomanipulation can be effective in peaty lakes. We demonstrated
that it is possible to reduce the fish stock to <25 kg ha−1 benthivorous fish and <15 kg ha−1 planktivorous fish, sufficiently low to switch the lake from a turbid to a clear state. Knowledge of lake morphology, fish
stock, fish behaviour, and a variety of fishing methods was necessary to achieve this goal. It is expected that continuation
of fisheries to remove young of the year planktivorous species is needed for several years, until macrophytes provide sufficient
cover for zooplankton and can compete with phytoplankton. Cladocerans developed strongly after fish removal. The clearing
of the lake coincided with a sudden decrease of filamentous cyanobacteria and suspended detritus, and a strong increase of
Bosmina. We assume that Bosmina was able to reduce filamentous prokaryotes and detritus. After the disappearance of the cyanobacteria, Bosmina disappeared too. After the clearing of the lake Daphnia dominated in zooplankton and apparently was able to keep phytoplankton levels low. In our case, wind resuspension did not
prevent biomanipulation from being successful. No correlation between windspeed and turbidity was found, neither in an 85
ha nor in a 230 ha shallow peaty lake. Regression analysis showed that on average 50% of the amount of suspended detritus
can be explained by resuspension by fish and 50% by phytoplankton decomposition. The main goal of this biomanipulation experiment,
clear water and increased submerged plant cover in a shallow peaty lake, was reached. 相似文献
3.
Biomanipulation,new perspectives for restoration of shallow,eutrophic lakes in The Netherlands 总被引:9,自引:0,他引:9
S. H. Hosper 《Aquatic Ecology》1989,23(1):5-10
Eutrophication of Dutch lakes has led to massive algal growth, disappearance of most of the macrophytes and disturbance of the food chain. The pike population has fallen sharply and bream developed very strongly, in the absence of this predator. Eutrophication problems are primarily being tackled by reducing nutrient loading. Restoration of water quality, however, seems to be impeded by the present structure of the food chain,i.e. the large bream stock. Biomanipulation, especially fish stock control with the aim of reducing the bream stock and increasing that of predatory fish, can accelerate the process of restoration. For the further development of biomanipulation it is very important that water authorities and managers of fish stocks agree on a common strategy. 相似文献
4.
Freshwater ecology: changes, requirements, and future demands 总被引:5,自引:0,他引:5
R. G. Wetzel 《Limnology》2000,1(1):3-9
The past development and evolution of limnology as a discipline has demonstrated that experimentally controlled disturbances
of parts of aquatic ecosystems are essential for quantitative evaluation of causal mechanisms governing their operation. Correlative
analyses and modeling only establish hypotheses, not causality, and allow only therapeutic management applications. Rather
than constantly searching for differences, commonality must be sought. Among the large diversity of species, communities,
and biogeochemical processes controlling growth and reproduction, commonality emerges at the levels of regulation of metabolism.
Five areas of current and future limnological research are discussed in relation to greatest needs and promise to yield insights
into material and energy flows in freshwater ecosystems and their effective management: (1) coupled metabolic mutualism in
the physiological ecology of microbes (viruses, bacteria, fungi, and protists) and their biogeochemical, especially organic,
couplings with the environment; (2) biochemical regulation of collective metabolism, recycling, and bioavailability of nutrients
and growth regulators; (3) application of genetic and molecular techniques to addressing biogeochemical, evolutionary, and
pollution remediation problems; (4) recognition that the metabolism within lakes and streams is dependent upon and regulated
to a major extent by organic matter of the drainage basin and especially by the land-water interface biogeochemistry; and
(5) recognition that food-web alterations ("biomanipulation") are short-term, expensive therapeutic tools that may minimize
effects of eutrophication but will not solve or control eutrophication.
Received: October 30, 1999 / Accepted: December 6, 1999 相似文献
5.
Changes in the fish community structure and habitat use were followed after the introduction of pikeperch (Stizostedion lucioperca) to the roach-dominated Lake Gjersjøen. Quantitative echosounding showed that the density of juvenile roach (Rutilus rutilus) was dramatically reduced in pelagic areas, from 12 000–15 000 fish/ha to 250 fish/ha, while total fish density remained unchanged in littoral areas. At the same time, the habitat segregation between different size groups of roach was altered as larger roach utilized the pelagic zone after pikeperch introduction. The loss of the pelagic refuge for juvenile roach increased the availability of juvenile roach to littoral predators, notably perch. In littoral areas, the fish community changed from one dominated by roach (> 95%) to one dominated by perch (> 50%). 相似文献
6.
7.
For the removal of nutrients from eutrophic stream water polluted by non-point sources, an artificial aquatic food web (AAFW)
system comprising processes of phytoplankton growth and Daphnia magna grazing was developed. The AAFW system was a continuous-flow system constructed with one storage basin of 3 m3 capacity, one phytoplankton tank of 3 m3 capacity, and one zooplankton growth chamber of 1.5 m3 capacity. The system was optimized by setting hydraulic retention time of phytoplankton tank as 3 days and D. magna density as 740–1000 individual l−1. When the system was operated on eutrophic stream water that was delivering 471 g of total nitrogen (TN) and 29 g of total
phosphorus (TP) loadings for 45 days, 250 g (53%) of TN and 16 g (54%) of TP were removed from the water during its passage
through the phytoplankton tank. In addition, 64 g (14%) of TN and 4 g (13%) of TP were removed from the water by harvesting
zooplankton biomass in the zooplankton growth chamber, resulting in significant overall removal rates of TN (69%), nitrate
(78%), TP (73%), and dissolved inorganic phosphorus (94%). While the removal efficiency of the AAFW system is comparable to
those of other ecotechnologies such as constructed wetlands, its operation is less limited by the availability of space or
seasonal shift of temperature. Therefore, it was concluded that AAFW system is a highly efficient, flexible system for reducing
nutrient levels in tributary streams and hence nutrient loading to large aquatic systems receiving the stream water.
