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Microbes play an important role in aquatic carbon cycling but we have a limited understanding of their functional responses to changes in temperature across large geographic areas. Here, we explored how microbial communities utilized different carbon substrates and the underlying ecological mechanisms along a space‐for‐time substitution temperature gradient of future climate change. The gradient included 47 lakes from five major lake regions in China spanning a difference of nearly 15°C in mean annual temperatures (MAT). Our results indicated that lakes from warmer regions generally had lower values of variables related to carbon concentrations and greater carbon utilization than those from colder regions. The greater utilization of carbon substrates under higher temperatures could be attributed to changes in bacterial community composition, with a greater abundance of Cyanobacteria and Actinobacteriota and less Proteobacteria in warmer lake regions. We also found that the core species in microbial networks changed with increasing temperature, from Hydrogenophaga and Rhodobacteraceae, which inhibited the utilization of amino acids and carbohydrates, to the CL500‐29‐marine‐group, which promoted the utilization of all almost carbon substrates. Overall, our findings suggest that temperature can mediate aquatic carbon utilization by changing the interactions between bacteria and individual carbon substrates, and the discovery of core species that affect carbon utilization provides insight into potential carbon sequestration within inland water bodies under future climate warming. [ABSTRACT FROM AUTHOR]

Increasing amount of aluminum (Al) gets into aquatic ecosystem through anthropogenic activity, but the knowledge about Al migration and relationships with sediments possessing different physico-chemical properties in eutrophic lakes is limited. Here, the Al migration rule and relationships with sediment nutritions in the Hangzhou West Lake, China was investigated, where a certain amount of residual Al-salts can enter because of the pre-treatment of the Qiantang River diversion project every day. Results revealed the obvious spatial distribution heterogeneity of Al in sediment vertical direction and horizontal direction following water flow. The Al content in sediment ranged 0.463–1.154 g kg−1 in Maojiabu Lake, and ranged 9.862–40.442 g kg−1 in Xiaonanhu Lake. Higher Al content distributed in upper layer sediment in lake with more disturbance. Total nitrogen (TN) contents were higher 0.917–3.387 mg g−1 and 0.627–0.786 mg g−1 in upper layer sediment than that in lower layer in Maojiabu Lake and Xiaonanhu Lake, respectively. Total phosphorus (TP) content ranged 0.779–2.580 mg g−1, in which IP and Fe/Al-P contributed 24.9–80.8% and 17.0–51.6%, respectively. Correlations between Al content with nutrition, humic acid (HA) etc. of sediment regionally varied in Maojiabu and Xiaonanhu Lake. Spatial distribution of Al-salt in eutrophic lakes closely related with the physico-chemical characteristics of nutrients, humus, human disturbance and water division parameters. Results provides new insight into Al-salts migration and references for Al-risk evaluating in eutrophic lakes. Image 1063 • Increasing amount of Al gets into water bodies due to human activities. • Spatial distribution heterogeneity of Al contents in sediment in eutrophic lake. • Higher Al contents distributed in upper layer sediment for disturbance. • Al contents positive correlated with TN, IP, HA, ORP, negative with OP, pH in sediment. • Conjugation of P-Al, HA-Al may passivate Al-salts entering eutrophic lake. Capsule: Al contents present spatial distribution heterogeneity in sediment in eutrophic lake, and correlate with nitrogen, phosphorus, humic acid content, etc. [ABSTRACT FROM AUTHOR]

We investigated the treatment efficiency of micro-polluted NO3−-dominated river water with low C/N ratio by five parallel pilot-scale IVCWs with different plant and substrate collocation. When the mean concentration was 2.24 and 0.193 mg L−1 in influent, IVCWs achieved an average (mass) removal rate of (0.09 g m−2 day−1) 46.8% and (0.77 g m−2 day−1) 62.3% for TN and TP, respectively, during 1 year of operation. Water quality was significantly improved from grade V to meet the criterion of grade IV of surface water. Through the comparison of removal rate by different IVCWs, we found that lack of carbon sources in influent limited the denitrification in the middle and bottom layers (ML, BL) of IVCW. Zeolites deployed in the upper layer (UL) of IVCW reduced the overall N removal efficiency compared with gravels, due to a stronger nitrification but weaker denitrification. Canna indica (C. indica) was superior to Arundo donax (A. donax) and Thalia dealbata (T. dealbata) for N removal in the UL of IVCW due to higher aboveground biomass accumulation and microbial removal during the first 10 months. Stronger nitrification and denitrification were simultaneously facilitated near the rhizosphere of C. indica. When entered into Dec., A. donax performed higher N removal efficiency than the other two species. The internal replenishment of peats in the ML as carbon sources significantly improved N and P removal efficiency. Zeolites with stronger capacity of ammonium (NH4+) adsorption was more in favor of anammox in the BL, when compared with roseites, but both of them were not conducive to the growth of denitrifiers. However, the deployment of shale ceramisites obtained an opposite result. Gemmata and Pirellula as anammox bacteria were more enriched in the zeolite layer, whereas some anaerobic denitrifiers (Corynebacterium and Paludibacter) and heterotrophic denitrifiers including Bacillus, Geobacter, Pseudomonas, and Lactococcus were more found in shale ceramisite. Supply of peats as carbon sources in the ML was beneficial for the adhesion of anammox bacteria and denitrifiers in the BL of shale ceramisites. An ideal model composed of C. indica + A. donax (DFU)-gravel (UL)-anthracite+peat (ML)-zeolite+shale ceramsite (BL)-Acorus calamus (UFU) was proposed for treating this type of river water to achieve high efficiency. [ABSTRACT FROM AUTHOR]

