Ecosystem Quality Research Articles

Nature-Based Solutions vs. Human-Induced Approaches for Alpine Grassland Ecosystem: “Climate-Help” Overwhelms “Human Act” to Promote Ecological Restoration in the Three-River-Source Region of Qinghai–Tibet Plateau

How climate change and human activities drive the evolution of the regional environment and where the quality of ecosystems improve or decline over time have become widespread concerns. In this study, we took the Three-River-Source (TRS) region of the Qinghai–Tibet Plateau as a case, aiming to identify and quantify the contribution of the natural and anthropogenic factors to the ecosystem changes over the past years from 1980 to 2018 using the methods of remote sensing and spatial statistical analysis. Based on the land cover map interpreted by reference to satellite remote sensing imagery data, we defined the Ecological Restoration Area Proportion (ERAP) as the bare land patch decrement to indicate the ecologically restored quantity in space. Assembling the restoration project information, we digitalized and vectorized the ecological Restoration Intensity (RI) including the spatial range and temporal duration. Combining the ERAP and the net primary productivity (NPP), which indicates the quantity and quality of ecosystems, respectively, the ecological asset Index (EAI) was developed and calculated. Having integrated the datasets of the vegetation monitoring, climatic factors, geographical factors, and human activities, we performed multi-variable analysis of the attribution of how the change in the EAI, the NPP, and the EAI have been affected by these factors together. The NPP of the middle and eastern parts of the TRS region has improved the most, as the average growth rate of NPP reached approximately 2.5 kg C/m2/10a. Due to such dynamic pattern, we found that human-induced re-vegetation has made limited contributions in our multi-regression model as the variance explained by the RI merely amounts to 4.4% to 8.8%, while the changes were mostly dependent on the regional temperature and the precipitation which contributed over 45% to the ecological restoration on average. It was summarized that “climate-help” overwhelms “human act” in such alpine grassland ecosystem. The regression results for the different aspects of the ERAP and NPP demonstrated that the ecological restoration project helped most in regard to ecosystem quality improvement rather than the restored ecosystem quantity. Our study has developed a comprehensive assessment methodology that can be reused to account for more ecological asset. The case is an example of an alpine ecosystem in which the success of ecological restoration needs favorable climatic conditions as supporting evidence for the nature-based solution.

Ecosystem functions of ants and dung beetles in agriculture‐dominated Amazonian riparian forests

Abstract Land‐use changes and habitat fragmentation can alter biodiversity and associated ecosystem functions. We investigated whether cropland expansion in south‐east Amazonia decreases ecosystem functions performed by ants and dung beetles by altering their communities. We sampled both groups in two forest types, in south‐eastern Amazonia: undisturbed riparian forests and riparian forests surrounded by croplands. We sampled ants and dung beetles with epigaeic pitfall traps, and experimentally assessed seed removal and predation by ants, and faeces and seed removal by dung beetles. Although ant and dung beetle abundance and richness did not differ across riparian forests, species composition of both groups did. Ants found seeds faster in undisturbed riparian forests, but the proportion of seed removal did not differ between forests. The abundance of predatory ants and the predation of termites by ants did not differ between forests. Seed and dung removal by dung beetles did not differ across riparian forests. Despite the observed differences in dung beetle composition, we did not find the effects on ecosystem functions probably due a functional redundancy of species. The quality of ecosystem functions provided by ants is lower in riparian forests surrounded by croplands, while changes in dung beetle diversity did not impact their ecosystem functions, with potential effects on the natural recovery of these disturbed riparian forests.

Quantifying ecosystem quality in the Tibetan Plateau through a comprehensive assessment index

