scholarly journals A Three-Dimensional Coupled Hydrodynamic-Ecological Modeling to Assess the Planktonic Biomass in a Subalpine Lake

2021 ◽  
Vol 13 (22) ◽  
pp. 12377
Author(s):  
Wen-Cheng Liu ◽  
Hong-Ming Liu ◽  
Rita Sau-Wai Yam
Keyword(s):  
Water Quality ◽  
Sensitivity Analysis ◽  
Ecological Model ◽  
Three Dimensional ◽  
Ecological Status ◽  
Coupled Model ◽  
Zooplankton Biomass ◽  
Subalpine Lake ◽  
Depth Water ◽  
Temperature Water

In this study, a coupled three-dimensional hydrodynamic-ecological model was developed to comprehensively understand the interaction between the hydrodynamics and ecological status of a lake. The coupled model was utilized to explore the hydrodynamics, water quality, and ecological status in an ecologically rich subalpine lake (i.e., Tsuei-Feng Lake (TFL), located in north-central Taiwan). The measured data of water depth, water temperature, water quality, and planktonic biomass were gathered to validate the coupled model. The simulated results with a three-dimensional hydrodynamic and water quality-ecological model reasonably reproduced the variations in observed water depth, water temperature, water quality, and phytoplankton and zooplankton biomass. Sensitivity analysis was implemented to determine the most influential parameter affecting the planktonic biomass. The results of sensitivity analysis indicated that the predation rate on phytoplankton (PRP) significantly affects the phytoplankton biomass, while the basal metabolism rate of zooplankton (BMZ) importantly affects the zooplankton biomass. Furthermore, inflow discharge was the most important environmental factor dominating the phytoplankton and zooplankton biomass of TFL. This implies that the runoff in the catchment area caused by rainfall and the heavy rainfall induced by climate change may affect the planktonic biomass of the lake.

scholarly journals Current state and long-term changes in the mesozooplankton community of the Ukrainian and Georgian parts of the Black Sea as indicators of its ecological status

2021 ◽  
Vol 29 (1) ◽  
pp. 47-58
Author(s):  
Y. V. Kharytonova ◽  
M. V. Nabokin ◽  
M. M. Mgeladze ◽  
P. A. Vadachkoria ◽  
V. G. Dyadichko
Keyword(s):  
Water Quality ◽  
Black Sea ◽  
Coastal Waters ◽  
Ecological Status ◽  
High Water ◽  
Zooplankton Biomass ◽  
The Black Sea ◽  
Mesozooplankton Community ◽  
Noctiluca Scintillans ◽  
Average Abundance

Water quality assessment is a key task of any measures in the field of water use, environmental management and protection. Thus, it is necessary to conduct systematic monitoring to assess the ecological state in the marine waters and to develop a strategy for its recovery. Anthropogenic impacts of various types leading to eutrophication and pollution of the Black Sea are changing the main characteristics of all components of the aquatic ecosystem. Zooplankton plays a key role in the pelagic food web. This article presents the results of the research on the state of zooplankton which was conducted during the Ukrainian-Georgian expedition in the framework of the international project “Emblas-plus” during 2016, 2017 and 2019. The ecological quality class of the investigated Black Sea waters was determined by the zooplankton integrated index (IZI). In Ukrainian waters in total, 49 taxa of zooplankton were registered. In 2017 taxonomic composition of zooplankton was more diverse (36 taxa in 2016, 35 in 2019). In Georgian waters in 2019, 40 taxa of mesozooplankton were registered, most of them are widespread forms in the Black Sea. The most diverse group is Crustacea (Cladocera and Copepoda).The most prevalent crustaceans were the eurythermic species, an important representative of forage zooplankton – Acartia (Acartiura) clausi Giesbrecht, 1889 and two thermophilic species of Calanoida – Acartia (Acanthacartia) tonsa Dana, 1849 and Centropages ponticus Karavaev, 1895. In Ukrainian waters average abundance and biomass of zooplankton in 2019 was similar to those in 2016 and much higher than in 2017. Dominant taxa and spatial distribution of zooplankton in 2019 were similar to those in 2016 and 2017. Average biomass of forage zooplankton in 2019 was approximately 10 times higher than in 2016 and 2017. In the Georgian coastal waters annual average abundance and biomass of mesozooplankton decreased, due to a sharp decline in the abundance of Noctiluca scintillans (Macartney) Kofoid & Swezy, 1921. It was found that at most of the stations the dominant role in the formation of zooplankton biomass was played by the organisms of forage zooplankton. By the IZI index, the subdivision Northwestern Black Sea Bays had “Good”, “Poor” and “Moderate” water quality in spring, summer and autumn respectively. The subdivision’s deepwater shelf and shallow shelf had “Bad” water quality. The subdivision Danube-Dnieper interfluve coastal waters had “High” water quality. The Danube Avandelta area had “High”, “Good” and “High” water quality in spring, summer and autumn respectively. The best ecological class status was in 2019 and the worst – in 2016. The main tendencies in changes in the mesozooplankton community in the Black Sea are decrease in the percentage of N. scintillans in the total zooplankton biomass and increase in the percentage of Copepoda. Those tendencies indicate decrease in the pressure of the negative eutrophication factor and show positive changes in the forage base of commercial planktophagous fish and the ecological status of the Black Sea waters.

