In order to explore a more efficient method for removing green algae from Neopropia yezoensis rafts in aquaculture, we modified an acid treatment vessel by loading a kind of mixed acid to remove Ulva species attached to N. yezoensis aquaculture rafts.By analyzing the algae tissue damage, biomass changes, photosynthetic fluorescence characteristics and attached algae population changes, the removal effect of acid treatment device equipped with mixed acid solution on the removal of attached Ulva spp. on the N. yezoensis aquaculture rafts was evaluated.The results showed that using an acid treatment vessel loaded with a pH = 0.8 mixed acid solution to treat the entire row of N. yezoensis aquaculture rafts (taking 7 min and 30 s) can reduce the biomass of green algae on the rafts net curtain by more than 95%, and will not have any adverse effects on N. yezoensis. This study verified that the acid treatment vessel using a mixed acid solution can effectively remove attached green algae on N.yezoensis aquaculture rafts. The aim is to develop and improve the technology for removing attached green algae during the aquaculture cycle, and to maximize the recovery of the mixed acid solution through a spray system. This not only reduces the biomass of Ulva spp. into the Yellow Sea green tide, but also minimizes the adverse effects of chemical control on the environment.

Mudflats stand out as significant carbon sinks within coastal wetlands, broadly distributing along the salinity gradient of the estuary. The shifts in the microecological environment caused by alternating wetting and drying (AWD) are crucial drivers affecting the accumulation of microbial derived carbon (MDC). However, the varied salinity intensified by climate warming may introduce an unpredictable element, complicating the assessment of carbon sequestration potential in mudflats. To gain insight into the response of MDC to AWD and salinity, a laboratory simulation experiment was conducted using a customized tidal simulator. Mudflat soils collected in June 2023 were exposed to a semidiurnal wetting-drying cycle under three salinity gradients (5‰, 20‰, and 35‰). Soils were sampled at days 1, 30, and 100 to analyze physicochemical properties, microbial biomass (via PLFAs), and specific MDC fractions. The results revealed that MDC, including microbial biomass carbon (MBC), extracellular polymeric substances carbon (EPSC), and bacterial necromass carbon (BNC), appeared different accumulated models, in response of AWD and salinity. Specifically, to cope with the salt accumulation resulting from AWD, salt-tolerant microorganisms adopt the “high-salt-in” and “compatible solute” strategies to boost MBC accumulation while also secreting abundant EPS to safeguard their cells. Meanwhile, the high-salinity environment disrupted microbial cells and promoted BNC formation, yet, also inhibiting its further degradation by microorganisms. The following conclusions were drawn by comparing accumulated MDC content across three salinity environments. Firstly, a certain threshold of EC (specifically 4.10 in a laboratory setting) will inhibit the accumulation of MBC. Secondly, the lower-survival microbial biomass in higher salinity environment will be the limit factor weakening the accumulation rate of BNC. In summary, AWD favor the accumulation of MDC in mudflats, whereas increased salinity due to climate warming may weaken the contribution of MDC to SOC.

Green tides have become a recurring ecological problem in the Yellow Sea, yet early-stage processes governing algal biomass supply remain poorly understood. Here, two years of continuous field observations (2023-2024) were conducted in the Neopyropia yezoensis aquaculture area of the Subei Shoal, China, to examine the seasonal succession of epiphytic green algal communities and their natural detachment during spring. Epiphytic communities exhibited a clear and repeatable successional pattern, shifting from dominance by cold-tolerant taxa in early spring to increased prevalence of Ulva prolifera by April, a transition closely associated with rising water temperatures. Natural detachment occurred continuously throughout the cultivation period, rather than being confined to the harvest stage. Detached biomass increased in concert with attached biomass, indicating a stable and persistent coupling between biomass accumulation and natural detachment in late spring. Spatial extrapolation suggested that natural detachment reached approximately 327.14 t and 656.96 t (wet weight) in April 2023 and 2024, respectively. Although these amounts are smaller than peak floating biomass during summer green tides, their seasonal timing coincides with the initial phase of bloom formation and may contribute to the background supply of floating algal material. Together, these findings provide field-based evidence that aquaculture-associated epiphytic algae represent a sustained early-season source of algal input to coastal waters. Incorporating epiphytic algal dynamics into monitoring, early warning, and management frameworks may improve prediction and mitigation of green tide development in aquaculture-dominated coastal systems.

