Shallow lakes provide vital ecological services yet face escalating threats from climate warming, eutrophication, and imidacloprid pollution. Understanding how these stressors individually and interactively impact phytoplankton—the cornerstone of aquatic food webs—is critical for ecosystem health. Through an 8-month, multi-seasonal mesocosm experiment, we assessed the individual and combined effects of these stressors on phytoplankton biomass and community structure and diversity. We found that nutrients and imidacloprid, individually and combined, increased total phytoplankton biomass while favoring Cyanobacteria (dominant: Microcystis aeruginosa) and Chlorophyta. Crucially, despite imidacloprid-induced suppression of their primary copepod grazers, Bacillariophyta (diatom) biomass declined disproportionately due to their lack of direct abiotic benefits or compensatory mechanisms, coupled with intensified competition from cyanobacteria that gained multifaceted advantages. Bacillariophyta exhibited unique vulnerability, with severe species losses under imidacloprid, contrasting sharply with cyanobacterial resilience. Warming, imidacloprid, and their combination reduced total species richness, while all single stressors decreased Shannon diversity and equitability. While individual stressors significantly impacted phytoplankton communities, their combined effects did not consistently exacerbate these impacts and frequently mitigated—or even reversed—the direction of negative effects induced by individual stressors, particularly those from imidacloprid exposure. This study underscores that environmental risk assessments must avoid overestimating individual stressors in lake ecosystems subject to multiple pressures. Concurrently, it highlights the necessity of prioritizing monitoring differential phytoplankton groups (particularly vulnerable Bacillariophyta versus resilient Cyanobacteria). Such approaches are critical to developing targeted management strategies, accurately projecting ecological trajectories of phytoplankton communities, and ultimately safeguarding the sustainable health of shallow lake ecosystems.

Climate warming and eutrophication are reshaping greenhouse gas (GHG) emissions from shallow lakes, yet how different warming regimes interact with phosphorus enrichment remains poorly understood. Here, we conducted a year-long experiment using shallow-lake mesocosms planted with aquatic macrophytes to compare constant warming (a sustained 4°C increase) with variable warming (the same mean warming combined with short-term temperature fluctuations), together with phosphorus enrichment. Responses differed markedly among gases. Warming reduced annual CO2 emissions, primarily through indirect changes in macrophyte communities and water chemistry. In contrast, warming increased CH4 emissions mainly through direct thermal effects, although the increase was smaller under variable than under constant warming, reflecting distinct shifts in macrophyte functional composition under the two warming regimes. N2O fluxes were largely insensitive to warming but responded primarily to phosphorus enrichment, which shifted the system from a net annual source to a sink. These findings demonstrate that greenhouse-gas responses to global change cannot be generalized across gases and highlight the need to account for warming regime, nutrient status, and macrophyte functional composition when predicting climate feedbacks from shallow lakes.

Light quality plays a crucial role in biomass production, biochemical composition, and nutrient removal efficiency in microalgae-based wastewater treatment systems. However, its effects in organic aquaculture wastewater systems remain underexplored. This study investigated the responses of Chlorella sorokiniana CMBB276 to six light qualities (red, blue, white, mixed, red-to-blue, and red-to-mixed) in a system where dissolved organic nitrogen (DON) and phosphorus (DOP) accounted for 83.50 % of total nitrogen and 88.30 % of total phosphorus, respectively. Among the treatments, red light produced the highest biomass (1.54 g L-1), significantly exceeding the biomass achieved under blue light, which yielded the lowest value (0.61 g L-1) on day 16-only 40 % of the yield observed under red light. Additionally, organic matter removal efficiency followed the hierarchy: red light/red-to-mixed/red-to-blue > mixed light > blue light > white light. Across all light treatments, dissolved organic matter (DOM) transformation involved reduced tyrosine-like substances (C1) and increased humic-like substances (C2, C4), with variations in organic matter degradation and growth dynamics. In terms of biochemical composition, protein accumulation was highest under blue light at 30.10 % dry weight (DW), while carbohydrate content peaked under red-inclusive lights, reaching 52.41 % DW under red-to-blue light. These findings demonstrate the potential of C. sorokiniana for nutrient removal and biomass production in aquaculture wastewater, providing insights for optimizing sustainable aquaculture practices.

