The accumulation of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in aquatic environments has become increasingly severe, posing threats to both ecosystems and human health. Among them, perfluorooctanoic acid (PFOA), as a typical representative, its toxicity to aquatic organisms is particularly pronounced. However, effective strategies for mitigating PFOA toxicity and managing water quality remain insufficiently understood. To identify such strategies, this study used the indicator aquatic organism Nitzschia palea (N. palea) to investigate the potential of Albicanol in mitigating the adverse effects of PFOA on algal growth, morphology, and oxidative stress. The results showed that PFOA could cause cell deformation in N. palea, reduce cell density, decrease chlorophyll a content, and lower mitochondrial membrane potential. PFOA induced the accumulation of reactive oxygen species (ROS), which subsequently activated the mitochondrial apoptosis pathway, leading to cell death. However, Albicanol can enhance antioxidant enzyme activities and reduce ROS accumulation, thereby alleviating the decline in mitochondrial membrane potential and upregulating the expression of genes related to the mediation of apoptosis by mitochondria (NpCyt-C, NpCaspase3 and NpCaspase9), ultimately counteracting apoptosis induced by PFOA in N. palea. In summary, Albicanol can inhibit PFOA-induced apoptosis in N. palea cells, providing a theoretical basis for the management and ecological remediation of PFOA in aquatic environments.

Initial biomass is a key regulator of microalgal resilience to polystyrene microplastics (PS-MPs). This study investigated the responses of four microalgae-Chlorella sp., Scenedesmus sp., Cyclotella sp., and Spirulina sp.-exposed to 5 mg L-1 PS-MPs across biomass gradients of 500 - 1500 mg L-1. PS-MPs induced species- and density-dependent responses rather than uniform toxicity. Higher initial biomass increased final population yield and extracellular polymeric substance (EPS) production, but reduced specific growth rates due to intensified self-shading and resource competition. Chlorella sp. and Spirulina sp. exhibited stronger resilience, supported by pigment accumulation, coordinated antioxidant regulation, and EPS-mediated PS sequestration. Multivariate analysis further confirmed that biomass level, EPS secretion, photosynthetic performance, and oxidative status collectively structured microalgae-PS interactions. Notably, an initial biomass of 1000 mg L-1 provided the optimal balance between growth performance and remediation efficiency. These findings provide a quantitative framework for optimizing microalgae-based systems for microplastic contaminated wastewater treatment.

Wetlands constitute critical habitats sustaining cyanobacterial diversity. Nevertheless, taxonomic research on wetland benthic filamentous cyanobacteria is far from complete, largely limited by phenotypic plasticity and challenges in strain isolation and cultivation. To unravel the species diversity and taxonomic affiliations of epiphytic cyanobacteria in an urban wetland, cyanobacterial strains were isolated from riparian rocks of the Sanyang Wetland (Zhejiang Province) and characterized via morphological observation, 16S rRNA phylogenetic analysis and 16S–23S ITS structural comparison. Strain WZU 2025, sheathless with occasionally conical apical cells, fell into the genus Kamptonema. It shared less than 97.5% sequence similarity with K. animale and possessed distinctive ITS signatures, hereby proposed as Kamptonema schistus sp. nov. Strain WZU 2023, featuring colorless rigid sheaths and conical apical cells, formed a stable clade with Microcoleus but exhibited distinct ITS structures, and is designated Microcoleus wenzhouensis sp. nov. Strain WZU 2030 bears colourless rigid sheaths and trichomes mostly filled with chromatophores; it clustered reliably with known Wilmottia species yet differed in ITS traits, and is described as Wilmottia sanyangensis sp. nov. Conflicts between morphological taxonomy and molecular phylogeny reveal ambiguous intergeneric relationships within Coleofasciculaceae and Microcoleaceae. The present study expands the known diversity of Microcoleaceae and provides evidence for future taxonomic revisions of cyanobacteria. Combined with the new genus Paludothrix reported from this wetland in 2024, our data demonstrate that cyanobacterial diversity in Sanyang Wetland has been severely underappreciated.