Ulva prolifera, the principal driver of green tides worldwide, can form massive blooms that severely disrupt coastal ecosystems and cause substantial economic losses. However, its global potential distribution and responses to future climate change remain poorly resolved. Here, we used a MaxEnt species distribution model to simulate the current and future (SSP5-8.5) global suitability patterns of U. prolifera, achieving high predictive performance (AUC = 0.982 ± 0.005). Our results indicate that three groups of environmental factors jointly constrain its potential range: minimum iron concentration acts as the fundamental limiting factor for basic growth; minimum primary productivity, maximum dissolved oxygen, and maximum chlorophyll regulate the development of high-biomass blooms; and minimum temperature sets the thermal boundary for high-latitude distribution and overwintering. Present high-suitability zones are markedly clustered along mid- to high-latitude continental shelves (Moran’s I = 0.727, p < 0.001). Under the SSP5-8.5 scenario, warming relaxes thermal limitations at higher latitudes and drives poleward expansion of suitable habitats, whereas cold-current regions remain unsuitable due to persistently low temperatures. In contrast, most open-ocean areas show limited change in suitability owing to sustained iron limitation and nutrient scarcity. These findings elucidate the dominant environmental controls and climate responses of U. prolifera suitability and provide a scientific basis for green-tide prevention and marine ecological risk assessment in a warming ocean.

Massive green tides have emerged as a severe global environmental issue. Citric acid-activated chlorine dioxide (ClO2) is a potential chemical control agent against the dominant causative macroalga, Ulva prolifera, but its molecular mechanism of action remains poorly understood. This study combined physiological assessments with transcriptome sequencing to characterize the responses of U. prolifera to citric acid-activated ClO2 exposure at 0, 50, 100, and 150 mg/L. Physiological results indicated that 100 mg/L ClO2 (G100) was the threshold for irreversible impairment of photosynthetic activity in U. prolifera, whereas 150 mg/L ClO2 (G150) was a stable lethal concentration. While the G50 exposure group maintained cellular homeostasis via a constrained compensatory response, exposure at G100 and G150 elicited extensive transcriptomic reprogramming. Notably, at G150, despite the collapse of photosynthetic functions, genes associated with photosynthesis, protein synthesis (ribosomes), mitochondrial respiration, and cellular stress-response pathways (HSPs, ROS scavenging enzymes, ABC transporters) were significantly upregulated. This massive transcriptional activation likely represented a high-cost compensatory strategy under severe oxidative damage. However, the immense energetic burden of maintaining high levels of transcripts associated with defense and repair likely disrupted cellular homeostasis, ultimately leading to physiological failure and cell death. This study provides the first transcriptomic characterization of the concentration-dependent molecular mechanisms underlying ClO2-induced lethality in a green macroalga. These findings deepen the understanding of its algicidal action and provide an important theoretical basis for optimizing chemical control technologies for green tides.

Parkinson's disease (PD) is closely associated with mitochondrial dysfunction and oxidative stress. Sargassum horneri polyphenols (SHPP), as a marine-derived natural active substance, have potential neuroprotective effects, but their efficacy and mechanisms in PD models remain unclear. In this study, SH-SY5Y cells were first differentiated with all-trans-retinoic acid (ATRA) and then treated with rotenone to establish an in vitro Parkinson's disease injury model. The protective effects of SHPP were systematically evaluated, and its mechanism of action was preliminarily explored using transcriptomics. Results showed that SHPP intervention dose-dependently ameliorated rotenone-induced cell injury: cell viability in the medium- and high-dose groups was restored to 71.6% and 73.3% of the control level, ATP content to 71.2% and 74.6%, and mitochondrial complex I activity to 67.5% and 71.3%, respectively. In the high-dose group, reactive oxygen species (ROS) level decreased to 81.2% of the model group level, malondialdehyde (MDA) decreased to 68.7% of the model group level, and superoxide dismutase (SOD) activity and reduced glutathione (GSH) content was restored to 83.7% and 82.8% of the control level, respectively. In terms of apoptosis regulation, SHPP down-regulated Bax, up-regulated Bcl-2, decreased the Bax/Bcl-2 ratio, and reduced cytoplasmic cytochrome c (by 14.3%) and Cleaved Caspase-3 (by 13.6%) levels. Meanwhile, SHPP reduced the secretion of pro-inflammatory factors TNF-α, IL-6, and IL-1β, and down-regulated BAX mRNA expression while up-regulating BCL2 , NFE2L2 , and HMOX1 mRNA expression. Transcriptomic analysis revealed that only 28 differentially expressed genes were identified after SHPP intervention, of which 8 were common differentially expressed genes between the model and treatment groups (including TMEM102 , MIR34AHG , etc.), indicating that SHPP does not function by broadly altering gene expression but rather acts precisely on core genes in the disease model. In conclusion, SHPP exerts neuroprotective effects against rotenone-induced SH-SY5Y cell injury by restoring mitochondrial function, alleviating oxidative stress, inhibiting mitochondria-mediated apoptosis, and reducing neuroinflammation, providing experimental evidence for the potential application of S. horneri polyphenols in the prevention and treatment of Parkinson's disease.

