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To investigate the effects of ocean acidification (OA) and nitrogen limitation on macroalgae growth and photophysiological responses, Gracilariopsis lemaneiformis was cultured under two main conditions: ambient (Low CO2, LC, 390 matm) and CO2 enriched (High CO2, HC, 1000 matm), with low (LN, 7 mmol L-1) and high (HN, 56 mmol L-1) nitrate. High CO2 levels decreased growth under both LN and HN treatments. HC reduced Chl a, carotenoids, phycoerythrin (PE), and phycocyanin (PC) under HN conditions, while only Chl a decreased under LN conditions. NO3 - uptake rate was restricted under LN compared to HN, while HC enhanced it under HN. Net photosynthetic O2 evolution rates did not differ between CO2 and nitrate treatments. Dark respiration rates were higher under HN, further boosted by HC. The stimulated effective quantum yield (Y(II)) corresponded to decreased non-photochemical quenching (NPQ) under HN conditions. Nitrate, not CO2, showed significant effects on the relative electron transport rate (rETRmax), light use efficiency (a) and saturation light intensity (Ik) that with lowered rETRmax and a under LN culture. Our results indicate that OA may negatively affect Gracilariopsis lemaneiformis growth and alter its photophysiological performance under different nutrient conditions. [ABSTRACT FROM AUTHOR]

The experiment was to investigate the effects of three species of macroalgae on the growth performance, physiology and biochemistry index of juvenile largemouth bass. A total of 360 juvenile largemouth bass with an initial body weight of (6.04±0.03) g were randomly divided into four groups with three replicates per group and 30 perca per replicate. Group C (Control Group) was fed a basic diet, while Groups T1, T2, and T3 were fed the basic diet supplemented with 5% Gracilaria lemaneiformis powder, 5% Asparagopsis taxiformis powder, and 5% Sargassum powder, respectively, with each group's diet being isonitrogenous and isocaloric. The experiment lasted for 57 days. The results showed that compared to Group C, the feed intake rate and feed coefficient of all experimental groups was significantly increased (P<0.05), and the protein deposition rate and fat deposition rate of Groups T2 and T3 were significantly decreased (P<0.05). The whole fish moisture content of Groups T2 and T3 was significantly increased (P<0.05), while the crude protein and crude fat concentrations were significantly decreased (P<0.05). The crude fat content in the liver of Groups T2 and T3 was significantly decreased (P<0.05). The study shows that the diet with 5% Gracilaria lemaneiformis powder, Asparagopsis taxiformis powder, and Sargassum powder respectively does not affect the growth of juvenile largemouth bass, but can improve its feeding rate and reduce the crude fat of the whole body and liver, and overall effect of juvenile largemouth bass supplemented with Sargassum powder feed is the best. [ABSTRACT FROM AUTHOR]

BACKGROUND: The drive towards ensuring the sustainability of bioresources has been linked with better valorising primary materials and developing biorefinery pipelines. Seaweeds constitute valuable coastal resources with applications in the bioenergy, biofertiliser, nutrition, pharmaceutical and cosmetic sectors. Owing to the various sought‐after metabolites they possess, several seaweed species are commercially exploited throughout Western Europe, including Ireland. Here, four commercially relevant brown (Fucus serratus and Fucus vesiculosus) and red (Chondrus crispus and Mastocarpus stellatus) seaweed species were sampled during a spring tide in July 2021 on moderately exposed shores across three coastal regions in the west of Ireland. RESULTS: Significant regional differences were identified when specimens were analysed for carbohydrates (max. 80.3 μg glucose eq mg−1 DW), proteins (max. 431.3 μg BSA eq. mg−1 DW), lipids (max. 158.6 mg g−1 DW), pigment signature and antioxidant potential. Protein content for F. serratus recorded a twofold difference between northern and southern specimens. The antioxidant potential of F. vesiculosus and M. stellatus returned greater activity compared to F. serratus and C. crispus, respectively. Multivariate analysis showed a clear latitudinal pattern across the three western coastal regions (north, west and south) for both F. vesiculosus and F. serratus. CONCLUSION: F. vesiculosus thalli from the northwest were richer in pigment content while the F. serratus thalli from the northwest were richer in antioxidants. Such biogeographic patterns in the biochemical make‐up of seaweeds need consideration for the development of regional integrated aquaculture systems and the optimisation of the biomass content for targeted downstream applications. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Macroalgae seaweeds such as Ulva lactuca and Gracilaria verrucosa cause problems on the northern coast of the Italian Adriatic Sea because their overabundance hinders the growth of cultivated clams, Rudatapes philippinarum. This study focused on the green synthesis of CuO nanoparticles from U. lactuca and G. verrucosa. The biosynthesized CuO NPs were successfully characterized using FTIR, XRD, HRTEM/EDX, and zeta potential. Nanoparticles from the two different algae species are essentially identical, with the same physical characteristics and almost the same antimicrobial activities. We have not investigated the cause of this identity, but it seems likely to arise from the reaction of Cu with the same algae metabolites in both species. The study demonstrates that it is possible to obtain useful products from these macroalgae through a green synthesis approach and that they should be considered as not just a cause of environmental and economic damage but also as a potential source of income. [ABSTRACT FROM AUTHOR]

The algae of the genus Gelidium can be found as frequent and abundant inhabitants in the rocky intertidal zone of the Mexican Atlantic. Six species of this genus have been reported in this region, but only Gelidium americanum has been confirmed with morphological and molecular tools, despite how important both tools have proven to be for the group. This research aimed to evaluate the Mexican specimens previously identified as Gelidium through morphological and molecular approaches, using rbcL and COI-5P markers. This study examined 20 specimens found living attached to the shell of a gastropod Stramonita rustica in the mid-high intertidal zone of the Mexican Atlantic and ten specimens found living on rocks. Phylogenetic analyses resolved these specimens to be an independent species closely related to G. gonzalezii, G. yangmeikengense, and G. indonesianum. Genetic distances and morphological information confirmed this. Gelidium rodrigueziae sp. nov. is described as a new species. It is distinguished from its related species by having a simpler branching pattern, a smaller number and size of medullary cells, and the smaller quantity and distribution of restricted internal rhizoid filaments around the medulla. [ABSTRACT FROM AUTHOR]

The current study sought to determine the effects of Colpomenia sinuosa and Sargassum linifolium aqueous extracts on non-enzymatic and enzymatic antioxidants in Spinacia oleracea L. leaf extract. Glutathione synthase (GSS, EC: 6.3.2.3) and -glutamyl cysteine synthetase (-GCS, EC: 6.3.2.2) are involved in the glutathione biosynthesis process. Treatment of S. oleracea with seaweed extracts increased the level of reduced glutathione (GSH), oxidized glutathione (GSSG), and total glutathione at lower concentrations. Total phenols and total flavonoids in S. oleracea leaves accumulated more rapidly after treatment with seaweed extracts. The activity of the enzyme’s phenylalanine ammonia lyase (PAL, EC: 4.3.1.25), chalcone synthase (CHS, EC: 2.3. 1.74), and chalcone isomerase (CHI, EC: 5.5.1.6) involved in the production of phenylpropanoid and flavonoid in S. oleracea leaves rose in a dose-dependent manner. Glutathione reductase (GR, EC 1.6.4.2), glutathione peroxidase (GPX, EC: 1.11.1.9), and glutathione-S-transferase (GST, EC: 2.5.1.18) are examples of antioxidant enzymes whose activity were also elevated by the treatment. In comparison to untreated plants, the treated plants' S. oleracea leaf extract significantly reduced superoxide anion, 1, 1-diphenyl-2-picrylhydrazyl (DPPH), and hydroxyl radicals. In light of this, the current findings imply that the use of seaweed extracts was found to boost the activity of the antioxidant system in Spinacea oleracea [ABSTRACT FROM AUTHOR]