Cyanobacteria-derived microcystins (MC) are widespread hepatotoxins threatening water security, with known producers primarily limited to specific genera. To expand the diversity of MC-producing cyanobacteria, we conducted an environmental DNA (eDNA)-based survey of cyanobacterial communities across the Lake Qinghai Basin (Qinghai-Tibet Plateau), a unique high-altitude brackish aquatic system, and isolated six coccoid cyanobacterial strains from Lake Yueya, a shallow sub-lake of Lake Qinghai. These six strains were characterized via a polyphasic approach, and morphological examinations (light and transmission electron microscopy) revealed key diagnostic features of Snowella (Chroococcales, Cyanobacteria), including spherical colonies with radial cell arrangements and central stalks. Further, molecular analyses confirmed their affiliation with Snowella via 16S rRNA gene and 16S-23S ITS phylogeny, and the MC synthesis gene mcyE was successfully detected. UPLC-MS/MS further identified MC variants (MC-LR, MC-RR, MC-YR) in selected strains, and strain CHAB 6606 was detected to have intracellular MC-LR (82.4 fg·cell⁻¹) and MC-YR (247.0 fg·cell⁻¹), higher than the typical Microcystis strains. Notably, our deposited mcyE sequences in Genbank are the sole basis for identifying the three global locations with potential MC-producing Snowella populations. This study provides the first formal confirmation that Snowella produces MC, expanding the diversity of MC-producing cyanobacteria to high-altitude brackish habitats. Our findings establish a molecular framework for global Snowella-associated MC risk surveillance, supporting targeted aquatic toxin monitoring and advance understanding of the taxonomic spectrum of MC-producing cyanobacteria worldwide.

Global warming intensification and anthropogenic activities have shortened the freeze-thaw period of rivers in cold regions. Benthic diatoms, essential components of river ecosystems, serve as both primary producers and reliable water quality indicators. However, existing studies on diatom communities have predominantly examined conventional environments, with limited investigation into their variations across distinct hydrological phases (freezing, thawing, and normal periods). In current study, Asymmetric Eigenvector Map analysis (AEM), Moran's Eigenvector Map analysis (MEM), and the principal coordinate of the neighborhood matrix (PCNM) were performed to explore the diatom community assembly in a seasonal freezing river. The AVD index was the lowest during the normal period, indicating greater stability of community, while the Niche width index reached its minimum during the freezing period. Additionally, environmental filtering played a dominant role in community assembly during three hydrological periods. Among these three dispersal processes, AEM exerted the greatest influence on diatom community assembly. Conversely, dispersal processes played a less substantial role in small-scale rivers. This study provides critical insights into the role of dispersal processes in the community assembly of benthic diatoms in rivers under different hydrological conditions. Additionally, combining dispersal processes with the WQI (Water Quality Index) yields a novel water quality indicator, providing an effective method for water quality assessment. Meanwhile, benthic diatoms retained their indicative significance in freeze-thaw rivers, serving as valuable indicators of environmental change. These findings have important implications for river ecosystem water quality management in cold river basins.

The application of microalgae for industrial CO2 capture is often constrained by limited performance under elevated CO2. In this study, a high-CO2-adapted Euglena gracilis mutant (LE-VB) was obtained through microwave mutagenesis followed by stepwise CO2 acclimation (5-10%). Its physiological and molecular responses were evaluated to be under 5% and 10% CO2. Under the same CO2 condition (5%), LE-VB showed higher growth, biomass, carbon fixation, and paramylon accumulation than the wild type. These advantages were further enhanced by 10% CO2. LE-VB also exhibited higher chlorophyll and carotenoid contents under both conditions, indicating improved light harvesting and stress tolerance. Although no significant changes were observed in key photosynthetic genes (PsbO, rbcL), transcriptomic analysis revealed coordinated regulation of genes involved in photosynthetic electron transport, suggesting improved functional efficiency. Carbon assimilation showed CO2dependent adjustment. Under 5% CO2, elevated PEPC and PEPCK activities indicated greater involvement of auxiliary pathways, whereas under 10% CO2, increased Rubisco activity and reduced PEPCK expression suggested a shift toward direct Calvin cycle-driven fixation. LE-VB also showed efficient oxidative stress regulation, supporting stable performance under elevated CO2. These results highlight a practical non-GMO strategy for improving microalgal performance in CO2-rich environments.

