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Crude oil spills imperil aquatic ecosystems globally, prompting innovative solutions such as microalgae-based bioremediation. This study explores the potential of Chlorella vulgaris and Scenedesmus quadricauda, for crude oil spill phycoremediation under mixotrophic conditions and varying crude oil concentrations (0.5–2%). C. vulgaris demonstrated notable resilience, thriving up to 1% crude oil exposure, while S. quadricauda adapted to lower concentrations. Optimal growth for both was observed at 0.5% exposure. Chlorophyll a content in C. vulgaris increases at 0.5% exposure but declines above 1%, while a decline was noticeable in chlorophyll b in treatment groups above 1%. Carotenoid levels varied, displaying the highest levels at higher concentrations above 1.5%. Similarly, S. quadricauda showed increased chlorophyll a content at 0.5% exposure, with stable carotenoid levels and a decline in chlorophyll b content at higher concentrations. GC/MS analyses indicated C. vulgaris efficiently degraded aliphatic compounds like decane and tridecane, surpassing S. quadricauda in degrading both aliphatic and aromatic hydrocarbons. Growth kinetics was best represented by the modified Gompertz and logistic models. These findings highlight the species-specific adaptability and optimal concentration for microalgae to degrade crude oil effectively, advancing phycoremediation processes and strategies critical for environmental restoration. NOVELTY STATEMENT: This study marks the first exploration of both Chlorella vulgaris and the previously unexplored Scenedesmus quadricauda for crude oil phycoremediation potential under mixotrophic conditions. Additionally, it pioneers the modeling and study of algae growth kinetics in response to crude oil exposure. Notably, this research demonstrated the adaptability and efficiency of C. vulgaris in degrading crude oil components under mixotrophic conditions up to a level of 1%, while S. quadricauda showed similar capabilities at a concentration of 0.5%. [ABSTRACT FROM AUTHOR]

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Extreme wildfire events and cyclones are on the rise across tropical regions in response to climate change. Despite assumptions about their impact on phytoplankton through nutrient supplies, field evidence is lacking, and their combined effects remain unclear. In an on‐site microcosm experiment conducted in the Xisha Islands, South China Sea (SCS) after Typhoon Noru, we observed enhanced phytoplankton growth in response to exposure to total suspended particulates (TSP) from wildfires (2 mg/L and 6 mg/L) under wind‐driven upwelling conditions. Upwelled nutrients had a limited effect on Chl‐a concentration due to phosphate depletion, by contrast, wildfire TSP contributed nutrients enriched in nitrogen and phosphate, resulting in a 3.30–5.61‐fold increase in Chl‐a. However, upwelled nutrients increased the diatom‐to‐dinoflagellate ratio from the initial 11.0 to 12.7, TSP at low and high levels reduced the ratio to 0.3–0.8 and significantly altered the communities, with 61.8% of species, including two dominant diatoms, negatively correlated with N and/or P supplies. Species diversity declined significantly at high TSP levels. These findings suggest that enhanced primary productivity by wildfires may come at the cost of an altered phytoplankton community. This field study improves understanding of the effects of simultaneous occurrences of multiple extreme climate events on marine ecosystems. Plain Language Summary: Increasing wildfires and typhoons in tropical regions due to global warming are believed to affect algae growth by altering nutrient inputs from atmospheric deposition and upwelling. Tropical coral reefs rely on algae to sustain high biomass in the food web. However, there is limited evidence of how wildfires impact algae under upwelling conditions. This study in the coral reef regions of the SCS found that wildfires provide nutrients including nitrogen and phosphorus, which enhance algae growth more effectively under upwelling compared to upwelling alone. However, when typhoon and wildfire particles are combined, they tend to alter the types of algae present. Some algae become less competitive, leading to reduced species diversity overall. Given the potential variations in carbon export efficiency among species, wildfires may influence carbon sequestration by algae. This field study suggests that the simultaneous occurrence of wildfires and tropical cyclones may enhance productivity but pose potential risks to coral reef ecosystems. Key Points: Wildfire particulates (2–6 mg/L) alleviated P limitation and extended the promotion of phytoplankton growth under wind‐driven upwellingWhen combined with upwelling, wildfire particulates altered the phytoplankton community, lowering the diatom‐to‐dinoflagellate ratioNearly 60% of algal species displayed a negative relationship with N and/or P provided by wildfire particulates [ABSTRACT FROM AUTHOR]

This study investigated the effect of co-culturing the photobiont and mycobiont in the microbial fuel cell (MFC) cathode on biomass production, lipid generation, and power output. Chlorella vulgaris provides oxygen and nutrients for the yeast Cystobasidium oligophagum JRC1, while the latter offers CO2 and quench oxygen for higher algal growth. The MFC with co-culture enhanced the lipid output of biomass by 28.33%, and the total yield and productivity were 1.47 ± 0.18 g/l and 0.123 g/l/day, respectively. Moreover, with co-culture, the open circuit voltage of 685 ± 11 mV was two times higher than algae alone. The specific growth rate (day−1) at the cathode was 0.367 ± 0.04 in co-culture and 0.288 ± 0.05 with C. vulgaris only. The power density of the system was 5.37 ± 0.21 mW/m2 with 75.88 ± 1.89% of COD removal. The co-culture thus proved beneficial at the MFC cathode in terms of total energy output as 11.5 ± 0.035 kWh/m3, which was 1.4-fold higher than algae alone. [ABSTRACT FROM AUTHOR]

Microalgae paves the way towards a negative emission technology; however, single-pot systems combining nutrient removal and wastewater treatment are scarce in the literature. In this study, three different types of wastewater (university, municipality, and dairy industries) were studied using microalgae towards treatment and nutrient removal using Scenedesmus sp. and Chlorella sp. The experiments were carried out in 20 L reactors, for 9 days, where in achieving a maximum of algal growth rate of 770 and 725 mg/L for Scenedesmus sp. and Chlorella sp., respectively. Of the three wastewaters, dairy wastewater had the highest influent COD (3488 mg/L), which was reduced by 92% after 9 days. The pigment content was highest after 6 days (0.22 ± 0.03%), and there was no significant improvement after 9 days, suggesting a trade-off between nutrient removal, photosynthetic performance, and COD reduction. Microalgae act as a sustainable solution and negative emission technology to solve the crisis of wastewater treatment, nutrient removal and production of high-value products. [ABSTRACT FROM AUTHOR]

Environmental context: The increasing global demand for platinum and palladium for the development of new technologies will likely enhance their biogeochemical mobility. However, our understanding of the environmental risks of these metals remains incomplete. To help fill this knowledge gap, we determined the toxicity of various forms of platinum and palladium on a green alga. We found that palladium was more toxic than platinum and that platinum toxicity depended on the form tested. Rationale: Chemical equilibrium-based models such as the biotic ligand model (BLM) can be used to predict metal toxicity towards aquatic organisms. However, some metals such as platinum (Pt) and to a lesser extent palladium (Pd) are known to be kinetically hindered, i.e. reactions between these elements and ligands in solution might be slow relative to the biota exposure time. The BLM applicability may thus be limited for these metals and their ecological risk assessment may require consideration of their initial form of entry in aquatic ecosystems. Methodology: This study investigates the relationship between inorganic Pt and Pd initial speciation and their bioavailability and toxicity toward the unicellular green alga Raphidocelis subcapitata. Chloro- or amino-coordinated Pt and Pd complexes such as PtIICl42−, PtIVCl62−, PtII(NH3)42+, PdIICl42− and PdII(NH3)42+ were examined in 96-h algae exposure experiments to determine growth inhibition and metal accumulation. Investigation of the complex stability over time of the tested complexes was carried out using spectrophotometry measurements and kinetic calculations. Results: Similar accumulation and no toxicity (half maximal effective concentration, EC50 > 150 µg L−1) were observed for both in our tested conditions. Nevertheless, evidence of PtIICl42− dissociation was observed whereas PtII(NH3)42+ was stable. Exposure to PtIVCl62− showed stronger algal growth inhibition (EC50 = 142 µg L−1) than exposure to PtIICl42− but similar accumulation. This phenomenon might be partly explained by the generation of free chloride radicals through PtIV reduction in the presence of light. Similar accumulation and toxicity were observed for both PdIICl42− (EC50 = 4.69 µg L−1) and PdII(NH3)42+ (EC50 = 2.40 µg L−1). Discussion: These results were coherent with the relatively rapid speciation changes of the PtII complexes as observed and modelled. We therefore conclude that the initial speciation of the studied chloro- and amino-coordinated PtII and PdII complexes is not a determining parameter of their accumulation and toxicity towards R. subcapitata. Environmental context. The increasing global demand for platinum and palladium for the development of new technologies will likely enhance their biogeochemical mobility. However, our understanding of the environmental risks of these metals remains incomplete. To help fill this knowledge gap, we determined the toxicity of various forms of platinum and palladium on a green alga. We found that palladium was more toxic than platinum and that platinum toxicity depended on the form tested. (Image credit: J. Michaud-Valcourt.) [ABSTRACT FROM AUTHOR]

