scholarly journals Application of the Conditional Nonlinear Optimal Perturbations Method in the Shallow Lake Ecological Degradation and Restoration

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Bo Wang ◽  
Qianqian Qi
Keyword(s):  
Shallow Lake ◽  
Sediment Resuspension ◽  
Finite Amplitude ◽  
Water Transparency ◽  
Lake Ecosystem ◽  
Lake Ecosystems ◽  
Ecological Degradation ◽  
Parameter Condition ◽  
Restoration Model ◽  
Simple Combination

In the shallow lake ecosystems, the recovery of the aquatic macrophytes and the increase in the water transparency have been the main contents of the ecological restoration. Using the shallow lake ecological degradation and restoration model, CNOP method is adopted to discuss the instability and sensitivity of the ecosystem to the finite-amplitude perturbations related to the initial condition and the parameter condition. Results show that the linearly stable clear (turbid) water states can be nonlinearly unstable with the finite-amplitude perturbations, which represent the nature factors and the human activities such as the excessive harvest of the macrophytes and the sediment resuspension caused by artificially dynamic actions on the ecosystems. The results also support the viewpoint of Scheffer et al., whose emphasis is that the facilitation interactions between the submerged macrophytes and the water transparency are the main trigger for an occasional shift from a turbid to a clear state. Also, by the comparison with CNOP-I, CNOP-P, CNOP, and (CNOP-I, CNOP-P), results demonstrate that CNOP, which is not a simple combination of CNOP-I and CNOP-P, could induce the shallow lake ecosystem larger departure from the same ground state rather than CNOP-I, CNOP-P, and (CNOP-I, CNOP-P).

Application of the CNOP Method in the Shallow Lake Ecosystem

2014 ◽  
Vol 1010-1012 ◽  
pp. 658-661 ◽  
Author(s):  
Qian Qian Qi ◽  
Bo Wang
Keyword(s):  
Ecological Restoration ◽  
Shallow Lake ◽  
Submerged Macrophytes ◽  
Finite Amplitude ◽  
Water Transparency ◽  
Lake Ecosystem ◽  
Initial Condition ◽  
Turbid Water ◽  
Variable Model

It is serious on the degradation of the shallow lake ecosystem at present, while the recovery of the macrophytes vegetations and the increase in water transparency have been the main contents of the ecological restoration. Using a two-variable model, we discuss the instability and sensitivity of the ecosystem to the finite-amplitude perturbations related to the initial condition with CNOP-I method. Results show that the linearly stable clear (turbid) water states can be nonlinearly unstable with the finite-amplitude perturbations. The results also demonstrate that the facilitation interactions between the submerged macrophytes and the water transparency are the main trigger for a shift from the turbid to the clear state.

Field Observation and Simulation of Sediment Resuspension in a Shallow Lake

1988 ◽  
Vol 20 (6-7) ◽  
pp. 263-270 ◽  
Author(s):  
K. Otsubo ◽  
K. Muraoka
Keyword(s):  
Numerical Simulation ◽  
Shallow Lake ◽  
Water Wave ◽  
Field Data ◽  
Sediment Resuspension ◽  
Field Research ◽  
Lake Kasumigaura ◽  
Bed Erosion ◽  
Current Water ◽  
Good Agreement

The dispersion and resuspension of sediments in Takahamairi Bay basin of Lake Kasumigaura were studied by means of field research and numerical simulation. The field data on wind direction and velocity, lake current, water wave, and turbidity were shown. Based on these results, we discuss how precipitated sediments were resuspended in this shallow lake. To predict the turbidity and the depth of bed erosion, a simulation model was established for this lake. The calculated turbidity showed good agreement with the field data. According to the simulated results, the turbidity reaches 200 ppm, and the bed is eroded several millimeters deep when the wind velocity exceeds 12 m/s in the lake.

scholarly journals Antecedent lake conditions shape resistance and resilience of a shallow lake ecosystem following extreme wind storms