We carried out an in-depth study on structural characteristics, both primary and conformational structure in solution of a novel sulfated polysaccharide from green seaweed Codium geppiorum collected in central coast of Vietnam. Primary structure of the polysaccharide was determined mainly by NMR spectra, while conformation was elucidated by using small-angle X-ray scattering method. The polysaccharide was evaluated for its cytotoxic effects on three human cancer cell lines. The results indicated that dominant structure of Codium geppiorum polysaccharide is a linear sulfated galactan, and it was composed of → 4)-β-D-Galp3S-(1 → , → 3)-β-D-Galp4S-(1 → and → 3)-β-D-Galp-(1 → residues connected through 1,3-linkages. The polysaccharide has a rodlike conformation in aqueous solution, and it shows chain association with cross-sectional radius of gyration, Rgc, around 0.70 nm as estimated from small-angle X-ray scattering measurements. The polysaccharide exhibited a significant cytotoxic activity against HT29 (colorectal adenocarcinoma), 8505c (undifferentiated thyroid carcinomas) and Hela (cervical cancer) human cancer cell lines with IC50 values of 51.85 ± 2.30, 89.30 ± 2.35 and 72.22 ± 6.73 µg/mL, respectively. [ABSTRACT FROM AUTHOR]

Intertidal macroalgae play a vital role in marine ecosystems, necessitating effective monitoring of their coverage and diversity. Traditional monitoring methods are labour-intensive and costly, prompting exploration of the use of unmanned aerial vehicles (UAVs) to characterize intertidal ecosystems. We propose an alternative process integrating UAV red-green-blue (RGB) imagery and topographic indexes to classify complex intertidal macroalgae assemblages automatically. We studied two intertidal areas capturing eight flights between May and September 2023. Orthoimages and Digital Elevation Models (DEMs) were generated. Manual segmentations for 24 classes were cropped into images of individual labels. Additional channels with five topographic indices were added to the RGB images. The resulting dataset of 6412 images was then used to train a Convolutional Neural Network (CNN). We tested the benefit of the additional topographic indices by training the CNN with and without the topographic channels. The best results were given by the inclusion of the Analytical hillshade to the RGB images, showing a relative 11.3% increase in classification accuracy. This indicates that 3D data can enhance the performance of macroalgae classification models. However, there was no significant improvement when using more than one topographic index to train the CNN. Our workflow offers a cost-effective and robust solution for intertidal macroalgae monitoring, contributing to ecological conservation efforts. [ABSTRACT FROM AUTHOR]

Environmental context: Seaweeds are known to accumulate high levels of arsenic, and cellular concentrations may reach several orders of magnitude higher than that of the surrounding environment. Arsenic may be methylated by seaweed cells and further metabolised to water-soluble arsenic-containing sugars through unknown pathways. Whether these compounds are the result of a detoxification process or are produced with a biological purpose remains to be seen. Rationale: Seaweeds are known to accumulate high levels of arsenic, which may be subsequently metabolised to small, methylated compounds or become incorporated into large biological molecules such as arsenosugars. The mechanism of arsenosugars production in macroalgae is still largely unknown. Method: This study reports the arsenic speciation of 13 brown, red and green macroalgae collected in May 2021 and February 2022. Water-soluble arsenic speciation was measured using high-performance liquid chromatography–inductively coupled plasma–mass spectrometry (HPLC-ICP-MS) after extraction with a 3% (v/v) hydrogen peroxide solution. Results: Arsenosugars were found to account for the majority of the extracted arsenic in all seaweed samples (>50%), with only small amounts of dimethylarsinate and monomethylarsonate present. Levels of toxic iAs were also low (−1). Sulfur-containing arsenosugars were the dominant arsenicals in brown macroalgae, whereas the phosphate ribose was most abundant in red and green. Discussion: The majority of seaweed species appear to have the ability to synthesise all four arsenosugar derivatives; however, it is unclear why some are produced in higher abundances. The production of arsenosugars may be an efficient way of excluding arsenic from the cytosol, or may serve as useful components in the cell wall matrix, as extremely high levels can be tolerated by the seaweed with no ill effects. AsSug-gly and AsSug-PO4 were detected in every sample analysed, which might suggest that AsSug-gly is the starting point for AsSug-PO4, which could be formed by AsSug-gly binding to phosphate-containing lipids in the cell membrane. Further studies should use both imaging and speciation techniques to investigate the formation of arsenosugars. Environmental context. Seaweeds are known to accumulate high levels of arsenic, and cellular concentrations may reach several orders of magnitude higher than that of the surrounding environment. Arsenic may be methylated by seaweed cells and further metabolised to water-soluble arsenic-containing sugars through unknown pathways. Whether these compounds are the result of a detoxification process or are produced with a biological purpose remains to be seen. (Image credit: Rebecca Sim.) [ABSTRACT FROM AUTHOR]

Macroalgal wracks can be considered unpleasant for beach users and, consequently, they are usually collected from most touristic beaches and discarded. However, seaweeds are an important source of bioactive lipid compounds, such as phospholipids, glycolipids, and n-3 polyunsaturated fatty acids (n-3 PUFA), displaying multiple health-promoting properties, including antioxidant and antimicrobial activities. The aim of this study is to characterize the lipid composition of twelve marine seaweed species (two green, six red, and four brown species) from macroalgal wracks of Gran Canaria Island, and to evaluate their potential use for several purposes, including human and animal nutrition. Lipid content, lipid classes, and fatty acid profiles of isolated specimens from the macroalgal wracks were determined. Lipid contents ranged between 0.27 and 3.17% of dry weight, with all species showing high phytosterols proportions and balanced omega-6/omega-3 (n-6/n-3) ratios. In addition, Cymopolia barbata, Asparagopsis sp., and Hypnea spinella seem to be an attractive source of both mono- and di-galactosyl-diacylglycerols, while A. stellata, Jania sp., and Lobophora sp. are relatively rich in n-3 LC−PUFA. Finally, both green algae showed the most favorable values for the nutritional indicators of cardiovascular health promotion. Overall, the macroalgal species analyzed could be considered as interesting sources for human and animal nutrition. [ABSTRACT FROM AUTHOR]

Objective: The purpose of the current study was to examine the effectiveness of green macroalgae as a novel, natural feed additive for broilers that have a greater concentration of active ingredients. Materials and Methods: Four experimental groups of 180-day-old male broiler chicks (Cobb-500) were randomly assigned, with three replicates in each group: the control group [T0, maintained only with basal diet] and three treatment groups supplemented with macroalgae for 35 days along with basal diet [T1 = 0.05% (w/w); T2 = 0.1% (w/w); T3 = 0.2% (w/w) macroalgae]. Live weight, carcass weight, and organs' weight were noted at the conclusion of the experiment. The meat quality was examined using the muscles of the thighs and breasts, and blood serum was obtained for biochemical assessment. Results: The results revealed that dietary supplementation of green macroalgae (0.1%) in broiler rations significantly (p < 0.05) improved the growth performance compared to other treated groups and controls. With increasing weight, it enhanced meat quality traits assessed by increased water holding capacity, ultimate pH, redness and yellowness, and decreased lightness of muscles in the thighs and breasts. Both the levels of serum cholesterol and abdominal fat decreased and showed no unwholesome effects on liver and kidney functions. Conclusions: For the production of safe and high-quality poultry meat, marine green macroalgae (Enteromorpha intestinalis) could be used as a potential feed additive. It enhanced the growth rate in broilers and improved meat quality and serum biochemical parameters for supplying healthy meat in the human food chain. [ABSTRACT FROM AUTHOR]