Macrobenthic fauna are vital to the ecological health of the Yellow River Estuary, yet their long-term population drivers are poorly understood. This study used Boosted Regression Tree models to analyze the spatio-temporal distribution of five dominant species: Glycinde gurjanovae, Sternaspis scutata, Moerella jedoensis, Theora fragilis, and Raphidopus ciliatus. Key environmental drivers included ammonia nitrogen, water depth, sand content of sediment, and water temperature. Specifically, S. scutata and R. ciliatus preferred deeper waters, M. jedoensis favored habitats with moderate sand content of sediment, T. fragilis primarily occurred at water temperatures lower than 25 °C, and G. gurjanovae distribution was most influenced by ammonia nitrogen. All species exhibited a preference for lower ammonia nitrogen concentrations. Inorganic nitrogen and freshwater discharge from the Yellow River significantly influenced the distribution of G. gurjanovae, whereas river discharge alone was positively correlated with areas exhibiting a high occurrence probability (>0.5) for M. jedoensis. Future studies that integrate comprehensive seasonal monitoring data, hydrodynamic conditions, and food availability could further enhance predictive accuracy, providing stronger theoretical and technical support for ecological conservation and management in the Yellow River Estuary.

This study analyzed data from zooplankton surveys conducted in the coastal waters of Rizhao during the summers of 2020-2023 to deterine trends in the number of taxa, dominant taxa, biomass, abundance, and biodiversity over the 4 years. The results indicated the presence of 41 zooplankton species belonging to Hydromedusa, Ctenophora, Copepoda, Cladocera, Amphipoda, Decapoda, Tunicata, Chaetognatha, Chordata, along with 19 types of planktonic larvae. The total number of taxa showed little change over the 4 years. A total of 10 dominant species and 8 dominant larval types were identified in the surveyed waters, and the dominant species vary from year to year. In terms of community structure, planktonic larvae, hydromedusae, and copepods were the dominant taxa. The proportion of planktonic larvae showed an upward trend, while that of hydromedusae exhibited a downward trend. The zooplankton collected by the shallow water type I (SWI) net and shallow water type II (SWII) net in the survey area could each be divided into 2 communities. Correlation analysis revealed that the abundance of zooplankton collected by the (SWI) net was significantly negatively correlated with water temperature (P<0.05), while the Shannon-Wiener index (H ') was significantly positively correlated with water temperature (P<0.05). However, the total number of taxa, abundance, and biomass were significantly higher in the (SWII) net compared to (SWI) net. The average abundance of zooplankton collected in the SWI net gradually decreased over the years(P<0.05). There was no obvious difference in the community diversity indices of zooplankton collected by the two types of nets, and the community structure of zooplankton communities was consistent.

The vertical distribution of phytoplankton plays a crucial role in shaping the dynamics and structure of aquatic communities. In highly dynamic reservoir systems, water level fluctuations significantly affect the physiochemical conditions and the phytoplankton community. However, the specific effects on the vertical characteristics of phytoplankton between the mainstream and the tributary bay of the reservoir remain unstudied. This study investigated the vertical aspects of phytoplankton density, biomass, α and β diversity through monthly sampling over two years in the mainstream (Chang Jiang, CJ) and a tributary bay (Xiang Xi, XX) of the Three Gorges Reservoir in China. Phytoplankton density and biomass were significantly higher in XX, indicating an increased risk of algal blooms in the tributary. The phytoplankton community in CJ showed more stable species-environment relationships, a lower Shannon index and a higher evenness index, suggesting a relatively simple structure and a more uniform distribution of phytoplankton among different water layers. Conversely, XX showed greater differences between water layers (higher β diversity), with significant negative correlations with water level and positive correlations with DO difference, dissolved silica (DSi) difference, and stratification. Peak phytoplankton density and biomass, as well as high β diversity in XX, occurred during periods of decreased water levels with strong stratification in spring and summer. A structural equation model complemented by path analysis revealed that a decrease in water level could increase β diversity either directly through internal processes with extended residence time or indirectly by modifying stratification and the vertical distribution of DSi in XX. Therefore, a proposed water quality management strategy for XX was to increase the water level or reduce β diversity by implementing artificial mixing during stratification periods. Overall, this study lies in its comprehensive investigation of the vertical characteristics of the phytoplankton community in both the mainstream and the tributary bay of the Three Gorges Reservoir, elucidating the significant impact of water level fluctuations and providing insights for targeted water quality management strategies in the tributary bay to mitigate potential ecological impacts.