Ulva prolifera (U. prolifera), a fast-growing green macroalga, plays an important ecological role in coastal ecosystems by contributing to primary production, nutrient cycling, and carbon capture. However, under eutrophic conditions, it can proliferate into harmful green tides. Iron (Fe) is an essential micronutrient influencing its growth and bloom dynamics, acting as a concentration-dependent regulator whose effects vary with environmental conditions. This review examines how Fe availability influences the physiological and ecological performance of U. prolifera, with emphasis on experimentally supported responses and environmentally relevant Fe conditions. We present an evidence-based synthesis describing Fe uptake processes and environmentally mediated responses under both Fe deficiency and excess. Particular attention is given to experimentally documented responses such as growth variation, photosynthetic performance, nutrient assimilation, and stress-related physiological adjustments. Moderate concentrations of bioavailable Fe(II) (generally reported within low micromolar ranges in coastal environments) enhance photosynthetic activity, nitrogen assimilation, and biomass accumulation in Ulva sp. systems, as demonstrated in controlled cultivation and environmental studies. However, excessive Fe concentrations can disrupt physiological balance, impair photosynthetic processes, and suppress growth. The transition from beneficial to inhibitory effects depends on Fe speciation, exposure duration, and interactions with environmental drivers, including nitrogen availability, phosphorus levels, light intensity, salinity, and redox conditions. To ensure scientific accuracy, this review distinguishes clearly between species-specific observations in U. prolifera and comparative findings derived from closely related Ulva spp. Where direct studies on U. prolifera were limited, supporting evidence from related species such as U. pertusa, U. lactuca, and U. rigida was incorporated cautiously and explicitly identified as comparative information rather than direct species-specific evidence. This approach reflects the current state of knowledge, as relatively few studies have directly examined Fe-related physiological mechanisms in U. prolifera. By integrating available physiological and ecological observations across laboratory and field studies, this review provides a conservative and evidence-based framework for understanding Fe-dependent responses in Ulva sp. systems. This understanding has implications for predicting green tide dynamics under eutrophication and climate variability, improving nutrient management strategies in coastal aquaculture systems, and evaluating the potential role of macroalgae in nature-based environmental management. Furthermore, this review identifies key knowledge gaps, including the limited availability of species-specific Fe physiology data for U. prolifera, the need for improved understanding of Fe speciation effects under natural conditions, and the role of microbial interactions in regulating Fe bioavailability. Addressing these gaps will be essential for advancing predictive models of green tide formation and supporting sustainable coastal ecosystem management.

White Spot Syndrome Virus (WSSV) is a highly lethal pathogen threatening global shrimp aquaculture. The VP28 recombinant plasmid has a promising prospect for vaccine development, but it is limited by the choice of live vectors. Based on previous studies that used microalgae as gene expression live vectors, this research innovatively adopted probiotics (Lactobacillus acidophilus) as expression vectors and utilized green fluorescent protein (gfp) to visualize the colonization and gene expression process of probiotics in the intestinal tract in real time. We evaluated its effects on growth, intestinal colonization, gut microbiota modulation, and antiviral resistance in Litopenaeus vannamei. The recombinant strain (L. acidophilus pMG36e-vp28-gfp group) significantly promoted shrimp growth (final weight: 1.20 g vs. control 0.8 g) and stably colonized the intestine for up to 8 days, as visualized by GFP fluorescence. In WSSV challenge trials, the L. acidophilus pMG36e-vp28-gfp group achieved a survival rate of 66%, markedly higher than the positive control (8%), wild-type L. acidophilus (36%), and L. acidophilus pMG36e groups (empty-vector, 44%). 16S rRNA sequencing results showed that the recombinant strain reduced the relative abundance of the opportunistic pathogen Vibrio and increased microbial diversity, thereby alleviating WSSV-induced dysbiosis. Functional prediction analysis further revealed significant enrichment of immune-related and metabolic-related pathways. This enrichment may help reduce WSSV-Vibrio coinfection, and also suggests that gut microbiota immune priming might alleviate WSSV-induced metabolic disruption in the host.These findings demonstrate that recombinant L. acidophilus delivering VP28 antigen can remodel gut microbiota and enhance antiviral resistance, providing a novel probiotic-based immunoprophylactic strategy against WSSV.

