Search Results (1,139)

Cultural eutrophication caused by human activity significantly impacts benthic ecosystems. This study investigated how different phytobenthic components—rhodophyte germlings, mesoalgal and macroalgal assemblages, and Ulva cf. lactuca—respond to nutrient enrichment in a tidal channel system in San Antonio Bay, Argentina. Two experiments were conducted: one in spring examined the interaction between nutrient enrichment (N + P, N + P + Fe) and grazing pressure on early and established algal communities, and the other in autumn assessed nutrient effects on assemblages and Ulva cf. lactuca. Results showed that early successional stages, such as germlings and mesoalgae, responded most strongly to nutrient inputs, while mature macroalgae remained largely unaffected. Significant growth of mesoalgae, with increased pigment concentrations (chlorophyll a, c, and carotenoids), occurred at the eutrophied SAO Channel in spring. Nutrient additions increased rhodophyte germlings but eventually reduced diatom-dominated mesoalgal growth. Mature macroalgae showed site-specific differences but did not respond to fertilization. Grazing effects were evident in treatments with protective cages, suggesting herbivory influences early-stage algal development. Overall, the study emphasizes the importance of the successional stage, grazing pressure, and environmental nutrient history in shaping benthic algal responses to eutrophication, offering key insights into the dynamics of coastal ecosystems under increasing nutrient stress. Full article

The development of algal bioplastics offers a promising pathway toward sustainable materials that can mitigate reliance on fossil fuel-derived plastics. This article reviews recent advances in algal cultivation, strain optimization, biopolymer extraction, and processing technologies, alongside techno-economic and life cycle assessments. Special emphasis is placed on integrated biorefinery models, innovative processing techniques, and the role of government–industry–academia partnerships in accelerating commercialization. The analysis incorporates both demonstrated algal systems and theoretical applications derived from established microbial processes, reflecting the emerging nature of this field. The environmental advantages, market readiness, and scalability challenges of algal bioplastics are critically evaluated, with reference to peer-reviewed studies and industrial pilot projects. The analysis underscores that while technical feasibility has been demonstrated, economic viability and large-scale adoption depend on optimizing yield, reducing production costs, and fostering collaborative frameworks. Future research priorities include enhancing strain performance via AI-enabled screening, expanding product valorization streams, and aligning regulatory standards to support global market integration. Full article

Background: Marine macroalgae has been studied by our research group as alternative sources of bioactive compounds with promising antiparasitic activity, particularly against Schistosoma mansoni. Objectives: This study aimed to employ a metabolomics-based approach to identify anthelminthic active compounds from the macroalgae Laurencia aldingensis Saito and Womersley 1974 and Laurencia dendroidea J. Agardh 1852. Methods: The algae were extracted using a dichloromethane/methanol mixture, followed by liquid–liquid partitioning and sequential chromatographic fractionation using solvents of varying polarities. The resulting fractions were tested for biological activity against adult Schistosoma mansoni worms. Detailed chemical characterization of the extracts was conducted via HPLC-DAD-MS/MS, with subsequent data alignment and statistical analysis (Pearson correlation) to associate specific chemical compounds with the observed bioactivity. Results: Non-polar fractions (hexane and dichloromethane) exhibited significant anthelminthic activity, substantially reducing parasite viability and reproduction. Specific subfractions obtained from the dichloromethane fraction demonstrated notable activity. Metabolomic analysis revealed considerable chemical diversity, emphasizing the presence of bromophenols and halogenated sesquiterpenes, including potentially novel compounds with therapeutic potential against schistosomiasis. Conclusions: The metabolomics approach proved effective in identifying promising bioactive compounds from Laurencia spp. macroalgae with activity against S. mansoni. Full article

The green macroalgae Ulva Linnaeus, 1753, also known as sea lettuce, is one of the most ecologically and economically significant algal genera. Its representatives occur in marine, brackish, and freshwater environments worldwide and show high adaptability, rapid growth, and marked biochemical diversity. These traits support their ecological roles in nutrient cycling, primary productivity, and habitat provision, and they also explain their growing relevance to the blue bioeconomy. This review summarizes current knowledge of Ulva biodiversity, taxonomy, and physiology, and evaluates applications in food, feed, bioremediation, biofuel, pharmaceuticals, and biomaterials. Particular attention is given to molecular approaches that resolve taxonomic difficulties and to biochemical profiles that determine nutritional value and industrial potential. This review also considers risks and limitations. Ulva species can act as hyperaccumulators of heavy metals, microplastics, and organic pollutants, which creates safety concerns for food and feed uses and highlights the necessity of strict monitoring and quality control. Technical and economic barriers restrict large-scale use in energy and material production. By presenting both opportunities and constraints, this review stresses the dual role of Ulva as a promising bioresource and a potential ecological risk. Future research must integrate molecular genetics, physiology, and applied studies to support sustainable utilization and ensure safe contributions of Ulva to biodiversity assessment, environmental management, and bioeconomic development. Full article

