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Benefits of integrated shrimp/seaweed culture systems have been investigated; nevertheless, knowledge of the importance of microorganisms in the systems is limited. In the present study, we evaluated shrimp Litopenaeus vannamei under four experimental conditions: fed pelleted diet in the presence of Ulva lactuca with (UPE) and without water exchange (UPN) and fed only a pelleted diet with (PE) and without water exchange (PN). Bacterial communities present in shrimp, seaweed, and water were analyzed after 4 weeks of an experimental trial. Our results showed significantly lower shrimp final weight, weight gain, specific growth rate (SGR), and higher feed conversion ratio (FCR) with PN treatment compared to the rest of the treatments (P < 0.05). Seaweed resulted in lower relative abundance of Vibrio in the presence of shrimp (UPE and UPN) compared to monoculture (Ulv). Shrimp intestine presented lower Vibrio and significantly increased Sagittula and Lutimonas in treatments without water exchange. In the case of shrimp fed only pellet with water exchange (PE), a significantly higher relative abundance of Lucibacterium and Planctomicrobium genera was found compared to PN, UPE, and UPN treatments. The results suggest that the seaweed in a system with no water exchange is advantageous to promote water bacterial diversity, and that reduces the relative abundance of Vibrio in shrimp gut. Additionally, PERMANOVA analyses revealed that both seaweed presence and water exchange are significant factors in structuring the culture system microbiota (P < 0.001). The present study contributes to understanding the importance of microbial communities in shrimp/seaweed integrated aquaculture systems. [ABSTRACT FROM AUTHOR]

Species classified in the genus Ulva are important foundational marine primary producers distributed worldwide. These species are particularly abundant and diverse through the northwest Pacific (NWP) where they experience marked latitudinal gradients of environmental heterogeneity. It is unclear, however, to what extent such dynamic conditions can modulate phenotypic and genetic patterns in these organisms, potentially reflecting the influence of historical and contemporary biotic and abiotic factors. Here, we assessed inter- and intra-specific genetic patterns of Ulva species through the NWP using plastid rbcL and tufA gene sequences. Although we initially targeted Ulva australis based on morphological identification, we recovered eight Ulva genetic entities masked by morphological similarities. Except for the Ulva linza–procera–prolifera and U. lactuca–reticulata complexes, six of these genetic entities were recovered as individual species (i.e., U. australis, U. ohnoi, U. californica, U. compressa, U. lacinulata, and U. arasakii), and showed biogeographic patterns likely explained by clines in sea surface temperature and ocean current dispersal. At intra-specific level, all the genetic entities showed low genetic variation and divergence based on rbcL (0–0.3 %) and tuf A (0–0.9 %) data. Our results provide insights regarding intra- and inter-specific genetic patterns characterizing morphologically similar Ulva species through the NWP. However, further studies are needed to understand the mechanisms underpinning such patterns and the associated ecological and evolutionary implications. [ABSTRACT FROM AUTHOR]

DNA sequences were obtained from 32 blade-forming Ulva specimens collected in 2018 and 2019 from four islands in the Galápagos Archipelago: Fernandina, Floreana, Isabela and San Cristóbal. The loci sequenced were nuclear encoded ITS and plastid encoded rbcL and tufA, all recognized as barcode markers for green algae. Four species were found, Ulva adhaerens, U. lactuca, U. ohnoi and U. tanneri, all of which have had their type specimens sequenced, ensuring the correct application of these names. Only one of these, U. lactuca, was reported historically from the archipelago. Ulva adhaerens was the species most commonly collected and widely distributed, occurring on all four islands. Previously known only from Japan and Korea, this is the first report of U. adhaerens from the southeast Pacific Ocean. Ulva ohnoi was collected on three islands, Isabela, Floreana, and San Cristóbal, and U. lactuca only on the last two. Ulva tanneri is a diminutive, 1–2 cm tall, high intertidal species that is easily overlooked, but likely far more common than the one specimen that was collected. This study of blade-forming Ulva species confirms that a concerted effort, using DNA sequencing, is needed to document the seaweed flora of the Galápagos Archipelago. [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]

During the cultivation of Ulva fenestrata in a land-based aquaculture system, the colonisation of the water tanks' surfaces and eventually the macroalgal biomass by the biofouling diatom Fragilariopsis oceanica compromises the production process. Since germanium dioxide (GeO2) is an effective growth inhibitor of diatoms, this study aimed to understand how it affects the presence of F. oceanica and the photosynthesis and growth of U. fenestrata as a primary parameter contribution to the biomass production. A toxicological dose-response experiment showed that the diatom's growth was inhibited at the low GeO2 concentration of 0.014 mg l−1. In contrast, the photosynthetic performances and growth rates of U. fenestrata remained unaffected under a wide GeO2 concentration range (0.022–2.235 mg l−1) in small- and large-scale experiments in 1-l glass beakers and 100-l Plexiglass water tanks, respectively. In the latter, the diatom density in the tanks was reduced by 40 %. The costs arising from the use of GeO2 can range between €2.35 and €8.35 kg−1 fresh weight of produced U. fenestrata biomass under growth conditions resulting in growth rates of 20 and 11.5 % d−1, respectively. GeO2 is an effective agent to control biofouling diatoms such as F. oceanica during the land-based biomass production of U. fenestrata. [ABSTRACT FROM AUTHOR]

The 2007 flora "Green Seaweeds of Britain and Ireland" did not present the molecular data underpinning the Ulvaceae treatment, mostly ITS sequences. Subsequently, names have changed as type material of Ulva species is sequenced and intensive sampling with DNA barcoding adds new European species. To update the Ulvaceae, we systematically sampled from 2007 to 2021, identifying specimens using various molecular markers alongside DNA from type material of four species. We show here that Ulva gigantea, based on rbcL, tufA and ITS sequences of its holotype, is assigned to Ulva compressa, as is the lectotype of Ulva curvata. Ulva gigantea sensu GenBank and Ulva pseudocurvata are conspecific. The correct name is U. pseudocurvata based on rbcL sequences of the lectotype. Two species of monostromatic Ulvaceae were included in the 2007 flora, but we show that both of them and all earlier British monostromatic collections represent Ulvaria splendens, a species originally described from Alaska. Analysis of two rbcL amplicons of the Ulva sordida lectotype shows that it is conspecific with Ulvaria splendens. Our first genuine collections of Ulvaria obscura from SW England and SW Wales correspond to topotype material from the Bay of Biscay, recent samples from Galicia and unpublished tufA sequences from Britanny. [ABSTRACT FROM AUTHOR]