Ulva prolifera (U. prolifera), a large green alga widely distributed along coastlines worldwide, can trigger marine ecological issues such as “green tides” when over-proliferating. Nevertheless, it is abundant in various nutrients and bioactive compounds, making the utilization of this alga an urgent task. In this study, an antioxidant peptide fraction (UCP‑1) was isolated and purified from U. prolifera. LC‑MS/MS analysis indicated that the peptide composition and molecular weight distribution of UCP‑1 possess typical characteristics of antioxidant peptides. In vitro experiments demonstrated that UCP‑1 at a concentration of 1 mg mL⁻¹ exhibited a DPPH radical scavenging capacity of 38.86 ± 2.7

The frequent occurrence of green tides in the Yellow Sea poses a significant threat to both coastal ecosystems and local economies. Traditional monitoring methods struggle to accurately assess the dynamics of Ulva prolifera micropropagules due to their delayed response, limiting early prevention and control efforts. For proactive observation of green tides to better understand their biological invasion, this study applied environmental DNA (eDNA) technology for the first time to investigate the attached of Ulva along the southern coast of the Shandong Peninsula. Surveys at 18 stations were carried out in November 2023 and March 2024. High-throughput sequencing and molecular identification were used to analyze the spatial and temporal distribution patterns of macroalgae micropropagules and the underlying ecological drivers. The results showed that, compared with autumn, the relative sequence abundance of Chlorophyta increased in spring, with a 180-fold increase in eDNA signal in Longwan, Langya Town, linked to the disappearance of attached macroalgae. This shift indicated a seasonal ecological niche shift of U. prolifera from “benthic anchorage” to “floating proliferation”, highlighting a potential outbreak risk area. Correlation network analysis showed that U. prolifera was positively correlated with other green macroalgae species and certain protists (e.g., Massisteria marina), suggesting its potential influence on community structure through changes in habitat conditions and food chain dynamics. This study confirms that eDNA technology can effectively capture the dynamics of micropropagules in real-time, providing valuable data for early warning of green tides.

Skin photoaging is primarily induced by ultraviolet (UV) radiation and is accompanied by extracellular matrix (ECM) degradation, abnormal pigmentation, and loss of skin elasticity. Excessive melanin synthesis represents a key cause of pigmentary skin disorders. Natural polyphenols with dual skin-whitening and anti-photoaging activities have attracted increasing attention as cosmetic ingredients. This study examined the effects of polyphenol-enriched fraction from the brown alga Sargassum fusiforme (SFP). Zebrafish embryos and human melanoma A375 cells were used to evaluate the depigmenting efficacy of SFP, while UVA-induced human dermal fibroblasts (HDFs) were employed to assess its anti-photoaging activity. SFP significantly decreased melanin levels in both models in a dose-dependent and reversible manner by suppressing tyrosinase activity. In terms of anti-photoaging effects, SFP markedly suppressed UVA-induced matrix metalloproteinases (MMPs) expression and elevated key ECM components, including type I collagen, elastin, and hyaluronic acid. In conclusion, SFP exerts dual beneficial effects by attenuating melanogenesis via tyrosinase inhibition and alleviating photoaging damage by suppressing MMPs to protect ECM. These results provide a scientific foundation for the use of SFP as a dual-purpose natural cosmetic ingredient with significant potential in the cosmetics sector.