Low temperatures suppress microbial growth and metabolism activity and pollutant removal in wastewater treatment systems. This study systematically compared shaping effect of micro electric fields (MEF) and pulsed electric fields (PEF) on municipal wastewater treatment by a microalgae-bacteria system (MBS) at 5 °C, 10 °C, and 15 °C. Both electric field modes showed significant improvement in cell biomass accumulation, photosynthetic pigment synthesis, and nutrient and COD removals compared to non-electrified controls. Under identical operating conditions, MEF and PEF exhibited distinct electrobiological modulation behaviors, MEF promoted more stable cell biomass-pollutant coupling under cold stress, whereas PEF provided stronger short-term stimulation at moderately low temperatures. Energy analysis showed that PEF reduced volumetric energy consumption by 20-50% compared with MEF. Overall, a coupled process of microalgal-bacterial consortia and PEF offers an energy-efficient, non-thermal complementary strategy to conventional thermal approaches for wastewater management under low-temperature conditions.

Phytoplankton communities typically comprise a few dominant species and numerous rare ones, but their responses to seasonal precipitation changes remain poorly understood. To address this knowledge gap, investigations were conducted on the environmental conditions and phytoplankton communities in the Lalin River Basin during the dry and rainy seasons. Structural equation modeling and co-occurrence network analysis were then utilized to explore the assembly processes of dominant and rare phytoplankton communities following a seasonal heavy rainfall event. Our results showed seasonal heavy rainfall events significantly altered the phytoplankton community composition and rare phytoplankton diversity (p < 0.05). Furthermore, the stochastic process was particularly pronounced for rare species (i.e., 4.44%, p < 0.01). Co-occurrence network analysis revealed that increasing precipitation enhances the complexity and stability of phytoplankton ecological networks. Additionally, the relative importance of dominant species decreases, while that of rare species increases. This phenomenon can be described as the seasonal heavy precipitation weakening the so-called “Matthew effect” in the ecosystem. In summary, our results shed light on the phytoplankton ecology of agricultural rivers and reveal how changes in precipitation influence the formation of phytoplankton sub-communities and the structure of their networks.

Euglena gracilis is promising for CO2 bioutilization, but its metabolic response to elevated CO2 is poorly characterized. Here, the LE-ZW mutant, obtained via UV mutagenesis and CO2 acclimation, was evaluated under 5% and 10% CO2. LE-ZW exhibited 7% higher cell density and a 61% increase in photosynthetic carbon fixation at 10% CO2 compared with 5% CO2. Carbon allocation shifted with CO2 concentration: lipid accumulation peaked at 20.57% under 5% CO2, while paramylon content reached 37.37% under 10% CO2. Protein levels increased by 4% under high CO2 (vs 5% CO2 in LE-ZW). Transcriptomic and metabolomic analyses revealed extensive metabolic reprogramming: vs the wild type at 5% CO2, LE-ZW had 923 upregulated genes and 243 increased metabolites (enriched in TCA cycle and fatty acid biosynthesis, including 1.38-fold higher eicosapentaenoic acid); vs 5% CO2 at 10%, it had 396 upregulated genes and 20 increased metabolites (enriched in Calvin cycle, GS-GOGAT pathway, and aminoacyl-tRNA biosynthesis). These changes identified regulatory hubs (glycolysis-gluconeogenesis nodes, acetyl-CoA supply, glucose-6-phosphate partitioning) that redirected carbon flux between lipids and paramylon. Antioxidant defense was enhanced (29% higher superoxide dismutase activity). These results demonstrate LE-ZW's integrated regulation of carbon-nitrogen metabolism and redox homeostasis under high CO2, supporting its potential for industrial CO2 mitigation and bio-based production.