Axenic cultures of the green seaweed Ulva mutabilis were inoculated with bacteria providing essential algal growth and morphogenesis-promoting factors (AGMPFs) and were exposed to temperature shifts from 18 °C to 30 °C. The temperature-dependent effect of bacteria on longitudinal algal growth and the molecular composition of the chemosphere in the algal culture medium was explored. The reductionist tripartite model system of U. mutabilis, Roseovarius sp. MS2, and Maribacter sp. MS6 was applied as a reference and has been changed by substituting Roseovarius with isolates that phenocopy this strain. Rathayibacter festucae IH2 and Roseovarius aestuarii G8 boosted growth at 18 °C but slowed it down at 30 °C. Additional inoculation of Roseovarius sp. MS2 mitigated these adverse bacterial effects partially. At 30 °C, the molecular profile of the chemosphere differed dramatically between all tested tripartite communities, indicating different traits of the same bacterium with changing temperatures. Functional examinations should, therefore, accompany microbiome analysis to detect changing traits with the same microbiome composition. [ABSTRACT FROM AUTHOR]

Misapplication of Ulva epithets in GenBank has led to confusion in the scientific literature and community. To solve some of the problems, targeted DNA sequencing of plastid encoded rbcL gene amplicons or high-throughput sequencing was performed on all blade-forming Ulva type specimens from the northeast Pacific. Recently collected specimens from at or near type localities were also analyzed for some taxa. Based on these genetic analyses, we confirmed currently recognized species: U. californica, with U. angusta and U. scagelii as heterotypic synonyms, U. stenophylla, U. taeniata, and U. tanneri. Ulva dactylifera, currently considered a synonym of U. taeniata based on morpho-anatomy, is recognized as a distinct species, as is U. expansa whose type specimen was sequenced in 2018. All but two of the ITS, rbcL and tufA sequences in GenBank that were labeled U. californica were correctly named, in contrast to U. taeniata, for which only one of 14 sequences was correctly labeled. These results show that DNA sequencing of Ulva type specimens is essential for the correct application of names. [ABSTRACT FROM AUTHOR]

The use of high-value fatty acids (FA), omega-3 (n-3), and omega-6 (n-6) from seaweed could relieve the pressure from natural wild fish sources and reduce overfishing worldwide. This research is designed to explore how the harvest season (winter, spring, and summer) and culture period influence the biomass production yield, lipid content, and FA composition in the green seaweed Ulva sp. The studied seaweed was grown in plastic sleeves with flowthrough seawater in Mikhmoret (East Mediterranean, Israel) from July 2019 to December 2020. The Ulva species was identified as Ulva lactuca Linnaeus by DNA barcoding using rbcL, ITS, and tufA markers. No detectable genetic variability in U. lactuca samples was found throughout the research period. A quantitative examination of the lipid and FA content in U. lactuca in different harvest seasons revealed that the maximum content of lipids was in the summer, and that of polyunsaturated fatty acids (PUFAs) was in the winter. The PUFA profile included eicosapentaenoic acid, docosapentaenoic acid, docosahexaenoic acid, n-3, and n-6, where the n-6/n-3 ratio was comparable with the desired range for a balanced nutritional diet. [ABSTRACT FROM AUTHOR]

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]

When emersed, intertidal seaweeds experience rapid changes in environmental conditions. On warm sunny days, seaweeds can desiccate soon after emersion. On rainy days or in areas with freshwater inputs, they may experience rapid drops in salinity. To determine whether one low tide's exposure to environmental stress alters seaweed growth, palatability to herbivores, and dimethylsulfoniopropionate (DMSP) concentrations, we exposed Ulva fenestrata to desiccation and hyposaline conditions for 3 h in summer and winter. Two days later, summer desiccation decreased growth, consumption by Lacuna vincta, and DMSP by 71%, 83%, and 67%, relative to controls. Winter desiccation reduced DMSP by 19% and did not affect growth or L. vincta feeding. Summer hyposaline conditions increased growth by 75% but did not affect L. vincta grazing or DMSP, whereas winter hyposaline conditions reduced growth by 37%. After 2 days of exposure to L. vincta, seaweeds were allowed to recover for 7 days, then DMSP was measured. U. fenestrata desiccated in the summer did not survive. Average DMSP concentrations were 127% higher in grazed than ungrazed seaweed in the summer salinity experiment, providing evidence that grazing induces DMSP. No DMSP induction occurred in winter, possibly because grazing rates were much lower. In a follow-up summer desiccation experiment, maximum quantum yields (MQYs) and DMSP decreased to 12% and 14% of controls within an hour. After 7 days, MQY and DMSP concentrations recovered, but growth was 81–97% lower in seaweeds desiccated for 30–60 min, relative to controls. These results provide the first evidence for grazer-induced DMSP increases. [ABSTRACT FROM AUTHOR]

Edible green algal species are the most widely distributed and diverse macroalgae in the world and are considered as an important source of bioactive molecules which serve as multi-product sources for nutritional and pharmaceutical applications. The present investigations were carried out concerning biochemical constituents from three species of green marine algae Ulva conglobata, Caulerpa racemosa, and Bryopsis plumosa collected from the coast of Veraval Chowpati, Gujarat India. The biochemical composition was analysed using uv-spectrophotometer to evaluate its food value and find out variations in composition during the investigation period. The reducing sugar, proline, and starch contents were high in Bryopsis plumosa followed by Caule rpa racemosa and Ulva conglobata. Proline content is higher than the total amino acids in three algal species. The protein contents following by Lowry method Caulerpa racemosa have a high amount with 1667.32 ± 18.42 (µgg-1 dry wt.) followed by Bryopsis plumosa 1394.98 ± 18.78 (µgg-1 dry wt.) and Ulva conglobata 292.72 ± 17.85 (µgg-1 dry wt.). The protein content was recorded maximum in Bryopsis plusmosa and Caulerpa racemosa than in the Ulva conglobata. All the assays carried out in the present work showed that all selected green algae are good sources of biochemical. According to the biochemical composition values of the studied algae, they have the potential to be a source of constituents with high nutritional value and use in the food, dietary, and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