Low temperature severely constrains the growth and ecological application of submerged macrophytes in aquatic ecosystem restoration. Although brassinolide (BR) has been shown to alleviate abiotic stress in terrestrial plants, its role in submerged macrophytes remains poorly understood. This study investigated the effects of different BR concentrations (0, 0.05, 0.1, and 0.5 mg L-1) on growth, photosynthesis, antioxidant defense, and osmotic adjustment in Hydrilla verticillata under low-temperature stress (2 °C) over 15 days. Exogenous BR significantly alleviated low-temperature-induced damage in H. verticillata in a concentration-dependent manner. Among all treatments, 0.05 mg L-1 BR showed the strongest overall effect, increasing fresh weight, dry weight, and plant height by 16.22%, 22.67%, and 9.52%, respectively, compared with the control. It also promoted photosynthetic performance, with Fv/Fm and Y(II) increasing by 251.93% and 262.83%, respectively, on day 10, and enhanced stress resistance, as reflected by a 32.44% increase in SOD activity and a 112.59% increase in soluble sugar content on day 15. In contrast, higher BR concentrations (0.1 and 0.5 mg L-1) were less effective overall. Membership function analysis ranked the treatments as 0.05 mg L-1 (0.95) > 0.1 mg L-1 (0.47) > 0.5 mg L-1 (0.19) > 0 mg L-1 (0.09). These results indicate that BR enhances low-temperature tolerance in H. verticillata through coordinated regulation of photosynthetic performance, antioxidant defense, and osmotic adjustment, providing a physiological basis for its application in submerged macrophyte restoration under low-temperature conditions.

Green tide events have broken out consecutively for years in the Southern Yellow Sea (SYS) of China. Unlike green tides in other countries and regions, those in the SYS show long-range dispersal, with research has primarily focused on the Neopyropia aquaculture area in the Subei Shoal. In this study, the biomass and species composition of attached green algae on the aquaculture ropes for Neopyropia yezoensis were observed across different elevation zones from March to April 2025. The results showed that, without affecting the yield of N. yezoensis, the biomass of attached green algae in the medium-elevation zone (which was exposed to air for about 4 h during the flood season) decreased significantly, and the proportion of Ulva prolifera among the attached green algae also dropped substantially. Specifically, the average biomass of green algae was highest in the low-elevation zone, while values in the medium- and high-elevation zones were relatively lower. This study investigates how different elevation zones (different drying times), affect green algae attached to Neopyropia aquaculture ropes, aiming to provide practical management strategies to mitigate biofouling during cultivation.

To investigate the molecular mechanisms of the aquatic plant Zostera caespitosa in response to temperature stress, this study analyzed its transcriptomic response characteristics under low and high temperature stresses. Through transcriptome sequencing of Z. caespitosa under 5 °C (low temperature) and 25 °C (high temperature) treatments, combined with GO functional annotation and enrichment analysis, KEGG pathway enrichment analysis, and WGCNA gene co-expression network analysis, we systematically dissected the functions of differentially expressed genes (DEGs) and their associations with phenotypic traits. The results showed significant differences in the response strategies of Z. caespitosa to low and high temperatures. At 5 °C, gene expression regulation focused on enhancing membrane stability (e.g., enriched in membrane components and linoleic acid metabolism) and protein processing, while suppressing energy-consuming processes such as ribosome biogenesis and photosynthesis. At 25 °C, the response features involved activation of brassinosteroid biosynthesis, hormone signal transduction, and other growth-related pathways, with photosynthesis-related genes also suppressed. WGCNA analysis further identified MEred and MEturquoise as two key co-expression modules, where the MEred module was significantly positively correlated with biomass and photosynthetic parameters and specifically upregulated under high temperature, revealing the important role of core gene networks in coordinating growth and stress responses. This study systematically revealed the complex transcriptomic regulatory network of Z. caespitosa in response to temperature stress, providing an important molecular basis for a deeper understanding of stress resistance mechanisms in aquatic plants.

Salinity severely limits global crop productivity, prompting a need to uncover plant salinity adaptation strategies. Suaeda salsa (L.) Pall., a halophyte thriving in saline habitats, offers a valuable model to dissect plant growth mechanisms under saline conditions. Although a chromosome-level reference genome of S. salsa was recently published, the corresponding gene annotation remained unavailable. Using the Helixer tool, we generated and released the first publicly available genome annotation for S. salsa, exhibiting high completeness with 92.80% (1,498) complete BUSCOs, thus providing an essential genomic resource. Using the S. salsa reference genome and annotation, we conducted RNA-seq-based transcriptomic profiling of plants subjected to 0, 200, and 400 mM NaCl for 30 days, respectively. We identified 462 significantly differentially expressed annotated genes across all treatments, with 11 key candidates consistently regulated. These genes are involved in key salinity response-related processes, including ion transport, osmotic adjustment, antioxidant defense, hormone signaling, transcriptional regulation, and genome plasticity. Enrichment analyses further supported their roles in ion homeostasis, redox regulation, and metabolic adjustment. This study provides new insights into the long-term salt tolerance mechanisms of S. salsa during normal development. The findings lay a foundation for future functional studies, comparative evolutionary analyses, and genetic improvement of salt-tolerant crops.