The Tibetan Plateau, characterized by complicated geological structures, is sensitive to climate change and human activities. The vulnerable environmental balance of the Tibetan Plateau has witnessed substantial alterations, emphasizing the urgency to comprehend and protect its ecosystem quality. In this study, we aim to quantify the ecosystem quality of the Tibetan Plateau, portray its spatiotemporal dynamics, and analyze the spatial heterogeneity of climatic and anthropogenic influences. We employed the entropy weight method (EWM) to construct a comprehensive index, termed the Ecosystem Quality Comprehensive Assessment Index (EQCAI). The historical spatiotemporal patterns and trends of EQCAI were subsequently identified. Our results revealed a gradient of decreasing ecosystem quality from the southeast to the northwest of the Tibetan Plateau, while the mitigation of ecosystem quality degradation displayed an improving trend from the southwest to the northeast. We further detected the spatial heterogeneity of factors influencing changes in ecosystem quality through the multiscale geographically weighted regression (MGWR) method. Precipitation emerged as the primary positive factor, exerting a profound influence on the ecosystem quality of the southeastern Tibetan Plateau. Conversely, evapotranspiration, elevation, and human activities negatively affected the western Tibetan Plateau. This study proposes targeted conservation efforts for forestry regions with high ecosystem quality in the southeastern Tibetan Plateau. Additionally, we suggest that the positive impact of human activities on the ecosystem quality of the Tibetan Plateau should be further strengthened. Our findings contribute valuable insights for informed decision-making in the sustainable management and preservation of the Tibetan Plateau's fragile ecosystem.

Local terrestrial biodiversity impacts in life cycle assessment: A case study of sedum roofs in London, UK

AbstractUrban development is a key driver of global biodiversity loss. “Green” infrastructure is integrated to offset some impacts of development on ecosystem quality by supporting urban biodiversity, a prominent example being green roofs. The effects of green infrastructures on urban biodiversity are not well understood and poorly included in life cycle assessment (LCA) methodology. Here, we present a novel methodology that quantifies the local impact of green infrastructures on terrestrial biodiversity—demonstrated here for sedum roofs in London, UK—and integrates within LCA. It relates energy provision by plants to the metabolic requirements of animals to determine what species richness (number of species) and species abundance (number of individuals) are supported. We demonstrate this methodology using a case study, comparing the life cycle impact of developing 18 buildings, with either asphalt concrete or sedum roofs, on ecosystem quality. We found the sedum roofs (0.018 km2) support 53 species (673 individuals), equivalent to 1.3% of the development's life cycle impacts on ecosystem quality. Complete offsetting requires considerable reduction in transport use throughout the development's lifetime, and lower environmental impact material selection during construction (contributing 98% and 2%, respectively). The results indicate sedum roofs offer minor impact mitigation capacities in the context of urban development, and this capacity is limited for all green infrastructures by species richness in local species pools. This paper demonstrates the potential and limitations of quantifying terrestrial biodiversity offsets offered by green infrastructures alongside urbanization, and the need for realistic expectations of what role it might play in sustainable urban design.

Role of three-dimensional vortex motions on horizontal eddies in an open-channel cavity

AbstractLateral cavities are a popular object of study in hydraulic research as they are widely found in rivers and hydraulic facilities and significantly impact flow patterns, sediment transport, and water quality in aquatic ecosystems. While the effects of open-channel cavities on various aspects including characteristics of three-dimensional structures have been extensively studied, the role of vertical flow structures in the cavity has not been focused on. This study examines the relationship between the shallowness parameter and the three-dimensional flow effects on the dynamics of an open-channel lateral cavity flow with horizontal vortex motion, comparing the conventional two-dimensional model (2DC), advanced depth-integrated models including general bottom velocity calculation method (GBVC) with the ability to consider vertical flow structures, simplified bottom velocity calculation method with the shallow water assumption (SBVC), a three-dimensional model (3DC), and experimental data. The comparison results demonstrate that the three-dimensional flow effect significantly impacts the velocity distribution and vortex evolution in the cavity. The GBVC model demonstrates a good agreement with the flow patterns by the 3DC model and experimental results in the cavity, whereas the 2DC and SBVC models are unsuitable for deep-water conditions.

Thermal and environmental analysis of an infectious medical waste-to-energy

This work presents an infectious medical waste-to-energy (IMWtE) thermal and environmental analysis using combined heat and power (CHP) technology. Steam sterilization can be operated with an infectious medical waste (IMW) of 375 kg/h⋅unit, a maximum per day of 12,000 kg/day for double sterilization units, and a running time of 16 h/day. The CHP system uses a dried IMW of 797 kg/h, generating a power output of 128.98 kWe, providing a drying heat of 382.91 kW, and achieving an overall system efficiency of 8.45 %. Results are obtained for a life cycle assessment (LCA) of the IMWtE by CHP system technology. The endpoint effectiveness comprises considerations of human health: 2.83E+01 DALY, ecosystem quality is represented value of: 9.32E+00 Species⋅y, and natural resource value of: 1.08E+06 USD, all of these are fundamentally linked to the utilization of steel, copper, paint, and gypsum. The LCA impacts are primarily due to the operation phase (93 %), with the smaller contribution of the decommissioning phase (4 %), and the construction phase (3 %), respectively.