Annual outbreaks of floating Ulva prolifera blooms in the Yellow Sea have caused serious local environmental and economic problems. Rapid and effective monitoring of Ulva blooms from satellite observations with wide spatial-temporal coverage can greatly enhance disaster response efforts. Various satellite sensors and remote sensing methods have been employed for Ulva detection, yet automatic and rapid Ulva detection remains challenging mainly due to complex observation scenarios present in different satellite images, and even within a single satellite image. Here, a reliable and fully automatic method was proposed for the rapid extraction of Ulva features using the Tasseled-Cap Greenness (TCG) index from satellite top-of-atmosphere reflectance (RTOA) data. Based on the TCG characteristics of Ulva and Ulva-free targets, a local adaptive threshold (LAT) approach was utilized to automatically select a TCG threshold for moving pixel windows. When tested on HY1C/D-Coastal Zone Imager (CZI) images, the proposed method, termed the TCG-LAT method, achieved over 95% Ulva detection accuracy though cross-comparison with the TCG and VBFAH indexes with a visually determined threshold. It exhibited robust performance even against complex water backgrounds and under non-optimal observing conditions with sun glint and cloud cover. The TCG-LAT method was further applied to multiple HY1C/D-CZI images for automatic Ulva bloom monitoring in the Yellow Sea in 2023. Moreover, promising results were obtained by applying the TCG-LAT method to multiple optical satellite sensors, including GF-Wide Field View Camera (GF-WFV), HJ-Charge Coupled Device (HJ-CCD), Sentinel2B-Multispectral Imager (S2B-MSI), and the Geostationary Ocean Color Imager (GOCI-II). The TCG-LAT method is poised for integration into operational systems for disaster monitoring to enable the rapid monitoring of Ulva blooms in nearshore waters, facilitated by the availability of near-real-time satellite images. [ABSTRACT FROM AUTHOR]

Ulva prolifera (U. prolifera) green tide outbreaks have occurred in the Yellow Sea of China for many years, causing serious losses to marine ecology and the marine economy. The monitoring and tracking of U. prolifera green tide is a crucial aspect of marine ecological disaster prevention and control management. This paper aims to investigate the spatiotemporal distribution changes in U. prolifera green tide in the Yellow Sea throughout its life cycle. A survey of the Yellow Sea from 2008 to 2023 was conducted using multi-source remote sensing images. Long-term monitoring and analysis of U. prolifera revealed the evolution process of the green tide, including the early development, outbreak, decline, and extinction stages, considering time, space, and frequency of occurrence. Additionally, this study examined peak coverage change patterns over the past 16 years and analyzed the influence of environmental factors such as sea surface temperature and sea surface wind field on the development of U. prolifera. The research results serve as a valuable reference for the monitoring, early warning, and scientific prevention and control of U. prolifera green tide in the Yellow Sea, as well as other similar marine disaster areas. [ABSTRACT FROM AUTHOR]

Ulva, an edible green alga, contains sulfated polysaccharides and oligosaccharides that possess immunomodulatory and anti-inflammatory properties. The objective of this study was to investigate the anti-allergic effects of Ulva-derived samples of polysaccharides (UP), oligosaccharides (UO), and residues (UR) on delayed-type hypersensitivity (DTH) in mice. Oral treatment of mice with UP, UO, and UR (250 mg/kg body weight) daily noticeably improved the DTH reaction as evidenced by attenuation of footpad swelling and cell infiltration at the allergen-challenge site. Although the Ulva samples had limited impacts on the production of serum total IgG, decreased concentrations of allergen-specific IgG and IgG2a and an increased concentration of IgG1 were observed in the treated mice. Moreover, treatment with them suppressed allergen-induced IFN-γ and TNF-α secretion and elevated IL-4 secretion. However, none of the Ulva sample treatments could modulate the production of IL-10. Concordantly, the in situ data reveal that the Ulva sample treatments suppressed IFN-γ and TNF-α expression at the allergen-injection site. These findings collectively suggest the potential of UP, UO, and UR as functional food candidates for the management of delayed-type hypersensitivity. [ABSTRACT FROM AUTHOR]

A fully enantioselective, catalytic synthesis of the algal morphogen (−)‐thallusin using polyene cyclization chemistry is reported. The synthesis features dedicated precursor design, introduction of a TMS‐substituted arene as a regioselective terminator, very high enantiomer excess (ee) on gram scale, and productive scaffold functionalization. Furthermore, an ee determination methodology of thallusin samples was developed, and the ee of biosynthesized thallusin was determined. Fe(III)‐uptake studies demonstrated that the cellular uptake of iron facilitated by thallusin derivatives was independent of their morphogenic activity, suggesting their active import via siderophore transporters as a shuttle system. [ABSTRACT FROM AUTHOR]

This study focused on evaluating the effect of different concentrations of nutrients and total suspended solids on the removal rate of nutrients and biocompounds from the macroalgae U. lactuca in an integrated system with the shrimp Penaeus vannamei in biofloc. The experiment lasted 45 days and included five treatments with three replicates each, with percentages of 0 (control), 25, 50, 75, and 100% biofloc inoculum (73.3 ± 5.7 and 325.0 ± 21.2 mg L−1 initial nitrate and solids, respectively, in the 100% inoculum), from a shrimp farm, resulting in different concentrations of solids and nutrients. The macroalgae were introduced into 280 L tanks at a density of 0.88 kg m−2, along with 200 shrimp m−3. The algae were separated by a floating structure. Water quality parameters were measured, and the nutrient removal rate was evaluated. The treatment with 75% inoculum showed a removal rate of 55.0 ± 4.0 and 31.0 ± 10.0% of nitrate and phosphate, respectively. There was no difference in macroalgae growth between the treatments; however, macroalgae grown in 75% inoculum had higher protein, chlorophyll-a, and lower ash values compared with the control. The use of macroalgae in integrated production with shrimp under the conditions of the treatment with 75% biofloc inoculum proved to be viable and sustainable. [ABSTRACT FROM AUTHOR]