Dissolved organic matter and nutrients released from leaf litter are important cross‐ecosystem resources supporting freshwater food webs. Dissolved organic matter supports heterotrophic organisms in freshwater communities. However, the role of nutrients released from leaf litter in the autochthonous production in aquatic ecosystems is not well understood. Therefore, we investigated how dissolved nutrients released from leaf litter affect algal growth, biomass production, and cellular elemental ratios. Specifically, we experimentally examined the response of green algae to nitrogen (N) and phosphorus (P) released from leaf litter of 11 temperate tree species and the degree of deficiency of nutrient elements other than N and P relative to algal demand in these litter leachates by supplementing these elements. We found that algal growth did not significantly increase with dissolved N or P in the leaf leachates. In contrast, algal biomass production increased with dissolved N concentration, regardless of amendment. Algal growth and production limitation by deficiency of elements other than N and P was found only in the leachate of Japanese hemlock, indicating that the concentrations or release efficiencies of these elements in this leaf litter were lower than those of N and P relative to algal requirements. More importantly, leaf litter leachates from different tree species altered algal cell quotas and C:N:P ratios, which would affect secondary production. These results suggest that variations in leaf litter leachate stoichiometry caused by vegetation change would affect the abundance and chemical composition of phytoplankton, and thus the trophic transfer efficiency between phytoplankton and herbivorous zooplankton. [ABSTRACT FROM AUTHOR]

Synthetic biology has advanced in creating artificial microbial and algal communities, but technical and evolutionary complexities still pose significant challenges. Traditional methods, like microscopy and pigment analysis, are limited in throughput and resolution. In contrast, advancements in full-spectrum cytometry enabled high-throughput, multidimensional analysis of single cells based on size, complexity, and spectral fingerprints, offering more precision and flexibility than conventional flow cytometry. This study uses full-spectrum cytometry to analyze synthetic algal–microbial communities, enabling rapid species identification and enumeration. The workflow involves recording individual spectral signatures from monocultures, using autofluorescence to capture populations of interest, and creating a spectral library for further analysis. This spectral library was used for the analysis of the synthetic phytoplankton communities, revealing differences in spectral signatures. Moreover, the synthetic consortium experiment monitored algal growth, comparing results from different instruments, highlighting the advantages of the spectral virtual filter system for precise population separation and abundance tracking. By capturing the entire emission spectrum of each cell, this method enhances understanding of algal–microbial community dynamics and responses to environmental stressors. The development of standardized spectral libraries would improve the characterization of algal communities, further advancing synthetic biology and phytoplankton ecology research. [ABSTRACT FROM AUTHOR]

The global population increase during the last century has significantly amplified freshwater demand, leading to higher wastewater (WW) production. European regulations necessitate treating WW before environmental. Microalgae have gained attention for wastewater treatment (WWT) due to their efficiency in remediating nutrients and pollutants, alongside producing valuable biomass. This study investigates the phycoremediation potential of a Chlorella-like strain isolated from urban WW in a 600L-scale system under winter conditions. Experiments in December 2021 and February 2022 tested the strain's adaptability to varying environmental conditions, particularly temperatures (min-max temperature range: from −3.69 to 10.61 °C in December and −3.96 to 17.61 °C in February), and its ability to meet legal discharge limits. In December, low temperatures algal growth. Nitrates showed an RE of about 92%, while ammonia slightly decreased (RE, about 32%), and phosphorous remained unchanged. In February, mild temperatures increased algal density (33.3 × 106 cell mL−1) and, at the end of experiment, all nutrients were below legal limits with very high RE % (NH4+, 91.43; PO43− 97.32). Both trials showed an E. coli RE, % = 99%. The study highlights the potential of microalgae for WWT and the importance of considering seasonal variations when implementing these systems. [ABSTRACT FROM AUTHOR]

In recent years, heavy rainfall disasters linked to climate change have become more frequent, raising concerns about the release of chemicals stored in factories. Assessing chemical contamination during such emergencies therefore necessitates the development of a quick and easy method for evaluating hazardous contaminants in combination with toxicity testing. This study proposes a "toxicity screening" method that combines biological response testing and chemical analysis to systematically evaluate hazardous contaminants in emergency situations. The toxicity screening method evaluates the water quality in three steps, including water quality measurements and a delayed fluorescence (DF) assay, metal content measurements and a DF assay, and targeted screening analysis and a DF assay. The efficacy of this method was tested using industrial wastewater from 14 locations. Seven of the samples were non-toxic, while the other seven samples were toxic, displaying no observed effect concentration (NOEC) values ranging from 0.625 to 20%. Two toxic samples in the first phase possessed high total chlorine concentrations (0.4 mg L−1) and conductivities (2200 mS m−1), indicating that the main sources of toxicity were residual chlorine and a high salt concentration. In the second phase, metal content analysis identified metals as the toxicity cause in four samples. In the third phase, the organic contaminants were analyzed, and tri-n-octyl phosphate (TNOP) was detected at a concentration of 0.00027 mg L−1. The results of solid-phase extraction experiments and exposure tests with TNOP alone indicated that the contribution of TNOP to the toxicity was negligible and that chemicals not adsorbed on the solid-phase extraction cartridges were the cause of toxicity. The proposed method can therefore be considered effective for disaster-related water quality assessment, delivering results within 12 days. [ABSTRACT FROM AUTHOR]

While molecular methods have begun to transform ecology, most algal biodiversity is still studied using the classical approach of identifying microalgae by light microscopy directly in sample material or using cultures. In this study, we compare both approaches (light microscopy and metagenomics as a molecular approach) using the freshwater ponds of the Eifel National Park in Germany as a case study. The ponds were found to be rich in desmids by light microscopy. A total of 299 species representing 81 genera were identified by light microscopy. While the molecular method does not currently allow species identification in most cases, we were able to identify 207 different algal genera. In total, 157 genera were detected only by metagenomics, 50 genera were found with both methods, and 31 genera were found by light microscopy, highlighting the need to continue using light microscopy in addition to a molecular approach. The metagenomics method has several advantages over the light microscopy method: (1) deeper assessment of alpha biodiversity, (2) better abundance numbers, and (3) complete coverage of all living matter. The latter is also a significant improvement over metabarcoding, as universal PCR primers are not available. [ABSTRACT FROM AUTHOR]

Macroalgae are a natural oceanic resource of inexhaustible abundance for the biomass energy industry with growth rates that are three to four times greater than those of terrestrial plants. The objective of this study was to evaluate the sustainability of macroalgae as biomass for biorefining through two investigations. Firstly, the deposition of macroalgae was sampled through 28 collections on seven beaches in the city of Maceió, Brazil, over a two-year period using a zigzag sampling method, covering a deposition area of 135,000 m2. From this, it was estimated that daily collection would yield 5.03 t/ha of dry biomass. Secondly, the calorific values of macroalgal biomass energy and pellet compounds were calculated. The lower calorific value (8.82 MJ/kg) found from a compound of 13 species analyzed was similar to that of the main biomass used in Brazil to obtain energy, i.e., sugarcane bagasse, which has been evaluated as 8.91 MJ/kg. Macroalgal biomass in the form of condensed energy pellets was found to have a higher calorific value of 20.18 MJ/kg, i.e., 1.2% greater than the average for terrestrial biomass pellets. Based on the results obtained, it was observed that macroalgal biomass has the possibility of becoming a new renewable feedstock with potential for bioenergy. The estimates for the deposition of biomass show possibilities for producing biofuels from marine algal raw material, which provides scope for creating another sustainable alternative for global energy issues with a reduction in environmental problems. [ABSTRACT FROM AUTHOR]