The aim of the study was to understand the releasing characteristics of sediment phosphorus (P) in all fractions under varying environmental conditions and the relationship between sediment P and eutrophication in shallow city lake, Donghu Lake of Wuhan in China. Effects of P concentration in overlying water, oxygen, light, pH, temperature, and agitation intensity on release processes of sediment P in all fractions in Donghu Lake, China, were investigated. The release quantity and release rate of sediment P in the distilled water were significantly higher than those of lake water, and under anaerobic condition, they were higher than those of aerobic treatment. The concentrations of each P form decreased obviously in both dark and irradiated systems. Both high and low pH promoted the release of Fe/Al-P, IP, and TP, but Ca-P decreased sharply with decreasing pH, while the difference of OP was not obvious. The release rate of each P form accelerated drastically when water temperature rose from 5 to 30°C. The magnitude of the each P form released increased with the increase in the agitation intensity at the first 6 d, while it showed no significant difference after 8 d in different agitation intensities (100–200 rpm). The results showed that the extent of P in all fractions released from Donghu Lake sediment was affected variously by the environmental factors, and the sediment was unstable, at risk of releasing P to Donghu Lake. [ABSTRACT FROM AUTHOR]

A pond-ditch circulation system (PDCS) shows great promises for ecological restoration of rural contaminated water in southern China. In this study, the optimal flow speed, circulation interval, and their combination for the system were investigated for higher pollutant removal efficiency and lower costs in three separate experiments: I, II, and III, respectively. In each experiment, there are three PDCSs (S1, S2, and S3) with different water circulation speeds or circulation intervals, respectively. The results demonstrated that in experiment I, total nitrogen (TN) removal rates, species numbers, and diversity indexes of zooplankton in S1 with a flow speed of 3.6 L/h were significantly higher than those in S2 (7.2 L/h) and S3 (10.2 L/h), respectively. Similarly, in experiment II, S3 circulating every other 4 h had significantly higher TN reduction rates, species numbers, and diversity indexes than S1 and S2 circulating every other 1 and 2 h, respectively. In experiment III, water qualities in S1 (circulation of 3.6 L/h + interval of 4 h) were better than those in S2 (7.2 L/h + 4 h) and S3 (10.2 L/h + 6 h), respectively. Together, circulation at every other 4 h (3.6 L/h) is probably the optimal operating condition for the PDCS in remediating rural contaminated water. [ABSTRACT FROM AUTHOR]

The concentrations of alkylphenols (APs) were investigated in water, sediments and submersed macrophytes from the Moon Lake, Wuhan city, China. The water samples contained APs, ranging up to 26.4μgl−1 for nonylphenol (NP) and 0.68μgl−1 for octylphenol (OP). APs were found in the sediment samples with concentrations ranging from 4.08 to 14.8 for NP and from 0.22 to 1.25μgg−1 dry weight for OP. The samples from the site near former sewage inlet showed the highest concentrations of APs in both water and sediments. The results of distribution pattern and dynamics of NP and OP in submersed macrophytes of the Moon Lake showed that the two pollutants were all found in Myriophyllum verticillatum, Elodea nuttallii, Ceratophyllum oryzetorum, and Potamageton crispus collected from the Moon Lake. For NP, M. verticillatum had the highest capacity of accumulation, followed by E. nuttallii, C. oryzetorum and P. crispus. However the distribution pattern of OP differed from that of NP, and the highest amount of accumulation was observed in E. nuttallii, followed by M. verticillatum, P. crispus, and C. oryzetorum. The temporal pattern of APs was also observed in submersed macrophytes from March to May, and the highest accumulation period was in May. [Copyright &y& Elsevier]