Numerical Study on the Effects of Water Surface Shield and Oxygen Injection on Water Quality in Lake Biwa

2008 ◽  
Author(s):  
Daisuke Kitazawa ◽  
Michio Kumagai
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Water Surface ◽  
Lake Biwa ◽  
Vertical Mixing ◽  
Three Dimensional ◽  
Coupled Model ◽  
Floating Platform ◽  
Oxygen Injection ◽  
Water Bottom

Numerical simulation was carried out by means of a three-dimensional hydrostatic and ecosystem coupled model in order to predict the effects of water surface shield and oxygen injection on the water quality in Lake Biwa. Recent observations show the degradation of water quality particularly around the water bottom in Lake Biwa. One of the possible reasons of the degradation is the depletion in the vertical mixing of waters due to climate change. The meteorological observations at Hikone show that the atmospheric temperature has increased by 1°C in the recent 20 years. If the vertical mixing of waters is weakened, the waters with rich oxygen are not supplied enough around the water bottom during winter seasons, and the concentration of dissolved oxygen is hardly recovered to the saturated level. The depletion in the vertical mixing of waters has been increasingly worried since Intergovernmental Panel on Climate Change (2007) reported that the globally mean atmospheric temperature will increase by a few °C in a century. In order to cope with such problems, the present study proposes a feasible system to inject the oxygen produced by the electrolysis of water. In the proposed system, water surface is shielded by a floating platform, which blocks off the penetration of solar radiation through the water surface and generates the density-driven current due to the horizontal difference in water temperature. In addition, solar cell modules are installed on the floating platform to produce oxygen by means of the electrolysis of water. The produced oxygen is then released from the electrodes installed around the water bottom. As a result of numerical simulation using the three-dimensional hydrostatic and ecosystem coupled model, the effect of water surface shield was negligible since the surface area of the floating platform was quite smaller than that of Lake Biwa. The effect of oxygen injection was remarkable and localized in summer than in winter. The concentration of dissolved oxygen was then expected to increase by more than 0.2mg/l within 15m from the bottom surface in summer, in the cases when 730,000m3 of oxygen was injected in an year. The effect of seasonal change in the production of oxygen was negligible since little difference was found in the concentration of dissolved oxygen. As future studies, the nested grid system should be utilized to predict precisely the diffusion of oxygen both in the vicinity of the electrode and in the whole Lake Biwa.

scholarly journals Innovative Water Quality and Ecology Monitoring Using Underwater Unmanned Vehicles: Field Applications, Challenges and Feedback from Water Managers