Marine toxins produced by marine organisms threaten human health and impose a heavy public health burden on coastal countries. Lately, there has been an emergence of marine toxins in regions that were previously unaffected, and it is believed that climate change may be a significant factor. This paper systematically summarizes the impact of climate change on the risk of marine toxins in terms of changes in seawater conditions. From our findings, climate change can cause ocean warming, acidification, stratification, and sea-level rise. These climatic events can alter the surface temperature, salinity, pH, and nutrient conditions of seawater, which may promote the growth of various algae and bacteria, facilitating the production of marine toxins. On the other hand, climate change may expand the living ranges of marine organisms (such as algae, bacteria, and fish), thereby exacerbating the production and spread of marine toxins. In addition, the sources, distribution, and toxicity of ciguatoxin, tetrodotoxin, cyclic imines, and microcystin were described to improve public awareness of these emerging marine toxins. Looking ahead, developing interdisciplinary cooperation, strengthening monitoring of emerging marine toxins, and exploring more novel approaches are essential to better address the risks of marine toxins posed by climate change. Altogether, the interrelationships between climate, marine ecology, and marine toxins were analyzed in this study, providing a theoretical basis for preventing and managing future health risks from marine toxins. [ABSTRACT FROM AUTHOR]

In this study, the regulation of abscisic acid (ABA) on cell growth and lipid biosynthesis was investigated under salt-induced stress in Chlorella pyrenoidosa. It is found that as suffering from only salt stress, although the lipid content of single cell was improved, the inhibitory effects of stress on cell proliferation was visible. When the algal cells were exposed to salt stress and ABA conditions, lipid productivity was increased (45.35 mg L-1 d-1) by 1.17-fold compared to that of control cells (20.91 mg L-1 d-1), and the inhibition to cell growth was relieved. Transcriptomic analysis revealed that after adding ABA, these genes involved in antioxidant activity, jasmonic acid (JA) biosynthesis, and lipid biosynthesis were upregulated. Subsequently, we observed that the levels of glutathione, total antioxidant capacity, trehalose, and JA were elevated and the levels of reactive oxygen species were reduced. This study presents an effective approach to improve lipid production in algal cells, a new mechanism on that ABA alleviates intracellular oxidative stress through JA signaling pathway was elaborated. [ABSTRACT FROM AUTHOR]

In recent years, the number of scientific studies in the Antarctic and Arctic regions has increased considerably. While scientific studies allow us to explore the untouched nature of the region and better understand the global climate, they also raise various ecological concerns such as wastewater, air pollution and habitat destruction. This threatens the flora and fauna of the polar regions, negatively affecting biodiversity. It is crucial that we protect the fragile ecosystems of the polar regions through sustainable research practices and international cooperation to prevent pollution, protect habitats and prevent the introduction of invasive species. The Antarctic Treaty and other protocols prohibit the discharge of wastewater into the sea without treatment. For this reason, many research bases in Antarctica have established facilities to treat wastewater. These facilities ensure that wastewater is treated and returned to the sea without harming the environment. However, the wastewater treatment process generates a significant amount of solid waste. As this waste accumulates in the treatment plants, it has to be transported back to the mainland. Antarctica's remoteness and challenging geographical conditions make solid waste transportation logistically difficult and costly. In order to solve these problems, it was aimed to use the algal blooms occurring in Antarctica in the treatment process by cultivating them in wastewater. In the study, it was found that the Antarctic microalgae can be cultivated in domestic wastewater in Antarctic bases and have a high potential for the proposed activities by having approximately 30% of protein content. [ABSTRACT FROM AUTHOR]

The efficient growth of microalgae in sewage wastewater presents a sustainable approach for the recovery of valuable products, such as lipids and hydrocarbons. This study focuses on bench-scale cultivation and optimization to enhance the growth rates and biomass productivity of Scenedesmus sp., Chlorella vulgaris, and Spirulina platensis. The performance of bench-scale reactors under controlled conditions was investigated to maximize algal growth and biomass productivity. The objective of this study employed a series of bench-scale experiments populated using Box-Behnken in Design Expert, Design of Experiments (DOE) to identify optimal configurations. Key parameters, including pH (6.5 - 10), illumination period of light: dark (0:24, 6:18, 12:12. 18:6, 24:0), and growth medium to wastewater ratio of (0:4, 1:3, 2:2, 3:1, 4:0) were systematically varied to assess their effects on microalgal growth. The results demonstrated that specific conditions significantly influenced algal growth and overall lipid productivity. Using Bold's Basal Medium (BBM) for cultivation, Scenedesmus sp. achieved the highest growth rate of 0.86/d with biomass productivity of 39 × 104 cells/mL/d. Chlorella vulgaris performed best with a growth rate of 0.434/d and 24.38 × 104 cells/mL/d. Spirulina platensis maximum growth rate achieved 0.268/d and 23.36 × 104 cells/mL/d. Bench scale experiments further identified and incorporated optimal cultivation conditions, achieving higher growth rates and biomass productivity. These findings demonstrated the potential of optimized bench-scale reactors, providing a scalable solution for biofuel production using bubble columns, airlift reactors and industrial applications. This research contributes to the development of sustainable biofuel production technologies aligning with global efforts to reduce environmental impact and promote renewable energy sources. [ABSTRACT FROM AUTHOR]

Rhodolith beds are one of the major marine coastal ecosystems. Knowing the spatial distribution, environmental characteristics and composition is not only scientifically pertinent but also crucial to allow comparisons in case of changes due to local and global anthropogenic pressures. With slow algal growth rates, high associated diversity and potential importance as nursery grounds, rhodolith beds are present along the Brazilian coast of the Southwest Atlantic Ocean. This study provides an updated map of shallow and mesophotic rhodolith distribution after a systematic literature review. The prevailing oceanographic conditions along most parts of the Brazilian coast render the environment suitable for the developing rhodolith beds (a total of 68 taxa in this review), with 63 taxa along the East Brazilian Shelf, seven taxa for the North Brazilian Shelf and 10 taxa in the South Brazilian Shelf. According to composition, shallow and mesophotic communities were more similar in each large marine ecosystem than among them. In addition to gaps in terms of distribution, there are uncertainties about the taxonomic composition of the rhodoliths, associated fauna and flora and oceanographic and geological characteristics of the bottoms, which call attention to the importance of further studies, mainly in the mesophotic. This review provides a more precise distribution of these habitats along the Brazilian coast of the Southwest Atlantic Ocean. It contributes to a more detailed taxonomic composition of calcareous algae in an extremely relevant marine ecosystem, which is crucial for many species, including the endemic kelp, Laminaria abyssalis. [ABSTRACT FROM AUTHOR]

Algal growth depends strongly on phosphorus (P) as a key nutrient, underscoring the significance of monitoring P levels. Algal species display a sensitive response to fluctuations in P availability, notably through the expression of alkaline phosphatase (AP) when challenged with P-depletion. As such, alkaline phosphatase activity (APA) serves as a valuable metric for P availability, offering insights into how algae utilize and fix available P resources. However, current APA quantification methods lack single cell resolution, while also being time- and reagent consuming. Microfluidics offers a promising cost-effective solution to these limitations, providing a platform for precise single-cell analysis. In this study, a trap-based microfluidic device was integrated with a commercially available AP live stain to study the single cell APA response of a model algae strain, Chlamydomonas reinhardtii, when exposed to different exogenous P levels. A three-step culture-starve-spike process was used to induce APA in cells cultured under two different basal P levels (1 and 21 mM). When challenged with different spiked P levels (ranging from 0.1–41 mM), C. reinhardtii cells demonstrated a highly heterogeneous APA response. Two-way ANOVA confirmed that this response is influenced by both spiked and basal P levels. Utilizing an unsupervised machine learning approach (HDBSCAN), distinct subpopulations of C. reinhardtii cells were identified exhibiting varying levels of APA at the single-cell level. These subpopulations encompass significant groups of individual cells with either notably high or low APA, contributing to the overall behavior of the cohorts. Considerable intrapopulation differences in APA were observed across cohorts with similar average behavior. For instance, while some cohorts exhibited a concentrated distribution around the overall average APA, others displayed subpopulations dispersed across a wider range of APA levels. This underscores the potential bias introduced by analyzing a small number of cells in bulk, which may skew results by overrepresenting extreme behavioral subpopulations. The findings if this study highlight the need for analytical approaches that account for single cell heterogeneity in APA and demonstrate the utility of microfluidics as a well-suited means for such investigations. This study illuminates the complexities of APA regulation at the single cell level, providing crucial insights that advance our understanding of algal phosphorus metabolism and environmental responses. [ABSTRACT FROM AUTHOR]