Modified bentonite granulars (MBGs) were prepared by acidification, natrification, calcination, and combined modification methods, and evaluated as effective in-situ adsorption materials to remove sediment phosphorus (P) in all fractions. The morphology and microstructure of MBG were characterized by scanning electron microscope (SEM), X-ray fluorescence (XRF), fourier transform infrared (FTIR) and X-ray diffraction (XRD). Results showed that the P removal capacity of CMBG-Na10-450 treated with 10% (g/g) Na 2 CO 3 and calcined at 450 °C exhibited the highest P removal capacity. Under the optimal conditions of stirring tests, the removal rates of sediment TP, OP, IP, Fe/Al-P and Ca-P by CMBG-Na10-450 were 35.5%, 29.1%, 54.5%, 44.6% and 10.7%, respectively. The adsorption mechanism analysis found that MBG adsorbed sediment P mainly by anionic coordination exchange adsorption. These results indicated that modification enhanced the P adsorption capacity of bentonite, and the MBG can be further applied to control and reduce sediment P in eutrophication remediation. [ABSTRACT FROM AUTHOR]

Submerged macrophyte restoration was used to combat with lake eutrophication and improve water quality in a subtropical, shallow lake. A consistent investigation for three years about macrophyte, phytoplankton, zooplankton and water quality has been conducted to explore the effect of macrophyte restoration on improving aquatic ecosystem. The results showed that macrophyte biomass and coverage after the restoration were as high as 821 g/m 2 and 55%, respectively, and the dominant species were Ceratophyllum demersum , Myriophyllum verticillatum and Potamogeton crispus . Moreover, chemical oxygen demand (COD), total nitrogen (TN), total suspended solids (TSS) and nitrate nitrogen (NN) significantly decreased yearly, but the changes in total phosphorus (TP) and ammonia nitrogen (AN) were not significant during the investigation. Phytoplankton density and biomass significantly decreased, and the dominant species changed from blue-green algae to green algae. Zooplankton density and biomass, however, significantly increased yearly, and the small-sized dominant species (such as, Keratella cochlearis , Polyarthra trigla , etc.) were gradually replaced by the large-sized species (such as, Asplanchna priodonala , Alona guttata , etc.) during the restoration. In addition, macrophyte was negatively correlated with nutrients, but positively correlated with zooplankton. Phytoplankton was also positively related with TN. These correlations showed that restored macrophytes could decrease nutrition loading in water body, inhibit phytoplankton growth to decrease the risk of algae blooms, and support more large-sized zooplankton to strengthen the top-down control of phytoplankton. Therefore, our results showed that macrophyte restoration is a very potential and effective method to combat with the eutrophication and develop water quality in the eutrophic subtropical lakes, and deserves more attentions in future subtropical/tropical lake managements. [ABSTRACT FROM AUTHOR]

To mitigate water pollution caused by rapid urbanization in the rural areas of China, it is urgent to develop suitable wastewater treatment technologies, which are socio-economic, environmentally sustainable and easily maintained. This study investigates the remediation effect of a pond–ditch circulation system on water quality. This system is composed of connected ponds and ditches in rural areas. We constructed the treatment systems as follows: system I (S1) was circulated 24 h/day (13.2 L/h), system II (S2) was static with macrophytes, and system III (S3) was circulated with macrophytes. Our results indicated that after 60 days of treatment, the levels of the total nitrogen, total phosphorus, ammonia nitrogen, chemical oxygen demand, chlorophyll a and turbidity of water significantly decreased in the ponds/ditches of S1 and S3. Similar significant decreases of these parameters were observed in the water of the ditch in S2, whereas the concentrations of TN, TP and NH 4 + -N of water from the two ponds in S2 increased. Moreover, the increase of the species numbers and the diversity index of zooplankton and the decrease of heterotrophic index in three ponds/ditches of S1 and S3 and the ditch of S2 demonstrated the improvement in water quality. The significant relationship between the zooplankton community structure and the environmental variables was confirmed by redundancy analysis (RDA) and Pearson’s correlation analysis. In conclusion, the pond–ditch circulation system can effectively remove excessive nutrient loads and improve water quality and hence represents a simple and economical solution for the restoration of a degraded rural water environment. [ABSTRACT FROM AUTHOR]