Dissolved organic matter (DOM) is independently stratified in thermally stratified water bodies

Thermal stratification often occurs in deep-water bodies, including oceans, lakes, and reservoirs. Dissolved organic matter (DOM) plays a critical role in regulating the dynamics of aquatic food webs and water quality in aquatic ecosystems. In the past, thermal stratification boundaries have been sometimes used exclusively to analyze the vertical distribution of DOM in thermally stratified water bodies. However, the validity of this practice has been challenged. Currently, there is limited understanding of the formation mechanism and stratification of the vertical distribution of DOM in thermally stratified water bodies, which hinders the analysis of the interactions between DOM and vertical aquatic ecological factors.To address this gap, we conducted a comprehensive study to extensively collect the vertical distribution of DOM in thermally stratified water bodies and identify the primary factors influencing this distribution. We found that DOM was independently stratified in thermally stratified water bodies (including two cases in unstratified water bodies), and that the formation mechanisms and statuses of DOM stratification were different from those of thermal stratification. The boundaries and numbers of DOM stratification were generally inconsistent with those of thermal stratification. Therefore, it is more accurate to divide DOM into different layers according to its own vertical profile, and analyze DOM characteristics of each layer based on its own stratification instead of thermal stratification. This study sheds light on the relationship between DOM and thermal stratification and provides a novel approach for analyzing DOM vertical distribution characteristics and their impact on aquatic ecosystems. This finding also holds significant implications for the design and implementation of environmental management programs aimed at preserving the health and functionality of aquatic ecosystems.

Analysis of Physico-Chemical Factors of Ramganga River Water in Bareilly District

The systematic study was carried out to determine the physico-chemical parameters of water samples of Ramganga River in Bareilly district. The rivers are an essential water resource and used for several purposes. The water quality of all fresh water ecosystems is assessed by the physico-chemical. Water samples were collected from 3 sites along the river and analyzed using standard methods in laboratory. The physico-chemical characteristics were studied and analyzed for a period of 6 months from April 2022 to September 2022. Various physico-chemical parameters such as Temperature, PH, transparency, total dissolved solids, total suspended solids, DO, FCO2, Carbonates, Bicarbonates, chlorides, Calcium, Magnesium, Total hardness of lake were estimated throughout the year.

Boon and burden: economic performance and future perspectives of the Venice flood protection system

Sea-level rise (SLR) and flooding are among the climate change stressors challenging human society in the twenty-first century. Many coastal areas and cities are implementing innovative solutions to mitigate flood risks and enhance resilience. Venice has recently developed a system of storm surge mobile barriers, known as the MoSE (Modulo Sperimentale Elettromeccanico or Experimental Electromechanical Module). This study aims to investigate the economic viability of MoSE operations in light of the potential future evolution of SLR. To conduct a cost-benefit analysis, a system dynamics model is utilised to assess the impact of MoSE operations on economic and residential activities of Venice and its port. Simulations are conducted until the end of the century, considering two SLR scenarios. The results suggest that the economic benefits largely outweigh the combined costs of investment and foregone port revenues resulting from the MoSE closures. Nevertheless, the increasing number of closures due to SLR seriously challenges the viability of the infrastructure in the medium to long term. Even more importantly, very frequent closures will have serious impacts on the quality of the lagoon ecosystem. These findings suggest a revision and stronger integration of the city’s safeguarding strategies, including the increase of the MoSE closure level officially set at 110 cm, and other coordinated interventions, such as sewer system consolidation.

Riparian habitat connectivity restoration in an anthropized landscape: A multi-species approach based on landscape graph and soil bioengineering structures.