Reservoirs, heavily influenced by artificial management, often harbor phytoplankton assemblages dominated by cyanobacteria or dinoflagellates, triggering significant changes in aquatic ecosystems. However, due to limited sampling frequency and insufficient attention to species composition, the bloom processes and key characteristics of phytoplankton community structure have not been systematically elucidated. During the low-water level period when blooms are most likely to occur (June to September) in a tributary bay of the Three Gorges Reservoir, daily sampling was conducted to investigate phytoplankton community composition, identify significant environmental factors, and evaluate important structure characteristics of phytoplankton community. The results showed that Microcystis aeruginosa maintained a clear dominance for almost a month in stage 1, with low Shannon and evenness but a high dominance index. Phytoplankton total density and biomass decreased drastically in stage 2, but Microcystis aeruginosa still accounted for some proportion. The highest Shannon and evenness but the lowest dominance index occurred in stage 3. Peridiniopsis niei occurred massively in stage 4, but its dominant advantages lasted only one to two days. NH4-N was responsible for the dominance of Microcystis aeruginosa, while TP and PO4-P was responsible for the dominance of Peridiniopsis niei; however, precipitation contributed to their drastic decrease or disappearance to some extent. The TN : TP ratio could be considered as an important indicator to determine whether Microcystis aeruginosa or Peridiniopsis niei dominated the phytoplankton community. Throughout the study period, physiochemical factors explained more variation in phytoplankton data than meteorological and hydrological factors. Pairwise comparisons revealed an increase in average β diversity with stage progression, with higher β diversities based on abundance data than those based on presence/absence data. Repl had a greater effect on β diversity differences based on presence/absence data, whereas RichDiff had a greater effect on β diversity differences based on species abundance data. Co-occurrence networks for stage 1 showed the most complex structure, followed by stage 4, while the network for stage 3 was relatively sparse, although the overall community division remained compact. This study provides a useful attempt to explore the status and changes in phytoplankton community structure during the bloom process through high-resolution investigation.

A survey of free-living nematodes in Dagu River Estuary of Qingdao was conducted in October 2011, the survey results were analyzed with the help of computer systems and digital intelligence tools. And 113 species or taxonomic entities of free-living nematodes were identified, among which the dominant species were Leptolaimus sp.1, Daptonema sp.1 and Parodontophora sp.1, all of which were non-selective deposit feeders. The abundance, biomass and production of free-living nematodes in the surveyed seas were 2998.6 ind·10cm-2, 1199.4 μg dwt·10cm-2 and 10794.6 μg dwt·10cm-2·a-1, respectively. The average Margalef's richness index (d), Pielou's evenness index (J), Shannon-Weiner diversity index (H′) and Simpson's dominance index (λ) of marine nematodes were 5.56, 0.79, 4.34 and 0.10, respectively. The 8 stations can be divided into 2 groups under a similarity level of 40%.

In the context of carbon peaking and carbon neutrality goals, more and more enterprises realize the importance of green development for enterprise transformation and sustainable development. We explore the impact of big data technology on green logistics performance of manufacturing enterprises by introducing supply chain integration as a mediator variable. We select annual reports of 696 manufacturing company in Shanghai and Shenzhen stock markets, and quantify the level of big data technology using the method of content analysis. The results show that (1) big data technology can positively affect the green logistics performance; (2) supply chain integration can significantly positively affect the green logistics performance; (3) supply chain integration plays a mediation role in the relationship of big data technology and green logistics performance. It confirms the positive impact of big data technology on green logistics performance and enriches relevant research on green logistics performance.

