Search

• The diversity and composition of algal community exhibited temporal pattern. • Network elucidated the complex interactions among algae in different lakes. • Keystone algal-species played an integral role in maintaining ecological stable. • Structural equation model was built between water quality and algal community. • The responses of algal communities to water quality parameters were distinct. Urban lakes were critical in aquatic ecology environments, but how environmental factors affected the distribution and change characteristics of algal communities in urban lakes of Xi'an city was not clearly. Here, we investigated the algal community structure of six urban lakes in Xi'an and evaluated the effects of water quality parameters on algae. The results indicated that the significant differences on physicochemical parameters existed in different urban lakes. The maximum concentration of total phosphorus in urban lakes was (0.18 ± 0.01) mg/L and there was a phenomenon of phosphorus limitation. In addition, 51 genera of algae were identified and Chlorella sp. was the dominant algal species, which was affiliated with Chlorophyta. Network analysis elucidated that each lake had a unique algal community network and the positive correlation was dominant in the interaction between algae species, illustrating that mature microbial communities existed or occupied similar niches. Redundancy analysis illustrated that environmental factors explained 47.35% variance of algal species-water quality correlation collectively, indicating that water quality conditions had a significant influence on the temporal variations of algae. Structural equation model further verified that algal community structure was directly or indirectly regulated by different water quality conditions. Our study shows that temporal patterns of algal communities can reveal the dynamics and interactions of different urban ecosystem types, providing a theoretical basis for assessing eutrophication levels and for water quality management. [Display omitted]. [ABSTRACT FROM AUTHOR]

• PAEs in water from the Three Gorges Reservoir area were investigated. • PAEs polluted the upper reaches of the Yangtze River more than the middle reaches. • Molecular weight and log K ow significantly affected the input and losses of PAEs. • DnNP may cause potential adverse effects for the aquatic ecology. Phthalic acid esters (PAEs) are a group of compounds widespread in the environment. To investigate the occurrence and accumulation characteristics of PAEs, surface water samples were collected from the Three Gorges Reservoir area, China. The total concentrations of 11 analyzed PAEs (∑ 11 PAEs) in the collected water samples ranging from 197.7 to 1,409.3 ng/L (mean ± IQR: 583.1 ± 308.4 ng/L). While DEHP was the most frequently detected PAE, DnBP and DnNP were the most predominant PAEs in the analyzed water samples with a mean contribution of 63.3% of the ∑ 11 PAEs. The concentrations of the ∑ 11 PAEs in the water samples from the upper reaches of the Yangtze River were significantly higher than those from the middle reaches. To better understand the transport and fate of the PAEs, seven detected PAEs were modeled by Quantitative Water Air Sediment Interaction (QWASI). The simulated and measured values were close for most PAEs, and differences are within one order of magnitude even for the worst one. For all simulated PAEs, water and particle inflow were main sources in the reservoir, whereas water outflow and degradation in water were important removal pathways. The contribution ratios of different sources/losses varied from PAEs, depending on their properties. The calculated risk quotients of DnNP in the Three Gorges Reservoir area whether based on monitoring or simulating results were all far exceeded the safety threshold value, implying the occurrence of this PAE compound may cause potential adverse effects for the aquatic ecology of the Three Gorges Reservoir area. [Display omitted] [ABSTRACT FROM AUTHOR]

• A gas permeable membrane electrode assembly was developed. • It integrated anode and cathode on each side of gas permeable membrane, respectively. • It was assembled in a stacked transmembrane electro-chemisorption system. • It enhanced ammonia recovery from wastewater via in situ utilization of authigenic acid and base. • It showed features of excellent performance, energy saving and easy scale-up. Ammonia recovery from wastewater is of great significance for aquatic ecology safety, human health and carbon emissions reduction. Electrochemical methods have gained increasing attention since the authigenic base and acid of electrochemical systems can be used as stripper and absorbent for transmembrane chemisorption of ammonia, respectively. However, the separation of electrodes and gas permeable membrane (GPM) significantly restricts the ammonia transfer-transformation process and the authigenic acid-base utilization. To break the restrictions, this study developed a gas permeable membrane electrode assembly (GPMEA), which innovatively integrated anode and cathode on each side of GPM through easy phase inversion of polyvinylidene fluoride binder, respectively. With the GPMEA assembled in a stacked transmembrane electro-chemisorption (sTMECS) system, in situ utilization of authigenic acid and base for transmembrane electro-chemisorption of ammonia was achieved to enhance the ammonia recovery from wastewater. At current density of 60 A/m2, the transmembrane ammonia flux of the GPMEA was 693.0 ± 15.0 g N/(m2·d), which was 86 % and 28 % higher than those of separate GPM and membrane cathode, respectively. The specific energy consumption of the GPMEA was 9.7∼16.1 kWh/kg N, which were about 50 % and 25 % lower than that of separate GPM and membrane cathode, respectively. Moreover, the application of GPMEA in the ammonia recovery from wastewater is easy to scale up in the sTMECS system. Accordingly, with the features of excellent performance, energy saving and easy scale-up, the GPMEA showed good prospects in electrochemical ammonia recovery from wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

• First survey on wild adult black flies in Malaysia using malaise trap. • 14.7 % of black flies species in Malaysia were caught including a few unknown species. • Adult female of Simulium tanahrataense was discovered for the first time. • Adult S. pahangense was caught for first time after 20 years. Most studies on black flies focus on the taxonomy and ecology of their aquatic stages. Despite posing a public health threat, the adults remain poorly studied in many countries, including Malaysia. The present study represents the first investigation of the distribution of wild-caught black flies from various ecological landscapes and climatic conditions in Malaysia. CO 2 -baited Malaise traps were set randomly at 41 sampling sites across Peninsular Malaysia from 2020 to 2023. In total, 532 black flies belonging to 14 species of four subgenera were captured. To ensure taxonomic rigor, specimens were identified to species morphologically and molecularly. The subgenus Gomphostilbia was the most abundant (71.43 %), followed by Simulium (14.28 %) and Davieselleum and Nevermannia each representing 7.14 % of the total captures. These species represented 14.74 % of the total species recorded from Malaysia. The most frequently collected species were Simulium roslihashimi (24.39 %), followed by S. aureohirtum, S. vanluni , and S. (Gomphostilbia) sp. 1 with 7.32 % each. The highest relative abundance was found for S. vanluni (86.09 %) and S. roslihashimi (7.14 %). Most species were found at elevation below 300 m (78.57 %); fewer were at elevation higher than 1,000 m (21.43 %). Two principal components accounted for 85.3 % of the total intersite variance. Simulium roslihashimi was found at almost every site, with a maximum relative humidity of 90 %. Simulium aureohirtum and S. vanluni were found at sites with relative humidity up to 73 %, but S. aureohirtum was found at higher temperatures (31 °C) compared with S. roslihashimi (28 °C) and S. vanluni (29 °C). The present study establishes the groundwork for further studies of wild adults in Malaysia and identifies the need to use more traps over the range of seasons and environmental conditions, particularly near breeding sites. [ABSTRACT FROM AUTHOR]

Disturbance regimes related to water level fluctuation play an important role in the structuring of aquatic macrophyte communities. In managed systems, winter water level drawdowns have shown promise in controlling populations of nuisance macrophytes, however, drawdowns may have unintended negative consequences on erosion, fauna, and non-target plant species. The Chippewa Flowage, located in Sawyer County, WI, has implemented targeted winter water level drawdowns with the goal of reducing nuisance levels of Myriophyllum spicatum. To evaluate the effects of water level drawdowns on Myriophyllum spicatum and the native macrophyte community, we conducted repeated full lake surveys of aquatic macrophytes at 2018 points under drawdown and normal water level management in 2005/06, 2015, and 2017. We supplemented these efforts with downscaled surveys in 2007, 2010, and 2016. Surveys revealed a statistically significant decline in both Myriophyllum spicatum occurrence and abundance, and average macrophyte abundance during active drawdown management. Kernel distributions of change in point-specific c-value between the two time periods showed a significant increase under drawdown conditions, and a decrease under normal management (D = 0.41, P ≤0.0001). Drawdown management appeared to successfully control Myriophyllum spicatum abundance and allowed for improvements in the floristic quality of the macrophyte community but resulted in reduced macrophyte abundance overall. [ABSTRACT FROM AUTHOR]

Hypersaline environments are extreme habitats with a limited prokaryotic diversity, mainly restricted to halophilic or halotolerant archaeal and bacterial taxa adapted to highly saline conditions. This study attempts to analyze the taxonomic and functional diversity of the prokaryotes that inhabit a solar saltern located at the Atlantic Coast, in Isla Cristina (Huelva, Southwest Spain), and the influence of salinity on the diversity and metabolic potential of these prokaryotic communities, as well as the interactions and cooperation among the individuals within that community. Brine samples were obtained from different saltern ponds, with a salinity range between 19.5 % and 39 % (w/v). Total prokaryotic DNA was sequenced using the Illumina shotgun metagenomic strategy and the raw sequence data were analyzed using supercomputing services following the MetaWRAP and SqueezeMeta protocols. The most abundant phyla at moderate salinities (19.5–22 % [w/v]) were Methanobacteriota (formerly "Euryarchaeota"), Pseudomonadota and Bacteroidota , followed by Balneolota and Actinomycetota and Uroviricota in smaller proportions, while at high salinities (36–39 % [w/v]) the most abundant phylum was Methanobacteriota, followed by Bacteroidota. The most abundant genera at intermediate salinities were Halorubrum and the bacterial genus Spiribacter , while the haloarchaeal genera Halorubrum , Halonotius , and Haloquadratum were the main representatives at high salinities. A total of 65 MAGs were reconstructed from the metagenomic datasets and different functions and pathways were identified in them, allowing to find key taxa in the prokaryotic community able to synthesize and supply essential compounds, such as biotin, and precursors of other bioactive molecules, like β-carotene, and bacterioruberin, to other dwellers in this habitat, lacking the required enzymatic machinery to produce them. This work shed light on the ecology of aquatic hypersaline environments, such as the Atlantic Coast salterns, and on the dynamics and factors affecting the microbial populations under such extreme conditions. [Display omitted] • Taxonomic diversity of the prokaryotic community of the saltern decreases with the salinity increase. • Functional metabolic diversity is not significantly correlated with the salt concentration range. • Key taxa produce biomolecules that other community members use for metabolism or to synthesize essential compounds. • Reconstructed bins are found in hypersaline environments worldwide, showing their euryhaline character and wide dispersion. [ABSTRACT FROM AUTHOR]