A new genus and species of freshwater diatoms from the Guangxi Autonomous region of southern China were studied with light and scanning electron microscopy. The newly proposed genus has several features that assign it to the Naviculaceae, including symmetry about the apical, transapical and pervalvar axis, slit-like areolae that are occluded internally by fine hymenes, hook-like external distal raphe ends and the presence of an internal auxillary rib bordering the raphe sternum. These features also suggest a strong morphological similarity with the genus Navicula. The new genus and species, however, have several external flaps of silica on the valve face and apex that give the raphe a bifurcate appearance, a feature not found in any Navicula species and more reminiscent of the genus Neidium. Also present is a hooded structure on the auxillary rib that covers the central nodule and expanded central area on both sides of the raphe, on one side resembling a forked expanded fascia. These features of the exterior and interior of the valve are not seen in other Navicula species, or in other genera within the family. The proposed new genus and species, Trialacinia guangxiana joins other diatom genera and species being endemic from the Guangxi Autonomous region of China.

The diatom Phaeodactylum tricornutum is known for its rapid growth and high fucoxanthin content (1-3% of dry weight), a photosynthetic pigment with considerable pharmaceutical and nutraceutical potential. Despite these advantages, the commercial biotechnological applications of this organism have not yet been realized, primarily due to challenges in scaling up photobioreactor (PBR) systems, as well as issues with the organism's robustness and production processes. In this study, we present a multifaceted approach to enhance fucoxanthin productivity by combining innovations in PBR design, strain improvement, and LED light recipes. Systematic evaluation of P. tricornutum in 700 mL column PBRs identified optimal light conditions (e.g., 660 nm red light at 50 mu mol photons m-2 s-1 with optimized light regimes), which were subsequently scaled up to novel 200 L and 10,000 L PBRs. Meanwhile, atmospheric and room temperature plasma mutagenesis, coupled with an adaptive evolution screening technique, generated superior mutant consortia exhibiting enhanced phenotypic characteristics, including higher fucoxanthin yield and long-term stability of cultivation. Comparative cultivation experiments in the 10,000 L PBR demonstrated the superiority of the mutant consortia, yielding 0.59 g L-1 biomass (an 18% increase) and 7.29 mg L-1 fucoxanthin (a 32.79% increase) compared to the wild type strain. Productivity was significantly improved, with biomass and fucoxanthin production rates reaching 0.12 g L-1 d-1 (a 33.33% increase) and 1.47 mg L-1 d-1 (a 54.74% increase) in the 10,000 L PBR, respectively. This work provides an optimized light recipe, superior mutant consortia, and scalable PBR design, effectively bridging laboratory-scale research with industrial application potential.

This study investigates the acute toxicity effects and apoptosis mechanisms of perfluorooctanoic acid (PFOA) on Nitzschia palea (N. palea), aiming to provide a theoretical foundation for the joint risk assessment of perfluorinated compounds (PFCs) in aquatic ecosystems. N. palea was exposed to PFOA concentrations ranging from 0 to 320 mg center dot L- 1, and the effects of exposure on cell density, Chl a, antioxidant systems, and cell morphology were analyzed. The results showed that the 96-h EC50 of PFOA-induced N. palea was 90 mg center dot L-1. PFOA concentrations of <= 40 mg center dot L- 1 promoted algal reproduction, while higher doses inhibited growth. Optical and scanning electron microscopy revealed that some N. palea cells had distinctly raised or depressed shell edges. The increase in reactive oxygen species (ROS) and antioxidant substances (SOD, CAT, and GSH) indicated that PFOA induced oxidative stress. Based on flow cytometry and AO/EB morphological observations, PFOA was found to induce apoptosis in N. palea cells. Transcriptomic analysis and qRT-PCR results showed that PFOA promotes the expression of mitochondria-associated apoptosis-related genes (NpCyt C, NpCaspase-3, and NpCaspase-9) in N. palea. This indicates that PFOA enhances the production of ROS in N. palea. Moreover, it initiates the mitochondrial apoptosis pathway by upregulating the expression of NpCyt C.