The bacterial communities related to seaweed can vary considerably across different locations, and these variations influence the seaweed's nutrition, growth, and development. To study this further, we evaluated the bacteria found on the green marine seaweed Ulva prolifera from Garorim Bay and Muan Bay, two key locations on Republic of Korea's west coast. Our analysis found notable differences in the bacterial communities between the two locations. Garorim Bay hosted a more diverse bacterial population, with the highest number of ASVs (871) compared to Muan Bay's 156 ASVs. In Muan Bay, more than 50% of the bacterial community was dominated by Pseudomonadota. On the other hand, Garorim Bay had a more balanced distribution between Bacteroidota and Pseudomonadota (37% and 35.5%, respectively). Additionally, Cyanobacteria, particularly Cyanothece aeruginosa, were found in significant numbers in Garorim Bay, making up 8% of the community. Mineral analysis indicated that Garorim Bay had higher levels of S, Na, Mg, Ca, and Fe. Function-wise, both locations exhibited bacterial enrichment in amino acid production, nucleosides, and nucleotide pathways. In conclusion, this study broadens our understanding of the bacterial communities associated with Ulva prolifera in Korean waters and provides a foundation for future research on the relationships between U. prolifera and its bacteria. [ABSTRACT FROM AUTHOR]

Groundnut, Arachis hypogaea L., is a leguminous crop widely cultivated for its edible oil seeds. It faces significant challenges from soil-borne diseases, including Sclerotium rolfsii Sacc., which severely affect groundnut production and productivity. Biological control methods offer broader treatment alternatives than traditional chemical approaches. The present study investigated the activation of defense enzymes such as peroxidase (PO), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) in groundnut plants under pot culture conditions. The plants were treated with different marine macroalgae and bioagent combinations, where inoculation with S. rolfsii was challenged. Among the nine treatments, T4 {seed treatment [ST] by Sargassum wightii extract at 2% + soil application (SA) of S. wightii at 100 g/pot + ST by Trichoderma asperellum (Tr-3) at 4 g/kg of seeds + SA with T. asperellum (Tr-3) at 50 g/pot} concentrations gave the maximum increased activities of PO (1.40 changes in absorbance min/g of leaf tissue), PPO (2.03 changes in absorbance min/g of leaf tissue), and PAL (9.56 changes in absorbance min/g of leaf tissue). In contrast, the inoculated control exhibited minimal activity of these enzymes. The increased enzyme activities were recorded until 24 days after sowing, and a gradual decrease was observed afterward. The present study showed that marine macroalgae and bioagents could enhance defense enzyme activity in groundnut plants and significantly prevent the disease caused by S. rolfsii. [ABSTRACT FROM AUTHOR]

The drug target protein β-secretase 1 (BACE1) is one of the promising targets in the design of the drugs to control Alzheimer's disease (AD). Patients with neurodegenerative diseases are increasing in number globally due to the increase in the average lifetime. Neuro modulation is the only remedy for overcoming these age related diseases. In recent times, marine bioactive compounds are reported from Phaeophyceae (Brown Algae), Rhodophyta (Red Algae) and Chlorophyta (Green Algae) for neuro-modulation. Hence, an important attempt is made to understand the binding and stability of the identified bioactive compounds from the above marine algae using BACE1 as the molecular target. The docking study shows that the bioactive compound Fucotriphlorethol A (– 17.27 kcal/mol) has good binding affinity and energy compared to other compounds such as Dieckol (– 16.77 kcal/mol), Tetraphlorethol C (– 15.12 kcal/mol), 2-phloroeckol (– 14.98 kcal/mol), Phlorofucofuroeckol (– 13.46 kcal/mol) and the co-crystal (– 8.59 kcal/mol). Further, molecular dynamics simulations studies had been carried out for β-secretase 1 complex with Fucotriphlorethol A and Phlorofucofuroeckol for 100 ns each. Results are compared with that of the co-crystal inhibitor. Molecular dynamics simulations studies also support the stability and flexibility of the two bioactive compounds Fucotriphlorethol A and Phlorofucofuroeckol with BACE1. [ABSTRACT FROM AUTHOR]

Nature derived compounds represent a valuable source of bioactive molecules with enormous potential. The sea is one of the richest environments, full of skilled organisms, where algae stand out due to their unique characteristics. Marine macroalgae adapt their phenotypic characteristics, such as chemical composition, depending on the environmental conditions where they live. The compounds produced by these organisms show tremendous potential to be used in the biomedical field, due to their antioxidant, anti-inflammatory, immunomodulatory, and anti-cancer properties. Cancer is one of the deadliest diseases in the world, and the lack of effective treatments highlights the urgent need for the development of new therapeutic strategies. This review provides an overview of the current advances regarding the anti-cancer activity of the three major groups of marine macroalgae, i.e., red algae (Rhodophyta), brown algae (Phaeophyceae), and green algae (Chlorophyta) on pancreatic, lung, breast, cervical, colorectal, liver, and gastric cancers as well as leukemia and melanoma. In addition, future perspectives, and limitations regarding this field of work are also discussed. [ABSTRACT FROM AUTHOR]

In response to a global shift towards health-conscious and environmentally sustainable food choices, seaweed has emerged as a focus for researchers due to its large-scale cultivation potential and the development of bioactive substances. This research explores the potential anticancer properties of seaweed extracts, focusing on analyzing the impact of four common edible seaweeds in Taiwan on prostate cancer (PCa) cells' activity. The study used bioassay-guided fractionation to extract Cl80 from various seaweeds with androgen receptor (AR)-inhibitory activity. Cl80 demonstrated effective suppression of 5α-dihydrotestosterone (DHT)-induced AR activity in 103E cells and attenuated the growth and prostate-specific antigen (PSA) protein expression in LNCaP and 22Rv1 cells. Additionally, Cl80 exhibited differential effects on various PCa cell lines. Concentrations above 5 μg/mL significantly inhibited LNCaP cell proliferation, while 22Rv1 cells were more resistant to Cl80. PC-3 cell proliferation was inhibited at 5 μg/mL but not completely at 50 μg/mL. A clonogenic assay showed that at a concentration of 0.5 μg/mL, the colony formation in LNCaP and PC-3 cells was significantly reduced, with a dose-dependent effect. Cl80 induced apoptosis in all PCa cell types, especially in LNCaP cells, with increased apoptotic cells observed at higher concentrations. Cl80 also decreased the mitochondrial membrane potential (ΔΨm) in a dose-dependent manner in all PCa cell lines. Furthermore, Cl80 suppressed the migration ability of PCa cells, with significant reductions observed in LNCaP, 22Rv1, and PC-3 cells at various concentrations. These compelling findings highlight the promising therapeutic potential of C. lentillifera J.Agardh and its isolated compound Cl80 in the treatment of PCa. [ABSTRACT FROM AUTHOR]

This document is a summary of a special issue of the journal Botanica Marina focused on the green seaweed Ulva. The collection of articles explores various aspects of Ulva, including its ecology, phylogeny, and practical applications in aquaculture. The articles cover topics such as taxonomy, cross-kingdom interactions with bacteria and fungi, and the cultivation of Ulva for sustainable alternatives to essential fatty acids. The special issue aims to advance our understanding of Ulva and its potential in sustainable aquaculture and ecological contexts. The collection is dedicated to the late Prof. Dr. Klaus Lüning, a renowned marine botanist who made significant contributions to the study of Ulva. The special issue is also supported by the EU-funded COST Action SeaWheat, which aims to integrate Ulva into various industries and daily life. [Extracted from the article]