The importance of earthworms for soil functioning is widely accepted and is mainly linked to their burrowing, feeding and casting behaviours. However, our knowledge of earthworm behavior is still limited by the lack of efficient and easy-to-use methods. In this work, we describe and test a new marker of earthworm bioturbation. Dense particles of tungsten, visible in X-ray images, were located at a certain depth in repacked soil cores inoculated by either Lumbricus terrestris or Aporrectodea caliginosa , alone or in combination. This marker was compared to the classical luminophore method (i.e. colored sand particles) generally used in aquatic ecology. The dynamics of both the burrow systems and the casting activities was followed using X-ray tomography every two weeks for a period of 10 weeks. Below ground casting activities could be assessed since parts of the casts excreted by the earthworms were marked by tungsten and appeared white in the images. The time dynamics of both burrow and cast productions were almost linear and significantly influenced by the earthworm species and the presence of litter. As expected, L. terrestris created larger (up to 50 cm3) and deeper burrow systems and made fewer macropores compared to A. caliginosa. Surprisingly, both species were equally influenced by the presence of litter, and this highlighted their behavioral plasticity. For example, A. caliginosa decreased by 32 % the volume of burrows in the presence of litter and the resulting burrow system was significantly shallower which showed that this endogeic species is indeed able to partly feed on surface litter. The use of tungsten particles is a promising new tool to accurately characterize the casting activities of earthworms in the soil and to study behavioral plasticity under the influence of environmental factors. • Tungsten (W) particles were tested s a new bioturbation marker visible in X-ray. • When W mixed with soil is egested by earthworms, casts appeared white in X-ray images. • W had no short-term toxicity for Lumbricus terrestris or Aporrectodea caliginosa. • Litter presence at the soil surface influences bioturbation dynamics for both species. [ABSTRACT FROM AUTHOR]

• Reservoir oxygen supply mode is regulated by thermodynamics and hydrodynamics. • Longitudinal oxygen supplies greatly impact hypoxia evolutions in reservoirs. • The regulation of outflow elevation in cascade reservoirs can alleviate hypoxia. • Runoff increase under climate change could ease the current worsening hypoxia. Hypoxia in stratified waters greatly threatens aquatic ecology and societal development owing to enhanced nutrient discharge and increasing global temperature. Current research predominantly alleviates hypoxia by reducing dissolved oxygen (DO) consumption or conducting hypolimnetic oxygenation, yet their implementation has encountered bottlenecks. Therefore, this study explores the potential of increasing the inherent DO supplies in stratified reservoirs to mitigate hypoxia. High-frequency in situ observations and massive modeling experiments are integrated to discern the DO supply mode and the dominant driver of DO evolution. Results indicate that periodic thermodynamic conditions determine the DO supply relationships between oxygen sources (inflow carriage, reaeration, and photosynthesis) for different water layers. Thermal stratification causes the hypolimnion to rely mostly on the inflow for DO supply, leading to a fragile budget prone to hypoxia. However, episodic hydrodynamic events (turnover, wind stir, density current, and flood) can promote DO supply and inhibit hypoxia. Temperature and DO regimes are primarily driven by outflow conditions, followed by inflow and meteorology conditions. Furthermore, hypolimnetic hypoxia can be regulated by altering inflow volume, outflow volume, and outlet elevation. These findings highlight the importance of longitudinal solute exchange in DO evolution in stratified reservoirs, providing a basis for alleviating hypoxia through cascade reservoir operations. [Display omitted] [ABSTRACT FROM AUTHOR]

Aquatic Embryophytes play a key role in the proper functioning of aquatic ecosystems, where carbon (inorganic and organic forms) is pivotal in biogeochemical processes. There is growing awareness that mixotrophy, the direct use of exogenous organic carbon by autotrophs, is a widespread phenomenon and that it has emerged recurrently in the evolution of many autotrophic lineages. Despite living in an environment providing organic matter and presenting many favourable predispositions, aquatic plants from the Embryophytes, except carnivorous ones, have never been deeply investigated for mixotrophy. Here, we address the possibility that aquatic plants may exhibit mixotrophy, a prospect overlooked by research until now, and that this may be much more widespread than imagined under the conventional paradigm of plants considered as strict autotrophs. Aquatic plants are crucial for the proper functioning of aquatic environments. So far, mixotrophy, widespread in aquatic microbial communities and in certain terrestrial plants, has been studied rarely in aquatic plants other than carnivorous ones. New evidence, particularly in Lemna and other close genera, suggests that mixotrophy is much more widespread than previously thought. Three processes could be involved, namely biotrophic associations, capture of prey (e.g., in carnivorous plants), and absorbotrophy (uptake of dissolved organic carbon). The latter process seems to be the most probable hypothesis in regard to the physiology of aquatic plants, but further research at both organism and cellular levels is needed to understand and clarify the processes involved and their importance. This opinion opens a new window of opportunity in aquatic ecology, with possible unsuspected applications in water management. [ABSTRACT FROM AUTHOR]

The larval stage of invasive Dreissena spp. mussels (i.e., veligers) are understudied despite their seasonal numerical dominance among plankton. We report the spring and summer veliger densities and size structure across the main basin, North Channel, and Georgian Bay of Lake Huron, and seek to explain spatiotemporal variation. Monthly sampling was conducted at 9 transects and up to 3 sites per transect from spring through summer 2017. Veliger densities peaked in June and July, and we found comparable densities and biomasses of veligers between basins, despite differences in density of juvenile and adult mussels across these regions. Using a generalized additive model to explain variations in veliger density, we found that temperature, chlorophyll a , and nitrates/nitrites were most important. We generated an index of veliger attrition based on size distributions that revealed a higher rate of attrition in the North Channel than the rest of the lake. A logistic model indicated a threshold calcium concentration of around 22 mg/L was necessary for veligers to survive to larger sizes and recruit to their juvenile and benthic adult life stages. Improved understanding of factors that regulate the production and survival of Dreissena veligers could improve the ability of managers to assess future invasion threats as well as explore potential control options. [ABSTRACT FROM AUTHOR]

Diffuse pollution, including that in the lower and middle reaches of the Yangtze River, is the primary source of pollution in several agricultural watersheds globally. As the largest river basin in China, the Yangtze River Basin has suffered from total phosphorus (TP) pollution in the past decade owing to diffuse pollution and aquatic ecology destruction, especially in the midstream tributaries and mid-lower reaches of the lakes. However, the transport dynamics of diffuse pollutants, such as phosphorus (P) from land to water bodies have not been well evaluated, which is of great significance for quantifying nutrient loss and its impact on water bodies. In this study, diffuse pollution estimation with remote sensing (DPeRS) model coupled with Soil and Water Assessment Tools (SWAT) was utilized to simulate the transport dynamics of P, investigate the spatial heterogeneity and P sources in the Poyang Lake Basin. Additionally, the P transport mechanism from land to water and the migration process in water bodies were considered to investigate the impact of each loss unit on the water body and evaluate the load generated by diverse pollution types. The estimated diffuse TP loss was 6016 t P·yr−1, and the load to inflow rivers and to Poyang Lake were 11,619 and 9812 t P·yr−1, respectively. Gan River Basin (51.09%) contributed most TP to Poyang Lake among five inflow rivers, while waterfront area demonstrated the highest TP load per unit area with 0.057 t km−2·yr−1. Our study also identified P sources in the sub-basins and emphasized agricultural diffuse sources, especially planting, as the most significant factor contributing to TP pollution. Additionally, to improve the aquatic environment and water ecological conditions, further nutrient management should be applied using a comprehensive approach that encompasses the entire process, from source transportation to the water body. [Display omitted] • A watershed model apportioned phosphorus loads from sources to entire lake basin. • Critical phosphorus loss zone throughout basin were identified. • Diffuse TP pollution, especially from the planting, contribute most loads to the studied lake. • The TP load into lake decreased compared to the load to rivers. [ABSTRACT FROM AUTHOR]

Imaging spectrometers provide important Earth surface data for terrestrial and aquatic ecology, hydrology, geology through retrieved surface reflectance spectra. Surface reflectance is generally recovered from measured radiance through model inversions of the surface and atmospheric system. Most retrieval approaches treat all pixels independently and ignore spatial correlations in the atmosphere for neighboring pixels, resulting in surface-related biases in the retrieved surface and atmospheric parameters. In this work, we present a mathematical framework to more accurately retrieve surface reflectance and atmospheric parameters by leveraging the expected spatial smoothness of the atmosphere. This framework retrieves the full spatial–spectral reflectance data cube in a computationally efficient manner and is to our knowledge the first approach capable of accurately finding this global solution for large imaging spectroscopy datasets. We implement this mathematical framework in an example proposed algorithm which we call spatially constrained optimal estimation (SCOE). We show that SCOE improves the overall surface reflectance retrieval error, reduces surface-related biases in the retrieved surface reflectance and atmospheric parameters, and is more robust to noise than a traditional pixel-by-pixel approach and an operational empirical line approach in simulated and experimental results. This reduction in surface reflectance error will impact science data products across application areas, making imaging spectroscopy algorithms more robust for global acquisitions. • Global VSWIR imaging spectroscopy requires robust surface and atmospheric retrievals. • We present a novel joint spatial and spectral surface reflectance retrieval algorithm. • This algorithm leverages atmospheric spatial smoothness for improved retrievals. • Improved reflectance spectra will lead to better global imaging spectroscopy products. [ABSTRACT FROM AUTHOR]

• Diatoms play vital role in the aquatic ecology as primary producers. • Biorefinery approach towards enhanced production of high value products are needed. • Diatomaceous earth is a highly valuable product generated after the death of diatoms. • Diatoms are significant in aquaculture converting waste to wealth. Diatoms, with their complex cellular architecture, have been recognized as a source of limitless potential. These microbes are common in freshwater and marine habitats and are essential for primary production and carbon sequestration. They are excellent at utilizing nutrients, providing a sustainable method of treating wastewater while also producing biomass rich in beneficial substances like vitamins, carotenoids, polysaccharides, lipids, omega-3 fatty acids, pigments, and novel bioactive molecules. Additionally, they are highly efficient organisms that can be employed to monitor the environment by acting as trustworthy indicators of water quality. This comprehensive review explores the multifaceted applications of diatoms in a variety of fields, such as bioremediation, aquaculture, value-added products, and other applications. The review set out on a path towards greener, more sustainable methods amicable to both industry and the environment by utilizing theenormous diverse biotechnological potentials of diatoms. [ABSTRACT FROM AUTHOR]