During the investigation of freshwater biodiversity of Xizang Autonomous Region, diatom samples were collected from several habitats and two new species were discovered and are formally described herein, namely, Gomphosinica stoermeri Liu, Kociolek et Li sp. nov., and Gomphosinica qii Liu, Kociolek et Li sp. nov. Both of these new species have biseriate striae, straight raphe ends, pseudosepta at both ends and a hooded stigma covering in the central area. Gomphosinica stoermeri can be separated from other similar species by its clavate outline, bluntly rounded headpole, rounded footpole, small and rounded central area formed by 2-4 short striae. Gomphosinica qii is relatively small, has small and more elliptical valves, small bluntly headpole and narrow footpole, round to rhombic central area formed by 2-6 short striae. Specimens which appear very similar to Gomphosinica hedinii were observed, but the outline and shape of central area do not match the original of Gomphosinica hedinii; herein we document these specimens and designate them as "Gomphosinica cf. hedinii". Gomphosinica linearis was also observed, and we provide a more detailed description of it based on LM and SEM. Differences between the two newly described species and other known species of the genus are also discussed.

The loss of biodiversity in urban wetlands has become increasingly severe due to urbanization. Based on their attachment patterns, benthic diatoms can be divided into several types according to habitat (i.e., epilithic, epiphytic, and epipelic). Diatoms are often used as ecological indicators due to their sensitivity to environmental changes. However, details concerning the composition, temporal dynamics, and assembly mechanisms of benthic diatom communities in urban wetland habitats remain unclear. In this study, we systematically evaluated the composition and seasonal dynamics of benthic diatoms among three different habitats and validated the applicability of eDNA for studies of diatoms. The relationship between the taxonomic and functional diversity of diatom communities was examined, and the assembly mechanisms of diatom communities were explored. An analysis of 249 benthic diatom samples and 27 water samples from nine sites over eight months revealed differences in the composition of diatom communities among epilithic, epiphytic, and epipelic habitats. In diatoms from different hydrological periods, the contribution of turnover to total taxonomic beta diversity was much larger than that of nestedness, while the nestedness components of functional diversity were comparatively large. Nutrients, total dissolved solids, and water temperature were the main variables that affected the taxonomic and functional beta diversity of the benthic diatom communities. The results suggested that benthic diatom community assembly in the three habitats and eDNA was primarily driven by deterministic processes. This study has demonstrated how habitat preference affects the composition, beta diversity and assembly processes of benthic diatom communities and provided novel insights into the conservation of biodiversity in urban wetlands.

Delicata is a genus of globally distributed, freshwater cymbelloid diatoms. We analysed the variability of valve morphology across species of the genus from China, New Caledonia, Central Europe and southwest Russia. The analysis focused on key distinctive features of Delicata: the arrangement and structure of striae, morphology of apical areolae and presence or absence of stigmata. As a result, we have re-evaluated the importance of ultrastructural valve characters for taxonomy and phylogeny of Delicata and proposed a new term 'apical stria cluster' to name the apical areolae in certain species of Delicata. We also discussed the structure of isolated pores - parastigmata - in the genus. In addition, a new species of genus, Delicata zhangii sp. nov. was discovered in Shaanxi and Hubei provinces, China. The new species is hereby described on the basis of unique combination of valve features - lunar-lanceolate outlines with barely protracted apices, linear striation, presence, structure of stigmata and areolae. Comparisons are made amongst the species of the genus within the framework of the morphological analysis.

Deterministic and stochastic processes are important to the formation of biological communities in community assembly mechanisms. However, the mechanisms of community assembly of phytoplankton and benthic diatoms are still poorly understood in different periods and regions in urban wetlands. In this study, we collected phytoplankton and benthic diatom samples from eight urban wetlands in cold regions from April 2023 to March 2024. We then examined distance–decay relationships (DDRs) patterns across three regions (the Northern Songhua River, Songhua River and Southern Songhua River) and four periods (dry, wet, freezing and frozen seasons). We observed significant DDRs curves in the phytoplankton community among different periods and regions, with the DDRs slopes being found in the Songhua River. Furthermore, variation partition analysis and structural equation modeling revealed that spatial and environmental factors had different effects on phytoplankton and benthic diatom communities. These findings suggest that phytoplankton communities were driven by stochastic process, while the deterministic process was a slightly stronger influencing factor in the assembly of benthic diatom communities. Together, the results of this study provide a scientific basis for the management and protection of water ecosystems in cold regions and help explain microbial diversity in urban wetlands.