In this work, the properties of biochar produced from green macroalga Ulva intestinalis by pyrolysis were studied at temperatures of 300, 500, and 700 °C. This biochar was characterized in terms of multielemental composition, BET surface area, total pore volume, and biosorption properties toward phosphate ions. Biochar produced at 700 °C–25 m2/g had the highest surface area. The kinetics and isotherms of sorption processes of phosphate ions as sorbate by these sorbents were investigated. Modified biochar was able to remove 84.3% of phosphate ions from wastewater, whereas non-modified biochar—only 40.6%. Hence, biochar enriched with phosphate ions can serve as a valuable soil amendment. Pot experiments performed on winter wheat (Triticum aestivum) with a 3% addition of dry Ulva intestinalis, pristine biochar, and Mg-modified biochar enriched with phosphate ions showed that these amendments stimulated plant growth (length and fresh weight of plants) as well as enlarging the chlorophyll content in leaves. Our results indicate that the production of biochar (pristine and Mg-impregnated) is a sustainable option to valorize the biomass of seaweeds, and to recycle phosphorus from wastewater. [ABSTRACT FROM AUTHOR]

This study exploits the potential of satellite remote sensing reflectance spectra (Rrs(λ)) for detecting ocean surface algal blooms. Three types of floating surface algae are examined: Sargassum, Ulva, and Trichodesmium. The satellite images are processed with a shortwave infrared (SWIR)-based atmospheric correction processor from the Visible Infrared Imaging Radiometer Suite (VIIRS). We calculate the red-edge reflectance anomaly from the Rrs(λ) data to delineate the notable spectral difference at 671 and 862 nm. The new data have generated floating algal maps comparable with historical methods relying on Rayleigh-corrected reflectance data. The Rrs(λ) spectra are found to have high quality scores over Sargassum and Trichodesmium waters, suggesting less uncertainty from atmospheric correction. With problems to be addressed, this preliminary study finds it promising to use the VIIRS reflectance products for floating algae detection and mapping. Continuous efforts are highly recommended as the new data and approach can not only facilitate a retrospective analysis over global oceans but also benefit a greater application to next-generation hyperspectral satellites.

Green macroalgae (Ulva sp.) and red macroalgae (Solieria sp.) were processed to produce eight different crude extracts enriched for marine sulphated polysaccharides (MSP). While all extracts showed direct anti-bacterial effects to some degree, two red algal extracts, in particular, showed high activity against several pathogenic fish bacteria in vitro. Stimulation of head kidney leukocytes (HKLs) in vitro with MSP-rich extracts showed fish species specific differences. In Nile tilapia, HKLs showed a dose dependent production of reactive oxygen species (ROS) following stimulation with Ulva-derived extracts, while stimulation with Solieria-derived extracts did not induce ROS production. In rainbow trout, HKLs showed relatively high reactive ROS potential and Solieria-derived extracts could induce significant ROS production, albeit without a clear dose dependent response. Gene expression of in vitro stimulated HKLs showed a clear induction of most cytokines measured (il1b, il10, tnfa, ifny, il12p40), with differences between species. Although cytokine gene expressions were more prominently induced in HKLs of Nile tilapia than in HKLs of rainbow trout, immunomodulatory effects of both, Ulva- and Solieria-derived extracts, always appeared evident. It is likely that HKLs have the ability to sense presence of MSP, via so far uncharacterized pattern recognition receptors which have known downstream signalling pathways. Expression of some genes associated with Toll-like Receptor (TLR) signalling, such as irak1 and especially the expression of genes associated with C-type Lectin Receptor (CLR) signalling, such as card9 and bcl10 were evident following stimulation with MSP-rich extracts. Possibly, immunomodulatory effects of MSP could be regulated by at least a CLR-mediated signalling, at least in Nile tilapia, for which most if not all red algae and green algae extracts induced changes in gene expression of card9 and bcl10. Overall, induction of ROS production and gene expression read-outs suggest immunomodulatory effects of MSP-rich extracts derived from green algae (Ulva sp.) and red algae (Solieria sp.), at least in vitro. The observed effects suggest clear fish species specific differences between the effects of MSP-rich extracts.

ABSTRACTMacroalgal biomass production models that capture nutrient dynamics, temperature, light and salinity are important for the design and operation of large-scale farms. The goal of this study is to understand how the nitrogen fertilizing regime, relating to dose (µM N week−1), amplitude (µM N) and duration (hours) of fertilization, affects the dynamics of nitrogen content and biomass production of Ulva sp. We hypothesize that the nitrogen fertilizing regime controls the Ulva Nitrogen Use Efficiency (NUE), defined here as the fraction of fertilizer nitrogen that is utilized and allocated to yield N, and, accordingly, also nitrogen assimilation in the biomass and the growth rate. We test this hypothesis by measuring internal nitrogen and biomass weight and by calculating NUE under various fertilization regimes in controlled photobioreactors. Based on these experimental data, we developed a biomass productivity model that predicts nitrogen and biomass dynamics temporally over three weeks of cultivation. This study highlights efficient fertilizing regimes and enables the development of a comprehensive understanding of the dynamic relationship between external N, internal N and biomass production of Ulva sp. under varying external N levels, which is important for real-world agricultural applications. This study provides a better understanding of the external N-internal N-biomass triangle leading to an improved dynamic cultivation model, enabling better control of nutrient application and biomass production in macroalgal farming for a sustainable marine bioeconomy.

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]

Seaweeds, including the green Ulva lactuca, can potentially reduce competition between feed, food, and fuel. They can also contribute to the improved development of weaned piglets. However, their indigestible polysaccharides of the cell wall pose a challenge. This can be addressed through carbohydrase supplementation, such as the recombinant ulvan lyase. The objective of our study was to assess the muscle metabolism of weaned piglets fed with 7% U. lactuca and 0.01% ulvan lyase supplementation, using an integrated transcriptomics (RNA-seq) and proteomics (LC–MS) approach. Feeding piglets with seaweed and enzyme supplementation resulted in reduced macronutrient availability, leading to protein degradation through the proteasome (PSMD2), with resulting amino acids being utilized as an energy source (GOT2, IDH3B). Moreover, mineral element accumulation may have contributed to increased oxidative stress, evident from elevated levels of antioxidant proteins like catalase, as a response to maintaining tissue homeostasis. The upregulation of the gene AQP7, associated with the osmotic stress response, further supports these findings. Consequently, an increase in chaperone activity, including HSP90, was required to repair damaged proteins. Our results suggest that enzymatic supplementation may exacerbate the effects observed from feeding U. lactuca alone, potentially due to side effects of cell wall degradation during digestion. [ABSTRACT FROM AUTHOR]