Abstract: Constructed wetlands (CWs) have been used in ecological engineering for more than two decades, since 1990. In order to understand the present application and trend of CWs in China, this paper summarized the status quo, prospect and influencing factors in CWs construction, technology application and operation management in China, according to the data obtained by literature survey. Results of the systematic survey showed that CWs technology achieved gradual perfection under pushes of national policies, market demand and technical feasibility, with the capacity of wastewater treatment increasing year by year. However, there were still some problems concerning engineering operation and management. Moreover, the results demonstrated that limited by the economic level, the degree of industrialization and urbanization, climatic conditions as well as land availability, CWs were distributing predominately in the region of 20°13′N–35°20′N in China, where covered the central areas with a subtropical monsoon climate and southern or central areas at province level. In these areas, there were more than 40 plant species, which accounted for 57.14% of the total number of common wetland plants. Most of the CWs composted series or parallel combination forms of the vertical flow and free water surface flow CWs units, and they were suitable to treat more than 20 different types of wastewater. For these CWs, the effluent chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen (TN) and total phosphorous (TP) reached in the ranges of 20–60mg/L, 4–20mg/L, 1–20mg/L and 0.2–1mg/L, respectively. The effluents from CWs were reused in more than eight ways, such as for agricultural irrigation, supplying surface water, green belt sprinkling, etc. [Copyright &y& Elsevier]

• The major species of periphytic algae belong to the Bacillariophyta, Chlorophyta, and Cyanophyta in the West Lake, China. • The species richness of periphytic algae were mainly related to temperature and turbidity. • Diatoms can be used as good indicators species for level of TN in the subtropical urban landscape lakes. Biological indicators of assessing surface waters depend on regionally based indices and sensitivity to environmental conditions. Periphytic algae often used as a potential biological assessment method for its environmental sensitivity characteristics. Here we studied the characteristics of the periphytic algae community and diatom species in the subtropical urban landscape lake known as West Lake, Hangzhou, China, which is in the process of ecological restoration. The changes in species composition, biomass and the community diversity of periphytic algae were determined. 71 taxa of 54 genera of periphytic algae were observed. The Bacillariophyta, Chlorophyta and Cyanophyta dominated in the community. The Bacillariophytes exhibited the highest species richness, whereas the Cyanophytes showed the highest cell density. Principal component analysis environmental variables showed that the TN was main nutrient factor to periphytic algae in the West Lake. In terms of the relatively high TN contents characteristics in subtropical urban landscape lake West Lake, the ecological optimum values and tolerance values of TN about diatom were calculated by weighted regression method. Synedra capitata , Achnanthes minutissima , Gomphonema acuminatum , Navicula graciloides were extracted as indicator species for environmental gradients of TN in the West Lake. Those findings provide a theoretical basis for the use of diatoms biological index to improve the effectiveness of monitoring and evaluating the nutritional level of TN in urban landscape lakes system. It would be significant to identify the nutritional status of the subtropical shallow water bodies and advise related management. [ABSTRACT FROM AUTHOR]

Riverine islands are widespread alluvium wetlands developed in large rivers, and bacterial communities are crucial to their ecological function, yet their assembly processes are rarely addressed. The ecosystem services provided by the middle and the lower Yangtze are primarily threatened by pollution discharge from agricultural land use, and resource overutilization (e.g., embankments), respectively. Here, we assessed bacterial community assembly processes and their drivers within riverine islands in the middle Yangtze River (MR islands) and those in the lower reach (LR islands). A significant distance-decay relationship was observed, although the turnover rate was lower than that of the terrestrial ecosystem with less connectivity. Deterministic and stochastic processes jointly shaped community patterns, and the influence of stochastic increased from 26% in MR islands to 59% for those in LR islands. Meanwhile, the bacterial community in MR islands was controlled more by inorganic nitrogen availability, whereas those in LR islands were governed by pH and EC, although those factors explained a limited fraction of variation in the bacterial community. Potential indicator taxa (affiliated with Nocardioides and Lysobacter ) characterized the waterway transport pollution. Overall, our study demonstrated that bacterial community dissimilarity and the importance of dispersal limitation increased concurrently along the flow direction, while distinct local factors further determined bacterial community compositions by selecting habitat-specificity taxa and particularly metabolism function. These findings enhanced our understanding of the mechanisms driving changes in bacterial communities of riverine islands subject to increased anthropogenic impacts.IMPORTANCERivers are among the most threatened ecosystems globally and face multiple stressors related to human activity. However, linkages between microbial diversity patterns and assembly processes in rivers remain unclear, especially in riverine islands developed in large rivers. Our findings reveal that distinct factors result in divergent bacterial community compositions and functional profiles in the riverine islands in the middle Yangtze and those in the lower Yangtze, with substantial differentiation in deterministic and stochastic processes that jointly contribute to bacterial community assemblages. Additionally, keystone species may play important metabolic roles in coping with human-related disturbances. This study provides an improved understanding of relationships between microbial diversity patterns and ecosystem functions under environmental changes in large river ecosystems., Competing Interests: The authors declare no conflict of interest.