Several studies have shown that endophytic fungal metabolites possess vital biological activities; nevertheless, there is a lack of knowledge regarding the medicinally important marine endophytic fungi associated with the seaweeds mainly found in the Bay of Bengal, Bangladesh. In this study, six endophytic fungi, belonging to five genera and four classes, were isolated from the well-known chlorophyte, Ulva sp. and were most closely related to Chaetomium globosum, Nigrospora magnoliae, Curvularia sp., Curvularia moringae, Aspergillus terreus and Collariella sp. This is the first report of these fungi as endophytes associated with Ulva sp. from the Bay of Bengal, Bangladesh. A preliminary biological evaluation of the ethyl acetate extract of each endophytic fungal crude extract was the prime objective of this research, e.g., antimicrobial assay, 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity and brine shrimp lethality bioassay. Evaluation of test results revealed that each fungal crude extract possessed one or more relevant biological activities. Preliminary chemical screening using TLC and NMR spectroscopic analysis revealed the presence of several secondary metabolites in the crude fungal extracts. These findings suggest that the marine endophytic fungus may be a valuable source for investigating potentially bioactive chemicals or leads for novel drug candidates. [ABSTRACT FROM AUTHOR]

Actinomycetota, associated with macroalgae, remains one of the least explored marine niches. The secondary metabolism of Actinomycetota, the primary microbial source of compounds relevant to biotechnology, continues to drive research into the distribution, dynamics, and metabolome of these microorganisms. In this study, we employed a combination of traditional cultivation and metagenomic analysis to investigate the diversity of Actinomycetota in two native macroalgae species from the Portuguese coast. We obtained and taxonomically identified a collection of 380 strains, which were distributed across 12 orders, 15 families, and 25 genera affiliated with the Actinomycetia class, with Streptomyces making up approximately 60% of the composition. Metagenomic results revealed the presence of Actinomycetota in both Chondrus crispus and Codium tomentosum datasets, with relative abundances of 11% and 2%, respectively. This approach identified 12 orders, 16 families, and 17 genera affiliated with Actinomycetota, with minimal overlap with the cultivation results. Acidimicrobiales emerged as the dominant actinobacterial order in both macroalgae, although no strain affiliated with this taxonomic group was successfully isolated. Our findings suggest that macroalgae represent a hotspot for Actinomycetota. The synergistic use of both culture‐dependent and independent approaches proved beneficial, enabling the identification and recovery of not only abundant but also rare taxonomic members. [ABSTRACT FROM AUTHOR]

Durvillaea incurvata is a brown macroalgae of ecological, social, and economic importance subjected to a drastic increase in harvesting pressure over the last decade in Chile. In this study, we performed an experimental transplantation of juveniles of D. incurvata, assessing the potential use as a restocking technique. Different types of restocking devices and attaching substrates were constructed. Differences in the D. incurvata re-attachment probability among the substrates and devices were not observed, and a high percentage of juvenile mortality was observed. However, reattached juveniles increased their length, holdfast diameter, and weight. The experiment revealed that juveniles of D. incurvata have a good capacity for reattachment and growth on artificial substrates after transplantation. This technique could be used for the species stock enhancement, although further studies are needed to optimize the process and increase the juvenile's reattachment. [ABSTRACT FROM AUTHOR]

The present investigation was carried out to evaluate the antimicrobial and antioxidant activities of four seaweed species gathered from the western coast of the northern Egyptian Red Sea using two different solvents: dichloromethane/methanol (1:1 v/v) and ethyl acetate. These species are Turbinaria ornata, Padina pavonica (Phaeophyta), Actinotrichia fragilis (Rhodophyta) and Ulva lactuca (Chlorophyta). The antimicrobial activity of the crude extracts was assessed in vitro against three microorganisms: Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcus aureus) and the yeast Candida albicans by the disc diffusion method. Both extracts of T. ornata and P. povonica showed a wide spectrum of antibacterial activity, however, the fungal entity Candida albicans was not inhibited in any way by any of the examined seaweed extracts. The efficacy of both solvents was discussed. The antioxidant activity was detected using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The highest activity was recorded in the dichloromethane/methanol extract of the brown seaweed T. ornata. On the other hand, the lowest activity was recorded in the ethyl acetate extract of the green seaweed Ulva lactuca. These findings revealed the potential of the Red Sea brown seaweeds as a promising candidate to act as antibacterial and antioxidant agent in medical applications. Further work is required to identify and separate the exact active compounds responsible for the biological activity. [ABSTRACT FROM AUTHOR]

Oomycetes are ubiquitous heterotrophs of considerable economic and ecological importance. Lately their diversity in marine environments has been shown to be greatly underappreciated and many lineages of intracellular holocarpic parasites, infecting micro- and macro-algae, remain to be fully described taxonomically. Among them, pathogens of marine red algae have been studied extensively as they infect important seaweed crops. Throughout the 20th century, most intracellular, holocarpic biotrophic oomycetes that infect red algae have been assigned to the genus Olpidiopsis Cornu. However, 18S rRNA sequencing of Olpidiopsis saprolegniae, the species considered the generitype for Olpidiopsis, suggests that this genus is not closely related to the marine pathogens and that the latter requires a nomenclatural update. Here, we compile and reanalyze all recently published 18S rRNA sequence data for marine holocarpic oomycetes, with a particular focus on holocarpic pathogens of red algae. Their taxonomy has been revised twice over the past four years, with suggestions to transfer them first into the genus Pontisma and then Sirolpidium, and into a monogeneric order, Pontismatales. We show however, that previously published topologies and the proposed taxa Pontisma, Sirolpidium, and Pontismatales are unsupported. We highlight that name changes that are unfounded and premature create confusion in interested parties, especially concerning pathogens of marine red algae that infect important seaweed crops. We thus propose that the names of these holocarpic biotrophic parasites of red algae are retained temporarily, until a supported topology is produced with more genetic markers to enable the circumscription of species and higher-level taxa. [ABSTRACT FROM AUTHOR]

The immune system acts as a defense mechanism against foreign antigens. Impairment of the immune system leads to the development of chronic diseases such as respiratory infections, cancer, cardiovascular diseases, and neurodegeneration. Macrophages, natural scavengers that are part of innate immunity, are known to directly participate in scavenging foreign antigens. The functional modulation of macrophages could be an effective treatment for pathogens. Seaweeds are marine macroalgae known to exhibit multiple bioactive properties. Thus, this study evaluated the immune-enhancing properties of marine brown algae extracts of Sargassum horneri (SH), Undaria pinnatifida (UP), and Sargassum fusiforme (SF) on murine macrophage cells. The results showed that all three algal extracts stimulated cell proliferation. SH and UP outshined SF in enhancing the expression levels of IL-1β, TNF-α, and IL-6 at almost all the concentrations tested as compared to SF which showed similar effects only at 200 or 400 μg/mL. A similar trend was seen in TNF-α, NO, and PGE2 production. Additionally, only SH and SF could enhance the mRNA expression levels of IL-12, and only SH upregulated the mRNA expression level of IL-10. The algal extracts also enhanced the phagocytosis activity of macrophages at 50–400 μg/mL for SH and 100–400 μg/mL for UP and SF. In conclusion, we found that these algal extracts could be considered immunomodulators that enhance the functional activity of macrophages. [ABSTRACT FROM AUTHOR]