2021 ◽  
Author(s):  
Michael W. Thayne ◽  
Benjamin M. Kraemer ◽  
Jorrit P. Mesman ◽  
Bastiaan W. Ibelings ◽  
Rita Adrian
Keyword(s):  
Shallow Lake ◽  
Lake Ecosystem ◽  
Extreme Wind ◽  
Wind Storms

3. Sunlight and motion

2018 ◽  
pp. 26-47
Author(s):  
Warwick F. Vincent
Keyword(s):  
Ecosystem Services ◽  
The State ◽  
Slow Waves ◽  
Habitat Characteristics ◽  
Water Transparency ◽  
Lake Ecosystem ◽  
Physical Habitat ◽  
State Of Health ◽  
Temperature Water

Water transparency powerfully indicates the state of health of a lake ecosystem. The water’s turbidity defines the physical habitat characteristics of lakes, strongly influencing their chemistry, biology, and ecosystem services. ‘Sunlight and motion’ explains the methods for measuring water transparency and how the penetration of sunlight into water declines with depth. The different colours, hues, and brightness levels of lakes are due to the materials dissolved and suspended within them. The layering of different temperature water in lakes is also described. This stratification varies greatly with the seasons. Mixing of the waters is mainly due to slow waves at and just below the surface as well as deeper currents.

scholarly journals High net CO<sub>2</sub> and CH<sub>4</sub> release at a eutrophic shallow lake on a formerly drained fen

2016 ◽  
Vol 13 (10) ◽  
pp. 3051-3070 ◽  
Author(s):  
Daniela Franz ◽  
Franziska Koebsch ◽  
Eric Larmanou ◽  
Jürgen Augustin ◽  
Torsten Sachs
Keyword(s):  
Global Warming ◽  
Shallow Lake ◽  
Typha Latifolia ◽  
Open Water ◽  
Emergent Vegetation ◽  
Lake Ecosystem ◽  
Co2 Uptake ◽  
Mild Winter ◽  
Ch4 Emissions ◽  
Northeastern Germany

Abstract. Drained peatlands often act as carbon dioxide (CO2) hotspots. Raising the groundwater table is expected to reduce their CO2 contribution to the atmosphere and revitalise their function as carbon (C) sink in the long term. Without strict water management rewetting often results in partial flooding and the formation of spatially heterogeneous, nutrient-rich shallow lakes. Uncertainties remain as to when the intended effect of rewetting is achieved, as this specific ecosystem type has hardly been investigated in terms of greenhouse gas (GHG) exchange. In most cases of rewetting, methane (CH4) emissions increase under anoxic conditions due to a higher water table and in terms of global warming potential (GWP) outperform the shift towards CO2 uptake, at least in the short term.Based on eddy covariance measurements we studied the ecosystem–atmosphere exchange of CH4 and CO2 at a shallow lake situated on a former fen grassland in northeastern Germany. The lake evolved shortly after flooding, 9 years previous to our investigation period. The ecosystem consists of two main surface types: open water (inhabited by submerged and floating vegetation) and emergent vegetation (particularly including the eulittoral zone of the lake, dominated by Typha latifolia). To determine the individual contribution of the two main surface types to the net CO2 and CH4 exchange of the whole lake ecosystem, we combined footprint analysis with CH4 modelling and net ecosystem exchange partitioning.The CH4 and CO2 dynamics were strikingly different between open water and emergent vegetation. Net CH4 emissions from the open water area were around 4-fold higher than from emergent vegetation stands, accounting for 53 and 13 g CH4 m−2 a−1 respectively. In addition, both surface types were net CO2 sources with 158 and 750 g CO2 m−2 a−1 respectively. Unusual meteorological conditions in terms of a warm and dry summer and a mild winter might have facilitated high respiration rates. In sum, even after 9 years of rewetting the lake ecosystem exhibited a considerable C loss and global warming impact, the latter mainly driven by high CH4 emissions. We assume the eutrophic conditions in combination with permanent high inundation as major reasons for the unfavourable GHG balance.