Water pollution has become a serious problem in aquatic ecology due to the oil spills and the consistent release of industrial pollutants, such as dyes. Herein, we report a simple method to fabricate superwetting caffeic acid (CA)-polyethyleneimine (PEI)-modified melamine sponges (CA-PEI-MS) for oil-in-water emulsion separation and dye adsorption. The as-fabricated CA-PEI-MS exhibited superhydrophilicity with an approximately zero water contact angel (WCA) and underwater superoleophobicity with an underwater oil contact angel (UWOCA) greater than 150°. The compressed CA-PEI-MS showed an excellent oil-in-water emulsion separation performance with a separation efficiency greater than 97% and a water flux of up to 25,480 L h−1 m−2 bar−1. The recyclability test was used to study the stability of the compressed CA-PEI-MS, after washing with acetone; the flux did not show any significant change during the 12-cycle separation test. The separation efficiency in every cycle was greater than 97%. Due to the availability of rich positive charged amino groups, the as fabricated CA-PEI-MS exhibited adsorption ability towards negatively charged dyes such as, rose bengal (RB) and direct red (DR) with 96% adsorption efficiency. Therefore, the as designed low-cost and eco-friendly preparation of CA-PEI-MS has a great potential for practical application as it shows high separation performances and excellent efficiency. Image, graphical abstract l Caffeic acid-polyethyleneimine-modified melamine sponge (CA-PEI-MS) were fabricated by a simple method. l As-prepared CA-PEI-MS shows superhydrophilicity and underwater superoleophobicity. l The compressed CA-PEI-MS shows an outstanding performance for oil-in-water emulsion separation. l The flux is up to 25,480 L h−1 m−2 bar−1 and the separation efficiency > 97% for emulsion separations. l CA-PEI-MS also shows highly selective adsorption ability of anionic dyes. [ABSTRACT FROM AUTHOR]

The One Health framework emphasizes the interconnectedness of humans, animals, and the environment but often remains focused on human health. Here we highlight how the evolutionary and ecological dynamics of aquatic parasites are crucial to our understanding of these connected health aspects, especially in the light of environmental changes. [ABSTRACT FROM AUTHOR]

Extensive development of new applications using graphene based materials such as graphene oxide (GO) increases its potential release and occurrence into aquatic environments, raising the question of its biological and ecological risks. As standardized single-species-based assays fail to highlight toxicological pathways implying interactions between organisms, the use of micro/mesocosms appears as a good solution to fill the lack of environmental realism inherent to these tests. In this work, experiments were achieved using microcosm systems to expose a reconstituted food chain to GO at environmentally-relevant concentrations (0.05 and 0.1 mg L−1). The trophic chain was composed of a consortium of algae and bacteria as primary producers, chironomid larvae as primary consumers and decomposers while larvae of the amphibian Pleurodeles waltii constituted the secondary consumers. Monitoring of multiple ecotoxicological and ecological endpoints allowed to observe changes in bacterial communities while no toxic effects were noticed in chironomids. However, chironomids feeding behaviour changed as a consequence of GO contamination, leading to an increase in leaf litter consumption. Genotoxic effects were noticed in Pleurodeles larvae. This study highlights the importance of using such experimental systems to better encompass the ecotoxic potential of GO through the determination of toxicological routes and consequences on ecosystem's functioning. Image 1 [ABSTRACT FROM AUTHOR]

• A significantly divergent response of endangered waterbird to changes in hydrological connectivity was firstly found. • Endangered waterbirds are primarily affected by changes in water temperature and fish abundance. • Restoring the way hydrological connectivity has a negative effect on the recovery of endangered waterbirds' habitats. The Scaly-sided Merganser (SSME) is a globally endangered waterbird species, primarily inhabiting rivers. In recognition of its precarious status, it was added to the International Union for Conservation of Nature's (IUCN) Red List of Threatened Species in 2002. The SSME is highly sensitive to ecological environmental changes driven by changes in hydrological connectivity, particularly within riverine habitats. Changbai Mountain, a high-latitude water tower in the Northeast Asia, is considered one of the most optimal breeding grounds for the SSME worldwide. Its extensive water system and dense primary forest create an environment particularly well-suited for this species. Over the past 40 years, rivers within Changbai Mountain have experienced phases of hydropower development and ecological restoration. These activities have dramatically altered the hydrological connectivity of the area. However, the response of SSME to these changes in aquatic ecology, driven by shifts in hydrological connectivity, remains uncertain. We employed the AutoRegressive Integrated Moving Average (ARIMA) model to analyze changes in the population size of the SSME. Furthermore, the GeoDetector model was used to understand the impact of ecological changes on the maximum population size (MPS) and distribution of SSME in the context of alterations in hydrological connectivity. Our findings reveal that the restoration of hydrological connectivity, a method of ecological restoration, exerts a bidirectional influence on both the distribution and the MPS of SSME. Our findings can be summarized as follows. Firstly, there was a general trend of increase in both the distribution points and population size of the SSME. Secondly, the contribution of driving factors to the MPS of SSME was ranked in the following order: temperature > Connectivity Status Index (CSI) > river width > fish abundance > river depth > velocity > altitude > forest type. Thirdly, the impacts on the distribution and MPS of SSME were not due to a single factor, but rather a complex interplay of multiple factors. Finally, the construction of small hydropower stations significantly disrupted the hydrological connectivity of rivers, thereby altering the natural habitat of the SSME. The reduction in fish population, resulting from the loss of hydrological connectivity, adversely affected the MPS. Conversely, an increase in water temperature due to loss of hydrological connectivity positively impacted the MPS. However, these effects displayed heterogeneity across different rivers. Our study suggests that the construction of gravel dams may be a suitable approach in certain sections of the river, with a recommended height limit of 1.5 m. This research provides valuable insights for managers, offering a sustainable foundation for future energy planning and ecological restoration efforts. [ABSTRACT FROM AUTHOR]

[Display omitted] • The community structure of planktonic and benthic diatoms exhibited significant variations. • The biodiversity of planktonic and benthic diatoms showed exhibited significant variations. • The dispersal limitation dominated the assembly of planktonic and benthic diatom communities. • The dispersal limitation contributes more to the benthic diatom community assembly. Diatoms are an indispensable component of river ecosystem biodiversity and play an important role in aquatic ecosystems. The community assembly mechanism of diatoms has always been a central issue in the study of aquatic ecology. In recent years, many measures have been implemented in the Ashi River Basin (ASRB) to promote social and economic development, such as bridge construction, river bottom sand mining, agricultural irrigation, and urban expansion. However, there are few studies on the effects of these activities on the mechanism of diatom community assembly. First, we found that the α- and β-diversity of planktonic diatoms was higher in the normal season, while the α- and β-diversity of benthic diatoms was higher in the dry season, and the α- and β-diversity of both planktonic and benthic diatoms was reduced in the wet season. Second, the community structures of planktonic and benthic diatoms were significantly different in different hydrological periods, and the differences between planktonic diatoms communities were more evident than those between benthic diatom communities. Third, distance-decay analysis indicated that the distribution of the two types of diatom communities in the ASRB was influenced by both dispersal limitation and environmental selection. Finally, variance partitioning analysis revealed that dispersal limitation was the dominant driving factor for the spatial and temporal differentiation of planktonic and benthic diatoms. Our study reveals the important role of dispersal limitation in the community assembly of planktonic and benthic diatoms in rivers under different hydrological conditions. This study provides new insights for further understanding the relative importance of niche theory and neutral theory to aquatic microbial community assembly. Our research provides key information for analysing the structure of aquatic ecosystems and basic data for designing biodiversity conservation strategies in China's cold watersheds. [ABSTRACT FROM AUTHOR]

Research on the order Saprolegniales (Oomycota) has been an ongoing quest for more than a century. The best studied genera are Saprolegnia and Aphanomyces , known for their pathogenicity on freshwater animals. In this study, we reviewed 1073 papers and 2803 ITS sequences of Saprolegniales to investigate their taxonomy, diversity and potential roles in mainly freshwater ecosytems. We found that, in general, our knowledge on diversity and ecology of Saprolegniales is limited. Neither classic taxonomy nor available molecular techniques have been sufficient to delineate genera and species and show their relative distribution in freshwater-associated habitats. Also, we currently lack a comprehensive understanding of their involvement in carbon turnover and food web dynamics. Finally, due to lack of using high-throughput sequencing techniques, it is not clear how and to what extent communities of Saprolegniales might differ in freshwater econiches. Therefore, we provide a historical perspective on the establishment of Saprolegniales , explain improvements, highlight deficiencies, and finally propose new research avenues for more systematic studies. We conclude that challenges in studying Saprolegniales can be removed by increasing the practicality of classic taxonomy and applying available molecular toolboxes (multi-gene phylogeny and high-throughput sequencing). Additionally, inclusion of Saprolegniales in freshwater carbon cycling should be addressed for their better ecological resolution. • The real diversity and ecology of freshwater Saprolegniales is greatly unknown. • Multi-gene phylogeny should be able to resolve and delineate ambiguous taxa. • High-throughput sequencing will show any habitat-specificity in Saprolegniales. • Saprolegniales are involved in freshwater carbon cycling and food webs. [ABSTRACT FROM AUTHOR]

• We first report regime shifts in phytoplankton RUE along TSI gradient across space and time. • Tipping point values of TSI were lower in subtropical than temperate waterbodies. • Regime shifts regulated trophic transfer efficiency from phytoplankton to zooplankton. • Nitrogen-fixing filamentous cyanobacteria can drive eutrophication under mesotrophic state. • Early management practices for algal bloom prevention and control were latitude-dependent. Eutrophication and harmful algal blooms have severe effects on water quality and biodiversity in lakes and reservoirs. Ecological regime shifts of phytoplankton blooms are generally thought to be driven by the rapidly rising nutrient use efficiency of bloom-forming species over short periods, and often exhibit nonlinear dynamics. Regime shifts of trophic state, eutrophication, stratification, and clear or turbid waters are well-studied topics in aquatic ecology. However, information on the prevalence of regime shifts in relationships between trophic states and phytoplankton resource transfer efficiencies in ecosystems is still lacking. Here, we provided a first insight into regime shifts in nitrogen use efficiency of phytoplankton along the trophic state gradient. We explored the regime shifts of phytoplankton resource use efficiency and detected the tipping points by combining four temporal or spatial datasets from tropical to temperate zones in Asia and Europe. We first observed significant abrupt transitions (abruptness > 1) in phytoplankton nitrogen use efficiency along the trophic state gradient. The tipping point values were lower in subtropical/tropical waterbodies (mesotrophic states; TSIc: around 50) than those in temperate zones (eutrophic states; TSIc: 60–70). The regime shifts significantly reduced the primary production transfer efficiency via zooplankton (from 0.15 ± 0.03 to 0.03 ± 0.01; mean ± standard error) in the aquatic food web. Nitrogen-fixing filamentous cyanobacteria can drive eutrophication under mesotrophic state. Our findings imply that the time-window of opportunity for harmful algae prevention and control in lakes and reservoirs is earlier in subtropical/tropical regions. Conceptual scheme showing the trophic state index-dependent trend of nitrogen use efficiency of phytoplankton in the subtropical (red) and temperate (blue) zones. Tipping points were lower in the subtropical zones. [Display omitted] [ABSTRACT FROM AUTHOR]