In order to explore the feasibility of using algae to treat the fly ash leachate from a safe landfill site, leachate samples taken from a certain safe landfill site in Wenzhou City were treated with two different microalgae, Chlorella vulgaris and Scenedesmus obliquus, and the effectiveness of each treatment was evaluated in terms of its efficiency of pollutant removal. The effects of conditions such as pretreatment of leachate by sterilization, the initial concentration of leachate, and the addition of nutrients on pollutant removal efficiency and algae growth were studied. Sterilization of the leachate was found to have a relatively small impact on the growth of C. vulgaris and S. obliquus, as well as the removal of pollutants from the leachate. Therefore, sterilization treatment may not be necessary for engineering applications. Algal growth and the removal of pollutants were optimal when the leachate was used at a concentration of 10%, but when the leachate concentration was 30% or higher, the growth of both algae was weakened. The inclusion of 0.2 g/L K2HPO4·3H2O and 0.06 g/L ammonium ferric citrate in the system led to higher algal growth and pollutant removal. The chlorophyll a levels of C. vulgaris and S. obliquus were 555.53% and 265.15%, respectively, and the nitrogen removal rates were also the highest, reaching 59.51% and 56.69%, respectively. This study optimized the cultivation conditions of a microalgae treatment leachate system, providing technical support and a theoretical basis for the practical engineering of a harmless treatment of leachate. [ABSTRACT FROM AUTHOR]

As two significant pollutants, the increased concentrations of copper ions and microplastics in coastal waters pose a substantial threat to the health of marine ecosystems. This study explored the individual and combined toxic effects of copper ions and microplastics on the marine diatom Skeletonema costatum. The results indicated that copper ions at a concentration of 0.05 mg/L exerted a negative impact on the growth of S. costatum; however, the influence of microplastics on algal cell growth was more complex: there was no significant inhibition of algal cell growth observed within the first 72 h of cultivation, but a pronounced negative effect on cell growth was noted between 72 and 96 h, with high concentrations (10.00 mg/L) of microplastics even causing a premature stagnation phase in algal cell growth. When both pollutants were present simultaneously, their impact on cell growth was similar to that of the microplastic pollution group, yet the growth condition was better than that of the copper ion pollution group. Through investigation of adsorption rates and toxicity mitigation rates, it was found that the adsorption of copper ions by microplastics was a significant reason for the improved growth condition of algal cells in the mixed pollution group compared to the copper ion pollution group. However, in the later stages of cultivation, the inhibitory effect of microspheres on algal cell growth counteracted their mitigating effect on copper ion toxicity. This study provides a reference for evaluating the impact of microplastics and heavy metals on coastal ecosystem health and for revealing the interactions between different pollutants. [ABSTRACT FROM AUTHOR]

Increasing the marine carbon dioxide (CO 2) absorption capacity by adding alkaline minerals into the world's oceans is a promising marine carbon dioxide removal (mCDR) approach to increase the ocean's CO 2 storage potential and mitigate ocean acidification. Still, the biological impacts of dispersion of alkaline minerals need to be evaluated prior to its field deployment, especially the impacts of the initial discharge causing local and temporary extreme alkalinity/pH changes. In this study, the toxicity effect on marine microalgae of two commonly used alkaline minerals, calcium hydroxide (Ca(OH) 2) and magnesium hydroxide (Mg(OH) 2), was determined by adding the same equivalent molar concentration of hydroxyl ions. Cultures of marine green microalgae Tetraselmis suecica were exposed to Ca(OH) 2 or Mg(OH) 2 , in concentrations mimicking the initial high concentrations following a dispersion scenario from a ship. A short-term exposure with high-alkaline mineral concentration called "dispersion phase" was followed by a dilution step and a "regrowth" phase over 6 d. There was no detectable effect of Mg(OH) 2 treatment on algae growth either after the dispersion phase or during the regrowth phase, compared to control treatments. The Ca(OH) 2 treatment resulted in very few living algal cells after the dispersion phase, but a similar growth rate was observed during the regrowth phase as was for the Mg(OH) 2 and control treatments. Standardized whole effluent toxicity (WET) tests were carried out with a range of Mg(OH) 2 concentrations using a sensitive marine diatom, Skeletonema costatum, which confirmed the relatively low toxicity effect of Mg(OH) 2. Similar biological effects were observed on natural microalgae assemblages from a local seawater source when applying the same Mg(OH) 2 concentration range and exposure time used in the WET tests. The results suggest that Mg(OH) 2 is relatively safe compared to Ca(OH) 2 with respect to marine microalgae. [ABSTRACT FROM AUTHOR]

The surplus phosphorus in aquatic environments trigger eutrophication, an irreversible pollution stage marked by the rapid growth of algae and water plants, a decline in dissolved oxygen levels, and the emergence of dead zones. To address this critical issue, this study focuses on the removal of phosphorus in form of phosphate from aqueous solutions. The research involves the synthesis and characterization of FeCl3‐immobilized melamine‐formaldehyde‐urea resin, an innovative adsorbent, its characterization through Fourier transform infrared spectroscopy, and the evaluation of its adsorption capacity based on Langmuir and Freundlich equilibrium models. The experimental adsorption data fits well with pseudo‐second order kinetic model. Optimal adsorption parameters are carried with batch adsorption technique for 60 min using 0.5 g of adsorbent at pH = 2, achieving 15.55 mg g−1 adsorption capacity, and conducting experiments with tap‐water samples to replicate real‐world scenarios. The research findings have the potential to advance sustainable wastewater treatment technologies and contribute to the mitigation of nutrient pollution in aquatic ecosystems, addressing a pressing environmental concern. [ABSTRACT FROM AUTHOR]

Dissolved oxygen (DO) level at the sediment–water interface is one key factor controlling redox-sensitive processes, such as nutrient cycling. Microcosm experiments with sediment collected from three reservoirs were performed to quantify the influences of water column oxygenation (oxic, anoxic, oxygen fluctuation), sediment characteristics (grain size distribution, total nitrogen and total phosphorus contents, microbial activities), and their interactions on nutrient fluxes from sediments to the water column. Algal growth bioassays were also performed using water from the microcosms to determine which conditions produced the most favorable growth conditions. Anoxic conditions increased the release of dissolved inorganic nitrogen (DIN), mainly as ammonium and phosphates, compared to the other DO conditions. Such effects were likely due to an inhibition of the nitrification–denitrification coupling process for DIN and a reductive dissolution of Fe (III) oxides for phosphates. Following this increased nutrient availability, algal growth in the bioassays was the highest in water collected from microcosms exposed to anoxic conditions. Under both oxic and anoxic conditions, the percentage of fine sediment particles led to decreasing DIN and phosphates fluxes by reducing the nutrient diffusion rate from sediments to the water column. Finally, both DO and sediment grain size controlled the contribution of sediments to reservoir eutrophication. [ABSTRACT FROM AUTHOR]