The green tide in the Yellow Sea, one of the largest globally, is primarily driven by the biomass of Ulva prolifera, which is influenced by seawater nutrient levels, particularly inorganic nitrogen and phosphorus. This study aimed to clarify the relationship between U. prolifera growth and seawater nitrogen and phosphorus concentrations. Experiments were conducted in the northern Jiangsu coastal waters using three nutrient concentration gradients (high, medium, and low) to assess their impact on U. prolifera biomass. Additionally, the proportional relationship between nutrient uptake by algal tissue and nutrient depletion from the water was analyzed. Results showed a significant positive correlation between nitrogen and phosphorus concentrations and U. prolifera growth, with Spearman's correlation coefficients exceeding 0.4 and p-values <0.05. Increased nitrogen and phosphorus levels promoted faster growth and higher biomass, with NH4+ having the most pronounced effect, leading to a maximum weight gain of 107.4 %. Nutrient uptake measurements indicated that for each gram of nitrogen absorbed, U. prolifera biomass increased by 277.9 g, and for each gram of phosphorus absorbed, biomass increased by 4056.5 g. In conclusion, nutrient enrichment accelerates U. prolifera growth, and limiting nitrogen and phosphorus inputs could reduce biomass accumulation in the early stages of green tide formation. These findings provide valuable insights for developing strategies to manage and control green tide events and protect marine ecosystems.

Introduction: Ulva prolifera, a dominant species in green tides, exhibits remarkable nitrogen absorption capacity, yet its kinetics as a biofilter in recirculating aquaculture systems (RAS) remain unquantified. Methods: This study systematically characterized NH4+-N, NO3--N, and NO2--N uptake kinetics in nitrogen-starved (7-day). U. prolifera across eight concentration gradients (NH4+-N: 0.5-35 mu molL-1; NO3--N: 5-130 mu molL-1; NO2--N: 2.5-60 mu molL-1). Result: Michaelis-Menten modeling revealed: NO3--N achieved the highest maximum uptake rate (V-max = 161.29 mu molg(-1)h(-1)), but the greatest half-saturation constant (K-m = 29.40 mu molL-1); NH4+-N showed the strongest affinity (K-m = 4.60 mu molL-1); NO2--N absorption plummeted at >50 mu molL-1 (41% removal after 6h). When the initial concentrations were below 20 mu molL-1 for NH4+-N, or below 90 mu molL-1 NO3--N, or below 20 mu molL-1 for NO2--N, 1 g of Ulva prolifera in 1 L of seawater completely achieving 100% removal efficiency for each within 6 hours. Critical inhibition thresholds were identified: NH4+-N >20 mu molL-1 reduced removal by 40-60%, NO3--N >110 mu molL-1 induced suppression, and NO2--N >30 mu molL-1 triggered acute inhibition. Conclusion: We propose optimized RAS protocols: maintain NH4+-N <= 20 mu molL-1 and NO2--N <= 30 mu molL-1, with 1.5-2x increased algal biomass when high total inorganic nitrogen concentration to sustain >90% nitrogen removal. This work demonstrates U. prolifera's nitrogen assimilation strategy-"high ammonium affinity, high nitrate capacity, nitrite sensitivity"-providing a mechanistic foundation for valorizing green-tide macroalgae in sustainable aquaculture.