In urbanized areas, rivers and riparian ecosystems are often the only ecological corridors available for wildlife movement. There, riverbanks are often stabilised by civil engineering structures (dykes, riprap). This can lead to habitat degradation and loss of landscape connectivity. Fascines (willow bundles tied together) could be an alternative to riprap, since they maintain the quality of the natural ecosystems by using native vegetal species instead of rocks, but their potential positive impact needs to be assessed. We proposed a landscape-scale decision-making method for river managers who want to restore banks by transforming riprap into fascines to improve landscape connectivity. We applied our methodology to a case study involving a 25 km-stretch of the Arve River, France. We selected four target vertebrate species based on biological traits to cover a wide range of dispersal capacities. For each species, we used landscape graphs to assess habitat connectivity under different contrasted riverbank scenarios. Scenarios included replacing all-natural banks with ripraps or replacing all ripraps with fascines. In addition, we systematically tested the effect of replacing individual 100 or 500 m sections of ripraps by fascines, to locate where riverbank restoration would maximize connectivity gain. The four species selected responded very differently to the scenarios (up to +14% and +46% change in Probability of Connectivity for common toads and Eurasian beavers, respectively, 0% for common sandpipers and barred grass snakes). The restoration of specific riverbank sections could result in important gains in PC (up to +33% for one single section for one species) but no section maximized connectivity gain for all the target species.

Assessing the quality of mangrove ecosystem as breeding sites organisms in the coastal area

Assessing the quality of mangrove ecosystem as breeding sites organisms in the coastal area

ANALYSIS OF THE FACTORS CONTRIBUTING TO ENVIRONMENTAL POLLUTION IN THE SUBCARPATHIAN PROVINCE

The work presents an examination of Poland's environmental condition, with a focus on the contamination of air and surface waters by various chemical elements. The composition and quality of the air impact ecosystems, plant growth, the animal kingdom, and shape human living conditions. These factors play a significant role in driving global climate change. The repercussions of air pollution encompass phenomena such as smog, acid rain, ozone layer depletion, as well as impacts on industrial and municipal facilities, contributing to global warming. The article conducts an analysis of air pollution, surface water contamination, and electromagnetic radiation pollution in Subcarpathian, utilizing the city of Stalowa Wola and the Stalowa Wola county as case studies. This choice is informed by the fact that Stalowa Wola stands as one of the largest industrial cities in the Subcarpathian Voivodeship, suggesting that environmental pollution levels in this county might surpass those in other regions. The article also delineates the features of air and surface water pollution, along with electromagnetic radiation characteristics. It scrutinizes pollution sources in the mentioned county, explicates the causes of such pollution, and proposes strategies for environmental amelioration. The analysis of the environmental status of Stalowa Wola county during the years 2018 to 2020 is presented, accompanied by recommendations for initiatives that could enhance its condition. The research findings indicate that the condition of uniform segments of surface waters, as evaluated through conducted studies, is deemed poor. The discharge of wastewater from specific pollution points, particularly wastewater from municipal origins, emerges as the predominant cause of subpar water quality.

Sustainability analysis of primary wastewater treatment by willow plantations in Québec

Wastewater treatment is a necessary step to avoid environmental impacts of water consumption and usage. Traditional approaches are expensive and are limited to developed countries. Phytofiltration using fast-growing trees and shrubs like willows potentially offer an alternative. This paper aims to determine if wastewater treatment using phytofiltration can provide complementary environmental and economic benefits for rural communities in a Nordic climate such as the province of Québec, Canada. It looks at different perspectives of the wastewater treatment solution in a local and rural context. Based on life cycle analysis (LCA) and life cycle cost analysis (LCC), we found that, for an exemplar Québec municipality, the conventional wastewater treatment scenario impacted more on climate change, ecosystem quality and human health than the two phytofiltration of wastewater scenarios studied, where impact is highly dependant on the biomass valorization. The net present cost of the phytofiltration scenarios were lower than typical conventional treatment in Québec. For a biomass producer, conventional biomass production had the highest environmental impact on ecosystem quality, while biomass production from phytofiltration had the highest environmental impact on climate change, human health, and resources. We demonstrate that the phytofiltration is a viable and multifunctional technology that could provide good incentives for a local biomass value chain. it allows to both alleviate wastewater treatment burden and provide affordable biomass for bioenergy development for rural communities. Mobilizing local stakeholders will be key to make phytofiltration an alternative solution for both environmental burden alleviation and rural economic development.