Background: Solar radiation is primarily composed of ultraviolet radiation (UVR, 200 − 400 nm) and photosynthetically active radiation (PAR, 400 − 700 nm). Ultraviolet-B (UVB) radiation accounts for only a small proportion of sunlight, and it is the primary cause of plant photodamage. The use of chlorofluorocarbons (CFCs) as refrigerants caused serious ozone depletion in the 1980s, and this had led to an increase in UVB. Although CFC emissions have significantly decreased in recent years, UVB radiation still remains at a high intensity. UVB radiation increase is an important factor that influences plant physiological processes. Ulva prolifera, a type of macroalga found in the intertidal zone, is intermittently exposed to UVB. Alternative oxidase (AOX) plays an important role in plants under stresses. This research examines the changes in AOX activity and the relationships among AOX, photosynthesis, and reactive oxygen species (ROS) homeostasis in U. prolifera under changes in UVB and photosynthetically active radiation (PAR). Results: UVB was the main component of solar radiation impacting the typical intertidal green macroalgae U. prolifera. AOX was found to be important during the process of photosynthesis optimization of U. prolifera due to a synergistic effect with non-photochemical quenching (NPQ) under UVB radiation. AOX and glycolate oxidase (GO) worked together to achieve NADPH homeostasis to achieve photosynthesis optimization under changes in PAR + UVB. The synergism of AOX with superoxide dismutase (SOD) and catalase (CAT) was important during the process of ROS homeostasis under PAR + UVB. Conclusions: AOX plays an important role in the process of photosynthesis optimization and ROS homeostasis in U. prolifera under UVB radiation. This study provides further insights into the response of intertidal macroalgae to solar light changes. [ABSTRACT FROM AUTHOR]

To limit global warming below 2°C by 2100, we must drastically reduce greenhouse gas emissions and additionally remove ~100–900 Gt CO2 from the atmosphere (carbon dioxide removal, CDR) to compensate for unavoidable emissions. Seaweeds (marine macroalgae) naturally grow in coastal regions worldwide where they are crucial for primary production and carbon cycling. They are being considered as a biological method for CDR and for use in carbon trading schemes as offsets. To use seaweeds in carbon trading schemes requires verification that seaweed photosynthesis that fixes CO2 into organic carbon results in CDR, along with the safe and secure storage of the carbon removed from the atmosphere for more than 100 years (sequestration). There is much ongoing research into the magnitude of seaweed carbon storage pools (e.g., as living biomass and as particulate and dissolved organic carbon in sediments and the deep ocean), but these pools do not equate to CDR unless the amount of CO2 removed from the atmosphere as a result of seaweed primary production can be quantified and verified. The draw‐down of atmospheric CO2 into seawater is via air‐sea CO2 equilibrium, which operates on time scales of weeks to years depending upon the ecosystem considered. Here, we explain why quantifying air‐sea CO2 equilibrium and linking this process to seaweed carbon storage pools is the critical step needed to verify CDR by discrete seaweed beds and nearshore and open ocean aquaculture systems prior to their use in carbon trading. [ABSTRACT FROM AUTHOR]

The relative frequency of sexual versus asexual reproduction governs the distribution of genetic diversity within and among populations. Most studies on the consequences of reproductive variation focus on the mating system (i.e., selfing vs. outcrossing) of diploid‐dominant taxa (e.g., angiosperms), often ignoring asexual reproduction. Although reproductive systems are hypothesized to be correlated with life‐cycle types, variation in the relative rates of sexual and asexual reproduction remains poorly characterized across eukaryotes. This is particularly true among the three major lineages of macroalgae (green, brown, and red). The Rhodophyta are particularly interesting, as many taxa have complex haploid–diploid life cycles that influence genetic structure. Though most marine reds have separate sexes, we show that freshwater red macroalgae exhibit patterns of switching between monoicy and dioicy in sister taxa that rival those recently shown in brown macroalgae and in angiosperms. We advocate for the investigation of reproductive system evolution using freshwater reds, as this will expand the life‐cycle types for which these data exist, enabling comparative analyses broadly across eukaryotes. Unlike their marine cousins, species in the Batrachospermales have macroscopic gametophytes attached to filamentous, often microscopic sporophytes. While asexual reproduction through monospores may occur in all freshwater reds, the Compsopogonales are thought to be exclusively asexual. Understanding the evolutionary consequences of selfing and asexual reproduction will aid in our understanding of the evolutionary ecology of all algae and of eukaryotic evolution generally. [ABSTRACT FROM AUTHOR]

Fleshy macroalgae dominate the hard bottom, shallow waters along the Western Antarctic Peninsula (WAP). Although there are numerous reports on their ecology, geographic distribution, and to a lesser extent, vertical (depth) distribution in the northern portions of the WAP, much less is known farther south along the central portion of the WAP. Here we provide the first report of the vertical distributions of brown and red fleshy macroalgae in this region based on scuba-derived collections at 14 study sites between southern Anvers Island (64.8°S, 64.4°W) in the north and central Marguerite Bay (68.7°S, 67.5°W) in the south. Although several overstory brown macroalgal species that can be common along the northern WAP including Desmarestia anceps and Cystosphaera jacquinotii are mostly absent from the central WAP, the vertical distributions of the brown macroalgae Desmarestia menziesii and Himantothallus grandifolius are similar to the northern WAP even though their percent cover is much lower. Likewise, the vertical distribution of the 14 most widespread red macroalgae, where they occur, mirrored those known from the northern part of the WAP even though macroalgal cover, biomass, and total species richness declined markedly to the south across this region due to increasing sea ice concentrations. [ABSTRACT FROM AUTHOR]

Context. Limitation in soil organic matter interferes with plant growth and productivity. Chemical fertilisers can provide limiting nutrients to plants, especially in barren soil, but they have detrimental *Correspondence to: Sedat Çam Department of Biology, Faculty of Arts and Sciences, Harran University, Haliliye, S¸anlıurfa 63050, Turkey Email: sedatcam@harran.edu.tr effects on living organisms; therefore, plant growth-promoting (PGP) rhizobacteria may be an alternative to synthetic fertilisers to improve plant tolerance to nutrient stress. Aims. This study evaluated the effects of single and co-inoculation of two PGP rhizobacterial strains with macroalgae (Cladophora glomerata) extract on barley growth. We also tested the ability of the respective strains to produce biofilm and exopolysaccharide (EPS) at different pH values under in vitro conditions. Methods. Plants were cultivated in an organic matter-limited alkaline soil under Handling Editor: Caixian Tang field conditions. Key results. All treatments increased barley growth parameters to some extent. Growth parameters increased most in Bacillus + macroalgae extract (B + MA) and Bacillus + Azotobacter + macroalgae extract (B + A + MA) treatments. These two treatments significantly enhanced shoot length by 22.9-25.7%, dry weight of shoot + spike by 118.2-154.5%, total weight of grains by 76.5-78.1%, and number of grains per spike by 94.8-112.1% in comparison with the control. The respective two treatments also increased biofilm formation and EPS production in response to alkaline pH. Conclusions. Barley productivity may be increased by using PGP strains with greater potential to produce biofilm and EPS, and inoculating them with macroalgae extract. The B + MA treatment could be applied singly or in combination with Azotobacter. Implications. Single or co-inoculation of such PGP bacteria with macroalgae extract may be commercialised to enhance barley productivity in organic matter-limited soils. [ABSTRACT FROM AUTHOR]