The concentration of heavy metals (HMs) in aquaculture pond sediments significantly affects aquatic food safety and environmental quality. The contamination characteristics, drivers and potential sources of HMs in typical bulk freshwater aquaculture pond sediments in major provinces of China were systematically investigated using a variety of methods and models. Specifically, 130 surface sediment samples were collected from the study area, and the geoaccumulation index (I geo ) and potential ecological risk index (RI) were used to jointly evaluate the characteristics of the HMs. Spearman's correlation and redundancy analysis revealed the main drivers of the HMs. Additionally, the positive matrix factorization (PMF) model and absolute principal component score-multiple linear regression (APCS-MLR) model were used to identify the sources of HMs. The results revealed that the pond sediments were safe for fish culture in most of the study areas. Aquafeed protein content is an important driver of HM concentrations in sediments. The total organic carbon (TOC) content, percentage of clay particles, and pH of the aquaculture pond sediments determined the sediment HMs enrichment abilities as 13.6 %, 52 %, and 9.8 %, respectively. Cd, a significantly enriched pollutant, posed a greater ecological risk than the other five HMs (Cr, Cu, Zn, As, and Pb). Three sources of HMs were identified, including agricultural activity (e.g., aquafeeds, pesticides, and fertilizers), industrial production, and natural sources, with contributions of 44.29 %, 36.66 %, and 19.05 %, respectively. This study provides a scientific basis for minimizing the input and accumulation of HMs in freshwater aquaculture pond sediments, and this can provide insights into the prevention and control of the ecological risks posed by HMs., Competing Interests: Declaration of competing interest The authors declare that they have no competing financial interests or personal relationships that may have influenced the work reported in this study., (Copyright © 2024. Published by Elsevier B.V.)

The restoration of submerged macrophytes is an important step in lake ecosystem restoration, during which artificially assisted measures have been widely used for macrophyte recolonization. Compared with natural restoration, the impact of artificially assisted methods on methane (CH 4 ) production and oxidation of lake sediments remains unclear. Therefore, after the restoration of submerged macrophytes in some parts of West Lake (Hangzhou, China), sediment samples from West Lake were collected according to restoration methods and plant coverage. The CH 4 production potential, oxidation potential, and microbial community structure in the sediment were discussed through whole-lake sample analysis and resampling verification from typical lake areas. From the analysis of the whole lake, the average daily CH 4 production potential (ADP) of artificially restored lake areas (0.12 μg g -1 d -1 ) was significantly lower than that of the naturally restored lake areas (0.52 μg g -1 d -1 ). From the resampling analysis of typical lake areas, the ADP of naturally restored lake areas was 1.8 times that of artificially restored lake areas (P < 0.01). Although there was no significant difference in the CH 4 oxidation potential between the two restoration methods, the presence of submerged macrophytes significantly increased the abundance of the dominant methanotroph Methylocaldum in the sediment, and the rate of increase in the abundance of the dominant methanotroph Methylosinus was significantly higher in artificially assisted restoration than in natural restoration. This study revealed that the artificially assisted restoration of submerged macrophytes reduced the potential for CH 4 production and increased the abundance of dominant methanotrophs in the lake sediment, which would be beneficial for the reduction of CH 4 emissions during lake ecological restoration and environmental management., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