ANÁLISE DE ESTRATÉGIAS DE GESTÃO DO ECOSSISTEMA DO LAGO TONDANO NO NORTE SULAWESI, INDONÉSIA USANDO MÉTODOS SWOT E AHP

Purpose: The study aimed to analyze strategies for managing the ecosystem of Lake Tondano to prepare a medium-term plan for its management. Theoretical Framework: The Lake Tondano ecosystem has important economic and ecological functions for the economy and welfare of the people in North Sulawesi Province. The quality of the lake ecosystem continues to decline including water pollution, siltation of the lake, shrinkage of the area and other uses that do not consider aspects of ecosystem sustainability. Method: The analysis method used a combination of SWOT and AHP, with stakeholder participation. Data was obtained through literature study and focus group discussions (FGD) involving both formal and informal stakeholders. Results: The AHP analysis results indicate that simultaneous impact criteria are the main criteria for determining priority strategies. Conclusions: Thirteen strategies were formulated based on the SWOT analysis. The medium-term plan's management priority strategies have been determined based on the results of the AHP analysis. These strategies include: (1) Controlling the level of water pollution and household waste, (2) Revitalizing the lake, (3) Developing institutions for integrated lake ecosystem management, and (4) Planning the spatial layout of the lakes and their boundaries.

Modeling pH changes and electrical conductivity in surface water as a result of mining activities

Purpose. To develop comprehensive models for predicting the pH and electrical conductivity of surface water in Maiganga coal mine and environs affected by mining activities. Methodology. The research utilizes a combination of in-situ measurement, laboratory analysis, modeling technique using Ansys Workbench and Linear Regression for predicting the content of pollutants. In-situ measurement/data collection in the upstream and downstream were carried out to evaluate the potential impact of mining activities on surface and ground water quality. Electrical conductivity and pH were measured on the samples that were collected using Oakton 5/6 pH meter and TDS/EC meter. Findings. According to the results, the regression statistics model of pH and electrical conductivity (EC) shows that the predicted values have a pH range of 4.7–7.05 and a mean pH value of 5.5. In contrast, while the EC ranges from 454.52 to 2,720.68 s/cm (EC) with a mean value of 905 µs/cm of the downstream flow which is completely dependent on the mine inlet (pH-in and EC-in). The findings show a direct correlation between surface water pH, electrical conductivity, and mining activities in the Maiganga coal mine area and their detrimental effects on the ecosystem and water quality. Originality. The results were obtained directly from the mine site during field visit and can be compared to data from active coal mine sites. Practical value. The detrimental effect of the results of mining activities can be controlled if monitoring sensors are introduced at mines’ effluent outlet to alert the mine management of possible danger in real time.

Butterfly Abundance and Diversity in Different Habitat Types in the Usangu Area, Ruaha National Park

Insects are key fauna species that respond quickly to disturbances and environmental changes. They act as good indicators of habitat, community, or ecosystem quality. Among the great diversity of insects, butterflies stand as ideal bio-indicators for ecosystem function and are sensitive to changes in habitat composition and structure. This study was carried out to examine the diversity and abundance of butterflies across the restored habitats in Usangu area part of Ruaha National Park (RUNAPA) from May 2022 to June 2022 using the walking transect method supplemented by sweep nets and butterfly baited traps. A total of six transects of 1 km in length were laid in the four main habitat types selected in Usangu area including grassland, Miombo woodland, Vachellia/Commiphora woodland, and riverine forest. Searches were conducted in the morning and evening. The Miombo woodland and riverine forest habitats exhibited relatively higher species diversity, richness, evenness, abundance, and a higher number of habitat-restricted species, while Vachellia/Commiphora woodland and grassland habitats recorded the lowest diversity and abundance as well as the lowest number of habitat-restricted species. Family Nymphalidae was the most dominant followed by Pieridae while Papilionidae and Hesperiidae were scarce in the study area. This study clearly shows the importance of Miombo woodland and riverine forest habitats in sustaining rich butterfly diversity and abundance in Usangu area. The two habitats must be effectively managed and conserved for sustaining ecological health and integrity of Usangu area. The Usangu area’s Miombo woodland and riverine forest habitats have immense potential for butterfly tourism and they can offer an excellent opportunity to promote conservation efforts and raise public awareness. However, it is crucial to monitor these habitats closely as any environmental changes that may occur could harm the butterfly diversity and abundance in the area. Preserving this wilderness to maintain a thriving butterfly population is of utmost importance.