Among marine primary producers, macroalgae support complex and productive coastal food webs, but coastal primary production relies on terrigenous inputs and remineralized organic matter which both vary seasonally. An approach combining stable isotope and biochemical analyses enables a better characterization of macroalgae specificities and highlights environmental influences on their chemical signature. This study compared the isotopic signature and biochemical composition of 22 Mediterranean macroalgae belonging to Rhodophyta (red algae), Phaeophyceae (brown algae) and Chlorophyta (green algae) between March and November 2010 to capture the differences in species chemical signatures potentially driven by metabolic traits or environmental drivers. Carbon stable isotope values were evidenced as a good proxy of specific carbon metabolism: low values observed in red algae could be related to the reported absence of carbon concentrating mechanisms (CCMs) in this group while higher values were driven by strong CCM activity in green algae. Biochemical patterns also differed between groups: soluble carbohydrates were a major component for red algae, while lipids and proteins dominated in brown algae, and insoluble carbohydrate concentrations were high in green algae. Variation within species across two collection times could be related to environmental changes and algal metabolism. δ15N values confirm the efficiency of this parameter as a proxy of the impact of human influence in the Bay of Marseille. Isotopic and biochemical content was measured in 22 Mediterranean macroalgae. Carbon descriptors are related to the metabolism of the specific macroalgal group. Seasonal variation of descriptors correlates with environmental variability. [ABSTRACT FROM AUTHOR]

Macroalgae, commonly known as seaweed, are foundational species in coastal ecosystems and contribute significantly to coastal primary production globally. However, the impact of macroalgal decomposition on benthic biological nitrogen fixation (BNF) after deposition to the seafloor remains largely unexplored. In this study, we measure BNF rates at three different sites at the Big Fisherman's Cove on Santa Catalina Island, CA, USA, which is representative of globally distributed rocky bottom macroalgal habitats. Unamended BNF rates varied among sites (0.001-0.05 nmol N g-1 h-1) and were generally within the lower end of previously reported ranges. We hypothesized that the differences in BNF between sites were linked to the availability of organic matter. Indeed, additions of glucose, a labile carbon source, resulted in 2-3 orders of magnitude stimulation of BNF rates in bottle incubations of sediment from all sites. To assess the impact of complex, autochthonous organic matter, we simulated macroalgal deposition and remineralization with additions of brown (i.e., Macrocystis pyrifera and Dictyopteris), green (i.e., Codium fragile), and red (i.e., Asparagopsis taxiformis) macroalgae. While brown and green macroalgal amendments resulted in 53- to 520-fold stimulation of BNF rates--comparable to the labile carbon addition--red alga was found to significantly inhibit BNF rates. Finally, we employed nifHsequencing to characterize the diazotrophic community associated with macroalgal decomposition. We observed a distinct community shift in potential diazotrophs from primarily Gammaproteobacteria in the early stages of remineralization to a community dominated by Deltaproteobacteria (e.g., sulfate reducers), Bacteroidia, and Spirochaeta toward the latter phase of decomposition of brown, green, and redmacroalgae. Notably, the nifH-containing community associated with red macroalgal detritus was distinct from that of brown and green macroalgae. Our study suggests coastal benthic diazotrophs are limited by organic carbon and demonstrates a significant and phylum-specific effect of macroalgal loading on benthic microbial communities. [ABSTRACT FROM AUTHOR]

In a closed, or zero water exchange, greenhouse aquaculture system, this study examined the interaction between the aggregation flocs in the mono- and co-cultivation of Pasific white shrimp, Litopenaeus vannamei (300 individuals/m3) with macroalgae, Ulva lactuca f. fasciata at different densities of Ulva (1, 2 and 3 g/l). The investigation was conducted under zero water exchange conditions. The accumulated flocs were compared between the various treatment groups: without Ulva (Treatment Control Group), Ulva at 1 g/l density (T1: Treatment 1), Ulva at 2 g/l (T2: Treatment 2), and Ulva at 3 g/l (T3: Treatment 3). Ultimately, it was determined that Ulva cultivation using the Biofloc system actually helped to ensure the water quality in the zero water exchange culture system during the 35-day experimental period with reduced cyanophyte densities, that can cause toxic algal blooms in aquaculture systems. This was interpreted to result from the fact that Ulva is a naturally occurring bioremediation agent. [ABSTRACT FROM AUTHOR]

The present study was carried out to determine the antitumor and antioxidant activities of the seaweed Durvillaea antarctica. Extraction and purification of polysaccharides from D. antarctica were performed. They were characterized by FT‐IR and GC–MS, identifying isomers of arabinose, fucose, mannose, and galactose. The antioxidant capacity of polysaccharides was analyzed using the ABTS method (14.3 ± 0.5 μmol TE g−1 PS) and the DPPH method (21.82 ± 0.32 μmol TE g−1 PS). The antitumor capacity of polysaccharides was studied by MTT colorimetric assays in human leukemia, colon, breast, and lung cancer cell lines, obtaining the lowest IC50 in colon cancer (19.99 μg mL−1). In the line of healthy human gingival fibroblasts (HGF‐1), an IC50 of 444.39 μg mL−1 was obtained. Flow cytometry in the HL60 cell line showed that polysaccharides at concentrations higher than IC50 inhibited cell proliferation, demonstrating a possible antitumor capacity in vitro. In the proteomic analysis with HGF‐1, nine proteins involved in different biological processes were identified. In conclusion, polysaccharides from D. antarctica could be considered powerful nutraceuticals, mainly against colon cancer. [ABSTRACT FROM AUTHOR]

Background Marine macroalgae ('seaweeds') are a diverse and globally distributed group of photosynthetic organisms that together generate considerable primary productivity, provide an array of different habitats for other organisms, and contribute many important ecosystem functions and services. As a result of continued anthropogenic stress on marine systems, many macroalgal species and habitats face an uncertain future, risking their vital contribution to global productivity and ecosystem service provision. Scope After briefly considering the remarkable taxonomy and ecological distribution of marine macroalgae, we review how the threats posed by a combination of anthropogenically induced stressors affect seaweed species and communities. From there we highlight five critical avenues for further research to explore (long-term monitoring, use of functional traits, focus on early ontogeny, biotic interactions and impact of marine litter on coastal vegetation). Conclusions Although there are considerable parallels with terrestrial vascular plant responses to the many threats posed by anthropogenic stressors, we note that the impacts of some (e.g. habitat loss) are much less keenly felt in the oceans than on land. Nevertheless, and in common with terrestrial plant communities, the impact of climate change will inevitably be the most pernicious threat to the future persistence of seaweed species, communities and service provision. While understanding macroalgal responses to simultaneous environmental stressors is inevitably a complex exercise, our attempt to highlight synergies with terrestrial systems, and provide five future research priorities to elucidate some of the important trends and mechanisms of response, may yet offer some small contribution to this goal. [ABSTRACT FROM AUTHOR]

Seaweed, or macroalgae, is a diverse group of marine plants found in various aquatic environments. Seaweed has gained attention due to its potential uses in various industries, including food, agriculture, pharmaceuticals, etc. Its proximate composition refers to the essential nutritional components that make up seaweed. The present study aimed to conduct proximate composition analysis on three different seaweeds, Valonia utricularis, Ulva reticulata and Kappaphycus alvarezii, collected from the Mandapam region coast, Rameshwaram, Tamil Nadu, India. A result of three seaweeds Valonia utricularis, Ulva reticulata and Kappaphycus alvarezii was followed ash (23.42% DW), (22.19%) and (19.7%DW). Protein was (11.5% DW), (10.11%) and (15.91%DW); lipid content was (4.24% DW), (5.27%) and (2.75%DW); crude fibre was (12.72% DW), (16.20%) and (23.51%DW); carbohydrate (31.33% DW), (27.05%) and (26.19 %DW), Total Dietary Fiber was (2.7% DW), (3.03%) and (6.76% DW). [ABSTRACT FROM AUTHOR]