Ulee Lheue Beach in Banda Aceh was developed for tourism. The macroalgae and seaweed species found in this area have been widespread but never exploited. Among these species is the green seaweed, Ulva lactuca, commonly known as sea lettuce. The physiological variations and genetic features of the seaweed can be attributed to the variations in the coastal environment. This study aims to describe the molecular identity of the genetic diversity of U. lactuca from the intertidal zone at Ulee Lheue Beach. The development of molecular biotechnology has enabled identification the gene expression through genomic DNA to PCR amplification. Genetic distance was determined using UPGMA. The results from 600-bp fragments were analyze the genetic diversity. A total of 15 (31%) expression identified as polymorphic (>0.500). Heterozygosity (He) and allelic differential (Na) diversity were found of 1.500-3.000. The highest PIC was observed in the rbcL1, with a correlation between subpopulations of 0.459. PCR amplification using the degenerate primer rbcL1 produced fragments ranging from 300 to 460 bp, whereas the expression of UL2 was detected at 448 and 500 bp using the rbcL2 primer. The phylogenetic identify are shown two (2) clusters. The populations of UL1, UL3, and UL4 were found a close relationship. Furthermore, the UL1 and UL2 populations were further divided into distinct clusters but related to the main branch of UL3. Based on this research, the concern of U. lactuca species for industrial and biotechnology destinations, we can describe a suitable method for obtaining he genetic distances between species. [ABSTRACT FROM AUTHOR]

This study investigates the potential utility of Ulva fasciata biomass for biohydrogen production and its disintegration under ultrasonic disintegration (UD), and ultrasonic combined surfactant disintegration (UCSD). SCOD release and specific energy consumption were evaluated for UD and UCSD. In UCSD, optimal surfactant addition was 10 μl, 160 W sonication power, and 30-min sonication time resulted in a maximum release of SCOD of 1030 mg/L and a maximum solubilization of 21.2% to compare the performance of UD and UCSD, biopolymer release was analyzed. The maximum protein and carbohydrate release was 680 mg/L and 224.2 mg/L the disintegrated substrate was evaluated for its biohydrogen production under anaerobic conditions with both UD and UCSD. As compared to UD (90.4 mL), and control (17.3 mL), UCSD (121.6 mL) produced more biohydrogen. According to its energy analysis, UCSD had a positive net energy of 0.012 kW h/kg and an energy ratio of 1.375. This study also reveals that macroalgae U. fasciata could be a sustainable renewable energy source for biohydrogen production. • Biohydrogen production from Ulva fasciata, a macroalgal source. • A higher biomass liquefaction of 21.2% was found in combined pretreatment. • Surfactant-mediated pretreatment significantly improves biohydrogen production. • Net energy of combined pretreatment is higher than ultrasonic alone. [ABSTRACT FROM AUTHOR]

Macroalgal growth and yield are key to sustainable aquaculture. Although light and water turbulence are two important factors that affect algal productivity, research on their interaction is limited. Therefore, in this study, we investigated the effects of different wavelengths of light and the presence or absence of water turbulence on the growth of the green macroalga Ulva australis. Water turbulence was found to enhance the growth of U. australis irrespective of photosynthetic performance, but only in blue light cultures. The quantum dose of blue light required to induce 50% growth promotion was 1.02 mol m−2, which is comparable to the reported values for cryptochrome-mediated effects in other macroalgae. The combined effect of blue light and water turbulence led to the accumulation of photosynthesis-related proteins that support plastid differentiation and facilitate efficient photosynthesis and growth. Our findings thus highlight the potential of harnessing blue light and water turbulence to maximise macroalgal cultivation for sustainable and profitable algal aquaculture. [ABSTRACT FROM AUTHOR]

The objective of the current investigation was to assess the hepatoprotective capabilities of two algal species, Ulva lactuca and Spirulina platensis, in carp (Cyprinus carpio) fingerlings subjected to imazalil exposure. Consequently, the experimental groups were simultaneously exposed to the fungicide (5mg/kg feed) and provided with feed containing either Ulva lactuca alone (IMZ-Uv variants - 5 g/kg ulva), Spirulina platensis alone (IMZ-Sp variants - 5 g/kg spirulina), or a combination of both algae (IMZ-Uv-Sp variants - 2.5 g/kg ulva and 2.5 g/kg spirulina). Two control variants were employed in the experiments: a negative control receiving normal feed and a positive control receiving feed with 5mg/kg imazalil. Each variant involved 15 fish per tank, and after the experiment, five fish from each tank were utilized for biological samples. The assessment of biochemical serum parameters and oxidative stress markers for each specimen revealed that imazalil induced alterations in biochemical parameters, resulting in physiological dysfunctions in carp. However, the administration of algae, in particular Spirulina platensis, demonstrated significant potential in mitigating the adverse effects of imazalil. [ABSTRACT FROM AUTHOR]

Acetaminophen (AAP) is an analgesic–antipyretic drug which is considered safe at recommended dose, but its overuse may induce renal and hepatic injuries. Marine macro algae have great potential against drug-induced renal and hepatic dysfunctions. The present study described the reno-protective and hepato-protective effects of the ethanol extract of an edible green alga Ulva fasciata and its fractions (n-hexane, chloroform and methanol) against AAP toxicity. In the 1st set of experiment, rats were divided into five groups. Of which two were treatment groups beside three controls, the first treatment group was given ethanol extract of U. fasciata alone and the second group was given the same extract with AAP. In the 2nd set of experiment, rats were divided into nine groups, of which three treatment groups administered n-hexane, chloroform and methanol fractions of ethanol extract of U. fasciata respectively while other three treatment groups received the same fractions individually with AAP. On the 11th day, rats were decapitated after 12 h of fasting from both sets, blood samples were collected for assessment of biochemical parameters and kidney tissues were used for determination of oxidants and antioxidants. Histopathological assessment was also done in kidney tissues. A single dose of AAP (600 mg/kg) affected kidney markers including creatinine, urea and blood urea nitrogen (BUN) and hepatic enzymes. Ethanolic extract of U. fasciata normalized kidney and liver markers in AAP intoxicated rats. AAP also reduced glutathione (GSH) in kidney tissues and altered kidney architecture, which were improved by ethanolic extract and chloroform soluble fraction of U. fasciata. A total of 14 polyunsaturated fatty acids were identified from chloroform soluble fraction of U. fasciata by GC-MS and assumed these may be involved in protective activities of U. fasciata. [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]