Dissolved Oxygen Forecasting for Lake Erie’s Central Basin Using Hybrid Long Short-Term Memory and Gated Recurrent Unit Networks

Dissolved oxygen (DO) concentration is a pivotal determinant of water quality in freshwater lake ecosystems. However, rapid population growth and discharge of polluted wastewater, urban stormwater runoff, and agricultural non-point source pollution runoff have triggered a significant decline in DO levels in Lake Erie and other freshwater lakes located in populated temperate regions of the globe. Over eleven million people rely on Lake Erie, which has been adversely impacted by anthropogenic stressors resulting in deficient DO concentrations near the bottom of Lake Erie’s Central Basin for extended periods. In the past, hybrid long short-term memory (LSTM) models have been successfully used for the time-series forecasting of water quality in rivers and ponds. However, the prediction errors tend to grow significantly with the forecasting period. Therefore, this research aimed to improve the accuracy of DO forecasting models by taking advantage of Lake Erie’s real-time water quality (water temperature and DO concentration) monitoring network to establish temporal and spatial links between adjacent monitoring stations. We developed hybrid LSTM models that combine LSTM, convolutional neuron network LSTM (CNN-LSTM), hybrid CNN with gated recurrent unit (CNN-GRU) models, and convolutional LSTM (ConvLSTM) to forecast near-bottom DO concentrations in Lake Erie’s Central Basin. These hybrid LSTM models improve their capacity to handle complicated datasets with spatial and temporal variability. These models can serve as accurate and reliable tools for forecasting DO concentrations in freshwater lakes to help environmental protection agencies better access and manage the health of these vital ecosystems. Following analysis of a 21-site Lake Erie dataset for 2020 and 2021, the ConvLSTM model emerged as the most accurate and reliable, boasting an MSE of 0.51 mg/L, MAE of 0.42 mg/L, and an R-squared of 0.95 over the 12 h prediction range. The model foresees future hypoxia in Lake Erie. Notably, the temperature near site 713 holds significance for Central Basin DO forecasting in Lake Erie, as indicated by outcomes derived from the Shapley additive explanations (SHAP).

Influence of mangrove ecosystem quality degradation on long-tailed monkey population in Muara Angke wildlife sanctuary Jakarta

Influence of mangrove ecosystem quality degradation on long-tailed monkey population in Muara Angke wildlife sanctuary Jakarta

Assessing the Environmental Impact of Aircraft Maintenance

This study intends to investigate the maintenance of the sample aircraft under C-check with the environmental impact approach. With this research, maintenance of both aircraft types is divided into related subsystems and total process hours are determined in man-hours. Thus, it is aimed to show that environmental impacts should be taken into consideration in maintenance planning. The environmental effects that occur during aircraft maintenance operations are analysed. Environmental impact analysis, a basic life cycle analysis, is conducted under ISO 14044. Impacts (Impact on Human Health, Impact on Ecosystem Quality Impact and Resources Impact) have been calculated according to the Eco-Indicator99 database using SimaPro, which is the Life Cycle Analysis program. In the light of all results, it is seen that the C-check for Boeing 737 has a significant negative impact on the resources, ecosystem quality, and human health especially in all ATA100 categories.

Composition and Distribution of Microeukaryotic Communities in the Surface Sediments of Five Geographic Regions of Bohai Sea Based on 18S rDNA Amplicon Sequencing

The Bohai Sea is a semi-enclosed shallow water that is influenced by both natural and anthropogenic stressors. However, the microeukaryotic communities and environmental factors that affect them in different regions remain largely unclear. We investigated microeukaryotic communities in surface sediments from five geographic regions using high-throughput sequencing of the 18S rDNA gene. The Miaodao Archipelago, Yellow River Estuary, and Central Bohai Sea had the highest Shannon and Simpson indices of the eukaryotic communities, while the Yellow River Estuary exhibited the highest Chao1 index. The microeukaryotic communities in surface sediments were mainly composed of Dinoflagellata, Bacillariophyta, Ciliophora, Cercozoa, and Protalveolata. Thalassiosira has a relatively high abundance at the Liaodong Bay and Central Bohai Sea, possessing the proportion of 41.70% and 38.10%, respectively, while Gonyaulax was the most abundant taxa in the Bohai Bay, occupying a proportion of 57.77%. Moreover, a negative correlation between diatoms and dinoflagellates was observed. Phosphorus, nitrogen, salinity, temperature, and silicate were major environmental determinants of microeukaryotic composition. Microeukaryotic communities in the surface sediments, especially for the composition and ratio of diatoms to dinoflagellates, reflected the environmental quality of marine ecosystems. Overall, these microeukaryotic community compositions provide a reliable indicator for monitoring the level of marine eutrophication in the Bohai Sea.