We investigated the long-term effects (6 years) of sediment improvement and submerged plant restoration of a subtropical shallow urban lake, Hangzhou West Lake China. To reveal the lake ecosystems variations, we analyzed the sediment properties, submerged macrophyte characteristics, sediment microorganisms, and benthic macroinvertebrate communities from 2015 to 2020. The ecological restoration project decreased sediment TP and OM, increased submerged macrophyte biomass and sediment microbial diversity, and improved the benthic macroinvertebrate communities in the restored area. The sediment TP decreased from 2.94 mg/g in 2015 to 1.33 mg/g in 2020. The sediment OM of the restored area decreased from 27.44 % in 2015 to 8.08 % in 2020. Principal component analysis (PCA) confirmed that the restoration improved the sediment conditions, making it suitable for the growth of submerged macrophytes, and then sped up the restoration and reconstruction of the lake ecosystem. These results have significant implications on the ecological management of shallow lakes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Restoration of submerged plants in eutrophic lakes can reduce nutrients and phytoplankton biomass in the water body. However, the effect of submerged plants on phytoplankton communities and their photosynthetic activity in situ are still poorly understood. Here, we studied the response of phytoplankton community structure and fluorescence parameters to different submerged plants coverage, the relationship of phytoplankton community and fluorescence parameters with submerged plants coverage and water physicochemical parameters were analysed in sampling area of Hangzhou West Lakes. The results showed that the coverage and biomass of submerged plants were negatively correlated with nitrogen and phosphorus contents in water body but positively correlated with total phenol content. The ratio of nitrogen to phosphorus in the study site changed greatly (32.25-124.54). In spring and summer, Oscillatoria and Leptolyngbya (Cyanophyta) were the dominant species, while in autumn and winter, the dominant species were Cyclotella (Chlorophyta), and Melosira and Cymbella (Bacillariophyta). Compared with Chlorophyta and Bacillariophyta, fluorescence parameters of Cyanophyta were more sensitive to total phosphorus, N:P ratio, total phenols, pH, and electric conductivity. Fluorescence parameters of Chlorophyta and Bacillariophyta were only affected by underwater light. Total phosphorus (TP) and N:P had a negative effect on the maximum photochemical electron yield of Cyanophyta. Furthermore, Cyanophyta was inhibited by total phenols from submerged plants. When phytoplankton were under stress, photochemical electron yield decreased significantly, whereas non-photochemical quenching increased. The structural equation model showed that the coverage of submerged plants might indirectly affect the fluorescence parameters of Cyanophyta by affecting nitrogen, phosphorus, and total phenol contents in the water body. These findings contribute to the understanding of the mechanisms underlying the impact of submerged plant restoration on phytoplankton community dynamics in subtropical eutrophic shallow lakes and provide a theoretical basis for the management of lakes., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The occurrence of ten target pharmaceuticals was investigated in drinking water sources and tap water in a city in the middle reaches of the Yangtze River, including erythromycin (ERY), roxithromycin (RTM), ciprofloxacin (CPX), ofloxacin (OFX), sulfadiazine (SDZ), sulfamethoxazole (SMX), oxytetracycline (OTC), tetracycline (TC), ibuprofen (IBF), and naproxen (NPX). And the corresponding ecological risk for three classes of aquatic organisms and human health risk for different life stages were estimated. Results demonstrated that nine pharmaceuticals except for TC were detected with the frequencies of 20-100% and the concentrations of

In November 2019, an acute disease outbreak in Australian redclaw crayfish (Cherax quadricarinatus) occurred in a farm in Hubei, China, with a cumulative mortality rate of over 80%. One of the characteristic symptoms of the disease was blisters on the tail. This symptom is also common in diseased Procambarus clarkii every year in this country, but the causative agent has not been determined. This study analyzed the etiological characteristics of this disease. Bacterial isolation and identification combined with high-throughput sequencing analysis were conducted to obtain the microbiota characteristics in the hemolymph, hepatopancreas, and intestines. Results showed that this outbreak was caused by infection from Aeromonas hydrophila and Aeromonas veronii. The underlying cause was stress imposed on crayfish during transferring from outdoor pond to indoor pond because of temperature drops. Aeromonas infection caused remarkable changes in the structure of the microbial composition in the hemolymph, hepatopancreas, and intestines of the crayfish. The abundance of Aeromonas in the hemolymph of the sick crayfish was as high as 99.33%. In particular, KEGG metabolic pathway analysis showed that some antibiotic synthesis, enterobactin biosynthesis, and myo-inositol degradation pathways were abundant in healthy crayfish hemolymphs, which may be the mechanism of maintaining crayfish health. Conversely, inhibition of these pathways led to the disorder of microbiota structure, finally leading to the occurrence of diseases. To the knowledge of the authors, this study was the first to use high-throughput amplicon sequencing targeting the 16S rRNA gene to find the causative bacteria in aquatic animals. This protocol can provide more comprehensive and reliable evidence for pathogen identification, even if the pathogenic bacteria are anaerobes or other hard-to-culture bacteria., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The community composition and biomass of phytoplankton in shallow lakes are impacted by many environmental factors including water quality physicochemical parameters, land use in the watershed, and lake morphology. However, few studies have simultaneously evaluated the relative importance of these factors on the effect of community composition and biomass of phytoplankton. The relative importance of the water quality physicochemical parameters (water temperature [WT], total nitrogen [TN], total phosphorus [TP], pH, dissolved oxygen [DO], electrical conductivity [EC], turbidity and Secchi depth [SD]), land use (built-up land, farmland, waters, forest, grassland, and unused land) in the watershed, and lake morphology (area and depth) on the composition and biomass of phytoplankton communities were assessed in 29 subtropical shallow lakes in Wuhan, China, during different seasons from December 2017 to November 2018. The results showed that phytoplankton in all 29 lakes was mainly composed of Cyanophyta, Chlorophyta, and Bacillariophyta. Phytoplankton abundance was highest in summer and lowest in winter. We analyzed the relative importance of the three groups of variables to the community composition of the phytoplankton by variance decomposition. The results showed that the three groups of environmental variables had the highest explanation rate (> 80%) for the composition of the phytoplankton community in summer and autumn, and the explanation rates in spring and winter were 42.1% and 39.8%, respectively. The water quality physicochemical parameters were the most important variables affecting the composition of phytoplankton communities, followed by land use in the watershed. Through generalized additive model and structural equation model analysis, we found that the land use and lake morphology had minimal direct impact on the Chl-a and cell density of phytoplankton, mainly by altering the TN, TP, turbidity, SD, DO, and EC, which indirectly affected phytoplankton. WT and nutrients were still the main predictors of phytoplankton abundance. Built-up land was the main source of nitrogen and phosphorus in lakes. Correlation analysis found that forest and grassland had positive impacts on reducing lake nitrogen and phosphorus contents. This showed that increasing grassland and forest in the watershed could reduce the pollutants entering the lake. Our findings will contribute to water quality management and pollution control for subtropical shallow lakes., (Copyright © 2021. Published by Elsevier Ltd.)