Non‐native species (NNS) might become invasive and threaten biodiversity, economy and public health. Therefore, it is essential that their invasiveness risk be quantified to support conservation measures.The Azores, located in the mid‐northern Atlantic, is the crossroad of macroalgal native distributions and also present almost three times the global ratio of macroalgae reported as NNS.Aquatic Species Invasiveness Screening Kit, a decision‐support tool consisting of 49 questions for the Basic Risk Assessment (BRA) and six for the Climate Change Assessment (CCA), was applied to the 42 marine macroalgae classified as NNS in the Azores.The results indicate that 21 species pose a medium risk of becoming invasive, and 15 present a high risk under current climate conditions (BRA scores only). The combined BRA + CCA scores show that Laurencia dendroidea poses a high risk instead of a medium risk.Thirty‐three Rhodophyta species were screened, with 10 (BRA) and 11 (BRA + CCA) classified as high risk. All four Chlorophyta species ranked as high risk. Only one of the five Ochrophyta species was classified as high risk, namely Rugulopteryx okamurae, one of the most invasive species in European waters.High‐risk species are present in all islands, likely spread by the continuous maritime traffic between islands. Six of the high‐risk species are restricted to single islands (BRA and BRA + CCA scores), and efforts should be made to contain their further expansion. Asparagopsis armata, a species introduced in Europe in the 1920s, is the only high‐risk species present in all islands.Conservation measures for prevention, monitoring and control of NNS are proposed for the different islands of the Azores, including regulation of introduction pathways, prospection of areas with high risk of invasion, risk screening, eradication and containment of NNS. The involvement of stakeholders and maritime workers is also recommended. [ABSTRACT FROM AUTHOR]

Seaweed farming is a significant source of livelihood for many coastal communities in the Philippines. While it is one of the most profitable forms of aquaculture, seaweed farmers are nevertheless encouraged to participate in other business activities to provide financial security. Thus far, studies among seaweed farmers in the Philippines have primarily focused on production-related activities and market and value chains. Seaweed farmers' entrepreneurial skills have yet to be evaluated. In this study, we assess the capacity of seaweed farmers in Sorsogon, the Philippines, to undertake business ventures using the personal entrepreneurial competencies (PEC) test. We found that seaweed farmers exhibit moderate entrepreneurial competencies. There were significant differences found between the mean PEC scores across traits. "Risk-taking" and "demand for quality and efficiency" indicated a significant interaction with educational attainment. Entrepreneurial competencies among seaweed farmers may be improved by pooling tacit entrepreneurial knowledge among seaweed farmers, engaging in entrepreneurial education, and establishing and maintaining groups (cooperatives, clusters, or associations) to gain matched support from NGOs and government. [ABSTRACT FROM AUTHOR]

Marine based organisms and their bioactive compounds are very attractive in terms of biomedical area. Due to marine ecosystem have harsh environment conditions; marine algae synthesize various bioactive compounds to survive. Genus Ulva (green macro algae) or sea lettuce species are the most abundant representatives abound in coastal waters and have various bioactive compounds. Therefore, Ulva sp. is extensively researched in especially cancer treatment. In this study, the ethanol extract of Ulva rigida C. Agardh collected from Izmir Bay was investigated by MTT, LDH, TAC, TOS and HET-CAM assays to determine its anticancer potential. The extract of U. rigida showed significant cytotoxic effect on human cervix adenocarcinoma (HeLa) cells (IC50 value is 21 ± 4.84 mg/L). The extract had a moderate anti-angiogenic activity (Score value is 0.98 ± 0.3 at 50 μM concentration). Our results showed that U. rigida has a good potential cervical cancer therapy agent. [ABSTRACT FROM AUTHOR]

Nigrospora (Xylariales, Apiosporaceae) consists of species of terrestrial plant endophytes and pathogens. Nigrospora has also been reported in marine environments such as mangroves, sea fans, and macroalgae. However, limited research has been conducted on Nigrospora associated with macroalgae. Here, we isolated Nigrospora species from three types of algae (brown, green, and red algae) from Korean islands (Chuja, Jeju, and Ulleung) based on phylogenetic analyses of multigenetic markers: the internal transcribed spacers (ITS), beta-tubulin (BenA), and translation elongation factor 1 (TEF1-α). A total of 17 Nigrospora strains were isolated from macroalgae and identified as nine distinct species. The majority of Nigrospora species (seven) were found on brown algae, followed by red algae (three), and then green algae (two). To our understanding, this study represents the first account of N. cooperae, N. covidalis, N. guilinensis, N. lacticolonia, N. osmanthi, N. pyriformis, and N. rubi occurring in marine environments. Additionally, this study provides the first report of the occurrence of N. cooperae, N. covidalis, N. guilinensis, N. lacticolonia, and N. osmanthi in South Korea. This study will provide valuable insights for future research exploring the functions of fungi in macroalgal communities. [ABSTRACT FROM AUTHOR]

Macroalgae have been a key ecological component of marine ecosystems since the Proterozoic period and are common fossil forms in Cambrian Burgess Shale‐type Lagerstätten. However, in most cases, it is difficult to place these early fossil algae into modern groups because little distinctive morphology is preserved. Here, we describe a new form of macroalgae, Qingjiangthallus cystocarpium gen. & sp. nov., from the Qingjiang biota of South China. The new taxon is represented by 546 specimens remarkably preserved with characteristics that allow a phylogenetic placement into crown groups of red algae. Centimeter‐sized thalli resemble members of the extant Rhodymeniophycidae (a subclass of the class Florideophyceae), and hence suggest a florideophycean affinity, which indicates that ahnfeltiophycidaen and rhodymeniophycidaen algae may have diverged at least 518 Ma, accordant with estimations of molecular studies. The presence of possible cystocarps on Qingjiangthallus thalli suggests that evolutionary innovation of a triphasic life cycle in red algae may have occurred no later than the Early Cambrian. The branching patterns and branch width of Qingjiangthallus are consistent with the coarsely dichotomously branched morphogroup, which was previously present in the Ediacaran, Ordovician, and afterward, but absent in the Cambrian. [ABSTRACT FROM AUTHOR]

Ulva prolifera and Sargassum are two common floating macroalgae in China's coastal algal bloom events. Ulva prolifera frequently emerges concomitantly with Sargassum outbreaks, thereby presenting challenges to the monitoring of algal blooms, thereby presenting challenges to the monitoring of algae. To tackle the challenge of differentiating between Ulva prolifera and Sargassum, this study employs Sentinel-2 MSI data for spectral analysis. Notably, significant disparities in the Remote Top of Atmosphere Reflectance (Rtoa) between Ulva prolifera and Sargassum are observed. This study proposes a random forest-based algorithm for discriminating between Ulva prolifera and Sargassum in the regions of the Yellow Sea and East China Sea. The algorithm introduced in this study attains remarkable accuracy in distinguishing Ulva prolifera and Sargassum within Sentinel-2 MSI data, achieving identical F1 scores of 99.1% for both. Moreover, when tested with GF-1 WFV data, the algorithm showcases outstanding performance; this demonstrates the algorithm's robustness and its ability to mitigate the uncertainty linked to threshold selection. Simultaneously, a comparative analysis of algae distribution was conducted for both 2017 and the period from January to May 2023. Experimental results indicate that the algorithm exhibits high accuracy in distinguishing between Ulva prolifera and Sargassum. This capability will significantly enhance the monitoring of large algae in maritime regions; this holds crucial theoretical significance and offers substantial practical value in the realm of marine ecological conservation. [ABSTRACT FROM AUTHOR]