A novel inland record of the green alga Ulva intestinalis was found in central Kamchatka, in a brackish stream originating from cooled waters of drilled thermal springs. This species was observed in May 2017, but not encountered again at the same site despite targeted search. Its occurrence in central Kamchatka was surprising given the natural environment, and was probably related to both the presence of thermal springs and human disturbance. The sporadic inland appearance of U. intestinalis in this region suggests it may be unable to maintain stable populations in this region, and experience repeated local extinctions and recolonizations. [ABSTRACT FROM AUTHOR]

Background and Aim: Global efforts are continuing to develop preparations against cryptosporidiosis. This study aimed to investigate the efficacy of biosynthesized Ulva fasciata loading Cinnamomum camphora oil extract on new zinc oxide nanoparticles (ZnONPs shorten to ZnNPs) and silver nanoparticles (AgNPs) as alternative treatments for Cryptosporidium parvum experimental infection in rats. Materials and Methods: Oil extract was characterized by gas chromatography-mass spectrometry, loaded by U. fasciata on ionic-based ZnO and NPs, and then characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. Biosafety and toxicity were investigated by skin tests. A total of 105 C. parvum oocysts/rat were used (n = 81, 2-3 W, 80-120 g, 9 male rats/group). Oocysts shedding was counted for 21 d. Doses of each preparation in addition to reference drug were administered daily for 7 d, starting on post-infection (PI) day (3). Nitazoxanide (100 mg) was used as the reference drug. After 3 weeks, the rats were sacrificed for postmortem examination and histopathological examination. Two blood samples/rat/group were collected on the 21st day. Ethylenediaminetetraacetic acid blood samples were also used for analysis of biochemistry, hematology, immunology, micronucleus prevalence, and chromosomal abnormalities. Results: C. camphora leaves yielded 28.5 ± 0.3 g/kg oil and 20 phycocompounds were identified. Spherical and rodshaped particles were detected at 10.47-30.98 nm and 18.83-38.39 nm, respectively. ZnNPs showed the earliest anticryptosporidiosis effect during 7-17 d PI. Other hematological, biochemical, immunological, histological, and genotoxicity parameters were significantly fruitful; hence, normalized pathological changes induced by infestation were observed in the NPs treatments groups against the infestation-free and Nitazoxanide treated group. Conclusion: C. camphora, U. fasciata, ZnNPs, and AgNPs have refluxed the pathological effects of infection as well as positively improved host physiological condition by its anticryptosporidial immunostimulant regenerative effects with sufficient ecofriendly properties to be proposed as an alternative to traditional drugs, especially in individuals with medical reactions against chemical commercial drugs. [ABSTRACT FROM AUTHOR]

The concept of floating algae index (FAI), a measure of the red-edge reflectance of floating vegetation, has been used to map floating macroalgae in global oceans. However, when the algae mats are submerged in water due to winds and other factors, the reduced reflectance (and thus reduced FAI value) is interpreted as being caused by reduced areal density (or biomass density) of algae, leading to underestimated algae amount. Here, a depth invariant FAI is proposed to overcome this difficulty. The depth invariant FAI is formulated using three spectral bands whose selective water attenuations can compensate for the reduced reflectance, resulting in FAI values that are nearly independent of the submerged depth of up to 30 cm with underestimates of the algae amount reduced from >50% to a few percent. In this study, the concept of depth invariant FAI is demonstrated through simulations only. With the new Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission and other hyperspectral satellite missions in the near future, such a concept is expected to be tested and evaluated with satellite data, from which the optimal bands can be selected to reduce uncertainties in mapping floating macroalgae. [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]

Ulva prolifera (U. prolifera), a global eco-environmental issue, has been recurring annually in the Yellow Sea of China since 2007, leading to significant impacts on the coastal ecosystem and the economies of coastal cities. To enhance the frequency of daily monitoring for U. prolifera and to advance the multi-source remote sensing monitoring system, a combination of the Sentinel-1 SAR remote sensing satellite and the Sentinel-3 OLCI and NPP VIIRS optical remote sensing satellites was employed. This comprehensive analysis encompassed the examination of Sentinel-1 C band characteristics, the range of influence of U. prolifera, and the migration trajectory of its enrichment zones. On 6 June 2021, three satellite images depicted the northwest drift of U. prolifera, followed by a southward movement after making contact with the coast of Qingdao, China, on 12 June. The most extensive impact area caused by U. prolifera was observed on 18 June. Subsequently, the images revealed a contraction and enrichment of U. prolifera in an eas–-west direction. The amalgamation of radar and optical remote sensing satellites in a multi-frequency monitoring approach allows for a continuous all-weather surveillance mechanism for U. prolifera. This mechanism serves to provide timely alerts for the prevention and management of U. prolifera outbreaks. [ABSTRACT FROM AUTHOR]

Simple Summary: With the aggravation of water eutrophication and global climate change, macroalgal blooms along coastal areas worldwide have become increasingly common in recent years. As the largest green macroalgal bloom, in the Yellow Sea of China we can observe that environmental stress caused by the overgrowth and degradation of Ulva prolifera has a harmful effect on marine organisms and the aquaculture industry. Therefore, exploring the harmful effect of Ulva prolifera stress on fish could promote the development of aquaculture in the Yellow Sea. This study revealed that Ulva prolifera stress suppressed antioxidant capacity in the liver and induced an inflammatory response accompanied by the activation of endoplasmic reticulum stress in the head kidney of the Japanese flounder, which could lead to huge damage to fish health. As the largest green macroalgal bloom in the Yellow Sea of China, the overgrowth and degradation of Ulva prolifera (U. prolifera) have a harmful effect on marine organisms and the aquaculture industry. However, the regulation mechanism of U. prolifera stress on the antioxidant capacity and inflammatory response of marine fish is still not completely understood. A 15-day exposure experiment was conducted to evaluate the effects of U. prolifera stress on the antioxidant capacity and inflammatory response of the Japanese flounder (Paralichthys olivaceus) (283.11 ± 6.45 g). The results showed that U. prolifera stress significantly decreased their survival rate. Serum total antioxidant capacity (T-AOC) and non-specific immune-related enzyme activities were significantly impacted under U. prolifera conditions. Moreover, U. prolifera stress significantly decreased T-AOC, superoxide dismutase (SOD) activity, and catalase (CAT) activities in the liver, while malondialdehyde (MDA) contents were significantly increased. Similarly, antioxidant-related gene (cat, nrf2, and keap1) expressions were synchronously downregulated in the liver under U. prolifera stress. Furthermore, U. prolifera stress significantly upregulated pro-inflammatory gene (tnf-α, il-1β, ifn-γ, and p65) expressions and the phosphorylation levels of the p38 and JNK MAPK pathways in the head kidney. In addition, endoplasmic reticulum (ER) stress-related gene and protein expressions were also upregulated in the head kidney. Overall, these results revealed that U. prolifera stress suppressed the antioxidant capacity and induced an inflammatory response in the Japanese flounder. This study could advance the understanding of the adverse effects of U. prolifera stress on marine benthic fish and promote the sustainable development of aquaculture. [ABSTRACT FROM AUTHOR]