For nearly two decades, the Yellow Sea has experienced recurrent green tides, which are now considered the largest of their kind globally; the mechanism behind these outbreaks remains highly complex and not fully understood. This study investigates the pre-outbreak distribution, abundance, and species composition of suspended macroalgae in the Southern Yellow Sea (SYS) during 2023–2024, along with environmental parameters. The results indicate that suspended macroalgae were predominantly distributed in the nearshore waters, particularly along the shallow beaches of northern Jiangsu. Furthermore, their abundance in the surface water layer significantly exceeded that in the bottom water. A total of 1353 and 493 algal filament samples were collected in 2023 and 2024, respectively. Dominant species included Ulva prolifera, Ulva linza, Ulva flexuosa, and Blidingia sp. Nutrient levels positively correlated with filament abundance. As a primary means of rapid proliferation for U. prolifera, suspended macroalgae contribute significantly to the initial expansion of green tides. Furthermore, their abundance holds promise as a biological indicator for forecasting the scale and extent of impending blooms, thereby providing a critical foundation for elucidating the underlying outbreak mechanisms. Full article

The overabundance of Ulva australis (U. australis), a green macroalga widespread along the coastline of Jeju Island, Republic of Korea, presents a growing ecological challenge, as it can cause unpleasant odors and disturb the ecological balance. Hence, we report a sustainable valorization strategy for converting U. australis biomass into marine carbon dots (MCDs) via a facile hydrothermal carbonization process. The synthesis requires no hazardous reagents or complex instrumentation and yields highly water-dispersible MCDs with excitation-dependent fluorescence properties. Comprehensive in vitro and in vivo assessments revealed the multifunctional bioactivity of the synthesized MCDs. Moreover, in vivo fluorescence imaging at seven days post-fertilization revealed the preferential accumulation of MCDs along the vertebral column, implying a possible affinity for mineralized tissues and suggesting their utility in skeletal imaging applications. Collectively, these findings underscore the potential of U. australis-derived MCDs as biocompatible and multifunctional nanomaterials with broad biomedical applications. Full article

Bahía de La Paz is the largest bay in the southern Gulf of California. This bay is an important area with a variety of commercial fish species and other natural resources and recreational activities. Epibenthic dinoflagellates are common inhabitants of harbors, inlets and semi-enclosed coastal lagoons; they produce potent toxins that may negatively affect human health and marine biota. The purpose of the present study was to identify potentially harmful epibenthic dinoflagellates growing on macroalgae from different coastal sites of the bay to determine their species composition, abundances, seasonal distributions, interannual and spatial variations. A total of 153 quantitative samples were collected in 2015–2019 (at 10 sites during four samplings in May, June and December) mainly from macroalgae. About 23 dinoflagellate species from the genera Prorocentrum, Ostreopsis, Sinophysis, Gambierdiscus, Fukuyoa, Amphidinium, Blixaea, Bysmatrum, Cabra, Coolia, Durinskia and Plagiodinium were found as epiphytes on at least 58 macroalgal species of 42 genera. Toxigenic genera, such as Gambierdiscus, Ostreopsis, Coolia and Prorocentrum, were widespread throughout the study area. Playa El Tecolote and Playa Costa Baja were the best habitats for dinoflagellates; therefore, the two locations can be considered the beaches with the greatest risk to human health. Full article

The survival and efficacy of probiotic bacteria depend on their ability to grow under optimal conditions and withstand environmental stresses, and marine macroalgae are emerging as promising prebiotic sources that may enhance their viability. In this study the effect of Ascophyllum nodosum and Fucus vesiculosus supplementation (0.5% w/v) on Lactiplantibacillus plantarum was evaluated by assessing growth performance and stress resistance under different conditions, including temperatures (15, 25, 30, 37, 42 °C), pH levels (2.5, 3.5, 4.5, 6.5, 8.5), and enzymatic challenges (pepsin, trypsin, bile). Both algal supplements promoted faster initial growth between 25 and 42 °C, particularly at 37 °C, by reducing the lag phase and increasing the growth rate. Under acidic stress, survival exceeded 80% after 3 h, with significant improvements at pH 2.5 and 3.5 in the presence of seaweeds, while enzymatic assays demonstrated enhanced tolerance against pepsin, trypsin, and bile salts. Overall, supplementation with brown algal biomass provided modest but consistent benefits to L. plantarum growth and stress resistance, supporting the use of whole macroalgae as functional additives in probiotic formulations for both human and animal nutrition. Full article