对大神农架地区大型水库库湾-三峡水库香溪河库湾夏季水华期间藻类的营养吸收生长构建了非线性动力学模型.模型反映了时间变化的整体趋势并可模拟藻类生物量峰值.通过改变初始磷浓度,系统均可达到两种藻消亡的平衡态,且模型可在一定程度上预测不同营养水平水体中水华暴发的可能性和强度.展示了动力学系统内部的变化可在一定范围内反映真实世界,通过系统内参数的调节,系统可达到或远离平衡态,以朝生态环境友好的方向发展.

Microcystis and Aphanizomenon are two toxic cyanobacteria genera, which frequently cause blooms in freshwater lakes. In some cases, succession of these two genera was observed in natural water bodies. Among the diverse factors contributing to such succession of dominant cyanobacterial genera, an allelopathic effect was proposed to be involved after the growth inhibitory effect of several Microcystis species on A. flos-aquae was investigated. However, the response of target species exposed to Microcystis are poorly described. In the present study, we used two toxic cyanobacteria strains, Aphanizomenon flos-aquae (Aph1395) and Microcystis aeruginosa strain 905 (Ma905) as research subjects. Aph1395 was inhibited with a necessarily concentrated culture filtrate of Ma905 (MA905-SPE), and the response of the inhibited Aph1395 cells was explored via non-targeted metabolomic profiling. In total, 3735 features were significantly different in the Aph1395 treated with Ma905-SPE vs. those treated with BG11 medium. Among them, the annotations of 146 differential features were considered to be confident via MS/MS spectrum matching analysis. Based on the reported physiological functions of the annotated differential features, we proposed a putative model that in the growth-inhibited Aph1395, a suite of increased or decreased features with activities in apoptosis, growth inhibition, and stress response processes contributed to, or defended against, the allelopathic effect caused by Ma905. Our findings provide insights into the interaction between the bloom forming cyanobacterial species that share the same ecological environment.

基于三峡水库干流和香溪河库湾2003年7月至2013年7月10年间的水质数据,采用Carlson营养状态指数营养状态指数及差值二维坐标评价方法,阐述三峡水库干流和香溪河库湾在蓄水前后10年以来的营养水平,评价其水体营养状态及其限制限制因素,通过建立干支流中营养状态与水动力条件的关系,判断在干支流上水动力条件是否是富营养化的限制因子.结果 表明:蓄水10年来,三峡水库水体营养状态没有出现显著的上升或下降趋势.在三峡水库长江干流水动力条件对营养盐利用几乎没有调控作用.与水库干流不同,在香溪河支流库水动力条件在一定程度上能影响藻类对营养盐的利用,即可通过调节香溪河支流库湾水动力条件来控制藻类水华的发生.

The harvesting of bloom-forming colonial Microcystis flos-aquae using filtration helps with bloom control, the acquisition of a biomass resource and nutrient removal from eutrophic lakes. In this study, two-stage filtration of three combinations for M. flos-aquae harvesting was investigated, and the main factors affecting two-stage filtration performance were analysed. The results showed that compared with filtration with a 5 mu m membrane alone, pre-filtration with a 20 mu m screen improved biomass harvesting rate by 25.03% while 200 mu m and 550 mu m screens pre-filtrations resulted in decreases of 26.90% and 42.20%, respectively. The influences of colony size distribution and cellular concentration on filtration performance were predicted well using a multiple linear regression model (MLR). According to the model analysis, filtrate with larger colony size and narrower size distribution resulted higher harvesting performance. As the cellular concentration increased, the averaged flux decreased, while biomass harvesting rate increased initially, reached the highest value and then decreased. These results could be applied for the development of efficient filtration harvesting strategies for Microcystis bloom control.