Simple Summary: Macroalgae in natural marine areas play an important role in mitigating ocean climate change. The complexity of natural conditions also makes it necessary to study macroalgae not only by considering the effects of changes in a single factor but also by exploring the coupled effects of different environmental conditions on macroalgae. Therefore, in this study, two species of macroalgae were used as experimental subjects to observe their growth processes under different co-treatments of temperature and CO2 concentration. The results of this study can provide a reference for how natural macroalgae can cope with future changes in ocean climate. To investigate the ecological impacts of macroalgae in the framework of shifting global CO2 concentrations, we conducted a study utilizing Ulva fasciata and Sargassum horneri specimens sourced from the Ma'an Archipelago in Zhejiang Province on how ocean acidification (OA) and temperature changes interact to affect the photosynthetic physiological responses of macroalgae. The results of the study showed that OA reduced the tolerance of U. fasciata to bright light at 20 °C, resulting in more pronounced photoinhibition, while 15 °C caused significant inhibition of U. fasciata, reducing its growth and photosynthetic activity, but OA alleviated the inhibition and promoted the growth of the alga to a certain extent. The tolerance of S. horneri to bright light was also reduced at 20 °C; the inhibition was relieved at 15 °C, and the OA further improved the algal growth. The Relative Growth Rate (RGR), photosynthetic pigment content, and the release of the dissolved organic carbon (DOC) of U. fasciata were mainly affected by the change in temperature; the growth of the alga and the synthesis of metabolites were more favored by 20 °C. A similar temperature dependence was observed for S. horneri, with faster growth and high metabolism at 15 °C. Our results suggest that OA reduces the tolerance of macroalgae to high light at suitable growth temperatures; however, at unsuitable growth temperatures, OA effectively mitigates this inhibitory effect and promotes algal growth. [ABSTRACT FROM AUTHOR]

Chrysophytes are a diverse group of stramenopile protists comprising a variety of taxa with different cell organizations. Here, we morphologically and genetically characterize a novel chrysophyte genus isolated from three freshwater localities in the Czech Republic, described as Globulochrysis compacta gen. nov. sp. nov. The genus is well characterized by the frequent formation of closely packed cells, developing into large, spherical sporangia. This alga also forms solitary cells, mucilaginous colonies, amoebae, and teardrop-shaped zoids. We also investigated the morphologically similar genus Chrysotilos, isolated from its type locality in the Austrian Alps. In culture, Chrysotilos showed characteristic neustonic growth, which was, however, not observed in Globulochrysis. Phylogenetic analyses based on 18S rRNA and rbcL genes showed that these two algae belong to two distinct lineages. Whereas Chrysotilos was inferred within the clade Hibberdiales, Globulochrysis formed a completely new lineage within the order Hydrurales. Globulochrysis is described as a new genus in Hydrurales, Chrysophyceae. The genus is characterized by closely packed cells. The phylogenetic position of neustonic Chrysotilos is determined. [ABSTRACT FROM AUTHOR]

1. The objective of this study was to test the dose response of dietary supplementation with algae extracts rich in marine-sulphated polysaccharides (MSP1 and MSP2) on the growing performance, body composition at slaughter and caecal microbiota of broiler chickens. 2. Male broiler Ross 308 chicks 1-d-old were distributed into eight groups, a control group (unsupplemented), four groups supplemented with increasing doses of algae extract MSP1 (40, 81, 121 and 162 g/ton feed) and three groups supplemented with increasing doses of algae extract MSP2 (40, 81 and 162 g/ton feed). Each group comprised six pens of 56 chickens. 3. All chickens were reared under challenging conditions, i.e. high rearing density of 42 kg/m2, fed growing and finishing diets containing, palm oil, rye and high levels of wheat and subjected to short daily fasting periods. The growth performance was recorded during rearing. At 10, 22 and 31 d of age, 12 chickens per group were euthanised to collect the caecal contents and determine microbiota composition and short-chain fatty acid levels. At d 35, the quality of litter and the condition of feathers, footpads and tarsals were scored. At d 36, 7 chickens per pen were slaughtered under commercial conditions to determine carcass composition and breast meat quality (ultimate pH and colour). 4. Algal extract MSP1 increased the weight of the caeca and butyrate concentration in the caeca at d 22 (p ≤ 0.05). It increased the ultimate pH of breast fillet measured after slaughter at d 36 (p ≤ 0.05). Moreover, the group receiving 162 g/t MSP1 had a more diverse microbiota at d22. However, algal extract MSP2 had negligible effect on the different measured parameters. [ABSTRACT FROM AUTHOR]

It is crucial to investigate the effects of mixtures of contaminants on aquatic organisms, because they reflect what occurs in the environment. Cadmium (Cd) and nickel (Ni) are metals that co‐occur in aquatic ecosystems, and information is scarce on their joint toxicity to Chlorophyceae using multiple endpoints. We evaluated the effects of isolated and combined Cd and Ni metals on multiple endpoints of the chlorophycean Raphidocelis subcapitata. The results showed that Cd inhibited cell density, increased reactive oxygen species (ROS) production (up to 308% at 0.075 mg L−1 of Cd), chlorophyll a (Chl a) fluorescence (0.050–0.100 mg L−1 of Cd), cell size (0.025–0.100 mg L−1 of Cd), and cell complexity in all concentrations evaluated. Nickel exposure decreased ROS production by up to 25% at 0.25 mg L−1 of Ni and Chl a fluorescence in all concentrations assessed. Cell density and oxygen‐evolving complex (initial fluorescence/variable fluorescence [F0/Fv]) were only affected at 0.5 mg L−1 of Ni. In terms of algal growth, mixture toxicity showed antagonism at low doses and synergism at high doses, with a dose level change greater than the median inhibitory concentration. The independent action model and dose‐level–dependent deviation best fit our data. Cadmium and Ni mixtures resulted in a significant increase in cell size and cell complexity, as well as changes in ROS production and Chl a fluorescence, and they did not affect the photosynthetic parameters. Environ Toxicol Chem 2024;43:1855–1869. © 2024 SETAC [ABSTRACT FROM AUTHOR]

The field experiment was carried out at Central Research Farm, Gayeshpur, BCKV, Nadia, West Bengal, India during the Rabi season (October, 2021 to March, 2022) with the aim to study the effects of different biostimulants for growth, yield and quality of tomato. The treatments were T1 (Control or untreated), T2 (Bayfolan Algae @ 1.5 ml l-1), T3 (Bayfolan Algae @ 2 ml l-1), T4 0(Bayfolan Algae @ 2.5 ml l-1), T5 (Isabion @2 ml l-1), T6 (Bayfolan Algae @ 5 ml l-1) and T7 (Isabion @ 1.5 ml l-1). Analysis of variance clearly revealed the significant effects of biostimulants with different treatments in respect to growth, yield and quality parameters of tomato. The treatment T4 (Bayfolan Algae @ 2.5 ml l-1) recorded significantly maximum plant height (82.47 cm), number of branches plant-1 (7.04) at 60 DAT, fruit weight (74.63 g), maximum average yield plant-1 (3.26 kg, yield plot-1 (130.18 kg) and yield ha-1 (872.32 q). The same treatment T4 of Bayfolan Algae @ 2.5 ml l-1 also recorded maximum equatorial diameter (6.92 cm), maximum polar diameter (5.80 cm) and highest values of TSS (5.08 °brix), highest lycopene (5.05 mg 10-1) and ascorbic acid (26.74 mg g-1) content even which is economically viable and emerged as best treatment for getting better growth, yield and quality of Tomato. [ABSTRACT FROM AUTHOR]

Global warming can affect biomass accumulation and the dynamics of periphytic communities, potentially altering their role in aquatic ecosystem functioning. We conducted a 38-day mesocosm experiment to investigate the effects of an increase in winter temperature on periphyton biomass accumulation under eutrophic conditions. We evaluated the warming effect on colonization phases, identifying the most affected phase. The experiment had two treatments (control: current winter temperature of 23.5 ℃, warming: + 5.7 ℃ under IPCC scenario). It was carried out in growth chambers under controlled temperature, light, and humidity. Periphyton and water samplings were performed on days 3, 6, 9, 13, 17, 21, 27, and 38. The increase in temperature did not affect the organic matter accrual rate of the periphyton. However, it negatively affected the net and gross accrual rate of the algal biomass. Ash-free dry mass and chlorophyll-a ratio in the periphyton increased at higher temperatures, indicating a decrease in autotrophic components in the periphyton in the warming treatment. We detected losses in algal biomass during the intermediate and advanced colonization phases. Our results showed a decrease in periphytic algal biomass with an increase in average temperature in winter. In conclusion, a warming scenario can negatively influence periphyton biomass in eutrophic ecosystems, where algal growth in the community is generally unfavorable. [ABSTRACT FROM AUTHOR]