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1196 ◽  
Author(s):  
Rui L. Pedroso de Lima ◽  
Floris C. Boogaard ◽  
Rutger E. de Graaf-van Dinther
Keyword(s):  
Water Quality ◽  
Single Point ◽  
Three Dimensional ◽  
Ecological Status ◽  
Water Systems ◽  
Unmanned Vehicles ◽  
Dynamic Monitoring ◽  
Spatial And Temporal Variability ◽  
Monitoring Methods ◽  
Local Water

With climate change and urban development, water systems are changing faster than ever. Currently, the ecological status of water systems is still judged based on single point measurements, without taking into account the spatial and temporal variability of water quality and ecology. There is a need for better and more dynamic monitoring methods and technologies. Aquatic drones are becoming accessible and intuitive tools that may have an important role in water management. This paper describes the outcomes, field experiences and feedback gathered from the use of underwater drones equipped with sensors and video cameras in various pilot applications in The Netherlands, in collaboration with local water managers. It was observed that, in many situations, the use of underwater drones allows one to obtain information that would be costly and even impossible to obtain with other methods and provides a unique combination of three-dimensional data and underwater footage/images. From data collected with drones, it was possible to map different areas with contrasting vegetation, to establish connections between fauna/flora species and local water quality conditions, or to observe variations of water quality parameters with water depth. This study identifies opportunities for the application of this technology, discusses their limitations and obstacles, and proposes recommendation guidelines for new technical designs.

scholarly journals Grazing Potential—A Functional Plankton Food Web Metric for Ecological Water Quality Assessment in Mediterranean Lakes

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1274 ◽  
Author(s):  
Georgia Stamou ◽  
Matina Katsiapi ◽  
Maria Moustaka-Gouni ◽  
Evangelia Michaloudi
Keyword(s):  
Water Quality ◽  
Quality Assessment ◽  
Secchi Depth ◽  
Ecological Status ◽  
Fish Predation ◽  
Water Quality Assessment ◽  
Zooplankton Biomass ◽  
Ecological Water Quality

Grazing potential (GP, in % day−1) was estimated for the plankton communities of 13 Greek lakes covering the trophic spectrum, in order to examine its sensitiveness in discriminating different classes of ecological water quality. Lakes with high GP values exhibited high zooplankton biomass dominated by large cladocerans or/and calanoids while lakes with low GP values had increased phytoplankton biomass and/or domination of small-bodied zooplankton indicating intensive fish predation. GP successfully distinguished among ecological water quality classes (estimated using the phytoplankton water quality index PhyCoI) indicating its potential use as a metric for ecological water quality assessment. As a next step, PhyCoI index was modified to include GP as a metric in order to enhance the phytoplankton-based ecological status classification of lakes incorporating zooplankton as a supporting factor. The PhyCoIGP successfully assessed the ecological water quality in accordance with PhyCoI classification whereas it was significantly correlated with the eutrophication proxy TSISD based on Secchi Depth. Thus, we propose to use the modified phytoplankton index PhyCoIGP for monitoring the ecological water quality of lakes.

A Real-Time Mathematical Model for Three-Dimensional Tidal Flow and Water Quality

1991 ◽  
Vol 24 (6) ◽  
pp. 171-177 ◽  
Author(s):  
Zeng Fantang ◽  
Xu Zhencheng ◽  
Chen Xiancheng
Keyword(s):  
Mathematical Model ◽  
Water Quality ◽  
Real Time ◽  
Control Volume ◽  
Tidal Flow ◽  
Three Dimensional ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Practical Application ◽  
The Pearl River

A real-time mathematical model for three-dimensional tidal flow and water quality is presented in this paper. A control-volume-based difference method and a “power interpolation distribution” advocated by Patankar (1984) have been employed, and a concept of “separating the top-layer water” has been developed to solve the movable boundary problem. The model is unconditionally stable and convergent. Practical application of the model is illustrated by an example for the Pearl River Estuary.

scholarly journals Assessment of the Impact of Small Hydropower Plants on the Ecological Status Indicators of Water Bodies: A Case Study in Lithuania