During decay, the sediment microenvironment and water quality are severely affected by excessive proliferation of harmful algae such as filamentous green algae (FGA). The frequency of this FGA is increased through global warming and water eutrophication. In the present study, the degradation processes of a common advantage FGA Cladophora oligoclora and its effect on nitrogen and phosphorus nutrient structure and bacterial community composition at the sediment-water interface were investigated by stable isotope labelling and high-throughput sequencing. The results showed that the decomposition process of C. oligoclona was fast, stable, and difficult to degrade. The changes in sediment δ 15 N values reached 66.68 ‰ on day 40, which indicated that some of the nitrogen had migrated to the sediment from C. oligoclona litter. TN and NH 4 + -N in the overlying water rapidly increased between days 0-10, NH 4 + -N rose to 78.21% of TN on day 40, resulting in severe pollution of ammonia in the overlying water. The nitrogen forms and contents in the sediment are mainly derived from the increasing ammonia nitrogen release. The TP and IP in the overlying water increased to the highest concentrations of 6.68±0.64, 6.59±0.79 mg·L -1 during the decomposition process, respectively, resulting in the migration of phosphate to the sediments with increasing phosphorus content. The abundance of the main dominant bacterial communities, such as Acinetobacter (0.08%-62.48%) and Pseudomonas (0.13%-20.36%) in sediments and overlying water has changed significantly. The correlation analysis results suggested that the phosphorus was mainly related to the bacterial community in the overlying water, while the various forms of nitrogen demonstrated a high relevance with the bacterial community in the sediment. Our research results will be valuable in evaluating the potential ecological risk of FGA decomposition and provide scientific support for shallow lake management and submerged vegetation restoration., Competing Interests: Declaration of Competing Interest The authors declared no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Submerged macrophyte restoration is the key stage in the reestablishment of an aquatic ecosystem. Previous studies have paid considerable attention to the effect of multiple environmental factors on submerged macrophytes. Meanwhile, few studies have been conducted regarding the spatial and seasonal characteristics of water and sediment properties and their long-term relationship with submerged macrophytes after the implementation of the submerged macrophytes restoration project. On a monthly basis, we monitored the spatial and seasonal variation in water parameters, sediment properties, and the submerged macrophyte characteristics of West Lake in Hangzhou from August 2013 to July 2019. From these measurements, we characterized the relationship between environmental factors and submerged macrophytes. Water nutrient concentrations continuously decreased with time, and the accumulation of sediment nutrients was accelerated as the submerged macrophyte communities developed on a long-term scale. The results indicated that the difference in water parameters was due to seasonal changes and land-use types in the watershed. The differences in the sediment properties were mainly attributed to seasonal changes and changes in the flow field. Redundancy analysis showed that the influence of water nutrients on the submerged macrophyte distribution was greater than that of sediment nutrients. The result also suggested that the developed root system, high stoichiometric homeostasis coefficients of P, and compensation ability of substantial leaf tissue may lead to a large distribution of Vallisneria natans in West Lake in Hangzhou. The correlation of water parameters and sediment properties with submerged macrophytes for a long time was very important as the restoration was achieved. To ensure the stability of the aquatic ecosystem after performing the submerged macrophyte restoration, a greater emphasis must be placed on reestablishing the entire ecosystem, including the restoration of aquatic animals and fish stocks. We expect these findings to serve as a reference for researchers and government agencies in the field of aquatic ecosystem restoration., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Biomanipulation of filter-feeding bivalves or fish can serve as complementary measures to zooplankton manipulation approach in lakes dominated by large-sized algae. A laboratory grazing experiment was conducted to compare the selective grazing of benthic bivalves (Hyriopsis cumingii) and planktivorous fish (silver carp) on particle size and algae species. Their combination grazing effects were also detected. The results showed that the clearance rates of silver carp were higher than that of H. cumingii, and that silver carp preferred particles in the 30-50 and 50-100 μm size fraction whereas H. cumingii did not show a significant selective grazing on seston size. Furthermore, the differences between the selective grazing of H. cumingii and silver carp on algae species were detected. Some algae species, which had not been digested well by silver carp, were not detected in H. cumingii's pseudofeces. Similarly, some algal species in the pseudofeces of bivalves were not detected in the feces of fish. Moreover, the combined clearance rates of H. cumingii and silver carp (ranging from 12.14 to 95.99 mL g DW -1  h -1 ) were higher than that of single filter feeder (0.47 to 10.18 mL g DW -1  h -1 ). We suggest therefore that when using biomanipulation measures to control large-sized algal overgrowth, a combination of different filter feeders may be a better way considering their collaborative grazing in both particle size and algae species selectivity.