The freshwater snails and mussels are recognized as ecosystem engineers owing to their ability to influence the ecological processes. We investigated the effect of the snail Filopaludina bengalensis and the mussel Lamellidens marginalis alone and in interaction with the macrophyte Lemna minor on the ecological processes (nutrient dynamics, microbial account, sediment properties and periphytic algal growth) of the freshwater ecosystem through a mesocosm experiment. Both the snail and mussel promoted the growth rate of L. minor; however, the presence of snail negatively influenced the growth of periphyton. The biogeochemical process was affected by the presence of snails and mussels. Macrophyte association further influenced this biogeochemical process. Snail and mussel enhance the growth of heterotrophic bacteria and phosphate solubilising bacteria in the sediment. Likewise, the presence of macrophyte also positively influences the microbial growth. The activities of the benthic fauna like the mussels and the snails can be considered a useful process for the sustenance of the microbes and the macrophytes representing a pattern of bottom-up regulation. [ABSTRACT FROM AUTHOR]

In this study, we investigated a species‐specific algal–bacterial co‐culture that has recently attracted worldwide scientific attention as a novel approach to enhancing algal growth rate. We report that the type of interaction between Chlorella vulgaris and bacteria of the genus Delftia is not solely determined by species specificity. Rather, it is a dynamic process of adaptation to the surrounding conditions, where one or the other microorganism dominates (temporally) depending on the growth conditions, in particular the medium. Under laboratory conditions, we found that Delftia sp. had a negative effect on C. vulgaris growth when co‐cultured in a TAP medium. However, the co‐culture of algae and bacteria under BG‐11 and BG‐11 + acetic acid resulted in an increase in algal concentration compared to algal cultures without bacteria under the same conditions. Additional chemical analysis revealed that the presence of different carbon (the main organic carbon source—acetic acid in TAP or BG‐11 + acetic acid medium and inorganic carbon source—Na2CO3 in BG‐11 or BG‐11 + acetic acid medium) and nitrogen (NH4Cl in TAP medium and NaNO3 in BG‐11 or BG‐11 + acetic acid medium) species in the growth medium was one of the main factors driving the shift in interaction type. [ABSTRACT FROM AUTHOR]

Excess nutrient pollution contributes to the formation of harmful algal blooms (HABs) that compromise fisheries and recreation and that can directly endanger human and animal health via cyanotoxins. Efforts to quantify the occurrence, drivers, and severity of HABs across large areas is difficult due to the resource intensive nature of field monitoring of lake nutrient and chlorophyll‐a concentrations. To better characterize how nutrients interact with other environmental factors to produce algal blooms in freshwater systems, we used spatially explicit and temporally matched climate, landscape, in‐lake characteristic, and nutrient inventory data sets to predict nutrients and chlorophyll‐a across the conterminous US (CONUS). Using a nested modeling approach, three random forest (RF) models were trained to explain the spatiotemporal variation in total nitrogen (TN), total phosphorus (TP), and chlorophyll‐a concentrations across US EPA's National Lakes Assessment (n = 2,062). Concentrations of TN and TP were the most important predictors and, with other variables, the RF model accounted for 68% of variation in chlorophyll‐a. We then used these RF models to extrapolate lake TN and TP predictions to lakes without nutrient observations and predict chlorophyll‐a for ∼112,000 lakes across the CONUS. Risk for high chlorophyll‐a concentrations is highest in the agriculturally dominated Midwest, but other areas of risk emerge in nutrient pollution hot spots across the country. These catchment and lake‐specific results can help managers identify potential nutrient pollution and chlorophyll‐a hot spots that may fuel blooms, prioritize at‐risk lakes for additional monitoring, and optimize management to protect human health and other environmental end goals. Plain Language Summary: When lakes receive large amounts of nutrients from the surrounding landscape due to fertilizer runoff or other sources of nutrient pollution, they can develop algal blooms. Algal blooms are harmful to the lake ecosystem and sometimes produce toxins which are dangerous to humans and animals. To assess this issue, lake chlorophyll‐a, a measure of algal presence, is monitored. This monitoring is limited in reach due to the expense of in‐lake sampling and the limited resolution of satellite technology. However, there is a wealth of climate, nutrient, landscape, and in‐lake characteristic data for the conterminous US (CONUS) which explains much of what contributes to nutrient pollution and algal growth. Here, we use this data in a machine learning model to predict nutrient (total nitrogen and total phosphorus) and chlorophyll‐a concentrations in about 112,000 lakes in the CONUS. We found that high chlorophyll‐a concentrations are more likely in the Midwest where agriculture is prevalent, but other areas with high lake chlorophyll‐a concentrations are present across the CONUS in nutrient pollution hot spots. These predictions of lake nutrient and chlorophyll‐a concentrations can help managers identify areas of concern, prioritize at‐risk lakes for testing, and target management to protect human health and the environment. Key Points: Chlorophyll‐a and nutrient concentrations in ∼112,000 lakes were predicted using widely available national data sets and machine learningNutrients far outweigh other environmental predictors in driving chlorophyll‐a concentrations in lakesWith more information about likely chlorophyll‐a concentrations, managers can prioritize lakes at risk for harmful algal bloom production [ABSTRACT FROM AUTHOR]

The article investigates the distribution of phytoplankton and algal diversity and density on Safilguda Lake in Hyderabad, India. The study identifies different classes of phytoplankton including Euglenophyceae, Cyanophyceae, Chlorophyceae and Bacillariophyceae. It also examines the impact of different environmental conditions on variation in phytoplankton species composition.

Background and Objective: Bio fertilizers are one of the prominent components of sustainable agricultural systems to reduce the inputs of chemical fertilizers. The aim of the current study was to evaluate the effects of biochar and foliar use of algae extract on the growth and some physiological traits of Tanacetum balsamita L. Materials and Methods: The effects of biochar (zero, 10 and 20 tons per hectare) and foliar application of Ascophyllum nodosum extract (zero, 2 and 4 ml.L-1 ) were assayed on the growth and physiological responses of Tanacetum balsamita as a factorial experiment based on the randomized complete block design with three replications during 2019-2020 under the field condition. Results: The interactions of biochar × algae foliar application influenced the dry weight, leaf area, essential oil content and also the protein, phenolics, flavonoids, nitrogen, phosphorus and potassium content of plants. The utmost plant dry weight, leaf area, proteins, phenolics, flavonoids, nitrogen, phosphorus and potassium content was recorded in 20 ton/ ha of biochar × 2 and 4 ml L-1 of algae extract and, 10 ton/he of biochar × 4 ml L-1 algae treatment. The highest chlorophyll index belonged to the application of 10 and 20 ton/ha of biochar × 4 ml L-1 of algae extract. 20 ton/ha biochar × 4 ml.L-1 of algae extract enhanced plant height up to 76 cm which was 59% higher than the control. 20 ton/ ha biochar × 4 ml.L-1 of foliar treatment increased the essential oil yield in plants. Conclusion: The overall results revealed that 20 ton/ha biochar along with foliar spraying of 4 ml L-1 algae extract had promising effects on essential oil yield of Tanacetum balsamita. The results with some more detailed studies would be advisable to the extension section. [ABSTRACT FROM AUTHOR]

The paper presents the experimental study of the influence of a 50 Hz extremely-low-frequency (ELF) electromagnetic field (EMF) on the growth of microalgae Chlorella vulgaris in a BG11 culture medium. Comparative experimental determinations carried out under reference conditions (microalgae growth without exposure to EMF) and with exposure to a homogeneous 50 Hz EMF of various intensities highlighted the fact that EMF has a major impact on both the growth speed and the nitrogen and phosphorus content of the obtained algal mass. Through spectrophotometry and gravimetric determinations, it was found that the lag time was reduced from approximately 8 h (reference) to approximately 6 h for EMF of 2 V/m, 4.5 h for EMF of 5 V/m, 3.2 h for EMF of 10 V/m, and 2.5 h for EMF of 15 V/m. In the stimulation with 15 V/m EMF, the maximum biomass growth rate was 2.75 times higher than the reference, leading to a 2-fold increase in the rate of exhaustion of nutrients, especially phosphorus, in the culture medium. The specific chemical analyses for N-NO3, total nitrogen TNb, and total phosphorus Pt highlighted that the N-NO3 content of the culture medium decreased by 58 mg/L/day at 15 V/m EMF compared to 43 mg/L for the reference. The Pt content decreased to 90% depletion after approximately 80 h for the reference culture medium, versus only 48 h of growth with exposure to 15 V/m ELF. The TNb content of the algal suspension in BG11 under the influence of 15 V/m EMF for 96 h of growth increased 14 times compared to the reference. This shows that nitrogen metabolization in the dispersed air was significantly stimulated. It was also found that the 50 Hz EMF also influences the nitrogen and phosphorus content of the increased algal mass. The results show the potential of EMF stimulation of Chlorella vulgaris growth, leading to an increased efficiency of algae growth reactors. [ABSTRACT FROM AUTHOR]