This study systematically investigated two ecotypes of Ulva prolifera, the dominant species responsible for green tides in the Yellow Sea, classified as Subtype I (strain I08-1) and Subtype II (strain QD-7). Both subtypes produce positively phototactic biflagellate gametes with oval/pear-shaped morphology but exhibit distinct cellular dimensions. Subtype I gametes demonstrated significantly larger cell sizes, with long and short axes measuring 6.55 μm and 4.62 μm, respectively, compared to Subtype II’s dimensions of 6.46 μm (long axis) and 3.03 μm (short axis). Developmental analysis revealed striking morphological divergence at the 6-day germling stage: Subtype I attained an average length of 1301.14 μm, more than doubling Subtype II’s 562.25 μm. Superior growth kinetics were observed in Subtype I, exhibiting enhanced specific growth rates (SGRs) across multiple parameters—main stem length (8.58% vs. 3.55%), primary branch elongation (19.17% vs. 12.59%), main stem width expansion (17.29% vs. 5.00%), and biomass accumulation (41.90% vs. 40.96% fresh weight). Chlorophyll quantification confirmed significantly higher pigment content in Subtype I. Pre-co-culture photosynthetic profiling demonstrated Subtype I’s superior quantum efficiency (α = 0.077 vs. 0.045) with marked differences in regulated energy dissipation (YNPQ) and non-photochemical quenching (NPQ). Post-co-culture physiological adaptation was evident in Subtype II, showing significant elevation of non-regulated energy dissipation quantum yield (YNO) and eventual surpassing of maximum electron transport rate (ETRmax) compared to Subtype I. These findings establish that U. prolifera employs robust photoprotective and thermal adaptation strategies under natural photothermal conditions. Crucially, YNO-based analysis revealed Subtype II’s enhanced high-light protection mechanisms and superior adaptability to intense irradiance environments. This research elucidates ecotype-specific environmental adaptation mechanisms in U. prolifera, providing critical insights for optimizing green tide mitigation strategies and advancing ecological understanding of algal bloom dynamics.

Allelochemicals are recognized as promising algaecides due to their environmental safety. Para-tert-butylcatechol (TBC) and L-lysine exhibit significant potential in suppressing harmful algal blooms (HABs); however, their combined effects and algae inhibition mechanisms remain unelucidated. Therefore, this study systematically investigated the growth inhibition of Microcystis aeruginosa by TBC and L-lysine individually and in combination, while simultaneously examining their combined effects on algal growth, cell membrane integrity, photosynthetic activity, antioxidant responses, and microcystin production. The results revealed a significant interactive effect between TBC (0.04 mg/L) and L-lysine (1 mg/L), achieving over 90% growth inhibition within 96 h. The combined treatment significantly inhibited M. aeruginosa growth through impaired photosynthetic efficiency and elevated oxidative stress. Compared to the control group, the treatment group exhibited a continuous decline in chlorophyll-a content, phycobiliprotein levels, Fv/Fm, YII, α, and rETRmax, while phosphoenolpyruvate carboxylase (PEPC) activity decreased by 96.48% by day 8. And antioxidant enzymes, including superoxide dismutase (SOD) and reduced glutathione (GSH), showed a progressive increase in activity. In addition, the structure and integrity of the cell membrane of M. aeruginosa were damaged after treatment, and the conductivity of the treatment groups increased continuously from 2.32 to 4.63 μs/cm. In addition, under combined treatment, intra- and extracellular microcystin levels initially increased (peaking at day 2) but sharply declined thereafter, becoming significantly lower than controls by day 8. These findings highlight the potential of combining TBC and L-lysine as an eco-friendly and cost-effective strategy for mitigating M. aeruginosa-dominated harmful algal blooms.

The concept of sustainable development requires humanity to change their perception of the singular value of nature, enabling people to recognize the value of the natural world as a pathway to understanding. Currently, a key focus of research is how to promote rural sustainable development by realizing the value of ecological products. The pastoral complex is a significant carrier for realizing the value of ecological products, and the assessment and accounting of its ecological product value serve as essential foundations for realizing such value. However, existing research on the evaluation and accounting of ecological product value is mostly conducted on a larger scale, such as administrative divisions or natural ecosystems, with relatively fewer studies on small-scale economic entities. Therefore, this study intends to select the pastoral complex, a typical economic entity, as the research object, make clear the value types of ecological products of the pastoral complex through theoretical analysis and field research, and use the Delphi method and AHP to build an ecological product value evaluation system to carry out ecological product value accounting for the pastoral complex. The results showed that the Taihe Water Pastoral complex scored 7.045 points and was rated as excellent, while the Yinmin Fruit and Vegetable Pastoral complex only scored 4.579 points and was rated as excellent. Good ecological environment and high-quality ecological products have positive effects on the value evaluation of ecological products. The evaluation system constructed in this study can effectively reflect the ecological product value of pastoral complexes, and through in-depth comparison, present specific pathways for realizing this value. This provides a scientific reference for the sustainable development of rural areas, supports rural revitalization, and promotes equitable rural prosperity.