Chagan Lake is the largest meadow-type lake in Northeast China. Over the past century, due to anthropogenic disturbances and regional environmental changes, its aquatic ecosystem has suffered significant stress. This study used sediment diatom records, 210Pb dating, and ecological classification indices to reconstruct the historical water environment changes of Chagan Lake from the mid-19th century to the mid-20th century. Two distinct ecological phases were identified: (1) Zone I (ca. 1859–1950 CE) recorded stable, weak alkaline (pH classes 3–4) and fresh-brackish (salinity class around 2) conditions, with diatoms Aulacoseira granulata (43–72%) and Aulacoseira ambigua (4–17%) being dominant, indicating a moderately eutrophic state with a relatively low level of organic pollution. (2) Zone II (ca. 1951–1962 CE) marked a transition to fluctuating conditions, with a sharp decline in A. granulata (16–36%) and an increase in pollution-tolerant taxa (such as Stephanocyclus meneghinianus: 2–32%, Nitzschia palea: 7–20%), and changes in oxygen requirements (classes 2–3 to 2–4), saprobity (classes 1–2 to 2–3), nitrogen metabolism (classes 1–2 to 1–3), and trophic state (classes 4–5 to 5). Hierarchical clustering and principal component analysis confirmed that significant changes occurred in the diatom community around the 1950s, associated with population growth, increased agricultural runoff, and altered hydrological conditions. Although pH values and salinity thresholds remained stable, the nutrient status developed towards eutrophication after the 1950s. Sedimentological data further indicated accelerated sedimentation rates (0.34 cm·yr−1 pre-1950s vs. 1.31 cm·yr−1 post-1980s) and notable changes in grain-size characteristics, attributable to combined anthropogenic erosion, hydrological engineering, and climatic influences. These findings established a baseline for understanding the anthropogenic impacts on Chagan Lake over a century scale and emphasized the urgency of adopting targeted restoration strategies for shallow, semi-arid lake ecosystems facing similar stressors.

Appropriate concentration of carbon dioxide (CO2) will promote algae growth and metabolism. Building upon this finding, the present study investigated the impact of different CO2 concentrations (5% and 20%) on the carbon sequestration capacity of E. gracilis through aeration culturing, employing a combination of physiological analyses and transcriptome analysis. The results demonstrated that under 5% CO2 concentration, the cell density of E. gracilis was 1.79 times higher than that achieved in an air culture condition, and the paramylon content of E. gracilis was found to be 6.18 times higher than that of the air group. Based on transcriptome analysis, the carbon metabolism of E. gracilis was discussed. Significant up-regulation expression of genes associated with carbon synthesis was validated by an increase in paramylon content. This study revealed that under 5% CO2 conditions, E. gracilis exhibited elevated growth rate and enhanced photosynthetic carbon assimilation efficiency.

This paper proposes a novel approach to optimize the plant recognition function of intelligent agricultural irrigation system, utilizing Stable Diffusion model and Lora (Low-Rank Adaptation) model. Stable Diffusion model is a latent diffusion model that converts text into images, while Lora is a method of fine-tuning large models by reducing trainable parameters while maintaining model performance as much as possible. By combining the Stable Diffusion model and Lora model, this paper trains custom models for each plant species using a small amount of data and generates corresponding images of each variety to assist training, thus optimizing classification results. In addition, to address the issue of imbalanced data, this study also introduces Focal Loss to mitigate the impact of both class imbalance and difficulty in classification. Building upon Focal Loss, CFloss is created as the model's loss function. This method was tested on the OxfordFlower102 dataset used by the original model, and the results demonstrate that it effectively improves classification accuracy and significantly enhances the plant recognition function of the irrigation system.