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 433
Author(s):  
Laima Česonienė ◽  
Midona Dapkienė ◽  
Petras Punys
Keyword(s):  
Water Quality ◽  
Benthic Macroinvertebrates ◽  
Suspended Solids ◽  
Ecological Status ◽  
Fish Abundance ◽  
Water Bodies ◽  
Small Hydropower ◽  
Hydropower Plants ◽  
Physico Chemical ◽  
The Impact

Hydropower plants produce renewable and sustainable energy but affect the river’s physico-chemical characteristics and change the abundance and composition of the aquatic organisms. The impact of large HPPs on the ecological conditions of surface water bodies have been extensively studied, but less attention has been paid to environmental impact studies of small hydropower plants (SHPs). The impact of hydropeaking on both the river flow regime and ecosystems has been well-studied for peaking mode plants, mainly medium to large-sized ones. However, for small hydroelectric power plants, and especially for those in lowland rivers, the available information on water quality, benthic macroinvertebrates communities and fish abundance, and biomass is not sufficient. Ten small hydropower plants were selected, and the ecological status of water bodies was assessed in different parts of Lithuania. The studies were performed at the riverbed upstream from the SHPs, where the hydrological regime has not changed, and downstream from the SHPs. It was found that the small hydropower plants do not affect the physico-chemical values of the water quality indicators. This study demonstrated that the total number of benthic macroinvertebrates taxa (TS) is influenced by the concentration of nitrogen and suspended solids, the water flow, the river area, and the current speed; the number of EPT (Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies)) taxa is influenced by the concentration of nitrogen and suspended solids. The studied indicators do not have a significant impact on biomass. The SHPs affect the fish abundance and biomass. The Lithuanian fish index (LFI) is influenced by the average depth and area of the river. Some SHPs operating in lowland areas may yield somewhat significant hydrograph ramping but more detailed investigation is needed to support the significance of this impact on the biological indices.

Developing a Cloud-based Toolbox for Sensitivity Analysis of a Water Quality Model

2021 ◽  
pp. 105068
Author(s):  
Soobin Kim ◽  
Yong Sung Kwon ◽  
JongChel Pyo ◽  
Mayzonee Ligaray ◽  
Joong-Hyuk Min ◽  
...  
Keyword(s):  
Water Quality ◽  
Sensitivity Analysis ◽  
Water Quality Model ◽  
Quality Model

scholarly journals Mixtures of chemicals are important drivers of impacts on ecological status in European surface waters

2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Leo Posthuma ◽  
Werner Brack ◽  
Jos van Gils ◽  
Andreas Focks ◽  
Christin Müller ◽  
...  
Keyword(s):  
Water Quality ◽  
Quality Management ◽  
Surface Waters ◽  
Water Quality Management ◽  
Ecological Status ◽  
Ecological Impacts ◽  
Chemical Pollution ◽  
Individual Species ◽  
Integrated Analysis ◽  
Chemical Mixtures

Abstract The ecological status of European surface waters may be affected by multiple stressors including exposure to chemical mixtures. Currently, two different approaches are used separately to inform water quality management: the diagnosis of the deterioration of aquatic ecosystems caused by nutrient loads and habitat quality, and assessment of chemical pollution based on a small set of chemicals. As integrated assessments would improve the basis for sound water quality management, it is recommended to apply a holistic approach to integrated water quality status assessment and management. This allows for estimating the relative contributions of exposure to mixtures of the chemicals present and of other stressors to impaired ecological status of European water bodies. Improved component- and effect-based methods for chemicals are available to support this. By applying those methods, it was shown that a holistic diagnostic approach is feasible, and that chemical pollution acts as a limiting factor for the ecological status of European surface waters. In a case study on Dutch surface waters, the impact on ecological status could be traced back to chemical pollution affecting individual species. The results are also useful as calibration of the outcomes of component-based mixture assessment (risk quotients or mixture toxic pressures) on ecological impacts. These novel findings provide a basis for a causal and integrated analysis of water quality and improved methods for the identification of the most important stressor groups, including chemical mixtures, to support integrated knowledge-guided management decisions on water quality.

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