ZIF-8, a sort of zeolitic imidazolate frameworks (ZIFs), had showed superior adsorptive property of typical radionuclide U(VI), but it reminded uncertain how the performance of ZIF-8 would be affected by adding humic acid (HA). HA could significantly change the surface charge of ZIFs and the transport of U(VI) in natural settings, which affected the eradication of U(VI) in aquatic ecology. Thus the impact of HA for the U(VI) removal by ZIF-8 as well as its mechanism had been analyzed by batch experiments and spectral analyses. It was demonstrated that the addition of HA increased the maximum removal capacity towards U(VI) from 781.2 mg g−1 to 1398.5 mg g−1. Moreover, removal property in acidic solution was improved, and the influence of background ions on ZIF-8 was reduced. The detailed mechanism was further explored by microscopic spectral analysis. The zeta potential showed that HA enhanced the electronegativity of ZIF-8 thus enhancing the electrostatic interaction with positive ions. Moreover, FT-IR and XPS further indicated that HA enhanced the removal capacity by affecting the surface complexation phenomena and strong chemical interactions between U(VI) and ZIF-8. Also, investigations indicated that the incorporation of HA improved the removal efficiency for U(VI), which had far-reaching significance for the application of ZIF-8 in practical environment. [Display omitted] • The effect of humic acid on the physicochemical properties of ZIF-8 was studied. • A fresh thinking for future research in practical application are prompted. • The influence of HA on the adsorption of uranium by ZIF-8 was studied. • The mechanisms are surface complexation and electrostatic interactions. • HA as a natural substance is more environmentally friendly in wastewater treatment. [ABSTRACT FROM AUTHOR]

• Activated Lagerstroemia speciosa seeds hull biochar (CLSHB) was prepared. • CLSHB was used for ofloxacin (OFL) adsorption. • Maximum uptake capacity of CLSHB was 34.60 mg/g. • Phyto-toxicity study indicates the reduction of OFL toxicity after adsorption. • Fabrication cost of CLSHB was found to be 8.7 $/kg. Water pollution by pharmaceutical pollutants such as antibiotics are rising day by day and antibiotics are considered as emerging contaminants because of their eventual threats for both human health and aquatic ecology. Recently waste biomass derived biochar has drawn a lot of attention, especially as adsorbents, for antibiotics contaminated wastewater sequestration because of their high sorption capability, higher surface area, and microporosity. In this study, waste biomass (Lagerstroemia speciosa) seed coats were used to produce biochar (CLSHB) through a pyrolysis progression followed by chemical activation with NaOH for the effective removal of an antibiotic drug ofloxacin (OFL) from water. The surface area, and pore volume of CLSHB were assessed to be 82.192 m2/g, and 0.189 cm3/g, consecutively. The optimum removal percentage of OFL was obtained to be 91.43 % at solution pH 5.0, adsorbent dose of 1.0 g/L, OFL concentration of 20 mg/L, and sonication time of 90 min. The OFL adsorption data were well-fitted by the Langmuir isotherm model with uptake capacity of 34.60 mg/g, which depicts the monolayer adsorption of OFL onto the CLSHB surface. OFL adsorption kinetics results fit to the pseudo-second-order model, indicating that chemical sorption might be the main mechanism by which the pharmaceutical adhered to the CLSHB surface. The phytotoxicity assessment demonstrated that the treated OFL solution obtained in this process was deemed suitable for seed germination and the total synthesis cost of CLSHB was found to be only 8.7 $/kg. The OFL elimination efficacy with CLSHB decreases from 91.43 % to 73.26 % after fifth cycle of consecutive use, demonstrating the strong stability and reusability of CLSHB. [ABSTRACT FROM AUTHOR]

Bacterial communities inhabiting sediments in coastal areas endure the effect of strong anthropogenic pressure characterized by the presence of multiple contaminants. Understanding the effect of pollutants on the organization of bacterial communities is of paramount importance in order to unravel bacterial assemblages colonizing specific ecological niches. Here, chemical and molecular approaches were combined to investigate the bacterial communities inhabiting the sediments of the Ichkeul Lake/Bizerte Lagoon, a hydrological system under anthropogenic pressure. Although the microbial community of the Ichkeul Lake sediment was different to that of the Bizerte Lagoon, common bacterial genera were identified suggesting a lake-lagoon continuum probably due to the hydrology of the system exchanging waters according to the season. These genera represent bacterial "generalists" maintaining probably general biogeochemical functions. Linear discriminant analysis effect size (LEfSe) showed significant differential abundance distribution of bacterial genera according to the habitat, the pollution type and level. Further, correlation analyses identified specific bacterial genera which abundance was linked with pesticides concentrations in the lake, while in the lagoon the abundance of specific bacterial genera was found linked with the concentrations of PAHs (Polycyclic aromatic hydrocarbons) and organic forms of Sn. As well, bacterial genera which abundance was not correlated with the concentrations of pollutants were identified in both lake and lagoon. These findings represent valuable information, pointing out specific bacterial genera associated with pollutants, which represent assets for developing bacterial tools for the implementation, the management, and monitoring of bioremediation processes to mitigate the effect of pollutants in aquatic ecosystems. Image 1 • Evidence of bacterial continuum in Ichkeul Lake/Bizerte Lagoon. • The lake and the lagoon have specific bacterial assemblages. • Each type of pollutant is associated with specific bacterial genera. • Uncontaminated sediments have also specific bacterial genera. • Potential to develop tools for managing bacterial resources. [ABSTRACT FROM AUTHOR]

Highlights • Nyl, Mogalakwena & Limpopo rivers are vital for the semi-arid Limpopo Province, South Africa. • South African freshwater biodiversity significantly underrepresented in ecological literature. • Includes high taxonomic resolution that is often lost in traditional monitoring efforts. • Provides a baseline for future aquatic monitoring and management in southern Africa. • Validates the use of macroinvertebrates to discern water quality of riverine ecosystems. Abstract Rivers are amongst the most threatened ecosystems on the planet. They are particularly susceptible to common forms of anthropogenic influences including sewage effluent runoff and flow modification. We hypothesized that the diversity of aquatic macroinvertebrate communities from three rivers (Nyl, Mogalakwena and Limpopo) within a semi-arid region (Limpopo, South Africa) will decline in response to shifts in water quality resulting from sewage effluent runoff. We assessed the diversity of aquatic macroinvertebrate communities from ten sites using univariate and multivariate analyses, and community responses were determined based upon anthropogenic disturbances. Our results show distinct spatial and temporal variation between the sampling sites and their associated macroinvertebrate communities. Spatial separation is attributable to increased concentrations of nitrogenous-based pollutants (total nitrogen and nitrites) and manganese, both of which are associated with sewage effluent runoff released by the Modimolle Waste Water Treatment Facility. Temperature is the principle driver of temporal variation amongst the macroinvertebrate communities, with winter (June 2016) communities being more diverse than summer (February 2017) communities. Macroinvertebrates remain important bioindicator organisms for riverine ecosystems, specifically within semi-arid regions. Our study highlights the need for more comprehensive diversity assessments of riverine macroinvertebrates, specifically from southern Africa, a region of the world that remains significantly underrepresented in the scientific literature of aquatic ecology. These results further increase our understanding of aquatic biodiversity within semi-arid regions and provides a baseline for future monitoring efforts and management in South Africa. [ABSTRACT FROM AUTHOR]

Abstract Water quality of river Ramganga, a major tributary of the Ganga, was monitored by monthly sampling at selected 23 stations (17 on the main stem and 6 on tributaries) during two calendar years 2014 and 2015 for 24 parameters. Cluster analysis grouped the sites in three statistically significant clusters, highly polluted, moderately polluted and less polluted, based on the similarities or differences in water quality parameter values. Discriminant Analysis helped in identifying the most representative discriminant parameters in entire dataset with more than 86% correct assignment in both temporal and spatial analysis. Despite high organic load in the middle stretch of Ramganga, the observed dissolved oxygen values were higher than 4 mg/l at almost all sampling stations on the main stem, even in lean flow period of a year. About 16–49% BOD load reduction from various point sources was estimated to maintain the desired dissolved oxygen levels (5–6 mg/l) for aquatic species during lean flow season in river Ramganga. This implies that primary treatment alone of discharge from these sources is sufficient from the point of view of sustenance of indigenous aquatic flora and fauna. Comparison of water quality of Ramganga and Ganga (before and after the confluence with Ganga) for lean flow season revealed that Ramganga does not significantly contribute to the decline in water quality of river Ganga in terms of parameters such as dissolved oxygen and heavy metals. Highlights • Discriminant analysis identified 6 parameters with more than 86% correct assignment. • Observed DO values were found higher than 4 mg/l at all sampling stations on main stem. • Reduction of 31%, 30%, and 49% BOD loads to maintain DO values more than 6 mg/l. • Dhela and Kosi are the most polluted tributaries of Ramganga. • Ramganga does not significantly contribute to the decline in water quality of Ganga. [ABSTRACT FROM AUTHOR]

Highlights • Macroinvertebrate taxa are assessed as surrogates of aquatic biodiversity in Africa. • We found congruence among their patterns of species richness and composition. • Higher-taxa (mainly genus) can be used to predict species diversity. • We propose the use of Ephemeroptera and Coleoptera at genus level as surrogates. Abstract The need to use surrogates of biodiversity is quite relevant in threatened habitats harboring high values of biodiversity, such as the Mediterranean aquatic ecosystems. In this study, we assess the performance of eight macroinvertebrate groups (Coleoptera, Heteroptera, Odonata, Trichoptera, Plecoptera, Ephemeroptera, Crustacea, and Mollusca) as surrogates of the whole aquatic macroinvertebrate assemblage in 49 localities from Northern Africa (Tunisia). Specifically, we aimed to test i) the congruence of the patterns of species richness and composition among these eight groups (at species level) in order to propose which groups could be accurate as indicators of diversity of the whole community, and ii) if higher-taxon levels (genera or families) are suitable for predicting overall species richness and composition in these ecosystems. In total, we found 72 families, 157 genera and 280 species. Our results show a high congruence between the patterns of species richness and composition of Ephemeroptera, Coleoptera (even at higher taxonomic levels, especially genus) and the whole community. Thus, we recommend the use of these two groups as surrogates of macroinvertebrate diversity in inland aquatic ecosystem in the study area. They can be used for both i) the rapid and inexpensive monitoring of biodiversity in aquatic ecosystems and ii) conservational studies in order to identify areas with the highest values of freshwater biodiversity in Mediterranean areas. Finally, high values of congruence among taxonomic levels were found suggesting that, in general, higher taxa can be used as biodiversity surrogates for cost-effective practical survey in Mediterranean aquatic ecosystems from Northern Africa. [ABSTRACT FROM AUTHOR]