Membrane material, pore size, and cleaning strategy are important factors for microalgal membrane harvesting. In this study, harvesting of Scenedesmus acuminatus cultivated in pilot scale using nine ultrafiltration and three microfiltration membranes was carried out in cross-flow filtration system to compare their filtration performance and flux recovery after physical and chemical cleaning. The 0.45-μm PVDF-AsahiKASEI membrane had the highest average flux of 513.6 L m−2 h−1 among 12 membranes and 50-kDa PVC-Litree membrane had the highest average flux of 98.0 L m−2 h−1 among nine ultrafiltration membranes for 60 L S. acuminatus suspension harvesting. There were significantly positive correlations between membrane pore size, pure water flux, and average flux for S. acuminatus suspension harvesting. Generally, ultrafiltration membrane had moderate total fouling index (TFI) and high proportion of hydraulic reversible fouling index (HRFI) of more than 95%. The 0.45-μm PVDF-AsahiKASEI membrane had a low TFI but the lowest proportion of HRFI, associated with the residual microalgal cells, debris, and colloids on the inner surface and top ends of some cells inserted to big membrane pores, demonstrated by SEM image and reduced porosity from 65.9 to 60.2%. Compared to soaking cleaning, circulation cleaning strategy had a better flux recovery efficiency for 0.45-μm PVDF-AsahiKASEI membrane, proving that it would be a potential way in membrane chemical cleaning. This study demonstrated that microfiltration with high flux has great potential in microalgal harvesting if flux recovery efficiency can be significantly increased using suitable cleaning strategy such as circulation cleaning strategy.

In this study, a novel low cost and sustainable microalgal harvesting technique was developed using the concept of coagulant recovery concentration and recycling. Al3+ can be recovered from harvested Scenedesmus acuminatus biomass with 0.1 M HCl, at an acid solution-biomass ratio of 250 ml g(-1). The residual Al3+ content in the purified biomass was reduced to 0.11 +/- 0.0006 mg g(-1), while a higher content of 59.74 +/- 3.11 mgg(-1) was found in the coagulation harvested biomass. The recovered Al3+ solution was concentrated 25 times and then reused for the harvesting of S. acuminatus. The Al3+ recovery and reuse were repeated 5 times, and the harvesting efficiencies were found higher than the fresh Al3+ as a result of the presence of extracellular polymeric substances in the recovered coagulant solution which aided the coagulation process. According to the technical-economic analysis, the cost of chemicals decreased 50% after 5 times recycling.

To unravel fouling and defouling mechanisms of protein, saccharides and natural organic matters (NOM) on polymeric membrane during filtration, this study investigated filtration characteristics on polyvinyl chloride (PVC) ultrafiltration membranes with bovine serum albumin, dextran, humic acid as model foulants. Membrane fouling and defouling performances were analyzed through monitoring the flux decline during filtration and flux recovery during physical backwash. Physico-chemical properties (e.g., hydrophobicity and surface charge) of PVC membrane and foulants were characterized, which were used in the extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory to calculate the interaction energies between membranefoulant and foulant-foulant. The results showed that at the later filtration stages the fouling rate was strongly correlated with the deposition rate, which was determined by the interaction energy profile calculated by EDLVO. Moreover, the adhesion forces of membrane-foulant and foulant-foulant were further measured by atomic force microscopy (AFM) with modified colloidal probes. A positive correlation (R-2 = 0.845) between particle detachment rate (determined by adhesion force) and defouling rate was developed for BSA and HA foulants that led to cake layer formation. By contrast, dextran defouling rate was off this correlation as dextran partially clogged membrane pores due to its smaller size.

Shengjin Lake is an important wintering and stopover habitat for migratory birds en route from East Asia to Australia. The authors investigated the rotifer community structure and environmental factors in upper Shengjin Lake from February to July of 2014. A total of 17 genera and 31 species of rotifers were identified, the dominant species being Brachionus angularis, Brachionus calyciflorus, Asplanchna priodonta, and Schizocerca diversicornis. Rotifer density and the nutrient salt content were higher in the areas inhabited by migratory birds. The highest density (176.0 ind./L) was recorded in June, the lowest (14.0 ind./L) in April. Canonical correspondence analysis (CCA) and correlation analysis showed that some environmental factors, such as temperature, pH, water depth, Secchi depth (SD), and chlorophyll a concentration, had a considerable effect on the lake’s rotifer community structure.