Macroalgae-derived polyphenols have been considered as a potential source of food supplements that can enhance the nutritional value and extend the shelf life of foods. However, thermal treatment during food processing as well as storage might induce the degradation of some bioactive compounds in the extract. In the present study, the stability of the extract from the edible brown algae Ascophyllum nodosum was evaluated under thermal treatment (40–90 °C). Significant differences in TPC, RSC, and antioxidant activity were found during all treatments. The total phenol content (TPC) and antioxidant activity (DPPH scavenging activity) decreased up to 5% and 10%, respectively, after 6 h of thermal treatment, while the reducing sugar content (RSC) increased from 8 to 35% as the temperature increased from 40 to 90 °C. The stability of the extract during storage with or without exposure to air was evaluated at room temperature (25 °C) and low temperature (4 °C) for 108 h, and the influence of the solvent used to contain the extract has been investigated by studying both concentrated and non-concentrated extracts. It was found that the extract stored at 4 °C without exposure to air had a negligible TPC change, while RSC increased in the extract exposed to air, suggesting that oxygen in the air might accelerate polysaccharide degradation during storage. Antioxidant activity of extracts remained constant at both 4 and 25 °C, regardless of exposure to air. Full article

This study examined the effects of Bacillus probiotic strains on red abalone Haliotis rufescens reproductive performance. We supplemented plant- and fish-based feeds and compared them to fresh giant kelp Macrocystis pyrifera as a control diet. Over 180 days, abalone fed the plant–probiotic diet reached higher female gonadal maturation, with 56% of females attaining the maximum Visual Gonad Index (VGI 3). Additionally, plant-based treatment showed a female-biased sex ratio (1.5:1 female-to-male ratio, F:M) compared with the kelp control treatment (0.8:1 F:M). These results suggest that probiotics can improve nutrient utilization from soybean meal and may enhance the bioavailability of phytoestrogens and other bioactive compounds, contributing to reproductive outcomes. Although the mechanisms remain to be confirmed, this approach provides a promising strategy to reduce reliance on fishmeal and wild macroalgae while supporting faster reproductive cycles in abalone aquaculture. Future research should focus on biochemical validation, molecular pathways, and multigenerational trials to ensure the long-term safety and sustainability of probiotic–plant-based feeds. Full article

The remarkable conservation of soft tissues within Cambrian fossils has significantly enhanced our comprehension of the origins and evolutionary trajectories of animals, in addition to the progression of ecological intricacy. Here, we report an exceptionally preserved specimen of the lingulid brachiopod Xianshanella haikouensis from the lower Cambrian Chengjiang Lagerstätte, exhibiting branched fringes along the distal ends of its marginal setae. These structures may represent either branched setae or attached macroalgae. The diameter of the branched fringes is slightly larger than that of the marginal setae, and they exhibit third- or fourth-order bifurcations, forming a complex structure comparable in length to the shell. Both the branched fringes and marginal setae are preserved as iron oxides, as revealed by SEM and Micro-XRF analyses, a characteristic preservation mode in Chengjiang fossils. The results of Micro-CT scanning suggest that these branched fringes are preserved along almost the entire distal end of marginal setae. Comparable branched fringes are reminiscent of those found in annelids, and such structural analogs between annelid and brachiopod setae support the homology of brachiopod and annelid setae, representing a lophotrochozoan synapomorphy. An alternative explanation involving attached macroalgae is proposed, given that branched setae have never been documented in either extinct or extant brachiopod taxa. If these structures represent macroalgae, this association could represent a mimicry strategy to deceive predators, although comparable macroalgal fossils remain undocumented in the Chengjiang Lagerstätte. Our research highlights the potential for brachiopod setae to serve roles in sensory function or ecological interactions, offering a new perspective on early animal adaptation and community dynamics. Full article

The flora of Haida Gwaii includes many macroalgal species, initially assumed endemic, which are largely absent from southern British Columbia but which were subsequently collected in California. One explanation for these disjunct distributions is the kelp conveyor hypothesis, which proposes non-buoyant macroalgae hitchhike on kelp rafts from central California to Haida Gwaii. Using mitochondrial COI-5P data, we adopt a weight-of-evidence approach and summarize broad patterns of allelic distribution and genetic differentiation across 11 species of red algae collected in California, Haida Gwaii and southern Vancouver Isl., British Columbia, to assess the impact of the kelp conveyor hypothesis. Although this hypothesis was based on species with disjunct distributions, we emphasize species with continuous distributions. In support of this hypothesis, we demonstrate low genetic differentiation between Haida Gwaii and California in 9 of 11 species consistent with significantly higher gene flow than from California to Vancouver Isl., and 13% of all alleles observed on Haida Gwaii were disjunct. These observations are consistent with predictions of the kelp conveyor hypothesis. Results here shed light on a previously cryptic source of gene flow which has impacted a considerable proportion of the red algal flora of Haida Gwaii. Full article