Background: Symbioses between primary producers and bacteria are crucial for nutrient exchange that fosters host growth and niche adaptation. Yet, how viruses that infect bacteria (phages) influence these bacteria-eukaryote interactions is still largely unknown. Here, we investigate the role of viruses on the genomic diversity and functional adaptations of bacteria associated with pelagic sargassum. This brown alga has dramatically increased its distribution range in the Atlantic in the past decade and is predicted to continue expanding, imposing severe impacts on coastal ecosystems, economies, and human health. Results: We reconstructed 73 bacterial and 3963 viral metagenome-assembled genomes (bMAGs and vMAGs, respectively) from coastal Sargassum natans VIII and surrounding seawater. S. natans VIII bMAGs were enriched in prophages compared to seawater (28% and 0.02%, respectively). Rhodobacterales and Synechococcus bMAGs, abundant members of the S. natans VIII microbiome, were shared between the algae and seawater but were associated with distinct phages in each environment. Genes related to biofilm formation and quorum sensing were enriched in S. natans VIII phages, indicating their potential to influence algal association in their bacterial hosts. In-vitro assays with a bacterial community harvested from sargassum surface biofilms and depleted of free viruses demonstrated that these bacteria are protected from lytic infection by seawater viruses but contain intact and inducible prophages. These bacteria form thicker biofilms when growing on sargassum-supplemented seawater compared to seawater controls, and phage induction using mitomycin C was associated with a significant decrease in biofilm formation. The induced metagenomes were enriched in genomic sequences classified as temperate viruses compared to uninduced controls. Conclusions: Our data shows that prophages contribute to the flexible genomes of S. natans VIII-associated bacteria. These prophages encode genes with symbiotic functions, and their induction decreases biofilm formation, an essential capacity for flexible symbioses between bacteria and the alga. These results indicate that prophage acquisition and induction contribute to genomic and functional diversification during sargassum-bacteria symbioses, with potential implications for algae growth. 1vVC6YGWLCm_DZc419o4RC Video Abstract [ABSTRACT FROM AUTHOR]

The evolution of the land plant alternation of generations has been an open question for the past 150 years. Two hypotheses have dominated the discussion: the antithetic hypothesis, which posits that the diploid sporophyte generation arose de novo and gradually increased in complexity, and the homologous hypothesis, which holds that land plant ancestors had independently living sporophytes and haploid gametophytes of similar complexity. Changes in ploidy levels were unknown to early researchers. The antithetic hypothesis is contradicted by generation cycles in Lower Devonian Rhynie chert plants, whose sporophytes and gametophytes have similar morphologies and by some Silurian sporophytes whose complexity exceeds that of Rhynie chert sporophytes. The oldest unambiguous bryophyte gametophytes (thalli) are from the upper Middle Devonian, with an unconnected sporophyte nearby. Based on the 2024 discovery that conjugate algae are paraphyletic to land plants, we present a new hypothesis for the evolution of the land plant generation cycle, focusing on labile ploidy levels and types of reproduction found in conjugate algae. Our 'sexual lability' hypothesis assumes a period of unstable generation cycles (as regards ploidy), likely with predominant clonal growth, as is common in conjugate algae, resulting in sporophytes and gametophytes of similar morphology. When sexual reproduction became stabilized, the timing of gamete fusion, meiosis, and resistant wall formation, which are heterochronic in some conjugate algae, became standardized, with wall formation permanently delayed. In our scenario, independently living adult sporophytes are the land plant ancestral condition, and life-long sporophyte retention on the gametophyte is a bryophyte apomorphy. All land plants cycle between a haploid generation that grows from spores and ends with the production of gametes and a diploid generation that grows from a zygote and ends with the production of spores. Renner and Sokoloff propose a new explanation for how this type of life cycle may have evolved from an algal ancestor. [ABSTRACT FROM AUTHOR]

Eukaryotic phytoplankton, also known as algae, form the basis of marine food webs and drive marine carbon sequestration. Algae must regulate their motility and gravitational sinking to balance access to light at the surface and nutrients in deeper layers. However, the regulation of gravitational sinking remains largely unknown, especially in motile species. Here, we quantify gravitational sinking velocities according to Stokes' law in diverse clades of unicellular marine microalgae to reveal the cell size, density, and nutrient dependency of sinking velocities. We identify a motile algal species, Tetraselmis sp., that sinks faster when starved due to a photosynthesis-driven accumulation of carbohydrates and a loss of intracellular water, both of which increase cell density. Moreover, the regulation of cell sinking velocities is connected to proliferation and can respond to multiple nutrients. Overall, our work elucidates how cell size and density respond to environmental conditions to drive the vertical migration of motile algae. [ABSTRACT FROM AUTHOR]

Rotating algal biofilm reactors (RABRs) are innovative systems designed to cultivate microalgae biofilms efficiently. In this paper, we have developed a novel mathematical model to accurately capture the growth dynamics of algae biofilms within RABR. By considering the spatial heterogeneity of the RABR, we introduce a PDE-based model that addresses the spatial variations across the substratum, enabling a more accurate simulation of biofilm growth in RABRs. The photosynthesis process is modeled through reactive kinetics, driving the growth of the algae biofilm. To analyze the system's behavior, we employ finite difference numerical methods to solve the complex PDE model. We then conduct extensive numerical simulations to understand algae biofilm growth in the RABR environment under various operational factors and environmental conditions. One primary focus in these simulations is to investigate the impact of various harvesting strategies, harvesting frequencies, light intensity, and light exposure on the overall biomass productivity of the algae biofilm. The numerical results provide valuable insights into optimizing algae biofilm growth and designing harvesting techniques in RABR systems. Our proposed novel mathematical model provides an effective platform for the theoretical investigation and design of RABRs for wastewater treatment. • New mathematical model simulates algae biofilm growth in RABRs accurately. • Incorporates photosynthesis and substratum surface heterogeneity. • Advances RABR efficiency in wastewater treatment and bioproducts. [ABSTRACT FROM AUTHOR]

This study was conducted at El-Sabahia Research Station (latitude 31°12′ N, longitude 29°58′ E) in Alexandria, Egypt to evaluate the effect of Spirulina platensis algae extract on the growth, yield, and juice quality of four sugarcane genotypes during the 2020/2021 and 2021/2022 seasons. The sugarcane genotypes tested (G.T. 54-9, G. 2003-47, G. 84-47, and G. 2004-27) were treated with four concentrations (0, 0.1, 0.2, and 0.3%) of spirulina algae extract (SE) during their development as plant cane and first ratoon crops. At harvest, the growth, physiological, and juice quality characteristics were documented, while relative chlorophyll content was measured 210 days after sowing. Spraying canes with 0.2% of SE was the most effective treatment in enhancing all of the evaluated characteristics compared to those left without SE. Cane yield was more closely correlated with stalk weight (r = 0.88), followed by leaf area index (r = 0.82), relative chlorophyll content (r = 0.82), stalk length (r = 0.76), and number of tillers (r = 0.73), while recoverable sugar yield was closely correlated (p < 0.01) with sugar content % (r = 0.76). [ABSTRACT FROM AUTHOR]

In recent years, the frequent occurrence of eutrophication problems in water bodies has been caused by changes in the climate environment and overexploitation of natural resources by humans. Chlorophyll-a, as a key indicator for water body assessment, plays an important role in eutrophication research and has a profound impact on the global biogeochemical cycle of the climate process. Studies have shown that temperature can directly or indirectly affect the concentration of chlorophyll-a by influencing the growth of algae and water quality indicators in water bodies. Considering the temperature factor in the inversion of chlorophyll-a concentration is a novel research approach. Based on the influence of temperature on chlorophyll-a concentration, we propose the idea of inverting global ocean chlorophyll-a concentration based on temperature zoning. Using monthly average remote sensing reflectance data from VIIRS (Visible and Infrared Imaging Radiometer Suite), combined with the results of temperature zoning, the OC3V(SST) model was constructed to invert the monthly average chlorophyll-a concentration in the global ocean in October 2018. The OC3V(SST) model has been validated by applying it to the remaining 11 months of January, April, July, and October in 2017, 2018, and 2019, as well as the entire 31-day dataset of October 2018. The results indicate that temperature zonation can significantly improve the inversion accuracy of chlorophyll-a and further explore the spatial distribution patterns of global chlorophyll-a concentrations across various temperature ranges based on monthly averages from the global ocean. Additionally, the study investigates the continuity issues of various models and the correlation between temperature and chlorophyll-a. [ABSTRACT FROM AUTHOR]