Green algae are a sustainable source of biopolymers for the global demand due to their high photosynthetic efficiency. This article describes the extraction of cellulose from plant systems represented by Ulva lactuca species. In order to extract various substances, algae were finely ground with the help of solvents (liquid media). This was carried out to achieve the necessary conditions that help reduce the resistance this phase shows in regard to the transport and transfer of the species being extracted. The highest yield of extracted cellulose (20,944%) was obtained for the following factors: S/L = 1/20; conc. ethanol = 90%, conc. salts = 4 g/L. Hydrogel membranes are a unique class of macromolecular networks that contain a large fraction of aqueous solvent within their structure. With the cellulose extracted from algae, we obtained membranes which underwent the process of swelling in liquid media (ethyl alcohol) of different concentrations. The swelling of biocellulose membranes in alcoholic solutions of high concentrations was investigated. It was observed that the process of absorption of the alcoholic solution by the membrane occurred rapidly in the first part. After stabilization, the membranes continued to absorb at a slower rate until stabilization or saturation concentration was reached. [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]

Massive macroalgae blooms, primarily caused by the overgrowth of Ulva prolifera (U. prolifera) in the Yellow Sea of China, pose a severe risk to both marine organisms and the aquaculture industry. This study's aim was to evaluate the impact of U. prolifera degradation on the growth performance and antioxidant capacity of Japanese flounder (Paralichthys olivaceus) and select some potential Japanese flounder families (labeled 2101–2108, established by crossbreeding) tolerating U. prolifera degradation conditions. Thus, a 60-day U. prolifera exposure experiment was conducted. The results showed that the contents of Na, K, Mg, and Fe elements in the U. prolifera degradation water were significantly increased. The specific growth rate and survival rate of flounder were significantly decreased under the U. prolifera degradation condition, while the 2101 and 2103 flounder families showed a better growth performance compared with the positive control (PC) group. Moreover, the results showed that activities of total antioxidant capacity (T-AOC), transaminases, and alkaline phosphatase (AKP) in serum were significantly decreased, while the 2103 flounder family showed higher activities. Furthermore, U. prolifera degradation significantly increased superoxide dismutase (SOD) activity and glutathione (GSH) content while decreasing catalase (CAT) activity and malondialdehyde (MDA) content in the liver. Specifically, SOD and CAT activities of the 2103 flounder family were higher than the 2101 flounder family and PC group. In addition, the gill SOD and CAT activities of the 2103 flounder family were significantly higher than the PC group. Similarly, the antioxidant-related gene (sod and cat) expressions were synchronously upregulated or downregulated in the liver and gills in response to U. prolifera degradation. These results revealed that U. prolifera degradation decreased the growth performance and influenced the antioxidant capacity of Japanese flounder, while the 2103 flounder family had better advantages in the U. prolifera degradation condition. Therefore, the 2103 flounder family could be regarded as the potential flounder family tolerating U. prolifera degradation. The increased Fe content in the U. prolifera degradation water may be one of the main causes of the physiological alterations observed in Japanese flounder. [ABSTRACT FROM AUTHOR]

Species of Ulva have a wide range of commercial applications and are increasingly being recognized as promising candidates for integrated aquaculture. In South Africa, Ulva has been commercially cultivated in integrated seaweed‐abalone aquaculture farms since 2002, with more than 2000 tonnes of biomass cultivated per annum in land‐based paddle raceways. However, the identity of the species of Ulva grown on these farms remains uncertain. We therefore characterized samples of Ulva cultivated in five integrated multi‐trophic aquaculture farms (IMTA) across a wide geographical range and compared them with foliose Ulva specimens from neighboring seashores. The molecular markers employed for this study were the chloroplast‐encoded Ribulose‐1,5‐bisphosphate carboxylase oxygenase (rbcL), the Internal Transcribed Spacer (ITS) of the nuclear, and the chloroplast elongation factor tufA. All currently cultivated specimens of Ulva were molecularly resolved as a single species, U. lacinulata. The same species has been cultivated for over a decade, although a few specimens of two other species were also present in early South African IMTA systems. The name Ulva uncialis is adopted for the Ulva "Species A" by Fort et al. (2021), Molecular Ecology Resources, 22, 86) significantly extending the distribution range for this species. A comparison with wild Ulva on seashores close to the farms resulted in five new distribution records for South Africa (U. lacinulata, U. ohnoi, U. australis, U. stenophylloides, and U. aragoënsis), the first report of a foliose form of U. compressa in the region, and one new distribution record for Namibia (U. australis). This study reiterates the need for DNA confirmation, especially when identifying morphologically simple macroalgae with potential commercial applications. [ABSTRACT FROM AUTHOR]

Unialgal stock cultures for seeding the tank water can be used for the mass cultivation of seaweeds in artificial seawater, as in microalgal mass cultivation. High costs for artificial sea salt mixtures and distilled water would be required, however, to use artificial seawater in big tanks for commercial purposes, but frequent medium changes may not be required, since the major ions contained in artificial seawater, such as sodium, will barely be utilised by the cultured algae during long periods of time, even over years. Similar growth rates were obtained at the start and end of an experiment conducted with Ulva pseudocurvata cultivated unialgally for two years without water change, at a low algal density and with weekly addition of Provasoli Enrichment. Growth in this experiment was increasingly impeded due to gamete swarming events causing dark greenish water every few weeks. The experimental water had then to be boiled in order to kill the gametes. In a second experiment, this time performed at a high algal density, maximum yield values were 20–30 g fresh weight m−2 d−1, both for 2-year-old and newly prepared artificial seawater. These results verified the hypothesis that long-term Ulva cultivation in artificial seawater is possible without frequent medium changes. [ABSTRACT FROM AUTHOR]