Regime shifts in shallow lake ecosystems along an urban-rural gradient in central China

2020 ◽  
Vol 733 ◽  
pp. 139309
Author(s):  
Yanmin Cao ◽  
Peter Langdon ◽  
Xu Chen ◽  
Chunling Huang ◽  
Yi Yan ◽  
...  
Keyword(s):  
Shallow Lake ◽  
Regime Shifts ◽  
Central China ◽  
Lake Ecosystems ◽  
Urban Rural

Landlocked Atlantic salmon in a large river-lake ecosystem: managing an endemic, large-bodied population of high conservation value

2020 ◽  
Author(s):  
Larry A. Greenberg ◽  
Johnny R. Norrgård ◽  
Pär Gustafsson ◽  
Eva Bergman
Keyword(s):  
Carrying Capacity ◽  
Habitat Restoration ◽  
Life Stage ◽  
Large River ◽  
Lake Ecosystem ◽  
Lake Ecosystems ◽  
Large Size ◽  
Salmon Population ◽  
High Conservation ◽  
Sustainable Fishery

Managing and conserving threatened migratory salmonid populations in large river-lake ecosystems is challenging not only because of the ecosystems’ large size, but also because there is often more than one anthropomorphic stressor. The River Klarälven-Lake Vänern ecosystem, situated in Norway and Sweden, is a large highly modified ecosystem, home to a threatened, endemic, large-bodied population of landlocked salmon. With 11 dams, the salmon population has been maintained through extensive stocking and a truck and transport system for spawners. Here we review what we have learned about the salmon after 15 years of research, highlighting the major findings for each life stage. Our studies indicate that the salmon population is below carrying capacity, and we suggest measures to increase the number of spawners and downstream passage success. Habitat restoration to compensate for losses from former log driving activities is expected to further increase carrying capacity. Re-establishing salmon in Klarälven’s upper reaches in Norway, while possible, is fraught with both ecological and legislative hurdles. Substantial long-term funding is needed to foster co-management and ensure a sustainable fishery.

scholarly journals Macroinvertebrates and Microbes (Archaea, Bacteria) Offer Complementary Insights into Mine-Pit Lake Ecology

2019 ◽  
Vol 39 (3) ◽  
pp. 589-602 ◽  
Author(s):  
Melanie L. Blanchette ◽  
Richard Allcock ◽  
Jahir Gonzalez ◽  
Nina Kresoje ◽  
Mark Lund
Keyword(s):  
Water Chemistry ◽  
Environmental Drivers ◽  
Sediment Chemistry ◽  
Lake Ecosystem ◽  
Pit Lake ◽  
Lake Ecosystems ◽  
Assemblage Composition ◽  
Management Actions ◽  
Pit Lakes ◽  
Broad Objective

Abstract The broad objective of this research was to determine the environmental drivers of macroinvertebrate and microbial assemblages in acidic pit lakes. This is important because pit lake ecosystem development is influenced by prevailing environmental characteristics. Three lakes (Stockton, Kepwari, WO5H) within a larger pit-lake district in Collie, Western Australia were surveyed for spatial variability of benthic macroinvertebrate and microbe (Archaea, Bacteria) assemblage composition as well as potential environmental drivers (riparian condition, aquatic habitat, sediments, and aquatic chemistry) of assemblages. With the exception of sediment chemistry, biophysical variables were significantly different across lakes and reflected riparian condition and groundwater chemistry. Microbial assemblages in pit lakes were significantly different across lakes and correlated with water chemistry, particularly metals in Lake WO5H. However, the most abundant microbes were not readily identified beyond class, making it difficult to speculate on their ecological function. Macroinvertebrate assemblage composition and species richness were also significantly different across all lakes, and in Lake WO5H (a lake with low pH and high metal concentrations), taxa were correlated with benthic organic matter as well as water chemistry. Results indicated that despite poor water quality, input of nutrients from terrestrial leaf litter can support or augment pit lake ecosystems. This is a demonstration of the concept that connection of pit lakes to catchments can positively affect aquatic ecosystems, which can inform management actions for remediation.

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