This study evaluated the performance of a recirculating aquaculture system (RAS) integrated with macroalgae (Ulva ohnoi) cultivation and sea urchin (Paracentrotus lividus) feeding, in a multi-trophic aquaculture approach. This system aimed to enhance sustainability through water bioremediation by macroalgae and valorization of the algal biomass as echinoderms feed. Over a 180-day trial, biomass production of U. ohnoi remained stable, with daily growth rates ranging from 7.4 to 24.4%. Statistical analyses (PCA and GAM) indicated no significant linear or non-linear relationship between macroalgae growth and environmental parameters (temperature, radiation, photoperiod). A theoretical estimate of nutrient production showed fairly stable values that do not statistically explain biomass production variation, highlighting the species’ adaptability. Sea urchins fed with fresh U. ohnoi showed regular growth, supporting the nutritional suitability of this macroalgae. For fish (Sparus aurata), no significant differences in growth or feed conversion ratio were observed between systems with and without algae. Parasitological monitoring revealed lower parasite loads and egg deposition in tanks in recirculation with U. ohnoi during certain periods, suggesting a potential role of macroalgae in reducing monogenean propagation. These findings underscore the feasibility of integrating Ulva cultivation into RAS, contributing to circular aquaculture models with improved sustainability and resource efficiency. Full article

Marine macroalgae, classified into three major groups, brown (Phaeophyceae), red (Rhodophyta), and green (Chlorophyta), represent a source of structurally diverse compounds relevant for topical applications. This narrative review of the peer-reviewed literature and regulatory databases targets macroalgae-derived active ingredients in cosmetic formulations and in wound-healing applications. It outlines major compound classes (polyphenols, sulfated polysaccharides, carotenoids, fatty acids, and peptides), along with their documented biological effects on skin (antioxidant, anti-inflammatory, moisturizing, photoprotective, and anti-aging activity) and regulatory/safety aspects with formulation strategies. This review also addresses the variability in compound concentrations resulting from species, environmental conditions, and seasonal factors, which impacts reproducibility and standardization. Common extraction techniques like solvent extraction, ultrasound-assisted extraction, supercritical fluid extraction, and enzyme-assisted methods are described in relation to compound class and yield. Analytical methods used for the identification and quantification of these compounds, including HPLC, GC-MS, and FTIR, are then summarized. Additionally, recent in vitro and in vivo studies evaluating the bioactivity and safety of macroalgae-derived ingredients are discussed. This review compiles relevant evidence to inform formulation strategies and ingredient evaluation in the context of marine-based topical products. Full article

Macroalgae are often used to produce sodium alginate, but their by-products have not been fully utilized. This study aimed to optimize the extraction of bound polyphenols (BPs) from Macrocystis pyrifera (L.) residues, analyze the composition of free polyphenols (FPs) and BPs, and evaluate their antioxidant activities and ability to inhibit glycosidase activity. The optimal conditions for extracting BPs achieved by the response surface method were as follows: 50 °C, a solid–liquid ratio of 1:50, an alkaline hydrolysis time of 2.38 h, and a NaOH concentration of 8 mol/L. Polyphenol content determination results indicated that FPs had significantly higher total polyphenols (13.02 ± 0.05 μg GAE/mg) and phlorotannin (3.44 ± 0.04 μg PE/mg) than BPs (6.57 ± 0.07 μg GAE/mg and 1.32 ± 0.20 μg PE/mg). HPLC/ESI-QTOF-MS showed distinct profiles: FPs had one polyhydroxy phenol, nine flavonoids, and four additional compounds, whereas BPs had five flavonoids and four other compounds. Antioxidant activity was found to be higher in FPs than in BPs (DPPH: 3.03 vs. 1.79 μg TE/mg; FRAP: 19.40 vs. 7.43 μg TE/mg). Furthermore, FPs exhibited 4.59- and 11-fold higher inhibition capacity toward α-amylase and α-glucosidase, respectively, compared to BPs. The results provide valuable basic data for the application of macroalgae residues in the marine biological industry and reveal their potential hypoglycemic ability. Full article