The province of Sorsogon in the Philippines has a strong history of introducing farmed seaweeds and subsequently assembling farmers who put together the required enthusiasm to ensure successful production. Ulva is a green seaweed that has a wide range of commercial uses. Its farming, therefore, presents a promising opportunity for fishers to diversify their income streams and reduce their reliance on fishing. Using survey-based responses collected from fishers in Bulusan, Sorsogon, this study aimed to assess the knowledge of the local Ulva resources and the willingness of fishers to engage in Ulva farming, including identifying the challenges that may hinder its adoption. Our findings revealed that most Bulusanon fishers were knowledgeable about Ulva resources and could identify barriers to farming. They were generally receptive to engaging in farming Ulva, primarily due to the perceived economic benefits. Fishers with considerable knowledge about Ulva distribution were more likely to farm. While most Bulusanon fishers desired to farm Ulva, they were unlikely to be willing to learn, invest, or spend time doing it. Fishers may lack the desire to farm because, in part, it requires different skill sets as well as the challenges associated with marketing. This study provides valuable insights into the development of targeted interventions to promote the adoption of Ulva farming in the region. [ABSTRACT FROM AUTHOR]

The green seaweed Ulva is a model system to study seaweed–bacteria interactions, but the impact of environmental drivers on the dynamics of these interactions is little understood. In this study, we investigated the stability and variability of the seaweed‐associated bacteria across the Atlantic–Baltic Sea salinity gradient. We characterized the bacterial communities of 15 Ulva sensu lato species along 2,000 km of coastline in a total of 481 samples. Our results demonstrate that the Ulva‐associated bacterial composition was strongly structured by both salinity and host species (together explaining between 34% and 91% of the variation in the abundance of the different bacterial genera). The largest shift in the bacterial consortia coincided with the horohalinicum (5–8 PSU, known as the transition zone from freshwater to marine conditions). Low‐salinity communities especially contained high relative abundances of Luteolibacter, Cyanobium, Pirellula, Lacihabitans and an uncultured Spirosomaceae, whereas high‐salinity communities were predominantly enriched in Litorimonas, Leucothrix, Sulfurovum, Algibacter and Dokdonia. We identified a small taxonomic core community (consisting of Paracoccus, Sulfitobacter and an uncultured Rhodobacteraceae), which together contributed to 14% of the reads per sample, on average. Additional core taxa followed a gradient model, as more core taxa were shared between neighbouring salinity ranges than between ranges at opposite ends of the Atlantic–Baltic Sea gradient. Our results contradict earlier statements that Ulva‐associated bacterial communities are taxonomically highly variable across individuals and largely stochastically defined. Characteristic bacterial communities associated with distinct salinity regions may therefore facilitate the host's adaptation across the environmental gradient. [ABSTRACT FROM AUTHOR]

Ulva has received considerable attention since its merger with tubular Enteromorpha (Linnaeus) Nees based on molecular evidence. Nevertheless, several nomenclatural and taxonomic proposals concerning tropical and subtropical species are still pending in want of investigations based on the altered circumscription and criteria of genetic diversity. Enteromorpha ovata Thivy et Visalakshmi ex H. Joshi et V. Krishnamurthy has a restricted geographical distribution only at Gopnath, India. In the present study, we for the first time provide a polyphasic approach to ascertain its taxonomic position, using morpho‐anatomy, ecology and molecular taxonomy with multigene markers (rbcL, tufA and ITS rDNA). Phylogenetic analysis based on rbcL, tufA and ITS rDNA gene sequences supported the recognition of this species within the genus Ulva. The recent revision by Kumar and Palanisamy proposed the new nomenclatural combinaton Ulva ovata (Thivy et Visalakshmi ex Joshi et Krishnamurthy) Aron Santhosh Kumar and Palanisamy, but they did not give molecular evidence while doing so, which we accomplished. Our time‐calibrated phylogeny suggested that U. ovata diverged from its respective sister lineages ~ 4.46 Mya in the Neogene period of the Cenozoic Era. [ABSTRACT FROM AUTHOR]

The outbreak of Ulva in the Yellow Sea has seriously affected marine ecology and economic activities. Therefore, effective prediction of the distribution of Ulva is of great significance for disaster prevention and reduction. However, the prediction method of Ulva is mainly based on numerical simulation. There are two problems with these methods. First is that the initial distribution of Ulva is simulated using independent pixel-level particles. Besides, the influence of Ulva growth and diffusion on the drift is not considered. Therefore, this paper proposes a multi-module with a two-way feedback method (MTF) to solve the above problems. The main contributions of our approach are summarized as follows. First, the initialization module, the generation and elimination module, and the drive module are composed in our way. Second, we proposed an initialization method using rectangle objects to simulate the Ulva distribution extracted from remote sensing images. Thirdly, the drift and diffusion mechanism of the Ulva is considered to realize the two-way feedback between the generation and elimination module and the drive module. The results of our experiments show that the MTF performs better than the traditional method in predicting the drift and diffusion of Ulva. The code is already publicly available at https://github.com/UPCGIT/A-multi-module-with-a-two-way-feedback-method-for-Ulva-drift-diffusion. [ABSTRACT FROM AUTHOR]

Marine macroalgae (seaweeds) are important primary global producers, with a wide distribution in oceans around the world from polar to tropical regions. Most of these species are exposed to variable environmental conditions, such as abiotic (e.g., light irradiance, temperature variations, nutrient availability, salinity levels) and biotic factors (e.g., grazing and pathogen exposure). As a result, macroalgae developed numerous important strategies to increase their adaptability, including synthesizing secondary metabolites, which have promising biotechnological applications, such as UV-absorbing Mycosporine-Like Amino Acid (MAAs). MAAs are small, water-soluble, UV-absorbing compounds that are commonly found in many marine organisms and are characterized by promising antioxidative, anti-inflammatory and photoprotective properties. However, the widespread use of MAAs by humans is often restricted by their limited bioavailability, limited success in heterologous expression systems, and low quantities recovered from the natural environment. In contrast, bloom-forming macroalgal species from all three major macroalgal clades (Chlorophyta, Phaeophyceae, and Rhodophyta) occasionally form algal blooms, resulting in a rapid increase in algal abundance and high biomass production. This review focuses on the bloom-forming species capable of producing pharmacologically important compounds, including MAAs, and the application of proteomics in facilitating macroalgal use in overcoming current environmental and biotechnological challenges. [ABSTRACT FROM AUTHOR]