Coagulation with magnesium was found to be more effective for harvesting microalgae Chlorella zofin-giensis with dissolved air flotation (DAF) than the use of Fe3+, Al3+ or chitosan, and the required coagulant dosage was in the order Mg2+ < chitosan < Al3+ < Fe3+. The Mg2+ dosage required depended on the growth phases and culture medium characteristics. An early exponential culture required the highest Mg2+ dosage (226 mg g(-1)), while a late stationary culture required the lowest dosage (36 mg g(-1)). HPO42- and CO32- in the culture medium competed with the microalgal cells for Mg2+ and increased the Mg2+ dosage necessary. No Mg2+ addition was required to harvest the freshwater microalgae Scenedesmus dimorphus grown in a pond with tap water with a high Mg2+ concentration or the marine microalgae Nannochloropsis sp. The critical coagulation pH ranged between 10.8 and 11.8, with a lower pH requirement at a higher Mg2+ concentration. Magnesium hydroxide precipitated with the harvested biomass; however, over 99.5% of the precipitated Mg2+ was recovered by washing the biomass with 0.1 M HCl. Microalgal harvesting with Mg2+ did not introduce extrinsic coagulant; thus, neither the biomass nor the medium was contaminated. (C) 2016 Published by Elsevier Ltd.

This article is part of a special issue with the aim of assessing the potential for Sustainable Development – Policies and Measures (SD-PAM) to stimulate developing country commitments in a future climate regime. In China, agricultural waste products, particularly manure from animal husbandry, represent a local source of rural energy, which can possibly be utilised through simple biogas digesters, thereby promoting rural development. For at least 50 years China has promoted this among farmers’ not only with the goal of providing local clean energy for rural development, but also to improve health and reduce pressure on fuelwood. Until the early 2000s these policies failed or had limited impact, although substantial subsidy-based programmes in the past decade have led to considerable growth. However, our field trip interviews suggest that this growth hides deep-rooted problems. For biogas to fulfil its potential, it is crucial that the policy adapts to the changing realities of Chinese livestock production. Arguably, policies to promote rural biogas combine development goals with mitigation of greenhouse gas emissions in a way that matches well with an SD-PAM mechanism. There are two main ways in which China could benefit from submitting its rural biogas policies to an SD-PAM-based regime. Such a biogas programme could get access to technology and funding for large-scale biogas systems and/or opportunities to sell credits. However, it would need to adapt to the international requirements and to accept international monitoring, reporting and verification (MRV). Alternatively, China could register its rural biogas programme as a unilateral SD-PAM, with less strict MRV requirements. This may win China recognition for its domestic policies, but would then not provide a mechanism for bringing international knowhow or possible financing to China.

The longitudinal patterns of the macroinvertebrate community in the Xiangxi Bay of the Three Gorges Reservoir (TGR) were investigated during the second (2nd) and third (3rd) impoundment stages (October 2006July 2010), to test the effects of increased water level fluctuations (WLF) on the macroinvertebrates. By comparing to the former reports of the first (1st) impoundment stage (inter-annual WLF 4 m), we found that oligochaetes dominated in three different stages in the Xiangxi Bay. However, the total abundance of macroinvertebrates showed a dramatical decline from the 1st to 2nd stage (inter-annual WLF 11 m), but changed slightly from the 2nd to 3rd stage (inter-annual WLF 30 m). This indicated that higher WLF in the 2nd stage had already greatly reduced the macroinvertebrates abundance, thereby the disturbance in the 3rd stage could only slightly affect the already reduced abundance. Three longitudinal zones (the mainstream zone, the lacustrine zone and the transitional zone) were found based on the macroinvertebrate density, biomass, and taxa richness, combined with the geographical location of each site. Significant differences in density and biomass of macroinvertebrate were found among different zones (P < 0.05), yet no significant difference was found in taxa richness (P > 0.05). Two-way indicator species analysis showed that the community type in most sites varied in different seasons from the 2nd stage, exhibiting a dynamic zonation pattern, which differed with the stable pattern of the 1st stage. This seasonal feature was coupled to the seasonal changes of the WLF. ((c) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)