Highlights • Phytoplankton community highly varied among sub-basins and hydrological periods. • Medium density residential land use acted as a critical driver during wet period. • The skewness of 7 days discharge emerged as a key driver for benthic diatom. • Microcystis was more closely related to phosphorous and lacustrine zone. Abstract Rivers and related freshwater ecosystems are facing increasing natural disturbance and anthropogenic stressors. Understanding the key ecological processes that govern the riverine biota in aquatic ecosystems under multiple pressures has crucial importance. However, there is still insufficient knowledge in quantifying of stressors interactions. Moreover, the understanding of the responses of riverine phytoplankton to multiple stressors is still scarce from catchment aspect. As an interdisciplinary study, the catchment hydrological processes were linked to ecological responses in this study, and we chose phytoplankton functional groups (PFGs) instead of taxonomic classifications of algae to examine their responses to land-use pattern (L), hydrological regime (H), and physicochemical condition (P) across two contrasting hydrological periods (dry, wet). The traits-based phytoplankton functional groups are highly suggested as robust bio-indicators for better understanding the current ecological status. The hydrological regime was described by a matrix indices of hydrological alteration based on the outputs of a well-established ecohydrological model (SWAT). The results from variation partitioning analysis showed that P and H dominate during the dry period and P in high flows. Structural equation models (SEM) showed that the skewness of 7 days discharge emerged as a key driver of H, and had always an indirect effect on functional group TB (benthic diatoms) during both hydrological periods. The functional group M (mainly composed by Microcystis) has directly related to phosphorous in both periods, while indirectly to L of urban area in high flow period, and water bodies in low flow period. This study emphasized that climate change and anthropogenic activities such as altering flow regime and land-use pattern affect directly or indirectly riverine phytoplankton via physicochemical conditions. In addition, our findings highlighted that biomonitoring activities require detailed investigation in different hydrological periods. SEM is recommended for improved understanding of phytoplankton responses to the changing environment, and for future studies to fulfill the increasing demand for sustainable watershed management regarding aquatic biota. [ABSTRACT FROM AUTHOR]

• An adaptive data assimilation method to update hydrodynamic model of shallow rivers. • Assimilation of multi-sensor, multi-modal water temperature observations. • The proposed technique improved model performance and reduced computation time. There is lack of knowledge in assimilation of multi-sensor, multi-modal water temperature observations into hydrodynamic models of shallow rivers, specifically, (a) how does accuracy of shallow river model improve after assimilation of in-situ and remotely sensed temperature observations, and (b) how can data from disparate sensors and sources be assimilated into the prediction model without significant increase in computational burden. Multi-sensor, multi-modal observations used in this study are obtained from in-situ monitoring devices in the river with limited spatial coverage but dense temporal resolution, and from Landsat-7 satellite that has better spatial coverage but limited temporal coverage. Use of remotely-sensed observations from satellites poses the challenge that the physical region represented by satellite data does not directly correspond with the physical domain of the river simulated in hydrodynamic models. Satellites detects the skin water temperature, whereas numerical models estimate the bulk temperature in the surface layer that may be multiple meters in thickness. Furthermore, for rivers narrower than the resolution of satellite data, the temperature of each cell represents the weighted average temperature of land and water. These factors introduce biases into the updated numerical model, thereby impeding appropriate management of temperature, water quality, and aquatic ecology. We implemented an efficient ensemble Kalman filter method using Latin-hypercube sampling to assimilate multi-sensor water temperature observations into the hydrodynamic model of the Lower Klamath River located in northern California. Assimilation of remote sensing data from Landsat-7 improved the model prediction for the entire river. The average spatial error was reduced from 2.59 °C to 0.66 °C (i.e., 75% improvement). In-situ data assimilation reduced the error at the observation location, however, error in the water temperature predicted by the updated model reverted in less than two days to the same level as that of an un-updated model. On the other hand, it is not computationally efficient to assimilate all of the available data into the model as they become available. In order to overcome these challenges, in-situ data were adaptively assimilated into the model whenever the error exceeded a maximum allowable error. Adaptive assimilation of in-situ data for the Lower Klamath river application occurred one to three times per day, and reduced the average daily error up to 58% compared to assimilation of in-situ data only once each day. [ABSTRACT FROM AUTHOR]

Abstract Chemical analysis of pollutants in environmental matrices cannot always offer powerful evidence on their impact and toxicity on the aquatic biota. This paper reports the ability of Potamogeton pusillus to highlight in an aquatic ecosystem those sites with higher environmental degradation through an active biomonitoring. Organisms were exposed for 96 h in seven sites along a river where variation in pollutants mixtures and levels could be expected due to different pollution sources. Different anthropogenic activities favoured the presence of pharmaceutical compounds along the basin (atenolol and carbamazepine showed the highest levels in water) as well as metals in water (Pb, Al, As, B, Hg) and sediments (Hg) surpassing local and international environmental guidelines. Through several biomarkers responses, P. pusillus showed sensitivity when exposed to different environmental scenarios and succeeded indicating the most contaminated sites. An integrative biomarker response index (IBR) confirmed to be a useful tool to obtain a holistic interpretation of response expressed by organism despite being little used for macrophyte studies. The Principal Components Analysis (PCA) analysis showed consistently a positive association between the IBR and pollutants concentrations, being this linkage strongest when a higher compounds levels occurred in the basin (cold period). Moreover, multivariate analysis indicated that IBR values were boosted when the concentration of metal in water and in the bioavailable fraction of sediments, increased. Finally, the obtained results indicate that the use of P. pusillus in combination with chemical analysis could be considered a promising tool for environmental management of aquatic ecosystems contaminated by multi-source. Graphical abstract Image 1 Highlights • Potamogeton pusillus proved to be a good tool for active biomonitoring. • Macrophyte stress was associated with Cr, Cu, Cd, Pb and Al concentrations. • Macrophyte stress was associated with total pharmaceuticals concentration in water. • Hg in sediments, Pb, Al, As, B, Hg in water, surpassed environmental guidelines. • First report of integrated biomarker response for a macrophytes active biomonitoring. [ABSTRACT FROM AUTHOR]

Abstract Oxytetracycline (OTC) is a broad-spectrum antibiotic widely used in livestock production. Like many other pharmaceuticals, OTC is not completely metabolized by the organism and thus, increasing amounts of the compound are being detected in the aquatic environment. The assessment of the environmental risk of pharmaceuticals is hindered by their very low concentrations and specific modes of action and thus relevant exposure scenarios and sensitive endpoints are needed. Thus, this work aimed to study the long-term effect of OTC exposure in zebrafish (at behavior and biochemical levels) and associated bacterial communities (fish gut and water bacterial communities). Results revealed that at behavioral level, boldness increase (manifested by increased exploratory behavior of a new environment) was observed in fish exposed to low OTC concentrations. Moreover, changes in fish swimming pattern were observed in light periods (increased stress response: hyperactivity and freezing) probably due to photo-sensibility conferred by OTC exposure. Effects at biochemical level suggest that long-term exposure to OTC interfere with cellular energy allocation mainly by reducing lipids levels and increasing energy consumption. Moreover, evidences of oxidative damage were also observed (reduced levels of TG, GST and CAT). The analysis of water and gut microbiome revealed changes in the structure and diversity of bacterial communities potentially leading to changes in communities' biological function. Some of the effects were observed at the lowest concentration tested, 0.1 μg/L which is a concentration already detected in the environment and thus clearly demonstrating the need of a serious ecotoxicological assessment of OTC effects on non-target organisms. Graphical abstract Image 1 Highlights • Zebrafish exposed to oxytetracycline present different feeding behavior pattern. • Oxytetracycline induced fish boldness and hyperactivity in light periods. • Energetic reserves and oxidative stress enzymes decrease after long-term exposure. • Bacterial communities of fish gut and exposure water were affected by oxytetracycline. [ABSTRACT FROM AUTHOR]

Abstract Exposure science, in its broadest sense, studies the interactions between stressors (chemical, biological, and physical agents) and receptors (e.g. humans and other living organisms, and non-living items like buildings), together with the associated pathways and processes potentially leading to negative effects on human health and the environment. The aquatic environment may contain thousands of compounds, many of them still unknown, that can pose a risk to ecosystems and human health. Due to the unquestionable importance of the aquatic environment, one of the main challenges in the field of exposure science is the comprehensive characterization and evaluation of complex environmental mixtures beyond the classical/priority contaminants to new emerging contaminants. The role of advanced analytical chemistry to identify and quantify potential chemical risks, that might cause adverse effects to the aquatic environment, is essential. In this paper, we present the strategies and tools that analytical chemistry has nowadays, focused on chromatography hyphenated to (high-resolution) mass spectrometry because of its relevance in this field. Key issues, such as the application of effect direct analysis to reduce the complexity of the sample, the investigation of the huge number of transformation/degradation products that may be present in the aquatic environment, the analysis of urban wastewater as a source of valuable information on our lifestyle and substances we consumed and/or are exposed to, or the monitoring of drinking water, are discussed in this article. The trends and perspectives for the next few years are also highlighted, when it is expected that new developments and tools will allow a better knowledge of chemical composition in the aquatic environment. This will help regulatory authorities to protect water bodies and to advance towards improved regulations that enable practical and efficient abatements for environmental and public health protection. Highlights • The role of modern analytical chemistry is essential in exposure science. • Hyphenation of chromatography and HRMS allows the identification of many organic contaminants in the aquatic environment. • Different strategies (target, suspect, non-target) are used for the broad investigation of emerging chemical risks in water. • Monitoring programs and risks assessments are normally focused on parent contaminants. • Little information exists on occurrence and (eco)toxicological effects of transformation products/metabolites in water. [ABSTRACT FROM AUTHOR]