Six organic and aqueous extracts of two marine algae Stypocaulon scoparium and Halopitys incurvus were collected and studied from the Algerian west coast for their antimicrobial activities against Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli), Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus) and fungi (Candida albicans, Fusarium oxysporum f. sp. albedinis). The positive antibacterial activity with more than 10 mm diameter of inhibition zone was found by the ethanolic toluene extracts and the extract obtained by the Ethanol/Chloroform mixture of the two algae. Also, the results of the antifungal tests against Fusarium oxysporoum f. sp. albedinis have shown that the best results were obtained by the aqueous, methanol/dichloromethane and ethanolic extracts of the two algae. The methanolic and toluene extracts of Halopitys incurvus were very active with mycelial growth inhibition rates of 60% and 50%, respectively. The purification and the determination of chemical structure of active compounds from the two algae yet to be. [ABSTRACT FROM AUTHOR]

Brine discharged from seawater desalination plants impacts marine life by exposure to increased salinity and, in some cases, temperature. However, the responses of individual species to such stress remains poorly known yet their understanding is essential for assessing and predicting the impacts of seawater desalination plants. In this study, unialgal cultures obtained by the germling emergence method of 34 taxa representative of the Rhodophyta, Chlorophyta and Phaeophyceae seaweeds in the Arabian Gulf, and isolated from the vicinity of two large desalination plants in Kuwait, were subjected to increased temperature and salinity under experimental conditions in the laboratory. The dataset is complemented by measurements of seawater temperature and salinity obtained at increasing distances from the outfalls of desalination plants and along the Kuwaiti coastline including from two pristine areas, Boubiyan and Fintas. Chlorophyta, especially Ulva spp., and Phaeophyceae displayed remarkable tolerance against hypersaline and thermal stress, suggesting that this group can cope better with adverse environmental conditions. Members of the Rhodophyta were considerably more sensitive to temperature increases. [ABSTRACT FROM AUTHOR]

Regulation of tissue water potential is a key mechanism in macroalgal osmotic responses to changing external osmotic conditions, which are common in tidally influenced estuarine and intertidal systems. Nevertheless, significant knowledge gaps exist in our understanding of osmotic responses in macroalgae because few methods measure osmotic potential within macroalgal tissues. Leaf psychrometers have furthered understanding of osmotic potentials in terrestrial plant water relations, yet these have not been developed to measure the range of highly negative potential values found in marine macroalgae. To address these gaps, we present an effective, updated version of the Chardakov method to measure tissue water potential in macroalgae. Here, we present a case study examining macroalgal response in tissue water potential by two morphologically and evolutionarily distinct species, Ulva lactuca (Chlorophyta) and Hypnea musciformis (Rhodophyta) to four paired salinity and nutrient treatments at two temperatures. These treatments simulate a gradient from full coastal ocean conditions to brackish submarine groundwater discharge, an ecosystem type found on basaltic shorelines. Both algae demonstrated plasticity in osmotic response to submarine groundwater discharge with significant positive correlations between tissue water potential and proportion of submarine groundwater discharge in the treatment. These results are the first to describe macroalgal response in tissue water potential, a first step to understanding algal physiological ecology in such complex coastal environments. This revised Chardakov method is a valuable tool to better understand species-specific osmotic responses to ecologically relevant conditions, and can augment the study of other tidal systems and ontogenetic stages. [ABSTRACT FROM AUTHOR]

The IUCN Red List of Threatened Species is an authoritative tool in biodiversity conservation. Whilst IUCN criteria have been applied successfully to groups such as birds and mammals, a Red List assessment of British seaweeds in 2021 revealed that the categories to which seaweed species were assigned were dependent on how the criteria were applied. Here, this seaweed assessment is used as a case study with which to evaluate the IUCN methodology for use with 'non-standard' groups of organisms. A data-driven assessment of red (Rhodophyta), green (Chlorophyta) and brown (Phaeophyceae) seaweeds, which applied three (A, B and D) of the five IUCN criteria (A–E), categorized 13% of 617 British species as threatened. Following peer review, only 7% of species were categorized as threatened (1% Critically Endangered—CR, 3% Endangered—EN, 3% Vulnerable—VU), and 55% as Data Deficient. This reduction in species categorized as threatened suggests that strict application of the IUCN criteria may, at least for the seaweeds, over-estimate threat. As a result of this assessment, recommendations include the need for a more unified monitoring system and a review of the suitability for/application of the IUCN assessment criteria to some types of organisms. For example, in clonal populations, it is not possible to count individuals, and complex life histories cause additional complications. IUCN criteria must be applicable to a wide range of organisms, including seaweeds. [ABSTRACT FROM AUTHOR]

The aim of this study was to use unmanned aerial vehicles (UAVs) as a supplement to satellite remote sensing to accurately assess benthic seaweed biomass in intertidal zones, in order to improve inversion accuracy results and investigate the spatial distribution patterns of seaweed. By adopting non-multicollinearity vegetation indices (feature sets) from PlanetScope and Sentinel-2, and using benthic seaweed biomass inverted from multispectral UAV imagery as the label set for satellite pixel biomass values, machine learning methods (Gradient boosting decision tree, GBDT) can effectively improve the accuracy of biomass estimation results for Ulva pertusa and Sargassum thunbergii species (Ulva pertusa, R S e n t i n e l 2 2 = 0.74, R P l a n e t S c o p e 2 = 0.8; Sargassum thunbergii, R S e n t i n e l 2 2 = 0.88, R P l a n e t S c o p e 2 = 0.69). The average biomasses of Ulva pertusa and Sargassum thunbergii in the intertidal zone of Gouqi Island are 456.84 g/m2 and 2606.60 g/m2, respectively, and the total resources are 3.5 × 108 g and 1.4 × 109 g, respectively. In addition, based on the hyperspectral data, it was revealed that a major source of error is the patchy distribution of seaweed. [ABSTRACT FROM AUTHOR]

This study used four different macroalgae (Costaria costata, Hizikia fusiformis, Gracilaria verrucosa, and Codium fragile) as biosorbents to remove the heavy metals, Cd2+, Cu2+, Ni2+, and Pb2+. Among the studied macroalgae, Costaria costata showed the best biosorbent activity for heavy metal removal. A Fourier transform infrared spectroscopy analysis indicated that the cell wall structure of Costaria costata has various functional groups such as amine, sulfonate, negatively charged hydroxyl groups, and carboxyl groups. The modification of Costaria costata using HCl and NaOH was ineffective in terms of improving its biosorption capacity. The kinetic experiments and modeling data showed reaction ratios in the following descending order: Ni2+ > Cd2+ > Cu2+ > Pb2+. Additionally, the Freundlich model was able to describe the equilibrium data well except for Pb2+. The maximum heavy metal adsorption capacity for Pb2+ was 160.990 mg/g; this was higher than the other heavy metals: 45.094, 44.768, and 42.082 mg/g for Cu2+, Cd2+, and Ni2+, respectively. This means that the adsorption of heavy metals onto Costaria costata occurred via covalent bonding as opposed to electrostatic attraction. Moreover, metal biosorption by Costaria costata enhanced significantly as the initial solution pH increased from 2 to 4. Among the competing cations, Al3+ demonstrated the greatest inhibitory effect on heavy metal removal because of its high charge valence and affinity. Consequently, the dried biomass of Costaria costata could be used to potentially eliminate heavy metals from aqueous solutions due to its characteristic high efficiency, easy acquisition, low cost, and easy preparation. [ABSTRACT FROM AUTHOR]