Introduction: Escherichia coli is a commensal bacterium in humans, animals, and the environment that is one of the microorganisms commonly resistant to antimicrobials. Cooked meat products, which are popular in China, are easily contaminated by E. coli during processing and storage., Methodology: In this study, a total of 75 E. coli isolates from cooked meat products in Henan province, China, were assayed for the presence of and horizontal transfer of class 1 integrons., Results: Class 1 integrons were detected in 11 (14.7%) of these isolates, and contained four groups of resistance gene cassettes, including dfrA17-aadA5, dfrA1-aadA1, dfrA12-orfF-aadA2, and an uncommon array of aacA4-catB8-aadA1. The transfer frequency of selected integron-positve donors ranged from 10(-6) to 10(-4) transconjugants per recipient cell, and the integron-containing DNA from the donors could be transferred to E. coli J53Azr with the transformation frequency of 10(-7) to 10(-5)., Conclusions: Class 1 integrons could be transferred to recipient E. coli J53 by conjugation and natural transformation. These findings suggest the role of commensal E. coli isolates from cooked meats as an important reservoir for integrons and the possible transfer of antimicrobial resistance genes to humans via the food chain.

Introduction: Salmonellosis remains one of the most frequently occurring foodborne diseases worldwide, especially in developing countries. The increasing prevalence of multidrug resistance among Salmonella isolates from food has been an emerging problem in China., Methodology: In this study, a total of 638 food samples including raw meat, seafood, vegetables, and cooked meat were collected in Henan province of China between July 2007 and August 2008 to determine the prevalence of Salmonella. These isolates were subjected to serotyping, antimicrobial susceptibility, presence of class 1 integrons, and horizontal transfer of integrons., Results: The overall percentage of Salmonella prevalence was 9.7% (n = 62). Among these isolates, S. Anatum and S. Senftenberg were most common, and high rates of antimicrobial resistance were observed to sulfamethoxazole (90.3%), trimethoprim/sulfamethoxazole (87.1%), streptomycin (29.0%), and ciprofloxacin (25.8%). Class 1 integrons were detected in 16.1% of these isolates, and contained gene cassettes dfrA12-aadA2, dfrA1-aadA1, and dfrA1. Three Salmonella isolates could transfer their integrons and resistance genes to Escherichia coli by conjugation., Conclusions: Our findings indicate that the mobile DNA elements could play an important role in the dissemination of resistance determinants among those Salmonella isolates.

To examine the performance of a constructed wetland system on stormwater runoff and domestic sewage (SRS) treatment in central east China, two parallel pilot-scale integrated constructed wetland (ICW) systems were operated for one year. Each ICW consisted of a down-flow bed, an up-flow bed and a horizontal subsurface flow bed. The average removal rates of chemical oxygen demand (CODCr), total suspended solids (TSS), ammonia (NH4(+)-N), total nitrogen (TN) and total phosphorus (TP) were 63.6, 91.9, 38.7, 43.0 and 70.0%, respectively, and the corresponding amounts of pollutant retention were approximately 368.3, 284.9, 23.2, 44.6 and 5.9 g m(-2) yr(-1), respectively. High hydraulic loading rate (HLR) of 200 mm/d and low water temperatures (<15 °C) resulted in significant decrease in removals for TP and NH4(+)-N, but had no significant effects on removals of COD and TSS. These results indicated that the operation of this ICW at higher HLR (200 mm/d) might be effective and feasible for TSS and COD removal, but for acceptable removal efficiencies of nitrogen and phosphorus it should be operated at lower HLR (100 mm/d). This kind of ICW could be employed as an effective technique for SRS treatment.