Handling editor: J. Padisak 相似文献
8.
The role of solid waste materials as habitats for macroinvertebrates in a lowland dam reservoir 总被引:2,自引:1,他引:1
Magdalena Czarnecka Małgorzata Poznańska Jarosław Kobak Norbert Wolnomiejski 《Hydrobiologia》2009,634(1):125-135
Eight hypereutrophic phytoplankton dominated ponds from the Brussels Capital Region (Belgium) were biomanipulated (emptied
with fish removal) to restore their ecological quality and reduce the risk of cyanobacterial bloom formation. Continuous monitoring
of the ponds before and after the biomanipulation allowed the effects of the management intervention on different compartments
of pond ecosystems (phytoplankton, zooplankton, submerged vegetation and nutrients) to be assessed. Fish removal resulted
in a drastic reduction in phytoplankton biomass and a shift to the clear-water state in seven out of eight biomanipulated
ponds. The reduction in phytoplankton biomass was associated with a marked increase in density and size of large cladocerans
in six ponds and a restoration of submerged macrophytes in five ponds. The phytoplankton biomass in the ponds with extensive
stands of submerged macrophytes was less affected by planktivorous fish recolonisation of some of the ponds later in the summer.
The two non-vegetated ponds as well as one pond with sparse submerged vegetation showed a marked increase in phytoplankton
biomass associated with the appearance of fish. Phytoplankton biomass increase coincided with the decrease in large Cladocera
density and size. One pond lacking submerged macrophytes could maintain very low phytoplankton biomass owing to large Cladocera
grazing alone. The results of this study confirmed the importance of large zooplankton grazing and revegetation with submerged
macrophytes for the maintenance of the clear-water state and restoration success in hypereutrophic ponds. They also showed
that large Cladocera size is more important than their number for efficient phytoplankton control and when cladocerans are
large enough, they can considerably restrain phytoplankton growth, including bloom-forming cyanobacteria, even when submerged
vegetation is not restored. The positive result of fish removal in seven out of eight biomanipulated ponds clearly indicated
that such management intervention can be used, at least, for the short-term restoration of ecological water quality and prevention
of noxious cyanobacterial bloom formation. The negative result of biomanipulation in one pond seems to be related to the pollution
by sewage water.
Guest editors: B. Oertli, R. Cereghino, A. Hull & R. Miracle
Pond Conservation: From Science to Practice. 3rd Conference of the European Pond Conservation Network, Valencia, Spain, 14–16
May 2008 相似文献
9.
First attempt to apply whole-lake food-web manipulation on a large scale in The Netherlands 总被引:12,自引:12,他引:0
Van Donk E. Grimm M. P. Gulati R. D. Heuts P. G. M. de Kloet W. A. van Liere L. 《Hydrobiologia》1990,200(1):291-301
Lake Breukeleveen (180 ha, mean depth 1.45 m), a compartment of the eutrophic Loosdrecht lakes system, was selected to study
the effects of whole-lake foodweb manipulation on a large scale. In Lake Loosdrecht (dominated by filamentous cyanobacteria),
due to water management measures taken from 1970–1984 (sewerage systems, dephosphorization) the external P load has been reduced
from 1.2 g m−2 y−1 to 0.35 g m−2 y−1. The water transparency (Secchi-depthca. 30 cm), however, has not improved. The aim of the food-web manipulation in Lake Breukeleveen was not only to improve the
light climate of the lake, but also to study if the successfull effects observed in small lakes (a few ha) can be upscaled.
In March 1989 the standing crop of planktivorous and bentivorous fish populations was reduced by intensive fishery, fromca. 150 kg ha−1 toca. 57 kg ha−1. The lake was made unaccessible to fish migrating from the other lakes and it was stocked with large-sized daphnids and 0+ pike. However, water transparency did not increase in the following summer and autumn 1989, which is in contrast with great
improvement in the light conditions previously observed in smaller lakes. The main explanations for the negative outcome in
Lake Breukeleveen are: 1) the rapid increase of the planktivorous fish biomass and carnivorous cladocerans, predating on the
zooplankton community; 2) suppression of the large daphnids by the high concentrations of filamentous cyanobacteria; 3) high
turbidity of the lake due to resuspension of bottom material induced by wind, unlike in smaller lakes, and thus inability
of submerged macrophytes to develop and to stabilize the ecosystem. 相似文献
10.
Accurate prediction of species changes in lake ecosystems following biomanipulation measures is of paramount importance in view of water quality management. The temporal variation of phytoplankton biomass as chlorophyll-a and transparency as Secchi depth measurements are studied in the Lake Bleiswijkse Zoom, The Netherlands, with a comprehensive structural dynamic model. In the formulation of the biological model, phytoplankton as several species, zooplankton, detritus, planktivores and benthivores, and piscivores are considered to be major contributing state variables for the model. The primary goal of this paper is to describe the possible impacts of several environmental scenarios on chlorophyll-a biomass qualitatively as it would help lake and environmental managers and relevant authorities elucidate the processes of eutrophication and biomanipulation in a broad way. Some of the scenarios that have been studied by this model are: (1) The effect of fixed stoichiometry in terms of internal nitrogen and phosphorus that are tied up within algal cells; (2) the effects of external phosphorus limitation; (3) light limitation and external nitrogen limitation on algal growth; (4) probable consequences that have taken place within the chlorophyll-a biomass due to change in biomasses of various aquatic organisms; and (5) possible changes of chlorophyll-a biomass due to higher temperatures caused by global warming. 相似文献