Abstract In recent years, the rapid advances of culture-independent methods and new molecular tools have revolutionized our understanding of microbial biodiversity and ecological functions. DNA extraction from microbial communities is a critical step in this process and several methods have been proposed and used, but the influence of the extraction method on the outcome and ultimately on ecological inferences from the results is not yet precisely determined. Here, we compared two of the most commonly used extraction methods in aquatic microbial ecology, and investigated whether the two methods yielded comparable results for community ecology analyses. We extracted DNA from 15 different shallow lakes with phenol:chloroform, a classical and widely used extraction method, and with the PowerSoil DNA isolation Kit, often suggested as the standard DNA extraction method, with some adaptations for aquatic environments. We found that although only 5% of all OTUs showed significant differences in pairwise comparisons (using the 15 lakes as replicates), these OTUs accounted for >35% (on average) of the relative abundance. Diversity and richness did not differ significantly between the two extraction methods, but the beta-dispersion of the communities indicated that the organic extraction yielded more homogeneous communities, while the kit extraction generated variability. Consequently, we conclude that despite the small number of OTUs with significant differences, their impact on the community composition obtained was not negligible, and therefore the results from these two extraction methods were not comparable. Highlights • Two different extraction methods were compared. • Only 5% of all OTUs were significantly different in pairwise comparisons. • These OTUs represented >35% of total relative abundances. • Bacterial communities had similar diversity and richness, but different composition. • The results from these two extraction methods were not comparable. [ABSTRACT FROM AUTHOR]

Abstract The ecological risks of carbon nanotubes in the aquatic environment are of great concern. In this work, the effects of multi-walled carbon nanotubes (MWCNTs) on metabolic function of the microbial community in sediment contaminated with phenanthrene were investigated. The metabolic function was evaluated by Biolog ECO microplates a month later after MWCNTs of various dosages (0.5%, 1.0%, and 2.0%, w/w) were incorporated into the phenanthrene-contaminated sediment. The self-organizing map (SOM) algorithm and principal components analysis were used for data processing. The incorporation of 0.5% MWCNTs into the contaminated sediment significantly enhanced microbial activity (from 0.83 to 0.92, average well color development) and Shannon-Wiener diversity index (from 3.19 to 3.23) compared with the blank control. Clustering the microbial communities in different treatments on the trained SOM suggested that phenanthrene had a greater impact on the metabolic function of sediment microbial communities than MWCNTs in the experiments. The metabolic differences caused by MWCNTs were mainly reflected in the utilization of amino acids and polymers. The results of this study may contribute to evaluating the ecological risks of MWCNTs in the aquatic environment and developing the secure applications of MWCNTs. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract Microplastic (MP) pollution is an emerging issue in aquatic sciences. Little comparative information currently exists about the problem in coastal systems exposed to different levels of human impact. Here we report a year-long study on the abundance of MP in the water column of three estuaries on the east-coast of Australia. The estuaries are subject to different scales of human impact; the Clyde estuary has little human modification, the Bega estuary has a small township and single wastewater treatment works discharging to its waters, and the Hunter estuary which has multiple townships, multiple wastewater treatment plants, and heavy industry. MP abundance followed an expected pattern with the lowest abundance in the low-impact Clyde estuary (98 part. m3), moderate levels of MP in the moderately impacted Bega estuary (246 part. m3), and high MP abundance in the highly impacted Hunter estuary (1032 part. m3). The majority of particles were <200 μm and fragment-like rather than fiber-like. MP abundance was positively related to maximum antecedent rainfall in the Bega estuary, however there are no clear environmental factors that could explain MP variation in the other systems. MP were generally higher in summer and following freshwater inflow events. On the Hunter estuary MP abundance was at times as high as zooplankton abundance, and within the range of numbers reported in other highly impacted systems globally. The results confirm that higher levels of human impact lead to greater plastic pollution and highlight the need to examine aquatic ecosystems under a range of conditions in order to adequately characterize the extent of MP pollution in rivers and coastal systems. Graphical abstract Image 106356 Highlights • Microplastic abundance increased in estuaries with increasing human impact. • 68–76% of particles <200 μm. • The majority of microplastics were fragment-like rather than fibers. • Microplastic concentrations positively related to antecedent rainfall. Microplastic abundance is higher in estuaries with higher human impact. The microplastic pool was dominated by fragment like particles <200 μm in size. [ABSTRACT FROM AUTHOR]

Abstract The salinization of freshwater environments is a global concern, and one of the largest sources of salinated water is the mining industry. An increasing number of modern mines are working with low grade sulfide ores, resulting in increased volumes of potentially harmful saline drainage. We used water monitoring data, together with data on sedimentary fossil remains (cladoceran, diatom and chironomid), to analyze the spatio-temporal (5 sampling locations and 3 sediment depths) impact of salinated mine water originating from the Talvivaara/Terrafame open cast mine on multiple components of the aquatic ecosystem of Lake Jormasjärvi, Finland. Lake Jormasjärvi is the fourth and largest lake in a chain of lakes along the path of the mine water. Despite the location and large water volume, the mine water has changed the chemistry of Lake Jormasjärvi, reflected in increased electrical conductivity values since 2010. The ecological impact is significant around the inflow region of the lake, as all biological indicator groups show a rapid and directional shift towards new species composition. There is a clear trend in improved water quality as one moves further from the point of inflow, and as one looks back in time. Our results show that salinated mine water may induce rapid and large scale changes, even far downstream along a chain of several sinking basins. This is of special importance in cases where large amounts of waste water are processed in the vicinity of protected habitats. Graphical abstract Image 1 Highlights • Saline mine water has changed the Lake Jormasjärvi water chemistry. • The impact of mine water propagates through food web as diatom, cladoceran and chironomid assemblages have changed. • The mine water impact is clearest in southern part of the lake. • Our results are alarming because Lake Jormasjärvi is fourth lake in chain of lakes on the course of treated mine water. [ABSTRACT FROM AUTHOR]

Abstract Conflicts among and between local, national, regional and international stakeholders involved in marine turtle conservation are increasing. Often, they arise because of different socio-economic backgrounds of the people or groups involved. Here, we identified and assessed the conservation-based conflicts occurring in 24 of the 39 Caribbean countries, including their frequency, level of severity, number of stakeholders' groups involved, the degree to which they hinder conservation goals, and potential solutions. Using a cross-sectional social survey, we evaluated the presence and details of conservation conflicts provided by 72 respondents. The respondents included conservation-based project leaders, researchers, people involved in policy-based decision-making, conservation volunteers (community-based conservation groups), and species experts with experience working on marine turtle conservation programs in the Caribbean. The respondents identified 136 conflicts, and we grouped them into 16 different categories. The most commonly mentioned causes of conflicts were: 1) the 'lack of enforcement by local authorities to support conservation-based legislation or programs' (18%); 2) 'legal consumption of turtles by one sector of community clashing the conservation aspirations of other sectors of community (14%); and 3) 'variable enforcement of legislation to limit/prohibit use across range states of the species (10%). From our data it is also apparent that illicit activities in the region are also likely to impact the future success of conservation or monitoring based projects and programs. Overall, an exhaustive review was carried out, and the potential solutions were gathered. Due to the level of severity (physical violence) that some conflicts have reached, achieving solutions will be challenging without mediation, mutual cooperation around shared values, and adaptive management arrangements. Achieving this will require combinations of bottom up and top down collaborative governance approaches. Highlights • We identified up to 161 human-derived conflicts which are related to marine turtle conservation initiatives. • We found that each stakeholder group may have a unique perspective towards these conflicts, complicating enforcement. • Marine turtle consumption generates conflicts among stakeholders with different socio-cultural values. • We identified 27 cases that have escalated to a level of physical violence, according to details provided by our respondents. • We summarised potential solutions for these conflicts, along with possible solution implementations. [ABSTRACT FROM AUTHOR]

Abstract Monitoring dissolved nitrate (NO 3 −) concentrations is essential for conservation efforts in aquatic ecosystems. Spectrophotometric methods are a widely accepted approach for NO 3 − analysis. They detect NO 3 − as a colored diazo complex after reduction to nitrite (NO 2 −) and its consequent reaction with the so-called Griess reagent. This method is commonly used for freshwater and saline water samples, even though it requires applying a heavy metal in powder form (cadmium) or high concentrations of heavy metal salts (vanadium-III), as a reductant. There has been little discussion about applying these methods for hypersaline samples. This study optimizes an existing method for use in high saline conditions based on the Griess reaction. Five factors were studied: incubation temperature, reaction time, concentration of EDTA, concentration of trisodium citrate, and concentration of reductant (VCl 3). Optimal conditions were obtained by using the Box-Behnken design and included using VCl 3 17.5 mM, trisodium citrate 70 mM, and an incubation temperature of 60 °C for 40 min. These conditions provided a linear range from 0.55 μM to 50 μM NO 3 −. The method showed a moderate precision (ranging from 4.3% to 15.4%). The proposed protocol was tested with hypersaline natural samples and showed recovery rates between 92.6% and 100.1%. This protocol for NO 3 − determination is the first specifically described for hypersaline samples. Highlights • Nitrate determination in hypersaline waters was optimized. • A limit of detection of 0.55 μM NO 3 − was achieved. • Recovery rates in hypersaline natural samples were between 92.6% and 100.1%. [ABSTRACT FROM AUTHOR]

Highlights • BSDs were estimated for >65% of the monitoring sites in Tokyo Bay and Ise Bay. • Low BSDs were observed in the innermost region of Tokyo Bay and Ise Bay. • BSD was positively correlated with salinity in Tokyo Bay and Ise Bay. • Phytoplankton's contribution in light attenuation was less than 40% in two bays. Abstract Region-specific background Secchi depth (BSD) provides valuable information on light availability in aquatic ecosystems. We estimated BSD in two eutrophic bays located in central Japan, Tokyo Bay and Ise Bay. Estimates were based on monitoring data collected in the period 1981–2015. Reliable BSD estimates were obtained for 89–96% and 67–94% of the monitoring sites in Tokyo Bay and Ise Bay, respectively. Low BSD values were obtained in the innermost sectors of Tokyo Bay (around the Nakagawa, Arakawa and Sumidagawa estuaries) and Ise Bay (around the Shonaigawa, Kisogawa and Ibigawa estuaries). BSD was positively correlated with salinity in both bays, indicating that river-supplied substances, including tripton and/or colored dissolved organic matter, strongly influenced BSD values. Although the highest chlorophyll a concentrations were measured in the innermost sectors of both bays, the proportional contribution of phytoplankton to light attenuation was surprisingly low in comparison with other sectors of the two water bodies. In both bays, phytoplankton accounted for <40% of light attenuation through the water column, indicating that background factors played a dominant role even in these highly eutrophic waters. Determinations of Secchi depth, BSD, and the proportional contributions of phytoplankton and background factors to light attenuation will improve understanding of the aquatic light environment, which in turn will inform the development of rational coastal management practices. [ABSTRACT FROM AUTHOR]