Species interactions are influenced by changes to the environment, such as seasonal variations in temperature, and human‐driven warming including marine heatwaves (MHWs). Alteration of species interactions, particularly those involving foundation species, can shape ecosystem structure, stability and dynamics. Marine habitats, notably seagrass meadows, are threatened by human‐driven environmental changes including MHWs which have the potential to alter trophic interactions through effects on various community members including seagrasses, epiphytic algae, and epiphytic algae grazers. Here we examined the effects of a simulated marine heatwave (control versus + 4°C) in different seasons and grazer occurrence on seagrass traits, epiphytic algae growth, grazer biomass and grazing rate. We found the season in which the MHW occurred affected the seagrass response and grazer influence. In winter, the MHW had positive effects on seagrass growth and nitrogen content and caused significant decreases in epiphytic algae growth. However, in summer, grazer presence increased seagrass growth and biomass, but growth was reduced by the interaction with the MHW. The season in which the MHW occurred affected the magnitude of change in leaf tissue isotopic values and C:N ratio, with greater changes occurring in summer. Epiphytic algal growth was markedly reduced by the interaction between all three factors, leading to the near lack of epiphyte growth in summer with grazers present under the MHW. Summer was also associated with a greater increase in snail biomass (most notably under MHW conditions), and increased snail grazing rate. From these results, we show that winter MHWs can drive increased growth of seagrasses but minimal impacts on grazers, while in summer increased grazer activity can interact with elevated temperatures from a MHW to increase their algal consumption. By examining responses across multiple trophic levels and distinct seasons, we achieve a more representative and realistic depiction of human‐induced environmental impacts on ecosystems. [ABSTRACT FROM AUTHOR]

Copyright of Sultan Qaboos University Journal for Science is the property of Sultan Qaboos University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Background: Trace elements play a crucial role in fish nutrition, with zinc (Zn) being one of the most important elements. BIO-sourced zinc nanoparticles were synthesized using the green microalga Pediastrum boryanum (BIO-ZnNPs, 29.35 nm). 30 or 60 mg/ kg dry feed of the BIO-ZnNPs (BIO-ZnNPs30 and BIO-ZnNPs60) were mixed with the Nile tilapia (Oreochromis niloticus) basal diet and fed to the fish for 8 weeks to evaluate their impact on fish growth, digestion, intestinal integrity, antioxidative status, and immunity. Results: A significant enhancement was observed in all investigated parameters, except for the serum protein profile. BIO-ZnNPs at 60 mg/kg feed elevated the activities of reduced glutathione (GSH) and catalase (CAT), enzymatic antioxidants, but did not induce oxidative stress as reflected by no change in MDA level. Fish intestinal immunity was improved in a dose-dependent manner, in terms of improved morphometry and a higher count of acid mucin-producing goblet cells. Interleukin-8 (IL-8) was upregulated in BIO-ZnNPs30 compared to BIO-ZnNPs60 and control fish groups, while no significant expressions were noted in tumor necrosis factor-alpha (TNFα), nuclear factor kappa B (NFkB), and Caspase3 genes. Conclusion: Overall, BIO-ZnNPs inclusion at 60 mg/kg feed showed the most advantage in different scenarios, compared to BIO-ZnNPs at 30 mg/kg feed. The positive effects on growth and intestinal health suggest that BIO-ZnNPs supplementation of aquafeeds has many benefits for farmed fish. [ABSTRACT FROM AUTHOR]

Microalgal hydrogen (H 2) production via photo-fermentative process is an environmentally friendly alternative to the fossil fuel-based energy. Palm kernel expeller (PKE), a low-cost biomass had presented a significant advantage as organic nutrients' source in this study to fuel the photo-fermentative process. However, the increase of PKE concentrations beyond a threshold of 15.0 g/L had led to the decrease in H 2 production. As this metabolic photo-fermentative process was driven by light illumination, it was essential to investigate the impact exerted by various light intensities on microalgal H 2 productions. Accordingly, the oxygen (O 2) concentration evolutions stemming from increasing photosynthetic dissolved oxygen (DO) concentrations within the culture mediums were evaluated and remodelled with the Andrew's substrate inhibition model. The absolute inhibition of photo-fermentation was predicted at 29.6 g/L of PKE with 0.006 g/L. day of photosynthetic oxygenation rate under a specific light intensity ranging from 100 to 500 μmol/m2s. On the other hand, at the optimum 5–15 g/L of PKE, the maximum H 2 production rate could be attained at about 46 mL-H 2 /g-biomass.day with 200 μmol/m2s of light intensity. Further increasing of light intensities had also increased the photosynthetic activities, leading to the increased DO accumulations that favoured the culture photorespirations over photo-fermentative H 2 productions. The sustainability of producing microalgal H 2 was finally verified from the recycled study using a similar PKE organic nutrients' source to continuously generate H 2 that had steadily maintained after the second cycle onwards with merely 4% of a gradual decrease until fourth cycle. [Display omitted] • Photo-fermentative H 2 production from microalgae subsisting palm kernel expeller. • Remodelled microalgal H 2 kinetics from substrate concentration and light intensity. • High photosynthesis to drive microalgae for producing photo-fermentative H 2. • Spent palm kernel expeller could sustain high iterative microalgal H 2 productions. [ABSTRACT FROM AUTHOR]

This study aimed at testing the hypothesis that free-floating plants may facilitate the growth of submerged plants under hypertrophic conditions and intermediate plant density. The effects of Lemna presence on the growth of two submerged plants (Elodea nuttallii and Ceratophyllum demersum) over a nitrogen gradient were experimentally investigated. This was complemented with analysing the presence of C. demersum and E. nuttallii in Hungary and in Germany in relation to the density of free-floating plants. Results showed a negative exponential pattern between underwater light intensity and Lemna cover. Ceratophyllum and Elodea relative growth rate decreased with increasing nitrogen concentrations and additional low Lemna density stimulated Ceratophyllum and suppressed Elodea. Elodea decreased linearly with Lemna density while Ceratophyllum showed a unimodal response. Total algal biomass (epiphytic and planktonic) was higher in Ceratophyllum than in Elodea treatments and decreased rapidly with increasing Lemna density. The field studies showed a positive relationship between Ceratophyllum and a negative one between Elodea and free-floating plant cover. This study clearly showed that free-floating plants can have either facilitating or inhibiting impact on the growth of submerged plants depending on cover density and macrophyte species. The facilitating effect on Ceratophyllum is most likely due to suppressing epiphytic algal growth. [ABSTRACT FROM AUTHOR]

The Florida Keys reef tract has rapidly shifted from a structurally complex, hard coral-dominated reef to a less rugose, soft coral-dominated reef. This transition has been facilitated by persistent anthropogenic stressors including recreational and commercial fishing and increased anthropogenic marine debris. During the summers of 2020-2022, benthic censuses were conducted to identify substrate and marine debris composition for 30 reefs in the middle Florida Keys. Inshore reefs contained higher rugosity, coral cover, and marine debris abundance primarily comprised of monofilament and rope from fishing traps. Plastic items (e.g., ropes and monofilament) overall had the highest species diversity. Additionally, marine debris appears to promote turf algae growth on inshore reefs. While is it not yet possible to determine if this pattern of high debris nearshore is due to proximity to onshore debris sources, accumulation due to higher rugosity snagging debris, or increased debris removal efforts offshore, these differences in marine debris types and abundances suggest variability in potential impacts of debris on marine biota on inshore versus offshore reefs. Therefore, the differential use of marine debris by associated biota should be considered in marine debris management practices. [ABSTRACT FROM AUTHOR]