Abstract River biofilms play fundamental roles in shaping the architecture of aquatic systems. Sorption to biofilms was thought to be a crucial mechanism controlling the fate and transport of trace emerging contaminants. This study focused on the role of in situ colonized river biofilms in the early fate of phthalate esters (PAEs) and bisphenols (BPs) at trace concentrations in a representative urban river. PAEs and BPs were readily sorbed to biofilms with uptakes of 38.2–162.5 μg/g for PAEs and 1787.7–4425.6 μg/g for BPs, respectively. The total mass and characteristics of the colonized biofilms varied in response to seasons and water qualities. The biofilm colonized in the downstream of a wastewater treatment plant exhibited the highest sorption capacity among the tested sites, possibly attributed to the higher organic contents of biofilms owing to the elevated availability of nutrients. Correlation analysis indicates that certain water qualities, e.g., TN and NH 3 N, and biofilm properties, e.g., organic and polysaccharide fractions could be selected to predict the sorption capacities of river biofilms. Hydrophobic partitioning into organic matter appears to be the dominant sorption mechanism and biofilm polysaccharides were probably responsible for the adhesion of tested compounds. The contaminant partitioning into biofilm and sediment at mass/volume ratios typical for small rivers suggests that the biofilm could serve as an important sorbing matrix for the trace organic contaminants as compared to the sediments. Our work yields new insights into the early uptake and accumulation of trace plasticizers by natural biofilms, which is of significance in understanding the subsequent transport of trace organic contaminants in fluvial systems. Graphical abstract Image 1 Highlights • The mass and properties of colonized biofilms altered in response to spatial and seasonal variations. • River biofilm serve as important sink for phthalate esters and bisphenols, especially for bisphenols. • Polysaccharides appear to be key fractions responsible for sorption process. • The sorption mechanism analysis provides insights into the fate of plasticizers in fluvial systems. [ABSTRACT FROM AUTHOR]

Abstract Understanding recreational demand in aquatic ecosystems is necessary to relate ongoing environmental change to anthropogenic factors. We investigated whether factors influencing patterns of boating activity by recreational fishers (boat fishers) differed from those of other recreational boaters at Ontario, Canada lakes. Count data from aerial roving creel surveys flown for one year between 2008 and 2012 and across 643 lakes in Ontario indicated that greater accessibility of lakes, lake size, and human development around lakes were associated with higher activity for both boat fishers and other recreational boaters. Other recreational boating activity was greater at lakes with more human development (as measured by the density of docks) and was more concentrated in southern Ontario than was boat fishing activity. Boat fishing activity was greater at larger-sized lakes with tourism establishments and greater walleye biomass densities and less within lakes located in parks than was other recreational boating activity. The reduced importance of human development and increased importance of walleye for boat fishers was associated with boat fishing having a greater spatial footprint than other recreational boating. This different footprint can result in different impacts from the two activities across a large area such as the province of Ontario. Although boat fishers travelled further afield than other recreational boaters, large lakes with tourism establishments were especially attractive to these fishers. Consequently, these lakes are especially susceptible to impacts from boat fishers including the arrival of non-indigenous species. The boat fishing and other recreational boating models had strong predictive power (correlation coefficient > 0.80) when validated with a separate evaluation dataset comprised of 456 lakes and activity counts measured between 2013 and 2017. [ABSTRACT FROM AUTHOR]

Abstract Graphene-related materials (GRMs) are one of the most attractive materials from an application perspective, consequently their release into aquatic environments is highly likely. In the present work, the potential of fish hepatocytes (topminnow fish hepatoma cell line, PLHC-1) and macrophages (carp leukocyte cell line, CLC) to study the toxicity and intracellular fate of helical-ribbon carbon nanofibers (CNFs) and graphene oxide (GO) used in a variety of intermediate industrial products was evaluated, allowing a first ranking of GRMs according to their cytotoxicity. Cells were exposed to a concentration range of 0–200 μg ml−1 of GRMs for 24 and 72 h and cell viability was assessed by measuring mitochondrial activity (AlamarBlue assay), plasma membrane integrity (5-carboxyfluorescein diacetate-acetoxymethyl ester assay) and lysosomal function (neutral red uptake assay). Results showed that both the cell type and the choice of endpoint determined the toxicity of GRMs. In both cell lines, CNFs appeared to have higher toxicity than GO and the highest degree of graphitization in fibers was associated with lower toxicity. Transmission electron microscopy revealed that CNFs were taken up into membrane-bound compartments of PLHC-1 cells in a size-independent manner, whereas in CLC, longer CNFs were encountered free in the cytoplasm and only the shorter CNFs were localized in membrane-surrounded vesicles. GO sheets were present within vesicles as well as free in the cytoplasm of both cell types. These findings contribute to the understanding of the toxicity and behaviour of these GRMs in living systems, therefore aiding in designing safer materials for the environment. Highlights • Current lack of knowledge about toxic mechanisms of graphene-related materials. • Two fish cell lines were used to generate initial ecotoxicity data of GRMs. • Carbon nanofibers (CNFs) showed higher toxicity than graphene oxide (GO). • The presence of CNFs and GO inside vesicles was cell and size dependent. • CNFs toxicity was inversely related to the graphitization degree. [ABSTRACT FROM AUTHOR]

Abstract With the phasing out of brominated flame retardants, organophosphate flame retardants (OPFRs) have been widely used and further detected in multiple environmental media. However, municipal landfill leachates, an important source of contamination of OPFRs to aquatic environment, have not been fully understood, especially in a developing country like China. Thus, the occurrence, aqueous removal efficiency, environmental emission, and risk assessment of 10 OPFRs were investigated in leachates from six municipal landfills across China. The results indicated that except triethyl phosphate (TEP), the remaining 9 OPFRs were detected in both raw and final leachates with different frequencies higher than 33.3%. The range of total concentrations of OPFRs (ΣOPFRs) across China was 29.0–437 and 0.652–32.4 μg L−1 in raw and final leachates, respectively. Tris(2-chloroethyl) phosphate (TCEP) was the dominant species and accounted for 78.5% and 85.8% of average ΣOPFR concentration in raw and final leachates, respectively. This may be because TCEP is the most prevalently used OPFR in China. The overall aqueous removal efficiency of ΣOPFRs across China ranged from 57.7% to 99.8%. Tris(2-butoxyethyl) phosphate was the most removed species (98.8%), whereas TCEP was the least removed species (91.5%). The annual emissions of ΣOPFRs discharged into the aquatic environment from municipal landfills across China were estimated to be between 170 and 7094 g. Further risk assessment based on risk quotient values in the final leachates showed that most OPFRs posed negligible risk except TCEP (medium and high risk) and tributyl phosphate (medium risk). Graphical abstract Image 1 Highlights • Concentrations of 10 OPFRs in landfill leachates across China were determined. • Nine of the 10 OPFRs were frequently detected in both raw and final leachates. • The OPFRs have high removal efficiency during the leachate treatment process. • TCEP and TNBP in final leachates pose medium to high ecological risk. [ABSTRACT FROM AUTHOR]

Abstract An influx of chloride ions from road de-icing solutions can result in toxicological effects to organisms in terrestrial and aquatic environments. As such, "eco-friendly" de-icing alternatives are sought to mitigate environmental impacts of de-icing impervious surfaces, while maintaining human safety. While many alternative de-icers are economically impractical for municipal use, the residential commercial market is flooded with de-icing formulations claiming to be "eco-friendly". Given the little regulation and guidance that surrounds eco-labeling, the meaning of "eco-friendly" remains unclear in the context of biological systems. The objective of the current study was to determine the toxicity of three "eco-friendly" de-icing formulations to Chironomus dilutus using 10 d toxicity tests. The toxicity of these three formulations was compared to a traditional formulation composed entirely of chloride salts. Two of the "eco-friendly" de-icers demonstrated LC 50 s of 6.61 and 6.32 g/L, which were similar in toxicity to the traditional sodium chloride formulation with a LC 50 6.29 g/L. The comparable toxicities of these formulations is likely due to the presence of chloride salts in each of the "eco-friendly" de-icers. The third "eco-friendly" formulation, a urea-based de-icer, demonstrated toxicity an order of magnitude higher than that of the traditional formulation with an LC 50 of 0.63 g/L. While C. dilutus may not have been the intended endpoint in consideration when marketing these products as "eco-friendly", consideration of how eco-labeling is utilized and the role of environmental scientists in determining the meaning of such claims must be considered to ensure continued and future protection of the environment. Graphical abstract Image 1 Highlights • Chloride salt de-icers pose risk to aquatic and terrestrial environments 12. • Eco-friendly de-icers reduce or replace chloride salts with alternative ingredients 13. • Eco-friendly de-icers were not protective of Chironomus dilutus 14. • Ambiguity in eco-friendly claims undermines such products in commercial markets 15. • A clearer definition of "eco-friendly" is required for green marketing to progress. Development of "eco-friendly" alternatives to chloride salt de-icers are purported to better protect aquatic and terrestrial environments while maintaining human safety, yet ambiguity in eco-friendly claims leads to difficulty in evaluating product safety for eco-conscious consumers. [ABSTRACT FROM AUTHOR]

Abstract Geochemical distribution of trace elements in sediments could reflect the impact of anthropogenic activities on environmental changes in aquatic ecosystems. In this study, rare earth elements (REEs) were used as geochemical tracers to study the environmental processes in a complex and dynamic aquatic environment. Both surface and core sediment samples were collected from Poyang Lake, the largest freshwater lake located in the middle-low region of the Yangtze River. Sediment samples were analyzed for their respective REE spatial distributions, fractionation, and co-occurrence patterns. The inner relationships and geochemistry characters of REEs were assessed by geostatistics and co-occurrence network analysis. Results indicated that total REE concentrations in the sediments from Poyang Lake ranged from 145.1 to 351.1 μg g−1, with an average concentration of 254.0 μg g−1. Light rare earth element (LREE, La - Sm) enrichment was evident in all sediment samples, indicating the effects of river-lake interactions and the contributions from terrestrial inputs. The negative Ce and Eu anomalies were found in most sediment samples, indicating the differentiation between Ce, Eu, and other REEs in the processes of sediment transportation and deposition. Collectively, the identification of the major contamination sources of REEs in sediment, analyzed by the patterns of the co-occurrence networks and REE fractionation, revealed that the REEs in sediments from Poyang Lake originated both natural and anthropogenic sources and were disturbed by the impact of anthropogenic activities. Graphical abstract Image Highlights • Accumulation and distribution of REEs in sediments from Poyang Lake were studied. • Obvious fractionation between LREEs and HREEs is observed in sediments. • A weak Ce and Eu anomalies were found in most of the sediments. • Co-occurrence and fractionation patterns of REEs were used for source identification. [ABSTRACT FROM AUTHOR]

Abstract Titanium dioxide (TiO 2) nanoparticles and bisphenol A (BPA) in aquatic environments interact reciprocally to enhance the maternal transfer of pollutants to offspring, thus varying the innate toxicities during early embryonic development. However, it remains unexplored regarding the molecular mechanisms of developmental toxicity in offspring after parental coexposure. In the present study, adult zebrafish were exposed to TiO 2 nanoparticles (100 μg/L), BPA (20 μg/L) or their binary mixture for four months. Then, eggs of F1 generation were collected and reared in clean water until 5 days post-fertilization. In characteristic of larval survival and growth, parental coexposure to TiO 2 particles and BPA caused a severer inhibition of F1 offspring larvae compared with single exposure. Mechanistic investigation by shotgun proteomics found that development of larval offspring from coexposed parents was impaired through a distinct mode of toxicity, that is, specifically altering the activity of phagosome and lysosome. Single exposure of adult zebrafish to TiO 2 mainly affected insulin-responsive compartment; and BPA parental exposure mainly affected carbohydrate metabolism and calcium signaling of larval offspring. Furthermore, considering the tight regulation of sex hormones in the expression of vitellogenin (VTG), addition of nanoparticles during parental exposure led to inconsistencies between VTG induction and endogenous levels of sex hormones (estradiol and testosterone) in F1 offspring fish. This implied that transfer of nanoparticles to offspring larvae may change the availability of hormonal molecules and BPA at target tissues. Overall, current results provided mechanistic clues into the multigenerational developmental toxicity by parental coexposure to TiO 2 particles and BPA. Graphical abstract Image 1 Highlights • Adult zebrafish were chronically exposed to TiO 2 nanoparticles, BPA or the mixture. • Mechanisms of developmental toxicity in offspring larvae were investigated. • Parental coexposure impaired the survival and growth of offspring. • Phagosome and lysosome activity were affected in larvae from coexposed parents. • TiO 2 in offspring may alter the availability of sex hormones in target tissues. [ABSTRACT FROM AUTHOR]

Abstract Nitrate is a ubiquitous component in aquatic environment and the concentrations of anthropogenic nitrate-nitrogen (NO 3 N) can exceed 25 mg/L in surface waters and 100 mg/L in ground waters. The exceed nitrate has adverse effects on survival, development, and metamorphosis of amphibian. Liver is the hub of many biological processes, including lipid metabolism and bile salts secretion. However, there is little information about the effects of nitrate on the liver in amphibians during metamorphosis. In this study, B. gargarizans was exposed to different concentrations of nitrate from embryo to metamorphosis climax to investigate the effects of nitrate on the liver. The survival rate, metamorphosis percent, body mass, total length, and hind-limb length were measured. The histopathological changes and transcriptome responses in the liver of B. gargarizans to nitrate were examined. Results indicated exposure to 50 and 100 mg/L NO 3 N delayed the metamorphosis and decreased the metamorphosis percent of B. gargarizans. The body size of B. gargarizans at 10 and 50 mg/L NO 3 N groups were decreased while it was increased at 100 mg/L NO 3 N group. In addition, exposure to 100 mg/L NO 3 N caused severe histopathological changes, including cellular atrophy, increased intercellular areas, degraded lipid droplets, hepatic fibrosis, bile canaliculus contraction and degraded mitochondria in liver. The results of RNA-seq and qRT-PCR interpreted the molecular responses, which might be the factors to induce histopathological changes in the liver of B. gargarizans under the pressure of nitrate exposure. Highlights • Nitrate could delay the metamorphosis and inhibited the growth of the B. gargarizans tadpoles. • Nitrate could cause severe histopathological changes in the liver. • The transcriptomic responses in liver may reveal the molecule mechanisms of the effects of nitrate on liver. [ABSTRACT FROM AUTHOR]

Abstract There is increasing knowledge about the presence of psychiatric pharmaceutical substances in the aquatic environment due to increasing number of ecotoxicological studies with sensitive species in addition to improved methods of analysis. Here, we assessed the effects of two psychiatric substances carbamazepine and fluoxetine in the planarian Schmidtea mediterranea using endpoints such as survival, behaviour (feeding, locomotion), DNA damage and regeneration. Also, planarian asexual reproduction by fissioning was used to assess the reproductive effects of these compounds. Whereas for survival, no effect was observed for carbamazepine exposure, fluoxetine exposure was toxic to planarians with an LC 50 of 357.93 and 160.01 μg L−1 at 48 and 96 h, respectively. Time for head regeneration in decapitated planarians was not affected by either fluoxetine or carbamazepine exposures. Fluoxetine was more toxic than carbamazepine and caused concentration dependent increase in locomotor activity and DNA damage (LOEC's of 0.1-1.0 μg L−1), and decrease in feeding and fissioning. Despite some alteration on planarian locomotion observed under exposure to intermediate concentrations, no significant effects were observed in the other endpoints in response to carbamazepine. The observations in the present study showed that freshwater planarians such as Schmidtea mediterranea , animal models in neuropharmacology, are sensitive to low concentrations of psychiatric drugs, displaying an array of sensitive sub-lethal endpoints that can be used for the ecological risk assessment of psychiatric substances. Future studies to determine effects of these psychiatric drugs on the levels of neurotransmitters and other biochemical biomarkers in planarians are recommended. Highlights • Freshwater planarians can be used for environmental risk assessment of psychiatric drugs. • Toxic effects of fluoxetine and carbamazepine were assessed in laboratory exposures. • Survival, behaviour, asexual reproduction, regeneration and genotoxicity were used as endpoints. • Fluoxetine is more toxic to Schmidtea mediterranea than carbamazepine. • S. mediterranea is more sensitive to fluoxetine than some aquatic invertebrates used in ecotoxicology. [ABSTRACT FROM AUTHOR]

Highlights • Comprehensive procedure to quickly seek biofactors responsible for metal sorption. • Flagellin of Serratia Se1998 demonstrated a super binding capacity towards Pb. • A potential remediation tool for Pb contamination in aquatic environment. Abstract Metal contaminants present persistent and deleterious threats to environmental ecosystems and human health. Microorganisms can rapidly develop protective mechanisms against metal toxicity, such as metallothionein production. The identification of biological factors related to these protective mechanisms is essential for effective metal remediation. This study presents a robust pathway to rapidly locate and characterize a Pb-binding flagellin in Serratia Se1998, which can bind Pb at a 16:1 Pb: protein ratio. A column gel electrophoresis system hyphenated with inductively coupled plasma mass spectrometry (ICP MS) was constructed to efficiently separate and identify Pb-binding proteins from the whole bacterial proteome. PCR and transgenic assays were used to elucidate the exact sequences and biological function of Pb-binding proteins and heterogeneous expression of Pb-binding flagellin in E. coli could significantly enhance Pb removal from aqueous solution by approximately 45%. This method provides a benchmark procedure to rapidly identify biological factors responsible for metal biosorption. Identification of this unique Pb-binding flagellin highlights that microorganisms can survive high metal stresses due to various complex biological pathways for metal detoxification and remediation. [ABSTRACT FROM AUTHOR]

Abstract Biofilms mediate crucial biochemical processes in aquatic ecosystems. It was hypothesized that eutrophication may promote the growth of biofilms, resulting in larger numbers of functional genes. However, the metabolic activity and the roles of biofilms in N cycling will be affected by ambient inorganic nitrogen availability, not by the abundance of functional genes. Biofilms were cultured either with replete inorganic nitrogen (N-rep) or without exogenous inorganic nitrogen supply (N-def) in a flow incubator, and the N-cycling gene abundances (nifH , N 2 fixation; amoA , ammonia oxidation, archaea and bacteria; nirS and nirK , denitrification) and enzyme activities (nitrogenase and nitrate reductase) were analyzed. The results showed that, comparing the N-def and N-rep biofilms, the former contained lower nifH gene abundance, but higher nitrogenase activity (NA), while the latter contained higher nifH gene abundance, but lower NA. Different patterns of NA diel variations corresponded to the dynamic microbial community composition and different stages of biofilm colonization. Ammonia oxidizing bacteria (AOB), detected only in N-def biofilms, were responsible for nitrification in biofilms. N-rep biofilms contained high nirS and nirK gene abundance and high denitrification enzyme activity, but N-def biofilms contained significantly lower denitrification gene abundance and activity. In general, the strong N 2 fixation in N-def biofilms and strong denitrification in N-rep biofilms assured the balance of aquatic ecosystems. The results suggested that evaluation of the functional processes of N cycling should not only focus on genetic potential, but also on the physiological activity of biofilms. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Highlights • Seasonality, and not diffuse loading drives eutrophication of a river-lake system. • Nutrient and phytoplankton cycles predominantly govern the upper, eutrophic system. • P & N cycles, diffuse loading, and DO balance regulate the middle reach. • Phosphorus release from sediments plays a key role in nutrient dynamics. Abstract Located on the same river, the degree of eutrophication in the upper and middle reaches of the Qu'Appelle River in Saskatchewan are different. While the upper Qu'Appelle is eutrophic, the middle Qu'Appelle River is hypereutrophic. To manage the river sustainably, there is a need to understand key processes governing eutrophication in both systems. In this study, a comprehensive global sensitivity analysis technique, Variogram Analysis of Response Surface (VARS), was applied to gain insights to the functioning of the two systems. Eutrophication in both systems was modelled using the Water quality Analysis Simulation Program (WASP 7.52). The performance of the model to predict key variables of eutrophication was measured using relative root mean square error. The global sensitivity analyses showed that although diffuse loading has significant influence on the systems, prevailing processes governing eutrophic state in the upper Qu'Appelle River include: nutrient and, phytoplankton cycles. Meanwhile, in the middle Qu'Appelle River a number of processes including phytoplankton cycle, nutrient cycle, diffuse loading and DO balance together sustain its hypereutrophic state. [ABSTRACT FROM AUTHOR]